Differential lugging?

[mclarke]

I had my 2A suspension changed to parabolics, and removed the hardtop. So, now the back end sits a couple of inches higher than it used to. Now, when I’m in fourth, occasionally I start to feel a “lugging” somewhere in the drive train that slows me down, and a low pitched grinding noise that accompanies it. The shop owner that did the work told me that he thought that it might be due to the way the angle of the differential was changed when the work was done. Does this make sense to you guys? I didn’t get a good impression of the shop owner, and I’m not afraid to turn the wrench myself. Anyone ever have a similar problem? Looking for some direction… Thanks, Mike

[LaneRover]

Put a big load in the back to bring it back down and see if the lugging goes away. I would think that there is at least a small chance of it being a change in the angle. What condition were your u-joint in before you made the change? Have they been greased up in recently? If not it could be a combo of the two things.

Brent

[I Leak Oil]

It's not that the angle of the diff has changed (if it did you need a new mechanic) but the drive shaft angle changes as the springs provide some lift to the truck. So providing the shop put everything back together correctly and made sure it's tight it's most likely one of three things. The U-joints, drive shaft slip joint wear or the drive shaft angle. As Brent suggested put some weight in the back to level it back out and see what happens.
Jason T.

[mclarke]

Thanks for the advice, I will try that and report back.

[S11A]

The angle would have changed to the current angle whenever your suspension unloaded, such as when the truck went over a sharp hump in the road. If you had no signs of this previously whenever that happened, then I think something else may be the cause.

Did you/the shop change the bushings? Did he grease the driveshafts (do you do that on Series vehicles)?

Is it possible that a ridge built up where the driveshaft or other components previously used to be limited in its travel?

What shocks did you go with?

Does the noise change pitch when you go around a corner or curve?

[B. Wallace]

same problem...

I am experiencing a very similar problem with mine too. I installed the Rovers North parabolics back in November. The grinding noise I experience occurs at sudden changes in speed. To better describe this, say I'm cruising along in 4th gear ( no grinding), then take my foot off the accellerator, I get a loud grinding that will last all the way down to say 30mph. Then its stops. No braking involved here. It also does it when I shift between gears sometimes. Both of these involve slight changes in the rear end height of the truck.

I did add about 200lbs in the back one day, and it did seem to help.

I was thinking that if I were to add some shims to the rear axle to get the prop back in its "original" alignment, this might help. I have never done this, nor know where to get them or what angle to get. If this makes sense to anyone, and/or knows where to get these for a Series truck, please let me know.

[siiirhd88]

You can get pinion angle shims in different degrees from a number of sources. They fit between the perch on the axle housing and the leaf spring. Summit Racing has them listed at:

http://store.summitracing.com/egnsearch.asp?N=700+115+%2D121900&D=%2D121900

I used them on the front axle to get a compomise between the pinion angle and caster when I fitted Range Rover axles to the V8 SIIA 109.

Bob
'96 Disco SE7
'80 SIII 109
'75 SIII 88 V8
'68 SIIA 109 V8
'6? SIIA 109

[yorker]

You can get pinion angle shims in different degrees from a number of sources. They fit between the perch on the axle housing and the leaf spring. Summit Racing has them listed at:

http://store.summitracing.com/egnsearch.asp?N=700+115+%2D121900&D=%2D121900

I used them on the front axle to get a compomise between the pinion angle and caster when I fitted Range Rover axles to the V8 SIIA 109.

Bob
'96 Disco SE7
'80 SIII 109
'75 SIII 88 V8
'68 SIIA 109 V8
'6? SIIA 109

Got pics of that axle set-up? how did you clear the leaf springs?