[csands]

Any ideas what is causing the front and rear drive shaft to clunk at engine start up, if i start the engine in neutral it will not clunk and it also doesn't happen all of the time.
Just replaced all fluids in TC / Front Diff / Rear Diff / Transmission
I was getting the clunk before changing the fluids.

 

[wesyder]

I have no idea, mine does this too for as long as i can remember, it's definitely coming from the transmission

 

[the cadillac man]

Mine has done this a few times and I think it due to the park pawl being in a bind
I fixed the park brakes and use them ever time I park the truck and no clunk noise

It would be real back when parking on a hill(plus would be hard to shift out of park)

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I could be wrong though

 

[godsdiablo]

No Cadillac man don't use the ebrake ! I used to use mine my driveway is also a hill and from over time it cut a wire in there leading to my driver side door speaker. Morons at GM thought it would be a good idea to run the cables BEHIND the ebrake not infront of it strapped up so when you keep pressing it down it stretches and stretches until one breaks.


Also mine did this a few times if I really got on it the last time I drove it

 

[Skier-24]

Any ideas what is causing the front and rear drive shaft to clunk at engine start up, if i start the engine in neutral it will not clunk and it also doesn't happen all of the time.
Just replaced all fluids in TC / Front Diff / Rear Diff / Transmission
I was getting the clunk before changing the fluids.

Check your motor mounts?

 

[the cadillac man]

No Cadillac man don't use the ebrake ! I used to use mine my driveway is also a hill and from over time it cut a wire in there leading to my driver side door speaker. Morons at GM thought it would be a good idea to run the cables BEHIND the ebrake not infront of it strapped up so when you keep pressing it down it stretches and stretches until one breaks. Also mine did this a few times if I really got on it the last time I drove it

Good to know I will check that and re route the wiring as I would hate to kill my driver's door speaker connection(which would knock out both door speaker and tweeter with my aftermarket speakers)
Though mine doesn't go down far since I had the park brakes properly adjusted so they hold without needing to push the pedal to the floor

I just hate to put stress on the park pawl as it would really cost to repair

 

[wesyder]

I use the parking brake, i also notice and rerouted those wires long ago, motor mounts are fine, it happens very sporadic, flat ground, up hill, down hill,

 

[godsdiablo]

Where did you reroute them? I tried to move mine around it wasn't long enough

 

[Z71]

This is a common phenomenon with these year GM trucks and SUV's. My 2003 GMC pickup did this. It does no harm.

INFORMATION Bulletin No.: 08-07-30-026

Date: May 22, 2008

Subject:
Information on Slight Vehicle Movement In Park At Start Up After Cold Soak Models:
2009 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn)
2009 and Prior HUMMER H2, H3
2009 and Prior Saab 9-7X with Automatic Transmission

Some vehicles may rock or move slightly forward or rearward while in park at start up after cold soak. This condition may be accompanied by a clunk noise. This is a slight movement that is more often seen visually, rather than felt, when viewed from the outside and using the auto-start feature, if equipped.

This slight movement is due to the residual transmission fluid in the clutch packs that creates a partial apply on start up. This movement is stopped by the parking pawl and/or transmission fluid exhausting completely from the clutch packs.

This slight movement has no adverse affects on the transmission and no repair should be attempted. This condition is normal. This can be verified by comparing with another identically built vehicle under the same cold conditions.

To prevent this condition from occurring, the parking brake should be utilized as per the Owners Manual recommendations anytime the vehicle is parked.

 

[csands]

Reading the above TSB i use the parking brake and it still does it but not quite as bad.
On another note if i shift the transmission into neutral and start the vehicle it doesn't happen, any other ideas anyone?
Also replaced slip yoke and u-joint with updated parts.

 

[jimmy88]

I park on a grade and i noticed that if stop the truck shift to nuetral then apply parking brake ,let off brake pedal then shift into park, it doesn't do it. Before i realized that the parking brake was a science it would happen almost regularly.

Funny thing is i always used the e brake,just not that well i guess.

 

[csands]

Thanks I will give it a try and I will post the outcome

 

[the cadillac man]

I do like jimmy88 and haven't had a issue so far
Strange

 

[csands]

Tried what jimmy88 and the cadillac man said and got no change.
Still trying to figure this one out.
Noticed that you can completely turn rear drive around when in park and vehicle on a hoist, is this normal?

 

[the cadillac man]

Tried what jimmy88 and the cadillac man said and got no change. Still trying to figure this one out. Noticed that you can completely turn rear drive around when in park and vehicle on a hoist, is this normal?

That's normal as its due to the weight of the truck not on it and the tranny in park

 

[csands]

Ok thank you


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[csands]

Any one know where I might a good deal on a reman transfer case


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[the cadillac man]

Any one know where I might a good deal on a reman transfer case Sent from AutoGuide.com Free App

Rock auto

 

[csands]

Since my last post i discovered that if i let the truck roll after putting in park i don't get the described clunk at engine start-up, but if i use the e-brake before shifting into park it will clunk.
Sounds like the parking pawl is not fully engaging.
Do you think it is possible that the shift cable might need to be adjusted?

 

[the cadillac man]

Since my last post i discovered that if i let the truck roll after putting in park i don't get the described clunk at engine start-up, but if i use the e-brake before shifting into park it will clunk. Sounds like the parking pawl is not fully engaging. Do you think it is possible that the shift cable might need to be adjusted?

I would say so
Though putting stress on the park pawl is not good for it