Brake Specs and Questions

[osborni]

Pricing out an Ultima in the US.

Wilwood brakes are much more common (at least in Iowa....) then AP. So I'm looking into the pricing on Wilwood calipers, hats, etc. for the replacement part convenience.

What are the sizes of the caliper pistons, rotors and hats that are speced on the Ultima?

How close to neutral is the balance bar adustment? (Did the factory get it right? - I assume so, but want to ask anyway...)

How is brake performance on the street and on the track (assuming proper fluid and pad selection)?

Thanks!
Ian

[steve_D]

osborni said:

Pricing out an Ultima in the US. Wilwood brakes are much more common (at least in Iowa....) then AP. So I'm looking into the pricing on Wilwood calipers, hats, etc. for the replacement part convenience. What are the sizes of the caliper pistons, rotors and hats that are speced on the Ultima? How close to neutral is the balance bar adustment? (Did the factory get it right? - I assume so, but want to ask anyway...) How is brake performance on the street and on the track (assuming proper fluid and pad selection)? Thanks! Ian

You may have problems establishing the required mounting brackets etc.
Unless someone has an AP kit they have not fitted yet it would be difficult to find the dimensions you require.
The discs are about 330mm and 38mm thick. The callipers have one piston smaller than the other to compensate pad wear but I don't know the sizes.
Brake performance of 100mph to a standstill in 4.4 seconds and in a distance of 83meters has to be more than adequate.

Steve

[osborni]

I have the ability to size and manufacture a caliper mounting bracket. (Mechanical Engineer and I have a table top milling machine)

What I need to know now (Thanks for the rotor specs!) is the size of the pistons in the calipers. Need to make sure the pedal ratios and brake torque are as close as possible.

IMHO - 1 time brake stopping distance is more a function of the tires and brake balance. Your every day Ford/GM/whatever floating caliper car can lock the wheel up at high speeds, but only if the temps stay low. The big rotor and caliper is to manage and dissapate heat on a road course where rotor temps can get over 1000F.

[bigmack]

Ultima's website lists the 4 pot AP calipers with 1.5" and 1.625" pistons and 320mmx30mm discs. I went my own route when sourcing the brakes. I went with Brembos and had Brembo N.A. recommend a caliper/disc combo that would work best with this car based on a number of factors. Equal size front and rear caliper/rotors are best for this car. Most of the calipers now are sold with different size pistons for better wear. Being an engineer, you shouldn't have any trouble with the caliper brackets or hats but I recommend you check out www.colemanracing.com for the hats anyway. They've got a sweet CNC design for them, but they were a little pricey ($200 per hat). Mine are floating discs with curve vaned 328mm rotors instead of cross drilled rotors. The beauty of going with either AP, Wilwood, or Brembo is that everyone makes pads for these calipers. I run a street compound pad for around town and have a race pad for Auto-X and trackdays.
The brakes are unbelievable in this car! The car stops faster than anything I've ever been in. It would throw you into the windshield without your harness fastened. The brake bias is 50/50 in the middle as measured on my SPA bias gauge. I prefer more rear bias with the car to take advantage of the large rear tires 45/55 front/rear to 40/60 front/rear. Others prefer more front bias and just the opposite. Of course on rainy days you want a little more front bias.
Now, having said all of this, people like myself who have sourced their own brakes, are a rare breed! It is highly against the factory's recommendation to source your own brakes, and they have spent a lot of testing coming up with their recommended caliper/disc combo. For someone who is sourcing a complete setup, discs, calipers, hats(bells), and brackets, and is not an engineer, you can expect to pay considerably more for another setup. I know I've dropped over $7k to $8k for my setup when it was all said and done. With a couple of spare hats that were the wrong offset. I'm very pleased with my setup, but it would have been a lot cheaper to go the factory route. Then again, I really didn't have to go with a race caliper either. Ha.
p.s.Get a caliper with dust seals or else you'll need to rebuild them quite a bit. Anti-rattle clips are also nice.
Cheers!
-Mack

[osborni]

Thanks for the info!

Just what I'm looking for.

One last question, what is the wheel stud bolt pattern and hub centric size?

Ian

>> Edited by osborni on Sunday 26th September 00:05

>> Edited by osborni on Sunday 26th September 01:37

[bluesatin]

You shouls find all you need here

www.apracing.com/roadcar/caliper/index.htm

[k wright]

I don't know how often the calipers and rotors need service. Everybody knows the price of them. It takes about 2-4 hours to completely fix them to the chassis and they definately work well.

Unless you are interested in something that you really think is better I would highly recommend the factory set up.

ken

[osborni]

Looks like the factory is using CP5200 calipers.

Since the exchange rate sucks right now, I can find less expensive calipers sourced locally then from the factory. This is the main driver for asking these questions.

Thanks!

[jschwartz]

I was gonna use Wilwoods as well. Ended up using the Factory AP's. I talked to a number of competitors at Run and Gun this week and all said their experience shows that AP to be superior to Wilwood. I was told the main problem with the Wilwoods is caliper flex. The factory AP's have been 17,000 miles and 7 days of track use and I've never even had to bleed em. I saw Cobra replicas with boiled brake fluid and cars jacked up all week. I'm glad I used the AP's. You're building a pretty expensive car, don't cheap out on the brakes.
You may end up spending more in the long run sorting out pad compounds etc. My opinion.
Jeff Schwartz.

[osborni]

jschwartz said:

I was gonna use Wilwoods as well. Ended up using the Factory AP's. I talked to a number of competitors at Run and Gun this week and all said their experience shows that AP to be superior to Wilwood. I was told the main problem with the Wilwoods is caliper flex. The factory AP's have been 17,000 miles and 7 days of track use and I've never even had to bleed em. I saw Cobra replicas with boiled brake fluid and cars jacked up all week. I'm glad I used the AP's. You're building a pretty expensive car, don't cheap out on the brakes. You may end up spending more in the long run sorting out pad compounds etc. My opinion. Jeff Schwartz.

Yah - I keep coming back to the PITA factor of not going with factory brakes. Too much design work to save about $400 in total cost, time and mistakes not included.

[BigAl1]

I too looked at alternatives for price reasons, but will use the factory system as it is well proven, and actually a better total cost than the Brembo setup that Brammo is selling. Go with the factory AP system.

Allan