So I have a '57 Poncho rear under my '55; It's been under it since the 60's. It's a 5.13 with a posi; which, in case you were unaware, is worth a fuckload of money. Here are it's issues: While the likelihood is very low, I don't want to break it. It's definitely not a highway friendly gear. Lately, the axle seals have been leaking, BAD, and replacing them only fixed it for one season (they're actually sealed bearings, so it's not a super easy repair either!). Because of the leaky axle seals, the rear brakes don't work, and stock front drums only with 5.60-15's, and 100+mph speeds aren't that great of an idea. I haven't busted out a tape measure yet, as I haven't had time, but I have a few different rears that I could throw under it, and I was wondering which would be the best compromise (amount of work involved vs amount of cash involved vs strength vs appearance, etc) for now... Something in the 3.90 - 4.11 range is what I'm after for the current motor/trans. Any of them are going to at the least require different back wheels (due to bolt pattern), so getting a different offset to accomodate slightly different widths shouldn't be a big deal.. I have a few 9'' rears around, but they're mostly all crappy ratios and one wheel peel. I do have one that has brand spankin' brakes on it, so that's a plus. The one I'm leaning toward is a 8.5" 10 bolt out of a '75 Camaro. It came out of a running, driving car, so the brakes should at least be salvageable, plus, it's got a Richmond 4.11 with a posi, and the gears and clutches look PERFECT. The biggest (only?) downside, it looks like a 8.5" 10 bolt, which looks GAY under a 60's era drag car. How close to a "bolt in" would the camaro rear be? It's not like moving leaf spring perches is a big deal, but less work is less work, especially when I have ZERO free time. What about drive shafts? How much of a driveshaft length difference should there be from a '57 Pontiac rear to a 9" to a 8.5" 10 bolt? Let me know what you guys think... Thanks in advace! Steve
find a stock 55 driveshaft and don't worry about that part of it. Width should be very close to stock. In case no one else says it, I'll get it over with: YOU'RE NUTS!!!!
Just my opinion,but I'll never give up the 57 Olds axle in my 57 Chevy delivery. Why not just buy a 4.11 gear for it and throw some new seals in it? I never really had an issue with leaking axle seals but I recently replaced them while I was swapping in a 4.56. Are your axles rusty where the seals ride? You do realize the seals are inside the axle tube,right?
Cuz that's a $450 bill that I don't have right now, and I'll be PISSED when I break it! Mine had sealed bearings with an O-ring on the OD of the bearing to seal in to the housing, and then a gasket behind the retainer plate... there was no seal in the tube, so I didn't put a seal in the tube.
Well I've learned something then. I always thought the Olds/Poncho were the same but as you point out and Fabcraft Metalworks seems to verify that the pre 59 Poncho's are different.I knew the pre 59's had smaller axles and there was a slight width difference Pontiac to Olds but never knew they used different axle bearings. I stand corrected. BTW Fabcraft Metalworks seems to have the largest selection of parts for these axles. Much more available now than 20 yrs. ago. http://cgi.ebay.com/ebaymotors/1959...62QQcategoryZ34208QQihZ025QQitemZ380040069538
Don't listen to the camaro "it's a direct bolt in" bull line. camaro rears are NOT direct bolt in as they are above the spring rear end while yours is below the spring mountings. They are an excellent choice for size, but you'll need to cut off the old spring perches and weld on new ones. And the old spring perches on camaro rears are NOT easy to cut off as they are completely welded in three locations.
Ummm....the 56' Olds/poncho rear I had was a spring under setup, same as the camaro 8.5" rears. The camaro spring perches are different and should be cut off and replaced. I don't know if they are in alignment for a bolt in. Also, there should be a seal inside the axle tube also IIRC. We just did leaky seals on a 57' Pontiac and it had them, as well as the o-ring on the sealed bearings. A stock 55-57 chevy rear is about 60" A 2nd gen camaro rear is 62.5" A first gen camaro or 68-79 Nova rear is 60"
Actually the 57 pontiac/olds rear with leaf springs is a direct bolt in on the 55 thru 57 chevy. Put many under my tri-five race cars over the years. They are slightly wider 1/2" (1/4" each side). the bolt circle is 5 on 5. Fabcraft in Texas is a great choice for parts. Contact Brad @ Fabcraft 800-208-8242, he is very knowledgeable. I just finished puting a 57 olds rear together for my 40 coupe, w/3:42 gears, it cost me way less than building a equal 9". Anyways I would keep what you got and changes gears and put new seals in.
just one simple question. will a 1953-4 pontiac rear 3rd member fit my 1956 oldsmobile rear axle. found one for $75 need to know before i buy it and it wont fit. thanks
1st generation Camaro or Firebird is the same length. The only change would be the spring perches. The 75 rear is going to be about 1 inch longer per side. I've got a 81 in my 55 and without cutting the wheel wells it was a bitch getting the right tire- wheel combo with some dish in the smoothies. I ended up with a 4:10 rear and 29 inch tire (235-75-15) on 7 inch smoothies and even then I can't put the damn tires on the car unless they're put on flat and then inflated. It works ok but after so many tries I gave up and went with it
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