I am not very clued up on car things or terms when you say bumps steer do you mean the car wanting to go one way or the other going over uneven road ? if yes then you are correct…
When the front of my car goes over a bump it wants to go one direction and when the back end goes over the same bump the car wants to go the other direction… so it takes a tight grip of the steering wheel and quick steering wheel manouvering.
It is nowhere near as bad as it was before this recent alignment however it is still a nuisance…as you have already guessed i’m all about the feel of the car be it throught the seat ( tyre pressure) or how the tyres contact with the road and if one or the other is off it limits my driving skills… it’s the difference between me driving like im in fast and the furious and taking or driving miss daisy…
I mean a big example was the front camber was a tiny bit positive but still within spec and since they adjusted it i can feel the difference when cornering… something they told me i wouldn’t even be able to tell… maybe this car just over exaggerates the tiniest differences…
Yup, that’s bump steer. Technically, it’s when the tire changes steering angle as it travels through its range of motion. This can happen to both the fronts and rears.
and the way to fix it is to design it properly in the first place. After that, it involves relocating the suspension attachment points or changing the steering rack idler arm length (with appropriate changes to the overall length of the rack.)
So is the problem one of when you hit a bump? Is it a nervous feeling? Or is it the constant off angle?
yeah it’s not quite as bad after this most recent alignment which makes me think we are almost there… however prior to it, i would grab my steering wheel very tightly when approaching rough or bumpy road as the car would want to go left/right and i would just need to hold on tight to get through it.
the worst would be when turning into a street that had a ramp at the beginning of the road… the mixture of the angle of turning and the ramp/speed bump would send the car all over the place.my passengers thought they were on a rollercoaster… even when i was sitting at 5mph.
yeah i guess it’s a nervous feeling… due to having people in my car sometimes young kids etc… if it was just me alone i would be flooring it and dealing with it without any major issues… i guess just knowing something is slightly off with people in my car adds another level of nervousness.
Based on that last post, I do not think we are going to fix this problem - unless the caster is the source of the problem. Next alignment, make sure you get that value.
@Just_Made@VOLVO_V70 just a note in this thread, because the other one is gone now, I believe. Autobee is gone, and is definitely not @Just_Made. They were in different countries, and this happened to a couple of users.
the different countries thing could still have made it me… use of a vpn would chose a fake i.p and such however that is not the case and whoever it was just took my post for whatever reason thanks for the update man.
yeah i will get the caster printout also when i take it in on friday…
just curious if the rear right toe is an issue… having both front wheels at zero toe and a perfectly straight steering wheel, when driving would the car not continure to drive straight if held tightly dead centre despite the back end wanting to push to one side ?
Jus twondered as this a fwd, i thought the back end would just drag along, yes the back right might have uneven wear .
yeah i’m nervous due to the car having an issue… i also had another car last month that i used for work and had zero issues driving with people in it… and never had any issues with previous cars while working… i’ve been a taxi driver for 9 years…
If i’m feeling nervous while driving it is down to the car making me feel this way, not my skills as a driver… as i’ve got on with it and haven’t crashed or put anyone in danger… i just choose to drive a lot more cautiously now.due to the issue… but it’s limiting my daily intake.
For example when setting off at lights i need to hold the biting point longer than i usually would to make sure the car is going in the right direction…
ill have a look at previous alingments to see if i can see one with a caster printout.
Well, there is one thing we haven’t discussed and that is tire conicity (Root word: Cone). Conicity is the sideways force a tire generates just by rolling and it varies from tire to tire.
Ideally you want tires paired on an axle to have the same value (or within the sensitivity range of the vehicle). Having mismatched tire conicity causes a steady pull. That’s why I suggested swapping tires around - to see if there is any large swings in the pull that would indicate large changes in tire conicity.
But based on the above, I think we are talking about a vehicle design issue - specifically, bump steer.
here is a previous alignment done maybe a month ago… it has caster readings which are in spec… however i have had alignment printouts with both out of spec… infact every alignment prinout i’ve got shows one part or another being out of spec at some point some only taken a week apart
Question for Capriracer:
Isn’t it a bit unusual for a Fwd car to have a positive toe in?
The generation of fwd cars I’ve worked with always had negative toe “in” - something like -0,06 to compensate for the pull from the front wheels. Even my -95 Opel Astra F specifies -0,05 to -0,20 toe in (out).
I’m a tire guy, not a vehicle guy, so I am not the person to ask.
BUT -
I think the suspension determines whether or not the toe changes while under power and I can imagine both additive and subtractive toe depending on what the suspension is doing.
would this be the slight bulging at the bottom of the tire ?
I only ask as this seems to be a consistent problem at the front end of my car… it’s happened with each set of tyres and seems to worsen the longer the tires are on the car.
It can’t be anything to do with being underinflated as i’ve inflated them all somewhere between the minimum and maximum recommendation on the door sticker… as a happy medium for changes in load through my shift.
but both front tyres always develop a bulge at the bottom regardless as if they look underinflated.
Obv jokes… but yeah the front bulge i’m wondering if it might have something to do with the car wandering a bit also… since you’re the tyre guy thought i’d get your input
Toe cannot be measured on Independent rear suspension by measuring the gap between the front and rear of the tires. The dynamic center of travel must be determined and from that point left and right toe can be measured. On the other hand FWD independent suspension toe must be measured by first setting the steering gear at dead center (wheel pointing straight ahead) and then adjusting the left and right wheel toe to the center.
And I welcome an alignment pros correction of my terminology and/or accuracy in my explanation. While I have aligned quite a few RWDs over the years I know enough about FWD alignment to understand when it’s time to send a car to a real alignment pro. And the old mechanical caster-camber angle gauges gave mechanics an insight into the situation while modern equipment can be operated on a “monkey see- monkey do” basis with no understanding of what’s being done.
A 6 minute toe-in angle on both front wheels (or .1 degree) from my paper napkin calculations says the distance between the front and rear of 20 inch diameter tires would differ by about 0.07 inches.
