We just got done swapping my '05 MCS engine and tranny into my '02 MCS after it threw a rod bearing a few years ago. The swap went remarkably well and the only thing that gave us fits was the clutch slave cylinder. It was leaking so we got a new one and solved that issue. Went out for a test ride for the past days and noticed a driveline vibration. The vibration disappears when accelerating and reappears when you lift off the gas and are under no load. The symptoms are that of a bad driveline universal joint in rear whell drive car. We have fixed this type of issue on our BMW's before but this Mini work is the first we have done on a front wheel drive car.
Looking at all the posts I could find I would assume it's one of the axle shaft assemblies. One thing puzzles me.........2 weeks ago before we did the swap the car was running fine with no vibration. We did not swap any driveline parts when we did the swap, we used the originals.
Is there a way we could have put the driveline back together the wrong way to cause the vibration??
What should we be looking for??

Thanks guys,

Tom in PA

 

Could be the rear wheel bearing gone bad. Is there a droning sound and is it located to one side of the car?

 

It's definitely not a bearing sound. It's a 'thump=thump' type, cyclical sound, similar to bad universal or flex disc of a RWD BMW.
At front of car for sure, in driveline.

Tom in PA

 

You can double check your diagnosis by putting the car in neutral, and making sure it isn't tied to engine RPM. If all the mounts are tight, it probably is a CV joint. If I read your post correctly, the car sat for years. Easy enough for one to rust up and go bad.

 

The car did sit idle in the shop for 4 yrs before we decided to fix it. Long story!
Three weeks ago we had the car out prior to swapping the engine even with the bad bearing as we knew we were swapping the engine/tranny. At that time we had no driveline issues at all. Car ran fine other than the rod knock.
The issue only showed up after we took everything apart and put it back together. When we did the swap we pulled subframe, et all , out the bottom and then we disconnected everything for the swap. The axles are original to the car.
Did we do something wrong when installing??

Thanx

Tom in PA

 

In this situation here's what ill do.
Rechecked installation and retorque all bolts.
Like someone said put on nuetral and Rev the engine.
Put front of car on Jack high enough to raise the tires off the ground and run car on gear. Make sure you put chocks on rear tires front and back. Its risky but I do it.

 

HRM,
I did put the car in neutral and the noise is non-existent. Definitely not engine related. I just drove back home about 20 miles and I have another bit of info. I was climbing a small hill with a RH and LH curve. Turning right up the hill the noise got worse even under acceleration. At the top of the hill I was winding it up and turning left and the noise went away until I straightened it out.
I need to get it on the lift tomorrow.

Tom in PA

 

I wonder if the short shaft seated and locked on the differential.

 

Sounds like a bearing to me. Maybe the castle nut isn't torqued enough, but noise that varies with turns is often a bearing.

 

If its a bearing it will constantly make a noise.

 

I'll check the bearings tomorrow although we did not disassemble any of the front end components. The 'thump-thump' is not a usual bearing noise which is why I was focusing on the axle shafts and joints. The right and left turn scenario I described above leads me to believe that one of joints may be locking up when turning one way and not the other. Doesn't quite make sense to me so I have to get in on the lift.

Tom in PA

 

I have found at the start some only make noise during turns and as they get worse make noise all the time. Anyway it is just a 500 mile internet guess.

Thumping though isn't usual. How about a square tire? Maybe you moved the rears to the front and notice it now because of that. Sitting 4 years, especially if low or flat will take a tire out of round, perhaps forever.

 

Tires and wheels are out as we installed new tires and re-balanaced prior to our first test run out before the swap. We did all that type of work and got it inspected prior to the swap.
We're going to put it on the lift after work tonight and see if we can't see something obvious when turning the wheels by hand or under power. I would think with the noise I am hearing when running we should get something while not under power.

Thanks for the all the help.
I'll keep you posted,

Tom in PA

 

Tom,
It sounds like you may have made my mistake years ago on a different type of car. When you pulled the drive axles loose, did you maintain a straight angle or did you bend one of the joints? If a particularly old drive axle is bent outside of its normal range of motion, the smooth working surfaces can become damaged by debris from the old grease or unsmooth areas of the cv joint itself.

The other possibility is particular to old drive shafts. When the shafts wear they make a groove in the normal operating area. when they are disturbed after being in the same place for years, the drive angle may have changed ever so slightly enough that where the cv is now, allows the joint to travel just outside of that worn in section causing the awful vibration and only under load. Below is a pic of a severe case on a nitro RC car for reference.

Hope you get it figured out!

 

if the axles is bended, the only way to solve this is change the drive shaft?? or any other way to solve it?