Front suspension and steering, how do you know you need to rebuild the steering? Options

[Superhawk996]

@DRPHIL914

Look at the picture of your tire positon vs. the intersection point where the McPherson strut would intersect the ground.

Unless what I'm seeing is an optial illusion of the photo, you have an outrageous King Pin Offset & large positive scrub radius. Typically, a McPerson strut likes some negative srub radius.

Ideally, you would like that intersection to occur at or near the center, slightly outboard of the contact patch. In your case the intersection appears to be near the inboard edge of the tire. (IMG:style_emoticons/default/yikes.gif)

Get the front wheel spacers out of there if you can without having the tire rub other things.

http://www.car-engineer.com/suspension-des...hicle-behavior/

[Garland]

Just snapped a couple shots for comparison.

73 white flared 9” rims, w/turbo tie rod ends



72 silver narrow body stock

[DRPHIL914]

@DRPHIL914

Rhodyguy is asking about the steering tie rods to the knuckle. You would like to see them close to parallel to the A-arm that you're showing. From what I can see of the tie rod in the background things look plausible.

I'll just tell you from experience that while a visual inspection isn't a bad thing . . . this will take some trial and error effort part changes. You're probably fighting a couple of differnt contributing factors here including those meaty, performance oriented tires. Wide tires with big solid block tread patterns without many sipes are only going to add to the tendency to "hunt" and/or follow road contours without steering input on your part.

Are you driving on a lot of rain grooved concrete highways by chance? Is that part of where your directional stability concerns are coming in at highway speeds?

thanks for explanations. the roads are not really grooved like you say but my main commute road was resurfaced a few years ago and is getting some shallow holes from that thin layer getting broken up so like here at there are a lot of those small holes or spots., speed limit is 60 but traveling with traffic tis more like 65-70.
I thought about the tires and treads and since I need to change had thought about a less pure performance tire and more of a compromise of performance/all season and even going to a 195/60 rather than a 205/55. more of a standard tread, slightly higher side wall, might feel better, I looked and my tires are almost 6 years old so I probably could change that very soon

[DRPHIL914]

@DRPHIL914

Look at the picture of your tire positon vs. the intersection point where the McPherson strut would intersect the ground.

Unless what I'm seeing is an optial illusion of the photo, you have an outrageous King Pin Offset & large positive scrub radius. Typically, a McPerson strut likes some negative srub radius.

Ideally, you would like that intersection to occur at or near the center, slightly outboard of the contact patch. In your case the intersection appears to be near the inboard edge of the tire. (IMG:style_emoticons/default/yikes.gif)

Get the front wheel spacers out of there if you can without having the tire rub other things.

http://www.car-engineer.com/suspension-des...hicle-behavior/

Just snapped a couple shots for comparison.

73 white flared 9” rims, w/turbo tie rod ends



72 silver narrow body stock

ok will pull the spacers too, really don't need them. i had then in there when i had 7" rims in rear but went back to the 6" all around.

- looking at those pictures Garland, your A-arms are parallel with the ground and mine are not, but could be a bit of an optical illusion. Scrub radius etc lol i am learning stuff today ive been ignoring and not taken the time to really dig into!. But all really interesting! need to get in there and look closer at the alignment and measure the camber, caster, toe in etc etc .

[Superhawk996]

@DRPHIL914

Look at the picture of your tire positon vs. the intersection point where the McPherson strut would intersect the ground.

Unless what I'm seeing is an optial illusion of the photo, you have an outrageous King Pin Offset & large positive scrub radius. Typically, a McPerson strut likes some negative srub radius.

Ideally, you would like that intersection to occur at or near the center, slightly outboard of the contact patch. In your case the intersection appears to be near the inboard edge of the tire. (IMG:style_emoticons/default/yikes.gif)

Get the front wheel spacers out of there if you can without having the tire rub other things.

http://www.car-engineer.com/suspension-des...hicle-behavior/

Just snapped a couple shots for comparison.

73 white flared 9” rims, w/turbo tie rod ends



72 silver narrow body stock

ok will pull the spacers too, really don't need them. i had then in there when i had 7" rims in rear but went back to the 6" all around.

- looking at those pictures Garland, your A-arms are parallel with the ground and mine are not, but could be a bit of an optical illusion. Scrub radius etc lol i am learning stuff today ive been ignoring and not taken the time to really dig into!. But all really interesting! need to get in there and look closer at the alignment and measure the camber, caster, toe in etc etc .

I'm hoping it's an optical illusion. Look at Garland's photos, note the bottoms of the ball joints are partially tucked within the wheel. Due to the ange of the strut (inboard at top) that intersection to the ground plane is going to occur closer to the center of the tire contact patch.

Garlands's 9" rim seems to be tucked in a bit further. This isn't rally about rim widths, but rather about wheel ofset and the length of the scrub radius.

The other thing to keep in mind is that one person perceives as stable, controlled, and responsive can be another person's darty and unstable. It all depends on what you're used to driving and how readily you adapt between vehicles.

[Garland]

Arms look to be just off parallel.
I was involved in the alignment on the flared car, with rack spacers, and a wheel spacer. We set the ride height first, lower then stock, but with still being able to correctly set toe, and camber/caster.

[Superhawk996]

@Garland

Who did your aligment? I no longer have a go to shop in the metro area. I have a long time unitl I need a shop but it would be great to have a shop that actually has worked on a 914 once before.

Last time I went to one with a 914 they insisted they needed a special tool to loosen the top mounts. When I provided them with the allen wrench. They refused to do the job stating they had to have the "special tool".

I used to use a little shop called Bruces Alignment on Woodward Ave, in Royal Oak back in the day to do my Miata alignment for Autocrossing but unfortunately the Yuppie / Trendy empire of Royal Oak & Birminham eventually made that retail space on Woodward to valuable and forced Bruces out of thier space.

[Jamie]

This could be as simple as adjusting toe angle, which has a significant effect on straight ahead feeling of steering stability. An off toe will cause the steering to wander a bit at speed, rather than steering steady straight ahead.

[mepstein]

@Garland

Who did your aligment? I no longer have a go to shop in the metro area. I have a long time unitl I need a shop but it would be great to have a shop that actually has worked on a 914 once before.

Last time I went to one with a 914 they insisted they needed a special tool to loosen the top mounts. When I provided them with the allen wrench. They refused to do the job stating they had to have the "special tool".

I used to use a little shop called Bruces Alignment on Woodward Ave, in Royal Oak back in the day to do my Miata alignment for Autocrossing but unfortunately the Yuppie / Trendy empire of Royal Oak & Birminham eventually made that retail space on Woodward to valuable and forced Bruces out of thier space.

Special tool is a joke. You can take apart an entire 914 with a shoebox of tools.

[rhodyguy]

When I bought mine it was the pucks, longer bolts and some washers. IIRC. I prob bought them at pelican.

[jmitro]

This could be as simple as adjusting toe angle, which has a significant effect on straight ahead feeling of steering stability. An off toe will cause the steering to wander a bit at speed, rather than steering steady straight ahead.

bingo.

Superhawk996 really knows his stuff but I think we've jumped to the conclusion you have bump steer problems without any real evidence to say why. Unless your car is lowered substantially from stock, bump steer is less likely to be the cause. it sounds to me like you have a lot of toe out. when was your alignment last checked?

as far as rebuilding the steering rack - that sounds like a last resort in my mind, given the complexity of the job; However, if you end up replacing the rack, you'll maintain your alignment settings or (preferentially) get a new alignment.

one other thing - the front US ride height was raised (as I understand it) compared to euro ride height, without any need for adjusting bump steer, which means to me that you can lower the car below euro ride height without major bump steer.

this is what I would do in order of complexity:
1. check and confirm that alignment is correct
2. check and confirm no significant bumpsteer (I forget the exact dimensions but I'm thinking less than 1 degree throughout the entire suspension travel)
3. if that doesn't help, look at the hockey puck. replace if bad (requires removing fuel tank)
4. rebuild steering rack

[Superhawk996]

I don't necessarily dis-agree with @Jmitro in that we may have gotten a bit ahead of ourselves w.r.t. to bump steer but based on the desription initially offered, it aligns very well to the symptoms of bump steer.

We do know the wheel/tires were changed and front wheel spacers were added which can make the 914's inherent bump steer characteristics worse.

I have assumed alignment is OK based on @DRPHIL914 description that all components were checked, replaced recently, are not loose, and I'd assume properly aligned at that time these components were swapped.

Let me modify the Jmitro sequence only to do what is free and easy:

1st step - Remove the 1/2" front wheel spacers and then report back.

Lacking any other changes in wheel offset that could have occurred going from 14" to 16" wheels, the front wheel spacer immediately adds scrub radius. Increased scrub radius increases steering & parking efforts, and decreases straight line stabiltity when there are road induces disturbances (bumps, lane ruts, or road camber).

Increased scrub radius only compounds any other problems that might be there.