The MK4 top mounts are one of the biggest issues with the suspension of the VW MK4 platform. The spring cap rises up out of the top mount and this is a huge problem despite forums saying it’s okay.
Top Mount Inserts
I’ve tried top mount inserts and you can read about them here. Long story short they are a huge improvement over having a gap between the cap and the body of the car.
Having said that they are not perfect because they still allow the top of the damper rod to move laterally. To such an extent I think I can feel the suspension geometry changing as the load on the front suspension changes.
Options – MK4 Top Mounts
There are two options with regards to getting MK4 top mounts that don’t collapse.
Polyurethane items or sold metal top mounts with bearing that are camber adjustable.
I oood and ahhhd over this for months before deciding on going with polyurethane top mounts.
Why Polyurethane?
My thinking was they are cheaper and if they don’t do what I want I can always go with camber adjustable top mounts in the future.
I went with Strongflex top mounts in the softest compound. Installation was super easy and their dimensions looked the same as the stock bushes. In short they were a straight swap.
Verdict – Polyurethane Top Mounts
The issues with the geometry seeming to change in corners has gone, as far as I can tell. And I’ve only had them on for about 2000KM but I don’t see any sign that they will collapse.
Ride comfort seems completely unaffected and there is no extra noise or harshness from them.
If you are looking for something that is as civilised as the stock bushes but lasts longer, so far I think they are a win.
On the performance front I’ve got a lot more confidence in the front end because it behaves consistently. I can’t overstate how much of an improvement they are over the stock bushes. Upgraded top mounts on the MK4 in my experience are an essential modification. Yes the top mount inserts are a huge improvement but the full polyurethane top mounts is another huge improvement again.
Camber Adjustable or Polyurethane?
Knowing what I know now, do I think camber adjustable top mounts would have been the better choice?
From what I see, people are fitting the camber mounts to track cars as consensus seems to be the stock geometry need more camber in corners.
I personally haven’t taken the 1.8T project on track but the car does occasionally get driven hard on the road
Tire Temps
I have had the chance to measure the tyre temperatures across the width of the tire during a spirited drive and I found the temperature across the tyre seems to be pretty even. If anything the inside of the front tyres may be getting very slightly warmer than the outside.
Again, these temps were measured with the poly top mounts which retain the original geometry.
The even temp across the tyres tells me that with the Michelin Pilot Sport 5s and H&R sport springs, the geometry is about perfect. The width of the tyre is getting worked evenly.
With this evidence, I personally haven’t see any sign that the car needs to run more camber or caster and therefore I’d say the camber adjustable top mounts are not necessary. At least in this case.
MK4 Top Mounts – Conclusion
In my experience, as detailed above, I think polyurethane top mounts are fine for normal and hard road use and for this reason I would choose them over camber adjustable top mounts for price and NVH.