Switching from 8-1/4" to 8-3/4" rear ?
- Thread starter RPMagoo
- Start date
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cycle31
New Member
1) A 8 3/4 rear and possibly leaf springs
2) A set of 8 3/4 shock plates and U bolts for new housing.
3) New Shocks
4) possibly new rubber brake hose to brake line
5) New Rear wheels and tires going from 5 x 4 SBP to 5 x 4.5 BBP
6) new drive shaft and new U-joints.
7) *** tools and Alot of patience installing
Did I miss anything?
2) A set of 8 3/4 shock plates and U bolts for new housing.
3) New Shocks
4) possibly new rubber brake hose to brake line
5) New Rear wheels and tires going from 5 x 4 SBP to 5 x 4.5 BBP
6) new drive shaft and new U-joints.
7) *** tools and Alot of patience installing
Did I miss anything?
RPMagoo
Just An Old Motorhead
-- Already have 5 X 4.5 BBP, installed, and running. -- Thanks for the info.
mad accountant
Well-Known Member
You won't necessarily need new rear wheels, if your new 8 3/4 is SBP, nor will you need a new driveshaft if the one you have can be cut down and balanced. Hopefully another will chime in about whether or not you'll need to have the 8 3/4 narrowed or not and/or the spring perches relocated.................................... A second set of hands is always nice to have, too.
72Dart6pack
Harder Better Faster Stronger.
To go from an 8.25 to an 8.75 you will need replacement SBP wheels (unless the 8.75 has replacement LBP axles in it). You can reuse the shock plates and might be able to reuse the U Bolts (but I would probably use new). You might be able to reuse the brake hose but again, I would replace it. You might be able to reuse the rear U Joint depending on what's on the 8.75 pumpkin. Check the oil level in the 8.75 after installation.
72Dart6pack
Harder Better Faster Stronger.
Just call me. I'll walk you thru it.
abodyjoe
Well-Known Member
So ya have an abody 8 3/4 with large bolt all ready to go?
Rear will bolt right in. I'd use new ubolts. Need to shorten the drive shaft I believe and make sure the rubber brake line will work.
What's wrong with the 8 1/4?
If the 8 3/4 is BBP all you need is to shorten the driveshaft and match the U-joint to the yoke. For those that don't know all the 8.25's are BBP.
New u bolts are a good idea unless they're fairly new already. Shock plates are the same, brake line should work fine. Springs are the same, shocks are the same, brakes are the same if the 8 3/4 is really BBP (and not just redrilled), none of that of stuff NEEDS to be changed to swap from one to the other. Although if any of it is old now would be the time to change it, when it's all apart already.
New u bolts are a good idea unless they're fairly new already. Shock plates are the same, brake line should work fine. Springs are the same, shocks are the same, brakes are the same if the 8 3/4 is really BBP (and not just redrilled), none of that of stuff NEEDS to be changed to swap from one to the other. Although if any of it is old now would be the time to change it, when it's all apart already.
72Dart6pack
Harder Better Faster Stronger.
It's way too much work. Just sell me the car & save your money. Lol
Also worth mentioning is the rear axle width. An A-body 8 3/4 with BBP axles and brakes is about an inch wider overall than an A-body 8.25. So, your backspace will change by about a half inch per side. If you're running tires that are perfectly centered and maxed out for width already you may have an issue with not having enough backspace with the BBP 8 3/4.
So take a look at your tire to quarter clearance and see if you have a half inch or so to give up. You'll need about a half inch of clearance to keep the tires from rubbing on the quarters when you're done.
So take a look at your tire to quarter clearance and see if you have a half inch or so to give up. You'll need about a half inch of clearance to keep the tires from rubbing on the quarters when you're done.
RPMagoo
Just An Old Motorhead
-- (1) No - I'd have to buy it, from a friend. -- (2) Nuttin -- Probably, won't do it.
ValiantOne
Well-Known Member
If the 8.75 is an A body unit, and has a limited slip chunk and/or had a more desirable gear ratio, I'd do the swap. NOTHING wrong with the 8.25, but the 8.75 is a bit more stout, so it it also has the other attributes listed above, I'd do the swap. It ain't hard! I'm loving my upgraded 8.75 rear. With the hp I'm running I can hammer on it all I want, I have a better gear ratio, i now have lbp axles, etc.
Mopar Al
MOPAR AL
DELETE THE SHOCK PLATES
Also, you will need the ability to bench-press about 250lbs.....
Jeff
Jeff
bkmcoolhand
Well-Known Member
Where are u located? I'd be interested in the 8.25 when you switch out. I'm in Atlanta.
RPMagoo
Just An Old Motorhead
-- I'm not doing it. -- Thanks
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