Bump steer problem in DC5R

[Lemmiwinks]

Got a bit of bump steer happening in my car and I'm not too sure how to resolve it! Thought I might ask the experts on here

Just got back from a drive to the country on bumpy roads and I got a fair bit of bump steer which is concerning.I recently fitted some new wheels to my DC5R and supporting mods to make them fit.

Parts I have fitted:
BC BR coilovers
Todds shortened tie rods
18 x 9.5" +22 rims

Now to my understanding, whenever I go over bumps, it will change the tie rod angle and cause the wheel to turn slightly...

What could I do to minimize the amount of bump steer? I thought about setting the preload on my springs stiffer, so whenever I go over bumps the springs won't compress as much and my tie rod angles won't change much either. But then if I do stiffen the springs, theres more of a chance that I will lose traction.

[MechanicalChris]

Take a photo of your current suspension arm angles with the car on the ground and post them up.

[l__i__l]

i think u mean tramlining....part of the fun of owning a dc5

tyres are the main thing get something with soft sidewalls

[ChargeR]

The best way to solve bump steer is to get the car on an alignment rack, remove the springs from the coilover, re-fit the top mount and the strut then raise and lower the car through the range of the suspension, all while measuring the toe. Then using a spherical tie rod end, not inverted like the 0857 ones, and space the tie rod end up and down from the steering arm on the coilover until the bump steer is what you want it to be. No-one does this though, however if you take your car to a real race suspension workshop they will do it for you, probably at significant cost, since the tie rod ends will have to be made from scratch.

This is the only way to firstly be sure you are actually treating a real problem, what you are feeling is probably more correctly called steering kickback or tramlining, which is a problem even on a stock DC5 chassis, and is exacerbated by stiffer springs, shitty coilover designs, stiffer dampers, lowering and predominantly lower wheel offsets and tyre sizing. Secondly getting the car on an alignment rack is the only way to be sure you are actually having a positive effect rather than just throwing parts at the car.

This point is important: The DC5 front suspension when unmodified has toe-in in bump as per THIS thread, and the only way to promote toe-out in bump, which is what we want to get back to something approximating zero toe change in bump, is to raise the outer end of the tie rod, or lower the inner end. The smart kids at Realtime Racing did this, and they are not dummies:

[stevan]

So basically Tom Inverted Tie End rods and the steering arm relocation bracket do the OPPOSITE with regards to bump steer tuning then desired?

OP your car has very low offset and wide wheels with a ton of camber, your car would be acting like its on a knife edge due to tramlining which will force the wheels in the path of least resistance along the road undulations as Tom said. I have this "problem" as well but its something we have to live with. lower profile tyres with stiff sidewalls don't help the situation.

[Lemmiwinks]

Thanks for the replies. After reading the definition of tramlining, it's pretty much what I'm experiencing.

Here are the pictures of my tie rods:




Couldn't get a photo of both left and right tie rods as my airbox is in the way. But the tie rods are fairly straight, estimating a 10mm drop in the middle where the steering bracket is. This is with the car on the ground.

Took my car down to Techsport last Thursday to get my wheel alignment done, and we had to run 3.6 degrees of camber to fit them in the guards. So I'm guessing, with the amount of camber I'm running it would cause the tyres to grip the dips in the roads etc.

Tyres are brand new 235 40 18 Dunlop Z1 All star's. If I lower the air pressure of the tyres, would this minimize the amount of tramlining?

I would obviously try and lower the tyre pressures and take it for a drive, but I live in metro melb where the roads are fairly consistent and wouldn't be able to test it out unless I drive out to the rural. The tramlining problem only occurs on poor road surfaces.

[ChargeR]

So basically Tom Inverted Tie End rods and the steering arm relocation bracket do the OPPOSITE with regards to bump steer tuning then desired?

If believe so, if the measurements taken by the guy in the thread I linked are correct, and I think they are. It makes me wonder why Mugen chose to invert the tie rods on my N1 coilovers, I have a few ideas but I'd love to know what was going through their heads.

[stevan]

The only thing i can confirm regarding this is that at stock Tie Rod angles the steering feels much lighter, maybe the inverted ends had nothing to do with bump steer tuning?

[plAythiNG]

I have quite a bit of tramlining on my car. 17x9.5 +25 235/45 tire. Just concentrate hehe.

[Lemmiwinks]

The only thing i can confirm regarding this is that at stock Tie Rod angles the steering feels much lighter, maybe the inverted ends had nothing to do with bump steer tuning?

I didn't end up installing my inverted tie rod ends as the raised steering bracket was enough to make my tie rods fairly straight. But with the raised bracket, steering response has improved.

[cordz]

Okay time to bump an old thread.

Guys, i installed HSD HR coil-overs about a month ago on my DC2R. The install was done by my friends and i and if you caught a glimpse of my car at the BBQ it is actually quite low.



In fact, the car is low enough to have the exhaust scraping on certain speed bumps along with the lip. Guards cover tire by probably 0.5 cm (front). Rear height is perfect.

The car has not been wheel aligned, or had any supporting modifications.

I feel that the steering has actually deadened a little after the installation and the input used to change direction has increased slightly.

I believe bump steer is now significant but it may also be a bit of tram-lining.

I want to rectify this problems by raising the car an inch at the front, installing extended ball joints, and Hardrace spherical tie rod ends, (http://www.jhpusa.com/store/pc/viewP...idproduct=8571), getting this all done with a wheel alignment at a shop.

Will these products actually help?

Or is it a issue of just "raise the damn thing"?

[ChargeR]

Okay time to bump an old thread.

Guys, i installed HSD HR coil-overs about a month ago on my DC2R. The install was done by my friends and i and if you caught a glimpse of my car at the BBQ it is actually quite low.

http://farm7.staticflickr.com/6044/6...3e5484c1_b.jpg

In fact, the car is low enough to have the exhaust scraping on certain speed bumps along with the lip. Guards cover tire by probably 0.5 cm (front). Rear height is perfect.

The car has not been wheel aligned, or had any supporting modifications.

I feel that the steering has actually deadened a little after the installation and the input used to change direction has increased slightly.

I believe bump steer is now significant but it may also be a bit of tram-lining.

I want to rectify this problems by raising the car an inch at the front, installing extended ball joints, and Hardrace spherical tie rod ends, (http://www.jhpusa.com/store/pc/viewP...idproduct=8571), getting this all done with a wheel alignment at a shop.

Will these products actually help?

Or is it a issue of just "raise the damn thing"?

I have bolded what may be your problem. You really haven't got a wheel alignment? Get a wheel alignment with zero toe at the front and a few mm of toe in at the rear and then report back.

[cordz]

haha It's definitely something i have been putting off!

Any recommended shops in sydney?

Especially any that can rig a extremely low car?

[plAythiNG]

As what Tom edited in Bold. Very surprised you havnt got that done initially, as its the cheapest option and almost everyone does one after tinkering with the suspension.

I highly reccomend Jax Tyres in Liverpool. Could be a bit far for you up in Sydney's North. Heasmans is another reputable place (however their only open mon-fri (speak to Chris - him and his father love their Hondas and he'll know whatsup))

I do know that a few guys have also said Spinning Wheels in Alexandria also.

Touge Tune/Ben reccomends Jax Tyres (forgot the suburb - but its the one off Parramatta road, en route to the City/Boradway)

[Lemmiwinks]

Definitely get a wheel alignment! It's a must whenever you touch the suspension system.

It would probably be a good idea to ask the workshop if they can get low cars onto their alignment hoists when you ask for a price. As 3/4 of the hoists I've been up have had about 10mm clearance between my sideskirts and the ramp, and that's with my car being 150mm off the ground!

Also want to add to this thread that I minimized a lot of my bump steer by aligning my car to 3mm toe-in, instead of 1mm toe-in. Car drives 10 times better!