Attn: Track Ti's...what pad combos you running?

[Cali330ti]

I'm running M3 front setup w/ some surprisingly good bite brembo sport pads. Stock rear ti w/ Hawk HP+. Through me doing an S50 swap I've lost ABS. No ABS light but I don't care anymore....who needs silly ABS in a track car anyhow? Problem is that once the brembo's warm up I get full front lock way before the rears. I'm hoping I can combat this w/ some different pads. Thoughts? Suggestions?

[mohaughn]

You want the fronts to lock first... The rears locking first would be a very bad thing, and would probably throw you into a spin...

Pads are not going to change the fact that the fronts are locking. If you run a pad with a higher level of friction, the fronts will just lock up even sooner. This is a big reason why people don't recommended true race pads unless you have a good feel for threshold braking. I'd work on better braking technique, and learning to feel out the threshold where the brakes are locking... The rear in our cars with stock bias only does about 29% of the stopping.

Usually a street pad will drop in friction as they heat up, race pads will rise slightly to a certain level and then maintain friction levels.

I have no ABS, and I rarely lock the tires under braking unless the track is wet, or I'm really pushing it and brake late, which I view as a mistake, not a shortcoming of my brake setup...

ht10's up front and hp+ in the rear, abs pump disabled.

[1996 328ti]

Too much pad on the rear makes the car more twitchy.
I'm running Carbotech XP11 up front and XP8 in the rear.

I do have ABS and rarely get into them.
Perhaps the RA1s and track pads have something to do with that.

[Cali330ti]

I didn't plan on higher friction pad up front just on the rear. Gonna check temps and see if the pads front and rear are coming up to proper temp levels for the pads. I know I don't want the rears to lock up first...wasn't going for that. I have Azenis RT615's so they aren't R-comps or slicks but fairly decent rubber. I think there might be something else going on....air in the lines or in the abs that's hard to get out.

[mohaughn]

If your ABS pump is not firing it shouldn't matter if there is air in the pump as the valve never opens...

Air in the lines would also cause a "smushy" pedal feel as the brake temps increase it allows more compression of the hydraulic fluid/air mixture without actually moving the brake pistons. Which would make it much harder to lock the brakes, not the opposite.

If your only complaint is that the front wheels are locking up, I would say it is braking technique. Going to larger brakes is not going to help you stop faster as it is ultimately the tire that dictates how much braking force you can apply to the rotor before the tire locks.

How does the car handle under braking when you don't lock the front tires? That, combined with brake temps is what you should be using to determine if you need to change pad compounds. I find that the HP+ works very well in the rear with Direzza Z1 tires, not r-comps, but really close.

[e36 323ti]

Originally Posted by Cali330ti

I'm running M3 front setup w/ some surprisingly good bite brembo sport pads. Stock rear ti w/ Hawk HP+. Through me doing an S50 swap I've lost ABS. No ABS light but I don't care anymore....who needs silly ABS in a track car anyhow? Problem is that once the brembo's warm up I get full front lock way before the rears. I'm hoping I can combat this w/ some different pads. Thoughts? Suggestions?

Have you done the bias calculations? M3 front setup (315mm disk and 60mm piston) and stock ti rear (272mm disk and 34mm piston) gives the static bias of 78.3%. In my opinion this is way to much front bias. With a rear caliper with piston dia. of 40mm your bias would have become 72.3%, which is pretty close to the stock bias of 72.6%. In my calculations I assume same pad material front and rear.

With a rear caliper with piston dia. of 38mm your bias would have become 74.3%.

I am currently using AP-Racing 4-pot caliper and 330mm front disk and stock 272mm rear with caliper from late e36 328i (piston dia 38mm). This gives a perfect bias (i.e. stock bias) with my setup, and I can use the same padmaterial front and rear. I have tried a bias setup close to your 78% with Ferodo DS2.11 front and Ferodo DS2500 rear. That was really bad. It felt like the rear brakes had nothing to do.

Now I am using Performance Friction 01 (PFC 01) for track (front and rear), and the bias is perfect. With R-compound the stopping power is awesome. So far, there are no signs to uneven pad deposit on the disks, which I experienced was a problem with the Ferodos.

Note: The rear caliper that I am curretly using is for 19mm disks, and because of this, some spacer have to be used on the outer pad in order to be sure that the piston don't pop out because of pad wear. However, I am going to see if the rear caliper from e34 m5 3.6, which has 38mm piston on 10mm solid disk wil fit.

[Cali330ti]

Thank you. I really think this is closer to my issue. Freshly rebuilt front calipers, solid guides, and stainless lines w/ some high bite auto-x style pads vs. old teeny rotors stock calipers and lines w/ those HP+ pads...the pads would do well if there was more of a braking % done by them. I'd also like to use the same pad all around.

I have a line on some of the Massive rear setup and may pick them up. Getting dia. of the rotors and pistons. Otherwise....your thoughts on using the 328i calipers and details? What's needed to make those work? If I came across a pair...I'd consider them.

[mohaughn]

You would have to go back to E36 non-M3 hubs/spindles on the front to run 328 brakes..

Note that his calculations are for running the same brake pads front and rear. I would guess that the Hp+ pads have a higher cF than the brembo sport pads. Which would put the brake bias a little bit closer to stock. The nice thing about using the HP+ in the rear is that they work at lower temps. I don't see very high temps on my rear brakes at all.

[e36 323ti]

Originally Posted by Cali330ti

Thank you. I really think this is closer to my issue. Freshly rebuilt front calipers, solid guides, and stainless lines w/ some high bite auto-x style pads vs. old teeny rotors stock calipers and lines w/ those HP+ pads...the pads would do well if there was more of a braking % done by them. I'd also like to use the same pad all around.

I have a line on some of the Massive rear setup and may pick them up. Getting dia. of the rotors and pistons. Otherwise....your thoughts on using the 328i calipers and details? What's needed to make those work? If I came across a pair...I'd consider them.

I would also like to have the Massive rear setup, but I need another caliper to maintain bias (virtual piston dia 38mm) when using them with my AP-Racing up front. I think that doing the bias calculation is a good idea to get a picture of how they would affect the bias. The use of a bias valve is not legal in my country.

Regarding the 328i rear caliper, it bolts straight on the stock ti carrier (you have to use the ti carrier). I had Goodridge steel braided hoses, and in order to reuse them, I had to put the left caliper on the right side and the right caliper on the left side. This means that the 328i calipers then are mounted upside down. I used this setup for more than a year, and it worked very well. One downside was when the brakes had to be bleeded, because the calipers had to be losened in order to let the bleed valve point upwards.

To mount the calipers on the side where they belong, i.e. the right 328i caliper on the right side and the left 328i caliper on the left side, you have to get some custom made steel braided hoses with a straight banjo bolt for the connection to the calipers. The origin of the problem with the stock and similar brake lines when using the 328i rear caliper on the ti, is clearance issues. My custom made steel braided hoses were maid by Earls (http://www.earls.co.uk/).

As previously mentioned, a spacer on the outer pad is needed, since the 328i rear caliper is constructed for 19mm disks and the stock ti disk is 10mm. I simply use an old brake pad (Ferodo DS2500) with removed pad material as "spacer" (which makes my spacer 5.5mm thick). On my track pads, I have made threads in the hole which are on the rear side of the outer pad, and by the use of a small bolt, the spacer is attached to the pad. An issue with the use of a spacer is that there should be no clearance between the pad and the spacer, since clearance would result in increased pedal travel. That's why I would like to test the caliper from the e34 m5 3.6 (up til 10/89), which is made for 10mm solid disks, to see if it makes any differences. If every thing goes as planned, I will know by the comming weekend if they fit.

My philosophy is to find the right brake bias by using proper hardware and using the same pad front and rear. By using the same pad front and rear, the coefficient of friction can be neglected in the bias calculations (at least in theory). Also, the coefficient of friction seems to be a very varying number where the producer gives one number and tests shows other numbers (see e.g. test published on the AP-Racing site and compare the numbers with the numbers given by the producers). To make it even more difficult for those who like to do the math, some producers do not publish the coefficient of friction (e.g. PFC). Further, by using the same pad material front and rear, the search for the perfect track pad has become easier, since one then do not need to take the bias into account. At least, that is my philosophy at my current level of knowledge and experience...

PS: Please have my bad english excused.

[e36 323ti]

Originally Posted by e36 323ti

... I would like to test the caliper from the e34 m5 3.6 (up til 10/89), which is made for 10mm solid disks, to see if it makes any differences. If every thing goes as planned, I will know by the comming weekend if they fit.

Then the fitment test is done. The rear brake caliper from the e34 m5 3.6 (up til 10/89), which is made for 10mm solid disks and which has 38mm piston diameter, bolts stright onto the ti carrier. Perfect fit! Even the old brake lines can be re-used. No clearance issues, and no need for pad spacers.

[andy]

I have to say - upgrading the bushing material in the e36 brakes seems to make a huge difference to me. I had a lot of brake pad problems mostly related to the full surface of the pad not being used.

[e36 323ti]

Originally Posted by andy

I have to say - upgrading the bushing material in the e36 brakes seems to make a huge difference to me. I had a lot of brake pad problems mostly related to the full surface of the pad not being used.

I am using the 'Caliper Upgrade Bushing Kit' from TMS for the rear brakes, but it did not make a huge difference in my setup.

[Cali330ti]

Originally Posted by andy

I have to say - upgrading the bushing material in the e36 brakes seems to make a huge difference to me. I had a lot of brake pad problems mostly related to the full surface of the pad not being used.

Yeah...the fronts are freshly rebuilt using the solid guides and such. Very nice even pad wear.