Yikes! prob. w/urethane bushings and petroleum-based grease?

[Grubester]

The FFR Assy. Man. mentions urethane bushings for the mounts for the differential on IRS units, but are the bushings that come preinstalled in the control arms also urethane?
This is a big deal because after talking with Lucas Oil (they make the petroleum-based grease I used: Red 'n Tacky) they said it is not compatible with urethane materials.
Further, I spoke with a tech guy at Thorbros, (Francisco, IN) and he said that petroleum grease degrades urethane over time. Thorbros makes urethane bushing assemblies.

(when I asked Thorbros about design criteria regarding length of sleeve inside the bushing assemblies, he said their design rule is that the sleeve is 0.005" to 0.010" shorter than the stacked length of the two bushings. This gives a light-crush on the bushing assembly once the bolts are fully torqued [I'm pre-greasing, following w/grease gun]. I asked because when I get anywhere near the torque value on the IRS upper control arms they are effective locked up: there are several remediation paths possible, but that's a different post.)

Anyway, I may need to disassemble front and rear suspension and clean/re-grease the bushings... we'll see.

Factory Five Racing:
1) please comment on the material type used for control arm bushings,
2) please comment on grease-compatibility issues I've mentioned,
3) page 16 of "Req'd Supp." doesn't mention anything about grease type

Thanks all!

[burchfieldb]

The FFR Assy. Man. mentions urethane bushings for the mounts for the differential on IRS units, but are the bushings that come preinstalled in the control arms also urethane?
This is a big deal because after talking with Lucas Oil (they make the petroleum-based grease I used: Red 'n Tacky) they said it is not compatible with urethane materials.
Further, I spoke with a tech guy at Thorbros, (Francisco, IN) and he said that petroleum grease degrades urethane over time. Thorbros makes urethane bushing assemblies.

(when I asked Thorbros about design criteria regarding length of sleeve inside the bushing assemblies, he said their design rule is that the sleeve is 0.005" to 0.010" shorter than the stacked length of the two bushings. This gives a light-crush on the bushing assembly once the bolts are fully torqued [I'm pre-greasing, following w/grease gun]. I asked because when I get anywhere near the torque value on the IRS upper control arms they are effective locked up: there are several remediation paths possible, but that's a different post.)

Anyway, I may need to disassemble front and rear suspension and clean/re-grease the bushings... we'll see.

Factory Five Racing:
1) please comment on the material type used for control arm bushings,
2) please comment on grease-compatibility issues I've mentioned,
3) page 16 of "Req'd Supp." doesn't mention anything about grease type

Thanks all!

Dan Golub from FFR said that they should be polyurethane for the control arm bushings on the coupe. I picked up some of this Super Lube at my local hardware store.

https://www.peaksuspension.com/product/super-lube-synthetic-grease-for-poly-bushings/

[Grubester]

Thanks! The guy at Thorbros also said to use Super Lube, a synthetic. Ugh! It means I need to disassemble all the control arms and clean and re-grease.
The FFR manual says nothing about this. I think it's a big oversight. This issue needs visibility. Again, ugh.

[JimStone]

I used Red'n Tacky...

How big of a deal is this? I REALLY don't want to take everything apart

[Grubester]

I know. The big question is... how big a deal is it??? We don't want to get caught up in "don't let the perfect, be the enemy of the good."
Before I disassemble and clean (starting tomorrow...?) I'd like to hear from more of those that can offer an informed opinion.
From what I understand, the petroleum greases cause a degradation of the polyurethane material. (a classic materials compatibility issue...?)

[rustyrim]

one member here has over 600,000 miles on his cobra , it would be a concern for him. If it is a concern for you you can buy some extra grease and flush the incorrect grease out by putting new correct in.

[Jeff Kleiner]

I recently changed all of my poly bushings to spherical bearings. They had been lubed regularly for 17 years and 30k miles with regular petroleum grease and looked new when I pulled them out.

Jeff

[CraigS]

No idea if it's available but perhaps a synthetic grease in grey or black to flush out the old red grease.

[rich grsc]

Typical over think.
You posted the same thing twice?

[Grubester]

Yes, posted twice by mistake -- the first hadn't shown up and I assumed I had ham-fisted it somehow.
I think "over-think" doesn't get to my concern. It looks like a fundamental material incompatibility and I was looking for experienced/empirical commentary AND engineering technical commentary.
For instance, Jeff Kleiner has related extensive first-hand experience that would indicate it is not a high priority -- that would be good!
I'd also like to hear (maybe other new builders, too) the technical side. For instance, an example might be: "tests show that it has a very weak interaction and though not a preferred combination, it isn't significant enough to remediate"... or some such.
I did say in my initial post: Don't let 'perfect' be the enemy of the good. As builders, we make MANY judgement calls along the way, some dictated by our own experience, some with the help of "the community". I'm only asking for additional insight on this one.

[JimStone]

Thanks for the input guys. Sounds like, real-world, not a big deal.

But I now have a bug in my ear, so I'll probably flush out the red grease with synthetic