View Full Version : ST185 caliper rebuild - daft questions from the mechanically inept
Hi,
Just started the refurb of my ST185 single pot calipers but have a few (probably daft) questions as to how to progress.
Willing to accept obvious answers as spannering is not really my strong point :shhh:
Have dismantled one of the calipers and found the guide pins/runners looking pretty scored and pitted like this:
http://i142.photobucket.com/albums/r89/Gary_H/ST185%20single%20pot%20calipers/DSCF0334.jpg
http://i142.photobucket.com/albums/r89/Gary_H/ST185%20single%20pot%20calipers/DSCF0333.jpg
Does this mean they're fooked or can I just polish the scoring out ?
I'm also wondering how to prevent any sh*te from getting in the runner/piston bores and bolt threads when I wire brush/wheel the rust off the caliper ? Just stuff a rag down there or replace the bolts where possible ?
Atm I've left the piston and it's seal in place as it looks like a pretty good way of keeping the piston bore clean whilst sanding the rust off, good idea or not ?
Aware this kind of buffoonery doesn't qualify me to even hold a grinder :hidesbehi - but hey, got to start somewhere :blush:
Cheers - Gary
keri-WMS
24-02-2007, 16:59
Hi Gary - they look well past it to me, trouble is they'll attack any new bushes you might fit for them to run in... You could get them turned down slightly in the middle section ONLY, but then you'll have too much slack in the caliper.
I'm sure Toyota can supply new ones along with new piston seals and slider/bushes?
hello gary .. brakes international usually supply rebuild kits with guide pins included, i know mrT do a good deal but they dont usually' supply the pins, you can try them etc i'm not 100% on that. brakes international are generally more well known for supplying kits with guide pins. although, i might be abled to sort them out a tad with some diamond polish and mega rpm's if you can bring them round
when cleaning the caliper, strip it totally, dont worry about the bores getitng dirty, you really need to get them apart completely, then when finished wash thru with brake cleaner or brake fluid etc. a rebuild kit will come with new piston seals and clips etc. mate if you want to come over and need a hand one saturday its n/p you know where i am most weekends !.
Cheers Adam.
Unfortunately I've already ordered the caliper refurb kit from Mr T - without guide pins :shifty:
Will check the price of new guide pins from Mr T, existing ones are pretty deeply pitted and I'm concerned about taking a chance where brakes are concerned.
Have yet to strip the other caliper, maybe it won't be as bad :pray:
Cheers - Gary
try brakes international for guide pins on their own aswell, if you cant get the pins.. bring them round to me, i'll sort them out
I think i've fluffed up, thought my brakes were gonna be single piston, turns out they're twin pistons.
Is it the same refurb kit?
i wouldnt have thought so olber, they will be smaller pistons, needing smaller seals and clips etc, cancel the kit matey or sell it here, it'l go..
try brakes international for guide pins on their own aswell, if you cant get the pins.. bring them round to me, i'll sort them out
Cheers mate :thumbsup:
Had a look on the BI site. Looks like the pins only come as part of the caliper kit ( which incidently are £26.27 inc VAT per side - Mr T kit was £42.30 inc but that does both sides - but has no pins, as previously stated by Adam ).
Dismantled the other caliper last night/this morning (after getting back from the pub :beer:) and the other two pins seem fine. I'm missing one of the brake pad clips as well as some of the anti-squeal shims - Toyota parts diagram for the ST185 says there should be three per caliper. Are the shims necessary ?
Anyone got any of these clips (the larger ones) or is it another phone call to Mr T ?
Cheers - Gary
ps HTF do I get the caliper pistons out without damaging them ? they seem pretty firmly in there !
soak the piston in wd40 to help out, makes sure seals are off, wrestle it out.. somehow lol .. all i can say is dont damage the bore wall or piston diameter.. try turning it by hand and pulling..caliper needsto be in bits for this. i probably used a blunt screwdriver under the sealing lip of the piston and levered it up.. but i was very careful and slow.. and held the caliper in a vice ...and have the facility to repair any nicks at my work place.. swiss files / lathes / polishing compounds. just careful thats all.
keri-WMS
25-02-2007, 14:03
People use air lines to blow pistons out but that's a tad....risky! Maybe sacrifice (cut up) an old brake hose and connect it up to a car FOOT pump via a bit of thick rubber/plastic pipe/hose etc with some small jublyclips to seal if off? Won't need to hold a lot of pressure unless it's WELL stuck and that way you won't fire the piston any anyone!!!
BTW, mineral oil/grease attacks the types of rubber they use for brake calipers seals so if you use oil get it WELL clean with spirits etc..... :eek2:
Cheers guys.
I'll be going in to Mr T tomorrow to collect my caliper refurb kit ( on the way back from picking up the porker from the garage :jump: ).
So, will I need to get some anti-squeal shims whilst I'm there ? do I need them or does copaslip do the job on its own ?
i havent used shims to be honest. it totally slipped my mind when rebuilding. perhaps some copperslip will suffice as you say. or pick some up from mrT if he sells. i dont think any came with the optifit pads.
millentubby
25-02-2007, 21:31
soak the piston in wd40 to help out, makes sure seals are off, wrestle it out.. somehow lol ..
I'm doing my ST185 single pots right now (just finished painting...seal kit coming soon!) and my pistons were well and truly wedged in. I used an air line and popped them out (eventually!) with that. Wrap the piston in a oily rag to stop brake fluid and pistons flying everywhere and give it some pressure. Saves any damage occurring from trying to prize the pistons out.
Olber - if you've bought the refurb kit give me a bell - will take it off your hands :)
Oh, and asked for a price on a fitting kit in Mr T the other day....jnr parts monkey (clueless!) said it could be up to £60 just for the fitting kit!!!! pmsl
Marksman
25-02-2007, 22:33
I used an air line to blow them out, but not an airtight seal. ie. use a blow gun but just lightly press it to the input letting a lot of the air escape round the outside, then just press harder until the piston pops out. A block of MDF or something soft for it to slam into isn't a bad idea either.
Oh and if anyone has a set of 185 single pot seals going spare I'd certainly be interested :whistle:
All the best,
Owen.
I ordered it through my mate who's a parts guy, have told him to swap it but if it arrives anyways i'll let you know MT.
Anyone know the part.no for the twin piston refurb kit?
millentubby
26-02-2007, 11:49
not sure on part number but it'll be part of the ST165 parts catalogue. HTH
Anyone got the Toyota EPC that could check this for me?
Tried GT$OC to no avail as of yet.
Cheers,
Olie
Ok - got one piston out with a foot pump attached - took quite a bit of pressure to force it out, over 100psi.
Arrggh - the other piston is totally stuck, it's moved a very small amount but now won't budge - over 120psi on the foot pump gauge >:[
I've put some oil around the piston and left it to soak overnight - hopefully this'll free it up enough for the footpump to work.
Marksman
28-02-2007, 20:20
Can you push it in a bit, say with a G-clamp, just to unstick it, and then push it out with air?
Owen.
Can you push it in a bit, say with a G-clamp, just to unstick it, and then push it out with air?
I've tried tapping it back in (with a block of wood over the piston) but I'm a bit worried about knocking it not-square and jamming it more.
I'll give it another go after the oil's soaked in a bit and then try the G-clamp idea.
Yay :jump:
Gary: 1 Stuck Piston: 0
Cheers everyone who replied :thumbsup: A combination of oil, pushing it back with a G-clamp and the footpump loosened it.
Unfortunately I think that's where the good news ends >:[
http://i142.photobucket.com/albums/r89/Gary_H/ST185%20single%20pot%20calipers/DSCF0340.jpg
http://i142.photobucket.com/albums/r89/Gary_H/ST185%20single%20pot%20calipers/DSCF0339.jpg
Looks like someone has given the piston a hefty whack at some point. The lip is sloped off and this has made the circumference slightly eliptical :banghead:
I assume this can't be rescued and is toast ?
Marksman
01-03-2007, 06:42
Bugger!
New one from brakes international is about £15 I think.
All the best,
Owen.
gary, bring it to me matey, i'll reface it until it cleans up, and re-dress the side / check it over, won't cost you a single bean mate. its n/p
gary, bring it to me matey, i'll reface it until it cleans up, and re-dress the side / check it over, won't cost you a single bean mate. its n/p
Cheers for the offer mate but I ordered a new one first thing this morning :doh: ! Do you still have that set of standard caliper bolts I could buy off you ?
Ok - got to clean up the calipers for painting now.
I want a smooth finish (oops another perfectionist) , presumably that's just achieved by sanding it very smooth before painting ? What grades of wet and dry should I be using once I've got all the rust off ?
Can it be 'too' smooth ? ie affect the ability of the paint to adhere properly :hmm:
Btw can you tell I don't do this sort of thing very often :blush: ?
ah shyte! wished I had got to you sooner,
all that face does is sit against the pad, and all the side face does is...... nothing.., it sits in fresh air.. at most helps hold a rubber seal. so if I re-dressed to 0.02mm under or 0.5mm under it wouldn't make a difference, remember for future guv.
keri-WMS
01-03-2007, 11:01
The very best way would be to get them bead blasted (grit might be too rough) then get the outsides polished, then (quickly) get them plated again!
= Mirror finish! (£££) Or get it "black chrome" plated...
There's also a funny thing where they "flame" the plating on, I don't know much about it though other than it works quite well and might be cheaper.
As for getting it smooth with colour I wonder about powder coating? Not sure about it's resistance to heat though.
If you paint them at home one of the best things is spray-can hammerite - but it takes a long time to cure (you can bake it hard in an oven!). You are almost 100% guaranteed to get a nasty finish if you use a brush...
Hhatever you do, getting some plating on (even under the paint) will stop/slow the rust's return.
superchargedsam
01-03-2007, 11:05
powder coating is melted on to it at about 200degrees for 2 hours so think it would happily withstand brake tempts but then I have no idea how hot they "can" get but was under the impression it wasnt approaching 200degrees!that said I like red hot glowing discs on the rally car pics so guess they do get "quite" hot after all!
ah shyte! wished I had got to you sooner,
all that face does is sit against the pad, and all the side face does is...... nothing.., it sits in fresh air.. at most helps hold a rubber seal. so if I re-dressed to 0.02mm under or 0.5mm under it wouldn't make a difference, remember for future guv.
Will do :thumbsup: - my fault for getting up so early in the morning ;)
You are almost 100% guaranteed to get a nasty finish if you use a brush...
So, even if I prep it well, brush painting it will make it nasty again - :hmm:
I thought most plating processes involved chemical dips and then electro plating, which would plate the entire surface (including threads and bores etc) or not ?
Trying to keep the costs sensible - otherwise I may as well have ordered the entire WMS kit off this 'Keri' bloke lol
keri-WMS
01-03-2007, 11:33
So, even if I prep it well, brush painting it will make it nasty again - :hmm:
I thought most plating processes involved chemical dips and then electro plating, which would plate the entire surface (including threads and bores etc) or not ?
Trying to keep the costs sensible - otherwise I may as well have ordered the entire WMS kit off this 'Keri' bloke lol
L o L, I better shut up! :hidesbehi
L o L, I better shut up! :hidesbehi
Only joking mate. Btw the ST185 discs and Redstuff pads turned up yesterday - cheers, they look great.
Anyone got any tips for achieving the best possible finish if I 'do' brush paint ?
superchargedsam
01-03-2007, 11:49
engine laquer can come out quite smooth if your careful and seems quite hard wearing!
Just an idea
keri-WMS
01-03-2007, 18:48
engine laquer can come out quite smooth if your careful and seems quite hard wearing!
Just an idea
Good point, particularly daft I didn't think of it given I've just been using some to make an engine I'll be selling (niiiice tuned ford xflow) look the part - British Racing Green of course!
Expensive stuff though.... (£30 per tin rings a bell)
superchargedsam
01-03-2007, 19:23
Good point, particularly daft I didn't think of it given I've just been using some to make an engine I'll be selling (niiiice tuned ford xflow) look the part - British Racing Green of course!
Expensive stuff though.... (£30 per tin rings a bell)
hmmm god knows what I have then as it was about £6/tin got one tin from halfrauds and one from local factors and both seem the same, did my rear calipers in it and seems ok as only prep was a very quick bead blast and I aint no skilled painter or owt! perhaps the stuff you have is better again!
keri-WMS
01-03-2007, 19:45
hmmm god knows what I have then as it was about £6/tin got one tin from halfrauds and one from local factors and both seem the same, did my rear calipers in it and seems ok as only prep was a very quick bead blast and I aint no skilled painter or owt! perhaps the stuff you have is better again!
Gowd knows. I got mine years ago! I did notice on another occasion that Halfords "caliper paint" smells and behaves like hammerite... :idea:
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