Mikes5thAve
Well-Known Member
Awesome info, thanks for posting that.
7.25 to 8.25
- Thread starter prowler
- Start date
prowler
Member
I don't know how many of you out there have done a diff swap like I'm doing. Since this had the 2.45's I had no
choice but to buy all new internals since I'm upping the ratio. I noticed what I'd call an unusual item related to
the 2.45 pinion. First time I've seen the following......After pulling the 2.45 pinion out of case I noticed that the
pinion bearing had a gap under the bearing collar between the bearing and the face of the pinion. It looks like
it wasn't pressed on flush the way as I've normal seen them. Either there's a machined lip the bearing is resting on
or it was for some reason done this way from the factory. Any body else seen this??
choice but to buy all new internals since I'm upping the ratio. I noticed what I'd call an unusual item related to
the 2.45 pinion. First time I've seen the following......After pulling the 2.45 pinion out of case I noticed that the
pinion bearing had a gap under the bearing collar between the bearing and the face of the pinion. It looks like
it wasn't pressed on flush the way as I've normal seen them. Either there's a machined lip the bearing is resting on
or it was for some reason done this way from the factory. Any body else seen this??
Shorty Thompson
Well-Known Member
Why? Just find a " B " body 83/4 and be done with it.
prowler
Member
Putting an 8-3/4 under an M body car is more of a major under taking. NOTHING interchanges. I'm doing this job because after all these years, I am sick and tired of putting this car into gear and hearing that enormous destructive clunk in the running gear. Besides it's a 318 cruiser and I have no intention or need of this car being anything more.
Mikes5thAve
Well-Known Member
8 3/4 has 3" axle tubes and uses the same backing plate as 8 1/4 and later 7 1/4 so in the end its the same amount of work but harder and more expensive to find the axle itself... well harder to find might not be true anymore since M bodies have been gone for so long now.
prowler
Member
Sorry,..I'm not going to agree with it being the same amount of work. FMJ's came with 8 1/4 and if one has the proper parts, it a bolt in. 8 3/4 is a custom fit and there will be ALL the required work a custom install requires. Plus,...unless you've dropped a high HP engine into one of those it's overkill.
Mikes5thAve
Well-Known Member
You said going 8 3/4 is a major undertaking because nothing interchanges but nothing has to. Ok, with the proper sized 8 3/4 there is a bit of extra work. Like what drilling out the holes bigger?
I do agree it is over kill for what most people do to these cars I'm not arguing that part.
prowler
Member
Well,....the bottom line here is that installing an 8 3/4 in any FMJ body is a lot more work all the way around.
Mikes5thAve
Well-Known Member
It's a bit of extra work. On a car that already has the bigger axle tubes its a fraction of the work you had to go through to get the 8 1/4 in.
Shorty Thompson
Well-Known Member
I whole hardly disagree. I ran many of these cars in demolition derbys and it isn't that hard . What's the major issue? cutting the driveshaft down to fit. The springs are almost a a perfect match outside the certering pin. Replace with O.E. 8 3/4 problem solved.
Shorty Thompson
Well-Known Member
Agreed same " Brake backing plates " 8 3/4 does have the same brake backing plates. With that being said and if you pay attention you can have disc brakes back there.
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prowler
Member
I'm not going through all that cost and setup for this project. I wanted what amounted to as a factory bolt in unit. A Mopar guy in my neighborhood purchased a real nice 86 New Yorker and is intent on putting an 8 3/4 under it. It's not going to be any bolt in but he intends on making what ever modes he has to make.
AMC Diplomat
Well-Known Member
For the people in the future who stumble across this thread:
You can absolutely swap B Body 8 3/4 axles into the cars for about the same effort as any other rear axle change. There are literally dozens of threads about it here.
The best way to search this forum is a Google Search. You type in "forfmjbodiesonly.com" and whatever topic you're looking for information about. Try a Google Image Search too. The search function on the forum itself is pretty limited.
You can absolutely swap B Body 8 3/4 axles into the cars for about the same effort as any other rear axle change. There are literally dozens of threads about it here.
The best way to search this forum is a Google Search. You type in "forfmjbodiesonly.com" and whatever topic you're looking for information about. Try a Google Image Search too. The search function on the forum itself is pretty limited.
prowler
Member
Yes,.......about the same effort as any diff that never came in a particular model. It's never going to be a bolt in as factory.
Mikes5thAve
Well-Known Member
It's by far as easy as you'll ever get putting in a non stock rear. Drill out a couple holes bigger and it will bolt in the same as any factory rear.
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CORSAIR
Member
I think you guys are maybe missing a bit of the point with going to an 8.75 over the 8.25. I can completely agree that it's a better, stronger axle with good parts support but it's far more expensive to find out right and parts are more expensive even when you do find an axle.
As an example; You can get a drum to drum complete 8.25 out of a late 90s Jeep Wrangler off eBay for about 700$ shipped and those don't need narrowed and may not need rebuilt. Parts are about half of the cost and just as easy to get. Any 8.75 is going to be about $3k and may not be complete and may need rebuilt/narrowed. Behind a stock or moderately modified driveline of one of our cars, the 8.25 is more than strong enough. The 8.25 is the more economical choice and no less of a pain to get installed.
As an example; You can get a drum to drum complete 8.25 out of a late 90s Jeep Wrangler off eBay for about 700$ shipped and those don't need narrowed and may not need rebuilt. Parts are about half of the cost and just as easy to get. Any 8.75 is going to be about $3k and may not be complete and may need rebuilt/narrowed. Behind a stock or moderately modified driveline of one of our cars, the 8.25 is more than strong enough. The 8.25 is the more economical choice and no less of a pain to get installed.
Mikes5thAve
Well-Known Member
Most of us probably agree that an 8 3/4 is overkill but the specific point that was brought up was the opinion about how it is so much more work to put one in vs an 8 1/4 when it's not.
I dont remember if jeep one is a direct bolt in or needs any modifying I think most people here usually look for an M body 8 1/4 or proper year range B body 8 3/4 so that you're starting with something that's going to fit to begin with because in most cases it's really not worth getting into when you have to get it narrowed or have one custom built. Unless you have some crazy engine build or car use.
M body 8 1/4 fits just right, not any more work or effort than a ‘68 8 3/4 though. If you want improved handling and are thinking of adding rear sway bar and better shocks, B-body parts are the way to go for availability and support anyway. between buying and shipping and getting the rebuild parts I was over $2000 in my 8 1/4 inch. Can find a ready to run ‘68 rear end in most areas for that.
I’d do a Ford 8.8 if I was really going to make real change to the car.
I’d do a Ford 8.8 if I was really going to make real change to the car.
