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Fix it until it breaks
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Discussion Starter · #1 ·
My '37 Plymouth was not built by me and I didn't get a lot of info with the car. What little work I've had to do so far has been straightforward, but now it's getting a little difficult because I'm not quite sure what parts I'm dealing with.

The front suspension appears to be an original (not an aftermarket kit) Mustang II crossmember and arms. I suspect an aftermarket rotor and disc brake "system" but don't know the supplier. I looked for part numbers and I did annoy the counter guy at NAPA for a while to try to discover things. Here's all I found/know:

The brake master cylinder is a '74-vintage Corvette (NAPA 39052), the front brake calipers are from an '84 Camaro (NAPA 442-2032M, 422-2033M). The rears brakes are also Camaro calipers with an integral parking brake attached to a NOVA II diff. The power brake booster has no visible part numbers or markings and is 6-3/4" in diameter at the widest point. The front 10-1/2" ventilated rotors are marked with "81906" on the right and "81905" on the driver's side. The outer wheel bearing is marked "BOWER" "LM12749" "AT" and the inner bearing is marked "BOWER" "L68149" "2L"; the inner seal is marked "National" "471854". The upper ball joint on what may or may not be a stock spindle is marked "8280" and the lower "8373: they are both bolted, not riveted. The caliper mounting bracket is C-shaped and crudely finished (edges rough and sharp). The shock absorber is painted white, has no label, and is marked "20814" "P6283C1P". The coil springs appear to have had a coil (or less) cut off and the lower A-arms angle up slightly from the frame. The suspension bushings appear to be original to the donor car and are dry and cracked where I can see them.

When I was by the Detroit Eaton Springs shop in September, the folks there examined the car and sold me a new set of springs that will bring the geometry back in line for the weight of the vehicle; the ride height and "hot rod rake" will still be good.

The reason I got started on this post was that the brakes always felt marginal; lot's of pedal travel and the pedal never got to the floor, but I never could get the brakes to lock up. I bled the brakes and adjust the pushrod, but no improvement and I'm not certain the vacuum booster even works. After depressing the brakes, the pedal would slowly return to it's full up position (but not while the engine wasn't running - it moved normally then) and the brakes would drag. I should also mention that originally there was a 2lb residual valve near the m/c in the front brake line, but not the rear (m/c mounted under the floor). I added one to the rear brake line with no noticeable change in braking. I also noticed that the fitting/line closest to the m/c mounting flange fed the rear brakes and this is reversed from what I had read for GM master cylinders. True?

So, I plan on replacing the coil springs and the front suspension bushings while I have things apart, but does anybody have an idea of what brake "kit" was used? A source for the power booster if I need one (how do I tell if it works or not?)? What rotors I have? And, most importantly, any idea of why brake performance is crappy? I'd like to fix it all now while it's apart.

Hoyt
 

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Troll Hunter
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2,694 Posts
Almost all brake conversions for MII front ends use the same components. I believe that depending on which pattern you have (GM or Ford), sounds like it is probably GM, I believe they use a Camaro or Volare type rotor. Check any parts book that offers that conversion and you can find out exactly what it is. I think ALL of the rod shop suppliers offer that kit. Heidt's does and you can check out Speedway Motors, and as I said, probably every other one.
 

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Fix it until it breaks
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672 Posts
Discussion Starter · #3 ·
Bolt pattern

Thanks, that gives me a place to start.

It's a 5-lug 4-3/4" pattern. I'm headed back to a different parts store to see if they can cross-reference the bearing numbers and part number of the rotor so I can see what I really do have.

The difficult part to look up is going to be the power brake booster. I can call some of the aftermarket brake kit suppliers who offer similar stuff and see if they will tel me.

If only people would write this stuff down when they build a car. Even _they_ forget after a while; I can't remember after a week unless I write it down . . .

Hoyt
 

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Fix it until it breaks
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672 Posts
Discussion Starter · #5 · (Edited)
The ECI power booster _looks_ like it is the same one and would most likely work with the 67-76 Corvette m/c I use (since they sell the same m/c booster combo), but given he cost of their combo and the cost of the m/c itself, they seem at tad expensive. I do like the remote res. feature of their EC-495 unit; I wonder what m/c that uses? It looks like a later model Corvette part.

UPDATE

Here's a site I found that provides a lot of good info and reasonable deals on parts, and you gotta love the name. http://www.piratejack.net/

I decided to upgrade to a dual diaphragm 7" booster due to he weigh of my car (about 3400 pounds).

The front rotors are indeed Camaro, but don't use the OEM bearings on the Mustang II spindles. I was able to cross-reference the existing bearings, but it would be nice to know he original application for them. The cross-referenced oil seal has the same number, but looks different; the new one has a flange in the same plane as the rotor.

I'm also upgrading to poly suspension bushings while I have everything apart
Thanks to all for the help.

Hoyt
 
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