Big Olds has a '70 GM 10 bolt, I think it's out of a Monte Carlo but it has Buick/Olds axles? FatAssBuick has offered me a posi rear from a Trans AM. Right now, the way the rear is set up, I have less then an inch clearance where the sidewall meets the wheelwell. If I have anyone in the backseat area it rubs. If this TA rear is a couple of inches shorter, will it be a direct bolt in and solve my wheel rubbing problem? If it's the same width should I just use the TA posi unit on the rear I already have? If I use the whole TA rear, what do I need to do to make sure it's ready to roll. I don't need any axle bearing problems. Anything else I need to be aware of regarding this swap??
I can't help you on the axle width/bolt-in question, but I do have a question. How big of a rear tire are you running? What is the wheel width? And most importantly, what is the backspacing? If you're running a wheel that is lacking sufficient backspace, one with the correct backspace could be the easy way out for you. Provided the wheel well will allow an inward placement of the wheel. A posi wouldn't hurt though. Might cure that 1/8 mile smokey run that was pictured a while back. Reason I ask is, and granted, wheel bearings at either end do fail for a myriad of reasons, but a deep wheel - or wide wheel with shallow backspacing, however you want to look at it, puts a lot of additional load on a bearing.
Was the Monte rear a direct bolt-in on the Big Olds? Another words, did you have the relocate the leaf spring perches on the Monte rear in order to fit on the Olds leaf springs? Measure the width from leaf spring to leaf spring (inner & outer) and make sure that the spring perches on the T/A rear end will line up with your leaf springs. If they do not line up, you will have to cut off the old perches and weld on new ones in the correct location. What year is the Trans Am rear end? (FWIW, a second-generation (70-81) Camaro/Firebird rear end is a direct bolt in for a 49-54 Chevy).
Denise, your rearend is probably the BOP 10-bolt, has a 8.2 inch ring gear with bolt in axles, no C-clips. Which means it was not out of a Chevy Monster Carlo. Most MC had 12 bolts anyway. If your rearend was out of a MC, then it should have the upper tabs on the center housing for the upper control arms, all the GM midsize had 4-bar type rear with coil springs. Although it very well could have leaf spring pads welded on and the stock lower arm mounts cut off. The TA rear, what year is it from? If a 70-81 (second gen) it is the "big" 10 bolt with 8.5 ring gear and is actually quite strong. The 70-81 has leaf springs, and the leaf pads may or may not line up with your Olds. But it is easy to cut off and relocate new pads. If the TA rear is from a 82-92, then it is the weaker 7.625 ring gear and I think you would be asking for trouble with the torque from your big block (455???). As for width, the 70-81 Camaro are about 61 inches wheel mounting flange to mounting flange. Probably similar to what you have in there right now.
The T/A rear end will not be a bolt in. The brackets will have to be cut off the current rearend, set up in a jig and welded on to the new rearend for your Olds control arms. Just Steve did a nice job of of installing the current rearend I wouldn't mess with it, it works it's been tested for 30K miles. Best to just replace your current open differential with a locking (posi) differential. You must find out which 10 bolt you have, it could be a 7.5", 8.2" or 8.5" 10 Bolt, and what gear is in it. I also think it's a BOP (Buick Olds Pontiac) 8.2 10 Bolt. GM 10 bolt differentials need a specific differential for the gear ratio being used they refer to them as a 2, 3, or 4 series differential. If the gear being used is a 3.23, 3.55, 3.73 it's a 3 series, if its a 2.56 or 2.73, it's a 2 series and so on. Kinda of hard for me to explain, maybe someone else can explain better I dont remember seeing any tags on your rearend. So it comes down to having to take the rear differential cover off to find out what's currently in there. You need to find out: 1. Which 10 bolt you have? 2. What gear is in there currently? Than you can probably dig up a posi differential here on the HAMB. Installation is a bolt in, but it's precision work. I've done a lot of Ford rearends but that's because I have the tools specific to those rearends. It's not usually a backyard mechanic sort of thing, I learned from my young early experiences of putting them together and grenading them in a months time because I didn't know how to set the pinion depth or backlash correctly. It may sound a little overwhelming but it really isn't, so don't let it scare you. Just ask for what you need help on. As far as the tire rubbing, you may be able to get a different offset wheel, if you have enough room between the tire and the inner wheel well. The rear tires are only a 235/70/15, not that wide by todays standards, If not your going to have to put narrower tires on it or raise the back end up a little, Steve said it had settled a lot, since he set it up.
Gus if I read you right The Big Olds doesn't have leaf springs, but has the trailing arm style rear with coil springs like what would be stock in the old monte carlo? SO if thats the case THe best thing would deffanatly just have a posi unit instaled in the current rear end.
there was many 8.5" 10 bolts with bolt in axles.all olds had them.from 71 to 77.but where coil spring.you can use the posi from the t/a if its a 8.5" 10 bolt but you cant put a posi that was originally from a bolt i axle in a c-clip rear since it needs a recess for the c-clips.show a pic of the rear cover,and im sure someone should be able to identify it. eric
[ QUOTE ] Right On! Stock 47 Olds rear suspension, long control arms and coil springs. [/ QUOTE ] Ohhh! Well then, that is a whole different animal!
WAIT a MINUTE denise. I have a rear out of a 79 t/a under my olds.. and I have a mile of room between the outer edge of the rear tire and the fender lip.. I think the clearance problem may not be what you think it is.. I believe you told me at york that you were running the chevy rear fenders on the rear, as opposed to the oldsmobile ones.. anyhow if clearance is an issue (to the outside) then you may just need to run wider rear fenders. If clearance is an issue to the inside (inner fender well) only when someone is in the back seat. a better solution may be to swap out the stock steel coil springs for a pair of air springs. thats way when someone (or in your case 10 people are in the rear seat) you can pump it up and raise the car! you know that you definitely have enough room for a tank and compressor with a car that big... later jeff
Nothing like being up at the CRACK of DAWN! Wich one is DAWN? Denise, see if the diff will swap to the one you have, then swap your rear wheels for a bigger offset. Cheapest and easiest solution.
I have a factory 4 bar rear end out of a GM car in my wagon.. HATE IT... I get so much side to side motion it can get scare at times...
InPrimer... so which one is your girlfriend??? Sorry, couldn't resist. Thought this photo might "entertain" you "monkeys" till I can actually take a photo tomorrow nite of Big Olds's rear and hopefully get it ID'ed. FatAssBuick sent me this link to help in the IDing process of my rear. The posi unit or whole rear end he is offering me is from a '79 TA. http://www.nastyz28.com/camaro/zsusp.html Thanks for all the insite. Wow, lots of info to digest. I think just installing the posi unit will probley be the way to go. Now, I just have to determine if FAB will fit or find another one. Jeff, yes, your remembering correctly. My rear fenders are the narrower Chevy ones. I like them better then the fatter Olds ones. I don't believe my wheels are rubbing on the inside wheelwell, just along the outside lip, therefore a new set of wheels with a different offset might work??? Yikes, starting to sound too expensive.
denise I have a extra pair of rear fenders that I believe would fit your car.. and if they do would answer a very important question for me.. I know you like the thinner chevy rear fenders but.. changing back to the wider olds fenders you'd gain space.. cheap!! my next question is this.. most likely when the car is "DOWN" your track bar (panhard) bar is pushin the axle to one side or another.. this (coupled with narrower rear fenders, and wider wheels and tires could be the problem) maybe the mounting point for the panhard bar could be moved to a point where when the car is loaded it wouldnt push the rear axle too far left or right.. as for the rear axle.. If I were in your situation I'd see if I could just swap in a posi center section..however be sure that the carrier in your current rear will accept the posi unit.. here's a pic of the rear axle set up in my olds.. using stock trailing arms. please note that in this view the car is all the way DOWN (axle is resting on the frame) also note the angle of the panhard bar and the position change which has taken place due to the travel of the rear. kep in mind that ideally the panhard (or track bar) should be level with the horizontal when at ride height (which mine is)
Okay, so...just to be clear on this....if Big Olds is running a 1970 Monte Carlo axle, then any 1968-72 GM A-body rear axle should bolt in unless the axle in the car has been modified, right? A-body cars would be 1968-72 Chevelles, Monte Carlos, Cutlasses, GTO/Tempest/LeMans, Skylark, El Camino, etc. MANY rearends out there for these cars, and a good deal of them will be 12-bolt axles. There is also some difference between "Chevy" rears and "Olds" rears. One will bolt in place of the other, however. My old big block 1970 Chevelle had an Olds 12-bolt in it. Said to be stronger, but aftermarket gears and axles aren't as common or as cheap. El Caminos were commonly equipped with positraction, and it was an available option on almost every car back then, too. Finding an A-body 12-bolt posi rearend might be your best bet. (It should bolt in to Big Olds unless I missed something???)
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