Need help ID'ing clunk in driveline

[Detlef]

Just got back from the dealer and the Viper Tech couldn't find anything wrong. It's a 2001 GTS.

These are the symptoms:

1. From a stop, put car in gear, apply some gas and I hear a creak/clunk sound coming from the rear of the car
2. Happens forwards or reverse
3. Can also hear it upon decceleration at times
4. This sound has been there for several months

Recent changes (in the last year):

• The Viper Tech put new Unitrax 800HP halfshafts on
• I have Dave's Big Brake kit installed as well
• New front stock shocks

Other mods I have on the driveline:

• 3.73:1 gears (came with the car)

Anyone have any advice on what/where to look for the location of the clunk?

 

[mjorgensen Woodhouse]

I would check the U joints on the half shafts, or the ball joints in the rear since they probably had them apart when doing the shafts.

 

[Tom Sessions]

Dry ball joints will give a creak but would also look at the dear diff mounting bolts. Make sure they are torqued to specs. The ones on the upper rails are kinda hard to get to but have seen these cause lots of noises.

 

[Detlef]

Thanks Mark and Tom.

 

[darkostoj]

guarantee its the rear driveshaft ujoint

 

[ViperGeorge]

+1 on driveshaft U joints.

 

[Asp Man]

Check you hub nuts, they've been know to come loose.

 

[dave6666]

I would check the U joints on the half shafts, or the ball joints in the rear since they probably had them apart when doing the shafts.

Having put new joints in my halfshafts, why the reference to undoing the ball joints for said work? Pulled the shock assembly, and the halfshafts fall right out. Did not touch the ball joints. Or does that vary from car to car, and I'm one of the lucky ones?

 

[All Blue ACR]

Check you hub nuts, they've been know to come loose.

And the diff housing to frame mount bolts. Had what sounds like similar noise and cgonzo after hub nuts and these tightened.

 

[Phun70]

Make sure driveshaft nut is tight at the wheel end.

 

[AndyMac]

I've got a 95 RT/10, and I tried many things like the transmission crossmember shims, tightening the rear diff mounting bolts, tightening the tranny mount, but none of the above cured the problem.

It wasn't until I read this post that it hit me. We have had several Subarus with the same problem, and sure enough, it went away by tightening the axle nut.

So, last night I took the center cap off the rear wheels and snugged them up. The L/R was right on, but the R/R took about a 1/4 of a turn. Sure enough, clunk free today!

Thanks guys!

__________________
Andrew MacPherson
My turbo projects
1995 RT/10
1990 300zx ttv8
2002 WRX

 

[Detlef]

Problem has been solved!

It wasn't the driveshaft u-joints.

After tightening the hub nuts the clunk went away.

So thanks for all the suggestions.

 

[Tom F&L GoR]

Aren't the hub nuts covered with a cage and cotter pin? After lotsa lotsa daily driver miles I realized I have the creaky noises also (thought it was me) but these axle stub shafts can't loosen. I think.

 

[Detlef]

Yes they are. It took an impact wrench to tighten enough. No wonder I couldn't do it by hand.

 

[dave6666]

Aren't the hub nuts covered with a cage and cotter pin? After lotsa lotsa daily driver miles I realized I have the creaky noises also (thought it was me) but these axle stub shafts can't loosen. I think.

C'mon Tom. The cage/pin prevents gross mechanical joint stress loss, but not micro fretting of the stress surfaces.

Yes they are. It took an impact wrench to tighten enough. No wonder I couldn't do it by hand.

I would never tighten a fastener like that with a torque figure like that with an impact wrench. Or at least without confirming said action with a torque wrench.

 

[eucharistos]

I would never tighten a fastener like that with a torque figure like that with an impact wrench. Or at least without confirming said action with a torque wrench.

serious question:

i don't have a tq wrench that goes that high (200 ft/lbs i think)

i know my weight and how long the wrench handle is, can't i just put my weight on the wrench + or -

 

[dave6666]

Your best bet is to buy the correct torque wrench. Or rent or borrow it.

Impact wrenches are likely to be way off of advertised torque. Do not rely on stated value.

Your weight on a lever is probably more accurate if you can do the logistics.

 

[eucharistos]

.... if you can do the logistics.

You must be registered for see images attach

limber like a gymnast when i need to be



always nice to check shade tree tactics

thanks

 

[Asp Man]

Problem has been solved!

It wasn't the driveshaft u-joints.

After tightening the hub nuts the clunk went away.

So thanks for all the suggestions.

Glad to have helped. (I do love it when I'm right, it doesn't happen often enough!)