Will a '74 Electra rear (8.5?) bolt into a '72 Riviera?

I'm thinking yes, but wondering if others with experience can tell me if the bracket locations are the same.

And did the '74 Electra come with an 8.5 or 8 7/8?

Thanks!

Ken

 

Ken,
According to the '74 service manual, a 1974 Electra could have a standard ratio 2.73, a Limited Slip 2.73, Performance 3.23 or a Limited slip 3.23. It is a 9 3/8 rear end.

 

Hmmmmm......

Thanks for the replies. There's a board member here selling what he thinks is an peg leg 8.5 rear out of a '74 Electra. Sounds like no animal ever existed?

I'm waiting for pictures, maybe it isn't the original rear. These big car rears are a pain in the, well, rear!

 

As far as I know no animal ever existed, and the rear will fit into your Riviera.

 

Thanks for the reply, Trevor. If it isn't an 8.5, then there's no need to pursue it. I already have a 2.93 9 3/8 that I can't find parts at a reasonable price for. The search goes on for an 8.5. I believe I read a George N. post where I'd be looking for a 81 - 87 big car. I'll have to go back and find it to verify.

 

I'm confused, are you looking to put an 8.5 into the Riviera? If so, I don't think you'll ever find one that would fit, and without a fair bit of work would never hold up to the punishment.
Unless you plan on really getting into drag racing 2.93 is a perfectly acceptable gear set.

 

Trevor-

Yes I am looking to put an 8.5 into the Riv. There are several people on the board here, Nick Rabi and his Centurion included, that have successfully put 8.5's into big cars. He's been drag racing the car for a few years without problem and went this route as the usual 9 3/8 frustration with finding 3.42 gears and carrier (and all the year to year iterations thereof) make this route attractive- aftermarket support. I think Monzaz set-up his rear for him. I'd love to have a 9 3/8 3.42 posi rear, but that needle in the haystack is too hard to find (or I am just not patient enough).

My understanding is that the mounting points for big car rears from the early 80's 8.5 corporate rear and the 28 spline count make it straight forward to set-up and get parts for. The '72 Riv has two upper and two lower control arms, not the single upper and panhard rod like the late 60's Riv's had, so I am of the understanding that the right 8.5 from the right era is a direct swap. A TA girdled cover should also help strengthen the rear.

I will be putting a Trishield built motor in this car with a Trishield converter. Without a numerically higher gear, the converter won't approach lock-up until 80 mph or so, which isn't practical (even with some short tires- I did the math). Driving long distances with the converter slipping equals heat which equals trans failure ultimately. I also naturally want the launch the 3.42's will provide as the car will have some drag racing in its future.

 

There's a board member here selling what he thinks is an peg leg 8.5 rear out of a '74 Electra.

how certain is he that's its out of an Electra? if it's out of a Le Sabre it could be an 8.5" and it would work.

 

Yeah, and LeSabre's with 350's usually have 8.5" 3.08/3.23's in them.

 

it doesn't really matter what he "thinks" it came out of.

get the 3 digit axle code stamping, if i can't decode it i'm sure we can find someone who can.

 

That's what started this whole thread, Bob, as I'm in line to buy that rear. He posted that he's going to pull the cover, confirm ratio and measure the ring gear. Thanks!

He did confirm backing plate, spring perch, LCA, and shock locations are the same as those measured on my Riv.

I can only go up to '72 on axle decoding, if he comes up with a code.

 

Nothing wrong with the 8.5" rear end, although the 9 3/8 is definately stronger (but parts are hard to come by, as mentioned above). I've got one in my now-455-powered LeSabre, works just fine.

Riviera's and LeSabre's have the same chassis (and share other parts as well). 350-powered LeSabre's got 8.5 rears, while any 455-powered car got the bigger one - But from what I've seen, the LeSabre 8.5 would bolt right into a Riviera, and I'll bet an Electra as well.

Of course, the LeSabre 8.5 is too wide to bolt into a Skylark, although most (all?) of the internals will swap between housings.

Don't the 9 3/8 rear ends have 12 bolts on the cover, and 8.5's have 10?

 

But from what I've seen, the LeSabre 8.5 would bolt right into a Riviera, and I'll bet an Electra as well.

i've got an 8.5" in my Electra circle track car, have had for years. Le Sabre 8.5" compatibility is a known.

can't make any comment on drive shaft length.

 

Go Ken, Go!

(...and if you come across any additional 8.5 rears that fit let me know):Brow:

 

(...and if you come across any additional 8.5 rears that fit let me know):Brow:

look for any GM small block B-body from 1971-76. these rears were used across all 5 name plates.

 

No length adjustment required.

 

It has worked out well for me.I now need to replace my lower control arms with Metco billet arms as I have twisted up the lowers:3gears: Consider having your stock arms boxed, as replacing upper & lowers with the Metcos will run you $600.00.As far as I can tell,There are no stock replacements made.

 

A local yard has a 76 Electra that had a 455, and it has the 8.5". Both of my 76 LeSabres started life with 8.5" rears, so a direct bolt in 8.5" with bolt in axles is out there. 76 Buick B,C, and E models will almost all have one, as the 9 3/8" ended in 75. 77 up does not bolt in. Just avoid the Pontiac 8 7/8", which also has a 10 bolt cover. It has C-clip axles so the ends of the axle tube actually neck down a little instead of flaring out. I've swapped between the 8/5" and 9 3/8" using the same driveshaft every time.