Hybrid Suspension compounds. Utter madness?

[Wishno87]

Thanks Darin. Im going to do that as well now.
You are a true man of genius!

[CorvallisBMW]

Don't forget! Post count in a forum = Real world experience.

so true... ;)

Josh, send Kencopperwheat a PM about the Urethane SF bushings. We just did his last summer, and he has definitely noticed an increase in NVH. I did mine with stock rubber and I have no complaints so far. Doing your TA's in urethane though is an excellent idea IMO. If you will wanted to reduce the flex if your SF bushings without adding NVH, you could try something like this:

http://www.r3vlimited.com/board/showthread.php?t=119954&highlight=subframe+idea

[Dillinger]

Don't forget! Post count in a forum = Real world experience.

[asubimmer]

I'm afraid you have it wrong.

The SF mounts work in an entirely different plane (front to back) from the differential mount (up and down) though they do have cross correlations they are small .

The chances of breaking anything increases with the hardness of the mounting bushings especially the differential mount which will break the tabs away from the body cross bracing or pull the brace from the belly pan when hard mounts are installed.

who are you mr 14 post count? I don't care if you wanna believe facts or not, its true. Mine broke w/ a new diff bushing and completely shot subframe bushings. I replaced both w/ delrin bushings and have been golden since.

Go out to the real world and get some real experience. :loco:

[Liam]

Very wrong. Yes the diff mount should be replaced too. I have had it happen to me personally and I have seen it happen to many others. It might not break the first day you do it but it will break.

I'm afraid you have it wrong.

The SF mounts work in an entirely different plane (front to back) from the differential mount (up and down) though they do have cross correlations they are small .

The chances of breaking anything increases with the hardness of the mounting bushings especially the differential mount which will break the tabs away from the body cross bracing or pull the brace from the belly pan when hard mounts are installed.

[Stephen]

both, he was responding to you I thought

I guessed so, but he wasnt clear.

To me, it seems i'd rather be safe than stuck with a broken diff mount

[asubimmer]

^ Is that in response to me or the OP?

both, he was responding to you I thought

[Stephen]

^ Is that in response to me or the OP?

[asubimmer]

The short answer is it will work fine and nothing is going to break.

Very wrong. Yes the diff mount should be replaced too. I have had it happen to me personally and I have seen it happen to many others. It might not break the first day you do it but it will break.

[Liam]

The short answer is it will work fine and nothing is going to break.

The long answer is that using harder bushing materials is going to transmit more road noise to the cabin (less so with the trailing arm bushings) and make the suspension less compliant.

None of this will affect the cowl shake on a C, that is caused by something else.

[Stephen]

So by this logic, when i install my green IE subframe bushings, which are urethane, i should also replace my diff mount (currently stock) with a comparable urethane bushing?

[smonkbmw]

/\ right and this is going into a car where the driver panics over any vibration, cowl shake etc. i was recommending all stock rubber to help combat this. advise?

[asubimmer]

Thanks for that. This is the kind of nitty gritty tech response i was looking for.

So then i should be doing rubber diff and subframe then urethane in the TAs.

Urethane is softer than delrin correct?

Yeah urethane is softer than delrin, but its not nearly as soft as rubber. Delrin is pretty much a solid mount. I would reccomend urethane for 98% of the ppl out there. Its much easier to install than the stock rubbers and they aren't too harsh for the street. The only reason to go harder would be for a dedicated track car imo.

[moatilliatta]

yes, id just do urethane everything, You wont notice to much more sound.

[Wishno87]

The trailing arms are different than the subframe/diff pair. The subframe and diff must be the same compound so that you don't break one or the other. The softer of those two would fail. Like if you had urethane subframe bushings and a rubber diff mount, then the diff mount would break off the rest of the diff. They work as a team you would say.

Now the trailing arm has nothing to do with them and any compund can be used between the two. Personally I have delrin subframe and diff mounts, and urethane trailing arm bushings. I would have used delrin TA bushings also but I had a set of urethane's around.

Thanks for that. This is the kind of nitty gritty tech response i was looking for.

So then i should be doing rubber diff and subframe then urethane in the TAs.

Urethane is softer than delrin correct?