Steering issue under braking !

[BRZZZZZZZZZZ]

Originally Posted by CSG Mike

This doesn't make sense to me; I've driven cars without power steering, and it doesn't have this type of effect.

I've noticed that front geometry has a large impact on how this phenomenon kicks in...

How were you able to determine that it's the electric power steering momentarily deactivating? It's not something we've ever logged or even put a sensor on, since we eliminated the issue on our cars.

I would of thought I would at least get a warning light or code thrown if that's what it was...

[glamcem]

Originally Posted by AJ PwR

Thanks everyone !

Couple years back, I had this issue already and I thought my car was too low. My car had about 1.5" drop and was running 235/40/18. It was hitting against the frame above the tire so I raised it about 0.5, lesser problems

This year I was running 265/35/18 problem still there and the recent track days I am running 245/35/18 (I have more wheel gap) , I have about 5 inches clearance between the tire and frame. I need to get on the accelerator sooner so when the weight transfers to the back, the problem goes away but this is not cool that I couldn't trail brake.

I did the pedal dancing so TRACTION is OFF at all times.

Here's what I am running at the front !
- RCA
- coil-overs with 8k springs
- front sway
- all bushings replaced
- roll center tie rods



I have not decide to come or not but if I do Rob will be driving !

Let me guess you experience that particularly when you get into the Turn 8a-8b and Turn 13 (corkscrew) at the RMP, correct?

Like I said I had the same issue with 235/40/17 NT01s and those are about .3" smaller then the OEM diameter but having 1.5" drop and softer damper settings were the reasons in my case

so, I would be surprised if you didn't rub with those sizes
for most tires 235/40/18 means about 25.4-25.5" overall diameter about .7-.8 " taller than the OEM diameter and 265/35/18 is still about .5-.6" taller

245/35/18 is ideal since it's the closest so the OEM size (just like the 245/40/17) so it probably happens because you either need:

• more negative camber
• and/or more poke (a bit more aggresive offset that takes it outward)
• and/or stiffer dampers/ adjustment (if adjustable)

at the last track day at RMP I was also trail braking and did the "pedal dance"
I wanted to try the softer settings (6-7 clicks from the stiffest) and it immediately started rubbing then using (1-2) clicks fixed that for me

FYI, I have 9k swift springs all around and don't use any roll center kit, sway bar or LCA.. I feel that I could've got 11-12k instead

Originally Posted by CSG Mike

This doesn't make sense to me; I've driven cars without power steering, and it doesn't have this type of effect.

I've noticed that front geometry has a large impact on how this phenomenon kicks in...

How were you able to determine that it's the electric power steering momentarily deactivating? It's not something we've ever logged or even put a sensor on, since we eliminated the issue on our cars.

yeah, I highly doubt that's the issue here and am not sure how/if it can be measured

[troek]

sub'd for a good mystery

[YodrOne]

Unfortunately I've experienced the same thing. For me it's most pronounced coming into turn 7 (the downhill before the straight) at Lime Rock. The suspension is compressed to the max at the same time that you're taking a fast right-hander.

I'm running RCE springs only, and use AD08R tires in 17/225. My guess is the tire is rubbing a bit against the spring, but I'm not seeing any significant evidence of this when removed. There's only about 5mm of clearance between the tire and the front spring so I've always assumed it could be taken care of with some 10mm hubcentric spacers (which I was about to get).

Would love to hear if it's more than that. Definitely a little disconcerting when you have to saw your steering inputs to get into a corner with that condition manifesting itself.

Here's what the corner looks like (towards the end, at the 55sec mark):
[ame="https://www.youtube.com/watch?v=cIwKCFiqfV0&list=UU5kiQpIyiYEL7ZdAZH7R2jw"]Scion FRS @ PCA NNJR Lime Rock 9-10 April 2014 - YouTube[/ame]

[dradernh]

Originally Posted by YodrOne

Unfortunately I've experienced the same thing. For me it's most pronounced coming into turn 7 (the downhill before the straight) at Lime Rock.

My guess is the tire is rubbing a bit against the spring, but I'm not seeing any significant evidence of this when removed. There's only about 5mm of clearance between the tire and the front spring so I've always assumed it could be taken care of with some 10mm hubcentric spacers (which I was about to get).

Are you seeing any evidence at all? A tire rubbing on a spring should leave plenty of evidence on the spring.

My experience has been that 5mm of tire to spring/coilover collar clearance is not an issue; however, that has been on other cars so YMMV.

[troek]

The tire shouldnt move any closer to the spring since the hub is fixed to the strut.(mcpherson)

[BRZZZZZZZZZZ]

Again I have had this issue a few times and my set up is not rubbing at all, so thats also out for me.

Its a mystery.

[tech86]

So it isn't just me! Have experienced a strange steering feel on the same corner a few times. Its a big right hander, front left gets loaded up well with the lowest speed through the corner being 90+ mph. (Turn 1 at Phillip Island GP circuit in AUS)

To describe it would be that the steering rack pauses or clicks and you're almost without power steering for a split second. Then its all fine. Doesn't do it every lap or every session but only ever on the same corner at the same track.

Only slightly lowered with about 2.5deg camber and decent rubber but there is no rubbing of any kind which would explain it.

Have had multiple people go over the entire front end looking for loose bolts or faults and couldn't find anything so it remains a mystery.

[Fender0122]

Back to the issue of overheating the rack, I remember reading something in the owners manual about the steering going stiff after extended "use" of the wheel. They equate it to a lot of quick side to side motion (I took that as fighting the wheel a whole lot) and it said to minimize quick motions and it will go back to normal. So maybe if you notice you're sawing at the wheel when it happens, try to be smoother and see if it goes away.

[BRZZZZZZZZZZ]

Originally Posted by Fender0122

Back to the issue of overheating the rack, I remember reading something in the owners manual about the steering going stiff after extended "use" of the wheel. They equate it to a lot of quick side to side motion (I took that as fighting the wheel a whole lot) and it said to minimize quick motions and it will go back to normal. So maybe if you notice you're sawing at the wheel when it happens, try to be smoother and see if it goes away.

I don't think that is what my problem is, I am a fairly smooth driver and mine usually happens under heavy braking as I let off to turn in.

[sw20kosh]

Tire rubbing

@CSG Mike @tech86 @BRZZZZZZZZZZ @AJ PwR @YodrOne @Element Tuning

[CSG Mike]

Originally Posted by sw20kosh

I had this exact issue!!! Fixed it via adjusting the sway bar end links to make them longer.

What was happening was the sway bar arms were hitting the frame of the car and thus getting stuck upon hard braking especially downhill when incurring a lot of drop in the front. The symptom was it was hard to turn steering wheel during braking and loss of front grip during this which caused front to "skip" and plow.

It will be obvious if your sway bar arms are binding on the frame. Check the frame for rubbing or damage.

It used to happen on the same corners and depended on how hard I was shifting the weight forward. Check your sway bars guys!

@CSG Mike @tech86 @BRZZZZZZZZZZ @AJ PwR @YodrOne @Element Tuning

There's a reason our car sits at the height it does...

[Element Tuning]

I had this problem with stock suspension and sway bars. It's the power steering motor overheat for me. It was brutal at Lime Rock and it's not that you can't muscle past it, it's just a problem with precisely calculating your steering input.

It's a knonw issue with this type of system but then again I was running 285 slicks and now 325s which I don't think many are. For sure check your end links but I had it stock also.

[dradernh]

Originally Posted by Element Tuning

It was brutal at Lime Rock...

In Big Bend? Anywhere else at LRP?