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 Posted: May 30, 2019 03:59PM
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US
Quote:
Originally Posted by Dan Moffet
When you checked the upper dog-bone, did you check the condition of the bracket on the firewall cross-member? On my Mini, it had come loose - some previous owner had brazed it back on and of course the brazing was not good. I've read of others having the same problem.
Based on your description and your video, it sounds a lot like a problem that dogged me for months. I too experienced a loud clunk at the steering column when putting a load on the drivetrain. I posted a similar video and the suggestions ranged from a sloppy differential to a bad steering rack and/or loose subframe mounts. I too discounted the possibility of slack engine steadies mainly because they all seemed tight. 

Go back and read some of the posts on my thread [link]. I'm betting on Dan's diagnosis. That's what mine turned out to be. Good luck.


 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: May 30, 2019 08:03AM
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Quote:
Originally Posted by JayB
Quote:
Originally Posted by Dan Moffet
Glad you came back.
In your video, all I hear is gear train slack. To me, it sounds more or less normal in the video. Others with more experience can advise whether it sounds excessive.

When you turn one wheel like that, (assuming the transmission is in gear), there is a minute amount of slack in each gear mesh that adds up - axle turns the diff main wheel gear, which turns the crown gear which turns whatever gear you've got the transmission in, which turns the transmission input shaft, which turns the drop gears, which tries to turn the stopped engine.  When you turn the wheel the other way you take up all those small bits of slack in the other direction.

Good video by the way!
Ha..  Thanks its not one of my best videos though.

I'm about at my wits end with this.. lol..  Feels like someone is taking a bat to the steering column when i'm not carefully timing my shifts.. or if I just take my foot on and off the gas when I'm high in the rpm's...

Thanks for your quick response Dan!!  I guess i'll wait for a few others to chime in..
Check that the castle nut on the end of the CV is torqued to spec. You can check for play by jacking up the car and pushing and pulling on the wheel at 12 and 6 o'clock there should be no play at all.
To check the torque remove the front wheels it is the big nut in the middle of the four wheel studs, remove the split pin and check the torque with disc brakes it needs to be up to 180lbs.

If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: May 29, 2019 10:16AM
 Edited:  May 29, 2019 10:25AM
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Drive train slack in the Differential to be more direct .. 

 Cross pin + Spider gears   


  Parts in question:

https://photos.app.goo.gl/rfGb4LCb1TB9KyMA8




Its a sign of a worn differential.  too much abuse it will shoot parts out of the case. (shock to the system type clutch drops or hard shifts) 
  Be nice to it and it will last a long while, but in the end you dont want to blow a case or anything.
 
its an Engine out job.. Not horrible to only refesh the differential.. but if you're having other shifting issues by chance.. nows the tear into and replace other parts time ..   Synchros are also common to  wear in and cause cruchy 1-2 shifts.. plus plenty other things!

Goodluck

 Posted: May 28, 2019 03:49PM
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Quote:
Originally Posted by Dan Moffet
Glad you came back.
In your video, all I hear is gear train slack. To me, it sounds more or less normal in the video. Others with more experience can advise whether it sounds excessive.

When you turn one wheel like that, (assuming the transmission is in gear), there is a minute amount of slack in each gear mesh that adds up - axle turns the diff main wheel gear, which turns the crown gear which turns whatever gear you've got the transmission in, which turns the transmission input shaft, which turns the drop gears, which tries to turn the stopped engine.  When you turn the wheel the other way you take up all those small bits of slack in the other direction.

Good video by the way!
Ha..  Thanks its not one of my best videos though.

I'm about at my wits end with this.. lol..  Feels like someone is taking a bat to the steering column when i'm not carefully timing my shifts.. or if I just take my foot on and off the gas when I'm high in the rpm's...

Thanks for your quick response Dan!!  I guess i'll wait for a few others to chime in..

 Posted: May 28, 2019 03:14PM
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CA
Glad you came back.
In your video, all I hear is gear train slack. To me, it sounds more or less normal in the video. Others with more experience can advise whether it sounds excessive.

When you turn one wheel like that, (assuming the transmission is in gear), there is a minute amount of slack in each gear mesh that adds up - axle turns the diff main wheel gear, which turns the crown gear which turns whatever gear you've got the transmission in, which turns the transmission input shaft, which turns the drop gears, which tries to turn the stopped engine.  When you turn the wheel the other way you take up all those small bits of slack in the other direction.

Good video by the way!

.

"Hang on a minute lads....I've got a great idea."

 Posted: May 28, 2019 02:14PM
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(Video Link Below)
So, here we are months later...  I think I have pretty much ruled out a motor mount, bushing or steady bar..  also along the way the car got new calipers, drums, shocks and some other bits...

But this issue still persists.. With both front wheels off the ground I managed to duplicate the noise...

Any new ideas?

Video -> https://vimeo.com/338987297/98bb436fcb

 Posted: Sep 5, 2018 04:40AM
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CA
Get a friend to help, but not on a lift or jacked up. You need the wheels on the ground to generate torque against the motor and subframe mounts. Try rocking the car forward and back hard as you can in all gears with the engine off. The car will move a bit until you get the slack out of the gear train, then the car momentum will apply torque to the mounts and you should see the engine rock or move or the subframe shift.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Sep 4, 2018 02:09PM
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Quote:
Originally Posted by Dan Moffet
Quote:
Originally Posted by JayB
Quote:
Originally Posted by Alex
Have checked all the subframe mounts ?
The rear ones can punch a hole through the floor...
Checked that out... Looks like the owner before me did a repair there....  The mount looks not torn and attached, and the mount itself looks kind of recent…. 

The rear mounts that attach to the floor pan may be fine - it's the floor pan metal that gets torn from meal fatigue.
Are your subframe tower bolts torqued to spec?

I pulled the carpet and see a repair has been made to the floorpan… I'm going to do what I did again with the carpet moved to see if I can notice anything moving from in the car...  I can tell you that the subframe bolts are tight...  Not to spec because of a lack of torq wrench, but feels like its tightened to the end of the threads and seated at the bottom of the unthreaded part.

Its difficult to diagnose on my own when I cant see what's going on under the hood when I'm putting a load on the motor...  I think I might have to get this car on a lift and have some friends look at it while I'm on and off the gas.... 

 Posted: Sep 3, 2018 05:44AM
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CA
Quote:
Originally Posted by JayB
Quote:
Originally Posted by Alex
Have checked all the subframe mounts ?
The rear ones can punch a hole through the floor...
Checked that out... Looks like the owner before me did a repair there....  The mount looks not torn and attached, and the mount itself looks kind of recent…. 

The rear mounts that attach to the floor pan may be fine - it's the floor pan metal that gets torn from meal fatigue.
Are your subframe tower bolts torqued to spec?

.

"Hang on a minute lads....I've got a great idea."

 Posted: Sep 3, 2018 12:49AM
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GB

Urghhhh....

Very difficult to diagnose at distance, even with the video.

Certainly sounds drivetrainish.  So many things it could be from simple to terrible.

Have you gat any friendly locals with experience ?

 Posted: Sep 2, 2018 12:50PM
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Quote:
Originally Posted by Alex
Have checked all the subframe mounts ?
The rear ones can punch a hole through the floor...
Checked that out... Looks like the owner before me did a repair there....  The mount looks not torn and attached, and the mount itself looks kind of recent…. 

Here's a video where I tried to capture the thunk… 

 Posted: Sep 1, 2018 07:57PM
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GB
Have checked all the subframe mounts ?
The rear ones can punch a hole through the floor...

 Posted: Sep 1, 2018 06:21PM
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Got the new subframe bushings in.... The ones for the top two large bolts....  I want to say its a little better...  But that sensation is still there...

So now I have brand new..
Motor Mounts x2
Upper Dogbone
Added the two additional lower front dogbones (left and right)
Front top (x4) new subframe bushings...

I would of sworn this would of taken care of it because of the gap in the old bushing on the drivers side... the one between the top of the tower and the body of the car.....

 Posted: Aug 29, 2018 09:09PM
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GB
Waggle the steering wheel quickly from side to side while watching the tower bolt - you'll be terrified at how much movement there is.

I'd suggest solid mounts rather than poly or rubber, the poly ones disintegrate over time like the rubber ones do.

 Posted: Aug 29, 2018 01:08PM
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CA
Quote:
Originally Posted by JayB
Quote:
Originally Posted by Dan Moffet
When you checked the upper dog-bone, did you check the condition of the bracket on the firewall cross-member? On my Mini, it had come loose - some previous owner had brazed it back on and of course the brazing was not good. I've read of others having the same problem. On mine, it looked fine until I took the bolt out and found the plate that would go under the master cylinders on a right-hand car had suffered metal fatigue and torn a larger hole around the dog-bone bolt. I only discovered this when trying to eliminate an annoying "crack" sound coming from the right side floor. The whole subframe was moving a bit and caused metal fatigue in the floor pan.
In checking it, I actually removed it from the engine first and tugged on it a little....  But I'm going to go over it all again...
Yes, remove the bolt and dogbone from the firewall end and inspect the brackets.  Before you do, you can check for engine movement by putting it in 4th gear (engine off and handbrake released), raising the bonnet and pushing/pulling the car back and forth by the slam panel. The top of teh engine shouldn't move noticeably - if you can see movement with just your body strength, the engine torque would do a lot more.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Aug 28, 2018 08:03PM
 Edited:  Aug 28, 2018 08:32PM
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Quote:
Originally Posted by Alex
Check the subframe mounts - the rubbers around the tower bolts, the teardrop mounts at the front, and the lower rear floor mounts.
Never thought to check those....  Makes sense....  I'm on it.. Hopefully I can easily tell by looking at them....  lol..

Edit / Addition***

Ran out to the car because I felt this had to be it... The right side upper bolt had enough room under it where I could feel the space with my finger.... So this looks like it is definitely the cause... Not only is the bushing bad the bolt is not tightened.. gheez….  Im going to snug it tomorrow and order some new bushings...

let you know the outcome!  Thx

 Posted: Aug 28, 2018 08:00PM
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Quote:
Originally Posted by Dan Moffet
When you checked the upper dog-bone, did you check the condition of the bracket on the firewall cross-member? On my Mini, it had come loose - some previous owner had brazed it back on and of course the brazing was not good. I've read of others having the same problem. On mine, it looked fine until I took the bolt out and found the plate that would go under the master cylinders on a right-hand car had suffered metal fatigue and torn a larger hole around the dog-bone bolt. I only discovered this when trying to eliminate an annoying "crack" sound coming from the right side floor. The whole subframe was moving a bit and caused metal fatigue in the floor pan.
In checking it, I actually removed it from the engine first and tugged on it a little....  But I'm going to go over it all again...

 Posted: Aug 28, 2018 04:39PM
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CA
When you checked the upper dog-bone, did you check the condition of the bracket on the firewall cross-member? On my Mini, it had come loose - some previous owner had brazed it back on and of course the brazing was not good. I've read of others having the same problem. On mine, it looked fine until I took the bolt out and found the plate that would go under the master cylinders on a right-hand car had suffered metal fatigue and torn a larger hole around the dog-bone bolt. I only discovered this when trying to eliminate an annoying "crack" sound coming from the right side floor. The whole subframe was moving a bit and caused metal fatigue in the floor pan.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Aug 28, 2018 01:12AM
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GB
Check the subframe mounts - the rubbers around the tower bolts, the teardrop mounts at the front, and the lower rear floor mounts.

 Posted: Aug 27, 2018 08:55PM
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More description of issue....  Sounds like the same thing I hear often...  If I don't time my shifts where they are pretty smooth I feel like the engine is banging around under the hood...  Like a hard thud..  Its bad in 1st and 2nd... But its easy to have it happen in any gear... I can also drive and nobody would know its an issue, if I was careful....  ALSO.... if I'm not on the clutch and in gear just going down the road, if I come off and on the gas hard that would also make this bang feeling...

Its a funny thing.....  This is something that I would think be a faulty upper stabilizer or motor mount...  and I have had them in the past....  So I had to do some work on the car so I ordered new front lower motor mounts, the MiniMania front lower dogbone mounts both sides and new bushings for the top right hand side one..... 

I was shocked when it didn't go away.... 

Maybe someone here can point me in a different direction...  Because I thought I had this figured out... 

Thanks in advance!!

1991, 998, RHD, Manual