Creaking sub-frame?

[3C4M Guy]

Apologies if this has been raised before. The front suspension on my B6 Passat has been creaking ever since upgrading springs, shocks, sway bars and lower control arm bushes - particularly when just one front wheel is run up a slope. At first I suspected that the Whiteline rear urethane bush on the front control arm was the culprit. However I’ve read it’s not uncommon for the front sub-frame to creak on Golf MkV and Passat B6 once it’s been lowered and re-fitted. It does seem critical to replace the sub-frame stretch bolts to achieve the correct torque. However both ECS Tuning and TyrolSport sell a kit to prevent this noise.

The ESC Tuning product is just a shim to stop the noise, but the sub-frame can still potentially move. ECS Tuning: VW MKV Subframe Spacer Plates Install - YouTube

The TyrolSport product is a kit of collars that prevent any movement. TyrolSport Deadset Rigid Subframe Collar Kit - Mk5 / Mk6 / B6 Passat / CC / Audi A3 / TT (ngpracing.com) As I see it, the main disadvantage of this kit is it does not allow the sub-frame to be adjusted to help with wheel alignment e.g. matching the camber on each side.

Has anyone had any experience with eliminating this noise?

[Lucas_R]

Did you replace the upper strut mounts and bearings when doing your suspension work? These are a common cause of noise.

Also, are your sway bar end links original or did you replace those with new/aftermarket items.

[3C4M Guy]

Did you replace the upper strut mounts and bearings when doing your suspension work? These are a common cause of noise.

Also, are your sway bar end links original or did you replace those with new/aftermarket items.

No I didn't and I should have because the driver's side strut mount & bearing & mount noisy. I've replaced both mounts & bearings now and also the sway bar end links. It's amazing how the ball joints on the links can create a knocking sound. It took me ages to work out what was causing the knocking sound at the rear.

I'm doing a front suspension refresh now because the upgrade was a few years ago. I also found that two of the front sway saddle clamp bolts had worked loose so I've replaced them all with fresh stretch bolts. The last step now is to eliminate the creaking noise ... assuming it's still there. I have some solid rubber Audi TT Febi bushes in the original Passat rear mount for the lower control arm if I think they would be better than the Whiteline polyurethane ALK.

I guess I could drive the car and see if the creaking is still there and then look at the sub-frame if necessary but it would be nice to tackle everything whilst the car is up on jack stands.

[Umai Naa!!]

70Nm +90deg isn't enough to stop the creaking.

Go over the 4 18mm ones again with a long breaker bar. You'll probably get another 90deg out of them before you get that 'tight enough' feeling.

[3C4M Guy]

70Nm +90deg isn't enough to stop the creaking.

Go over the 4 18mm ones again with a long breaker bar. You'll probably get another 90deg out of them before you get that 'tight enough' feeling.

Thanks Umai Naa! I'll try that. I've got a massively thick and long breaker bar for just these occasions. I've got 4 new M12 stretch bolts with 18mm heads to use after I've done another job. I've also ordered some of those thin sub-frame spacers from ECS Tuning. Would you recommend using them?

[Passat my07]

Were all the suspension bushes tightened when the car was at ride height? Otherwise the bushes might be getting overstretched. This is often a problem when cars are lowered.

[3C4M Guy]

Were all the suspension bushes tightened when the car was at ride height? Otherwise the bushes might be getting overstretched. This is often a problem when cars are lowered.

Thanks Passat my07. Any bushes that needed to be tightened when the car was lowered on the ground were done that way.