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Rear disc conversion help

Old 11-19-2018, 03:11 PM
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Rear disc conversion help

I have an 85 that I'm converting to rear disc. Got a rear from an 91 !LE car complete with everything including e brake cables. After much research seems I need a new proportioning valve. I have searched and searched and can't find a part number or a place to get it. I have found on here that some say you just need to replace the spring but again no part numbers or supplier.
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Old 11-20-2018, 05:00 AM
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Re: Rear disc conversion help

Originally Posted by Fullmonte77 View Post
I have found on here that some say you just need to replace the spring but again no part numbers or supplier.
Read this thread for Spring Voodoo - https://www.thirdgen.org/forums/brak...e-upgrade.html

Pretty sure finding a prop valve for that combo will be difficult. First, no PBR rear discs were offered in 85. Second, most of the PBR equipped cars were 91-92, aside from being somewhat uncommon, the style of threads or flare changed around 89/90. The 89 valve might work, but it's not like they're easy to find. Which is why people play brake bias spring Quija hoping they improve the brakes without going all Paul Walker in the process.

Search for threads by JamesC, he's documented most of the common brake upgrades on his 85.

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Old 11-20-2018, 08:18 AM
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Re: Rear disc conversion help

Just so happens i have an 89 parts car. I can always use adapters on the lines to go from SAE to metric. The link you provided gives a part number witch is what I needed.
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Old 11-21-2018, 11:47 PM
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Re: Rear disc conversion help

You can also just splice in an adjustable prop valve like one from Wilwood and just eliminate the spring altogether. That's how I did mine when I did my C4HD front swap and rear drum to PBR disc conversion. That's also how Baer did it when they offered their original Track disc conversion (which is just the C4HD conversion and rear PBR conversion).
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Old 11-23-2018, 09:05 PM
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Re: Rear disc conversion help

Originally Posted by Manic Z View Post
You can also just splice in an adjustable prop valve like one from Wilwood and just eliminate the spring altogether. That's how I did mine when I did my C4HD front swap and rear drum to PBR disc conversion. That's also how Baer did it when they offered their original Track disc conversion (which is just the C4HD conversion and rear PBR conversion).
this is exactly what i plan on doing this winter to my setup. I have C4HD kit up front and a C4 disc conversion in the rear. if you have time, would you mind posting some photos of your setup? I have yet to decide how I will be plumbing my adjustable prop valve, and also which valve setup to use. any more details would be appreciated. thanks
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Old 11-24-2018, 12:19 PM
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Re: Rear disc conversion help

Originally Posted by IROCZman15 View Post
this is exactly what i plan on doing this winter to my setup. I have C4HD kit up front and a C4 disc conversion in the rear. if you have time, would you mind posting some photos of your setup? I have yet to decide how I will be plumbing my adjustable prop valve, and also which valve setup to use. any more details would be appreciated. thanks
I put mine under the hood. My engine bay needs a good cleaning lol:










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Old 11-24-2018, 12:24 PM
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Re: Rear disc conversion help

Here's an old Camaro Performers article you may find useful. They put the adjustable prop valve under the car:

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Old 11-24-2018, 12:25 PM
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Re: Rear disc conversion help

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Old 11-24-2018, 12:26 PM
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Re: Rear disc conversion help

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Old 11-24-2018, 12:27 PM
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Re: Rear disc conversion help

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Old 11-24-2018, 12:27 PM
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Re: Rear disc conversion help

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Old 11-24-2018, 12:28 PM
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Re: Rear disc conversion help

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Old 11-25-2018, 09:49 PM
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Re: Rear disc conversion help

ah, damn I miss Camaro Performers Mag. In fact, I am certain I read that exact article years ago and probably have the issue in my magazine stash in storage..

I Don't mean to hijack the thread, but it seems the OP and I are in a similar situation...

That is a good idea to plumb it under the car in-line. certainly a possibility..
correct me if I am wrong, but I would need to disassemble the distribution block under the MC, take out the spring and valve and just leave it empty? then just cut the rear line, flare it, install the adjustment valve, bleed the whole system (all 4 corners) and test/adjust accordingly?


I like this idea. However, If I am going to be cutting and bleeding anyways, wouldn't it just make sense to get a whole new PV and dist-block?
like:
https://www.jegs.com/i/Wilwood/950/2...caAmE_EALw_wcB

or is this MORE cutting and flaring and adapters it seems.
regardless. I'll be doing one of these this winter. I am a fan of keeping things clean, streamlined, clutter-free, and visually appealing in the engine bay, btu also need MORE rear brake engagement for autocross and aggressive street driving.
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Old 11-25-2018, 10:10 PM
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Re: Rear disc conversion help

This is an interesting thread. I just completed my drum to PBR rear disk conversion on my 89 Formula. I even did the spring swap to the strongest mentioned spring and the brakes can barely stop the rears from turning at idle.
If im reading the article above correctly, you remove the plunger and spring completely then install the adjustable proportion valve in line, so does that mean with no spring you would get more pressure and if thatís the case then wouldnít a softer instead of stronger spring give you more to the rear since no spring gives you the most pressure? Correct me if Iím wrong. Iíve very unhappy with my lack of rear brakes after doing this conversion. Thanks!
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Old 12-09-2018, 06:00 PM
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Re: Rear disc conversion help

anyone able to clarify/explain a bit more on my thoughts in the post above? thanks
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