Using Scarebird conversion brackets, CRX-HF original trailing arms, '97 Acura Integra calipers (non-R), rotors (non-R), ebrake cables, master cylinder. Questions are:
1. Need to change power brake booster from single to dual diaphragm?
2. If I stick with '97 Acura Integra stuff, with that pb booster bolt on to my honda firewall without mods?
3. Can I use any 4040 proportioning valve, say from a SI or another honda that had 4-wheel discs?

 

1. pretty sure they are all single diaphragm. The crx si with discs came with a 1 " larger booster, you can get one with the matching master cylinder off a disc brake 90-91 crx or 92-93 civic si or del sol si.
2. get the integra stuff if you are also swapping the front brakes.
3. the prop valve has to do with the volume of the calipers and the weight of the car, if you have a crx and are recreating the 90-91 crx rotor diameter setup front and rear get a 90-91 crx si prop valve.

 

Thanks for the quick reply. Had not planned on changing the front calipers to match the rear integra calipers and rotors. Is this a bad thing? Do I stand a chance of blowing out the stock front calipers or brake lines if I go with the setup the way it is right now...stock calipers up front and integra calipers in back? Will the integra mc bolt up to the 90-91Si pbb?

 

As for front brakes blowing, I would say change them since you're going faster....I have a 91 EF hatch...changed rear drums with a 92 DA complete rear disk arm set up from donor car. The civic parts that hold the trailing arm in place were mandatory as the DA parts were longer. I haven't changed front yet as I'm still 1.5.. 8-)

 

I have the same setup on the rear, scarebird and all, on my Civic Si. I went with a 15/16 MC and 4040 prop valve.

One difference is that I went with integra calipers up front. I think the 15/16 MC would have worked fine with the original calipers as well, may have ended up with a little less pedal throw.

 

This is where I sit: Ignoring the crx shop manual bleeding instructions, which gave me no brake pedal, I did RR, LR, RF, then LF. Now have pedal when car is not turned on. When car started, right to the floor. The integra pbb works, the one way valve in the booster hose works. I have no apparent leaks. Have kept the 91 crx hf proportioning valve. I just don't know what I'm doing wrong with the brakes. I feel like I've disturbed a system that has remained untouched since '91. I guess my situation mimics my screen name. WTFBruce

 

If you did change the master cylinder, hopefully bench bled it, my manual has the order of LF - RR - RF - LR.. That's the order I followed when I upgraded my brakes and they are solid. Sounds like you have a lot of air in the lines still. Are you using a hose off the bleeder nipple into a jar of fluid when bleeding to help prevent air getting sucked back in.?

 

I followed the instructions from the mc manufacturer and bench bled it. When bleeding each wheel, the hose was submersed with brake fluid in a jar. I may have made a mistake in letting all the fluid run out when disconnecting the wheel cylinders and not immediately hooking up the calipers. Probably have a ton of air still in the lines. I'll take your advice on the order and let you know the results. Thanks.

 

Integra booster?

You need to adjust the pushrod gap between the booster and MC since you're not using spec parts.

​​​​​Just Google brake pushrod adjustment for instructions or look it up in a manual.

 

The story continues. Re-bled the brakes for the 4th time using your suggestion. Great pedal afterward. Started the car and no firm pedal. I have been experimenting with the rod adjustment. Right now, can't remember if its all the way in or out. Will get to it today. I wonder if I have torn anything inside the booster? When first starting out, I didn't hold onto the rod while adjusting the length and the whole thing turned. That's why I'm wondering if I tore something (does the rod traverse the bellows through a hole and I've twisted the bellows previously?) I checked the booster after running the engine for a minute, removing the vacuum hose from it and heard a whoosh of air just as it was removed. Read somewhere if that occurs the booster is ok. No change in the idle when the brake is applied. Will let you know.

 

This how you test your booster.

http://www.norcalcrx.org/tyson/pics/braketest.jpg

 

The mc and pbb did ok in the tests. Had to tighten two fittings leading to the mc (no apparent drips, just a little wet). Checked all wheels & brake lines...no apparent leaks. The check valve test was interesting. The engine pulsated when started with the vacuum hose was disconnected at the pbb. The test said to let it idle. No warning about how the engine would perform. Settled right down by covering the end of the vacuum hose with my thumb. I'm still using the stock proportioning valve. Have a civic 40/40 that I'm put in this week. Just a big pain messing with the brake tubing. I'm just at a loss as to what is the problem. Still have zip for a brake pedal when the car is started. Thanks again for you help. I'll keep you abreast.

 

Still no brake pedal when car running. Great when it's turned off. When pedal pressure applied and then car started, the pedal doesn't drop a shade then return, it just drops. At times I wish I had never done this to my car. It's turning into a money pit. I've done more extensive changes to autos in the past and figured this would be basically a bolt on swap, bleed the brakes and get on with my life. It seems I can't get anything to work right since I started. Am going to replace the pbb which I think is the problem. I bought one of those "H" looking tools to help me with the rod adjustment. Don't think the "universal" tool worked with the pbb in this case as the rod from the pbb has to come out at least 1/2" and there isn't enough adjustment for that. Really frustrated. That and the fact I've got a better part of $300 in the mc and pbb with it not working as it should. Am going to install the 40/40 ppv. Maybe that's the problem.

 

Well, I finally got brake pedal when starting the car. Bench bled the mc (no air bubbles except from the return lines to the mc I made up). I did put a piece of 7/16 rod inside the mc (approx 3mm long) before installing it back on to the pbb. I was afraid it wouldn't work so I didn't try it out for 2 days. Then I started the car and miraculously had great brake pedal with the car running. I never changed the proportioning valve, using the stock on that came with the car. Have been driving it for about a week. Will be replacing the right front cv drive axle as it makes alot of noise when turning. Would like to thank everyone who responded to my thread. There is such a wealth of knowledge on this subject here and appreciate all you help.