The "Clunk": Here's what I'm going to do [new info and links from CTS boards]

[windface]

I haven't driven a Solstice yet, let alone heard the clunk. But when we do see one in my dealership with the clunk complaint here's what I am going to try. First let me say that when scubaman was having his ordeal, we swapped a couple of PM's, and I advised him his dealer should add GM additive #1052358 to the fluid. They did. It's purpose? To reduce friction in the LSD clutch plates, thus reducing noise. Unless GM comes up with a definite cause, I'm draining the fluid, and putting in the additive. It may work, and it may not, but the thinking here is since the majority of car's with the clunk have LSD it is going to be worth a try. By the way the additive only goes in if the car is LSD equipped. Also it's standard procedure to add it to any LSD rear end, once the fluid is changed. If by some miracle this would be the problem, then some car's were shipped without the additive from the factory, and thus explaining why some car's are not experiencing the clunk, and some are.

[solkool]

I don't have the LSD so whadda ya think is going on???

[windface]

Originally Posted by solkool I don't have the LSD so whadda ya think is going on???

Truthfully solkool, I don't know. I take it your's clunks, and yet the poll shows a large majority of car's doing this have the LSD option. Maybe that's because most car's delivered so far have LSD. I wished I could hear it for myself, but our dealer hasen't even gotten a Solstice yet. Since sound tends to travel through the car, it can be real hard to exactly pin point the origin of the noise. We have a special tool for sound isolation, and I have used it with some success. That will be utilized on this problem too if I ever have to deal with it. The additive I mention is GM required when refilling LSD rear ends, to minimize noise. So as simple as it is to add, I feel it's worth a shot. Sometimes it takes a little experimenting to solve a mystery.

[Josh]

I havent noticed the "clunks" now with 300+ miles on my Solstice. Personally? I think it's because I've gotten comfortable with the transmission enough to pin point the shifts, etc.

[Solitud]

We only hear the clunk when the RPM's are low. If we raise the rpm's before shifting we don't hear any clunk and the shifting is much smoother. It is also only between 1st & 2nd gear (sometimes going into 3rd but rarely).

Just my $.02

[bradyb]

Describe the sound guys, I've never heard it.
Some questions/ideas..
Does it sound like something shifting, like weight transfer through the suspension?
Is it a drive line noise like the push/pull of a UV joint?
Is it in the tranny?
Is it the exhaust tapping againts something with low RPMS when you let the clutch out?
Is it at different RPMs?

[Dasto]

Mine is more than a clunk. Accelerate a little in first gear and then depress the clutch and hold it in and listen. You will get a distinct shudder or rattle. Kind of make a noise like metal rods vibrating. Kind of a shudder noise. I also have the clunk that everyone is talking about. I have owned many 2 seater, 4 cyl, 5 speed roadsters with LDS...have 3 right now. Never had anything like this at all.

[Chip]

windface; That looks like a good plan! LSD's in my view require a bit more care than do standard diffs. What is the recommended change interval for the diff. lube? S2000 owners also need to change out their lube pretty frequently. Not to take your thread off topic but, can you get any info. on the relief valve on the diff. I am curious about it's unseating pressure.

[tweety]

Not really getting how the LSD's are having a clunk. Mine doesn't do it at all.
Most of the time I start off like others and must miss it completely yet on the days where I am in stop/go traffic, I still don't hear or feel anything.
This isn't for all machines I guess.

[bradyb]

I don't think its a LSD issue, if that were the case it would do it when you were going around a corner or if one wheel was slipping.

My Camaro has a clunk too. If I wait to shift and the car is coasting and then I if put in gear and let the clutch out the drive line will clunk. In my car it's just something somewhere that has a bit of play so it makes a noise when it goes from pushing to pulling. It's usually around 30 miles an hour when I'm going down hill and shift slowly

Where is the noise coming from?

[Solstice62]

Originally Posted by Dasto Mine is more than a clunk. Accelerate a little in first gear and then depress the clutch and hold it in and listen. You will get a distinct shudder or rattle. Kind of make a noise like metal rods vibrating. Kind of a shudder noise. I also have the clunk that everyone is talking about. I have owned many 2 seater, 4 cyl, 5 speed roadsters with LDS...have 3 right now. Never had anything like this at all.

Dasto, You have described the 'clunking' very well. I’m going to ask my dealer about the additive that Windface described.....

[SgtMilburn]

I'm with BradyB. It sounds to me like some play in the drive line. I too notice it when going from 1st to 2nd and sometimes to 3rd, but only when driving like a normal human being. When I'm letting her have her fun, I never even notice/feel it. It is something that you feel also. As I put more miles and get more comfortable with Helia, I'm not hearing it as much. I guess it may be something you learn to either live with or maybe more on target, learn how to shift without "making" it make the clunk. I hope I've made some sense. Today ends 30 days of ownership with about 1280 on the old odometer.

[Lagonia]

This is a very good description and I second that. In addition to that, as someone else posted, if the RPMs are high, there is no noise whatsoever.
This is on my Sol with almost 650 miles.

All noise goes away, BTW, as I turn up my Monsoon radio to some cool XM station. So much so that I forget to shift!!!!

Originally Posted by Dasto Mine is more than a clunk. Accelerate a little in first gear and then depress the clutch and hold it in and listen. You will get a distinct shudder or rattle. Kind of make a noise like metal rods vibrating. Kind of a shudder noise. I also have the clunk that everyone is talking about. I have owned many 2 seater, 4 cyl, 5 speed roadsters with LDS...have 3 right now. Never had anything like this at all.

[windface]

STOP!!!!!!!!!!!!!!!!!!!!!!!! Guy's this morning when I got to work, a dark blue (deep?) Solstice was sitting in front of the dealership. Our first one. I drove it and clearly heard the "clunk". As you know until now I have never driven a Solstice to hear this concern, and up until now could only speculate on it's cause. Times have changed. First let me compliment the car. This roadster looks, and drives just like it should. What a great car. Surely owner's have every right to beam with pride with this car sitting in their garage. Now to the "clunk". What I heard is not a noise in the rear end at all. So scratch the additive idea. This noise is in the transmission, and I am now (as I was originally) in agreement with GM that it is normal lash in the gear's (per the SI bulletin). I don't feel that it should be heard to the extent it is however, and perhaps in the future the General can get tolerences tightened up in the tranny to reduce the noise. The other master tech I work with, is in agreement with me on this also. So it may be a little annoying, but I wouldn't lose any sleep over a possible durability issue. I also heard a noise exactly like Dasto described, so that may be an inherent sound also, and probably nothing to fret over. Guy's, I hope my input has helped out some. I wouldn't be afraid to hop in that Solstice right now and head to California, Highway 1. In fact if the boss leaves early today........ windface.

[LatinVenom]

This is the reason I have always said is the way you drive this car, I do not have the noise, that said maybe in some cars the transmission lash is a bit more noisie than others.