Drilling out strut mount holes to adjust Caster?

[GranPrix]

Hi, my 95 grand prix sedan has had a moderate pull to the right for 5 months now, I haven't noticed any tire wear, and I have checked every suspension/steering component and it all seems good. I have tried swapping the tires around to no avail. At this point I have determined it is more of an annoyance than a tire wear issue. I got an alignment and they adjusted camber and toe, but said that on these cars caster is non adjustable. I took off the plate on top of my strut to reveal the bolt holes, and discovered that they looked very ovaled out, like someone drilled them out to adjust caster? This would explain my pull, because Caster doesnt affect tire wear. Could I move the strut inside the ovaled out holes to change my caster angle and fix my alignment?

[55trucker]

When the alignment shop did the work did they provide you with *before/after* printout?

 

Off the assembly line there is no adjust at the front for camber as well as caster.

Oem front camber is approx .7 degrees POSITIVE

OEM front caster is approx 2.5 degrees

Front toe OEM is 0 degrees overall

 

If someone has ovaled the shock tower openings (there's nothing wrong in doing so) more than likely the holes have been opened towards the centre of the chassis to allow a negative direction for camber (not caster) adjustment.

Mild negative camber (by that I mean on the negative side of 0) will make the steering more responsive, a less *dead* feel to the steering, reduce understeer into aggressive corners.

Assuming (& I emphasize assuming) that the front is in spec then I would take the position that the pull to one side could be the rear track being out of adjustment.

If the shop did not have the special little tool (turnbuckle) to adjust the rear lateral bars then they would have an awkward time getting the toe set properly.

[GranPrix]

no they did not show me a before/after. they said the printer wasnt working at the time.

They told me they adjusted toe and a little bit of camber, maybe they loosened the control arm bolts and shifted the control arm over a little bit? The pull is sometimes very strong, and other times it will go away completely.

Could strut mounts or a strut bearing cause a pull?

I thought the cause for the pull was my outer tie rod end, which was worn and loose, after replacing and getting said alignment it has not changed the pull at all. while changing the outer, I checked the inner and it was tight.

Steering also feels Loose at 70+ MPH. I wonder if the rack is worn out.

something else to consider, I recall some Grand Prix's in the mid-late 90s to 2000s coming with an "intelligent" power steering system where it would reduce the power steering effect at higher speeds, and make the power steering more aggressive at lower speeds. Maybe if my car is equipped could this system malfunction and cause the power steering system to "favor" one side, causing a pull? Did some 95s come with the "intelligent" power steering system? if so what RPO code should I look for.

[rich_e777]

IIRC its NV7 for variable Power Steering assist, my `95 Vert has it. You won't find a replacement rack out there unless at the JY or luck up on ebay but good chance its from the yard too. You`ll have to have yours rebuilt if you suspect its going out. There is a bushing on one of the mounting bolts that could go bad as well as the subframe mounts could both affect the steering.

 

[55trucker]

8 hours ago, GranPrix said:

no they did not show me a before/after. they said the printer wasn't working at the time.

They told me they adjusted toe and a little bit of camber, maybe they loosened the control arm bolts and shifted the control arm over a little bit? The pull is sometimes very strong, and other times it will go away completely.

Could strut mounts or a strut bearing cause a pull?

I thought the cause for the pull was my outer tie rod end, which was worn and loose, after replacing and getting said alignment it has not changed the pull at all. while changing the outer, I checked the inner and it was tight.

Steering also feels Loose at 70+ MPH. I wonder if the rack is worn out.

something else to consider, I recall some Grand Prix's in the mid-late 90s to 2000s coming with an "intelligent" power steering system where it would reduce the power steering effect at higher speeds, and make the power steering more aggressive at lower speeds. Maybe if my car is equipped could this system malfunction and cause the power steering system to "favor" one side, causing a pull? Did some 95s come with the "intelligent" power steering system? if so what RPO code should I look for.

*printer not working* = idiots

at the front end there is no camber adjustment, (unless they themselves knew that the shock tower openings were ovaled & moved the strut at the upper end), there's no adjustment for the lower control arms either (the through bolts are a precise fit).

The strut bearings do seize up (depending on your geographical environment i.e snow/salt), when they go they will groan as the wheels are turned & the steering becomes stiff, (the techie doing the alignment would see
& hear this & should stop the service).

Loose rack?..alignment would fail, techie would/should not pass the steering inspection

As for variable assist........if your car has it there is an additional valve (electric over hydraulic) mounted to the pressure side port of the power steering pump, easily recognizable, there will be an electrical harness going to it.

I take it that all 4 tires are the same size?

Last but not least.....do you have a seized brake caliper at 1 corner?

 

 

 

[GranPrix]

I think the alignment has been off for a while and the shop was just stupid and did a “toe and go”. They Overcharged me too. I have some distant relatives that own a GM dealer I might be able to ask them if I can squeeze in and use their alignment rack myself. Thanks for the info about the strut mounts and magnasteer system though.