Caprice Rear End Swap ???'s

by Sleddogg Tue Apr 23, 2013 1:20 am

Looking at posi rear end from an '88 Caprice. From reading the interchange thread, it appears that it should fit, to replace my 8.5 10 bolt in my GP, however the Caprice has a 5x5 bolt pattern according to the recycler's website. I would like to keep my 5x4-3/4, the same website says that 1988 Caprice axle shafts will interchange with my 10 bolt. Anybody have any experience with that? I really hate to have to buy different wheels, and would rather just swap my axleshafts over to the new rear, as it should be 28 spline still? Sometimes those websites aren't the most accurate. Any help appreciated. Thanks!

by dynchel Tue Apr 23, 2013 7:18 am

I think that by '88 the spine count on the axles went to 30 (from the original 28). I am not 100% on this though. Maybe someone else can chime in.

by 1973 454 MONTE Tue Apr 23, 2013 7:35 am

i have an 86 caprice and its 4 3/4 bolt pattern
Caprice Rear End Swap ???'s Capric10

by dynchel Tue Apr 23, 2013 7:37 am

I think police cars and wagons got 5x5.

by thatfnthing Tue Apr 23, 2013 9:47 am

Sleddogg wrote:... however the Caprice has a 5x5 bolt pattern according to the recycler's website. I would like to keep my 5x4-3/4, the same website says that 1988 Caprice axle shafts will interchange with my 10 bolt. Anybody have any experience with that?

FWIW, here's an alternative: there are adapters out there to switch between any bolt patterns -- I have 5 x 5 lugs on the front (Caprice rotors) and 5 x 4.75 on the rear (stock axles) and am running wheels that are 5 x 5.5. The adapters come in many thicknesses, but the minimum is 1", so you will need to take that into account in conjunction with the width of the axle hub-to-hub and the backspacing on the wheels. My wheels have enormous backspacing, so the thickness of the adapters actually puts them right where they need to be in the wells.

by Limey SE Tue Apr 23, 2013 10:11 am

Can also take to a machine shop they cam machine it to a 4.75 pattern as well

by Sleddogg Tue Apr 23, 2013 11:51 am

Thanks for the replies.

The adapters... that's a great idea...one of those "why didn't I think of that" things Smile

This particular caprice was a cop car so it does have the big bolt pattern. Not sure on the axle splines, may be 30 spline...either way I think they adapter would be the way to go.

Hopefully I can get out and check this thing out in person today. With the luck I have been having lately, afraid I am gonna see a bunch of garbage with a worn out auburn posi Sad

Maybe I will catch a break...

Thanks gang

Jesse

by alleyball4 Tue Apr 23, 2013 2:02 pm

yes, the caprice rear end is a 30 spline, as opposed to our 28 spline.

the easiest thing to do, if you buy an aftermarket wheel, like a Weld Draglite, is to make sure you have universal bolt pattern, so the 5 x5, or the 5 x 4.75 will both fit on the rims.

If you are running a bunch of horsepower, the wheel adapters are not the way to go.

If you redrill the plates to the 5 x 5 bolt pattern, youre going to spend at least $50 in machining cost.

Other than that, everything else lines up, as direct fit.

If you have more questions, call Moser rear ends ... they are on the Indiana/Ohio border, and specialize in answering rear end questions.

by Limey SE Tue Apr 23, 2013 2:09 pm

Jesse a member here is offering a Caprice one already done and ready to Install

Brownbomber is his Name

entire rear end out of a '96 Impala SS. It is a 3.08 eaton posi with 80,000 miles on it. It has disc brakes. it was drilled for 4.75 bolt pattern by my machine shop. The rubber bushings are not cracked or dry rotted and the fluid was still gold when I drained it. All the brake lines are all intact.
Thanks,
Dan
815-298-2912

by thatfnthing Tue Apr 23, 2013 2:29 pm

alleyball4 wrote:If you are running a bunch of horsepower, the wheel adapters are not the way to go.

That didn't take long.

Unless you are making stupid power, they work fine. They use standard wheel studs. If you're making enough power to break them, you're making too much power for your stock wheel studs anyway. Been running them for years and never had an issue, and I light 'em up frequently. Most people break them because they forget they need to be retorqued periodically just like the wheels. If they're loose, you're guaranteed to break them.

by alleyball4 Tue Apr 23, 2013 4:15 pm

you're right, if youre not running a bunch of horsepower, the wheel adapters should be fine.

by Sleddogg Wed Apr 24, 2013 12:03 pm

Well that was a bust...

Axle looked like it came out of the La Brea tar pit, and the posi unit was missing. I hate trying to do stuff with a shoestring budget. Did find a yard here that would sell me '96 disc brake posi unit from a Impala SS....only $650 bucks Shocked

....about choked when she told me that number.

Since the 8.5 ring gear stayed essentially the same all the way up into the 2000's....even the 8.6 will work in a 8.5 carrier, Ebay has people selling stock ring and pinion take outs pretty cheap. Might just upgrade the gears now and later on work on a posi, or a lunchbox locker...something along those lines, unless I just fall into some sweet deal somewhere along the line.

by Sleddogg Sun Jun 23, 2013 12:53 am

Patience is a virtue.

Just drug home a 3.23 posi out of a '92 caprice.

$40 bucks.

Lucky day finally Smile

by bitterfitter Sun Jun 23, 2013 3:09 pm

I did a rear axle swap from a 1995 impala police car to my 1974 malibu. If I remember right the bushings are slightly different in size. I think the brake lines are a different thread also. They were metric or something? Sorry I can't remember but I made the conversion where the brake line from the car goes into the block on the rear axle and slips to two. I just had my local hydralic shop sell me the adapter. Also the 5x5 pattern on the axles, obviously....

Classic tube is located right here near Buffalo and I had them make me a set of stainless lines for the axle. I should of just had them put the correct threads on the end of the lines and been done with it.

To this day I still have not tackled the problem of getting the parking brake working. And I will have to if I want the car to pass inspection!

by Sleddogg Mon Jul 15, 2013 12:50 pm

Finally got around to taking a good look at my posi rear end...

It's out a freakin wagon....LCA mounts are about spread out further about 2" difference and the spring perches have a difference of about 1". So, IF I could coerce this thing under my GP, my spings would sit canted and I would have LCA's that were at an angle which I imagine would be no good. Not to mention that the entire axle is 2 1/2" wider.

Damn shame too, cause the posi in this thing is good and tight.

This is a frustrating situation.

by McCauley5983 Sat Sep 21, 2013 12:08 am

Just swap the carrierand axles I was told it is 150 to machine axles to right bolt pattern if I pull them and reinstall them. Wheel adapters are anywhere from 150-300 bucks

by thatfnthing Sat Sep 21, 2013 1:10 pm

billy-ray wrote:Wheel adapters are anywhere from 150-300 bucks

$75.00/pair at ezaccessory.com. Billet aluminum.

by brownbomber77 Tue Oct 22, 2013 10:51 pm

The the center brake line threads are the same from the '94 Impala rear end to my '77 Cutlass.

by brownbomber77 Sun Aug 03, 2014 3:47 pm

And another thing, I just discovered that ONLY the 89-90 CAPRICE had 30 spline axles and 5x4.75 bolt pattern. If you can find them used anywhere, that'd be the way to go. I found one set on Ebay, $41 each shipped.

by brownbomber77 Tue Oct 07, 2014 11:09 am

Aaaand one more....the B-body wagon's will NOT fit our cars unless you move the spring perch in 3/4 of an inch. inward toward the pumpkin.

by 99B4C Mon Jan 12, 2015 8:19 pm

When I had a 95 Caprice rear end installed, the 73-77 lower control arm bushing is too narrow (it could be shimmed with washers) and the ID is also incorrect. I used a Moog lower control arm bushing for a 68-1970 something Thunderbird and LTD. It has the correct 73-77 od for our control arms, and the correct Caprice ID and width.

by brownbomber77 Wed Jan 14, 2015 7:57 am

Wow, that's useful, kinda cool. I was just going to shim mine now that the urethane bushings are already installed, but things to ponder in the future.

by pila Wed Jan 14, 2015 5:27 pm

Seems like there is no simple or cheap way to get what we want to fit.
I have a 9-inch Currie in my Elco, and the upper control arms just don't fit up the way I think they should.
I had no problem adjusting the pinion angle, but not sure of the up-down travel of the rear end. Had to make one ( right side) shorter to get it to bolt in there. Currie was no help either. I'll likely be doing some major mods on it, or get a housing from another supplier. If that doesn't get it, the 8.5 10-bolt will get put back in there, and make another drive shaft to fit. Then I would need a stiffer spring on the gas pedal.....

by Joe73 Wed Jan 14, 2015 5:57 pm

As for the up and down travel of the rear. I like to support the frame in front of the lower control arm mounting points with jack stands. Then remove the bottom shock bolts so the shocks hang. Put a floor jack under the diff and remove the springs. Then I jack it up all the way and lower it down all the way checking that its free to move through the suspension arc easily.
Thats what I did when I installed my poly bushings in the rear (new rubber in the diff ears). Just to make sure the suspension was operating nice and smooth with the new bushings.

Just a thought.

by pila Thu Jan 15, 2015 12:29 am

Thanks Joe ! I'll try that ! Just didn't think about doing something without the springs in there! Very Happy

When the weather warms up I'll get into it again.
I have to get it up to remove the leaking transmission, so it would be the time to do it...

Bill

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