RPM Mark

iTrader: (4)

This seems like a simple question, but for some reason I have not figured it out myself yet.

What exactly is making the klunking noise when you go from P to D or R at the time the trans engages. Is it too much play in the rear end or an output shaft problem?

This is a stock car, and if you're not sure of the noise I am talking about you've probably heard it before on any given RWD GM car that has some miles on it.

Any help is appreciated, just trying to get some opinions and see which direction to go in order to eliminate it.
Thanks
Mark
RPM

bene

iTrader: (16)

+1 on this too!

Arc00TA

iTrader: (17)

+1, this bugs the crap out of me

A-RoN'sZ

+1 for me as well...has been driving me crazy lately.

performabuilt

iTrader: (25)

This is drive train play I dont think theres anyway you could eliminate it other than reduce all clearances to 0 but that wont work either

revtime

iTrader: (1)

Check your Ujoints this is usually the problem.

usd2sing

iTrader: (15)

subscribed

FLT

iTrader: (1)

I would check the rear end and the u joints as mentioned above. There is a good chance that there could be some slop in the trans however there are many hard parts to address this complaint. If you do have your trans gone through make sure to have your builder address this issue during the overhaul. There are a couple of other vehicle related issues to address. What is your vehicle idling at, how are all of the mounts, does it do it more so when hot, and so on. As far as the trans is concerned the sun shell and reverse input drum are the two that come to mind for reverse. As far as forward the front planet reaction shaft splines to the ring gear wear. The rear planet ring gear support wears as well. Also the transmissions over all end play can contribute to this. Like I said there are many things that can contribute to this issue. Back when I worked on cars I really hated this complaint. Good luck with it. Vince

usd2sing

iTrader: (15)

question.

isnt there some sort of anti clunk device or set up within the trans itself?

sixvi6-camaro

iTrader: (9)

How about the trans mount? or torque arm mount? I recently replaced my motor mounts, torque arm mount, and trans mount but I can't say if it stopped any clunk or anything because the trans mount was broken and TA bushing was torn up and the car banged and clunked constantly. dunno if they could cause a clunk from P - D - R shifting just throwing out ideas.

FLT

iTrader: (1)

There is. However this piece wears as well. When this happens the case gets worn to. Like I said in my earlier post this topic really sucks as a technician.

performabuilt

iTrader: (25)

Its is any anoying issue when severe but dont confuse normal with excessive. You will have some clunk feel for several reasons. If you have ever for instance just turned the yoke on your rear end back and fourth till the whels moved each way. this is part of the lash for the rear and contributes. The amount of motion in the engine mounts and the trans mounts comes into play.The bushings in the rear again come into play , Each of these things represent a small amount of motion but when combined make for quite a bit of travel when you engage the trans. Poly mounts etc only serve to make this shock transfer even more into the car. GM didnt use the soft spongy and liquid filled mounts to save money it was to address this issue along with drivetrain vibrations. Other things as mentioned that can contribute is higher idle speeds such as you need with a larger cam ETC. But to actually get rid of it all together I dont think that would be possible. I have been in many new cars right off the lot and even they had some level of it. Though again GM did a pretty good job of hiding it with those soft spongy mounts everyone in the performance world likes to do away with lol

Gilbert@Ace Racing

This is an issue that has no clear cut and dry answer. It can be generalized to say that there is normal driveline slack. And it can be said to be a specific compnonent that has failed... or in high mileage hard lived cars it can be a combination of things.

My '07 Dodge Dakota has driveline slack at 16k miles... has been there since day one and has not changed. All automobile manufacturers deal with this issue and have for years.

The problem can be more evident if the car has been equipped with aftermarket suspension components, has had a rear axle swap and so on.

The key here is to have your vehicle checked out by someone who understands your car inside and out. What you are looking for is the peace of mind that there are no failed bushings, mounts or that the condition is not excessive. Too much backlash in the rear gears will cause this as an example and that can get expensive right?

Hope that helps.

g

RPM Mark

iTrader: (4)

Thanks for all the input guys. I knew that there would be more people out there that have this noise. I guess that this is just going to be chucked up to wear and tear on a number of parts. I fully understand that you cannot eliminate all the play in the rear end bc you need that for the gears to work properly. Also the trans does need it's slop as well. The only thing is that the noise is worse (more of a metallic clunk) when the car is warm, It is a 46K mile all original car. When cold it will idle around 900 RPM and I can put it in R to get out of the garage and it will not make any noise. There will be a clear shift in the body when the trans engages and the idle drops from 900 to 550
but there will be no clunk. However, when warm and idle is around 550-600, and I go from D to R or P to D/R there will be a body shift and a clunk.
So the question is this, could this have something to do with the temp of the fluid and therefore the viscosity of it. Is it somehow affecting line pressure? I would think that it would clunk like mad dropping from 900 to 550, but it doesn't when it's cold. Or is it just that as the trans and rear end warm up after driving, the heat just naturally causes things to expand and create a greater amount of clearance between components?

Thanks a lot guys.
Mark

5301113

iTrader: (18)

Same problem here

performabuilt

iTrader: (25)

Several things come into play there. As you mentioned clearances open up , Rear end lube is thicker, Mounts have a different solidity for lack of a better word cold than warm. Trans presure table are different cold than warm. Trans fluid has a different viscosity. Really and simply everything is heavily affected by temperature lubricants,rubber parts the liquids in some mounts. Probably the only thing you really could do to help significantly would be to replace all the rubber mounts and bushings in the drive train with new OEM stuff when would get you the closest to the new stock feel for this clunk.

RPM Mark

iTrader: (4)

Which mounts/bushings would you recommend? I have replaced the LCAs and the PHB with new OEM ones during a suspension overhaul a few months ago. The only ones that are not new are the trans mount, motor mounts and the torque arm mount.

How much good, if any, would a new set of u-joints do?

performabuilt

iTrader: (25)

All of those things can help.