Need some help from the track gurus here.
My 1997 M3 track car came with Wilwood 6 piston front, 4 piston rear brake calipers utilizing e46 M3 rotors all the way around. I believe it's from UUC and was installed a couple owners ago, been on the car for 4-5 years. I like the feel of the brakes on the track, but am debating going back to stockas there are more people with spare stock parts at the track than Wilwoods.
Last November the front calipers stuck causing me to miss a track day. I took the winter to pull all 4 calipers off the car, ordered new Wilwood caliper piston seals + the new pistons themselves (a few were scratched so I replaced the lot), and reassembled everything with fresh HT10 pads. Was just at Road Atlanta with the BMW club on March 3-4. For the Saturday sessions the setup felt great, no complaints. However on Sunday I noticed the drivers side pad on the outside was worn much more than the rest. For the last 2 sessions on Sunday I was having real issues with the caliper getting stuck on track. The problem seemed to come and go, but was there more often than not. By the drive home the drivers side caliper was locked up (cannot turn the wheel by hand).
Upon inspection (see pictures below), its obvious the outside of the driver side caliper is sticking - that's the bottom pad in the picture. Looking at the other calipers, none are stuck and the pad wear inside/outside is even. Wear seems good as well on the other pads, about 75-80% life left. (12.5mm thick now vs. 16.5mm new).
Anyone ever seen this before? On a freshly rebuilt caliper, what could cause this sticking? I've heard stuck brake lines can cause sticking caliper issues, but that would be manifested on both inside/outside of the caliper right?
Thanks for any help or suggestions!
20180311_104713.jpg
Block or restriction in the cross-over line? The pad retainer shims not bent or damaged? Is the bracket ok, not bent in any way to cause a bind? As a last resort, you could take them completely apart (split the halves) and ensure there is no dirt in any of the passages ... maybe soak in brake clean for a bit? Just ideas for you. We've run these on 2 cars without any sticking issues, and one set hasn't been rebuilt in years.
+1 to all the above.
I have the same setup OP has (6 pistons FR, 4 Pistons RR). I only rebuild them every 2-3 seasons and even at that they dont need it, its just PM.
I have to think you have some blockage.
Might try diassembly and an ultrasonic bath?
That said,,, I never let my pistons get that far out of the caliper. I have a set of shims I use if I am going to run pads down past 1/2 thickness to keep the pistons tucked into the calipers.
jimmy p.
88 E30 M3 Zinnoberot - street
88 E30 M3 Lachsilber - SCCA SPU
87 E30 M3 Prodrive British Touring Car 2.0 Litre
04 Ford F350 - V10
06 Audi A3 Brilliant Red / 2.0 / DSG
The pad retainer shims were a little loose when I rebuilt the calipers, so I very slightly bent them so they would stay hooked into the caliper. Those are mainly just to protect the aluminum caliper and help with squeel/rattles though I thought, not actually holding it?
I'll take a look at all the brackets, but pretty sure they are all square.
Do you run your pads all the way down to the backing plate without any kind of pad spacer? I read that maybe the pistons being pushed far out of the bore can result in sticking vs when the pad is new and pistons are more retracted.
Any other tips or things you do on your setup to keep it functioning properly? pad rotating etc? are you on the UUC setup?
Last edited by 5speed300; 03-11-2018 at 02:38 PM.
Todd at TCE, but i think other people sell them now.
http://www.tceperformanceproducts.com/service-parts/
jimmy p.
88 E30 M3 Zinnoberot - street
88 E30 M3 Lachsilber - SCCA SPU
87 E30 M3 Prodrive British Touring Car 2.0 Litre
04 Ford F350 - V10
06 Audi A3 Brilliant Red / 2.0 / DSG
Well, seems my luck with these calipers has continued. Accidentally shot a caliper piston from one side into the other and dented where the piston slides into the caliper (pictures below). Can't get it straightened out, so going to have replace the caliper. Trouble is they upgraded the Billet Narrow Superlite 6 design, so I think I'd need to replace both fronts with the new style so I don't have a different generation on each side.
Going to call UUC tomorrow and see if they have more of the 6 piston calipers in the older style. Other option may be to convert the front to the 4 piston caliper which is significantly cheaper.
-1 new 6 piston is around $380
-2 new 4 pistons are around $376, need to confirm the UUC mounting brackets for the 6 piston kit also work for the 4. Upside is I'll get to use the 20mm pad rather than 16.5mm. Only potential negative would be pad taper since the 4 pistons don't have the differential bore design.
Anyone with experience running the 4 pistons up front? Any other options I'm overlooking (maybe ditch the whole thing and go another route)?
Last edited by 5speed300; 03-11-2018 at 05:09 PM.
You want to get away from those oddball narrow body calipers anyway.
The full size Wilwood Superlite pad shape is the most common pad shape in all of motorsports.
Whatever brake pad brand / compound you are looking at,,, that pad shape will be the least expensive.
If you can fit full size Superlites I would do it. Those narrow body units are oddballs to buy and then buy consumables for.
jimmy p.
88 E30 M3 Zinnoberot - street
88 E30 M3 Lachsilber - SCCA SPU
87 E30 M3 Prodrive British Touring Car 2.0 Litre
04 Ford F350 - V10
06 Audi A3 Brilliant Red / 2.0 / DSG
ScotcH, jimmypet, are you guys running OEM E46 rotors as well? I'm looking to move to some sort of fixed caliper setup that uses an OEM rotor. Would you recommend this approach? What brackets are you using? Lug mount calipers?
I'd really like to find a radial mount bracket that'd allow me to run a full width Superlites on an E46 rotor. dreams...
I run the 4 piston Superlite calipers with Massive Brakes floating rotors up front on my racecar with stock calipers rear. They work great and the best part is the pad selection (and better price as compared to OEM or otherwise). They do taper somewhat, but so do 6 pistons from what I have seen on friends cars. With the 20mm pads you can then use, it will be better even if they taper. You could always contact Lee at Massive for some adapters or otherwise as well. Not sure if those UUC adapters are lug are radial mount. If lug mounted, they would probably work or just need a hole or two drilled.
I just purchased two Superlite 4 Piston calipers from UUC. They bolt right up to the existing 6 piston brackets and lines I have. Much cheaper than the 6 piston replacement caliper as well.
For those wondering, the UUC kit uses Lug Mounted calipers - does this make an appreciable difference in performance vs. Radial Mount?
Excited to see how they do, and glad to have the same 7420 pad shape all the way around now.
Last edited by 5speed300; 03-12-2018 at 03:48 PM.
Mine are a one off, custom build on an E30M3 SCCA Super Production Under race car.
Radial mounted fronts, Lug mounted rears. 11.75 x 1.25 directional rotors FR, 11.75 x .810 straiht vane rotors rear.
My setup is very similar to a setup Lee Vuong sold through Massive which he called the Rally Kit.
Honestly,,, just me,,, I cant imagine why you would want to run an OEM rotor.
Aftermarket race rotors will wear longer, shed heat better and probably lower your operating costs after the buy in.
My custom brake setup "buy in" recouped in 2 seasons vs. what I was spending chewing through OEM BMW rotors and OEM pad shape race brake pads.
Aftermarket race brakes can actually reduce operating costs as long as you are not married to using tippy top of the line billet Performace Friction or Alcon gear.
jimmy p.
88 E30 M3 Zinnoberot - street
88 E30 M3 Lachsilber - SCCA SPU
87 E30 M3 Prodrive British Touring Car 2.0 Litre
04 Ford F350 - V10
06 Audi A3 Brilliant Red / 2.0 / DSG
Totally, agree, aftermarket rotors are way nicer. You save weight, and they will last a long time. Not as cheap as Chinese OE, but the coleman/wilwood discs are not bad. We run 330x30mm disks: http://www.wilwood.com/Rotors/RotorP...temno=160-8165
I had a Stoptech kit, but sold it when rotors got to be $350 a piece. That's just silly.
The stock brake rotors seem to have enough thermal capacity. Slightly bigger E46 330 rotors or even E46 M3 rotors would offer even more for way less money that BBK rotors.
What I'm after is a solution to my soft squishy inconsistent pedal that has plagued me with every BMW i've ever had. The Stoptech felt an worked great. I want that for cheap. :-D
Dan
Agreed 100%.
Did you look at if anyone else's rotors bolt pattern fit your hats?
For example my Gruppe A car was raced in the UK, so it was fitted with all UK born AP brake components.
A 330mm AP rotor is stupidly expensive for a car that is not racing for a paycheck, but Coleman rotors for that are a fraction of the cost of APs and for my weekend warrior ass work just as well.
My Club Racer is all Wilwood 11.75 x 1.25 which are cheap already,,, and if I wanted to there are loads of crazy cheap options in that size because its a very popular size with the roundy rounders.
If you like the brakes, see what alternatives may exist outside of the Stoptech rotors.
jimmy p.
88 E30 M3 Zinnoberot - street
88 E30 M3 Lachsilber - SCCA SPU
87 E30 M3 Prodrive British Touring Car 2.0 Litre
04 Ford F350 - V10
06 Audi A3 Brilliant Red / 2.0 / DSG
The race shop I work with has several of their clients running Stoptech systems, and he is very positive about how well they perform on the race cars. He can get rotors (332 by 32 mm) for about $190 delivered (not sure from where, maybe Coleman). I had some concern on the rotor cost before, but at under $200 it wouldn't really be a problem.
I have a Stoptech rear E36 kit for sale if anyone is interested... My reason for wanting to sell is desire to share the Wilwood pad shape between front and rear, using a Massive rear set up. If the Stoptech kit doesn't sell I'll just use it, and just not be able to have common pads.
Quick follow-up question. I may go ahead and replace my front stainless brake lines while I'm putting the new calipers in. They are a few years old and figured it's easy to do just in case there was something in the lines themselves causing my lockup issue.
I'm assuming I can't buy normal stainless braided lines for an e36 m3 and expect them to screw into the Wilwood caliper? Is there some kind of adapter needed on the caliper to accept the factory replacement stainless lines? My current setup has stainless braided lines that screw directly into the wilwood caliper without an external adapter. Problem is I don't know if they are a special set of lines that was made for the kit. Would be nice to utilize factory lines just in case something happens at the track - easier to find replacement e36 m3 lines than some kind of special wilwood line.
Wilwood uses 1/8" NPT fittings. You can get 1/8" to Metric, but the better route would be to use -3 AN female on the caliper side, and female metric M10x1.0 (BMW size) on the line side. That's a pretty easy line to make up for any hydraulic shop. Wilwood actually sells a set that will fit e36 and e46 directly, in exactly that configuration
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