Technical Front strut assembly.

[DaveMcT]

I have just rebuilt a front strut with new spring. The thrust bearings are good.
It has a stepped nut above the rubber top mount but when tightened it stops the thrust bearing moving correctly.
I can’t believe this is right. I suspect the step on the special nut is not deep enough and so fouls on the rubber mount.

How do I check for this? I believe the rubber top mounting should turn freely. This one is stiff.

I have checked the AutoDoc video on YouTube. The strut goes through the bearing and the top spring seat bears on the bearing lower race. The stepped nut holds it all together. But seems to drag on the rubber mount.

Help!

 

[jackwhoo]

Hi,
Struts often dont feel right when the spring pressure is being retained by the damper nut rather that the top mount transmitting the spring load to the vehicle structure. Is this one of those situations?
Best wishes
Jack

 

[The Panda Nut]

If possible post a photo. The bearing will feel stiff with the strut out of the car as stated above. Make sure your torque settings for the retaining nut and strut top are good and it will be fine. If I remmeber right when you tighten the piston top nut it does feel odd as it tightens onto the strut top mount but if you adhere to the correct torque (48lb/ft) you cannot really get this wrong just ensure the spring seat is acurately alligned with the strut and the mount is the right way round pointer to the rear. If you dont align the spring seat correctly you can get clunking from the springs as they dont seat properly. (Top and bottom seats not aligned) I found the new bearings felt tight on the steeringfor several miles and I was concerned they were too tight. They eased and have been fine since 50 to 100 miles or so. It sounds as if you are doing OK. Hold your nerve!

 

[DaveMcT]

Hi,
Struts often dont feel right when the spring pressure is being retained by the damper nut rather that the top mount transmitting the spring load to the vehicle structure. Is this one of those situations?
Best wishes
Jack

Thanks Jack. The steering was very stiff on this car so I suspect there is an issue with both top mounts. The bearings however are both good as new. I had expected to need replacements.

I tried pressing down on the mounting while turning but it could feel no different at all. I suspect this particular mount has a little too much rubber so I've put a 1mm washer between the top of the bearing and the stepped nut. It feels better. Not loose and spinning but more free moving. If it causes a clunk I'll have to take it apart and remove the washer.

 

[koalar]

are you sure the the top mount and nut match

there more than one type

normally have a standard nut I see. Does it needs to go wide side down ?

 

[DaveMcT]

The car had stiff steering when I bought it. I assumed the top bearings were worn. However, the bearings are actually really good as are the mountings. I stripped and cleaned everything and reassembled. When done, the top bearings were just as stiff.

The sequence is -

Strut - spring - top spring seat - bearing - rubber mount - stepped nut (step down). The top retainer ring and self locking nut are added later.​

The thrust bearing has a 12mm hole in the top side that goes over the threaded top end. The larger diameter bottom side goes over the strut leg and also aligns the top spring seat. This puts rotation force into the bearing rather than turning the shock shaft inside the damper.

The stepped nut goes into the rubber mount and traps the bearing against the strut leg shoulder. If you bolt it up without the rubber mounting, the bearing will turn freely (as it should). In my case, fitting the top mount made it very stiff. I have guessed the step in the nut is too shallow (unlikely) or the mounting is too thick - it is rubberised on both sides. I have added a 1mm washer and below the stepped nut. The mount now turns better though there is still some drag from the rubberised top surface. This might generate a clunk so I will have to see how it goes.

 

[vexorg]

It shouldn't be too hard to see why it's stopping turning, but the videos for panda seem to show it's free when tightened (I imagine it would be based on other cars I've done)

 

[koalar]

I'd assemble it without the spring, to test

there's quite a few different top mounts on ePer

diesel
petrol
diesel 4x4
petrol 4x4

I have only messed with the petrol none 4x4 but they have had an ordinary nut, what happens if you assemble with the nut the other way round

ePer only show one part number for the nut ?

 

[DaveMcT]

I'd assemble it without the spring, to test

Yes I did that and concluded it needed a shim washer.

I have not tried a different mount (I have a Febi) but these fit the car, "look" correct and the bearings are correct. There seems to be a fraction too much rubber on these mounts but I'm not about to pay OEM prices just to find out. The 1mm washer has "free'd up" the bearing rotation with no rubber binding on the nut corners.

I will report back when the car is on the road.