View Full Version : "SW13" mk1 spaceframe build thread
decided it would be best to start a fresh thread for this, rather than carry on in my rust thread. also, im not 100% commited to a 3S-GTE yet, so il put the thread in here for now rather than the mk1.5 swap forum
the name in the title though is what an AW11 becomes when you stick an S-series engine in it (which is top of my list of choices at present), and the chassis designation cant be 11 because its changing too much, and 12 was already used on the Group S rally car. so 13 is the next progression
hence "SW13"
made a small amount of progress today. just cutting away as much of the front end as possible, leaving as many of the major structural supports in place as i can. that way i dont have to worry at this stage about taking measurements, etc so i can replicate the front mounting locations, etc later. i want to have a fuller picture of how the chassis is constructed so i can figure out what i need to change, and cutting the non-structural areas away is helping a great deal.
so here is the car at the start of the day...
http://www.twobrutal.co.uk/forum/images/recovered/2009/02/88.jpg
and here is the front end after an hour or so of sparks...
http://www.twobrutal.co.uk/forum/images/recovered/2009/02/89.jpg
managed to do all the grinding without removing anything, and with some great care i didnt touch any of the suspension mounts, brake lines, etc which were perilously close to the blind side of the areas i cut. next stage however is to drop the steering rack and most of the suspension, plus remove all the brake hardlines and brake M/C + booster, etc. so its a lot more boring and labourious. ive got to cut back most of the "stepped" area in front of the bulkhead so that i can get complete access to the front chassis rails. then i can cut the inside and upper surfaces off of those, treat the rust, grind back all of the metal to clean steel (e.g. rust removal), and then im going to weld the new box sections on top of these. it can never hurt to be double skinned on 2 sides, plus the new box section will be located to the roll cage and the sill box sections (these will also get cut off though later and be square box sectioned, saves dicking around with profiled shapes, and square is stronger!)
also i reckon i can probably lose 80-150kg more through doing things this way than i ever could have whilst retaining the stock chassis. unsprung weight will benefit HUGELY too.
expect updates to this thread to be rare and slow. especially if the weather gets cold again!! at present it is just cold enough to wear a jumper (and save my delicate skin from hot sparks), so perfect grinding weather. another fortnight like this and i might even be ready for welding stuff :D
GregHoon
17-02-2009, 15:02
The weight saving sounds very good. Will this be all over to keep the weight bias the same front to back? The spaceframe in place of the original chassis plus carbon fibre or fibre glass secions from nik would see a terrifically light car. When you say you are going for an S engine do you mean either 3sge or 3sgte?
Such a light car would mean the braking and steering would be on par with a 3s-gte engine i'd have thought. Would be an awesome combo. Look forward to see how you get on:thumbsup:
Greg
good start..!
im just down the road in dorset if you need a hand..may just pop along and have a nose if youre around during the day this week..
greg: there will be plenty of metal removed all over, but the spaceframing is predominantly up front. the rear is a lot tighter for space with a transverse engine (ive thought about going longitudinal, but it introduces so many issues with transmissions (most of which are incredibly heavy) and packaging that its not worth the effort, the gains are minimal) so there will be less happening back there than up front. front will be pushrod (with bell crank) double wishbone suspension, rear will be double wishbone still but more likely to have the damper mounted where the macpherson strut would normally be.
as for engine, S-series will be a 3S-GTE in my case, somewhere around the 320bhp mark for starters. best thing about that engine is that there are very few limits on how far you can push it. if the car gets finished and 320bhp isnt enough then 400-450bhp isnt out of the question. and if that still wasnt enough, 600bhp+ is do-able, at great expense. so that is a major positive!
nik: i should be around most days this week. if youre coming up this way let me know and il see what im doing
as for progress this afternoon, i didnt do much. just dropped the steering rack out, removed all of the clutch and brake hardlines that come up through the stepped section in front of the bulkhead. tomorrow morning il cut that out, remove all of the brake and clutch stuff, and see where im at. gotta figure out exactly where all of the chassis members are first because id like to keep as many as possible. then il drop the suspension off at some point
GregHoon
17-02-2009, 17:33
Yeah Jim sounds great man. I am running my rev 1 3sgte at around 15psi and i reckon maybe around 250bhp. It's faster than anything i've come across so far but it could do with more mid-range grunt and a bit of super boost. So yeah 320bhp will be good and like you said can keep going up the stages. I guess a blown v6 would be good but i think the mk1.5 is heavy enough. Will have to look up the figures. Why add weight when you're going to do so well reducing it ;)
I'm waiting to see what toffer's car will be like as he's looking to get 450+bhp once the engine is run in. You looked at his thread?
Greg
I think 320BHP is pushing the limits of a mk1, any more and it risks being undrivable.
Mine is about 280-300 and theres times where i think this is too much!
Jim, i cant wait to see progress on this! It'll be magic when its done, deffo go for a 3SGTE :)
Murf, this isnt really directed at what you said, more at the general perception that the MR2 community tends to have, so dont take it personally. i dont really know what mods your car has.
320bhp is probably pushing the standard car, but most people overlook the fact that if you are going to more than double the engine performance, you need to more than double the chassis performance as well (in each individual area - suspension, brakes, rigidity, etc). i see plenty of people spending £2k+ on engine conversions and engine tuning, but i dont see very many spending £2k on suspension. 320bhp wouldnt be hard for a typical mk1 to handle if the suspension was up to the job. Koni's were designed for 122bhp with soft springs and road tyres. stick 320bhp in the car, stiffen the springs, and then possibly in some cases run it round a track on road-slicks and youre asking more of the car that was ever intended for it
at some point in the not-so-distant future there may be a decent upgrade available for mk1 MR2's that goes several steps beyond Koni's (in performance AND price, because you genuinely get what you pay for (or less) in suspension, spend £400 and you get upto £400 of performance. spend £1400 and youll feel a grands worth of difference if you buy a respectable product), hopefully a few people will spend the same money on suspension as they do on engines and perceptions will change a little.
GregHoon
17-02-2009, 22:48
Well i guess when there's a lot of weight coming off the car so he won't have to have such a highly tuned engine to get similar power to weight ratio to yourself murf. So maybe 320bhp isn't even neccesary and will save him the expense.
To my knowledge murf has one of the most powerful 1.5 so he will know about what the chassis can handle better than anyone. Out of interest murf what is it that you feel makes it too much? Back end coming out or just generally too much?
Greg
Marksman
17-02-2009, 22:50
Agreed. I had a passenger ride round Anglesey in a MK1 where the suspension cost more than the rest of the car and it was sublime. Given some real power it would have been a whole new ball game.
Owen.
todays update!
stripped off the suspension, all of the brake and clutch hardlines, master cylinders and brake booster. chopped off the "stepped" area in front of the bulkhead and cut off the front radiator mounting frame, and thats about as far as ive got so far. got relatives down for the rest of the week so probably wont get any further until the weekend, i need to do some very careful planning for the next stage though
http://www.twobrutal.co.uk/forum/images/recovered/2009/02/91.jpg
http://www.twobrutal.co.uk/forum/images/recovered/2009/02/92.jpg
the next area to work on is getting the current chassis rails cut out, without deforming ANY of the side panels (e.g. strut tower, the panel that the front wings mount to, headlight mounting panels, etc) and then cutting new chassis rails for 4mm walled box section to weld in their place. i think i should probably try to source the box section fairly soon. also i either need to learn to weld properly really fast, or find someone else to do it lol im getting to a point where welding would be beneficial!
the car must weigh about 600-650kg at present (bearing in mind its essentially a bare shell apart from the rear suspension, doors, glass and rear bodywork). i dont think that 800-850kg will be an unrealistic end goal for weight! was looking at power-weight ratios yesterday, and 320bhp with 800kg would be 400bhp/ton. thats in the same ballpark as a Ferrari F40 and Porsche Carrera GT. those would be some amusing cars to embarrass :D
GregHoon
18-02-2009, 15:58
400bhp/tonne? Think i felt a twitch lol. Will be awesome.
Greg
320bhp is probably pushing the standard car, but most people overlook the fact that if you are going to more than double the engine performance, you need to more than double the chassis performance as well (in each individual area - suspension, brakes, rigidity, etc).
Well, my car has upgraded brakes (st205's), Koni's with lowering springs, poly bushes, cusco braces front and rear, lightweight wheels, good tyres and minimal rust.
What sort of chassis upgrades should i be looking at? I've removed as much weight as possible, without getting rid of body panels!
Out of interest murf what is it that you feel makes it too much? Back end coming out or just generally too much?
It's prob more to do with my lack of driving skill than the car itself! Its actually pretty grippy once you've learned to read the road conditions! Sometimes it just catches you off guard and you think "fook me" and turn the boost down a bit! I was planning power upgrades for it but ive decided that its pretty well balanced the way it is so i'll prob try and get rid of some more weight and keep fighting the rust :)
GregHoon
18-02-2009, 22:35
I get you murf:thumbsup:.
The odd time mine has had me reaching for new undies is when i haven't taken into consideration the way the road undulates or the gradient and then the back has swung away from me.
The previous owner told me not to push it in the wet and he is 100% right. I have had it understeer in the wet, oversteer and fish tail back and forth. Plus, when i'm giving it some unless the road is nice and dry i can definitely feel slipping of the tyres and it's not getting all the power down. I guess it's for the same reason that Lambo's etc have gone four wheel drive to put the power down when they reach a certain bhp/tonne.
The car, as designed, wasn't built for what we have done to them and i can see what Jim is saying about the improvemnts that are needed to the suspension and brakes so it matches the acceleration. What to do however i have no idea. I'm thinking a nice pair of coilovers won't be quite enough. I think Jim's approach is quite promising but of course it is a lot of work. If you can't make the wheelbase any larger and it's an old design approach the suspension has then we are left with weight reduction to increase the vehicles suspension and handling.
Greg
a good set of coilovers would go most of the way to solving the issues. you can always go further than that, but damping and spring rates are the primary issues. there isnt a really good set of dampers available for the AW11, its because its so old and nobody spends proper money, so the market doesnt really exist. so at present, there isnt a set of dampers off the shelf for an AW11 that i would regard as anything more than an average-to-decent fast road setup (Koni's). hopefully in the not too distant future there will be a setup that can range from excellent fast road right up to excellent trackday/club-level race. but it will obviously cost accordingly. and most people dont want to spend £1500-2500 on dampers when their car only cost them £1000-1500. but they are always quite willing to spend twice the cars value on the engine (again, this isnt a dig at anybody, just a generalisation). it doesnt apply only to MR2's either
I think it was Paul that fitted Mk3 Ohlins coilovers to his mk1, would it be worth doing this and getting them revalved by, say, someone that worked for Ohlins *ahem*
used to work for the Öhlins UK distributor. i work for myself now on a damper side of things
mk2 Öhlins are potentially a better fit for the mk1, and are pretty good. they can certainly be used, but they can be hard to get hold of, and there isnt a fluent supply of them anywhere else in the world except Japan. and to get them out of Japan is crazy expensive and makes it totally not worth the hassle.
then there are custom made Öhlins, but youre talking big money there.
i am working on something better, but whether it happens or not remains to be seen. hopefully it will, and if it does then there will be a good upgrade option available in the not too distant future. when ive got more information il share more information ;)
What coilovers are available off the shelf for the mk1? Anything at all?
D2/F2/Ksport/G4 - all the same, cost in the region of £600-750 typically. think most places charge somewhere around £650 new. you get what you pay for, in that they are shiny anodised aluminium, adjustable in every way (spring height for "preload" (it works more as a droop restrictor though, you cant really preload a macpherson strut), adjustable ears for independant ride height, adjustable anti roll bar droplink bracket height, one way damping adjustable, predominantly in rebound). but they spent all the money on the shiny cases, one-piece machined adjustable ears, etc and didnt spend ANY money on the actual damper. so the damping specs are horrendous and just dont work. and the overall quality isnt great either, they are typical mass produced Taiwanese car product (they make awesome electronics, but their car product thus far doesnt cut it)
BC Racing - similar affair to the likes of D2. their representatives all over the world claim endlessly that their product is nothing like D2, the quality is higher, performance is better, etc, etc. ive seen the product, its the same build quality as D2's. ive seen the damping graphs, and they are almost identical to D2's. they run the same spring rates, and are also made in Taiwan. they claim to be an improvement, they offer much of the same. at a similar price. it would never surprise me if they dont come from the same factory!
Toda Fightex - £1800 for a damper made by a company that are more renowned for their engine products. they are clearly just trying to trade on their name alone and charge a LOT of money for something that probably performs in a similar bracket the D2 and BC Racing. so far as i know there isnt a single set on an AW11 in the English-speaking world. ive never heard of anyone running any on any of the multiple MR2 communities i frequent, which span most of the globe. so unless they are big in Japan...
for £1800 there are better custom options
a few people have spoken of using 2-way adjustable Koni inserts. not sure that anyone has yet. they arent bad dampers, would probably cost the best part of £1000-1500. but Koni technology has barely changed since the 1950's. it still works, but then so do steam engines (theyve built a brand new steam engine that came past my house last weekend), but you dont see steam engines carrying passengers around the world all day everyday. the new technology works better (in both cases)
then youve got the best road car options of ground control coilover sleeves coupled with Koni/Tokico/KYB dampers (depending on budget and application). not proper coilovers off the shelf, but a relatively easy conversion for anyone with a tight budget.
there are also a few options from Leda and Gaz kicking around. Leda i dont rate, they cost twice as much as the performance they offer (you can buy equal dampers from their competitors for half as much). Gaz are decent value for money, but they are cheap, and you get cheap performance. nothing wrong with that, the same can be said for Koni. but id rate the Koni's as a better damper like-for-like.
Great, thats a pretty comprehensive answer, thanks :)
So the best option so far is to keep my Koni's and fit a ground control spring conversion kit. What spring rates should i be looking at? Its a T-bar with about 50 kg removed.
seeing as thouhg KYTII is in bits i too am interested in upgrading suspension bits so any recomoendations as to what i could stick on her would be great..
thatnks for the info..
spring rates are dependant on preference. id recommend starting somewhere around 200/225 for mostly road use and then tailor it from there.
Nik - what is your budget for suspension?
nikwills
20-02-2009, 13:04
Hi Jim,
reading your thread with interest, I have a full set of 4 genuine Toyota manuals for the MR2 AW11 which includes the "Repair manual for collision damage" this contains how to remove and replace all body panels how to attach, overlaps for butt welding and finished dimensions and instructions for measuring.....you live local and I am off work next tuesday I could pop it round for you to flick through and see if it would be of use for you to have a borrow of it when you're ready to start reassembley,
regards Nik Wills
that would be pretty useful!! there are some diagrams on the web at http://opc.mr2oc.com/ that show how all the panels go together vaguely (probably not in the detail of what youve got though), not sure if what youve got is anything like the stuff already on that site under the "Body" section?
give me a shout on monday or something though
nikwills
20-02-2009, 14:30
Hi Jim, will you be on here monday afternoon/evening then? The pages on the link look like scans from the manual I have...Nik
yeh, i check on here a few times a day, depends how bored i am lol
Diesel Meister
20-02-2009, 14:48
Jim, nice project. I watch with interest.
Also, on the topic of suspension what you say does make absolute sense. You can spend a fortunate on the right hardware, then some more on tuning it to the desired compromise (I'm mindful of Chris Harris' £7k set of dampers for his 1970s 911 "ultimate sportscar" project).
But is there realisitcally any coil-over suspension that is off sufficient quality and compliance to be worth, say, £1000-£1500? I'm not wealthy or hugely ambitious (loads of adjustment is only necesary to fine the balance and probably wouldn't be used again) but I might just stretch the debts to get some kit that was top-notch for fast road use and usable for the occasional bit of light (i.e. not timed) track work.
I get the sense I'm asking too much - am I right?
semtexcow
20-02-2009, 15:26
good luck with it jim, thats a power/weight ratio to die for :)
im my old ford days of the 1980s a car was fast if it had 100bhp/ton rotflmao
thats going to be one hell of a beast :eek2:
for £1000-1500 your best bet is still Koni's and G/C coilover sleeves really. unless you can find a set of mk2 Ohlins in good condition, in which case youd have enough money left over to pay for the labourand parts to convert them and give them a service (and revalve possibly)
spring rates are dependant on preference. id recommend starting somewhere around 200/225 for mostly road use and then tailor it from there.
Nik - what is your budget for suspension?
dunno really..about a grand..
there isnt much you can do with a grand past Koni's and ground controls at present
i did some quick maths on what genuine Ohlins would cost. prices would be somewhere in the region of...
Single Adjustable - £3000
2-Way Adjustable - £3500
3-Way Adjustable - £4000
4-way Adjustable TTX (as run on just about every BTCC car) - £11000
prices would include springs, but not top mounts. well beyond the realms of most MR2 owners so far as expense goes! hence im working on something else that should place more in the £1000-1800 bracket (hopefully including EVERYTHING required for fitment)
jeez..im not going professional..!!!
just a nice plug and play coilover with adjustable rate shock will do me..
Hi Jim,
I have been reading a lot of your suspension setup posts recently and have certainly learnt something from you:thumbsup:
I have a Mk1b 3VZ-FE V6 and think the ground control coilover sleeves with konis are looking like the best compromise in terms of value for money for myself, my question is where can I get the ground control sleeves from ? And have you thought any more about the koni revalve/coilover kit ?
Thanks.
£11k? Holy feck!!
theyre the best macpherson strut damper on the market. you most definitely get what you pay for, and youll get at least £11k of performance (e.g. if you spent it elsewhere, you would find less lap time than you would from getting Ohlins TTX46 dampers)
http://www.amortisseurs.pkm-consulting.com/media/grandes/TTX46MTMK2.jpg
tell me that doesnt look like its worth £2500 per corner!! (the reason a set for an MR2 would cost £11k is due to the unfortunate situation of 4 macpherson struts (which cost more than any other damper!) and you would need a grands worth of additional parts to make them fit)
as for V6 suspension options, it depends entirely on budget. if your budget can only stretch to Konis and ground controls then that is the best option available. with the V6 you do have the benefit of additional weight, so you could probably run mk2 Ohlins without revalving, meaning if you found a coilover set (there is a fixed platform version as well) for £200-400 and they were in good condition, you could probably have them on the car for less than it would cost for Koni's and GC's!!
with regards revalving Koni's, it will happen as soon as i am in a position for it to. at present i just dont have the facilities to meet any kind of demand, and id rather not do one or 2 sets of them, find they work awesomely, have another dozen people wanting them, and not be able to fulfill the orders in a reasonable timeframe. it is something i definitely want to offer in the near future, however there look like possibly being better options for not a lot more money in which case the Koni's may then not be as viable (i can still revalve them though for existing owners).
finally, Ground Control sleeves are as far as i know only available from the US. i dont know of any UK or European distributors. and the dollar is strong at present so it makes them not that cheap. might be worth trying to just get the sleeves without springs to save on shipping, then buy cheaper universal coilover springs in the UK for about £28-40 each
s_cleary84
21-02-2009, 12:43
Are these (http://www.ground-control-store.com/products/description.php/II=102/CA=89) the Ground control ones you're talking about?
I understand you need to remove the standard spring seat, but how do these attach to the lower strut case?
yeh those are the ground controls. as for fitting, it varies from model to model. on the MR2 iirc you simply trim the existing spring platform back (but dont remove it) and rest the ground control sleeve on the existing platform, then there are collars that locate it radially. on some models you have to weld a ring on and rest it on the ring (sometimes its better to do that anyway)
Marksman
21-02-2009, 15:08
tell me that doesnt look like its worth £2500 per corner!!
That doesn't look like it's worth £2.5K per corner.
You asked for that :slap:
Very, very nice. But how many parts is it made from? Only a handful I'd imagine. Think of how many precision parts make up say a motorbike engine, you're now justifying paying more for that than a couple of engines...
Nice indeed but 10K nice? Lend me a set and I'll tell you :hidesbehi
Owen.
That doesn't look like it's worth £2.5K per corner.
You asked for that :slap:
Very, very nice. But how many parts is it made from? Only a handful I'd imagine. Think of how many precision parts make up say a motorbike engine, you're now justifying paying more for that than a couple of engines...
Nice indeed but 10K nice? Lend me a set and I'll tell you :hidesbehi
Owen.
130-150 parts per damper, so somewhere around 550-600 precision manufactured parts per set. probably more individual components than an engine. and bearing in mind that engine parts are fairly large, the precision parts in a damper can be as small as a couple of mm in their largest dimension!! when youve got oil flowing through holes that are 2mm in diameter (but not round, they are all sorts of wonderful shapes) being controlled by a precision needle (again only a couple of mm wide), and a 0.01mm intolerance could make a significant difference in damping force and consistency, its easy to see how the cost of the parts is EASILY justified. plus everything is made from aerospace grade material and every critical component gets dimensionally tested before being used. theres a reason why Öhlins dampers are amongst the best in existence. if you saw the machining in the TTX's youd understand fully how they justify their cost
the TTX macpherson dampers are probably the lightest macpherson strut in existence as well. they weigh 3kg EACH. add in a top mount, lower ears and a spring and youre looking at more like 5kg. i reckon the struts on my MR2 weigh somewhere around 20kg a piece assembled, id take a 75% reduction in unsprung weight!! :D
f426YOUNG
21-02-2009, 15:44
Jim - 1 Owen - 0
lol
Marksman
21-02-2009, 18:47
I sit corrected!
Do you have an exploded diagram of something similar Jim? Just interested in seeing the gubbins.
Cheers,
Owen.
I sit corrected!
Do you have an exploded diagram of something similar Jim? Just interested in seeing the gubbins.
Cheers,
Owen.
ive got zillions of exploded diagrams, il sort some pictures out tomorrow. ive got some cut through CAD diagrams as well, but im not sure if they are supposed to be shared so il withhold those.
Marksman
21-02-2009, 23:12
Fair enough :thumbsup: I'd just assumed that a damper was a tube with some holes to squirt oil through so am interested in how much engineering is packed into one. I guess I just like intricate gizmos. :blush:
Owen.
Fair enough :thumbsup: I'd just assumed that a damper was a tube with some holes to squirt oil through so am interested in how much engineering is packed into one. I guess I just like intricate gizmos. :blush:
Owen.
the £50 inserts you buy from Toyota pretty much are. Koni's are a tube inside a tube with a "piston", which is basically just a flat disc with some holes drilled in it, that goes up and down. and then there are check valves to control the flow in different directions, and a preload adjuster to adjust the rebound damping. then youve got a valve at the bottom that controls the bump damping which is another flat disc with holes drilled in it and a check valve.
once you get past the £1000 mark youre into shimmed pistons, which are flat discs with bigger holes in, and then stacks of thin metal shims blocking the holes, and it requires a certain amount of force to open the shims up to allow oil flow, dependant on shaft speed. you tailor the shim stacks to give the force-velocity curves you want, and then there are typically bleed adjusters to adjust the damping. and then it gets a hell of a lot more complex from there!!!
Marksman
22-02-2009, 06:30
Good stuff :thumbsup: Reading that the exploded diagrams probably wouldn't made sense to the uninitiated like me.
Thanks Jim.
Owen.
Jim, ive got those Tokico Illumina shocks sitting here if you fancy dyno'ing them..theyre not brand new but purchased from rosssco a while back..
i havent got access to a dyno at present, otherwise id take you up on the offer now. its top of my "things to buy when ive got £15k spare" list lol
hopefully il have one shortly, along with a few other toys that i need. once ive got a dyno i intend to do some proper research on the available options for the MR2, as well as some other vehicles of interest
ah sorry my mistake chap..i was reading an old post of yours which said you had access to one..
yeh i used to have access to the one at work when i was at ohlins. its probably broken by now, it was knackered when i left and in desperate need of a service. i should have my own one brand new before too long though!
well if you could put together a complete coilover with correct spring rates and decent shocks for a mk1.5 i think youre onto a winner..cos im totally fucked off with researching it all..ive learnt lots and absolutely nothing at the same time..i hate using 20 year old crap and nailing some ali on top of it, guessing spring rates for a car with the [wrong] engine in it..i give up..
:rant:
Marksman
23-02-2009, 06:53
guessing spring rates for a car with the [wrong] engine in it..i give up..
:rant:
At least that's one good thing with the kits though is standard size springs so easily changed.
Owen.
Diesel Meister
23-02-2009, 14:03
The man has a point though :)
I think I'll just go with some adjustable konis for now. Eibach prgoressive rate springs available / worth it? (looking at a Mk1.6)
Diesel Meister
27-02-2009, 14:58
Having spoken to a friend based in the states, I've been warned that Eibach progressive rate springs may not be ideal (sorry for the thread hijack Jim - this may be loosely relevant to what your doing I guess...).
Is it true that the stock AW11 springs are linear front and prog rate rear? This friend was saying he didn't like the feel the of Eibach (prog rate all round) springs on the front, preferring either TRD springs (tad too low) or ST springs (linear front, prog rear and a good off the shelf solution). He reckons coils and camber plates are the only way forward for track-biased performance (chiefly, eradicating understeer), due to the camber limitation on the front of Mk1 (also I'd guessed that the std. spring perches would limit wheel width at the front a bit). This guy has good Auto-X experience (with trophies at national level) with both AW11 and SW20 MR2s.
What's your opinion?
Having spoken to a friend based in the states, I've been warned that Eibach progressive rate springs may not be ideal (sorry for the thread hijack Jim - this may be loosely relevant to what your doing I guess...).
Is it true that the stock AW11 springs are linear front and prog rate rear? This friend was saying he didn't like the feel the of Eibach (prog rate all round) springs on the front, preferring either TRD springs (tad too low) or ST springs (linear front, prog rear and a good off the shelf solution). He reckons coils and camber plates are the only way forward for track-biased performance (chiefly, eradicating understeer), due to the camber limitation on the front of Mk1 (also I'd guessed that the std. spring perches would limit wheel width at the front a bit). This guy has good Auto-X experience (with trophies at national level) with both AW11 and SW20 MR2s.
What's your opinion?
not sure what the springs do as standard. there is so much misinformation floating around on what the standard setups do and dont do that its hard to keep track (people speculate all the time, im yet to see any proof of what the springs do). ive got a damper dyno on the way, and ive also purchased a spring rating add-on for it. so once it gets here i can test the stock springs and see exactly what they do, as well as dampers.
personally i dont much like progressive springs, youve got to do a lot of analysis to find a setup that works, ultimately a progressive setup can be better than a linear spring in some situations. they add a lot of complexity where it isnt really necessary though, id rather work with linear springs most of the time and tailor the handling characteristics with the damping.
so far as what works best, go on what other people say who drive similar cars to you in similar situations. the Eibachs get a mixed review in the US, they seem to prefer ST springs. over here the Eibachs seem to have a much better audience. American roads are pretty nasty on the most part from my experience though, worse even than UK roads, as hard as that is to beleive! plus Americans seem to love having their cars really stiff on spring rate.
if wheel width is an issue then coilovers are the only way youre really going to get around that because youll be using 2.25" or 2.5" universal springs and saving a good inch in clearance space
snowtigger
28-02-2009, 11:34
okay i like all this tech stuff now explain how magnetic dampers work like in the r8.
from wot i gather they use superviscosity fluid with particles of metal to make the fluid thicker or thiner depending on the polarity and strength of the magnet.
okay i like all this tech stuff now explain how magnetic dampers work like in the r8.
from wot i gather they use superviscosity fluid with particles of metal to make the fluid thicker or thiner depending on the polarity and strength of the magnet.
they work pretty much like you say. magnetorheological damper (which is what they are officially called) generally tend to run some form of internal valving, not dissimilar to a conventional damper. they then also have a magnetic field generating circuit built into the piston (the wires tend to come out through the shaft, which is also very convenient for packaging!) which is controlled by a computer. the fluid contains tiny particles of metal (typically iron i beleive) suspended in an oil. if you switch off the magnetic field, the fluid behaves as a newtonian fluid (e.g. a single viscosity, dependant on temperature), the same as normal damper oil. the damper has valving built in, so the damper would essentially run as-is, without the magnetic influence (id imagine this is good from a safety perspective, should the computer fail or the car lose power, etc)
switch on the electromagnetic circuit though and you can alter the viscosity of the oil. there are several ways of implementing this into a useful device on a car. you could have a very simple setup whereby there is a "sports" mode. you press a button, the oil viscosity gets increased by 20%, and youve got stiffer damping all round. thats the most basic form of use, im not sure how the various manufacturers are using their systems.
then there are more complex systems. you could have a system that varies viscosity depending on driving style, not dissimilar to the electronic gearboxes of the early '00's that "learnt" the drivers gearchange preferences and adjusted the shift points accordingly. you could have a system that reacts to how fast the car is going, a system that reacts to steering input and speed (so in a straight line the ride is soft and comfortable, as you apply steering input it reacts to improve the handling). then you could go crazy and have a semi-active system operated by complex algorithms that based its performance off of various sensor inputs, for example accelerometer inputs to gauge weight transfer in the car and adjust the damping to compensate, etc.
there are near-endless possibilities depending on what the desired outcome was. i know that Ferrari employ MR technology on their 575's. the dampers are made by Sachs. i beleive they have a "sports" switch, but what exact effect the MR technology has on the damping as a whole i dont know. manufacturers arent hugely forthcoming about their uses of advanced technology, especially when it is a long way from becoming mainstream!
so far as motorsport use goes, i dont see it happening, probably not ever. so its unlikely il ever have much of a dealing with this technology on my current career path. the prospect for massively increased cornering speeds pretty much destroys the chances of ANY technology like this ever seeing use in top end racing. its the reason they banned active suspension back in the early 90's. the dangers of taking corners at speed are too risky, even with modern safety standards. cars can already generate 3+ lateral G's in cornering, the forces acting on a human neck at those speeds are pretty intense. increase the lateral acceleration by 20% and introduce contact mid-corner from another car and you might end up seeing people snapping their necks during F1 races.
s_cleary84
01-03-2009, 10:16
Pretty sure the HSV GTS (http://en.wikipedia.org/wiki/HSV_GTS) uses magnetorheological dampers too
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions Inc. All rights reserved.