Jump to content
TEAM SHELBY FORUM

Strange vibration after TSB....


Willie

Recommended Posts

The clutch feels exactly as it did before the TSB as does the shifter. The transmission was replaced. Problem solved, right? Well, yes and no. Now I have a vibration in second and third gears. Maybe it does it in first too but it revs too fast to notice. I've never had it fast enough to test fourth. Anyways, I can feel this vibration in the seat of my pants. It's very "rough" and very obvious. It starts to occur around 2800 rpms up to redline. Here's where it gets weird. I do not feel the vibration all the time. Sometimes it's smooth as silk. Anyone else experience something similar?

Link to comment
Share on other sites

did they match mark your DS to reinstall in proper position?

 

I don't know for sure. Are there match marks from the factory? If not and the dealership did not mark it, is it possible that randomly bolting the DS back in cause a vibration? I thought these things were balanced and it wouldn't matter....

 

 

runnin stock DS? wonder if they took it out, or let it hang from the center joint...

 

Yes. Would letting it hang from the center joint cause damage?

 

Also, the vibration is dependant on engine rpm, not vehicle speed. Therefore, I believe the issue lies within the engine / clutch / tranmission.

 

 

did they replace the clutch & flywheel also..pedal action should be easier...hope they bleed the system good enough..

 

Yes, flywheel, PP, disk and the complete transmission. I saw the new parts next to my old. Initially, the chatter disappeared. But this was the case for maybe 100 miles or so. It now feels the same as when the car was new. The "hissing" points are the same too.

 

Willie

Link to comment
Share on other sites

did they match mark your DS to reinstall in proper position?

 

I don't know for sure. Are there match marks from the factory? If not and the dealership did not mark it, is it possible that randomly bolting the DS back in cause a vibration? I thought these things were balanced and it wouldn't matter....

 

 

runnin stock DS? wonder if they took it out, or let it hang from the center joint...

 

Yes. Would letting it hang from the center joint cause damage?

 

 

did they replace the clutch & flywheel also..pedal action should be easier...hope they bleed the system good enough..

 

Yes, flywheel, PP, disk and the complete transmission. I saw the new parts next to my old. Initially, the chatter disappeared. But this was the case for maybe 100 miles or so. It now feels the same as when the car was new. The "hissing" points are the same too.

 

Willie

 

Willie, you and I are experiencing the same thing. My GT500 is currently waiting a new drive shaft and "yoke" that connects the DS to the tranny. I do not know exactly why or what, but I would imagine that the DS simply was not put back together in the same EXACT fashion that it was taken off.

 

Take it back to the dealership and let then know what you are experiencing. Most likely they will diagnose the DS.

 

The DS is balanced, but has to put back in the same position it came out. If it is not, then the shudder will appear. A new unit will be needed, or the current DS rebalanced. There are no factory markings on it, and one would need to mark the positions before it is removed.

 

Letting the DS hang would cause problems, but I would like to think that any experienced tech would know that as a "no-no."

 

You will still have a little chatter, and the hissing would be the same - that is normal.

 

Hope this helps..

 

- Gabe

Link to comment
Share on other sites

Oh wow guys. Thanks all. I didn't see any of these other threads and thought I was the only one with this weird problem.

 

This is very interesting and sounds like it could be the problem. I think what I'll do is remove the front mounting bolts, rotate the DS one bolt-hole, then road test. I'll keep repeating this process to see if it makes any difference. I'll post results.

 

Willie

Link to comment
Share on other sites

Oh wow guys. Thanks all. I didn't see any of these other threads and thought I was the only one with this weird problem.

 

This is very interesting and sounds like it could be the problem. I think what I'll do is remove the front mounting bolts, rotate the DS one bolt-hole, then road test. I'll keep repeating this process to see if it makes any difference. I'll post results.

 

Willie

 

I would strongly suggest that you mark the driveshaft before any disassembly. The front flange is 4 bolts, but the center coupling has 6. There are six possible combinations if you disassemble the center coupling.

Link to comment
Share on other sites

There's no reason I can think of why the dealership would have disconnected the two DSs is there? I was thinking of merely rotating the entire assembly at the front four bolts relative to the transmission. And yes, I will mark it assuming there isn't an existing mark. I have a feeling there isn't.

 

Willie

Link to comment
Share on other sites

It's the same amount of bolts (6) to disconnect the driveshaft at either the center coupling or the rear companion flange. It's half the weight if you just do the front. The hanger bearing is mounted on the front half of the shaft and has to come down either way. You might be able to see wrench marks on the six bolts that were removed, either on the center or rear coupling. If there are obvious wrench marks on the rear six bolts and not the front, then the shaft was probably removed as one unit. If there are obvious wrench marks on only the front, the shaft might have been split. I wouldn't expect that the way that the front of the driveshaft, with the four bolts, was mounted to the trans to make any difference. I doubt that rotating the shaft at that connection would change anything, but the manual does show making an index mark at that point, and the rear companion flange, before disassembly.

 

Here's the link: http://iihs.net/fsm/?dir=82&viewfile=D...0and%205.4L.pdf

 

If you go back from this link, you will find more of the manual.

Link to comment
Share on other sites

I read the link and I believe it puts me back to square one. It basically says what I said already, that driveline vibration is dependent on vehicle speed. Mine is not, it's dependent on engine rpm. Now, as before, I'm thinking it's something internal to the transmission.

 

Willie

Link to comment
Share on other sites

I read the link and I believe it puts me back to square one. It basically says what I said already, that driveline vibration is dependent on vehicle speed. Mine is not, it's dependent on engine rpm. Now, as before, I'm thinking it's something internal to the transmission.

 

Willie

I'm thinking you may need to cut the exhaust hangers off that basically bolt the x-pipe pipe to the tranny. Many vibration issues can be cured by this. This would also be a reason that it's RPM related and not vehicle speed. The exhaust pulses send the vibration right through the tranny. Go ahead and check it out.

 

DS

Link to comment
Share on other sites

I read the link and I believe it puts me back to square one. It basically says what I said already, that driveline vibration is dependent on vehicle speed. Mine is not, it's dependent on engine rpm. Now, as before, I'm thinking it's something internal to the transmission.

 

Willie

 

Good point... That was my first reaction (tranny). If that is the case then looks like they are tearing into out transmissions again! This is kind of where my expertise stops. Hopefully the new DS will solve the problem. If it doesn't... let them work on the tranny; maybe it is a combination of the two. Either way, we will be able to pass this wisdom on to future members that have this problem.

 

I'm thinking you may need to cut the exhaust hangers off that basically bolt the x-pipe pipe to the tranny. Many vibration issues can be cured by this. This would also be a reason that it's RPM related and not vehicle speed. The exhaust pulses send the vibration right through the tranny. Go ahead and check it out.

 

DS

 

DardShadow - in mine (probably Willie too?) the vibration is WAY to hard to be exhaust related. Interesting idea.

Link to comment
Share on other sites

Good point... That was my first reaction (tranny). If that is the case then looks like they are tearing into out transmissions again! This is kind of where my expertise stops. Hopefully the new DS will solve the problem. If it doesn't... let them work on the tranny; maybe it is a combination of the two. Either way, we will be able to pass this wisdom on to future members that have this problem.

 

 

 

DardShadow - in mine (probably Willie too?) the vibration is WAY to hard to be exhaust related. Interesting idea.

Welp, you should probably do it anyway. Just one more thing to rule out. Besides, one vibration could be feeding off the other. I could be totally off base here but just cu the hangers off and see what happens. It can't hurt. I believe there was some kind of bulletin put out on it at some point as a cause/cure for NVH issues.

Link to comment
Share on other sites

Dark Shadow, An excellent thought....

 

SicShelby, are you experiencing a very obvious vibration at certain rpms too? I get a very good butt massage every time mine does this. You?

 

Willie

Link to comment
Share on other sites

Dark Shadow, An excellent thought....

 

SicShelby, are you experiencing a very obvious vibration at certain rpms too? I get a very good butt massage every time mine does this. You?

 

Willie

 

OH yeah, very obvious. It just does that in first gear though, and there are vibrations in different gears but not the same type. Hence, I have a gremlin. I'm going to find the 'lil bugger too and hang him by his balls.

 

It is very strange, and like I say, I go back and forth between DS and tranny issues, but I honestly have no way of knowing. My plan of attack is to let them screw with the DS and if that's not it... frustratingly move on to the tranny.

Link to comment
Share on other sites

You wouldn't think that it could cause as much of a vibe as it does. But, once the harmonic from the pipes get going, that transfers to the tranny. The tranny is a lot heavier and once that starts to vibrate it's gonna feel like the rotational mass of that heavy stock driveshaft. It can be very misleading. I believe I have the same issue. I just haven't cut the exhaust mounts yet. I have an alum shaft waiting to go in shortly. I'm gonna run that first then cut the mounts if needed. It's all a process of elimination.

Link to comment
Share on other sites

You wouldn't think that it could cause as much of a vibe as it does. But, once the harmonic from the pipes get going, that transfers to the tranny. The tranny is a lot heavier and once that starts to vibrate it's gonna feel like the rotational mass of that heavy stock driveshaft. It can be very misleading. I believe I have the same issue. I just haven't cut the exhaust mounts yet. I have an alum shaft waiting to go in shortly. I'm gonna run that first then cut the mounts if needed. It's all a process of elimination.

 

Ahhh the rule of thumb for da mechanic, just start ruling stuff out - you got it! That is a very interesting idea, DarkShadow, and something that I never would have considered and/or thought of. :headscratch: Let us know when your DS goes in and if it fixes anything. Sounds like we are all going down the same path - it is just a matter of who gets there first... :headspin:

Link to comment
Share on other sites

The exhaust pipes are mounted in rubber isolators that are mounted to the trans cross member. The trans is also mounted with a rubber mount between it and the cross member. I'd be surprised if any significant exhaust vibration could make it thru two rubber mounts and be transferred to the transmission.

 

Here's a link to the diagram: http://iihs.net/fsm/?dir=310&viewfile=....6L,%205.4L.pdf

Link to comment
Share on other sites

The exhaust pipes are mounted in rubber isolators that are mounted to the trans cross member. The trans is also mounted with a rubber mount between it and the cross member. I'd be surprised if any significant exhaust vibration could make it thru two rubber mounts and be transferred to the transmission.

 

Here's a link to the diagram: http://iihs.net/fsm/?dir=310&viewfile=....6L,%205.4L.pdf

I see your point but dealers have been cutting these mounts off for a reason. They have been shown to be a source of vibration. I just threw it out there for imformational purposes. After that it's your call.

 

DS

Link to comment
Share on other sites

I see your point but dealers have been cutting these mounts off for a reason. They have been shown to be a source of vibration. I just threw it out there for informational purposes. After that it's your call.

 

DS

 

DS, just wanted to let you know that I am definitely *not* shrugging off your response - I truly think that it is a very interesting point, and not one that I would have found on my own! That is what is so valuable about these forums - you get so many ideas.

 

However, since my car is currently in the shop and they are already ordered a new DS and flange, I am going to let them do that and see if it fixes the issue. If it does not, then I will have to move on. I may consider cutting these hangers either way, but if they are not giving me any issues I will leave them on there.

 

Good stuff!! :happy feet:

 

- Gabe

Link to comment
Share on other sites

DS, just wanted to let you know that I am definitely *not* shrugging off your response - I truly think that it is a very interesting point, and not one that I would have found on my own! That is what is so valuable about these forums - you get so many ideas.

 

However, since my car is currently in the shop and they are already ordered a new DS and flange, I am going to let them do that and see if it fixes the issue. If it does not, then I will have to move on. I may consider cutting these hangers either way, but if they are not giving me any issues I will leave them on there.

 

Good stuff!! :happy feet:

 

- Gabe

Of course, no sense in cutting them if you don't need to. That's why I'm waiting to install my alum before doing it myself. Like I said, just something to consider. It doesn't do anyone any good keeping it to myself. Good luck finding your gremlin. I have one of my own to chase now. I have some kind of exhaust rattle after installing Bassani Race Axle Backs. Strange thing is...everything is tight and nothing is making contact with anything it shouldn't be. I just keep telling myself.."I love my car, I love my car, I love my car". :hysterical:

Link to comment
Share on other sites

DS, I recently installed a DynoTech alum driveshaft and I'm happy with it. I haven't track tested it yet.

 

Sic, Could it be the rear companion flange, that mounts to the front of the differential at the pinion shaft, that your dealer has on order? If there was excessive runout at that flange, it might cause driveshaft vibration. I think the allowable runout is .005". I'd have to look it up to be sure.

Link to comment
Share on other sites

DS, I recently installed a DynoTech alum driveshaft and I'm happy with it. I haven't track tested it yet.

 

Sic, Could it be the rear companion flange, that mounts to the front of the differential at the pinion shaft, that your dealer has on order? If there was excessive runout at that flange, it might cause driveshaft vibration. I think the allowable runout is .005". I'd have to look it up to be sure.

 

I am chasing you across the forum, ha-ha. My thinking is Rob (the tranny guy) is ordering the whole kit and kaboodle to be sure - the DS and the flanges. The DS is at the dealership, and the yoke is what is on "backorder until late next month." :banghead: I think they are referring to that flange, maybe even both (to the tranny and the dif).

Link to comment
Share on other sites

I am chasing you across the forum, ha-ha. My thinking is Rob (the tranny guy) is ordering the whole kit and kaboodle to be sure - the DS and the flanges. The DS is at the dealership, and the yoke is what is on "backorder until late next month." :banghead: I think they are referring to that flange, maybe even both (to the tranny and the dif).

 

Ok, well here's the next consideration if he's replacing the companion flange. The nut holding the companion flange on also tighens and compresses the crush collar. The crush collar sets the preload for the pinion bearings. I wonder how the mechanic is going to reset the pinion bearing preload if he removes the companion flange and nut? Will he install a new crush collar?

 

Here's the link for the procedure: http://iihs.net/fsm/?dir=93&viewfile=D...nion%20Seal.pdf

Link to comment
Share on other sites

Boy oh boy, I wish I knew!! :shrug:

 

I feel so in the dark. All I can do, I feel, is leave this up to the dealership and hope they know what they are doing. That is really the only option I have at this point. If I start butting in I risk setting off the guys who are working on it, and the last thing I want to do is make them feel like I am stepping on their toes.

 

I really do not know.

 

Anybody seen Willie? Hopefully he is figuring his out.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...
...