Alignment help: caster adjustment

[HiToKiRi]

So yesterday I had 4 new tyres fitted to my vehicle after which I also had the wheel alignment done because I noticed some uneven wear on the outside edge of the left front (old) tyre.

So during the alignment process the technician calls me over to show me something on the monitor and he shows me that my "caster" is in the negative when it should actually be in the positive. He claims it's not a major issue but said it could explain the slight uneven wear I had on the old tyre because I'm most likely having to counter with the steering more than I normally would have to.

He says I either purchased the car like this (since I bought her second hand) or I could have hit a nasty pothole at some point (which I don't ever recall doing). He said he can't adjust the caster as there is nowhere to adjust it on a BMW but said if it becomes an issue I should maybe take it up with BMW.

I'm a bit unsure of what to do from here so I'm in need of some expertise. Can the caster be adjusted somehow (and if so by whom?) or will I have to consult with BMW directly and find out what they can do for me here?

I've attached the print out for reference.

Thanks.

 

[tivoli786]

could he not adjust the caster for you I know Tiger wheel can pull all sort of tricks out of a hat?

 

[HiToKiRi]

could he not adjust the caster for you I know Tiger wheel can pull all sort of tricks out of a hat?

Wasn't Tiger Wheel that fitted the new tyres...

Should I perhaps phone the closest branch to me and ask them if they assist?

 

[tivoli786]

That might be a plan as they have some unusual tools I remember the last time my RXi had some issues guy pulled aout a drill like tool made some new holes and Bob was my auncle.

 

[HiToKiRi]

Let me try that route and see what happens.

Thanks for the advice tivoli.

Much appreciated

 

[tivoli786]

no problem what is your mileage and has BMW ever done alignment for you as you get a free alignment every 30 000 kms dealer dependant. If you have never had alignment done call your nearest dealer and ask them if the cost is covered by motorplan and you sorted . Cost will be R1000 if you not covered otherwise take to Tiger wheel. From what I remeber they basically adjust using spanners

 

[moranor@axis]

caster is not adjustable stock... take this up with BMW because it indicates something is very wrong with the front end geometry on this car...

get them to do their own alignment readings and check the car

 

[Fordkoppie]

That might be a plan as they have some unusual tools I remember the last time my RXi had some issues guy pulled aout a drill like tool made some new holes and Bob was my auncle.

Drilling new holes in your suspension??:clapper:

 

[tivoli786]

That might be a plan as they have some unusual tools I remember the last time my RXi had some issues guy pulled aout a drill like tool made some new holes and Bob was my auncle.

Drilling new holes in your suspension??:clapper:

Lol no just saying they have skill I think it was the shocks been some time can't remember exactly where he used his tool a majig

 

[sash]

drilling should not be required.., if something is out of alignment it should be straightened(if possible) or replaced.

I was convinced of a similar tactic some years ago. The machine insisted the castor was off, even though after they set it up the wheel visually looked off. They refused to believe their eyes and just the machine. I damaged a perfectly good 17 inch in a single trip from durban to Pretoria...

When i replaced the tyres the TWT was dumbfounded at how off the alignment was and why they would consider drilling the holes on the shocks o allow adjustment..... school fees...

 

[HiToKiRi]

Just to update everyone, I actually took the car to my local TWT and had a chat to the wheel alignment guru of the branch (and also showed him the print out).

According to him and in his experience, the negative caster on the print out is within what BMW's would call "normal specs". He claims he's done alignment on several Beamers with similar readings and he's had some of these clients take it up with BMW as well only for BMW to come back and say that there is nothing to be concerned about. He actually went as far as to print me a report (for an E90 I think it was) which he did earlier today with a very similar reading.

He also said that caster has little to no effect on tire wear.

Here's an excerpt I took from anewtoronto.com:

Three to five degrees of positive caster is the typical range of settings, with lower angles are being used on heavier vehicles to reduce steering effort.

If the caster is out of adjustment, it can cause problems in straight-line tracking. If the caster is different from side to side, the vehicle will pull to the side with the less positive caster.

Even though it's very very slight, this is the effect I seem to be getting on my vehicle i.e. she does seem to tend to pull ever so slightly to the left. It's mostly noticeable on the highway when I let go of the steering. From my experience, most vehicles (who's alignment is correct) if one lets go of the steering would continue for a good few meters and then very gradually start veering to the left. With my bird, when I let go of the wheel it doesn't take her long at all before she wants to go left...perhaps I'm being OCD here?

caster is not adjustable stock... take this up with BMW because it indicates something is very wrong with the front end geometry on this car...

get them to do their own alignment readings and check the car

So in your opinion the negative caster is a definite issue?

I think I will take your advice and have BMW check it out. From what I read on several sites only two things generally cause caster issues:

1) The vehicle rolled off the factory floor that way
2) The vehicle was in a bad accident

---

Okay...did a bit more reading up on BMW's and caster settings/adjustments and multiple websites indicate that ALL BMW's have (or should have) positive caster:

All BMWs have slight positive caster, which creates an inherent stability when the car is moving in a straight line.

This piece of info particularly caught my attention (http://forum.e46fanatics.com/showthread.php?t=701092):

With Positive caster, road surface variations have a minimal effect on the tire, the tire will continue to go straight. When a tire has a Negative caster condition, where the projected steering axis point of load is behind the tire point of contact, a vehicle will have a tendency to be easier to steer but will lack directional stability. A vehicle with negative caster is affected by any road surface variation such as small road irregularities or bumps. With the point of load pushing the tire along (negative caster), any bumps or road irregularities which are encountered have a tendency to immediately affect directional stability and vehicle handling.

This is definitely something I experience. When I drive over speed bumps and as they put it, small road irregularities, my steering wheel does sometimes tend to jump around a bit (mostly to the left) and doesn't always stay centered. :thumbdo:
Is this normal?

So tomorrow I'll be arranging a very urgent visit to BMW. :lll._.:

 

[moranor@axis]

Take it to BMW just to be safe... I almost sure the alignment readout is wrong because the car should feel very unstable at speed with that caster

if the caster readout is not correct how good are the others? best to get the alignment done at BMW then if they pickup similar you also have it on record with them and can take it further

 

[HiToKiRi]

Take it to BMW just to be safe... I almost sure the alignment readout is wrong because the car should feel very unstable at speed with that caster

if the caster readout is not correct how good are the others? best to get the alignment done at BMW then if they pickup similar you also have it on record with them and can take it further

I really hope you're right man.
One thing I will say is she drives really nice at speed...I've encountered no stability or handling issues while stretching her legs.

I will take it in asap and get an official report from them.