Calibration of 4 Wheel Alignment Machines

Bikeracer1098 · 28 May 2018

A bit of a strange question, however anyone know how often does the 4 wheel alignment machines such as a Hunter etc need calibrating?

Matt Seabrook · 29 May 2018

Ours is done yearly and the lift twice yearly. So far it's never been out by more than a couple of mins.

Alex · 29 May 2018

Spec on the front toe is 5 minutes so that's 40% of your tolerance straight away.

rabbitstew · 29 May 2018

Interesting. I had my car fully setup at Centre Gravity a couple of months back and when I took it for its MOT earlier this month I happened to mention it to the MOT bloke. Anyway, he was keen to see what settings CG had used so after the MOT he stuck my car on their own Hunter rig to see.

I actually had a photo of the CG Hunter print out on my phone and the measurements my MOT places rig was showing were completely different. So either their rig was out of alignment or there is a degree of tolerance between them.

Matt Seabrook · 29 May 2018

alex yates said:
Spec on the front toe is 5 minutes so that's 40% of your tolerance straight away.

Sorry recheck your maths. On my car front toe is 5mins positive plus or minus 5mins so 0-10' toe in. 2 mins is 20% at worst if you can feel the difference of 2mins either way I'm sure any of the top motorsport teams would love to have you as we are talking about 0.1mm at the rim edge per 1'

:wink:

Interesting. I had my car fully setup at Centre Gravity a couple of months back and when I took it for its MOT earlier this month I happened to mention it to the MOT bloke. Anyway, he was keen to see what settings CG had used so after the MOT he stuck my car on their own Hunter rig to see.

I actually had a photo of the CG Hunter print out on my phone and the measurements my MOT places rig was showing were completely different. So either their rig was out of alignment or there is a degree of tolerance between them.

This is most likely down to the lift if its an MOT lift. Best bet would be to only use someone who specializes in alignment and has the lift and aligner calibrated.

:thumbs:

Alex · 29 May 2018

Factory front toe on a 996 C4 are 0 to +0 05' on my hunter print out.

Matt Seabrook · 29 May 2018

per side toe is the measurement of total across the axle :thumbs:

cheshire911 · 29 May 2018

I had my geo setup by CG a while back (996 Turbo) - the tyre wear readings at each service are emailed to him for comments if the settings might have moved and if they need checking - always checks and gets back to me stating nothing has moved at the rate of wear he has calculated based on my personalised settings.

The rate of wear on inner rears is consistent with the settings and mileage.

As Chris and Pete at CG only do this geometry/alignment and chassis tuning work, I'd guess their equipment is regularly audited for accuracy.

Matt Seabrook · 29 May 2018

As Chris and Pete at CG only do this geometry/alignment and chassis tuning work, I'd guess their equipment is regularly audited for accuracy.

I would be surprised if it wasn't.

Luke997 · 29 May 2018

Very relevant question - i had my alignment done by a northerly porsche specialist and the car didnt handle that well - I thought it was ok just wandered a little and i thought it might be a worn rack or bushes. Took it to another garage who found it had toe out at the front(!) their rig was cleary completely out

Alex · 29 May 2018

There's umpteen different things that can cause measurements to be out. Main one is usually operator error!

Matt Seabrook · 29 May 2018

As you can see from the calibration certificate below our is due next month. To have this the lift and data base done is going to be about £600 plus vat so I could see it getting skipped if things are tight. You can see that the calibration was close even after twelve months use. That said the equipment is well looked after as my lads know how fussy I am.

wjk_glynn · 30 May 2018

Matt Seabrook said:
As you can see from the calibration certificate below our is due next month. To have this the lift and data base done is going to be about £600 plus vat so I could see it getting skipped if things are tight. You can see that the calibration was close even after twelve months use. That said the equipment is well looked after as my lads know how fussy I am.

How do they actually check/calibrate your alignment machine?

Do they have a precision reference frame, use old fashioned strings method, or something else?

Thanks.

Karl.

Matt Seabrook · 30 May 2018

They use a theodolite to check the lift first to make sure it's still in spec and then put a test rig on using my targets fitted to it. The pc is then put in to a diagnostic mode and the readings are checked against the stored settings. If it's out the calibration is done in the software.

Like I said there is a cost implication to this and I could see some skipping this due to the costs involved. They also calibrate our GSP9700 vibration control balancer and our Auto34 leverless tyre changer gets a service as well. I look at it as if it was a car. Cars need servicing and the workshop equipment is no different if it's going to do its job.

Pro-Aligne know how to charge for the Hunter equipment but it is the best on the market in my opinion. I had to have one of the circuit boards replaced in the balancer this month and the board alone was almost £1200 plus vat. :roll:

wjk_glynn · 31 May 2018

Matt Seabrook said:
They use a theodolite to check the lift first to make sure it's still in spec and then put a test rig on using my targets fitted to it. The pc is then put in to a diagnostic mode and the readings are checked against the stored settings. If it's out the calibration is done in the software.

Thanks Matt.

Karl.

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