Strange vibration in 3rd gear

[keith89]

Ok I did a bit of searching and haven't found anything this specific.
I'm having a pretty violent vibration in 3rd gear only under deceleration from high rpm. I've tried high rpm deceleration in 2nd and 4th with no issues. Acceleration is smooth all the way up through 4th gear as well as while coasting out of gear. I think I can rule out the IRS diff, wheel balancing and driveshaft. as they are all directly linked to vehicle speed which doesn't seem to matter.
I'm thinking it may be transmission related because it is only at high rpm deceleration in 3rd gear. It's a T56 with 26 spline input and upgraded tob sleeve.

Just to be sure, i will be double checking my driveline angles. I do have the complete full tilt boogie racing IRS bushing kit.
Any other suggestions?

 

[cotchnobra]

when did the vibration start. did it start after the FTBR kit was put in or after the trans was put in? check the U-Joints the slip yoke and also if the drive shaft has been removed recently unbolt it and turn it 180* a lot of vibe problems can be solved by this even though it is only in one gear and at a certain RPM. that could just be the sweet spot for the vibe to start happening.

 

[mu22stang]

Ever since I installed my MGW Orange shifter, 3rd gear and only 3rd has a slight off throttle vibration. Pushing forward on the shifter (very lightly) is enough to stops it. I've read that some transmissions had similar vibration in 3rd with a stock shifter. Wish I could help on a solution, but the vibration is so slight, I haven't done a thing. This may not be your issue, but try pushing forward on the shifter to see...

 

[keith89]

when did the vibration start. did it start after the FTBR kit was put in or after the trans was put in? check the U-Joints the slip yoke and also if the drive shaft has been removed recently unbolt it and turn it 180* a lot of vibe problems can be solved by this even though it is only in one gear and at a certain RPM. that could just be the sweet spot for the vibe to start happening.

It started after my engine rebuild. I have a cf driveshaft and did try clocking it. It didn't make a difference in the vibration.

Ever since I installed my MGW Orange shifter, 3rd gear and only 3rd has a slight off throttle vibration. Pushing forward on the shifter (very lightly) is enough to stops it. I've read that some transmissions had similar vibration in 3rd with a stock shifter. Wish I could help on a solution, but the vibration is so slight, I haven't done a thing. This may not be your issue, but try pushing forward on the shifter to see...

Hmm the vibration is pretty violent but I will try that. I do recall instances where I can't replicate the problem. I don't think i have the vibe when i downshift into 3rd and decelerate. I think it is just when i accelerate in 3rd and let off.

 

[jjscobra18]

Ever since I installed my MGW Orange shifter, 3rd gear and only 3rd has a slight off throttle vibration. Pushing forward on the shifter (very lightly) is enough to stops it. I've read that some transmissions had similar vibration in 3rd with a stock shifter. Wish I could help on a solution, but the vibration is so slight, I haven't done a thing. This may not be your issue, but try pushing forward on the shifter to see...

I have the same issue with my MGW always wondered if it was just mine.

 

[keith89]

I have the same issue with my MGW always wondered if it was just mine.

how bad is your vibration?
Do you all have the 26 spline upgrade? I'm wondering if it possibly has to do with the shimming job done on it since pushing forward in 3rd seems to do it for you.

 

[cotchnobra]

Do you still have the OEM harmonic balancer. Check to see if the rubber between the inside and outside of the balancer is starting to come out. I know its a long shot but I have seen these balancers cause some strange vibes in the drive line.

Edit: I'm thinking of Fox Bodies not Terminators. but check your balancer anyway just for shits and giggles

 

[jjscobra18]

Yes I have a 26 spline and a spec stage 3+. Its a slight vibration, nothing like yours its been about 2k miles since I installed it and no issues so I have not investigated it any further, also most every manual car Ive rode in or drove has had some kind of shifter shake from the rotating momentum of the drivetrain so i just left it alone. I dont know if I read over it or not, but do you still have the stock shifter? If so it maybe be the same issue as mu22stang and myself, but the beefer MGW may be cutting out some of the vib. The stock shifter was only in mine for a week before I swapped it and cant remember if the vib was there or not with the stocker. Is it a continuous vibration through the rpms?

 

[keith89]

Yes I have a 26 spline and a spec stage 3+. Its a slight vibration, nothing like yours its been about 2k miles since I installed it and no issues so I have not investigated it any further, also most every manual car Ive rode in or drove has had some kind of shifter shake from the rotating momentum of the drivetrain so i just left it alone. I dont know if I read over it or not, but do you still have the stock shifter? If so it maybe be the same issue as mu22stang and myself, but the beefer MGW may be cutting out some of the vib. The stock shifter was only in mine for a week before I swapped it and cant remember if the vib was there or not with the stocker. Is it a continuous vibration through the rpms?

I also have the MGW and 26 spline. The vibration is harsh enough to vibrate the whole car. I'm thinking it may be the transmission. it only does it under deceleration after I accelerate hard to 5 or 6k in 3rd gear and let off the gas. It doesn't do it in any other gear(well i don't know about 5th or 6th because that'd be too fast). It doesn't vibrate if i downshift into 3rd to put it at 5 or 6k rpm.

 

[MYSTCHRM]

I have this exact same issue. My hypothosis is the Spec Stage 2 clutch was too aggressive for my driving style. It would never slip in into gear. It was either on or off. I'm now having issues with the synchros so I'm having the tranny pulled and rebuilt. I'm hoping to find the issue soon.

 

[keith89]

I have this exact same issue. My hypothosis is the Spec Stage 2 clutch was too aggressive for my driving style. It would never slip in into gear. It was either on or off. I'm now having issues with the synchros so I'm having the tranny pulled and rebuilt. I'm hoping to find the issue soon.

not sure i see the correlation between the clutch and a vibration issue. Care to elaborate?

 

[MYSTCHRM]

The SPEC would grab so well that I had no slipping at all. Running the car up and down gears I feel like 2/3 was probably the hardest hit gears the way I drive. That constant aggressive catch, IMO, really beat those gears. What could it be? I don't know. The problem I do have - and last year I had a new set of synchros installed - is when you decelerate in 2nd but mostly 3rd gear I get a massive vibration. It's getting to the point that I think I feel it while holding the shifter under acceleration. I'm not a mechanic, but I had no issues with my tranny when I was using the stock clutch. Went 90K miles on the original clutch without any issues at all. Only reason why I changed the clutch was the TOB needed to be replaced and figured while the tranny was out, change the clutch. Now at 124K I'm replacing the clutch (that thing is toast) and going to have the tranny pulled and rebuilt. At the very least, I need the synchros replaced again from 2/3.

That's my thought on the issue I'm having. Not saying there is anything wrong with SPEC products. I believe it is more of my driving style and the aggressiveness of the clutch.

 

[keith89]

The SPEC would grab so well that I had no slipping at all. Running the car up and down gears I feel like 2/3 was probably the hardest hit gears the way I drive. That constant aggressive catch, IMO, really beat those gears. What could it be? I don't know. The problem I do have - and last year I had a new set of synchros installed - is when you decelerate in 2nd but mostly 3rd gear I get a massive vibration. It's getting to the point that I think I feel it while holding the shifter under acceleration. I'm not a mechanic, but I had no issues with my tranny when I was using the stock clutch. Went 90K miles on the original clutch without any issues at all. Only reason why I changed the clutch was the TOB needed to be replaced and figured while the tranny was out, change the clutch. Now at 124K I'm replacing the clutch (that thing is toast) and going to have the tranny pulled and rebuilt. At the very least, I need the synchros replaced again from 2/3.

That's my thought on the issue I'm having. Not saying there is anything wrong with SPEC products. I believe it is more of my driving style and the aggressiveness of the clutch.

sounds like a different issue from what we're discussing. The vibration on deceleration is strong enough that it shakes the entire car not just the shifter.

 

[MYSTCHRM]

No, we're talking the same issue. This vibration is MASSIVE and shakes the entire car when decelerating. What I added is that I'm now beginning to feel it under acceleration, although it isn't shaking the car. It has a more pronounced feeling of gears through the shifter in 3rd than any other gear while accelerating.

Anyway, I'll post up once the shop has an idea of what's going on.

 

[keith89]

No, we're talking the same issue. This vibration is MASSIVE and shakes the entire car when decelerating. What I added is that I'm now beginning to feel it under acceleration, although it isn't shaking the car. It has a more pronounced feeling of gears through the shifter in 3rd than any other gear while accelerating.

Anyway, I'll post up once the shop has an idea of what's going on.

oh sorry, i misread that part. do you have a 26spline input shaft and upgraded tob retainer sleeve?

 

[MYSTCHRM]

I still have the 10 spline input shaft. Not sure I'll ever need the 26 spline, I'm short of 500rwhp with no plans in the near future to add any hp, but I do have the upgraded tob retainer sleeve.

 

[keith89]

I still have the 10 spline input shaft. Not sure I'll ever need the 26 spline, I'm short of 500rwhp with no plans in the near future to add any hp, but I do have the upgraded tob retainer sleeve.

ok i was just seeing if maybe you had a 26 spline install because then i might start to think about install error causing the vibration. I did not do the install myself. I think i'm going to reinstall my stock driveshaft at some point and see if it goes away. I have a PST carbon fiber shaft.

 

[MYSTCHRM]

Took the car to the shop today. After driving it they believe it is a bearing in the tranny. They aren't sure why it is that I get the vibration so badly in 3rd gear, but they will investigate when they open it up. I shared my thoughts about the how the clutch may have something to do with the issues with the tranny and they believe that it's plausible. Again, don't think Spec is to blame, just that I bought the wrong clutch for my driving style.

I'll update again when I have more news.

 

[keith89]

Took the car to the shop today. After driving it they believe it is a bearing in the tranny. They aren't sure why it is that I get the vibration so badly in 3rd gear, but they will investigate when they open it up. I shared my thoughts about the how the clutch may have something to do with the issues with the tranny and they believe that it's plausible. Again, don't think Spec is to blame, just that I bought the wrong clutch for my driving style.

I'll update again when I have more news.

A bearing in the tranny would be a possibility in my case as well as I've had the input shaft replaced with a 26 spline, so who knows what could have happened. Thanks for the update.

btw I had a spec 2 before my spec 3+. I found the spec 2 drove like stock with easier pedal effort. the spec 3+ is more like an on off switch compared to the 2.

 

[MYSTCHRM]

I agree, the pedal effort was definately cut in half from the stock pressure plate. However, trying to take off or going in reverse (much worse in reverse), would shutter the car if you tried to slip it in as the clutch would just grab. It was all or nothing, no slipping. Great at the track, not so much the way I drive the car daily. I have seen others that didn't have this issue with a Spec 2 and I can't explain it. That is how it has been with my car anyway.