Driveshaft bolt pattern doesn't match (1 Viewer)

[cliffrdavis]

I'm going forward with my suspension replacement on my 81 40 and I've got a small problem. Front driveshaft was not on the vehicle when I purchased it, but previous owner gave me one he claimed was for the 40.

I've moved the front axle back (supported by a jack) while the springs were off. The drive shaft bolted up to the transfer case side without a problem. However, the front driveshaft bolt pattern is slightly larger vs the front axel bolt pattern (58 x 63mm). Measurements are center bolt to center bolt in a rectangle, not an "X". I'm assuming I have the wrong year driveshaft/yoke flange, but it could also be the wrong axle! Looked at pics and my axle looks stock for an 81??

I've attached pics of the axel and the yolk/driveshaft hookup.

Does someone know these details or can someone measure their bolt pattern on the front driveshaft axle side. Thanks in advance!!

CD

 

[reddingcruiser]

You need to scrounge up a the correct late model flange. Pull it out so you can find out to see if it's fine or coarse spline. Can't see enough from the pics to tell if it's a drum/disk conversion or OEM Disk.

 

[cliffrdavis]

Measured the driveshaft bolt pattern and it was 2.3 x 2.5in. Wondering which is the wrong year, driveshaft or axle?

 

[Tigerstripe40]

An 81 should have 3.73's in the diffs. I suspect that someone may have swapped in some diff's from an earlier truck to get the 4.11's. The input flange on the diff looks like one of the earlier '3 speed' flanges which is smaller. If the diff is what I think it is, you will likely need one of the flanges from a 75-77 diff as those are corse spline but should match the driveshaft.

 

[cliffrdavis]

Can I remove the flange on the differential without disassembling the entire thing? I was under the impression the cover had to be removed and oil drained to take off the flange. I'm assuming your are saying I can remove the center bolt, bang off the flange and look at the spline type, which should tell me if it is an older/newer model? Even if I know what year the diff is, I still won't know which is correct, the diff flange or the driveshaft/yolk flange.

 

[cliffrdavis]

pic with measurements

MS Paint to help. Wish my familiarity with diffs from fj40s was as good as my knowledge of other crap!

SOR recommend a drillable universal flange. Any thoughts?

 

[Poser]

Any thoughts?

Yes:


No need for a “drillable flange”.


As was previously suggested, remove the current flange and find out if it is coarse or fine spline.

(post up a picture of the flange splines and someone will help you with this)

Then, post up in the wanted section with what you have and what you are looking for.

Someone will have one.

 

[DacotasFJ40]

Try Cruiser Outfitters.

Try cruiser outfitters. They have what you are looking for. Earlier model course splines with late model drive shaft bolt paterns.


click on Link
Cruiser Outfitters

 

[cliffrdavis]

Great, thx. Have a manual but it doesn't tell me how to remove it. I assume lock the brakes, turn the large nut on the pinion flange. I assume I'll need a gear puller to remove the flange from the pinion?

I did the quick and dirty method to check the diff ratio, spun the tire and counted rotations of the pinion flange and it was 4.1, makes sense. I did it just to assure I had wasn't going to have a 3.7 up front and 4.1 on the back. The guy I bought it from was shady.... I mean I carried a gun on my side while paying shady!! He wasn't a mudder as you might imagine.

 

[Tigerstripe40]

I would make sure that the front and rear diff gear ratios are the same.

IF the truck is sitting on the ground, lock up the front hubs, remove the pinion nut (its torqued on to 150ft/lbs IIRC). You should be able to pull the flange off without the need for a puller.

 

[KY Longhunter]

Have you checked here yet?

Cruiser Outfitters

 

[cliffrdavis]

Thanks for the link. I actually looked at their site and their flanges but not the Tech section. Interesting since I have 8mm holes, with those measurements I would have a 63-69 flange w coarse spline. Other possibility would be a mini truck flange with fine spline (but mine is square not round). I'm going to try to get the flange off tomorrow am to check the splines.

Thanks for the help...

 

[green40]

Great, thx. Have a manual but it doesn't tell me how to remove it. I assume lock the brakes, turn the large nut on the pinion flange. I assume I'll need a gear puller to remove the flange from the pinion

The nut is staked to the pinion, free that up, remove the nut and the flange
will just slide off. No need for a puller. While it's apart you might as well
replace the seal.

 

[rockcod]

Call Kurt at Cruiser Outfitters, he sells coarse or fine spline flanges (round type as you mentioned) you can redrill to the proper bolt pattern. You will need to redrill the parking brake drum too, pound out the the studs, index it 45* and redrill. I just did this on my 40, I am running FJ60 CV driveshafts front and rear, not a big deal to do.

 

[cjgoode]

The nut is staked to the pinion, free that up, remove the nut and the flange
will just slide off. No need for a puller. While it's apart you might as well
replace the seal.

No need for a puller, but an impact wrench is a must. 2 seconds with an impact and it is done.

 

[cliffrdavis]

Got that. Anyone know the size ratchet needed? I was going to measure it with a caliper and go buy one, it looks like 30mm or more!

 

[Tackleberry]

did you get the pinion flange off?
how many splines?

 

[TLC76]

I'm about to have an extra course spline flange off my '76...

 

[cliffrdavis]

Had to leave town, got a buddy with cancer thats doing bad.... left the cruiser on jacks... wife appreciated that! Going to hit it Friday or Saturday. Interestingly, I found the thread about steering arm attachment bolt pattern, mine is the large pattern consistent with later model axel, but I've got 4.1 gears up front. My discs look like they are late model according to description of the discs on Mud. As suggested above, likely someone switched diff gears to 4.1 on my late model axel.

Haven't had time to check the rear to make sure they are the same. If rear are 3.7 it looks like I'll be doing a ring/pinion exchange..... Never done that, but you got to learn somehow! Once I get the flange off I'll drop you guys a line to see if one of your flanges will fit.

 

[cliffrdavis]

I've been slowly working on my pinion nut with PB blaster, breaker bar and torch to no avail. Was going to give it a couple more days to let it soak.

Been trying to do my homework on brakes and diffs so I would know what I'm getting into if I needed to replace the ring and pinion. During my education I saw a thread stating that FJ 55 axles have a square metal block over the springs which is not present in 40s. My axle has this block, see pics above. I've attached pics of my brakes and hubs for reference. Is this a fj55 axle? There is so little Info on 55s on Mud that I can't tell if it even matters? Would that mean this is a disc conversion?

Caliper says S12-8. Difficult to read lower letters, maybe K XE? No year tag on the brake lines as suggested on other threads.