: SS rear end swap



dretwenty5
02-18-07, 08:39 PM
Will a rear end from a Impal SS bolt right into a Fleetwood. I know there maybe minor modifications, but what about the overall length of the rear.

90Brougham350
02-18-07, 09:08 PM
Search the forum, there was a thread about this not too long ago. Also, have you checked out the Impala SS forums?

96Fleetwood
02-18-07, 09:26 PM
It will not bolt onto a 1993-1996 Fleetwood. The rear end of the Fleetwood is wider than the Impala SS.

Are you looking to do a gear/posi upgrade and rear disc conversion?

If so, there are plenty of ways to do that. There is a kit for the rear disc conversion and most upgrade to the 3.73 gears and Eaton Posi. :thumbsup:

509Rider
02-18-07, 09:43 PM
It will not bolt onto a 1993-1996 Fleetwood. The rear end of the Fleetwood is wider than the Impala SS.

Are you looking to do a gear/posi upgrade and rear disc conversion?

If so, there are plenty of ways to do that. There is a kit for the rear disc conversion and most upgrade to the 3.73 gears and Eaton Posi. :thumbsup:I was told by a bunch of guys on the impala ss forums that the ss rear was wider than the fleet.:hmm::hmm:

dretwenty5
02-18-07, 09:54 PM
Yea I want to do the disc conversion as well as the posi/gear upgrade

N0DIH
02-20-07, 09:03 AM
Rear end BOLTS in fine, but you LOSE Traction Control and ABS.

The Impala SS/9C1 Rear end is mice nuts difference in width, so don't worry there. The problem is the Impala uses a 3 channel ABS, the Fleetwood uses a 4 channel AND traction control (which is what also requires discrete sensors on each wheel). If you get a hold of Bill Harper (NavyLifer) on ImpalaSSForum.com he can sell you the parts needed for the conversion to convert your exists rear end to the discs.

Now, the performance of the discs isn't really that much better than the existing drums. There is the looks and the discs do better at heat dissappation, so they resist brake fade better.

After looking at it a couple years ago, I feel the conversion is far better than trying to swap and lose TC/ABS. If you get a rear disc axle for a good deal, you need the parts, but you will need to send the backing plate to Bill to be machined.

Basically all that is needed is the discs, backing plates (modified by Bill), new brake lines to connect up the existing lines to the calipers.

You can buy a posi unit from any GM 8.5" axle (ANY, but Eaton is best and OEM type, uses clutches not cones like Auburn) and have it installed with your existing gears for around $250. New gears might be worth it for performance and a good time to do it. Note 307 cars often had 7.5" rear ends, so you will need to use 7.5" posi unit. You CAN use 82-2002 F-Body parts, often posis, but in reality they are 7.625" and you can't swap CARRIERS (the posi unit) and keep a 7.5" ring gear. I bought a used set of 3.23's from a V6 Camaro shipped for $65 some years ago, but open diff.

Adam
02-22-07, 01:07 PM
haha, wow, three different answers.

No its too small.

No its too big.

Yes it fits fine.

GET IT RIGHT PEOPLE! :bigroll:

N0DIH
02-22-07, 01:24 PM
As long as you don't use a wagon rear you are ok, they are significantly wider. The rest are like 1/4" or less. AND the control arm mounts are the same locations.

BCs71
02-22-07, 06:16 PM
NODIH speaketh the truth.

Navy Lifer
08-03-07, 07:53 PM
It's been a very long while since I visited, but this is still of interest and possible value to some of you. Realize it's an old thread, but thought I'd throw in my 2 cents....

The rear disc conversion is still viable and available for anyone interested.

As far as swapping rear axles, the 4-channel vs 3-channel ABS issue creates a parts matching problem. Housing and axle shafts for the 4-channel system on Fleetwood pretty much dictate keeping it, however, with a little work, a Roadmaster or Caprice "narrow" 8.5" (ring gear size) housing could be used, along with the FW axle shafts..

The axle assembly width for Fleetwood, Roadmaster, and some Caprice models, including 9C1 with rear discs, was 1566mm. Impala SS was 1598mm, wider by 32mm, or about 1.25", which the Fleetwood body cannot accept, unless some creative wheel/tire work was done at the same time.

N0DIH
08-03-07, 07:57 PM
Good info, thanks! Especially for Fleetwood owners.

I just picked up a 95 9C1 for parts and got the rear end as a bonus (we bought for engine...). Not sure what my plans are, but at least I have some goodies to play with....

Do you know why they widened the axle width for these cars only?

Navy Lifer
08-04-07, 12:24 AM
Do you know why they widened the axle width for these cars only?


No, I don't know specifically why, except as a cosmetic issue--and I can only say that as an assumption.

When the wheel openings were changed for 1993 Caprice, the wider axle was added, since the 91-92 design required the "narrow" housing.

It may have been part of the introduction plan for the Impala SS, which debuted as a SEMA "dream" car in 1992, and axle width may have been adjusted accordingly to achieve the "look" of the prototype, even though the SS did not begin actual production until mid-1994--wider axles were ready and waiting, and some 1993 models got them--typically the B4U cars, with G80 and 2.93 axle ratio.

I also think the 9C1 cars stayed with the narrower axle to ensure adequate clearance for chains, a typical emergency vehicle requirement. The 5/8" per side gave more equal frame and fenderclearance on both the inside and outside of the 7x15 wheels. Chains were not a concern, nor do I believe were they recommended, for the Impala SS with 8.5x17 wheels