severe vibration after t5 swap

Dan_Fish_Pro

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Nov 5, 2023
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8
OH
66 mustang swap from 3 speed manual to 1987 GT t5 borg warner, severe vibration in neutral, in and out of gear, vibrates in all gears on road, vibrates with engine turned off coasting, mechanic that installed says tranny bad. Need second opinion
 
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66 mustang swap from 3 speed manual to 1987 GT t5 borg warner, severe vibration in neutral, in and out of gear, vibrates in all gears on road, vibrates with engine turned off coasting, mechanic that installed says tranny bad. Need second opinion


Where did the trans come from exactly?

I'm a bit surprised you didn't go through the thing before installation particularly, if it was an unknown.

What flywheel did you use? The one that came with the trans?
 
If the engine is off, and the clutch is pushed in, and you are coasting, then the vibration is from the driveshaft, something internal to the transmission, or wheel/tire.
The driveshaft can cause vibration due to out of balance or bad u-joint. The output shaft bushing in the tailshaft of the transmission could be severely worn.
Although, if the pinion angle/driveshaft to transmission angle is way off, that can also cause a vibration. Usually harmonic.
If the engine is off, but the clutch is engaged, then you are spinning the engine over and the flywheel, clutch or engine can be a cause.
 
vibration occurs sitting still with engine in neutral, so would not be driveshaft. also was not making vibration before swap, so would not be wheel/tire. mechanic said angle/driveshaft was correct. engine was off , coasting in neutral still vibrated, so don't think anything in front of tranny(clutch, pressure plate, flywheel). I'm still thinking tranny bad??
 
I , personally, don't know anything about how to inspect t5 and can't find anyone in southern ohio that will work on a t5. Does anyone know anyone in ohio that works on t5? I tried all the local tranny shops, they won't touch it?
 
vibration occurs sitting still with engine in neutral
Sounds like a flywheel issue to me(IE: mixing a 50oz flywheel with a 28oz balancer or vice versa) Nothing else that it could be if it vibrates in neutral right? Aside maybe from a defective pressure plate or something of that nature. Regardless, without knowing what parts were used its not likely we can diagnose it from the internet
 
Correct pilot bearing? There's a different one for V8 and 4cyl T5's. Are you certain the T5 taken from the 1987 is a V8 model? The 4cl pilot shaft is smaller, so putting a 4-cyl T5 into a car with a V8 pilot bearing would create vibration from the input shaft wobbling.

The V-8 input shafts are 0.668 and the 4-cyl are 0.590 inches.


EDIT: Saw that you said it vibrates in neutral? Try this. Put it in 1st gear, and push the clutch in. Does it still vibrate? If so, it's NOT the transmission. That would hold everything in the T5 still including input shaft and the clutch disk. The flywheel and pressure plate however are still spinning.
 
Correct pilot bearing? There's a different one for V8 and 4cyl T5's. Are you certain the T5 taken from the 1987 is a V8 model? The 4cl pilot shaft is smaller, so putting a 4-cyl T5 into a car with a V8 pilot bearing would create vibration from the input shaft wobbling.

The V-8 input shafts are 0.668 and the 4-cyl are 0.590 inches.


EDIT: Saw that you said it vibrates in neutral? Try this. Put it in 1st gear, and push the clutch in. Does it still vibrate? If so, it's NOT the transmission. That would hold everything in the T5 still including input shaft and the clutch disk. The flywheel and pressure plate however are still spinning.
The different pilot bearings result from the different crankshaft hole diameters between the 2.3 and the 5.0(and possibly how the input shaft length interacts with the different engines, IE: some engines have an "extended" pilot bearing to make up for a shorter input shaft) The only way it could be anything pilot bearing related would be if the pilot bearing was just bad(which is possible...I personally prefer bronze pilot bushings most times since there are no bearings to go bad...but pilot bearings are a bit smoother)
 
The different pilot bearings result from the different crankshaft hole diameters between the 2.3 and the 5.0(and possibly how the input shaft length interacts with the different engines, IE: some engines have an "extended" pilot bearing to make up for a shorter input shaft) The only way it could be anything pilot bearing related would be if the pilot bearing was just bad(which is possible...I personally prefer bronze pilot bushings most times since there are no bearings to go bad...but pilot bearings are a bit smoother)

But you are missing the part about the V8 T5 and the 2.3L T5 having different input shaft diameters. The 4cyl box will bolt up to the V8 bellhousing and the input shaft is the proper lenght, but the tip is a much smaller diameter than the V8 gearbox.

So if you install a standard 5.0 pilot bearing, which is designed for a input shaft with a diameter of 0.668" and then bolt up a 2.3L T5 which has a input shaft tip diameter of 0.590" then it's going to be hanging in the breeze and not making any contact with the bearing and will be unsupported.

Lots of folks run 2.3L T5's in fox mustangs, but you need to use a specific ranger pilot bearing which will fit in the 302 crank and accept the smaller 2.3L tip. If you don't, no support is made and you end up with vibration. Have seen this happen quite a bit.

Hence the question to the OP if he is 100% sure the T5 is a V8 T5. Just because it came out of a GT doesn't mean it's a proper V8 spec box. Lots of 2.3L T5's got swapped into V8 cars over the years.
 
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So... The end of the transmission input shaft needs to be measured.
standard 5.0 pilot bearing, which is designed for a input shaft with a diameter of 0.668"
2.3L T5 which has a input shaft tip diameter of 0.590"

I'm putting this here so I can add it to the page (we have someplace :chin: ) later on.

My crystal ball tells me we're not finished yet tho. :O_o:
 
I would check into the pilot bearing clearance like stated above
I would also do all that work yourself to save hassle in the long run
Why have a mechanic do that easy job in the first place?
It probably was mechanics error
Unless he is well versed in swaps that would be a very easy mistake to make as a tech
If you take it back to him, you are liable to get the CYA treatment and subsequent noise from him
Have someone else pull the trans and check it out
Like yourself
Did you discuss with him the possible pilot bearing differences when he said the trans must be the problem?
 
EDIT: Saw that you said it vibrates in neutral? Try this. Put it in 1st gear, and push the clutch in. Does it still vibrate? If so, it's NOT the transmission. That would hold everything in the T5 still including input shaft and the clutch disk. The flywheel and pressure plate however are still spinning.


OP hasn't returned, but I would still like to answer this question if he does.

With the clutch pushed in in nuetral, put the trans in gear. At this point, everything in the trans is stopped including input shaft and clutch disk. Does it vibrate here?

If no. Shift trans to nuetral gear, and let the clutch out slowly. Does it instantly start to vibrate?
 
Right, there are ways to narrow down a pilot bearing failure or input shaft wobble
He said it vibrated going down the road with the engine off
That means the driveshaft or trans to me (not mechanics error)
Probably had a bad u joint and the OP is done for now
 
ok, it's been a while. current situation: As i stated before, severe vibration with tranny in car sitting still in neutral or any gear, tranny is now out of out of car with clutch and pressure plate still on and no vibration. input shaft measurement is good, pilot bushing fits good, what next?? Any help would be appreciated. Mechanic still says it is the tranny, but how could that be with car in neutral sitting still, I don't think tranny would be moving that much when sitting still in neutral or any gear with clutch depressed!
 
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The only thing turning sitting there in neutral is the input shaft of the trans
Besides the engine of course
If you are sure it does not vibrate with the trans out and gone?
The only thing left is the front input bearing and first gear in the trans
Replace both of those
Do some shaft clearance checks in the 5 speed gearbox just for GPs
If you have too much clearance in either of those shafts you will have vibration
Selective fit shim washers adjust that clearance\You make sure yours are perfect and within spec
 
Grab the input and output shaft together. Can you push them in and out? There will be some side to side wiggle, but what we are looking for is endplay in and out from each end, especially the input shaft.

like said, the only thing spinning in neutral in a T5 would be input shaft, and countergear at bottom of trans case.

Are you handy enough to pop the top cover off the T-5 and have a look at the input and countergear to inspect and see if partial teeth are missing somewhere?
 
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