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Steering angle changes when weighting/un-weighting front end
I've only owned my FD for about three years, but one thing I noticed literally the first drive was that the steering angle seems to want to change depending on if the front is weighted or not. At first I chalked this up to 30 year old bushings, but after recently replacing all the suspension & steering rack bushings, the problem almost seems worse!
While driving straight down a road and hitting small bumps, the steering will pull slightly left or right making the front end sort of squirm around.
On a wide, constant turn, applying some throttle/letting up will actually cause the turn radius to change! Weighting the front of the car will cause it to steer in more sharply, un-weighting the front will cause it to steer out more.
Assuming you are close to factory ride height, there will be some toe change in roll, but what you are noticing is probably a combination of scrub radius and castor angle. They have aggressive geometry to present the treat the the road in turning/roll, the consequences is steering weight/feedback.
...On a wide, constant turn, applying some throttle/letting up will actually cause the turn radius to change! Weighting the front of the car will cause it to steer in more sharply, un-weighting the front will cause it to steer out more.
What the heck is going on?
At least part of that is the Torsen limited slip. When you accelerate, torque and weight transfer make the car want to go straight because the differential is no longer "free." It's a mild form of what happens when you try to turn any vehicle with a solid rear axle.
I've only owned my FD for about three years, but one thing I noticed literally the first drive was that the steering angle seems to want to change depending on if the front is weighted or not. At first I chalked this up to 30 year old bushings, but after recently replacing all the suspension & steering rack bushings, the problem almost seems worse!
While driving straight down a road and hitting small bumps, the steering will pull slightly left or right making the front end sort of squirm around.
On a wide, constant turn, applying some throttle/letting up will actually cause the turn radius to change! Weighting the front of the car will cause it to steer in more sharply, un-weighting the front will cause it to steer out more.
What the heck is going on?
all that sounds normal... have you driven a car that does not behave this way?
So you're driving it again? Congrats on getting it back on the road!
That 2nd line sounds like an alignment issue. In fact, it kinda all sounds like a toe deal to me. Too much toe-out in the front will definitely make the car wander. Maybe check the tires for weird wear?
Assuming you are close to factory ride height, there will be some toe change in roll, but what you are noticing is probably a combination of scrub radius and castor angle. They have aggressive geometry to present the treat the the road in turning/roll, the consequences is steering weight/feedback.
The car is fairly well lowered on stock wheels.
Originally Posted by Sgtblue
Not exactly the same symptoms but FWIW worn tie rods, and apparently loose steering rack bolts, can cause some odd alignment issues…
Unfortunately I think I can rule out tie rod ends and control arm balljoints as the tie rod ends are brand new and the control arm ball joints were also tight 800 miles ago. Perhaps it is the rack, I will give that a look.
Originally Posted by DaveW
At least part of that is the Torsen limited slip. When you accelerate, torque and weight transfer make the car want to go straight because the differential is no longer "free." It's a mild form of what happens when you try to turn any vehicle with a solid rear axle.
One thing that did chance at the same time the new bushings went in is that I had a shop show an RX-8 4.44 ring & pinion in the diff. Perhaps that is exaggerating what I am feeling.
Originally Posted by DaleClark
Really dumb but make sure your tires are all aired up. Low tire pressure will make the car super squirrelly.
Dale
I'll check the pressure and see if a little more changes it, thanks.
Originally Posted by gracer7-rx7
all that sounds normal... have you driven a car that does not behave this way?
Basically every car I have ever driven does it less!
Originally Posted by Natey
So you're driving it again? Congrats on getting it back on the road!
That 2nd line sounds like an alignment issue. In fact, it kinda all sounds like a toe deal to me. Too much toe-out in the front will definitely make the car wander. Maybe check the tires for weird wear?
Lets go for a spin, broham!
Forever not boosting right. Taking it back home this weekend to sort it all out once and for all (yeah, right...). It was running great, then out of nowhere don't boost past 0psi, pressure chamber isn't holding pressure, and the TCA sounds like it's half open all the time.
Agree it feels like a tow issue to me as well. For perhaps a bad wheel beaning. Had it aligned twice in the last six weeks including yesterday at Lloyds on River. They said it was all tight and in spec and didn't charge me.
Did you get your ride back? Definitely down to roll when I'm back in town.
I'm a **** hair away from getting the FD back. Paint and weather stripping is finished, just a few little button-ups and I'll be back trying to blow it up again! Definitely hit a brother up when you're back in SC.
Good deal on the alignment. Here's this anyway. It's from Pettit Racing. I use the "long track" set up.
The car is lowered, aggressively from what you've said. This may just be a symptom of that—the suspension arms are at greater angles, meaning more aggressive change when articulating, at at some point you do start to get some bump steer with a lowered car as well. HOW did you lower it (just springs, coilovers, is it cornerweighted, etc.)?
Stiffer springs, and stickier/wider tires increase the sharpness of reaction, and tramlining. A lot of camber can make it squirlier too.
Per GRacer, some of what you're describing is just the more pronounced reactions of weight transfer and dynamic suspension that are to some extent tuned out of regular cars, but are what you pay for with a sportscar. What is your previous experience driving?
Also another dumb question - have you had the car aligned? A bad alignment will have the car all over the damn place.
I really don't recommend any sort of track alignments for a street car. Get stock alignment for a car on the street. If you do some track time, stick with stock alignment. Track alignment is only for dedicated track cars and only if you are chasing that last little bit.
Tire pressure in the low-mid 20's is all it takes to have the car everywhere. It seems to really exhibit at on/off throttle.
And, as stated, super low ride height looks neat but is NOT functional. You just cause more problems with a super low ride height. Suspension needs room to work and if you slam it to the bottom of the travel you have no suspension any more, you have a Radio Flyer wagon.
Has the steering shaft been removed from the pinion at some stage? Does sound like a classic toe issue....and even if a supposed professional says it's good, a lot of alignment places aren't worth 2 bob!
The car is lowered, aggressively from what you've said. This may just be a symptom of that—the suspension arms are at greater angles, meaning more aggressive change when articulating, at at some point you do start to get some bump steer with a lowered car as well. HOW did you lower it (just springs, coilovers, is it cornerweighted, etc.)?
It's not slammed or anything, but perhaps on the low-er side. This photo makes it look maybe slightly higher than it actually as since it's a downhill slope on the far side of the vehicle.
Car sits on Ohlins with 11kg front, 9kg rear.
Originally Posted by ptrhahn
Stiffer springs, and stickier/wider tires increase the sharpness of reaction, and tramlining. A lot of camber can make it squirlier too.
Per GRacer, some of what you're describing is just the more pronounced reactions of weight transfer and dynamic suspension that are to some extent tuned out of regular cars, but are what you pay for with a sportscar. What is your previous experience driving?
I should have mentioned that I put new tires on at the same time as the bushings. Ride height stayed the same. The tires are Kumho V730 which are 200-treadwear with very little actual tread or water channeling.
Originally Posted by DaleClark
Also another dumb question - have you had the car aligned? A bad alignment will have the car all over the damn place.
Had alignment checked yesterday and it's in (stock) spec.
Originally Posted by DaleClark
Tire pressure in the low-mid 20's is all it takes to have the car everywhere. It seems to really exhibit at on/off throttle.
Just checked and all four corners are 29psi. Max for this tire is 51.
Upped it to 34 and see if that helps tomorrow.
Originally Posted by billyboy
Has the steering shaft been removed from the pinion at some stage? Does sound like a classic toe issue....and even if a supposed professional says it's good, a lot of alignment places aren't worth 2 bob!
No it hasn't been removed.
I hear you on the alignment places. I'll get it off the ground this weekend and see if anything seems loose.
Also another dumb question - have you had the car aligned? A bad alignment will have the car all over the damn place.
I really don't recommend any sort of track alignments for a street car. Get stock alignment for a car on the street. If you do some track time, stick with stock alignment. Track alignment is only for dedicated track cars and only if you are chasing that last little bit.
I do recommend Pettit's long track specs. .
What if you live 30min from the best road course in America and go there regularly, like we both do? Do you think he's daily driving the thing or using it for fun? Did you notice he mentioned that he's been to the alignment shop more than once in the last month and a half, and everything is stock, normal and tight? How many miles do you think are on his car, how many does he put on it monthly, and where?
There could be some factors to consider before saying that all alignment specs but yours are bad.
I also think this issue has nothing to do with the car being lowered. It's a low-mile car sitting on Ohlins, and I can definitely fit a couple fingers between the fender and tire. He's not as low as most of the FDs in the SF Bay Area and his car doesn't clunk, rattle or knock over bumps, so I'm thinking the suspension bushings are all good as well.
All that said, I'd probably take it to a different shop and check the alignment. .
This is another old thread which is linked to from my earlier “linked” thread posted above. Figured I’d put it up in case the OP missed it.
At any rate one bolt in-particular on the steering rack has a rare history of working loose and even falling out, allowing the rack to move and cause some weird stuff. If the OP’s symptoms came on suddenly it wouldn’t cost anything but time to put the car up, drop the undertray and check them. https://www.rx7club.com/3rd-generation-specific-1993-2002-16/check-your-steering-rack-mount-bolts-265138/
did it ever not drive like that?
wondering if there some mod you did that suddenly exagerated what you are feeling...
I've always noticed it, but it got worse when I, all at once:
1. Replaced all bushings
2. Switched from 11kg to 9kg rear springs
3. Put on new, gripper tires
To be honest, I didn't really notice it in the first few hundred miles after the above changes. I was a little distracted tuning a new rebuild. But that is what also makes me suspect wheel bearing because it seemed to suddenly feel worse.
Originally Posted by Natey
All that said, I'd probably take it to a different shop and check the alignment. .
I'm gonna check for movement/wheel bearings this weekend and probably give the long track alignment a try next time I'm doing one.
Originally Posted by Sgtblue
This is another old thread which is linked to from my earlier “linked” thread posted above. Figured I’d put it up in case the OP missed it.
At any rate one bolt in-particular on the steering rack has a rare history of working loose and even falling out, allowing the rack to move and cause some weird stuff. If the OP’s symptoms came on suddenly it wouldn’t cost anything but time to put the car up, drop the undertray and check them. https://www.rx7club.com/3rd-generation-specific-1993-2002-16/check-your-steering-rack-mount-bolts-265138/
Default to purple powerflex for most. Black for the front of the rear trailing arm. Mazda comp for inner rear lower arm and the large pillowball on the toe link. OEM for the small toe link and the rest of the 6x Pillowballs. Black on the rear where the bottom
of the shock bolts in.
I do recommend Pettit's long track specs. .
What if you live 30min from the best road course in America and go there regularly, like we both do? Do you think he's daily driving the thing or using it for fun? Did you notice he mentioned that he's been to the alignment shop more than once in the last month and a half, and everything is stock, normal and tight? How many miles do you think are on his car, how many does he put on it monthly, and where?
There could be some factors to consider before saying that all alignment specs but yours are bad.
I also think this issue has nothing to do with the car being lowered. It's a low-mile car sitting on Ohlins, and I can definitely fit a couple fingers between the fender and tire. He's not as low as most of the FDs in the SF Bay Area and his car doesn't clunk, rattle or knock over bumps, so I'm thinking the suspension bushings are all good as well.
All that said, I'd probably take it to a different shop and check the alignment. .
Wow, little harsh there!
A lot of those points I didn't know. I'm just trying to help out here. You'd be surprised how many times the basics are forgotten in the fog of modifying a car and it's important to make sure ALL the basics are covered.
Those alignment comments are pretty funny. Unless your car is strickly a dyno queen/drving miss daisy coffee shop car, factory wheel alignments are rubbish to drive on the road on even half decent fully groved street rubber, let alone even cheap semis. My rx7 was swapped week for week with my ute as daily driver before I did the water seal, my alignment would probably be between the long and short track settings.
Those are super duper conservative alignment settings imo. If you're interested in getting in touch with my suspension tech (Stanford educated, WTAC, etc), I'd be happy to recommend you. LMK
A lot of those points I didn't know. I'm just trying to help out here. You'd be surprised how many times the basics are forgotten in the fog of modifying a car and it's important to make sure ALL the basics are covered.
Dale
Didn't mean to be harsh on ya. Sorry about that, Dale. Like you, I'm only trying to help MKD get his car back on the track. Apologies for my little outburst.
MKD, hit me up before you take that thing back to Lloyd's. We may have a different, better option.
06-28-22, 08:50 PM
