I'm doing a LS1 and 6 speed swap on a 87 Formula. I've installed Spohn mounts and crossmember. The K-members done and back in and the compressors installed. The idler arm hits on the compressor clutch and even if I shim the mounts it's gonna be tight. Maybe too tight. Noises from hitting on the body are not gonna be acceptable. Dropping the angle of the idler arm down closer to the level of the outter tie rod ends is going to effect the way this car steers. Any effect on the steering is really out of the question also. Would the Spohn K-member fix this issue ? any other Ideas ? thanks

 

I had the same problem, but my suspenion was unloaded. the car was on jack stands. When I put the car on the ground it didn't hit.

 

I've also read that alot have had to notch the idler arm for it to clear.

 

Why would dropping the idler affect steering? I dropped mine as low as it would go and had to shave the bolt down after bolting up with a zip cut to clear but no steering issues at all. Its close but it works fine for me

 

Thanks for the response. Woulda responded earlier, was vacationing. I'm hoping that setting it on the ground with the wheels and control arms in place will give me a bit of clearance but I doubt it. Lowering the Idler arm is not what I want to do but If others have done it with no problem then I'll do what I gotta do. I have heard from our front end guys that lowering the idler could cause the steering wheel to jump like it crawls over something. That is if the idler arm is lower than the outter tie rod ends. I think I need to get through this part before I go on because I'm sure I'll find myself needing to get through with another step. Even though the driveability and electrical is what I do for a living, the change over here is something that I am concerned about. Specifically the PCM adaptability.

 

I'm not sure I follow you here. Can you elaborate? Are you referring to bump steer?

 

That's the word I was looking for yes...

 

I never considered any bump steer affects from the idler but I'll check it out when i swap my struts soon. I only dropped mine about 3/4" as thats all it would go but I seriously doubt that little drop would cause problems with bump steer. If I find anything odd I'll post up about it

 

Idler arm needs to be at same height as the pitman arm in order to maintain proper steering geometry.

 

I've been told that if the Idler-pitman does not have a drop angle down to the steering knuckles then bump steer will occur. I've been a tech/manager-trouble shooter and the guy other shops call when they have problems for over 30 years and I don't know that I've even experianced bump steer. Since this isn't my ride, I'm trying to make sure that I do this right the first time out.

Thanks
Rick

 

Yes you want a drop angle to the steering knuckles but you want to make sure it's the same angle on both sides. The height of the pitman arm and idler arm determine this angle. The height of the pitman arm is not adjustable although it may change slightly with a different box. That's why the idler arm is adjusted to it.

If you examine the geometry of the system you'll see that there's ALWAYS some bump steer-as either wheel moves up or down the tie-rods move in an arc and the horizontal distance from the tie-rod mount (centerlink) to the steering knuckle changes slightly. Maintaining the slightly downward angle reduces this effect and makes it the 'good' type of bumpsteer.

That's why lowered cars that don't use spindles with adjusted knuckle heights experience more bumpsteer. They've altered (reduced) the drop angle from the tie-rod mount (centerlink) to the knuckle.