D30 problems and questions

[Quacked]

I just finished replacing parts in my D30 dif due to blowing the spiders which of course had to knock a big hole in the ring and pinion.

I found a "low milage" used front for $150. I bought the assembly with the intent on trussing the housing, adding jonny joint brackets and welding on the new brackets for a ROR Hi-Steer kit, then getting the housing completely tore down, sandblasted and powder coated before I put the much needed 4.55's in it. I was going to do my spare 35 the same way at the same time.

Well the low milage front upon tear down had a fair gear set and spiders, but the bearings were way brindled, almost blue. So I had to spend more money, and order a superior overhaul kit.

When I bought this XJ, it had 100,000 miles on it, but had been ditched hard enough to tear off the exhaust. The truck has always had a vibration in the front (almost a harmonic) that would start shaking the keys at 65 mph. This was before it was lifted, and still my wifes driver. In trying to defeat the vibe I had rims checked for straightness, tires repeatedly balanced, and the front shaft out several times to check for straightness and balance. Nothing fixed it. So I started to speculate that maybe it was play in one of the pinion bearings or maybe output shaft bearing in the xfercase?

So I was excited to see if the vibe was gone.

Unfortuneatly, it seems worse, and now my keys are shaking at 50 with my well balanced BFG all terrains and new winter wheels.

Front shaft removed, and there is no vibe.

So it was obviously not the pinion bearings, so I am going to hypothesize what it may be and see if anyone agrees.

What are the chances the vibration are from a slightly bent housing and is being caused by the axles moving in the dif. carrier off plane?

The only other cause I can think of would be the output shaft support bearings.

What else do you guys think it could be?
......................................................................................................

Now here is my other question.

I was suprised by how tiny the axles and ring gear were on the D30, and am starting to question spending any money on the D30/35.

My truck with 33's does spend most of its time on road, and pulling a big duck boat tandem axle 20 footer, and a 16 foot fishing boat is required.

I want to have extreme reliabilty, but dont need to ge real big like 60's. If I truss the 30/35's, will I just keep breaking dif's?

I am loathe to go to 44's because I have a sweet set of wheels, but will have to if I must.

SO if you were needing to use your truck like I do would you do the 30/35 with superior super kits, or go with stock 44,s from a full size Cherokee?

Thanks,

Brad

 

[NighthawkXJ]

Find a 44 for the rear out of a late 80s xj, and it will bolt right in, and you can keep your wheels, as for the dana 30, there are alot of guys around here running 35s on a offroad only rig, and they just upgraded to chromolly axle shafts and have not had any more problems.

For your rear, a 8.25 is also a pretty good axle, there is no cut off for carrier changes on gears, so you could just buy it, drop some gears in it, and be ready to go. It would outlast your d35 by a long ways. Just try to get the 96+ 8.25 so you can have 29 spline.

 

[Quacked]

Sweet with the 44 rear, that should save enough money for an ARB in the front!


What do you think about the vibration then?

 

[NighthawkXJ]

have you checked all your ujoints?

 

[Quacked]

Yes, actually I replaced them all 4 weeks ago before i blew my dif. Also changed the joints on the axles.

 

[non-stick]

Have you checked the front DS balance? If you are running a non-disco front end you are driving the front shaft, the vibe could come from there.

HTH

 

[Quacked]

Yes I had the shaft rebalanced twice by two different shops as the first time did not fix it.

THe shaft is also straight.

 

[98stocker]

Since you say the vibe is gone with the front shaft out, and you say the shaft has been balanced twice and is good, I would say either your pinion angle is wrong causing the vibe, or the front output bearing in the transfer case is sloppy allowing the vibe or the pinion bearings are sloppy.

 

[Quacked]

Pinion bearings are new superior bearings.

I think it must be the output, because if the axles were sawing there would be MUCH heat, and silver lube. The old shaft and carrier would also show excessive wear on the splines.

 

[NighthawkXJ]

take your driveshaft out and grab the yoke on the front of the transfer case, if you can move it up and down, or left and right, i would say you have found your problem.

 

[Quacked]

Ok, but then what do I do for the rest of the day? And with all the beer I bought?

 

[cal]

It sounds like the slip joint in the front driveshaft is worn out, allowing it a little play. It's very common on XJ front shafts. You can pull another front shaft from a junkyard and try it, or spend the two hundred and have a new shaft made - which is probably the better option.

Some of our local guys run with no front shaft most of the time, and take 5 minutes to bolt it in at the trailhead, remove it before heading home.

-C

 

[Quacked]

You hit the nail on the head.

I grabbed and wiggled and big play on the slip joint.

I will get one ordered tomorrow.

I also looked and not only does my POS Rough Cough country lift have the springs hitting the bump stops going boing all the time, but the driveshaft only has 1/2 inch of clearance left in compression on the slip joint.

 

[cal]

Those are both pretty normal. If you look at it, your slip joint does not move very much. As the axle goes "up", it also goes "forward", so the slipjoint doesnt really do very much (although, is critical.. )