RE-71RS rolling over. Soft suspension?

[foodtruck]

I had a bizarre experience at last weekend's autox where I was trying out new set of RE-71RS in 215/45r16. The front pair running at 43 PSI (which I gather is a fairly high pressure) was rolling over onto sidewall in hard turns. Few years ago I was running the original RE71R and did not have this problem. Front camber is at -2 degrees which is more than I had with RE71R.

The only other thing that stood out is folks at the event commented about the amount of nose dive on the outside front corner during the turn. So now the question is whether the stock suspension is too soft or has worn out, allowing for extra flex, and what can be done about it. Someone suggested to install a rear sway bar which would theoretically make the rear rotate earlier before the tire collapses, however wouldn't that make the car unstable in slaloms? Camber bolts will likely allow for another half of degree but this seems like a bigger problem than that half degree can solve.

Has anyone gone through the same with their Fiesta?

 

[Jabbit]

What other mods? How wide are your wheels? Those are fairly sticky tires for a stock suspension ST.

 

[Pablo Pistoffo]

That is pretty odd, I wouldn't expect much rollover at that kind of pressure (although i have no experience with the new Bridgestones. One thing you might want to check is if your tire gauge is still accurate, but that's about all I could think of.

 

[SteveS]

Your struts could be worn out, allowing more dive & squat.

But what wheel width are you using? It may be too narrow for the tire.

View: https://youtu.be/1MDq23scaWw

 

[tri-pedaler]

Your struts could be worn out, allowing more dive & squat.

But what wheel width are you using? It may be too narrow for the tire.

View: https://youtu.be/1MDq23scaWw

Was thinking of the same Tire Rack comparison - really helpful.

 

[foodtruck]

Rims are 7" wide Enkei j10. Tire walls look pretty vertical, i.e. not leaning in or anything.

 

[foodtruck]

What other mods? How wide are your wheels? Those are fairly sticky tires for a stock suspension ST.

Yes, I've been suggested that the tire might be overworking the suspension. The only confusing part is like I mentioned earlier I had similar tire on the car and it didnt have these issues. Also seeing how other Fiesta owners successfully compete on Potenzas in HS without major suspension mods makes me lean towards worn out strut theory, they would be turning 10 next year and the car has been autocrossed every single one of them.

But yes, seeing how Im in STH, I would also welcome mod solutions on how to make the front roll less without changing the car dynamics too much.

 

[foodtruck]

That is pretty odd, I wouldn't expect much rollover at that kind of pressure (although i have no experience with the new Bridgestones. One thing you might want to check is if your tire gauge is still accurate, but that's about all I could think of.

It was incredibly odd to me as well! And also very disappointing, I was really looking forward to having a competitive tire for this season. I booked an appointment with a local shop next week to look at the suspension; hopefully we'll see something obvious like visibly failing bushings.

 

[foodtruck]

Your struts could be worn out, allowing more dive & squat.

Is this something that can be conclusively determined in a shop or is it one of those things where I need to just take a leap of faith and replace it and see if it improves things? This year I noticed my rear shocks are weeping so given the age I guess its plausible that the fronts are not too healthy as well.

 

[tri-pedaler]

my rear shocks are weeping…

Sounds like you may have your answer.

Now what new shocks to get?

 

[SteveS]

10 years old and leaking hydraulic fluid. They are done. Even if the rears are the only ones that are bad, they can cause excessive dive and squat.

In STH you have free choice of the available replacements. If you want to retain a conventional strut setup you can go OEM, Bilstein in a couple of flavors, or Konis in a coupe of flavors. You can replace springs or not. Or you can go to coilovers.....

 

[faust]

FWIW, I drove a '17 with that exact tire this weekend, at slightly lower PSI (on the owner's gauge at least), and there was no rollover.

The front shocks on my '15 were weeping at 4 years / 40k. I'm in H Street so replaced them with B6s, which have been fine.

 

[WannabeST]

There's multiple points of concern here for me. While it sounds like you narrowed down your main issue to the shocks there's multiple things which could be improved on.
1 - Tire pressure was WAY too high, tire pressure should really be in the low to mid 30s, tire pressure gauge may be off calibration?
2- a 215 wide tire is way too big for a 7" wheel. for a 215 tire you should have MINIMUM an 8" wide wheel. Otherwise you could probably run a 195 and get the same if not better results. Your 215 on a 7" setup will cause the sidewall to flex and make the car over work the sidewalls.
3 - It sounds like you need more camber up front, Ideally around -3 camber to get good use of the tire then add if necessary from there
4- the new RE71RS is WAY faster than the RE71R. The tire is breaking multiple records here in socal. 200tw tires are only getting faster and faster and I think it's fair to say the RE71R is now an old generation tire left in the dust. Whole new driving experience now.
If I were you, I would keep the tires given they are fast and proven. Get new shocks since we've concluded they are on their way out already, lower tire pressures. and as soon as budget allow add camber and get wider wheels. You're not using the full benefit of a 215 wide tire with 7" wide, you ideally need a slight stretch. This helps the sidewalls be stiffer.

 

[foodtruck]

2- a 215 wide tire is way too big for a 7" wheel. for a 215 tire you should have MINIMUM an 8" wide wheel. Otherwise you could probably run a 195 and get the same if not better results. Your 215 on a 7" setup will cause the sidewall to flex and make the car over work the sidewalls.

Interesting, but wouldn't a stretched tire be more prone to rolling over onto sidewall since the sidewall is already leaning towards the ground due to the stretch? But I suppose if there's enough camber, that takes care of that...

Yes, the grip of these tires is absolutely phenomenal; even in the hamfisted turns that resulted in the rollover there was barely any understeer at all. Definitely keeping them for now, at least until I try to fix the suspension.

 

[foodtruck]

Now what new shocks to get?

Great question!

In STH you have free choice of the available replacements. If you want to retain a conventional strut setup you can go OEM, Bilstein in a couple of flavors, or Konis in a coupe of flavors. You can replace springs or not. Or you can go to coilovers.....

I know for sure that I

* Want to lower the car as little as possible
* Hopefully keep most of its dynamics (except the current diving!)

I think I narrowed it down to KW V3s and Konis...

* KWs are appealing because all of the adjustments are at the bottom and I know they can be rebuilt when they finally go
* Konis seem to be widely used in autox but some say fronts had some fitting issues and there's no mount for vibration dampener? Also the rear adjustment is awkward.

From others I've considered but don't know much about:
* ST XTAs seem to be KW-lites w/ cheaper components
* I've read some bad reviews about Bilsteins in more recent years, not sure if there's any truth to that or not

There's also stock setup of course, however yes, given that I'm in STH now, feels like it would be a shame if I didn't use the flexibility that the class allows. I kind of worry that I put the stock struts on and the tires will still overpower them.

I would lean towards KWs however I have difficulty finding any extensive reviews for them for our vehicle (especially how they are comparing to stock at autox). I'm pretty sure that I'll be able to tune them to have the car drive like I want it to but I worry that they will be too jarring for daily commute.

I'm also thinking the next step is to replace the front bar with the one from 2016+ model which is supposedly 30% stiffer. Not a huge difference, but perhaps will help keeping the front flat.

Would greatly appreciate any feedback on any of the above!

EDIT: Leaning towards KWs, not Konis

 

[WannabeST]

Interesting, but wouldn't a stretched tire be more prone to rolling over onto sidewall since the sidewall is already leaning towards the ground due to the stretch? But I suppose if there's enough camber, that takes care of that.

A good example is drag racers. They will put oversized tires on to smaller wheels. If you see the really fast guys launch, their sidewalls will flex. For them, this gives them grip to launch. But imagine your sidewalls doing that while you're mid corner.
your sidewalls flexing like a drag racer is going to give multiple poor effects. For one, finding the limit of grip is going to be hard because instead of the tires losing grip smoothly the sidewalls will start flexing which can make the "break away" feeling of grip way more sudden and way less forgiving. Also because your sidewalls flexing also lowers your "useful" contact patch because of how much the shoulder flex. Sidewalls flexing most of the time will lead to understeer because the tire doesn't want to turn. A slight stretch is ideal, it'll help to strengthen the sidewall a little and the proper size prevents sidewall flex. Obviously we don't want stance nation stretch because then on track you would be risking a tire debead. But a perfect example of what you should run for stretch is 205 wide tire on an 8" wheel. Keep in mind different tire companies have different "205" size tires but 205 on an 8" is a really good handling size and can be seen a lot on 90s hondas

 

[WannabeST]

Interesting, but wouldn't a stretched tire be more prone to rolling over onto sidewall since the sidewall is already leaning towards the ground due to the stretch? But I suppose if there's enough camber, that takes care of that...

.

This is my daily on track with 185 wide all seasons on the stock 6" wide wheels. Your tires are 30mm wider and your wheels are only 1" wider. 30mm = roughly 1.2 inches. So your tire is 1.2" wider than mine but your wheel is only 1" wider. So even tho your tire has a sidewall 10x stiffer than any all season. Your tire to wheel ratio is technically worse than my daily driver, and this is the oem setup. Your tire most likely looks like this while cornering. Not as severely since you have a 10x better tire. But it will be doing this effect.

 

[SteveS]

The other thing to consider is that 8" is NOT stretch for a 215/45 tire. the recommended rim width is 7-8" for that size. The car came with 205s on a 7" wheel. That's a perfect fitment. The 215 is oversize for the 7" wheel. The 8" is the right size.

 

[jeffreylyon]

EDIT: Leaning towards KWs, not Konis

I had the ST XTAs - garbage springs, plastic hardware, crummy coatings. I dunno how much better the KWs are but, for the price, it better had been a lot. There are some really good options for $100's less.

 

[foodtruck]

The other thing to consider is that 8" is NOT stretch for a 215/45 tire. the recommended rim width is 7-8" for that size. The car came with 205s on a 7" wheel. That's a perfect fitment. The 215 is oversize for the 7" wheel. The 8" is the right size.

FWIW this is how the fitment looks like right now... Did not look distinctly different from how old RE71r looked like in 205/50 so I didn't think twice. Going to see if I can find any rims in 7.5-8" width.