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57 Chevy Rear?
Hello All,
What type of rear end was the stock unit for a 57 chevy? The numbers that are clean enough to read on the case are: GM 3726886 (the 8's and the 6's are kinda hard to read after 40 years. Jegs catalog claims it is a 8.2" early 10-bolt. Does this sound right? thanks in advance |
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Yeah thats the one!
From behind it has no bolt on cover. Looks very similar to a early 60's mustang rear. The gear ratios available from Jegs... 3.73 and 4.11 10-Bolt 8.2'' (Early Model) 8.20'' Diameter Ring Gear 1.438'' Pinion Diameter 17 Spline Pinion 10-Bolt Oval Housing Fits: 55-64 Chevrolet, 55-62 Corvette The problem is: I can chance either of these units... I would prefer the 3.73 but I am not sure if it will work with my current setup. Also, is there any uniqueness to these rears that make them inheritantly harder or easier to rebuild? - Im not looking for performance, just reliability. I am pretty sure it is an original unit due to the rest of the driveline being from that era... ie 3 spped tranny and a (well... 1958) 283. -one year off... I cant believe how difficult info on that unit is to find online... Its almost as if chevy rear ends were not made before 64
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You think that is tough to find parts for, try running a '56 Olds rear end! At least someone still makes new gears for the Chevy.
They are very easy to work on. If you are familiar with the basic principles of rear end setup, these are plain vanilla. You didn't mention what your setup is so it is hard to comment on what ratio is the right one. If it is a daily grocery getter, 3:73s are on the upper end of practical ratios for a non-overdrive tranny but great for an OD unit. If it is a warm street/strip car, 3:73s are perfect. if it is an all out drag racer, go with the 4:11s. Incidentally, if all you want is a cruiser and aren't interested in performance, why are you considering changing ratios? Why not keep the gears that are in it now? |
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hey thanks for the info...
Actually, the setup is going to remain stock. I dont care about performance, i just want it all to be new and reliable. I would be quite happy with a 3.00 rear end... just for cruisin. I havent popped open the case yet to see what shape the gears were in... I was kinda thinking that they might not be in the best shape. Odometer reads 30,000 so either thats 130... 230... or who knows. When i got the car there were also traction bars under it so I was thinking they may need replacement... Typically how many miles or how much abuse do rear ends take before they need replacement? I know its all relative. If things look good would you just do seals and bearings and just give it all a good cleaning? |
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Sans - you are correct in assuming the gears may be in good shape. If it were mine, I would take out the third member, clean it up and inspect the gears. If OK, slap it back in with new seals. If there is no noise the bearings are probably still fine. If in the future it starts making noise, you can always re-bearing and re-gear. Since it is a cruiser, not a racer the thing will probably last longer than you do! Obviously if you find metal shavings or other big problems when you get in there a full rebuild is in order.
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Sans, I am currently running two vehicles with this rear end family. One is a 57 vintage that had 64,000 miles on a 3.36 gear when it went in my PU in 1978 and I had it re geared recently and posi added. The old unit had a total of 271,000 miles and was still good. The other unit is a 64 that I just had rebuilt with all new stuff (3.08 ring and pinion set, bearings and seals) I don't know how many miles were on it because it came out of a junk yard dog several years ago.. pretty worn and teeth were pitted and becoming noisy. Even though the ring gear is 8.2' in diameter, according to the professional gear guys, this family of rear ends are referred to as the 8.8 in their trade. My telling them it was an 8.2 over the phone resulted in them ordering the wrong gear set!! By the way, there are 10 bolts in the housing and you would think it would be the 10 bolt that is often referred to!
Trees |
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Im going to give it the once over this weekend. If it is in good shape, my next challenge is going to be to find a place where I get new seals...
Hey thanks again for all the informative replies! |
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If the seals are gonna be a pain to locate theres this sheet of gasket material most stores like autozone sells...what you do is use your old seal and use it as a template and trace it out..cut it and vwala...a new seal..hope this helps
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If you are pulling the pot out, count the gears to get the ratio. Chances are, it's a 3.36, most of the ones that I have had were. If it's a 57 rear end, it will have a drain plug on the bottom. 55s and 56s didn't have this.
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Ontario Rodders |
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If it was a 'glide car originally, it'd probly have the 3.36's. If it was a 3-speed, I'd bet on 4.11's.
Seems like I've seen ads, for 3.55 replacement gears, but it escapes me where I read it. |
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