Is there away to measure castor on a car at home?

[rcx132]

Kwikfit told me that my castor and camber is out but they won't adjust it as it means loosening the upper wishbone and fitting shims. I thought I'd have a go at it at home.

I've levelled the car supported on axle stands at the hubs and measured the inclination of the wheel mating surface. It measures almost exactly what Kwik fit said it was (slightly negative due to suspension lift).

But I can't find a way to measure the castor. I have a self levelling laser level but I cant find an easy way to ensure it's at 90 deg to the hub to get the castor.

Wondering if anyone has found a way to measure this at home?

Edit: and any idea how Kwik fit were able to measure the castor as it's not something I can see could be measured without removing the wheel?

 

[voipio]

Caster angle can be measured by putting the front wheels on turntables, rotating them through a fixed angle, typically 20 degrees in either direction i.e. 40 degrees total, and measuring the change in the tilt of the wheel's axis of rotation. There are spirit bubble gauges available to facilitate the measurement, or a camber gauge could be used.

 

[rcx132]

Caster angle can be measured by putting the front wheels on turntables, rotating them through a fixed angle, typically 20 degrees in either direction i.e. 40 degrees total, and measuring the change in the tilt of the wheel axis of rotation. There are spirit bubble gauges available to facilitate the measurement, or a camber gauge could be used.

That has put me onto this formula found on another forum which calculates castor:

Caster (deg) = (180 / 3.1415) * [(camber1 - camber2) / (turnangle1 - turnangle2)]
turn angle 20 degrees each way = 1.43 x camber diff (commonly rounded up to 1.5)
turn angle 15 degrees each way = 1.91 x camber diff (commonly rounded up to 2.0)

Seems simple.

 

[AVI_8]

What make and model is your car?
Most cars have fixed castor and camber, adjustable camber with an eccentric nut is not unusual though on some cars.
Is the castor out due to worn components or a damaged/bent component
Shimming to get castor is not usual in my experience.
I would go to somewhere who specialises in alignment, Kwik fit would not be my personal choice.

 

[Trevorleach]

Kwikfit told me that my castor and camber is out but they won't adjust it as it means loosening the upper wishbone and fitting shims. I thought I'd have a go at it at home.

I've levelled the car supported on axle stands at the hubs and measured the inclination of the wheel mating surface. It measures almost exactly what Kwik fit said it was (slightly negative due to suspension lift).

But I can't find a way to measure the castor. I have a self levelling laser level but I cant find an easy way to ensure it's at 90 deg to the hub to get the castor.

Wondering if anyone has found a way to measure this at home?

Edit: and any idea how Kwik fit were able to measure the castor as it's not something I can see could be measured without removing the wheel?

Maybe they did not measure it at all, but could see from the tyre wear that the castor was out?

 

[AVI_8]

Maybe they did not measure it at all, but could see from the tyre wear that the castor was out?

Tyre wear is usually down to toe angle or sometimes camber if the camber angle has been modified or the suspension considerably lowered.

 

[optima21]

I once went to kwik fit for my exhaust to be replaced and they advised that I need the tracking adjusting on my cars rear suspension....... its a beam axle, there is no adjustment on it, its a solid piece of metal.... I had recently rotated my tyres so the tyre wear may have looked a bit odd, but still they were guessing and didnt know what they were talking about.

 

[voipio]

Toe and camber would be the two settings that affect tyre wear evenness the most. AVI_8 beat me to it.

 

[indy4x]

What make and model is your car?
Most cars have fixed castor and camber, adjustable camber with an eccentric nut is not unusual though on some cars.
Is the castor out due to worn components or a damaged/bent component
Shimming to get castor is not usual in my experience.
I would go to somewhere who specialises in alignment, Kwik fit would not be my personal choice.

Kwik Fit maybe not the 1st choice but the OP mentioned the vehicle has been lifted which may explain why its out

 

[minimutly]

Tyre wear is nearly allways down to toe in out. Camber is easy to see, and wth simple level type gauges, measure. If kwikfit were clever enough to accurately measure your castor they wouldnt be working at kwikfit...
Ignore their advice. Get toe in out checked, use a spir
it level or your eyes to gauge camber.

 

[AVI_8]

Kwik Fit maybe not the 1st choice but the OP mentioned the vehicle has been lifted which may explain why its out

Yeh which was why I asked what car he has, I’ve not heard of lifted suspension on anything other than modified 4 x 4‘s
Just like your avatar!
And cars with an upper wishbones don’t tend to have adjustable camber/castor

 

[rcx132]

What make and model is your car?
Most cars have fixed castor and camber, adjustable camber with an eccentric nut is not unusual though on some cars.
Is the castor out due to worn components or a damaged/bent component
Shimming to get castor is not usual in my experience.
I would go to somewhere who specialises in alignment, Kwik fit would not be my personal choice.

It's an Isuzu Trooper. I was surprised but the castor and camber are adjustable, see screenshot below from the workshop manual.

 

[rcx132]

I found a way to line up the laser level and checked the castor, it's the exact same on both sides so I don't get the Kwik Fit readings. Just the camber is out, which is likely due to the suspension lift.
The car was pulling hard to the left which is why I started checking all this. I swapped the left and right wheels and now it pulls to the right, just enough to offset the crown of our left side roads, perfect.

 

[Seadog]

Eddie China went through checking and adjusting caster when he repaired the orange on wheels.

 

[jsf55]

I found a way to line up the laser level and checked the castor, it's the exact same on both sides so I don't get the Kwik Fit readings. Just the camber is out, which is likely due to the suspension lift.
The car was pulling hard to the left which is why I started checking all this. I swapped the left and right wheels and now it pulls to the right, just enough to offset the crown of our left side roads, perfect.

Have you checked you have the same size tyres on all four wheels

 

[8ob]

You can borrow this on a break it or lose it you replace it basis.

 

[rcx132]

I once went to kwik fit for my exhaust to be replaced and they advised that I need the tracking adjusting on my cars rear suspension....... its a beam axle, there is no adjustment on it, its a solid piece of metal.... I had recently rotated my tyres so the tyre wear may have looked a bit odd, but still they were guessing and didnt know what they were talking about.

A beam axle could be bent. My old textbook says toe and camber on those can be adjusted by heating the metal ! Doubt anyone these days would know how to do that.

@8ob thank you. My laser level seems to be doing the trick now. Just need to older some shims.

 

[voipio]

I found a way to line up the laser level and checked the castor, it's the exact same on both sides so I don't get the Kwik Fit readings. Just the camber is out, which is likely due to the suspension lift.
The car was pulling hard to the left which is why I started checking all this. I swapped the left and right wheels and now it pulls to the right, just enough to offset the crown of our left side roads, perfect.

Hard cornering scrubs the tyre edges on the outside of the turn. If the hard cornering is predominantly in one direction, the resultant tyre wear could lead to the steering pulling.

 

[AVI_8]

I found a way to line up the laser level and checked the castor, it's the exact same on both sides so I don't get the Kwik Fit readings. Just the camber is out, which is likely due to the suspension lift.
The car was pulling hard to the left which is why I started checking all this. I swapped the left and right wheels and now it pulls to the right, just enough to offset the crown of our left side roads, perfect.

Sounds as though you‘ve found your problem, presumably uneven tyre wear?
Your screenshot doesn’t work on my iPad
If your rear tyres are evenly worn maybe put them on the front and go to ab alignment centre (specialist)

A beam axle could be bent. My old textbook says toe and camber on those can be adjusted by heating the metal !

You can’t bend suspension components, what textbook are you referring?

 

[rcx132]

Sounds as though you‘ve found your problem, presumably uneven tyre wear?
Your screenshot doesn’t work on my iPad
If your rear tyres are evenly worn maybe put them on the front and go to ab alignment centre (specialist)

You can’t bend suspension components, what textbook are you referring?

A very old US textbook, like from the 70s. It's the beam that is heated, not the links.
Yup I may have found the problem but I'll still correct the camber, it looks stupid how it is.

Hard cornering scrubs the tyres on the outside of the turn. If the hard cornering is predominantly in one direction, the tyre wear could lead to the steering pulling.

Makes sense, I corner way too hard on roundabouts so the tyres are worn on one side.