Dropping Rear Subframe

[FishMan]

They are legal… Thanks for the feedback!

[Ranger]

Last Spring I asked Chuck Baader about subframe bushings because eventually I’m going to replace my subframe and have welded toe/camber adjusters installed. Chuck said do aluminum subframe bushings. Apparently the philosophy in those classes that allow metal bushings is that drivetrain and frame movement is bad and one should attempt to control it wherever they can.

Subject change. Is an aluminum diff bushing legal? I’m thinking no.

[kgobey]

My instinct was to agree with you… But:

9.3.8.8. Suspension bushing material replacement is permitted.

9.3.8.8.1. A single set screw per suspension bushing may be used to inhibit bushing rotation. The set screw must serve no other function. The bushing housing may be modified to accommodate the set screw.

There are 2 other references to Suspension Bushings, but none of the references rule in or out any particular material.

That being said - Jeff Ireland really knows his stuff, regardless.

Ireland Engineering race urethane subframe mounts are made of special very stiff urethane. This material is similar to Delrin except much tougher. We now use these instead of solid aluminum mounts. Dramatically reduces compliance for more precise handling, and are very easy to install. Can be used on the street but will increase harshness and noise.

I am picking the Ireland Urethane most likely.

[Steve_D]

Ranger wrote:

[quote]Subject change. Is an aluminum diff bushing legal? I’m thinking no.[/quote]I would argue that the diff bushing is a suspension bushing just like the subframe bushings. The differential case acts as the subframe’s triangulated third attachment point to the chassis.

That being said, I don’t think there is anything to be gained by using aluminum suspension bushings. When you’re eating spaghetti, does it matter how stiff the fork is?:huh:

[turbo329is]

I thought people stopped using aluminum for bushings when delrin was invented. Aluminum wears pretty horribly and isn’t used for a bushing or bearing on anything but racecars. If you want metal bushings I think It would be better to have some made out of brass or a nickel alloy made for making bearings. Its not like you want so save weight there anyway. I have had bushings made at my local machine shop before.

[Ranger]

turbo329is wrote:

Aluminum wears pretty horribly and isn’t used for a bushing or bearing on anything but racecars.

That’s confusing.