inverted tie rod end or Roll centre adjuster?

[Sydneykid]

So given that the Mugen SS lowers my car by 1.4 inches (35mm), a modification of some sort is needed for my tie rods?

Nope, not the tie rods, the steering arms. You need a set with the tie rod end taper downwards, instead of upwards like the standard steering arms.

The bump steer on our cars is also a function of the very small caster angles too, isn't it?

Nope, caster realy has nothing to do with bump steer. Bump steer is changes in the toe settings as the suspension moves up and down. For example you set the car at zero toe at normal ride height and it toes out 5 mm when the suspension compresses 50 mm. Then it toes in 5 mm when the suspension extends 25 mm. So it drives down the road toeing in and out every time it hits a bump, making the car steer all over the place. Hence the term "bump steer".

It's even worse for a race car where the constantly changing toe angle disrupts the tyre's contact patch and it loses traction. So the car won't hold a line through a corner, it steers and slides all over the place. Very slow and, maybe more importantly, very unsettling for the driver.


Cheers
Gary

[chargeR]

Good info Gary. I have a couple of questions for you that hopefully aren't too off the topic of the thread.

I am also using the Mugen lower brackets and I was forced to shorten my tie rods in order to get zero toe or any toe out, how much more adjustment do you have on your tie rods? I am surprised you got away without having to modify the tie rods.

Have you measured the bump steer with the Mugen brackets in place? I am just curious. I run my car moderately low (330mm vertically from centre of the wheel to my hammered out guards) and the bump steer characteristics of the inverted tie rods when using the Mugen brackets has always interested me, although not enough to do it myself .

Thanks.

[Sydneykid]

Good info Gary. I have a couple of questions for you that hopefully aren't too off the topic of the thread.

I don't think they are of topic at all. In suspension pretty much everything affects everything else, so there's not a lot of off topic anyway.

I am also using the Mugen lower brackets and I was forced to shorten my tie rods in order to get zero toe or any toe out, how much more adjustment do you have on your tie rods? I am surprised you got away without having to modify the tie rods.

By "shorten the tie rods" do you mean cut ands re thread them or simply adjust their length by the thread provided?

When you lower a DC5 without changing the steering arms you have to wind out the tie rods to get the static toe back where it belongs. On the other hand, when you lower a DC5 and change the steering arms at the same time you don't have have to wind out the tie rods to get the static toe back where it belongs, it's pretty much right where it is.

Maybe what you are describing is simply puting the steering arms' length back close to where they were before you lowered it.

Have you measured the bump steer with the Mugen brackets in place? I am just curious. I run my car moderately low (330mm vertically from centre of the wheel to my hammered out guards) and the bump steer characteristics of the inverted tie rods when using the Mugen brackets has always interested me, although not enough to do it myself

Of course, you can't have bump steer in a race car, so the target is always zero. In a production based car we very rarely achieve zero through the whole range of travel suspension, so the compromise is zero within the most commonly used travel. That 50 mm of bump and 25 mm of rebound I talked about in the previous post.

We shouldn't ignore the rear bump steer, it's just as important for handling, you just don't feel it as much through the steering.


Cheers
Gary

[chargeR]

By "shorten the tie rods" do you mean cut ands re thread them or simply adjust their length by the thread provided?

When you lower a DC5 without changing the steering arms you have to wind out the tie rods to get the static toe back where it belongs. On the other hand, when you lower a DC5 and change the steering arms at the same time you don't have have to wind out the tie rods to get the static toe back where it belongs, it's pretty much right where it is.

Maybe what you are describing is simply puting the steering arms' length back close to where they were before you lowered it.



Of course, you can't have bump steer in a race car, so the target is always zero. In a production based car we very rarely achieve zero through the whole range of travel suspension, so the compromise is zero within the most commonly used travel. That 50 mm of bump and 25 mm of rebound I talked about in the previous post.

We shouldn't ignore the rear bump steer, it's just as important for handling, you just don't feel it as much through the steering.


Cheers
Gary

Yep I had to cut and re-thread my tie rods as the tie rod ends were bottomed out on the tie rod and I still had toe in . The other person I know that has used the Mugen brackets also had to do the same. What dampers are you using if you don't mind sharing?

So you are saying that those numbers posted above are the bump steer numbers that you have measured or they were around that?

[Sydneykid]

[QUOTE]

Yep I had to cut and re-thread my tie rods as the tie rod ends were bottomed out on the tie rod and I still had toe in . The other person I know that has used the Mugen brackets also had to do the same.

When we flipped the tie rods ends over at the lower ride height the steering arms ended up back in the same position as they were before we lowered it. So I'm not sure why you would have to shorten the steering arms.

What dampers are you using if you don't mind sharing?

Tein N1's in one of the cars, that I have changed the springs rates and changed the valving 5 times. The off shelf rates (spring and damper) were rediculous and the adjustments far too fine, they did basically nothing. The other car has MCA's (nee Proflex), they were spot on out of the box and I all I have done is fine tuning of the bump and rebound adjustments for each track. The car with the MCA's is faster and gentler on its tires, despite my best efforts with the Teins.

So you are saying that those numbers posted above are the bump steer numbers that you have measured or they were around that?

Around that, the two cars were slightly different.

Cheers
Gary

[SHRUKA]

Bringing this post back alive as I need some assistance.

I just got J's RCA installed onto my EP3R and so far it feels okay but there is still whacky steering going on (steering wheel leaning to the left, and sometimes pulling heavily on some parts of the road) but that's maybe because I haven't got a wheel alignment after the installation.

If the wheel alignment doesnt fully correct my steering/bumpsteer, what would be my next step?

[androo]

Get the alignment first...

[DreadAngel]

Alignment should fix your issues...................

[SHRUKA]

So I got my J's Racing RCA installed + wheel alignment.

Running -
F -1.25 camber, zero toe
R -2.8, -2.3 camber, +1.0 toe

Yet I still get this heavy pull on my steering on slanted roads and everytime I hit vtec on gear 2 the steering goes crazy left-right.
I've been trying to diagnose this problem for quite some time.
Though the J's Racing RCA does make a difference on bump steer which is good but doesn't fix this steering problem.

Do I need inverted tie rod ends? OR even Tegiwa Steering Rack Raisers?

[amant02]

Hey Post a pic of your wheel alignment read/print out.

I think you may need to go to a better shop.

I have been thru the bump steer/ Wheel pulling to one side issue on my dc5, after all the researching/spending ..... You just need to go to a shop that know their shit is all.

[SHRUKA]

Hey Post a pic of your wheel alignment read/print out.

I think you may need to go to a better shop.

I have been thru the bump steer/ Wheel pulling to one side issue on my dc5, after all the researching/spending ..... You just need to go to a shop that know their shit is all.

Here is the print out of my current specs.

http://imgur.com/Lzm3Sx7

[SHRUKA]

BUMP - Need some professional assistance.