Bumpsteer; How to rid my car of it?
 

I have myself a 1990 Miata, I lowered it with Koni Yellow's(middle clip) and Racing Beat Springs. I just aligned the car for zero toe all around. I have also depowered the rack a la FM's guide. The car has a pronounced amount of bumpsteer when compared to stock.

I have read that 94 Miata R tie rods sit lower in the knuckle and can help remove it and also some have talked about actually putting spacers under the rack to move it up and correct the tie rod angles.

Any other simpler ideas as to little things I can do to make it better?.

What wheels?

go to the high perch. what ever you do will change the toe so your cheapest option is going with raising the spring seat. if you get rack spacers (which i havent really seen done right in a long time0 your alignment will get jacked again.


93le/R tie rod ends do help a bit. but it isnt a night and day difference imo. still worth it though

I like it at the height it is at right now. If anything I want to lower the rear a touch more. I have access to an alignment rack whenever I need it so re aligning it is not an issue if I can fix my problems.

So you say a 93 LE has the same tie rods as the R? I am in Canada and was looking them up and did not find a listing for the R model, I will have to try the 93LE.

Current wheels on the car are BBS RM's 15x6.5 ET33 running 175/55/15 tires. I also have a set of Riken Turbo's 15x6 ET35 running 195/50/15 and there is no noticeable difference with either.

I am actually having a hard time finding a set of either 94R or 93LE outers. Does anyone know if there is an aftermarket part number from Moog or the like or are they basically a dealer only item?

So I take it that means they are dealer only and aftermarket just list the regular outers?

175 tires? This isn't KiaRio.com.

But seriously, if your ride height is exceedingly low the geometry will not be conducive to proper handling. If your current height has your tie rods increasing in elevation toward the ends, the best you can do is set your static toe outward slightly so that as the wheel travels upward it goes to zero before toeing inward at the top of its range of travel. If you are starting with a static toe-in it could be dangerous in bumps and braking. Excessive negative camber may aggravate the issue.

I get 175's for free from Mercedes tire pile with 70 percent tread left. Heck yeah I am going to run them. I have some Federal SS595's in a bigger size on order but they are not a normally stocked size and the last time they were ordered in an oddball size it took 5 months for them to come in. Stupid Canada.

https://www.miataturbo.net/attachmen...ine=1349712262

The car is not stupid low? I see others that look lower than me just browsing the forums. I daily the car and I don't enjoy scraping on everything all the time, so I was just curious what if anything others were doing so I could attempt to replicate it. I did notice an upward angle to the tie rods when I had it on the rack and this is part of the reason I am asking all these questions. If it were a Corolla like I am used to I would throw some RCA's on it and call it a day, but that is pretty hard with dual a arm.

You've named the two things that all non-Spec racers do to correct bumpsteer - '93LE/94R tie rod ends and steering rack shims. There's nothing else you can do AFAIK.

You're right, your car doesn't look excessively low, and your tires are not stretched as I had pictured since your wheels aren't too wide.

since you de-powered, your steering isint as dampend as before either which means CASTER has a HUGE effect on steering feel and the ability to resist road imperfections from messing with your input on the wheel. you mentioned toe, but left out your camber and caster readings, so I figured I'de throw that in...

Is shimming the rack something you have done on your own cars ? Is it a noticeable improvement ?

my 95 has a little bump steer Id like to remove. The spacers seem like a cheap easy thing I could try. What thickness of spacer do you see people using ?

I have a plan to try something a little different, and way cheaper. s13 outer tie rod ends.

https://www.miataturbo.net/suspensio...83/#post946594

The value of that thread is the knowledge that the Bump-steer "solutions" for S13 can be tried on Miatas as well (7 degrees taper).

Tapered shim inserts (just to get a mm or two lowered pivot point)?
Stupid and risky or just not worth the effort?
The cotter pin hole location doesn't bother me since I'm using nylocks.

Sorry to bring an old thread up. But has anyone used a rx7 fc tie rod and has good results? I am thinking of something like this
Mazda Rotary FC3S RX7 Adjustable Tie Rod End Kits New Product Sold as Pair | eBay

Like halfdemonpyro said; based on the little first-hand knowledge of your car, I'd think about getting a higher caster number.

I have a manual rack and daily drove it with ~5.5 degrees of caster and it was awesome. No bumpsteer

Now it's on 3.8 degrees and it feel a bit too light and has a touch of bumpsteer. I lowered the caster because I was going out of town for awhile and I was leaving the car with people who couldn't turn the wheel. >_<

ideas:

throw away the shitty konis.
throw away the shitty RB springs.

Dear :brain: , this thread is no longer about the OP, but a followup about using RX-7 parts on a Miata to assist in alleviating bump steer.

ideas:

use LE tie rods.