997.1 GT3 suspension guru opinion needed on Top Mount

[Far Cough]

I was checking my top mounts the other day and making sure all was well. I noticed that when an allen key was inserted directly into the top mount and no spanner used to hold in place the allen key and what I presume the centre rod spins "fairly" easily. The opposite side was very hard to turn in the same way and offered far more resistance. Both wheels in the straight ahead position. Is this normal or is the "loose" one slowly undoing itself internally ???

Only pic of top mount I could find


Thoughts ?

[ttdan]

Is the car level? Could be less loading on one side. Apart from that ask a real expert

[Pugley]

I am not a guru but I have rebuilt GT3 suspension.

The top mount is a spherical ball which allows the steering to rotate and the suspension to move in a small arc vertically. It bolts directly onto the top of the suspension strut.

The outer body of the shock absorber pivots around and moves up and down on this strut.

The answer is yes - the strut is free to rotate with the ball in the top mount. Due to friction it can be quite difficult to turn with an allen key but it offers little resistance when turning the steering wheel.

This friction between the top ball and mount can occasionally be the origin of some strange creaking noises from the front springs when turned during slow maneuvers and can usually be eradicated by oiling the top mount ball in its socket to reduce the "Stiction".

Well, that's my experience anyway

[sportsandclassic]

Hi,

They do work loose over time. Check that the nut is tight, when loose they will make a knocking noise from that side of the car.

Mike

[Far Cough]

ttdan said:

Is the car level? Could be less loading on one side. Apart from that ask a real expert

Yes the car is level with noone sat in it

Pugley said:

I am not a guru but I have rebuilt GT3 suspension.

The top mount is a spherical ball which allows the steering to rotate and the suspension to move in a small arc vertically. It bolts directly onto the top of the suspension strut.

The outer body of the shock absorber pivots around and moves up and down on this strut.

The answer is yes - the strut is free to rotate with the ball in the top mount. Due to friction it can be quite difficult to turn with an allen key but it offers little resistance when turning the steering wheel.

This friction between the top ball and mount can occasionally be the origin of some strange creaking noises from the front springs when turned during slow maneuvers and can usually be eradicated by oiling the top mount ball in its socket to reduce the "Stiction".

Well, that's my experience anyway

Thats very helpful thanks and kinda puts my mind at rest that the strut is not unwinding ( if that makes sense )

sportsandclassic said:

Hi,

They do work loose over time. Check that the nut is tight, when loose they will make a knocking noise from that side of the car.

Mike

Hi Mike - Thanks for your input. I can confirm the allan key part is tight in relation to the nut i.e. they both move together. It was that play you mention I was checking for as part of the winter tityvate. I just found it strange that one was significantly easier to rotate than the other. I think I`ll lubricate a plenty and see if the sticky one eases.

Thanks guys - PH to the rescue !

[Far Cough]

Top mount thoroughly soaked in Teflon based lube , so we`ll see what happens after a couple of days and after I`ve dragged it out and driven it.

[Far Cough]

Not good news - Took the car out today and immediately the front left which is the one I described as the "loose" one was knocking its head off over the tiniest of bumps. So , something is not right.

Is there a nut at the bottom that the top one tightens against ??

Off into the garage to take stuff apart ....

[sportsandclassic]

Hi,

There is not a nut below the sperical bearing (uniball). The top nut is either not secured enough or the uniball is worn and loose.

Try and see if the amount of thread stuck up through the nut is same side to side..? The nut compresses on the top of the uniball and then clamps the underside against a collar spacer which bottoms out on a washer around the damper rod.

Quite common failure on 997 top mounts. Cost around £250 a side plus fitting and geometry setup. Now I know for a GT3 cup car you can buy the (uniball)seperate but not listed for road car. Unsure what dimensions are for either.

Would be good if you could just replace the uniball if needed. Just make sure it is tight...

Mike

[Far Cough]

sportsandclassic said:

Hi,

There is not a nut below the sperical bearing (uniball). The top nut is either not secured enough or the uniball is worn and loose.

Try and see if the amount of thread stuck up through the nut is same side to side..? The nut compresses on the top of the uniball and then clamps the underside against a collar spacer which bottoms out on a washer around the damper rod.

Quite common failure on 997 top mounts. Cost around £250 a side plus fitting and geometry setup. Now I know for a GT3 cup car you can buy the (uniball)seperate but not listed for road car. Unsure what dimensions are for either.

Would be good if you could just replace the uniball if needed. Just make sure it is tight...

Mike

Thanks Mike ( again ) for your time. I`ve just been out and had another look and yes the nut ontop of the uniball was loose. God knows how as I thought it was plenty tight last time. I have now tightened it right up and the good news is the "looseness" I described earlier has gone and both top mounts now act the same i.e. give resistance. I`ll pop out for a test drive tomorrow as traffic has now gone typically friday mad !

£250 per side for a new Top mount ... eeek ! Fingers crossed it was the simple solution rather than the expensive fix as its only got low miles.

Cheers again

[Far Cough]

....and relax ! All back to normal and nice and quiet. Panic over

[sportsandclassic]

Far Cough said:

....and relax ! All back to normal and nice and quiet. Panic over

Where shall I send my in invoice ?

[Far Cough]

sportsandclassic said:

Far Cough said:

....and relax ! All back to normal and nice and quiet. Panic over

Where shall I send my in invoice ?

Just pop it in the post with me xmas card