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  #1  
Old 09-13-2002, 02:35 AM
Mach Manny Mach Manny is offline
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Default 8 3/4 swap, brake woes

Ok well the 8 3/4 is in, did the u-joint conversion, tightened the u-bolts, .... but i have no rear brakes! The car right now is on stands with the rear wheels in the air, and when i put it in gear the brakes are overpowered at idle! So apparenlty i have LITTLE braking power. I already bled the brakes.. and what i think i have is mechanical...

I pulled the drums to see if they were even getting shoe wear, and i noticed a few things. Right next to the surface where the shoes contact the drum, on the perpendicular plane, there is contact between the drum and the shoe's metal backing plate. It seems like the drums are about 1/4" too deep, or the shoes are 1/4" too wide, and the shoes rub the inside 'corner' of the drum. Because of this, it seems like i cant expand the shoes out to contact the drum correctly. (pics soon if this is hard to imagine)

All the parts were pulled from 3 seperate vehicles, but i figured all 8 3/4 parts are compatible. But another thing i noticed, was that the retaining pins required (that look like hammerhead tiped tails) were about 1/4" longer than then ones from my drum brake donor.

Do i have incorrect shoes/drums?
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  #2  
Old 09-13-2002, 06:24 AM
Duffys Ramcharger Duffys Ramcharger is offline
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I've never heard of this problem, but I'll give it a try. Are the drums and back plates from the same vehicle? I would think that the back plates aren't mounted back far enough. Or if you're talking about the edges of the shoes hitting the drums, are they the right shoe size? Use a tape measure to check the depth of the drums and the width of the shoes. With out seeing it, I'm just gestamating Maybe some else had this problem before.
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Old 09-13-2002, 02:11 PM
72Challenger 72Challenger is offline
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There are different width drum brakes. Sounds like you're mismatched. Does the drum seat all the way against the axle? Do the shoes seat against the small raised "nubs" on the backing plates? (Sorry, I hope you know what I mean, again this is something hard to describe without a picture. But there are 4 or 6, can't remember, places where the backing plate has raised, flat surfaces for the inward edge of the shoe to rest against.)

If I recall correctly, the width differences of the brakes were in 1/2" increments, so if they are mismatched, I doubt you could get both the shoes and the drums to seat properly. But based on the length differences in the retaining pins, it does sound like a parts mismatch.
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Old 09-13-2002, 04:58 PM
Mach Manny Mach Manny is offline
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Quote:
Originally posted by 72Challenger
Does the drum seat all the way against the axle? Do the shoes seat against the small raised "nubs" on the backing plates?
Yes, the shoes appear to seat correctly on the backing plate, against the raised 'nubs' of the bplate. The drum also seats against the axle shaft, but it's pressed up against the side of the brake shoe.

I'm not sure what the housing, axle, or 3rd member came out of, but the backing plates are off a 71 Imperial, which is what i got the shoes speced for, and the 11" drums came off an 8 3/4'ed van.

Maybe i should get the backing plates off the van to match the drums, which may have the deeper dish and hence shorter retaining pins?

If all else fails, swap the 10" brakes from the 8 1/4 back on?
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Old 09-13-2002, 07:34 PM
72Challenger 72Challenger is offline
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I think you should try the other backing plates first. If both the shoes and the drums are seating, then I am sure that they are the right size for each other. The small amount that you are off by would certainly seem to be from the plate moving the shoes out too far. Seems like the safest bet is to match parts whenever possible, so yes, try to get the backing plates from the van.
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Old 09-14-2002, 12:25 AM
Mach Manny Mach Manny is offline
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Ok, well i decided to run the 10" drums off the 8 1/4 instead, and go with a disc brake conversion in the future. I got the passanger side all done today and everything checked out...

but now on the driver's side, i cant get the axle shaft out!?!?!? I dont think it makes a difference, but i had switched the L/R shafts and used the one with the endplay adjuster on the driver's side. I last put the brakes together and drove around for about 20 miles to troubleshoot the brakes... and now the shaft wont come out! What gives? I dont want to pry on the flange, and i cant borrow a slide hammer until tomorrow.. any suggestions?

Thanks.
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  #7  
Old 09-14-2002, 01:01 AM
Mach Manny Mach Manny is offline
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Ok here are some pictures:

pic #1, this is where the drum appears to be bottoming out and contacting the drum. The arrow points to the metallic backing plate of the shoe that is rubbing the inside of the drum.
Attached Images
File Type: jpg photo5.jpg (51.9 KB, 11 views)
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Old 09-14-2002, 01:02 AM
Mach Manny Mach Manny is offline
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pic2, this is the inside 'corner' of the drum that is contacting the brake shoe's metallic backing plate. It's metal-metal contact...
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File Type: jpg photo2.jpg (44.0 KB, 9 views)
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  #9  
Old 09-14-2002, 01:07 AM
Mach Manny Mach Manny is offline
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pic3, here is how the drum seats on the shaft flange. The white ring is the contact area of the drum and wheel.
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File Type: jpg photo11.jpg (51.3 KB, 7 views)
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  #10  
Old 09-14-2002, 01:13 AM
Mach Manny Mach Manny is offline
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pic4, here is how the drum levels with the backing plate.

thanks for the help.
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  #11  
Old 09-14-2002, 01:15 AM
Mach Manny Mach Manny is offline
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pic5, this shaft WON'T come out!?!??!
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  #12  
Old 09-14-2002, 01:46 AM
Duffys Ramcharger Duffys Ramcharger is offline
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A little trick that I use to get the axle out, get a piece of chain about 10 feet long. Put the end link on one of the studs and put a lug on. Grab the other end of the chain and "whip" it like you were trying to pull it toward you. This is what I use as a puller.
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