Rear Brake Conversion - RX7?

From the tranny down to wheel bearings.
User avatar
ten2doyle102
I <3 E30's
Posts: 5462
Joined: Fri Feb 27, 2009 5:17 pm
Location: Appleton, WI
Contact:

Rear Brake Conversion - RX7?

Postby ten2doyle102 » Tue Jun 12, 2012 12:29 pm

I was dinking around a bit with these yesterday and thought to myself, would it be a useful modification to do in the rear of the car? We all know that this has been accomplished many times in front of the car so what would happen if you put it on the rears?


There would be a couple of hurdles to get past.

1) Finding a rotor that would work. Currently, a 1990 VW Corrado g60 rotor is used in the front and is 280mm in diameter. I was thinking that this may work in the rear as well, but the hat depth is much greater. However, I was thinking that this may not really be an issue (well for me atleast) a long as you don't mind losing your parking brake. Mine is not operational so it wouldn't affect me. The only other thing that concerns me a bit is that the back side of the rotor and hub will be a bit more exposed. The hat depth difference from the stock e30 to a g60 Corrado was about 7/8". Do you all think that would/should be a concern? There are other designs out there for the rotors that you could look at. IE sells a 280mm rear brake kit so maybe if you wanted to you could look into replacement rotors from them. I am trying to do this on the cheap since IE would likely charge much more than my whole kit would cost to make.

2) Making a mounting bracket. This really isnt going to be that bad. I just need to figure out a good location and fab something at work.

3) Braking bias issues. I don't really know what this would do the cars braking characteristics. I know alot of people spoke of the bias issues you get when doing the RX7 kit in the front, so would this make things worse? I would venture to say that it would not, but I don't know.

I don't know. This was something I was thinking about trying to do for a cheap way to do the BBK in the rear of the car.


What do you guys think?
Image
User avatar
Yoshi
Site Admin
Posts: 9091
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Rear Brake Conversion - RX7?

Postby Yoshi » Tue Jun 12, 2012 12:48 pm

I thought RX7 rears were single piston?
Image
Status: HG repair. 488wtq though!
User avatar
M20_fever
Größter Vorsitzender
Posts: 11026
Joined: Fri Feb 27, 2009 1:28 pm
AntiSpam: No
Location: Northern IL

Re: Rear Brake Conversion - RX7?

Postby M20_fever » Tue Jun 12, 2012 12:57 pm

One problem with the difference in hat thickness will be wheel fitment since the caliper will be almost an inch farther outboard.

What does the rx7 rear rotor look like? Or front rotor for that matter?

Have you considered using the stock rotor with a better caliper?

If you do go to a larger rotor and caliper will the stock master still work?

I am at a point where I don't mind losing the parking brake, but if you want to produce this kit most people with street cars will probably want to keep it. Maybe look at some Mini rotors?

Yoshi, he's talking about using the same rx caliper as the front.
Image
Midwestern Councel C Prepared class champion 2012
North Suburban Sports Car Club C Prepared class champion 2012
HSAX Instructor

GET YOUR E3P GEAR HERE: http://www.cafepress.com/e3pgearshop
User avatar
Yoshi
Site Admin
Posts: 9091
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Rear Brake Conversion - RX7?

Postby Yoshi » Tue Jun 12, 2012 1:01 pm

oh... yea that would destroy brake bias unless you played with pressure settings.

Why not retrofit later model bmw ones?
Image
Status: HG repair. 488wtq though!
User avatar
M20_fever
Größter Vorsitzender
Posts: 11026
Joined: Fri Feb 27, 2009 1:28 pm
AntiSpam: No
Location: Northern IL

Re: Rear Brake Conversion - RX7?

Postby M20_fever » Tue Jun 12, 2012 1:08 pm

Rotors? Because their 5 lug. Maybe look at the Corrado rear rotor?
Image
Midwestern Councel C Prepared class champion 2012
North Suburban Sports Car Club C Prepared class champion 2012
HSAX Instructor

GET YOUR E3P GEAR HERE: http://www.cafepress.com/e3pgearshop
User avatar
ten2doyle102
I <3 E30's
Posts: 5462
Joined: Fri Feb 27, 2009 5:17 pm
Location: Appleton, WI
Contact:

Re: Rear Brake Conversion - RX7?

Postby ten2doyle102 » Tue Jun 12, 2012 1:11 pm

Later ones as in?

As for brake bias, people seem to complain that e30 are too front biased, so wouldn't going to a setup like this even things out? Or do you figure these will overpower the rear tires causing them to lock up severely?

Tony, the concerns of pushing the caliper out even further I don't see as an issue. I figure that if you've got them to clear the wheels up front, they "should" clear in the back.

I've been doing alot of research and it seems like anything I find out there is the same diameter so there's no difference. The Corrado Rears are TINY. Like 220mm
Image
User avatar
Yoshi
Site Admin
Posts: 9091
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Rear Brake Conversion - RX7?

Postby Yoshi » Tue Jun 12, 2012 1:35 pm

I meant just getting like E46 rear calipers. You shouldn't need new rotors right? Just place the caliper farther out if the E46 one is bigger. *shrugs* I'm no good with braking systems. I know enough to replace parts.
Image
Status: HG repair. 488wtq though!
User avatar
ten2doyle102
I <3 E30's
Posts: 5462
Joined: Fri Feb 27, 2009 5:17 pm
Location: Appleton, WI
Contact:

Re: Rear Brake Conversion - RX7?

Postby ten2doyle102 » Tue Jun 12, 2012 1:37 pm

You could perhaps mount a caliper further out like that, but you'd only be contacting a smaller portion of the rotor.
Image
User avatar
Yoshi
Site Admin
Posts: 9091
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Rear Brake Conversion - RX7?

Postby Yoshi » Tue Jun 12, 2012 1:44 pm

I thought you'd be contacting more since there is more surface area? Confused.
Image
Status: HG repair. 488wtq though!
User avatar
M20_fever
Größter Vorsitzender
Posts: 11026
Joined: Fri Feb 27, 2009 1:28 pm
AntiSpam: No
Location: Northern IL

Re: Rear Brake Conversion - RX7?

Postby M20_fever » Tue Jun 12, 2012 2:02 pm

Calipers made for larger rotors have a deeper engagement for the pistons.

I'll do a little digging on rotor selections as well Matt.
Image
Midwestern Councel C Prepared class champion 2012
North Suburban Sports Car Club C Prepared class champion 2012
HSAX Instructor

GET YOUR E3P GEAR HERE: http://www.cafepress.com/e3pgearshop
User avatar
ten2doyle102
I <3 E30's
Posts: 5462
Joined: Fri Feb 27, 2009 5:17 pm
Location: Appleton, WI
Contact:

Re: Rear Brake Conversion - RX7?

Postby ten2doyle102 » Tue Jun 12, 2012 2:08 pm

The rotor itself isn't big enough for the entire brake pad to contact it. The stock e30 rear rotor surface area is much smaller and is barely enough for the stock brake pad to fit properly. Going to a bigger caliper and pad will only mean that the pad will likely hang off the rotor. I need a larger diameter rotor in order to take advantage of a bigger rear caliper and pad setup.
Image
User avatar
ten2doyle102
I <3 E30's
Posts: 5462
Joined: Fri Feb 27, 2009 5:17 pm
Location: Appleton, WI
Contact:

Re: Rear Brake Conversion - RX7?

Postby ten2doyle102 » Tue Jun 12, 2012 2:14 pm

Another thought I had would be redrilling a set of rotors from a e36 or e46 to fit a 4x100. Those rotors are massive on those cars...
Image
User avatar
M20_fever
Größter Vorsitzender
Posts: 11026
Joined: Fri Feb 27, 2009 1:28 pm
AntiSpam: No
Location: Northern IL

Re: Rear Brake Conversion - RX7?

Postby M20_fever » Tue Jun 12, 2012 2:18 pm

Redrilling could kill the "budget" part of this though.

found on a Honda forum:

There is no difference between "GSR" brakes and RS/LS/SE/GS Integra brake components. They all use the same calipers, pads, and rotors. The only Integra with different brakes is the ITR.

'92-95 Civics with ABS and '92-95/'99-00 Civic Si have those same rear disc brakes, as do the del Sol Si and del Sol VTEC.

And FWIW, the '90-91 CRX Si rear brakes are the same as the Integra rear brakes. The '90-93 Nissin 7CLP13S rear caliper body is just slightly different than the '94+ 7CLP13S-R3 body, but functionally the same.


he is talking about a 262mm rear disc. Not sire on hub bore or hat offset though.
Image
Midwestern Councel C Prepared class champion 2012
North Suburban Sports Car Club C Prepared class champion 2012
HSAX Instructor

GET YOUR E3P GEAR HERE: http://www.cafepress.com/e3pgearshop
User avatar
ten2doyle102
I <3 E30's
Posts: 5462
Joined: Fri Feb 27, 2009 5:17 pm
Location: Appleton, WI
Contact:

Re: Rear Brake Conversion - RX7?

Postby ten2doyle102 » Tue Jun 12, 2012 2:38 pm

The rear disk on an e30 is 257 so that's not much of a gain.

I don't think that redrilling the rotor would be that hard to do. If anything, I can provide a cheap template to do it and then people and just to themselves.

The e36 328i rear disk is a 5x120 bolt pattern and it looks like it would almost work to redrill it to 4x100.

I am not sure on the bore differences though.
Image
User avatar
M20_fever
Größter Vorsitzender
Posts: 11026
Joined: Fri Feb 27, 2009 1:28 pm
AntiSpam: No
Location: Northern IL

Re: Rear Brake Conversion - RX7?

Postby M20_fever » Tue Jun 12, 2012 2:54 pm

I dunno, if your going to redrill a 5x120 to 4x100 you going to get the same problem as people drilling wheels. One of the holes will overlap the other. You would need to fill/drill the rotor, or get blanks from somewhere. Both of those options are pricey. Even with a template, drilling the rotors is not something that should be done in a garage IMO.
Image
Midwestern Councel C Prepared class champion 2012
North Suburban Sports Car Club C Prepared class champion 2012
HSAX Instructor

GET YOUR E3P GEAR HERE: http://www.cafepress.com/e3pgearshop

Return to “Drive Line”

Who is online

Users browsing this forum: No registered users and 2 guests