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Discussion Starter #1
I am switching to single piston(from '71 Grand Prix) manual discs from manual drums ASAP on my '66. Since I am really having a hard time stopping 4100lbs from 120+mph, I would like to have the smallest bore/highest pressure output master cylinder available. There are only a couple of parts countermen around here that can actually look up and find the best parts for me; but, if they aren't there, then the others don't have a clue. So, if someone already has a part # fo a 7/8" or 15/16" bore disc/drum master handy, it would sure save me some grief! I already have prepared the spindles,an adj. prop valve in the rear line, a combo valve for the disc installation, new calipers,pads,rotors,bearings,seals...so all I need is to bend new lines and install.Once installed I can figure out what length front brake hoses I'll need (braided).Can anyone help me out.And if anyone knows off-hand, the Moog# for '66 BBC front springs,and the correct Moroso# for the long wheel studs (heck, while I've got your attention, why not ask for it all?).I want to order it all this week, so i can put it together this weekend.I've searched many posts, but am still unsure of the best parts.Thanks!
 

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Well, I can maybe help out a little... as for the disk/drum MC, I'd suggest you use the manual MC from a 77 Malibu w 6 cylinder, manual brakes. That MC is part number 1639 I believe and has a 15/16" bore, deep pushrod hole, and even comes with a pushrod! The only kinda wierd thing is that the ports are reversed meaning the front line goes to the rear port and such. Not sure why they did that but it works great! I have not been able to find a suitable 7/8" bore mc...

Get some good pads also!

The springs have been discussed many times, but it really depends on what you want. Do a search and see if you can find the links to web pages that have the Moog charts on them... I know they are out there!

Can't help with the wheel studs, I just ordered 1/2" x 3" ones when I did my rearend last year. I ended up having to cut off about 1" each to get my Rally caps back on! Good news is that those wheel studs cut real easy with a cut-off wheel!!

Best of luck,
Bill C.
 

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Discussion Starter #3
BC-I've been to two parts houses looking for a 7/8" bore m/c...to no avail.Even when the book says "manual",two m/c's I ordered came with shallow pushrod holes and the fluid reservoirs were so steeply angled that they wouln't have worked fo me anyhow (obviously needed to be booster mounted). May have located the m/c you suggested; will get it tomorrow and see. In the meantime, I searched for my stashed '71 Grand Prix combo valve and found that it had somehow been put in my outdoor "parts bin", and has been in the mud and leaves for the last six months.After I clean it up,lube it, and make sure it doesn't leak (or is frozen solid),is there any way to determine if it will function properly before installation?? And as for springs, I see that I can get them cheaply and locally, but can't decide whether to get taller, thinner coils or really stout ones.For a strip use only car, would the consensus be with the weaker coils for weight transfer?
 

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working,
you might want to look for another combo valve, rather than trying to get that one cleaned up and I don't know of a way to really test them. I'd just go to the junk yard and find a couple that look the same and are from cars with similiar weight distribution. I've used mid-sized A-body cars and F-body cars interchangably.

I've never tried it, but I think you're on the right track getting a lighter spring for the weight transfer part of it, just be careful as those springs get pretty squirrelly on the road trying to corner and such.

Good luck with the MC.

Bill C.
 

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Discussion Starter #5
BC-got the m/c; it was as you had described...complete with pushrod etc.And,I took apart the old combo valve and fouund it to be corrode beyond my abilities to repair.I compared the valve with a defeective one I had replaced on my'86 S-10, and all the ports and threads look interchangeable.So I guess GM combo valves thru the mid '80's would all be the same(prior to ABS?).Junkyard time.
 

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Glad to hear you got it ok... and If you haven't realized it yet, you can just give the pushrod a good tug and yank it right out! I ended up just using stock clevis/pin pushrod on mine... Also, did you notice that the fluid reserviors are reversed on that MC??!! What I mean is that the front bowl feeds the rear brakes and the rear bowl feeds the front brakes!

I think externally, most of the prop valves were the same, but I'm not sure about internally. I've heard, but never bothered to find out if it's true or not, that the internals might be slightly different. It has to do with the braking bias and limiting the pressure to the rear brakes for cars that are lighter in the rears. Again, I'd just look for something that has similiar size and weight distribution as the '66. Might even look into the big cars like B-bodies (Caprices, Caddies, Impalas, etc) as they had lots of rear end weight also and I'd guess that the front to rear weight distribution is similiar to the Chevelles.

Good luck,
Bill C.
 
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