Aluminum Drums

[Mikz86TA]

Howdy! Does anyone know a few things about the aluminum drums. First, What diameter is the original S-series rear drums? Are they the same part for a 7.5 and a 8.5 axle? The aluminum GN drums are the same size and direct fit? Are there any other vehicles they could have possibly been on? I know the GN drums are an old F-body mod too. I guess as long as the bolt pattern is the same, like G-body, S-series and Fbodies, the diameter is the only other diff-if there is any. I remember the F-bodies having only one rear drum size. Also, if I were to get ahold of a F-body alum rear disc calipers/rotors and brackets, will these work on a 8.5 S-series axle end or will I need a rear setup from another 8.5 vehicle? Its kinda confusing because it seems to me GM used the smaller tubes from the 7.5 axle and flared it to attach to a 8.5 pumpkin. Am I correct? If so then any gear/cover or pinion parts, I would seek a donor or cross-reference a Impy, Caprice, C1500, etc for that stuff. And on the brake portions, I need any S-series, Astro, G or Fbody as a donor. Am I missing any possible donors and/or am I incorrect in my thinking? Ive been looking for a rear-disc donor for my T/A becuase when I get the Moser 12-bolt, it is set up exclusively to accept the OE disc and cannot be used with drums. If I find a couple of rear-disc F-bodies, I want to get the other parts too and put them on my S-series. Pending anyone has knowledge of this actually working. So...any input for any or all of this?? THX, Michel

[87wildside]

The GN drums are a bolt on. For the disk upgrade you could get the s-truck 2WD rear that has the disk already but since you have the 8.5 you should just get the brackets and such to convert yours over. They are factory pieces so you could price them new or look for a donor in the scrap yard. The backing plates and caliper brackets are the same regaurdless if is a 7.5/7.625 or 8.5.

[Hammer Head]

Could always use cadilliac rear discs from mid to late 70's sevilles.

[Mikz86TA]

There is a place on E-bay that sells cutom made caliper brackets that bolt to the axle tube flange to do a '79-'85 Eldorado brake calipers. They have these for S-series and F-bodies. But they say there is a need to turn down the flange to fit them. I am unsure if they are referring to the outter flange area(center hub) for the rotor to clear and slip over or the inner flange area between it and the axle tube. They dont seen to answer this clearly. But anyway.....So, for sure the S-series rear disc parts are interchangable from 1st and 2nd gen as well as 7.5 and 8.5 diFfs? What other than about 10lbs less mass are a benefit to alum drums. Its a cheaper route right now but still for $100 + its doesnt seem worth it to me. Also, another question, is there any premature locking problem on the rears(since it has little weight)with the disc setup on a orig drum system. Would i need a different proportioning valve assy from a disc donor and what about the ABS? ---------On another note I found some dual piston front calipers on a donor. I know I need the knuckles/spindle from a 2wd DP but the donor already had those removed. They left the calipers and I think one rotor. I am just gonna get the calipers and buy a rebuild kit for now. The rotors I might as well get a slotted set new. I just need to find a set of 2wd knuckles. Any problems seen there with prop. valve or ABS? And do you see anything I might also need in relation to the DP front swap? I appreciate the info. THX, MichelCould always use cadilliac rear discs from mid to late 70's sevilles.

[87wildside]

Check out s10warehouse on ebay, they have the daul piston spindles, rotors and calipers. I saw a listing the other day with 2" drop spindles. The aluminum drums just bolt on, you dont have to change anything else and I have never herd of any of the problems you mentioned. I would save the money for a disk conversion though. Hammer Head has some nice brackets to convert to C6 brakes for the rear listed in the classifieds, you just can't use your e-brake with them. IMO just stay with the S10 disk conversion in the rear, then you can trust all the parts, factory made and gov. tested. Also, parts will be easy to get.
If you have to have the center flange turned down for the caddy rotors what would keep the wheel centered? Not to safe.

[Hammer Head]

Nice plug Wildside, but I don't think Mike wants those since he has a 5 speed. But yea, I do.. & I second the plug for s10warehouse on ebay.

[87wildside]

Any time

[Mikz86TA]

Yeah Im gonna want to keep it from moving at rest and when I remote start it

[Mikz86TA]

I keep seeing them on E-bay but they are few. Good looking ones are going for over $100.00 which is too much for it right now. Im going to keep looking to get bids in for under $70