MOT and four wheel drive

[voluptua]

My Yeti is the first four wheel drive car in a long time.  And the others have been centre-diff land rovers rather than Haldex type.

 

Are there any special cautions to be aware of when booking a UK MOT test?  I'm wondering if the standard one-axle roller text of the brakes is OK.

[KBPhoto]

When I took mine in for an MOT this year, my usual garage had to take it to another garage that had equipment for testing 4x4 in order to complete the test.

I've no idea what or why, but suspect he only equipment to test single axle drive vehicles.

[KenONeill]

As above, you either need a 4x4 set of rollers or it at least used to be possible to do a road test rather than a roller test.

[Llanigraham]

Most MOT stations do not have 4x4 brake test rollers so they use a TAPLEY Meter on a short road test. 

Being in an area with lots of 4x4's most of the testers have them around here. One garage has a long enough frontage that they can do the test on that.

 

http://www.tapley.org.uk/

 

Basically it is a decelerometer

Edited 11 November, 2015 by Llanigraham

[voluptua]

Thank you for these replies: I'm now armed with the information I need.

[mannyo]

Mine has always had the brakes tested on the road using a tapley meter, but mine is full time 4WD and not Haldex.

[speedybenny]

hi, mot brake test can be done on single lane testing equipment by turning off the ignition switch before the rollers start,as the haldex system is electronic. turning off the ignition diconnects the drive to the rear wheels at the haldex  so one axle can be done at a time ,

[Falmouthboy]

hi, mot brake test can be done on single lane testing equipment by turning off the ignition switch before the rollers start,as the haldex system is electronic. turning off the ignition diconnects the drive to the rear wheels at the haldex so one axle can be done at a time ,

Daft question, but surely if you turn the ignition off the engine won't be running so the servo won't work?

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[countryboy]

I would guess they'd drive the car onto the rollers, turn off the ignition and use the residual vacuum in the system to get the brake pressure.

Ian 

[speedybenny]

your right countryboy and when moving to other axle car is started so recharges servo so has vacuum for the test .gets a bit of a problem when its a dsg with electronic handbrake(as v w tiguan & the new superb when it gets old enough)but still can be done.

[Llanigraham]

hi, mot brake test can be done on single lane testing equipment by turning off the ignition switch before the rollers start,as the haldex system is electronic. turning off the ignition diconnects the drive to the rear wheels at the haldex  so one axle can be done at a time ,

 

Err. No it can't!!

You turn off the ignition you no longer have any servo assistance, plus the Haldex is still connected.

If you did that to my car I would be talking to my friends at DVSA VERY quickly!!

 

And how would you do that with a Land Rover?

[trundlenut]

Err. No it can't!!

You turn off the ignition you no longer have any servo assistance, plus the Haldex is still connected.

If you did that to my car I would be talking to my friends at DVSA VERY quickly!!

And how would you do that with a Land Rover?

You will have servo assistance until the vacuum is depleted. Also the Haldex clutch won't be engaged, but it may depend on which version of Haldex is fitted.

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[James@RRG_Skoda_Rochdale]

Err. No it can't!!

You turn off the ignition you no longer have any servo assistance, plus the Haldex is still connected.

If you did that to my car I would be talking to my friends at DVSA VERY quickly!!

And how would you do that with a Land Rover?

Most cars have special test procedures that are to be followed during an MOT test. The governing body in charge of the test at that time will release and approve ways of testing certain systems. many moons ago VOSA deemed that how speedybenny has described was an appropriate way of testing Haldex awd systems, this was to accommodate the likes of the mk1 audi tt.

Haldex is an electronically operated semi permanent system, you can remove it's fuse and completely deactivate it if you so wish but as already pointed out - turning off the ignition will inhibit it's function and allow unspent servo pressure to operate the brakes for that part of the test.

The DVSA will no doubt give you the same answer if you choose to contact them on this matter.

as for the landy - if in doubt most would use the decelerometer.

Edited 11 November, 2015 by therevrendjr

[Ryeman]

You will have servo assistance until the vacuum is depleted. Also the Haldex clutch won't be engaged, but it may depend on which version of Haldex is fitted.

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The servo has a one-way valve that makes it a vacuum 'accumulator'........a reservoir if you like.

It'll give 2 or 3 applications before you're dead.(((((

(Sorry for the egg-sucking)

[trundlenut]

The servo has a one-way valve that makes it a vacuum 'accumulator'........a reservoir if you like.

It'll give 2 or 3 applications before you're dead.(((((

(Sorry for the egg-sucking)

Exactly, which should be sufficient

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[Llanigraham]

My local garage says that he will only use the Tapley Meter on any 4x4 where there is any connection between front and rear axles, such as a Haldex, VCU or similar system.

He says that this is allowed in the MOT Testers Regulations.

He is not allowed to remove any fuses to disable any system.

 

And in general he reckons that a brake test needs more than 4 applications and therefore this would evacuate the reservoir, plus each application can reduce the assistance available.

[James@RRG_Skoda_Rochdale]

I used to work somewhere that had brake rollers capable of testing any type of 4wd system, we worked on many subarus. when the vehicle was driven into them and they were triggered the rollers would turn in opposite directions thus allowing the diff to rotate without causing damage.

[fordfan]

Most cars have special test procedures that are to be followed during an MOT test. The governing body in charge of the test at that time will release and approve ways of testing certain systems.

I wish!, there is no vehicle specific information available on the new computer system as the DVSA have to pay for it.  We're lucky if we get brake testing weights and even luckier if they're accurate, I had a Focus the other day that gave a weight of 9Kg.

 

I follow the rule of thumb - 'If in doubt, get the Tapley out'.

 

Smart cars are should be roller brake tested with the engine off and then using the engine to replenish the vacuum.

[speedsport]

My Skoda dealer will only use the Tapley Meter on 4x4's of any make during brake tests. Sensible people!

[Brijo]

(^^ Good to see you here again, John!)

[4 wheel driver]

Progress update:

In response to suggestions:

1 Car inspected on garage ramp. 

2 Weights on prop shaft amidships. No marks to indicate any missing. 

3 Test drove  about 8 miles with mechanic and myself driving. 

Gave the car a good work-out and there was no sign of judder.

4 Agreed to take car straight in when symptoms re-appear.

Intermittent nature of problem rules out Haldex and Prop-shaft, in his opinion.

Mechanic wonders if it could be ABS fault.

Will post any developments if and when!

Thanks again for all responses.

  

[Rustynuts]

8 hours ago, 4 wheel driver said:

Progress update:

<Snip>

 

 

Did you post this in the wrong thread?

[Ootohere]

Like here.

http://briskoda.net/forums/topic/473543-juddering-at-60mph-and-above

 

[fuzzybunny]

Hi All,

Just have my 4x4 MoT done last week on a rolling road rig and passed OK

I didn't see it done, (and I know I should have asked, doh!), but I'm assuming they use a similar system to this one in the video.

They did quote the figures for front a rear brakes so assuming they couldn't have used a Tapley.

Hope this helps, Cheers

 

 

[Llanigraham]

The MOT Testers Handbook says they should use the Tapley meter. Using rollers is considered unsafe and insecure.