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Gunson type camber gauge
nearly done - 14/1/14 at 08:57 PM

Evening all , after 3 years on the road I feel that I really ought to get the camber angles checked on the Westy. Has any one had any experiences of using the Gunson ones that use a magnet to attach to the hub with a bubble to check the camber? Are they worth the money or tragically inaccurate.

Cheers, Sean.

britishtrident - 14/1/14 at 09:14 PM

The problem isn't accuracy more that it is totally impractical, the only way it can work is if the rear of the disc is unobstructed and available to attach it to.

Buy a cheap digital inclinometer (aka clinometer) or digital level off ebay.

nearly done - 14/1/14 at 09:19 PM

Forgive my ignorance but I thought it attached to the hub centre or to the brake drum (bolted tight to the hub) or am I missing something?

matty h - 14/1/14 at 09:33 PM

As said get a digital inclinometer a piece of angline drill two holes two hit the rim, put two bolts in them.
Put it on the ground zero it then on the wheel rim if you get 90 degrees it is straight up no camber.
Matty

big-vee-twin - 14/1/14 at 09:34 PM

Its because they do not stick to alloy wheels, however I have one stick it to the brake disc and it works fine.

When you do use it on the inside positive becomes negative and visa versa, apart from that no probs.


[Edited on 14/1/14 by big-vee-twin]

mark chandler - 14/1/14 at 10:01 PM

I use my ipad spirit level app and hold it against the wheel rim.

Before that I had a bit of metal that spanned the wheel rim with a bolt at each end so I could set it square with a bubble attached then used simple maths to set the bolts for the required angle, cost nothing and was very accurate.

You need the car on the flat with driver installed when setting up as these cars move about a lot.

[Edited on 14/1/14 by mark chandler]

chris-g - 14/1/14 at 10:23 PM

I have a Dunlop camber gauge, works well but it is a bit of faf.

Ben_Copeland - 14/1/14 at 10:43 PM

I've a magnetic one, luckily it fits through the spokes in the alloys, just.

dhutch - 15/1/14 at 05:32 AM

quote:
Originally posted by mark chandler
I use my ipad spirit level app and hold it against the wheel rim.

Really? And that gives a useful/workable/repeatable accuracy?

mcerd1 - 15/1/14 at 10:30 AM

the biggest problem with any of these methods is finding a bit of perfectly level ground to measure it on...

if the grounds not level then the measurements you get are as good as useless

40inches - 15/1/14 at 10:40 AM

quote:
Originally posted by Ben_Copeland
I've a magnetic one, luckily it fits through the spokes in the alloys, just.


That's the only way they will work, if you can't get it through the spokes you need this type eBay

chris-g - 15/1/14 at 10:43 AM

quote:
Originally posted by mcerd1
the biggest problem with any of these methods is finding a bit of perfectly level ground to measure it on...

if the grounds not level then the measurements you get are as good as useless


If you take the measurement on a flat surface that is always going to be the ideal scenario but you can still achieve very good results if you measure the slope of the ground and add or subtract (depending if the ground is sloping away or towards you) that from your readings. That is why the Dunlop gauge has two bubbles and dials at 90 degrees to each other, one for measuring the ground and the other for the camber measurement.

mcerd1 - 15/1/14 at 11:11 AM

quote:
Originally posted by chris-g
quote:
Originally posted by mcerd1
the biggest problem with any of these methods is finding a bit of perfectly level ground to measure it on...

if the grounds not level then the measurements you get are as good as useless


If you take the measurement on a flat surface that is always going to be the ideal scenario but you can still achieve very good results if you measure the slope of the ground and add or subtract (depending if the ground is sloping away or towards you) that from your readings.

that works if the ground is on a slope but it still needs to be flat.
and you have twice the error in your measurements
(you need to measure twice - therefore the error is doubled)



if the ground is uneven or curved (i.e. not flat, the camber on a road for example) it'll throw off the measurements

to give you an idea of the errors you could get:
10mm over 1m won't look like much
but is more than half a degree of difference (0.286°) which is quite a big error when your measuring something thats only ±3° or there abouts




obviously this can never be perfect - even the flattest surface in the world is only flat to a given tolerance

all I'm getting at is there is no point in using measuring device thats accurate to 0.000° if the datum surface is only accurate/flat to the nearest 1°



[Edited on 15/1/2014 by mcerd1]

chris-g - 15/1/14 at 11:30 AM

quote:
Originally posted by mcerd1
quote:
Originally posted by chris-g
quote:
Originally posted by mcerd1
the biggest problem with any of these methods is finding a bit of perfectly level ground to measure it on...

if the grounds not level then the measurements you get are as good as useless


If you take the measurement on a flat surface that is always going to be the ideal scenario but you can still achieve very good results if you measure the slope of the ground and add or subtract (depending if the ground is sloping away or towards you) that from your readings.


^^ but that way you have twice the error in your measurements


I did say it was a bit of a faf
Flat ground would be best and you have to choose your spot. My concrete screed garage floor is pretty level and I have used it a number of times with my road car when I have changed the wishbones and ball joints and it has always worked. The instruction tell you take measurements for the ground at the front and rear of the wheel and average them out.

[Edited on 15/1/14 by chris-g]

mcerd1 - 15/1/14 at 11:50 AM

^^ well at the end of the day a lot of tin-tops are built to ±2° or more

so a fairly flat bit of concrete screed is probably close enough
and probably still better than a lot of production cars!

but I think it helps to understand where the significant potential measurement errors come from
if you've got a long strait edge you could check the floor for flatness and slope, but if you want it really accurate the next question is how strait is you strair edge.... (this goes on forever and ever, the trick is knowing when its good enough )


I'd suggest that you try and have all your measuring devices and datum's about 10x more accurate than the answer you want
eg. measure to the 0.01° - but round the final answer to the nearest 0.1°


also as these cars have unequal suspension arms so things like the weight distribution inside the car (with or without the driver/passenger for example) and even the tyre pressures could affect the measurement - but this starts to get tied in with corner weights etc so they really need set before you go that far.....


[Edited on 15/1/2014 by mcerd1]

IanG1 - 15/1/14 at 07:33 PM

I downloaded an inclinometer app on my android smartphone, used this to check the results from the gunson camber gauge and wish now I hadn't wasted the money on the gunson lol