slam noise on acceleration (1 Viewer)

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After searching around using various search terms I am still more or less at a loss at isolating the problem.

I have a few louder than usual noises coming from what I believe to be the back half of the cruiser between the T case and Rear axle. All of them concern me but the one that worries me the most is when I am driving along at posted speed and need to apply gas to maintain that speed. If I add gas too fast I get a momentary pause, then a slam feeling and noise under me, followed by acceleration under applied power. Once I ease up on the gas, I also get a feeling that the driveline releases or unwinds a little.

It feels like there is slack or play in the gears somewhere. The good news is that I am going into the Transmission and Tcase for some work to fix anoying leaks soon so I will have time to look at those components along with the drive shaft, U joints. etc. for excessive play.

I am leaning towards pinion issues. Is this classic pinion bad behavior or should I look elsewhere?

The bad news is that I am moving soon and need to drive this rig 700+ mi to its new home. So I need to prepare quickly to ID and confirm this problem, get parts and fix it when I have the Trans and Tcase out.

Thanks in advance.
 
Look at your trans mount....at least that is an easy place to start. Had a simular problem in a
Jeep and this corrected it. Also look and see if you are missing the clip(S) in your "U" joints. Might just be an easy fix. Good luck!
 
If your rear diff pinion nut is loose you need to stop driving it immediately, replace the nut, and torque to spec.

If the pinion nut backs all the way off, and the pinion jams in the diff gears, your rear axle will lock and the truck may roll while driving. I was right behind a guy that had this happen - very scary. His truck went on two wheels, did a big j-turn, and allllmost rolled - and then slammed back on two wheels.

This could also be as simple as some loose nuts or a badly worn u-joint, but it's nothing to play with - get on it!
 
A loose rear pinion nut can also cause radial play which raises havoc with u-joints. I kept blowing rear u-joints out of my old race car until we discovered the pinion nut had loosened. After it was retorqued to spec I never lost another u-joint. The point here is if you discover a loose pinion, take the u-joint apart and inspect the needle bearings. Some may be broken. You won't discover this by the ol' wiggle test until they are ground into little bits.
 
you can also get this if your diff is setup wrong... resulting in slop between gears.. with the rear driveshaft off how much can you turn the flange on the diff in each direction (with the wheels on the ground)?

I had the loose pinion nut issue when I got my truck and it made all sorts of funny noises...
 
Sure it doesn't have a lunchbox locker in it?

You could remove the rear driveline and run it 700mi in front wheel drive without any trouble. I'm sure someone might argue with this, but it will work. It might help you diagnose the problem too.
 
Sure it doesn't have a lunchbox locker in it?

You could remove the rear driveline and run it 700mi in front wheel drive without any trouble. I'm sure someone might argue with this, but it will work. It might help you diagnose the problem too.

Except for one thing. His sig line says F&R locker. Doubt you would want to run it on the street for 700 miles with a lunch box locker in the front.
 
I just pulled the rear drive shaft off the pinion. The pinion nut looks secure but there is about 30 degrees of rotation in the pinion and a very slight ammount of wobble in the flange (L tl R; Up and Down). Guess this rotation is the slack that is taken up when it "slams" under power.

What is causing this freeplay of rotation??
 
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Except for one thing. His sig line says F&R locker. Doubt you would want to run it on the street for 700 miles with a lunch box locker in the front.
Lunch box locker? what does this mean? I have a lockrite in the front and a power trax limited slip in the rear.
 
Lunch box locker? what does this mean? I have a lockrite in the front and a power trax limited slip in the rear.

It means a power trax. 30 degrees of rotation means you need to open it up, take out the locker and inspect the gears. Something's wrong. Probably broken teeth?
 
For the 30Deg I had a similar problem with my diff and a lockright (although less than 30 deg)... I think its a problem with the diff setup from when I installed my locker... ... Mine has no teeth missing but same thing ... maybe backlash or something?

As for the play U/D L/R I would blame this on the bearing ... probubly time for a new bearing and seal in the pinion... (I had to do this on my old dodge) the bearing could be fatigued due to the other diff related issues?

If you're not too familiar with diffs (Like me) there is a couple of good writeups on the forum on how to setup a diff

You will get a few funny clicks/pops with the locker regardless...
 
Thanks for the input. Need to order a rebuild kit, then ease it into the auto hobby shop on base for a day of work. Did not really want to do a third project but I should be able to knock it out if the inside is not completely jacked up.

I need this running solid because I plan on pulling a trailer with misc stuff in it for my move at the end of the month. Going from Dayton OH to Duluth MN.
 
I need this running solid because I plan on pulling a trailer with misc stuff in it for my move at the end of the month. Going from Dayton OH to Duluth MN.

Really? I wouldn't want to pull a trailer with my locker. It only takes 1-2 hours to take it out and put in some spider gears. I actually did it on the side of the road, in the dirt, with a bottle jack once.
 
Sure it doesn't have a lunchbox locker in it?

You could remove the rear driveline and run it 700mi in front wheel drive without any trouble. I'm sure someone might argue with this, but it will work. It might help you diagnose the problem too.

Except for one thing. His sig line says F&R locker. Doubt you would want to run it on the street for 700 miles with a lunch box locker in the front.

Lunch box locker? what does this mean? I have a lockrite in the front and a power trax limited slip in the rear.

The bottom line is a auto locker (lunchbox locker) is not something your going to want to drive on pavement with. I have pulled the rear driveline before for flat towing. Then just to move it into the garage I lock only one hub. Manual steering in a 68 with Lockrites front and rear. Very interesting drive. Not something I would drive in traffic with but moving around the yard it steers easier than having both hub locks. :cheers:
 
So what I am understanding is pull the locker out and rebuild the rear diff with the original spider gears. This could be an easier solution if the power trax in the rear is messed up. I have both sets of spider gears so it would be easy to do but does it matter if I happen to put the front set into the rear?
 
So what I am understanding is pull the locker out and rebuild the rear diff with the original spider gears. This could be an easier solution if the power trax in the rear is messed up. I have both sets of spider gears so it would be easy to do but does it matter if I happen to put the front set into the rear?

That's not the route I'd take but it's definitely an option.

I daily drive my truck and will be driving it 4500 km in aug to ontario with the locker in. I think that you just need to look into getting your diff setup correctly.

As for the spider gears question to my knowledge they are the same front - rear.

to double check you insured you're pinion nut was tight correct?
 
So what I am understanding is pull the locker out and rebuild the rear diff with the original spider gears. This could be an easier solution if the power trax in the rear is messed up. I have both sets of spider gears so it would be easy to do but does it matter if I happen to put the front set into the rear?

The spiders are the same. Make sure you get the spacers in the right place, outboard of the spiders where the axles spline in.

It's a super easy job and you'll thank yourself when you're on the road towing and probably later too. You can take your time to decide if you want the locker back in there and to get an overhaul kit for it if you need.
 
That's not the route I'd take but it's definitely an option.

I daily drive my truck and will be driving it 4500 km in aug to ontario with the locker in. I think that you just need to look into getting your diff setup correctly.

As for the spider gears question to my knowledge they are the same front - rear.

to double check you insured you're pinion nut was tight correct?

I pulled the drive shaft off and checked the nut. It is still pinned in place and I do not see any indication that it moved but I did not have a torque wrench with me to test it. The flange had about 30 degrees of rotation and a small wabble. I just ordered a Diff rebuild kit.

I have daily driven my rig for years with the locker in it. Once I open it up I may opt for the spider gears or keep the locker. I just hope the Ring and pinion are not buggered.
 
Opened up the differential and found this. Looks like the inside bearing is shot, Bottom has a lot of gear dust. good news is that the ring and pinion look more or less OK. I will take it out in a few days when I have time and work on it. Hopefully just a bearing replacement and rebuild. Still have not determined the cause or source of 30 degree rotation on the pinion.
 
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