Big brake caliper help..... Bill Verburg

[84toy]

I am in the middle of a brake conversion and I just now discovered that my rear calipers are not what I had thought. I am using 964 RS fronts 44\36

It now it appears the rears I want to use are 944T\964 fronts. The piston sizes are 40/36 and the pad LxW is 98x44.

I do have a PV for the rear but I am worried that these calipers are too big. Clearly, the fronts have much more pad area, pistons and larger rotors but I'm still worried......The hydraulic ratio comes out at about 1.135

Thoughts?

[Bill Verburg]

Moving fronts to rear is usually a disaster

A p/v is a fine tuning aid it can only help match desired bias curves a little.

You want 993 4 piston rear calipers 30/34, on either stock rotors or if you want drilled 968 M030 rear rotors. Most prefer no p/v w/ this setup

If you are willing to give up the parking brake an even better choice is 322x28mm Alcon rotor w/ a hat and 993RS 30/36 rear calipers, a p/v is definitely needed here

Did you get true 964RS front(same as 964t 3.3 front)? or are you using 993 front equivalents

[84toy]

Wow, that was fast...thanks Bill.

Here is the problem....Fronts are finished (964RS) and the rears (with rotors) were literally on the car. I needed the anti squeal disks and that is when I noticed the piston size. Poor mistake on my part.

The big question is can I run this with success on the street using the adjustable PV? Too late to re-buy everything.

Here is the setup. Second pic is the rear caliper

[Bill Verburg]

I wouldn't, it's your neck

[84toy]

Originally posted by Bill Verburg

Did you get true 964RS front(same as 964t 3.3 front)? or are you using 993 front equivalents

Thanks for the help Bill.

Yes, the fronts are the true 964RS. Actually you helped me and Dave Walsh figure that out a few months ago.

Are the 993 4 piston rear calipers 30/34 calipers you are suggesting the same exact dimensions as mine except for smaller pistons?

My setup is very custom and a lot of fabrication has been done to get where I am. I'll be in a world of hurt if the smaller pistons version is not the same dimensionally. Look at the picture. It will need to bolt up the same.

[Bill Verburg]

Originally posted by 84toy
Thanks for the help Bill.

Yes, the fronts are the true 964RS. Actually you helped me and Dave Walsh figure that out a few months ago.

Are the 993 4 piston rear calipers 30/34 calipers you are suggesting the same exact dimensions as mine except for smaller pistons?

My setup is very custom and a lot of fabrication has been done to get where I am. I'll be in a world of hurt if the smaller pistons version is not the same dimensionally. Look at the picture. It will need to bolt up the same.

Ok, Now I remember

Yes, the 993 rear bolts up exactly the same as the 964, all of the small 4 piston Brembos have the same mounts.

What rotors are you planning on using in the back? If its a 24mm Carrera rotor you are all set w/ the 993 rear. If it's the 28mm 930 rotor then a 965 rear is perfect (but rare) and the 993 will need to have it's throat clearanced(easily done by hand)

[84toy]

Yep, I'm using the Carrera rotors so it's an easy fix.

The entire brake upgrade is a major overkill for this car. I was not going to do this but the Daughter Project needed everything in the brake dept (stored over 12 years). I stumbled on a good deal on the calipers so I yanked all my freshly rebuilt Carrera brakes off the 3.6 project and bolted them direct on her car. Now I'm proceeding with the big upgrade.

It actually cost almost nothing additional to do it weighing the costs of replacing the daughter project brake system.

Now all I need to do is get the right size calipers. If anyone is readiing this and has a set of calipers that Bill is talking about please PM me

Bill......Thanks! I'll post a WTB

[Bill Verburg]

Sounds nice, I do have a complete extra set of 993 calipers powder painted orange/red but that doesn't help you as I won't split them up.