MK1 Suspension and handling Guide

[Zip]

Been browsing the internet on my day off and have found this:thumbsup:

Its a good read and might help a few people on here set up there cars suspension the best they can :)



Introduction

The foremost unique feature of the MR2 is the mid-engine layout, and with this, the car is agile, outstanding in traction and the sharp in handling. The first Japanese mid-engined mass-production car, the MR2, possessed all of the traits of a mid-ship vehicle... but it's twitchy nature challenged the best of professional drivers. As Mr. Sakurai, a former TRD development driver of the N2 Spec AW11 noted, "the car spun me around clean at Fuji Speedway ... I quickly counter-steered in a hairpin...but, it hit me like if I had no time to think...it's much like a F3 car I set up regularly...fast and unforgiving."

This wasn't the only character of the car resembling a formula car, however. On the AW11, the alignment adjustability is far more flexible than any other Toyota car in production trim to date. The tow, camber, castor each were adjustable at all four wheels. Such feature made great challenges to the tuners in those days to come up with the correct alignment. In short, there were so much possibility in alignments that it was just as easy to totally destroy the car's balance as was to set up correctly, or to a driver's favor.

Another factor making the AW11 a joy and a challenge to tune is it's engine, the 4A-GE that Toyota introduced a year before in the AE86 Corolla. It's original configuration was needing more power so a supercharged model was introduced after 3 years. Insider's rumors said that the supercharged model was a idea and product of Mr. Sakurai's strong push for such engine. The AW11 with the supercharger was now able to overcome handicaps of the heavy body structure and shine on tracks.



Before starting any AW11 project...

Since the AW11 you are starting will most likely be a well-used car, here are some things you will need to take care of before doing any modification. The first element of the AW11 that frequently needs service or is worn out of spec is the synchronizer ring and hub sleeve for the transmission. A tell tale sign of this is an oil leakage between the bell housing and the engine block. On supercharged models, there should be a smooth whine from the supercharger unit when operating and should be rattle free at idle. Do an oil change in the supercharger if in doubt and re-check. SC oil change kits should be available at dealerships with necessary filling syringe and oils. In all cars, before a modification, obtain new timing belt and all fluids and filters. On the suspension side, again as in all used cars, replace all your suspension bushings and recalibrate your alignment. TRD bushings are recommended for it's good resistance to drive train judder as well as fairly mild compliance in ride. If investing in a AW11, try to find one that's cheap, and work these new pieces in...the AW11 chassis is remarkably strong so there's not much difference between cars with different mileage.



Suspension for a more forgiving control

Any owner who drove the AW11 at it's limit have experienced that trait of twitchiness. The car starts to push or understeer upon braking and turn-in, and then suddenly tries to whip the tail around. The cause of this is that AW11 does not nose-dive enough for effective weight transfer due to it's mid engine layout. To counter this difficulty in handling, Sakurai, recommends modifying the timing and the amount of the nose dive. By reducing the compression rate of front shock absorbers, the amount of braking nose dive is increased, thereby making the transition more predictable. In the same respect, it's better to use a coil over system since OEM shock stroke isn't adequate when compression rate is reduced, causing full-bump when tires hit road irregularity. That's important especially on vehicles using lowered spring. Also, when choosing coil-over systems, try to find one that has extended-stroke shell casing, that has longer suspension travel than OEM. This way even lowered cars can be had with proper stroke necessary for good handling. By following the above, the initial understeer should be reduced to a much more predictable level.

Now the next step will be to balance the spring rates and shocks for easier directional inputs, or simply better handling. On street radials 4.0kg/mm spring rates on the front suspension seems best for giving good stroke without being soft. On the dampers, contrary to the soft compression necessary, you need one with stiff rebound characteristics. Once the front is down and giving good weight transfer for accurate steering, you don't want it to come back up too fast. Keeping the nose down for most of the turning phase keeps the car controllable with the steering wheel, counter-steers become more effective and natural. The camber can be modified to no more than 1.0 degree, since there isn't much weight there aggressive camber will make the contact patch less uniform under changing loads. The front sway bars also need not be replaced...the OEM works fine even with best of new street radials.

Next the rear suspension needs to be adjusted to make what you did in the front come to life. First, though, you should look at the brake balance. Since the AW11 has tendencies to lock the front wheels under even mild braking, you should search for a set of brake pads with 20% less frictional force than rear brakes. This comes from a little experimentation but using different brand/ materials to achieve this is common. This way, the front brakes will be used more for turning, and the rears more biased for slowing.

The inherent nature of the AW11's compact body and engine placement, the rear control arms had to be shorter than desirable. This creates a situation where the rear camber alignment change is too excessive when the car rolled from side to side. A natural way to suppress this effect is to make the car exhibit less roll in the rear by using stiffer springs and dampers progressively balanced. The use of 9 to 10kg/mm spring ratio will balance nicely with the front's 4.0kg/mm mentioned earlier. By using stiffer springs in the rear, the suspension will make less weight transfer and at the same time, making the loss of adhesion at rear more predictable and controllable. On cars with T-bar rooftops, a roll cage should be used with such stiff springs, so the body doesn't give in and create more stroke at even more unpredictable camber changes. The hard top models are fairly stiff in this respect and isn't necessary (unless of course, your track regulations state so for safety issues.) On cars lowered more than 3cm from stock, always use roll center adjuster blocks on the lower arm to correct the camber geometry as well as pivot center weighting. You can set the camber up to 3 degrees in the rear depending on tire choice using the setup mentioned above. For best balance, for non-supercharged models, use the same size and width tires at all four ends and correct handling and grip by alignment. An ideal size would be 195mm width in 14 or 15 inch sizes. On supercharged models, extra weight and power should be offset by the use of one size larger tires at the back with maximum of 225mm width.

Lastly, stay away from using pillow ball or ball-jointed suspension components as these parts are race-use design and make the car extremely peaky in demeanor. Additionally, these joints will stress the suspension mounts and can cause stress cracks over short period of time. They should be only used on race cars that are disposable after a season of runs. Even when changing rubber or polyurethane bushings, never use more than 200% stiffness over OEM for the same reasons.

There are many ways in which people set-up suspensions, so use this as a guideline in making your AW11 handle for fun factor. Depending on the diver skills, this isn't the only, nor the single fastest way to do this. But stay focused, the AW11 is the most easiest car to really screw up the suspension by setting it bad. Experiment, and you shall find a setting that's matched to your level and taste...

Most of all, have fun doing it! or else what do I write this stuff for?

http://www.club4ag.com/faq%20and%20tech_pages/aw11_mr2_tuning_guide.htm

[Sports Toyota Breakers]

Some good stuff, some talking out his @ss (225's needed on the rear of an s/c? err no).

[Rowdan]

Some good stuff, some talking out his @ss (225's needed on the rear of an s/c? err no).

I think he is suggesting using one size wider tyres on the rear..eg. 185 front : 195 rear (up to a maximum of 225), rather than saying you need 225's on the rear. :shrug:

[Sports Toyota Breakers]

GPWM old man, I'll stop frothing at the mouth now. Has anyone machined up some roll center adjusters yet? Would be a good market for them and easy to do I'd have thought?

[Jim-SR]

the AW11 is the most easiest car to really screw up the suspension by setting it bad

the author certainly got that right. maybe he should heed his own advice.

i disagree with just about everything in that article, il write a proper reply when i get a chance next week, quite busy this weekend. but running DOUBLE the spring rate on the rear, when the weight balance is 43/57% front to rear just about says it all lol

[Zip]

the author certainly got that right. maybe he should heed his own advice.

i disagree with just about everything in that article, il write a proper reply when i get a chance next week, quite busy this weekend. but running DOUBLE the spring rate on the rear, when the weight balance is 43/57% front to rear just about says it all lol


Ill be expecting one now:thumbsup:

[MartG]

I think he is suggesting using one size wider tyres on the rear..eg. 185 front : 195 rear (up to a maximum of 225), rather than saying you need 225's on the rear. :shrug:

I tried 185 front/195 rear for a while - understeertastic:naughty:

[Jim-SR]

right, ok. ive got some time to reply now, so here are my thoughts about the above article, and my own thoughts on how the AW11 should be setup. the easiest way is going to be to go through the article a point at a time and offer my own thoughts on it, and then il go through how i think the AW11 should be setup...


Any owner who drove the AW11 at it's limit have experienced that trait of twitchiness. The car starts to push or understeer upon braking and turn-in, and then suddenly tries to whip the tail around.
not sure that i even agree with this first statement lol. it CAN push on a little, but not if youre driving the car on its merits, most people try to drive it like other RWD cars. and its not THAT twitchy on turn in that it tries to snap oversteer EVERY corner. it can, and will, snap oversteer on the limits, but thats the natures of a mid engined car, with a low polar moment of inertia


The cause of this is that AW11 does not nose-dive enough for effective weight transfer due to it's mid engine layout
no it isnt, its the low polar moment of inertia (from an oversteer point of view) and a lack of front grip. nose diving has little to do with it, but obviously there is less weight transfer than on a typical FWD car


. To counter this difficulty in handling, Sakurai, recommends modifying the timing and the amount of the nose dive. By reducing the compression rate of front shock absorbers, the amount of braking nose dive is increased, thereby making the transition more predictable. In the same respect, it's better to use a coil over system since OEM shock stroke isn't adequate when compression rate is reduced, causing full-bump when tires hit road irregularity. By following the above, the initial understeer should be reduced to a much more predictable level.
the wrong area of the car is being targetted, so this isnt likely to work. reducing the bump (aka compression) damping is the WORSE thing to do!! there is a common misconception (even in racing) that dampers should be low on compression and high on rebound. the winning cars in most top racing series are winning because they do the opposite (and also run on softer springs because of it, we will get to that later). if you want the front end to dive more you opt for a softer spring rate and then reduce the rebound damping. reducing bump damping with softer springs is going to cause the car to dive rapidly down, which will totally unsettle it, stiffer bump damping will control the dive a lot more. and you shouldnt need more compression stroke to avoid the dampers bottoming out, you shouldnt be diving the car that far to start with, under braking, cornering, or any other situation. you want SOME dive and you want some weight transfer, otherwise youll just lock wheels under braking. but this article is suggesting excessive amounts IMO




Now the next step will be to balance the spring rates and shocks for easier directional inputs, or simply better handling. On street radials 4.0kg/mm spring rates on the front suspension seems best for giving good stroke without being soft. On the dampers, contrary to the soft compression necessary, you need one with stiff rebound characteristics. Once the front is down and giving good weight transfer for accurate steering, you don't want it to come back up too fast. Keeping the nose down for most of the turning phase keeps the car controllable with the steering wheel, counter-steers become more effective and natural.
the front spring rate is actually half sensible. my personal thoughts are 185lbs/in on the front, which is yet to be tested, but 225lbs (which is what 4kg/mm is) is fairly close. go too stiff and youll lack weight transfer, and lock wheels up under braking and sacrifice grip for no good reason. the damping comment are the most classic of misconceptions though. you dont want to reduce the bump (as said), and you certainly dont want to wind the rebound up. stiffer rebound with softer bump on soft spring will cause the car to nose dive rapidly, and then stay down into the corner rising back up very gradually. youd rather that the car didnt dive down so heavily to start with, and then you dont really want it to stay down afterwards. you want just enough rebound to control the spring, and nothing more. thats the way that will make the car fastest (most peoples driving style would probably need adjusting to it though), however cranking on the rebound is often what feels "fastest" to most drivers. granted, if youre using a car purely on the road then what feels fastest and gives the most confidence to the driver is probably best. however, when you get to a roundabout and FWD cars are going round the outside of you youll want to have the car setup to go faster lol. there is definitely a compromise to be found, some people will just feel more comfortable with a bit of excess rebound, but if you want the fastest setup, try to avoid adopting the stiff rebound mentality. the article mentions about the stiffer rebound setup giving more accurate steering. this is actually quite an accurate observation by the driver, as it will, the front end will feel very pointy and will dart about exactly where you tell it to. but its at the expense of grip, and that isnt to say that a high-bump sensible-rebound setup wont still give accurate steering which feels good to the driver, it will be more progressive and less pointy too, which is good on a car that is overly twitchy in the first place. its just that tons of rebound tends to feel "good" to everyone :D


The camber can be modified to no more than 1.0 degree, since there isn't much weight there aggressive camber will make the contact patch less uniform under changing loads.
sensible enough, for track use you might add a bit more, but id doubt more than 2 degrees at the most on road tyres


The front sway bars also need not be replaced...the OEM works fine even with best of new street radials.
the front anti roll bar (plural? i didnt realise there were 2 lol) could do with being a bit stiffer. going stiffer on the front roll bar will reduce body roll a bit on the front, which is no bad thing, and it doesnt sacrifice too much elsewhere. dont go excessively stiff (i havent found a desirable rate to go with yet, but i havent started experimenting yet either. once i do il report back). Americans seem to have an obsession with not running ARB's, or running them really soft. but then they also have an obsession with massively stiff springs, which makes the ARB's less required, since there isnt any roll to start with


The inherent nature of the AW11's compact body and engine placement, the rear control arms had to be shorter than desirable. This creates a situation where the rear camber alignment change is too excessive when the car rolled from side to side.
not sure that id fully agree. the rear geometry doesnt look like it would cause that excessive a camber change. il check it properly in a couple of weeks and measure the change in camber, but i dont think its anything particularly drastic. especially not bad enough to require the next step (see below). if this is the case, shifting the roll centre a bit higher could help to reduce the camber change as the car would exhibit less roll through the geometry, but thats something to be discussed another time, it complicates things too much and to be honest i dont have a strong enough understanding of it myself to be preaching it to others :D

CONTINUED BELOW....

[Jim-SR]

A natural way to suppress this effect is to make the car exhibit less roll in the rear by using stiffer springs and dampers progressively balanced. The use of 9 to 10kg/mm spring ratio will balance nicely with the front's 4.0kg/mm mentioned earlier. By using stiffer springs in the rear, the suspension will make less weight transfer and at the same time, making the loss of adhesion at rear more predictable and controllable.
the worse comment in the entire article. this is by far the worst thing about this setup. 10kg/mm works out at 560lbs/in, thats more than most touring cars are running on SLICKS, and touring cars weigh more!! even 1400kg Evo's on slicks run less than that. its a ridiculous spring rate to suggest, and shows a complete lack of understanding of how a car works.

the basis of running these super stiff springs is to reduce the roll because there is excessive camber change in roll (allegedly) and by reducing roll, youll reduce this camber change. going ridiculously stiff on springs will certainly reduce the roll (560lbs would pretty much ELIMINATE roll, the back end would be absolutely solid, it would hardly move at all), but at the expense of traction and grip. youd be constantly spinning the rear wheels (im surprised the article doesnt recommend an LSD as well lol), and the car would be horrific in cornering, youd get masses of oversteer, and it would snap big time. youll be relying mostly on the tyre deflection, and when tyres reach their limits they tend to be far from progressive, whereas springs and dampers can control things much more progressively.

the correct way to deal with the rear suspension would be to run a spring rate more in the region of 200-300lbs/in and about 10% stiffer than the front springs (given the slight rearward weight bias). my personal thoughts are 225lb springs. then you combine these springs with a stiffer anti roll bar (more so than in the front), and if camber change really is a massive issue then look at the roll centres, but i think this is a minor problem, and not one that an average road user will need to worry about. in terms of damping, running stiff bump and soft as possible on rebound is again the best way to set it up. if we look back at the article and the way they tell you to balance the car, they are saying soft bump and stiff springs on the front, and then super hard springs on the rear, but not saying youll need to crank the rebound up big time to deal with the springs. so what will happen on braking is the front will dive due to having little resistance, and then the super heavy rear springs will be acting on less weight (due to weight transferring forwards) and thus will sit the rear end right up, further pushing the front down. the back end will be properly loose, and as you turn in youll break it away straight away. the front end will stay down, the rear end will skip about all over the place due to the damping not controlling the overly stiff springs, and youll probably go sideways into a tree. its actually a DANGEROUS setup, its so badly mismatched and unbalanced. on track it might work slightly differently, but it will still drive like crap, even if it isnt quite so dangerous as there is room to slide the car around a bit

as said earlier, most people will feel more comfortable with a bit of excess rebound, so on the rears you may want to push the rebound up a bit. but rebound compromises traction. go too stiff on rebound and youll be forever spinning the rear wheels up out of corners, even if the car does feel kinda like a go kart. so try not to use too much.


On cars with T-bar rooftops, a roll cage should be used with such stiff springs, so the body doesn't give in and create more stroke at even more unpredictable camber changes. The hard top models are fairly stiff in this respect and isn't necessary (unless of course, your track regulations state so for safety issues.)
not necessary if youre sensible on spring rates. although a stiffer chassis can never hurt (the cars performance at least, it can hurt you spine lol)


On cars lowered more than 3cm from stock, always use roll center adjuster blocks on the lower arm to correct the camber geometry as well as pivot center weighting.
fairly sensible suggestion, one of the few in the article


You can set the camber up to 3 degrees in the rear depending on tire choice using the setup mentioned above.
you wont want to go that far on the road, and probably not on track on road tyres either. its a matter of experimentation, but id start at 1.5 degs and see what its like, and either add or subtract depending on how the car drives


Lastly, stay away from using pillow ball or ball-jointed suspension components as these parts are race-use design and make the car extremely peaky in demeanor. Additionally, these joints will stress the suspension mounts and can cause stress cracks over short period of time. They should be only used on race cars that are disposable after a season of runs. Even when changing rubber or polyurethane bushings, never use more than 200% stiffness over OEM for the same reasons.
again, quite sensible for road use. rose jointing suspension components is for track use only really, not least because with the quality of UK roads youll break your spine with everything that hard!!

CONTINUED BELOW...

[Jim-SR]

There are many ways in which people set-up suspensions, so use this as a guideline in making your AW11 handle for fun factor. Depending on the diver skills, this isn't the only, nor the single fastest way to do this. But stay focused, the AW11 is the most easiest car to really screw up the suspension by setting it bad. Experiment, and you shall find a setting that's matched to your level and taste...
i have a feeling from the comments in this last paragraph that this guide is aimed at your average road user who wants the car to "feel" better. but i dont see why it should be necessary to "dumb it down". people are informed enough to make their own decisions, so my advice is to start out cautiously, maybe run a bit more rebound than is desirable, and gradually take the rebound off. the car will be "harder" to drive for the average driver in the optimum fastest state of tune, but once you adapt to it, it will be infinitely more enjoyable. you just need to start out cautiously and work up to it. if you get dampers with rebound adjustment (i cant stress enough how good Koni's are for the money) then it gives you a lot of scope for improvement. convert the strut cases to coilover as well and then you can use 2.25" or 2.5" springs and have a much wider choice on spring rate, and also adjust spring preload and ride height

the most common way people think to setup damping is to get it ballpark, and then drive it. invariably one end of the car will slide more than the other, so they tune it by INCREASING rebound on the end that doesnt slide, until both ends are sliding together. the problem is that they are missing the point that the car is now sliding!!! the better way to tune it is to REDUCE the rebound on the end that IS sliding until both ends are sliding together, but at much higher cornering speeds. dont sacrifice the end of the car that is working well in order to balance it to the end that isnt working well. improve the end that isnt working well (if it means making major changes then try to do it, even if it is more effort, or possibly more expense (within reason)) and then youll have an overall faster car

hopefully that gives some insight. i wont claim to be an expert, im far from it. i do at least work in the suspension trade though, and most of what i know is derived from my bosses, who CAN claim to be experts. i did speak with our technical director this afternoon to ask if he had any corrections to make to my original reasoning on how the AW11 should be setup, just to make sure i wasnt misinforming anyone, and he pretty much agreed with my thoughts, he added a few details here and there. so i hope this helps people :) id disregard the original article completely, it is based around the usual misconceptions, most of which seem to get made in America. but then they do tend to drive mostly in straight lines and round ovals, transient cornering isnt their specialty ;):D (that isnt a dig at the average American car owner btw. its meant more as a joke really, but generally American racing principles dont have the most solid bases. road racing is so insignificant in popularity compared to Nascar and oval racing that there just doesnt tend to be the same level of knowledge as in Europe. but there are of course still some very knowledgeable guys. so dont take offense if youre just an MR2 owner from the states reading this ;) i actually work with a team in the states from time to time, and tend to learn more about race cars whilst im out there than i do in the UK though, ironically :D)

[Jim-SR]

P.S. i just wanted to add a brief overview of how damping and springs work, as i couldnt easily implement it above...

a damper (very) basically consists of a cylinder filled with oil with a hole in the top that a shift can move in and out through. on the end of the shaft is a piston which seals to the sides of the cylinder, but contains some form of bleed mechanism which allows oil to pass through in controlled amounts. the system is varied depending on the direction the piston moves in, which gives you your bump and rebound valving. something il say here which isnt really related, but which most people understand wrongly is that "gas" dampers (aka gas filled struts, emulsified dampers (gas mixed with the oil, some dampers have gas in a seperate chamber),etc) still contain oil. ALL dampers have oil in them, and dampers without gas when compressed will stay compressed, they dont pop back out. the gas inside dampers will cause them to push the rod back out, but this is at such a tiny force it had no effect on the car. the gas pressurises the inside of the damper so that it can allow for expansion of the oil under heat and allow for fast movement of the oil and prevent/reduce cavitation in the oil

so youve got bump damping and rebound damping. the sole purpose of the damper is to control the SPRING, it is the job of the spring to control the ride of the car

so the spring is compressed, it pushes the damper down and the dampers bump characteristics control the rates at which the spring can be compressed. all the damper really does is offer up an opposing force to the spring. the car pushes the spring and damper together and inside the damper the piston being forced through oil offers up resistance, which manifests itself as an upward force opposing the movement of the car and spring. stiff bump damping leads to a slower rate of compression. the way it works is quite simple, its the fine details in what sort of rates of compression you want which is where it gets complex lol

rebound is the opposite of bump, this is the force which resists the damper expanding again. as said above about gas dampers, the damper itself doesnt possess enough force to push the cars weight back up, they dont generally possess enough force to overcome a human pushing the rod in, depending on the gas pressures used. if there wasnt a spring on the car, the damper would expand back out. in rebound, the spring is trying to expand (as it naturally does) and in order for it to do this it has to pull the rod back out of the damper. the damper offers a force to resist this. stiffer rebound causes the spring to expand more slowly, again, its a fairly simple concept.

now to consider dampers with relation to spring rate. if you have a soft spring then the cars loads will compress it more easily. thus you ideally need stiffer bump damping to stop the spring from compressing really quickly and unsettling the car and causing excessive initial body roll. the rebound however can be softer because there is less force from the spring trying to expand the damper. since the damper is only there to control the spring, and the spring is pulling on it less hard, it makes sense that less rebound is required (generally, im stating this in very basic terms here, things are rather more complex in real life, but the basic principles still apply on the most part)

stiffer springs on the other hand compress less, and are less willing to compress, so bump damping can be softer. rebound on the other hands needs to be much stiffer, its basically the opposite of the above

now here are the 2 issues....

1. damping is there to control the springs, but the rate at which the wheels move is the key to a car gripping and handling well. so if you are needing to crank rebound up to cope with a stiff spring, you are also going to sacrifice traction on driven wheels for example. cars are dynamic objects, everything affects everything else

2. most people dont change dampers, the first thing they opt to change is springs (usually for lowered items). jap cars come with tons of rebound from the factory, japanese roads are really smooth, and japanese manufacturers like their cars to be pointy and feel like go karts, it sells well to people who dont really know how to truly drive the car. and this excessive rebound means that the car lends itself well to stiffer springs, as the dampers control the spring just fine in rebound and so people think this is what is best. the problem is that the bump damping is then far too soft for the stiff spring and the balance isnt there. it usually feels good, but it isnt fast. how many times have you seen scoobies and evos getting destroyed on track days by mk1 golf, 106 gti's, clio 172's, etc which are 200bhp down on them, but just destroy them around corners? most scoobies and evos are on cheap import dampers that are overly stiff on rebound, and are then stuck on stupidly stiff springs. the fastest track evo's run about 1-200lbs softer on spring rate than the average track day car, and their damping curves are basically turned upside down lol

thats not a particularly comprehensive guide on the basics of damping, its just a brief overview so that some of the above will make more sense. damping force changes dependant on speed, and its the fine tuning of low speed, mid range and high speed damping that determines how well a car sticks to the road, and the feedback and confidence that it gives the driver. but hopefully it gives enough insight to get people thinking :)

[Marksman]

:hmm:, interesting stuff, thanks for taking the time to write it. I now need to read it again.

Ta,

Owen.

[Marksman]

OK real numpty question, as I'm sure you've realised I'm new to this:-

When you talk about increasing rebound are you talking about increasing the rate that rebound is allowed, or increasing resistance to it?

Ta,

Owen.

[Jim-SR]

increasing the resistance that the damper gives when the spring is trying to expand. so yeh, increasing resistance to it. as said in the last of the posts, the damper never actually moves itself, it just acts against the spring. in compression it RESISTS the compression of the spring, and in rebound it RESISTS the rebound/expansion of the spring.

hope that clears it up a bit, feel free to ask questions about any part of it though, i dont mind answering them where i can :) as strange as it may sound, answering questions actually helps me to further improve my own understanding, because it gets me to think more and more about what a car is doing in order to try and answer questions. i learn more from writing things like the above (well, from thinking out what im going to write) than i do from reading about the same subjects :D

[Marksman]

Ah, right, that makes sense now. My initial (incorrect) assumption was was tother way round and that by increasing rebound you were increasing the speed that the suspension would decompress itself, no wonder the tuning guide didn't seem right!

Ta Jim :thumbsup:

[Zip]

Thanks Jim:)

You better stay around on these forums for a long time to come :mrgreen:

[nik]

great informative stuff..top work..

[Jiff Lemon]

as strange as it may sound, answering questions actually helps me to further improve my own understanding, because it gets me to think more and more about what a car is doing in order to try and answer questions.

There's a great line in one of Douglas Adams books where a character explains that to truly understand something, you have to explain it to a complete novice as it's only then, when your breaking it down into its simplest format, that you really begin to understand it.

Some of the best IT people I know are ex-motor trade because its the same mindset - taking something technically complicated and breaking it down into easy to understand chunks and then applying a logical thought process to it.

Don't ever stop skimping on the posts, we've plenty of bandwidth :thumbsup:

[Jim-SR]

another thing i forgot to mention above, which is just a quick overview (as i lack the knowledge at present to expand fully on the below)....

ive mentioned the term "road tyres" quite a lot, the reason being that 99% of people who read the above will run road tyres, even on track days. for those who dont, things are different

if you ever run slicks, or even semi slicks, anything with significantly more grip than a road tyre, then the car will want setting up differently. first and foremost youve got 3 times more grip from the tyres so youll get oodles of grip regardless, but that doesnt mean you cant still optimise things. camber settings will probably change quite a bit, as will tyre pressures, but it depends on the tyre in question as to what wants changing and what to. as with road tyres, youve got varying degrees of sidewall stiffness, tread compounds, contact patch deflection, etc

damping will be a totally different ball game, im not 100% what youd do to an MR2 if you stuck slicks on it, but im sure there would be an aspect of trial and error to it! youd definitely go stiffer on rebound, reason being that for slicks youll almost certainly run stiffer springs, and youll need the extra rebound to cope with the springs

youll only ever be using slicks on track (unless youre insane :D) so youre talking very smooth road surfaces, and little in the way of bumps. so running the stiffer springs isnt compromising grip and traction so much. also with the massively improved lateral grip slicks have you dont need to rely so heavily on weight transfer to maintain traction. the stiffer you go on spring rate and rebound though the more work you ask the tyre to do, which results in faster wear rates. in modern F1 the car with the best suspension is usually the one that manages the tyres best, as the aero is responsible for just about everything else. so all the suspension really does is manage tyres (within reason, it still makes a difference, but not as much as a car that relies on mechanical grip). its one of the main reasons why Honda have been awful for a couple of seasons, you always hear them talking about not being able to get tyres upto temperature enough, etc

even with slicks on an MR2 though, you still wouldnt be running anywhere near 500lb springs on the rear!!!

[Drangdin]

Well the original article came from club4ag so that explains alot of it. Over there they think that sliding the rear end around makes you faster... or at least it makes you look like you deliver tofu for a living.

[MartG]

Over there they think that sliding the rear end around makes you faster... or at least it makes you look like you deliver tofu for a living.

I always remember a line from Emerson Fittipaldi's ( 2 x F1 World Champ )biography - "Sliding is fun, but it isn't fast"

[millentubby]

not sure if it was this thread where poeple were looking for roll-centre adjusters, but have a look at this!

http://translate.google.com/translate?hl=en&u=http%3A%2F%2Fwww5d.biglobe.ne.jp%2F~fos4416%2F

Google's translator tool thingy is ace!

[crt87]

Jim-SR that looks a great read although i haven't read it yet (posting comment to find it easier later)

[Gouky]

i really disagree with the 1deg of max camber. she leans over quite a bit on mostly stock suspension:

http://www.twobrutal.co.uk/forum/images/recovered/2011/11/24.jpg

we run 2.5* camber up front and 2.1* in the rear and we tend to still overheat the outside of the rear tires.

this car needs more swap bar to stop the camber going nuts in a turn, but we can't do that in our class.

[Diesel Meister]

This is one of my favourite threads, so I figure I'll post here:

At the meoment, I'm running Koni Yellows (single adjustment) with GC sleeves and 200lb front, 300lb rear springs. I'd like to be able to run as soft as possible due to UK roads being rubbish and me liking to stay in tiuch with the surface when pressing on. I know I need to address my offsets and figure out what wheels and tyres I can get a way with, but bearing mind my car is running quite a lot heavier than standard with a V6 and SW20 turbo running gear, am I in the right ballpark?

It seems pretty stiff, especially with 45 and 35 profile tyres (215F and 245R R16s) but better balanced than before. Traction is still pretty awesome but I managed to trouble it 20 yards outside of a junction as I opened her up on a slight gradient (cold tarmac!) - no drama just a very gentle squirm with a gentle squeeze through the meat of 2nd. Nice. Given the 245s are no longer available and I'm not prepared to go to 17s, I'm considering going with 205 / 225s on the current 16x7.5in rims, or maybe even some 15s....

[snowtigger]

I think 275lb or even 265 on the rear springs mate and I know that 2nd gear snatch well, the sudden umph wants to throw you into a hedge/wall/barrier/ditch/lamppost I've been talking to ohlins uk about sorting a suspension upgrade for our v6 engined mr2s either mk1 or mk2 , they have there dfv tech which is like next gen stuff so you can have comfort and sporty suspension.

Had a word with other suspension company's and some of there products just aren't suitable or you have to compromise on what you want, I.e ride comfort or track handling or drag strip, as on a drag strip you need softer rears while track racing you want it hard but I'm getting old so need a softer ride.

I think 300 is way to high for the rear even 200 on the front is to hard 185 or lower as you want some give .

[Diesel Meister]

Thanks Tiggs. I was thinking I could go for 20-30lb/in softer front to rear but I will also need to look at my arches :)

[snowtigger]

Go coil over mate there's a few the bc racing you can keep the spring at the poundage you want, and lower the shock tube to what ever hight you need then it takes the pain out of hight and spring length and poundage, don't go for there inverted design though as have been told that it would need rebuilding/sorting every year.