cross member modification

[cj71z]

I wanted to see if anyone here has repositioned their control arms on the cross member to get rid of bumpsteer and roll center. A guy I talked to said he drilled the new hole 7/8in above and 1/4in out from the original. He seems to think that's correct, but doesn't really remember. I want to get some more opinions before I do this. This is pretty much a daily driver, but I enjoy driving it hard. What have you done and how does it work for you?

Thanks

Chris

[Black Beaut]

I've been looking in to this too. Seems like there isn't a definitive answer, each car is slightly different - great! 3/4" to 7/8" up gets you in the ball park but fine tuning is still required. Why can't life be easy?!!!

Plenty more info over at http://forums.hybridz.org/ if you can find it in searchland.

Cheers,

Rob

[240ZX]

I wanted to see if anyone here has repositioned their control arms on the cross member to get rid of bumpsteer and roll center. A guy I talked to said he drilled the new hole 7/8in above and 1/4in out from the original. He seems to think that's correct, but doesn't really remember. I want to get some more opinions before I do this. This is pretty much a daily driver, but I enjoy driving it hard. What have you done and how does it work for you?

Thanks

Chris

Robs input is good advise for sure. One thing to think about when moving the pivot point outward, you will be adding negative camber to the front suspension unless you have adjustable camber plates to compensate! Also, you will surely need to readjust your toe setting, as it will gain alot of toe-in. I've read a few articles that caution about moving the pivots too far out, as you may run out of threads (with stock steering links)when attempting to readjust the toe. It just so happens that I'm in the middle of doing the pivot relocation mod. In addition, I'm modding the LCA's with adjustable links and ball end bearing...plus, modding the TC rods in the same fashion. I also have adjustable camber plates, so I should have a very adjustable front suspension when I'm done with the effort. I have relocated my pivot points 0.75" up from stock and each side has been moved out 0.1875"

Question, have you been experiencing bumpsteer?

[cj71z]

I'm not looking for more negative camber so I wasn't going to move mine out. I haven't experienced bump-steer because it's a project and I haven't got to take it out for a good drive. 240ZX, how much did you lower your car? Mine is about 1.5 lower from the ST springs. I put in bump-steer spacers first, but now my tie-rod is rubbing the inside corner of my 14x6 rims. I figure I'll go with the cross member mod instead. I want to finish this so I can drive it :disappoin

[240ZX]

Chris, raising the LCA pivots as opposed to using the spacers is a good way to go to improve upon the bumpsteer issue, but it will not help your tie-rod end clearance issue. If you move the pivot point up only, there should be no toe issues...however I'd still have the alignment checked after the mod is completed. I'm not positive on the exact amount my 240 is lowered, but the top most part of my Z is 48" high and I have, at the front cross-member, 3 3/4" ground clearance. I certainly avoid speed bumps!!! I have coil-overs and 17" wheels, so I can run wide tires and I have good clearance for the tie-rod ends.

Talk at you later,

Tom

[cj71z]

Tom

I think that if I raise my pivot points the tie-rods should then be relatively similar to the stock position. I think the bump-steer spacers moved the tie-rods down too much resulting in my situation now...Once I'm done I'll definately get an alignment to correct anything going on. I read on Hybrid Z's that people seem to move them 13/16 to 15/16, seems like 7/8 is a good average.

Thanks

Chris

[auxilary]

keep in mind that redrilling your pivot points to fix bumpsteer varies with how much your car is lowered.

[ecp48]

Due to interference between the arm and the crossmember, 7/8 is the maximum with the stock arms. 3/4" or .75" is the norm and the suggested amount in the JTR manual. I've modified my crossmember and arms (rounding off the inner top end for clearance, but haven't had time to install them yet. Everything is sitting with new bushings. I did not move the mounting holes outboard. By lowering the car 1.5 inches, I did not feel I needed more negative camber in a "street Z".

Good luck!

[cj71z]

Thanks for all the input...Ecp it sounds like your going the same route as me, keep me posted on the results when you get it installed. I figured that the amount you move your mount depended on the amount you lowered your car. I've heard people talk about JTR, but never looked at it myself. I think I'll consult it before making my final decision.

Thanks

Chris