Rear End Question

[IWantAFox]

Hello, I was just changing the u joints in my 92 LX, and noticed that when I spin the wheels they both turn in the same direction. Is this normal? I tried to hold one wheel still and spin the other but it wouldn't move. I am not too familiar with the TracLoc rearend and when the clutches engage/disengage. I hope I am just freeking out over nothing. I know there was an old drag racing trick you did by welding something together in the diff. and I hope that the rearend wasn't fooled with. I ask because I have a vibration when I coast in neutral from 60 mph. I am in the process of changing u joints, hoping that is the problem, although they seem fine to me. ANY help or comments are greatly appreciated. It is a V8 car with a 5 Speed. THanks

 

[willys1]

Hello, I was just changing the u joints in my 92 LX, and noticed that when I spin the wheels they both turn in the same direction. Is this normal? I tried to hold one wheel still and spin the other but it wouldn't move. I am not too familiar with the TracLoc rearend and when the clutches engage/disengage. I hope I am just freeking out over nothing. I know there was an old drag racing trick you did by welding something together in the diff. and I hope that the rearend wasn't fooled with. I ask because I have a vibration when I coast in neutral from 60 mph. I am in the process of changing u joints, hoping that is the problem, although they seem fine to me. ANY help or comments are greatly appreciated. It is a V8 car with a 5 Speed. THanks

If the wheels spin in the same direction it means you have a posi rear.If they spin in opposite directions you dont have a posi unit.

 

[IWantAFox]

Thanks for the info. Sometimes the dumb questions need asked anyway. Do you have any idea what the vibration could be?

 

[HISSIN50]

So the vibe occurs under load but not when coasting? Does it matter what the absolute speed is?

Good luck.

 

[IWantAFox]

It is worse with the car in neutral coasting from high speed. I can also feel it when the car is in between 4th going into 5th. I am starting to fear a warped flywheel or worse yet, a harmonic balancer problem. What do you guys think?

 

[HISSIN50]

If it is only when the driveline is unloaded, I would not be fearing either thing you listed as much as something like a pinion angle issue. Hard to make those calls from online descriptions (it's hard to articulate the symptoms exactly, and hard for us to interpret it and try and toss a couple cents into the hat).

Good luck.

 

[IWantAFox]

Any kind of suggestions is cool with me. I am somewhat mechanically inclined and just need someone to point me in the right direction.

 

[willys1]

Any kind of suggestions is cool with me. I am somewhat mechanically inclined and just need someone to point me in the right direction.

You mite want to take it to a mechanic to check the rear end..It could be a # of things!!

 

[bill302]

It is worse with the car in neutral coasting from high speed. I can also feel it when the car is in between 4th going into 5th. I am starting to fear a warped flywheel or worse yet, a harmonic balancer problem. What do you guys think?

if it is worse with the car in neutral coasting from high speed i would think tire or wheel balance axle or driveshaft- when was the last time your tires were balanced you will be surprised what a unbalanced tire or wheel will do on my escort i could not drive over 75 mph until i had my tires rotated and balanced now at 85mph drives like new.... any comments on my reply i'm guessing on axle and driveshaft but have experienced wheel and tires being unbalanced with his discription of problem...

 

[IWantAFox]

if it is worse with the car in neutral coasting from high speed i would think tire or wheel balance axle or driveshaft- when was the last time your tires were balanced you will be surprised what a unbalanced tire or wheel will do on my escort i could not drive over 75 mph until i had my tires rotated and balanced now at 85mph drives like new.... any comments on my reply i'm guessing on axle and driveshaft but have experienced wheel and tires being unbalanced with his discription of problem...

Just had them done yesterday.

 

[willys1]

Just had them done yesterday.

did the car recently have gears put in?

 

[bill302]

Just had them done yesterday.

i see your on top of it i'm confident you will find the problem before long keep digging you have not finished replacing u-joints yet or have you? and if not let us know outcome, does it fix problem ect...

 

[IWantAFox]

did the car recently have gears put in?

The car is new to me, and the previous owner advertised 3.73's, but I don't know how long ago they were installed (or who installed them).

I will post what I find out tomorrow. Going to take the driveshaft to work with me, because they have a nice vice and if needed an arbor press. (Getting paid to work on my car is sweet.)

 

[willys1]

The car is new to me, and the previous owner advertised 3.73's, but I don't know how long ago they were installed (or who installed them).

I will post what I find out tomorrow. Going to take the driveshaft to work with me, because they have a nice vice and if needed an arbor press. (Getting paid to work on my car is sweet.)

Is it the factory drive shaft?

 

[IWantAFox]

Is it the factory drive shaft?

Yes, I believe it is. it is not aluminum.

 

[willys1]

Yes, I believe it is. it is not aluminum.

When I got my 373's in it caused a "really bad" vibration at high speeds!! I bought an FMS Aluminum drive shaft and the problem was solved!!

 

[Michael Yount]

If it were flywheel/clutch related, it would likely vary with ENGINE speed, not driveline speed. As Willys said, many people experience driveshaft-related vibration after installing gears. Keep in mind, when the 2.73's are swapped out for 3.73's, the driveshaft is turning almost 37% faster all the time. Any little shimmy/vibration/shake shows up pretty quickly when you spin it faster.

 

[IWantAFox]

UPDATE. The u-joints didn't help (at least they are done). I took a ride tonight and paid attention. The vibration is all the time, its just more noticeable at a coast. Its from 55 mph up to around 75 mph. I would say it happens around 2000 rpm. And it shakes sitting still with the car in neutral and I think its a little worse with the clutch pressed in (again above 2000 rpm). I am starting to think transmission now. (pressure plate, flywheel??) There isn't any problems shifting gears or hitting reverse......I am stumped......any more ideas fellas? I am probably gonna break down and take it in.

 

[1mild88lx]

Drive shaft, I had the same problem.

 

[IWantAFox]

I am going to jack the back end up and index the driveshaft/tailshaft in the 3 other positions I have left. Are they balanced on the car from Ford? I have came to the conclusion that I have 2 different causes. The part that vibrates at a coast is probably the driveshaft, and the vibration at a stop, in nuetral revving the engine to 2500rpm, is yet to be defined. (Although, I would be happy just to get the coasting vibe to go away, since its the worst)

Checked the harmonic balancer and It LOOKS ok

Just a quick question. The clutch spins with the tranny, and the flywheel/pressure plate spins with the engine, correct?

Anyone have an aluminum driveshaft for sale on the cheap?