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I am having a problem with terrible bump steer, anything stand out in this picture that should be corrected to you guys? Thanks Rich

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MK Indy R1
SuperFormance S1
SOLD: Brunton Super Stalker
SOLD: Locost-Turbo 280HP
SOLD: Locost CBR1000 powered autocrosser
SOLD: Locost R1 powered

It appears the rack width (inner ball center to inner ball center) is too wide. In general the balls should fall on a line between the UCAP and the LCAP or close to it. Outer tie rod position has an effect also.

Is this the one that used to have the electric steering?

Still have the vee?

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
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360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

From Tanner's book:

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Build log http://www.locostusa.com/forums/viewtopic.php?t=16510

What are you calling bumpsteer? Hard to drive? Wandering over bumps?
I agree with MiataV8 that the steering rack may be too long.
Can you take a picture looking down on the control arms for us to get a better relationship between all 3 ball joints?
It appears from the picture that you may be using a rear steer spindle in a front steer application. This is the reason I asked fro a picture. If so the Ackermann angles way off.
If the rack is too long (tie rods too short) with your front steer (steering arm to the front), the tires will toe in under bump and droop. The outer tie rod ball joint may be a little high (or rack too low) which could cause a tire that starts to toe out on initial bump then starts toeing in with more bump.

Here is a pro laser alignment set up for bumpsteer. Easy to make one with simple pieces.

https://advancedracing.com/product/lase ... eer-gauge/

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My build log viewtopic.php?f=36&t=10658&start=0 NOW NAMED =The Wycked 7

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I actually replaced the tie-rod ends today as the original builder had those washers in there ( see original post) that weren't doing anything other than tearing the boot and binding up the steering. I am wondering if it the angle of the tie-rods is my issue because it yanks the wheel out of my hand on bumps on the road- I believe at droop. I jacked up the car on my lift and as it raises( simulating droop) the tire on that side starts to turn outward. The car btw is a Stalker with the standard S10 front suspension...

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MK Indy R1
SuperFormance S1
SOLD: Brunton Super Stalker
SOLD: Locost-Turbo 280HP
SOLD: Locost CBR1000 powered autocrosser
SOLD: Locost R1 powered

It looks like the tie rod would run out of clearance in droop. I don't know why there would be any washers if it fit the quicksteer plate properly.
It appears the rack is too high for the plate mount. You could mod the plate to locate the tie rod higher (I'm guessing that is why someone added washers-not good) by welding a new boss above the plate so the tie rod has more droop travel, adapt to universal sphericals which can be shimmed, or heat and twist the plate end to put the tie rod ballstud perpendicular to the tie rod.

I see you have some positive ackerman in the overhead view which is good.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

Just looking at the photo's, you need to lower the steering rack a good inch. How is the rack attached. Can you remove shims from under the rack? Could the mounting blocks be up-side down? To be able to hone in the bump steer, you need to be able to make adjustments as fine .02 to .03"
The first thing is make a simple bump steer gauge. It's the only way to get close to zero bump steer.
Davew

Well,thanks for all the responses guys, I really appreciate it. I think I will start with converting over to spherical rod ends,that will give me more adjustment up and down-hopefully that tames it,if not, then I will look into moving the rack as a second option.

_________________
MK Indy R1
SuperFormance S1
SOLD: Brunton Super Stalker
SOLD: Locost-Turbo 280HP
SOLD: Locost CBR1000 powered autocrosser
SOLD: Locost R1 powered

There's also the issue of what's a good target to shoot for in reality.

Somewhere along my Locost journey, I found one definition of acceptable for dive, which was, "at 3" of dive, maximum toe out of 3/4" for both wheels." From that I took 1/2 x 3/4" = 3/8" toe out per wheel, maximum. I'm not saying that's a universal rule of thumb, but rather, if that's not it, what are good targets for both dive and bump?

Another question I have is, "would there be different targets for a street car versus a track car?"

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

Bump steer is best kept to a minimum that you can achieve, measure and adjust. Your steering axis appears to be at the edge of your tire contact area (inside edge) which may be your real problem as far as reaction at the steering wheel to bumps and unsymetrical wheel loadings. The closer the steering axis is to the contact patch center the less it is affected by unsymmetrical wheel loadings (may be a loss of road feel if perfectly aligned with the contact patch center). Just my thoughts, Ackerman looks in the right direction, a change in wheel offset (or removal of wheel spacers if present) might improve the situation.

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Perhaps it is just my inexperience with steering geometry changes at the extremes, but 3/8" of toe out per side seems like A LOT! I realize that is at full bump or droop, but still.

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JB

Now that I look at the pics again the scrub radius does appear to be quite large. And I could be wrong about this but iirc the S10 spindles have a little bit of reverse ackerman in order for the tie rod end to clear the inner lip of the wheel barrel. Someone please correct me if I am wrong.

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JB

One small detail - the point between C and D that represent the tie-rod end should be on the line between the balljoints. If ackermann has the actual joint in or out from that line then it needs to live on the line projected between the tie-rod joints.

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-Andrew
Build Log
Youtube

Note that the spindles are not 100% S10. The steering arm appears to have been cut off and a "quick steer" (my words) arm bolted on somehow. Probably best to work thru this particular issue with the Stalker group if you can. You will likely get a more focused answer from those who have been there, done that. That said, I hate directing a person to another site. We have some very good brains here.

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Chuck.

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I was going to mention the scrub radius too You can band-aid around it with more caster and/or power steering but with a wide tire on a light car, it will kick around a lot. My Legends car was the same - you could see the lower ball joint from the front of the car. I bought the largest backspace wheels i could find, then lengthened the suspension to keep the width the same

Building a simple bumpsteer gauge is easy. 3 small pieces of MDF, a hinge , a 1/4 steel rod, a few screws and a $10 dial indicator from Harbor Fright is all you need. A small amount of bumpsteer can make a big difference. I have my car at 0.020" at 2 inches of bump (then it goes a little haywire) - note that caster angle effects bumpsteer. Need to adjust bumpsteer when changing caster. Small light cars feel a lot better with low caster, IMHO, as long as the rest of the geometry is good.