Bump steer/Rack and pinion

[grandam75]

This is very interesting, I would really like to change the mounting points for the outer tie rods to get faster steering and fix bump steer. I was in a hurry when ordering parts for my vega. If I had done some research before I would probably have used AFX spindles with the bolt on steering arms. Have anyone compared measurements of the AFX spindles and S10?

Sorry I was unclear here.. I Was not refering to the super hitech AFX spindle. I just wonder if anyone compared a S10 spindle with a factory spindle from a A- F- or X body (firebird, chevelle etc..)? Would the ball joints fit, height etc?

[BadBowtie]

This is very interesting, I would really like to change the mounting points for the outer tie rods to get faster steering and fix bump steer. I was in a hurry when ordering parts for my vega. If I had done some research before I would probably have used AFX spindles with the bolt on steering arms. Have anyone compared measurements of the AFX spindles and S10?

Sorry I was unclear here.. I Was not refering to the super hitech AFX spindle. I just wonder if anyone compared a S10 spindle with a factory spindle from a A- F- or X body (firebird, chevelle etc..)? Would the ball joints fit, height etc?

If im not mistaken i beleive the balljoints are the same size for an s10 / 4th gen x-body / 2nd gen camaro... theres actually a whole list if you look up s10 ball joint sometimes under the part number you can get a list like junkyards have (i tried tonight but i came back empty handed ... however i found the site last night should have saved it...).. however the 4th gen x-body and the 2nd gen camaro are the same front steer spindles but taller than the s10's (something ive been looking into latley because of better geomety and brake size) ... but thats about all i know because i dont actually have the parts infront of me . Also i think they are the same for cars like a 76 malibu or a certain year of monte carlo as well.. its kind of frustrating trying to remember so much haha!

[NixVegaGT]

If im not mistaken i beleive the balljoints are the same size for an s10 / 4th gen x-body / 2nd gen camaro... theres actually a whole list if you look up s10 ball joint sometimes under the part number you can get a list like junkyards have…

Having just finished research on this very topic, I can corroborate that. Having a taller spindle is a good idea to counteract the built in camber gain GM designed. I don't know, however, if the ball joint locations are the same between them. For instance the h-body spindle vs. the S10 spindle: The lower BJ is mounted farther away from the spindle shaft than the h-body spindle by about 1/4". For some this causes excessive negative camber. If the XF spindles share this lower BJ mounting distance then it could be that greater height of the spindle would offset this issue because it would raise the rollcenter of the upper control arm out for increased positive camber. In effect fixing the location discrepancy.

That would be cool if it worked out that way. Anybody with experience or a spare FX spindle for dimensions, a post with that info would be greatly appreciated.

[Ishiftem]

Here is the deal with the rack dimensions. I have been running simulations on the computer, and the rack length is the LEAST important part of this equation for "zero" bump steer. The greatest factor by far is the inner and outer pivots. Leaving the height of the inner and outer pivots, the rack length is almost inconsequential. The difference between a 20" rack and a 23" inch is about 8/100 of an inch at 3 inches of dive. Lowering the outer pivot is the key. At it's stock height, with a 22 inch rack, the change in toe at 3 inches of dive is almost a Half inch. That's significant. Lowering it 1/2 inch brings toe change to .05 inches. That's nothing. So to make a long story short, Go with whatever rack in the 20 to 23 inch range works best for you(budget,availability, etc.) Install it so the the pivot heights are the same as stock. Then go get a bump steer kit from Sphon or where ever, and lower the outer pivot 1/2 inch. This will get you so close it will scare you. Make final adjustments on the car with the bump steer kit to achieve zero bump steer. This is with stock vega spindles. That's it folks, nothing to it. Figuring different spindle heights or adjusting ackerman is much more complicated. I'll need more time on that.


P.S. You could even go shorter on the rack. I wouldn't go longer tho. Also the stock crap if your interested toes out .43 inches at three inches of dive. Way to go GM

[NixVegaGT]

LOL on the P.S., hell yeah. Thanks man! I'm looking forward to the next installment.

[waybad]

Thank you very much for all your hard work on this matter!! It's nice to have smart people on this site ,,, and thanks for a great site!!!!!!

[Astre-mutt]

Dan, I've been looking at your findings on the suspension program. You keep mentioning "dive", but what about "rise. Also does the stock suspension have 3" of dive? I thought there was only about 4" of travel (at the shocks) total.

[Ishiftem]

I used 3 inches of dive because that would be an extreme. The program does not use droop. I wish it did, but what are you going to do. The thinking is that if a race car went into droop, it would probably be heading into the wall anyway. I don't know off hand what the travel is. I don't have a spring in my car so I could put the koni shock I have back in and see what it is. For my own purposes though, I really don't care. I use 1,2, and three inches of dive along with 1,2,and 3 degrees of roll and numerous combinations of those together. With less dive calculating bump steer, it only got better which stands to reason less travel wold have less of an effect.

[Ishiftem]

just went into the garage. The suspension will travel up from the stock ride height about 2.75 inches before contacting the rubber snubber. Say that real fast.

[grandam75]

I found some interesting reading on how to mount the steering rack etc on woodwards webpage:
http://www.woodwardsteering.com/images/cat05%20pdf%2064-79.pdf

[Kenova]

I found some interesting reading on how to mount the steering rack etc on woodwards webpage:
http://www.woodwardsteering.com/images/cat05%20pdf%2064-79.pdf

Good reading. I may actually be starting to understand it all.

Ken

[NixVegaGT]

THat is interesting. I may adjust my plans a bit based on this. Thanks for the resource.

[waybad]

well got my rack today,, and guess what,, it's 25" at the pivot points I can't catch a break with this car

[Ishiftem]

Narrower would be better, but let me run it through the program and see what happens. Give me a day or two. Might not be as bad as you think. Or it might be.

[waybad]

thank you don't be any hurry,, I'm sure it's way to long,,
that's the first time I can say that and not be lying