OK unlikely but what if I had 3.55 d30 and 8.25 3.73 gears. Would the jeep roll? Would I know?
My jeep has a Donner axle and I was curious if a repair shop could f-up and would I know years later?

 

if both driveshafts were installed, the tcase would blow up.

 

Yeah, you would probably know that within a few feet.

 

Both gear sets "MUST MATCH"!!

 

Or have different tire sizes to compensate. LOL

My dad had a 84 K5 Blazer with a 2.73 rear & 3.08 front. He said he used it once in a muddy field. No problem.

 

it was no problem because it was a slippery surface. the tires were allowed to rotate at different speeds. the same cant be said about pavement.

 

The gear sets should match, or be very close.

I had an old dodge that had 3.23/3.21, and I know ford ran 4.10/4.11 sets.

You can also run different tires sizes to compensate, like some mud racers do.

If the difference is too big you'll lunch your t-case in short order.

 

I assumed that was obvious but I guess some folks may not have comprehended the extreme lack of traction equals no breakage.

 

for some reason I'm only thinking you'd be f***ed if you put it in 4wd right? I know the front shaft is always spinning, but the front yoke isn't engaged in 2wd

even if I'm mistaken, you can always swap in your axle and disconnect the front driveline until you can afford the regear (assuming this is a build and not a street car)


seems very unlikely that you would find 3.73 gears anyway. They only came in some XJ's with the tow package iirc. better double check before you get too far ahead of yourself

 

Hmmm, good point. I don't want to be the one to find out though. I think the best bet would be to pull the front driveshaft until such time as matching gears could be achieved.

 

I've got about 1000 miles on my 90 now with mismatched axles, both axles installed. It can be done. Just don't engage 4WD. I swapped an 8.8 into the back of the XJ w/ 4.10 gears to better match the 33s on it. I have another D30 on the weld table waiting for me to finish beefing it up and install 4.10s in it to match the rear. In the meantime I have been driving it to work.

 

I too believe you can run different ratios if not in 4wd. Thus why your fwd t case yoke can spin freely while jeep is parked with no front driveshaft.

 

So bottom line is if I've spent a few hrs in 4low on the trail I would know there's a problem if there was one correct? I have the up country package but years ago I got a 97hp d30 Donner axle after an accident. I've used 4wd plenty since then. Np242 full time should eliminate any issue but 4 low would not be happy right

 

Correct. The tcase would have exploded.