Will shortening tie rods 3/4" cause bump steer?

I am narrowing an IFS cross member 1.5" Total. I am looking at the tie rod ends and there is right at 3/4" of threads left on the tie rod behind the jamb nut.

Rather than narrow the rack for 1.5", My thought is to just tighten up the tie rods on each side 3/4". Will this be enough to cause bump steer???

 

Not sure it will cause bumpsteer, but running them down to where there is no more adjustment may cause some concern. Especially if you need just a bit more to get into spec....and that could cause bumpsteer....(if you don't have proper toe adjustment)

 

Yes that will cause Bump Steer. You are narrowing the crossmember which means you are moving the pivot points inward. You MUST move the pivot points of the tie rods at the rack and equal amount to avoid Bump Steer.

 

hotroddon is right, this will induce bumpsteer. In order to get the geometry correct you need to layout the positioning of the upper a-arm's pivot point (this is the center of the bushing located near the frame), the same for the lower a-arm pivot point and the location of the rack. Draw a line from the upper a-arm pivot point to the lower a-arm pivot point. The pont where the center line of the rack intersects the line will be the correct pivot for the rack.
You can take this pont and re***ociate the upper/lower a-arm pivot points and your front suspension geometry will be correct.

Cheers!
Mickm

 

had a buddy who did this with a Studebaker. bought a MII setup, narrowed it 4" +- and didn't listen to me when I told him he needed to narrow the rack as well sinc e he was the ace fabricater with all the cool tools.

it was so bad you couldn't even drive it at all. so he heated and bent the tie rods and beat it into submission. it still wasn't right but he gave it to his customer anyway. went out of business soon after.

 

I did a 2" narrow on a Must II on my Rambler American sed delivery- without narrowing the rack and it drove fine...had it over a 100 a couple p***es -also I drove it from Elmer Missouri to Torronto Canada without any trouble so it must not have been a real problem....
I think moving the rack up or down from its factory location would cause some problems though....

 

I can run a die down them 1/4" or so to give me a little more room for the jamb nut. I know that moving the pivot points will cause bump steer, especially drastic changes.

I am just not sure that 3/4" is going to cause it, or enough of it to be a concern, have any of you guys tried or seen this from personal experience???

I plan to shorten the ends of the rack piston and leave the housing alone if I can, I will resort to tie rods as a last resort. Mainly for the fact I would like to leave the rack as stock as possible in case I need to replace it down the road.

 

Thanks choprods, that's the response I was looking for.

I mean worst case scenario is I try it, and it ****s and then I modify the rack. But I'm holding that out as a last resort.

 

I run a 2" wider Mustang II kit. The instructions told me to use Fairmont tie rod ends (because they are one inch longer than the Mustang tie rods). Technically my lower control arms and my tie rod arms now swing on a slightly different arc ... the inner pivot point of the arms was moved out due to the widening of the crossmember but the rack was not widened too, it was just lengthened through the use of different tie rods.

End result, absolutely no noticable bumpsteer or any other kind of steering issues. Technically speaking, my setup is not correct ... just don't tell my car that, it thinks it's fine.

I'm thinking the reason my car drives well is this, even though it is not technically (or geometrically perfectly correct in theory) the amount of widening is not enough to cause any issues. I do not know if the same applies to narrowing though. My Mustang II kit was purchased from Horton Hotrods here in Ontario Canada. The owner of Hortons (and builder/designer of my kit) at the time of purchase is on this site under the name "Welder Series". I would suggest you try a PM to him (Paul Horton) for an answer to your question. Hortons Hot Rods is now under new ownership, Paul owns Welder Series now ... a hot rod component ch***is component company ... nice guy too.

One other thought ... the Mustang rack tie rod arm is actually slightly larger in diameter where it is threaded. I would NOT recommend trying to extend the threaded area up the tie rod arm shaft, there is just not enough metal for a safe thread.

 

Yes

 

I installed a Heights IFS with narrowed a arms in a 39 ford.
They gave me with kit a standard rack unasteer.They say to cut off 5/8" each end.I centered rack with equal turns both side,lined up and cut off what was to long.So I would cut the ends before the rack.
I don,t have any bump steer or any other problems with mine.

 

woodward has the best tech articals on bump steer

read this stuff click on basic tech incon

http://woodwardsteering.com/index.php?option=com_content&view=article&id=682&Itemid=586

http://woodwardsteering.com/

 

I think it would depend on what width you are working with.I think say Speedway list 3 different sizes.If you had a wide one now you could be ok.

 

Like borntolose I widened a MII about 2" for my '62 Studebaker truck by using Fairmount tie rod ends. I had no problem with the suspension or handling. Brakes were a different story.

 

Good reading on bump steer -

http://www.longacreracing.com/articles/art.asp?ARTID=13

 

I feel like deja vu, all over again. This is high tech measuring right here.
http://www.youtube.com/watch?v=o-JfwRyE_q0

 

Steve- they just don't listen or believe do they?

 

Some do, some don't.

Some want an echo chamber and don't really care what the correct answer is, they just want to be verified. Such is life.

8)

 

No kidding. I find on here if someone plans to do something and 20 guys say don't do it and only one say's "go ahead, it will be fine" that's all they need. They go ahead and do it, especially if doing it right requiers more work/ money!

 

you can lead a horse to water .....

 

OK, one more question, this isn't to argue but more of a why??? Wouldnt/doesn't every car HAVE to experience some bump steer when turning?

Based on the drawing above the inner tierods and pivots have to be planar, and the outers have to be planar. When turning the outer pivots all stay planar. The inner pivots are fixed and the tie rod would either be short of the line or past the line depending on which way the wheel was turned.

So is there always bumpsteer there and its just too minimal to notice?

 

good!

 

Every car DOES experience m***ive bump steer when turning. The best you can hope for (and should set up for) is that it doesn't try to turn itself when you are going straight...

 

x2!

 

THE man, THE word, THE end....

 

Nope. In a correctly designed suspension, everything is going to work together on the same plain. It's all designed to travel in a certain range too.


This idea of "a little bit of missalignment is okay" escapes me entirely. It might not show as a problem going straight down the road, (although what you are contmplting probably will) but when you comfortable with it and decide to push just a bit harder than usual, that's when things go to hell in a hurry. I might not explain this correctly, and I'm sure ElPolacko or HotrodDon can, but it has to do with slip angles effecting traction. The further you are off the straight and narrow with a tire, the more it is reduced in traction to the road. Going straight it can give a floaty, disconected feeling that isn't comfortable. In a turn though, when a tires grip is already reduced by the basic physics of the event, reducing it further by slipping that tire more can be dissasterous. Terminal understeer is one effect I can think of.

I can't tell you how many times I have talked with people that tell me they're hot rod is great and rides and drives good, but later admit that they don't like to take it on trips or drive it much because it feels disconected or floaty... Then end that statement with "but that's just the way they are..." It doesn't have to be that way. Do it right, do it once.

 

I fooled around with a car I was building for a guy, for over 6 months before I finally gave in and had someone check it out and fix it right...it was bumpsteer. Now it had never even occurred to me, I bought a M2 kit from a reputable guy, and installed it correctly. I did alignments over and over, measured the frame for starightness, the rear for straightness, pinion angle, raised, lowered the front end, did everything imaginable.
Finally gave up and sent it over to Rob Ida (the hi-tech rod and Willys builder) and he found it right off the bat. Fixed it with some machined tie rod ends, with spacers to dial it it, between the tie rod end and steering arm. Fixed it perfectly!
Now, what am I saying? Listen to the experts! Bump steer is a *****...it even occurs with pre-manufactured kits! If you know it's going to be wrong, FIX IT! It can make the car practically un-driveable.

 

I molded a '68 camaro front clip to the frame of my '54 Chevy panel. Upon doing so I narrowed the clip 3.25" for a narrower width to match the original panel specks. Afterwards I realized this wasn't necessary. However the problem I'm having, much like tlmartin84, is a rack that isn't narrow enough. I found a rear steer power rack out of a '00 grand am & when I installed it & ran my suspension through its travel, I ended up with horrible bump steer. This is due to my a-arm & inner tie rod pivoting on different arcs. I was told to take my rack apart & trim everything down to narrow it, but idk if it will be enough. The camaro a-arms mount @ an angle unlike a MII that seems to be more parellel. From shortening the clip, it puts the rear most lower a-arm pushings @ 15.25" & the front @ 21" & currently the inner tie rods on my rack are 22.5" apart. So do I shorten the rack by 6" or use front steer, though I was told front steer won't work with my stock spindles?

 

OK =OK,
you CAN lead a horse to water......
and then you will always have a horses *** show up there too......
I said what I did on my'60 Rambler American .-narrowed the crossmember but not the rack= 2 inches.....
I adjusted the tierods in to correct toe in with no re threading or cutting-It worked perfectly and I am as good a judge of that as anyone else here is......

also they make a jamb nut half as wide/thick, as the stock Must II jamb nut was for exposing added thread s available......

 

I have a friend doing a scale solid works model (CAD) of this front end for me just for kicks, gonna test it in the stock setup and with some modifications to it. If he can get it done I'll let you guys know.

Like I said earlier I am not arguing with the guys saying its fine, nor the guys saying its wrong. From a geo/trigonometry standpoint I know it is wrong. But at the same time there have to different scenarios where there is wiggle room. I'm just a nerd and wanna understand how it works, guess thats why i'm an engineer. For every action there is an opposite and equal reaction...........