Rear Brake Conversion - RX7?

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Re: Rear Brake Conversion - RX7?

Postby ten2doyle102 » Tue Jun 12, 2012 2:58 pm

Well, either way, I figure this is gonna be a heck of alot cheaper than purchasing a full rear brake kit. IE's kit is like $1000 for a 280mm setup.

I figure that you could get this done for half that, maybe less if you are resourceful.
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Re: Rear Brake Conversion - RX7?

Postby ten2doyle102 » Tue Jun 12, 2012 2:58 pm

or if you have friends that can machine stuff for you.
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Re: Rear Brake Conversion - RX7?

Postby ten2doyle102 » Tue Jun 12, 2012 3:04 pm

Here is the overlap between the 5x120 and 4x100. One hole really. Do you really need to fill them all? I am asking could I don't see why you couldn't just drill the other 3 and slot the 4th one as such.
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Re: Rear Brake Conversion - RX7?

Postby M20_fever » Tue Jun 12, 2012 3:59 pm

Guess its ok:

http://www.sfldrifters.com/forums/showthread.php?t=2543

If we're talking about doing this for a 280mm rear kit, why not a 300-320mm front kit?? I think having the same size front and rear will cause biased issues, you want bigger up front.
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Re: Rear Brake Conversion - RX7?

Postby ten2doyle102 » Tue Jun 12, 2012 4:34 pm

Maybe that's way there's already a bias issue on the e30's then? The stock setup is supposedly 260mm in front and 257mm in the rear. This info is from the Bendix web site. It give you dimensions! :)

Rear e30

http://www.bendixcatalog.com/PartDetail ... ke%20Rotor

Front e30

http://www.bendixcatalog.com/PartDetail ... ke%20Rotor

Although Tony, I think you're figuring that the bias would be more towards the rear??? If this is the case, I would assume that making the rear bigger would help to balance it out again.
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Re: Rear Brake Conversion - RX7?

Postby M20_fever » Tue Jun 12, 2012 4:51 pm

Based on that I guess it would be closer to stock bias then having larger brakes up front like I do now. I figured it would give a neutral bias. I still want 300mm fronts and 280mm rear. :)
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Re: Rear Brake Conversion - RX7?

Postby Nsquared97 » Tue Jun 12, 2012 5:11 pm

Here's my $.02.

If I was interested in this, I would most likely want the parking brake to still work, but at this point unless I am seriously tracking my car at say Road America, I don't have a whole lot of interest.

As far as the bias issues, the current problem is that when you go with a BBK up front, you are seriously shifting the brake bias to the front of the car (moreso than stock). So doing a BBK for the rear should definitely help with evening the bias back out. Keep in mind you always want to have more front brake bias than rear due to weight shifting forward when the brakes are applied.

As far as the stock system goes, just keep in mind it isn't just rotor size that determines bias. Rotor size, caliper selection, pad size/material all plays a big role in the actual clamping force you are getting on each wheel.

Just out of curiousity, are you guys running the stock ABS system or no?
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Re: Rear Brake Conversion - RX7?

Postby ten2doyle102 » Tue Jun 12, 2012 5:40 pm

Yes, I would be running the stock ABS system in it as well.

I know there are probably other thing out there that would probably work and maintain the parking brake, however I never use it any way so I personally don't mind not having it installed.

I tried getting a rotor today.... with no luck. :(
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Re: Rear Brake Conversion - RX7?

Postby M20_fever » Tue Jun 12, 2012 5:48 pm

Yeah I still use abs. The car is definitely a little heavy on front bias with the rx kit ans stock rears. A bbk in the rear would probably help a lit in getting back to stock bias. My question is, will the stock booster still work with the bbk front and rear? I should see if Lee will chime in in this discussion as he is an expert at this kind of stuff.
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Re: Rear Brake Conversion - RX7?

Postby ten2doyle102 » Tue Jun 12, 2012 5:57 pm

That'd be cool!
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Re: Rear Brake Conversion - RX7?

Postby Nsquared97 » Tue Jun 12, 2012 6:24 pm

Yeah I was thinking the same, Lee definitely would have some good input on this.
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Re: Rear Brake Conversion - RX7?

Postby Lee » Tue Jun 12, 2012 6:36 pm

Rear BMW Z1 (late serie) is 4 bolts, 280x10mm and a direct bolt-on. A mix of e30/M3 carrier/calipers will make it a bolt on.
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Re: Rear Brake Conversion - RX7?

Postby M20_fever » Tue Jun 12, 2012 6:45 pm

RealOEM is showing the rotors at $125 each. For that money you can get a "real" rear bbk...on a unrelated side note, it shows the front rotors are only 260mm? So the rear is 280 and the front is 260? I thought the front was always supposed to be bigger?
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Re: Rear Brake Conversion - RX7?

Postby Lee » Tue Jun 12, 2012 7:01 pm

Early and late Z1s don't have the same brake components. Later = bigger.
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Re: Rear Brake Conversion - RX7?

Postby ten2doyle102 » Tue Jun 12, 2012 7:13 pm

I was reading up on those Z1 rotors. They are quite hard to come by it looks like....
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