Vented rear disk on an e36 compact?

[mohaughn]

PS! Please apologize my bad english. Please also forgive my use of SI-units (1 inch=25.4mm)

I would never have known you were not an native english speaker. Your english is pretty good in my opinion...

With bp-10 up front (.42) and Hawk Ceram. rear (.52): Bias 67.16%
With bp-10 up front (.46) and Hawk Ceram. rear (.52): Bias 69.14%

That might explain why I went through a set of rear calipers so quickly. They already had about 15k miles on them when I switched to this brake system. I didn't want to run the stock rear pads so I had them throw in a set of the hawk ceramic pads. So the mismatch in the bias is my fault. But I've not had any issues with the rear wheels locking up before the fronts. In fact, I've not been able to lock the wheels up at all on clean dry asphalt.

You could also look into the stage 3 kit with the 6 pot up front with the wilwood 4 pot in the rear. I think it comes standard with bp10's front and rear. And they seem like nice pads, I've not had any fade with them. I'm running motul brake fluid.

I do have to ask though, do I need to be concerned when I am running the track pads that the coefficient goes up so high once the pads get hot? Will the transfer of bias to the front of the car really be that noticable? My thought was that as long as I have a nice stiff suspension up front the extra bias up front may cause quicker wear on the pads and rotors up front, but the stiff shocks would keep the car from nose diving.

[KIRASIR]

Your rears look like the regular cross-drilled solid disks.

Cross-drilled is not the same as vented.

Originally Posted by Mendi3

Front:
E46 (330i) calipers with vented discs from Bavarian Autosport and mintek pads.

Rear:
Stock calipers with vented discs from Bav Auto and mintek pads. Bav Auto makes the vented discs for the stock 318ti.

[KIRASIR]

Originally Posted by e36 323ti

2) Neither Brembo nor Willwood make bolt on rear brakes for the 'ti (at least to my knowledge based on the contact that I have had with them).

No, but Brembo/willwood calipers can be found relatively cheap on ebay and skillfully combined with custom carriers.

[mohaughn]

Yeah. The photos at bavauto show that they are selling vented rotors, but I don't see how that would be possible. The lateral area of the rotor would be tiny and you would go through them in no time at all. And since those rotors are actually drilled, and not cast with the holes in them I'd be hesitant to run them.. I may end up getting the slotted ones for the rear and call it a day.

[e36 323ti]

Originally Posted by mohaughn

You could also look into the stage 3 kit with the 6 pot up front with the wilwood 4 pot in the rear. I think it comes standard with bp10's front and rear. And they seem like nice pads, I've not had any fade with them. I'm running motul brake fluid.

I have now analyzed both the stage 2 & 3 kit. I have realized that maybe a 6 pot caliper would suit me, since I then do not need a spacer on my track wheels (M double spoke 68). It require spacers on my street wheels though. Also it seems like the 6 pot caliper is in one version only when it comes to piston sizes. With stock rear I would then have got 77.3% front bias, which I think is too much. By going for 276x19 vented rear, e36 325 rear caliper (Ø36mm) and master cylinder (Øf/Ør = 23.81/22.2mm) from e46 325 I would have bias 72.3%, which is pretty close to stock.

Regard the stage 3 kit, it is delivered with 385mm rear disk only and 4 pot caliper, at least how I interpret the information. Since the 6 pot caliper is one version only, this leaves no choise but the smallest 4 pot caliper. This gives a bias of 68.4% which I think is a bit too rear biased.

Originally Posted by mohaughn

I do have to ask though, do I need to be concerned when I am running the track pads that the coefficient goes up so high once the pads get hot? Will the transfer of bias to the front of the car really be that noticable? My thought was that as long as I have a nice stiff suspension up front the extra bias up front may cause quicker wear on the pads and rotors up front, but the stiff shocks would keep the car from nose diving.

All my views is based on theory, and so far I do not have any real experience. But I see that the theory fit conseptually with what people reports. These guys (http://www.europeancarweb.com/projec..._wheels_tires/) swapped the 280x10mm rear solid disk with 276x19mm vented and used the Ø38mm caliper from the e36 328 to move the front bias 2% to the rear on an e36 325. This was done in consultation with StopTech. Their results shows stopping distances of 123ft (37.49m) in average from 60-0 mph. I do not have data for the e36 325i with stock setup, but an e36 320 has a stopping distance of 39.4m and a 328 has 38.2m from 100-0 km/h (62-0 mph) (at least according to: http://www.movit.de/rahmen/stoptbl.htm), so the data is not 100% comparable.

Also StopTech in [1] claims that if the car have correct bias, the pads should be worn out relatively equally front/rear, so your rear pad wear may indicate too much rear bias for your street setup? But that could possibly be due to different pad material as well?

Regard your track pads I used the wrong max. friction coeff. in my previous calculation. The correct should be:

With h-comp. up front (.54) and Hawk Ceram. rear (.52): Bias 72.45%
With h-comp. up front (.64) and Hawk Ceram. rear (.52): Bias 75.71%

Honestly I do not know if approx. 3% increase in front bias is noticeable, maybe only by measurement (but 10 inches later braking a lap, makes almost a car length in a 10 lap race)?

You are ahed of me - you have the opportunity to do real test. I am not going to be in that position until May next year, so until then I am only a theoretician

It seems although like UUC have selected your caliper to maintain stock bias, and I would have tried to keep it like that by using pads with the same friction coeff front as rear.

[1]: Brake Bias and Performance - Why Brake Balance Matters http://www.stoptech.com/tech_info/wp...formance.shtml

[e36 323ti]

Update: According to UUC's web pages neither the stage 3 kit nor the 6-pot Wilwood caliper can be delivered to the ti'

[mohaughn]

Since you are out of country I can call them and find out if they have plans for the stage3 to fit a Ti, or what the deal is with the 6pot not fitting on the front. Or you can just email them, they have been pretty good about getting back to me quickly when I email them with questions.

[e36 323ti]

Originally Posted by mohaughn

Since you are out of country I can call them and find out if they have plans for the stage3 to fit a Ti, or what the deal is with the 6pot not fitting on the front. Or you can just email them, they have been pretty good about getting back to me quickly when I email them with questions.

It would have been very much appreciated if you could have given them a call According to their web site, they do not answer emails. I have emailed them, but I do not expect an answer because of this. Also their email address is hard to find - I have used the emailaddress distributed with their regular mail letters.

When it comes to the 6-pot caliper, I guess the reason why is that the car would then be too front biased.

[pdxmotorhead]

I take care of several race cars with brake systems
similar to the TI and none of them stress the rear
brakes very much.

Our 88 200 SX wears out 3 to 4 sets of front pads to
every set of rear pads. With weight transfer at track
speeds its easy to get to much rear brake. Same with
a old E30 I work on occasionally. We run Hawk Black
or Panther Plus pads. Nothing fancy.

Also in my opinion I don't like the ceramic pads.
I find they have inconsistant feel and havn't
really liked them in any car I've driven with them.

Wilwood and Brembo both publish some data
that implies there is a upper limit to the brake
sizing that you hit based on car weight and tire style.

Good luck!
Dave

[e36 323ti]

Originally Posted by mohaughn

Since you are out of country I can call them and find out if they have plans for the stage3 to fit a Ti, or what the deal is with the 6pot not fitting on the front. Or you can just email them, they have been pretty good about getting back to me quickly when I email them with questions.

I have not managed to get in contact with UUC via email

I was also curious of the dim. of the 325mm rotor. According to their web one can choose between 325mm floating or non-floating rotors, where the floating rotor is an e46 BMW M3 rotor. That makes it 325x28mm (at lesat for an Euro spec M3 according to the ETK).

But what about the non-floating rotor? According to this info. (http://www.uucmotorwerks.com/PBC/weight.htm) the rotor in the example is 325x32mm. Is this a typo or is it the non-floating rotor, which then have to be thicker then the floating M3 rotor?

For me the stage 2 kit starts to sound appealing, specially considering the weight saving. Maybe I should skip the rear vented project and go for a UUC-stage 2 with stock rear

[e36 323ti]

Originally Posted by mohaughn

front-
4 piston forged billet superlite caliper(120-7477)- http://www.wilwood.com/Products/001-...-FSL/index.asp
bore size- 1.38" 35.0 mm
disc width- 1.10" 27.9mm

325mm rotor

Another question:
I have got some indications that some people are not happy with the Wilwood calipers. They claim that the caliper flexes under hard braking. As far as I can understand they are talking about the Superlite II and Dynalite calipers. The symptoms is a soft pedal and bad brake modulation. Also there is a suggeted fix for the Superlite II caliper, which I think is implemented in the Forged Billet Superltie caliper (the bolt on the top of the caliper).

Any comments?

[mohaughn]

Originally Posted by e36 323ti

Another question:
I have got some indications that some people are not happy with the Wilwood calipers. They claim that the caliper flexes under hard braking. As far as I can understand they are talking about the Superlite II and Dynalite calipers. The symptoms is a soft pedal and bad brake modulation. Also there is a suggeted fix for the Superlite II caliper, which I think is implemented in the Forged Billet Superlie caliper (the bolt on the top of the caliper).

Any comments?

I've read the same things. I've not noticed any brake modulation or soft pedal with my setup. The pedal feel is actually almost identical to what it was prior to doing the brake upgrade. If anything the pedal is a little bit stiffer, but I attribute that to fresh brake fluid and the SS lines. I found a corvette site where somebody switched from the superlite II to the forged superlite and liked it much better. I've only been running them for about 4 months so I don't have any long term experience with them yet.

My understanding is that the superlite II caliper is not forged but billeted, and does not have the same type of bracing across the top of the caliper. I don't even think they sell the caliper that people had problems with.

BTW- UUC has been closed. Their website says a truck took out the power to their building so they are closed until they have power.

Is this a typo or is it the non-floating rotor, which then have to be thicker then the floating M3 rotor?

My guess is that it is not a floating rotor, I'm not really sure about the dimensions. The floating e46 rotor they sell is the Euro E46 M3 rotor. This is what I bought with my kit.

e36- Check your PM's. I talked to someone at UUC this morning and got an email address that they will respond to. They said they would be happy to answer any questions you have.

[e36 323ti]

Originally Posted by e36 323ti

I was also curious of the dim. of the 325mm rotor. According to their web one can choose between 325mm floating or non-floating rotors, where the floating rotor is an e46 BMW M3 rotor. That makes it 325x28mm (at lesat for an Euro spec M3 according to the ETK).

But what about the non-floating rotor? According to this info. (http://www.uucmotorwerks.com/PBC/weight.htm) the rotor in the example is 325x32mm. Is this a typo or is it the non-floating rotor, which then have to be thicker then the floating M3 rotor?

It was a typo. They have corrected it now (should be 325x28mm)

[mohaughn]

Cool. I'm glad they were able to answer your questions. I think you'd probably be happy with the kit, for the price I don't think there is much out there that is a better value.

[mohaughn]

I was maxed out on the attachment size, just bought site supporter, so here is a wheel/brake shot in my gallery.

http://www.318ti.org/gallery/showpho...o=3502&cat=717