Polyurethane Strut Tower Bushings

[jkboyd]

Hi, I'm thinking of replacing my strut tower bushing with polyurethane. Are there any issues with running polyurethane, like binding etc.? Thanks!

[svono50]

That top mount is a pivot point for the front suspension, so increasing the stiffness would impact your suspension motion. Moving to poly material from the OEM 'onion head' rubber units would certainly be an increase, but I can't say how much impact that would really have as I moved from the onion head mounts to Maximum Motorsports adjustable mounts, which use a spherical bearing in them. The bearing mount allows smooth angular movement, but virtually zero vertical movement of the strut rod. Honestly I don't see that it would dramatically effect things using a poly bushing up there.

[jkboyd]

Thanks for the reply. I think most folks must go with CC plates because I didn't find much info on poly bushing. I found a threat on corral.net where someone brought up binding and possible strut shaft break and premature wear of the strut but I didn't understand how that's possible. I'll probably just wait and see if MM puts there CC plates on sale and go that route. How do you like the MM mounts?

[gbeaird]

Did they have actual shaft breakage, or they _thought_ there was that threat? While there is some movement there, unless you're running some drag racing suspension, where it goes full-range on launch, I'd doubt there's that much flex, certainly not on an SVO with good struts. Our car only has the factory onion-heads, though, since the car was run in F Stock by us.

And yes, I'd be interested in finding out how the MM parts worked out. Not sure they'd work with our STB, but there's always hope. :-)

[jkboyd]

I'm sure it was they thought there was a threat, because nobody said yeah my strut failed. I'd like to replace all of the bushings in my SVO but I don't believe the rubber onion head bushings are still available so I was looking at poly bushings. I've read there are issues with poly bushing binding when used in control arms etc. but I wasn't sure about poly strut tower bushings. I know there are issues in older Mustangs with running poly bushings versus rubber on the strut rods but that's a different animal, maybe that's where they got the idea. I don't know why I'm thinking about it now, I've got several projects ahead of replacing the bushings, like a new clutch and PIMP install. Lol

[svono50]

The onion head mounts are pretty much gone by now and the OEM ones left are likely aging out due to deterioration of the rubber components. The standard Fox 'sandwich' style mounts would be more serviceable, as the bushing in those is easily replaceable, but I believe they don't allow as much strut travel as the onion head units. I have never had the two styles side by side for measurements, but it seemed to be a pretty common comment when comparing the two.

The upper strut point has more motion when turning the wheels than in suspension articulation. As the spindle moves around the ball joint, the strut body swings around the coil spring, for reference, and the top of the strut pivots around the upper mount, which is where the motion comes from. This is why the 'better' caster/camber plates use a heavy duty spherical bearing to allow proper articulation of that upper point. The MM mount is strong enough to take the full weight of the front of the vehicle, as can be attributed by being able to run a coil over suspension setup...which I converted to this previous spring. What is nice about most CC plates is that the bearing is replaceable if they ever get worn out or damaged. As far as NVH, I can't say I noticed any difference when I originally installed mine about a decade ago, FWIW.

[jkboyd]

Thanks for the information! I'll likely go with the MM CC plates when the time comes. I have to keep an eye out for them on sale. Lol