Anyone look at an XJ cherokee rear end for a BBP conversion?

-
michiganpat

michiganpat

Well-Known Member
Joined
Sep 1, 2023
Messages
233
Reaction score
124
Location
Grand Haven, MI
Hey guys,

I'm looking at options for my duster when I do a front disc brake conversion to get the BBP in the rear. I'm reading through the ford 8.8 thread, but I also had an epiphany late last night. I looked it up, and an XJ cherokee has the 5x4.5 bolt pattern, a centered pumpkin, and a 59.5" drum to drum width, so about 2" wider than an A body rear, but an inch narrower than a 68-70 B rear. they came with dana 35's or corporate 8.25's. looks like manuals came with 3.07 gears, autos with 3.55's and tow package with 3.73's.....

looks like all you would need would be a 7260/1310 conversion U joint and getting the driveshaft shortened to the right length....

has anyone done this swap, and can you think of a good reason not to use an XJ 8.25 in a slant 6 or mild V8 duster?

Thanks,
Patrick
 
Last edited:
When I was looking into this (I had an XJ at the time), I came up with a with an overall width right around 60". This compares to the A body 8.25 at 56 3/4, or the '68-'70 B body 8 3/4 at 60 1/8" overall.
An accurate 8 3/4" rear axle width list
Since this puts it at a nearly identical width to the B body rear (which is a common swap into an A body), I see no reason not to consider it. Confirm the XJ's measurements yourself at the boneyard, I never could find a consistent measurement online, and my own "tape measure" width may vary from your own...
You'll just need to run the proper offset wheels on the wider rear.
Also consider a Jeep Liberty 8.25 rear. Similar width to the XJ, plus you get disc brakes.
I believe member @Cruisingram did the swap with an XJ rear?
 
Not well versed in this subject other than Rick Eherenburg suggested this swap. On one of my junkyard crawls I dove under a bunch of grand Cherokee’s. The pinion gear shaft looks small and weak. Not sure if they were the right axles though. Probably stand up to a /6 or a stock 2 barrel v8.

Disc brakes and an aluminum center section case where its desirable points.
 
ZJ Grand Cherokees are too wide- if it looked spindly you've got to make sure you're looking at an 8 1/4 and not the Dana (35-44, don't recall which offhand) that was also used. If it had an aluminum center, it was a Dana- and yeah, I've seen a few of those get scattered behind a warmed-up smallblock... What is useable on the early (5x4.5 bc) GCs is the optional rear disc brakes, which bolt on to 8.25s without too much fuss.
Have heard differing information on the YJ (Wrangler) suitability also, so I am not sure on the viability of that rear end.
 
If they're 59.5" drum-drum then they'd basically be the same as a 65-67 B-body 8 3/4 for width, which is very doable for a Duster but your rim/tire goals will be important.

You'd need a conversion joint for the yoke and you'd need to have new perches welded on. The driveshaft length change would depend on what you've got in there now for a rear axle, I'm assuming it's a 7.25 otherwise we probably wouldn't be having this conversation.

The 8.25 should hold up great behind a /6 or mild V8, they're not quite as strong as an 8 3/4 but if you're not making big power or doing any significant drag racing it shouldn't be an issue as long as the 8.25 is in good shape.

The wheels you want to run are definitely a consideration, if you're looking at 15" wheels and want to run wide tires out back the wider rear can be a disadvantage, you need to run more backspace. I have a 68-70 B rear in my Duster, it's 60 1/8" drum to drum and with a stock 15x7" with a 4.25" backspace a 225/60/15 is the best you can fit in the wheel well. You'd have a little more room, but probably not enough to get a 235 in there on a stock 15x7. If you wanted to maximize your tire size and are going to keep the leaf springs in the stock location you'd be looking at a 15x8" with around 5.25"- 5.5" of backspace, which will put you into custom wheel territory. Of course you're welding on new perches, so, if there was ever a time to install a 1/2" spring offset now would be the time. But that just makes the backspace issue worse, since it basically means adding another 1/2" of backspace to take advantage of it.

Now, if you're looking for 17" or 18" wheels and want to maximize your tire size a 9" wheel with around 6" of backspace would do it with stock leaf spring locations and that 59.5" wide rear, and that's a fairly easy to find off the shelf wheel. So that wider rear axle is no problem if the plan is 17/18" wheels. If the plan is to stick with 15's, well, it very well might mean a custom offset wheel if you want to run any kind of wide tire back there.

Those are all just rough numbers for the backspace, you should measure your own car because they're definitely all a little different and if you really want to maximize your tire size the factory tolerances make a difference. I'm just basing those numbers on the measurements from my cars, and using the 59.5" dimension for the rear axle.
 
yup, car is a slant and I plan to keep it that way....down the road I'd like to get an aussiespeed long runner 2bbl, a cam in the [email protected] range, headers, and pick up another head to port and mill....

currently is the original 3.23 geared 7.25" rear end, factory iron case A833OD. build date is 11/75 so it has SBP drums all the way around, a disc brake conversion has been on my mind since we bought it when I was 16 back in 1991....

rims, not sure....not much selection any more in 14 & 15" tires, so I was thinking of going to 17's....if I do go 17's I'd probably look at 255/50R17's in the back and whatever I can fit up front....guessing something like a 225/45R17....maybe mustang bullitt rims (17x8, +30mm offset/5.72" BS) the 205/70R14 on the front now are about all the bigger diameter that will fit with the stock SBP backspace.
 
michiganpat said:
yup, car is a slant and I plan to keep it that way....down the road I'd like to get an aussiespeed long runner 2bbl, a cam in the [email protected] range, headers, and pick up another head to port and mill....

currently is the original 3.23 geared 7.25" rear end, factory iron case A833OD. build date is 11/75 so it has SBP drums all the way around, a disc brake conversion has been on my mind since we bought it when I was 16 back in 1991....

rims, not sure....not much selection any more in 14 & 15" tires, so I was thinking of going to 17's....if I do go 17's I'd probably look at 255/50R17's in the back and whatever I can fit up front....guessing something like a 225/45R17....maybe mustang bullitt rims (17x8, +30mm offset/5.72" BS) the 205/70R14 on the front now are about all the bigger diameter that will fit with the stock SBP backspace.
Click to expand...

The mustang bullit rims would work pretty well front and rear with the right tire sizes. A 225/45/17 is a bit on the short side though at 25". And 255's are not the best for selection in the 17" size. A 255/50/17 is basically a light truck tire, not much in the way of performance options, I think there's a Nitto and that's about it. A 245/45/17 actually works pretty well up front on a bullit wheel or one with similar specs, and that's a pretty popular size with a lot of tire choices. You could run that one front and back for a "square" set up and be able to rotate tires. The other popular size with a lot of performance options is the 275/40/17, which will fit in the back even with the stock spring locations if you get the backspace right. But that would take a 17x9", and that doesn't work well up front because the 17's don't usually clear the outer tie rod end at the 6" backspace you'd need to run them up front.
 
back in the day I ran continental 255/50R17's on my 5th ave, looks like those are discontinued now. the 205/70R14's on the front are 25.25" tall and they are pretty tight to the leading edge of the front fender when turning. especially if I go with an XJ 8.25" rear to get the BBP out back, I'll want a taller tire, something 27-28" since I'll be going from my current 3.23 to a 3.55, unless I can find a 3.07 out of a manual jeep.
 
michiganpat said:
back in the day I ran continental 255/50R17's on my 5th ave, looks like those are discontinued now. the 205/70R14's on the front are 25.25" tall and they are pretty tight to the leading edge of the front fender when turning. especially if I go with an XJ 8.25" rear to get the BBP out back, I'll want a taller tire, something 27-28" since I'll be going from my current 3.23 to a 3.55, unless I can find a 3.07 out of a manual jeep.
Click to expand...

The backspace in the front has a lot to do with that front corner clearance, a 25.25" tall tire should easily clear the front corner with decent backspace. I would wager your current 14's have very little backspace. I ran 275/35/18's on my Duster on 18x9's up front with about 6.1" of backspace, and those cleared the front corner. They're 25.6" tall. Front corner clearance is a bit of a dance between height and width too, the 275/35/18's were close to the corner more because of their width than their height.

With an OD transmission I don't think I'd worry nearly as much about that rear tire/ratio change. 3.55's with a .73:1 4th like that 833 OD should have would make freeway cruising a piece of cake even with a 25.7" tall tire. That's 70 mph at 2,400 rpm.

At any rate, you won't find much in a 27-28" tall performance street car tire for a 17" rim in a decently wide width. Really the only option is a Nitto NT555 G2, maybe an Invo depending on the size. Even the tire selection for 17" rims has dropped off quite a bit.
 
michiganpat said:
they are OEM 14x5.5 SBP rallyes

still a lot of selection in 235/55R17's for 27" tires
Click to expand...

Not if you eliminate “all-season” tires. TireRack lists 80 tires in that size but only 2 that aren’t “all season” and only 1 of those 2 has a tread wear rating under 400.

Do what you like, but IMO that’s the worst selection you’ve posted so far. The vast majority of the tires in that size are meant for crossover SUV’s or commuters.
 
it's a slant 6 duster, I'm not going to be autoxing, running it on a track or being supper aggressive driving it....I have my R/T road and track charger if I get that itch.
 
since I'm planning on keeping the slanty, and while I do want to warm that up some, I doubt I'll ever be more than around 150 RWHP/150 RWTQ (comparable to this build )



it looks like the dana 35 out of an XJ or a YJ/TJ wrangler would be another option. it's considered a "weak" axle in the jeep world so people practically give them away, and it has the slight advantage of 2.5" axle tubes, so someone replacing a 7.25" axle won't need to buy new shock plates....
 
You must log in or register to reply here.
-

Back
Top