How does Awd cars needs to take mot test?
Discussion
Hi,
So I’m wondering how Awd / 4x4 cars get their mot done? I mean, if they have all time 4wd / awd, they cant be put on just two rolling dynos to measure, right? For example when car has torsen awd, like RS6 or RS5?
I always thought they have to sit on awd rollers where all wheels roll.
Probbably im wrong but just wanted to learn.
So I’m wondering how Awd / 4x4 cars get their mot done? I mean, if they have all time 4wd / awd, they cant be put on just two rolling dynos to measure, right? For example when car has torsen awd, like RS6 or RS5?
I always thought they have to sit on awd rollers where all wheels roll.
Probbably im wrong but just wanted to learn.
Crazy27 said:
normalbloke said:
Aka the Tapley meter.
Thanks a lot! Can it be tested on rolling awd dyno brake test function?
MG CHRIS said:
There is no such thing as a AWD brake rolling road for mots anyway Some 4x4 set ups can be used on brake rollers depending on the roller type however most just get a quick test with the tapely meter.
Yeah sounds about right, probbably like haldex or some other awd can be tested. I meant to say brake test on dyno for awd, is it a stup idea? Just asking lolgeorgeyboy12345 said:
A rolling road sounds a very expensive way of doing it if you can just use a tapley meter
Yeah this is for sure but also it can measure the power after tuning the vehicle, so double income but still power runs aren’t very expensive. Surely this needs to be decided carefully.Smiljan said:
Anyone actually know how it works?
Isn’t it just measures stopping power of the vehicle, not any precise like electronic ones. Only awd or 2wd rolling road systems can check which wheel has how much power. If im correct…Also, can anyone get a mot tester shop certificate only with decelrometer or tapley? Is that it? Or you need at least electric setup to test it?
My brake rollers have a 4wd function, basically you press to test ns brake and that wheel spins forward and the os spins in reverse. Then vies vers for the other side. Basically with the wheels going in opposite directions it's just spinning the diff, the only time this fails is when it's a 4wd with a limited slip diff.
4wd pickups (hilux, ranger etc) are just a standard thing to test as when there in 2wd they are rwd so test just like a rwd car. Defenders again are easily tested as the transfer box can be put into neutral therefore no wheel drive so can be tested in the normal manor.
Some test stations use a plate brake tester which is basically a spring loaded plate on the floor, you simply drive onto it and brake, the plate moves abit and records a reading. Luckily not used much anymore and very exciting if a brake pipe bursts as you drive on and brake!
A gradient tester can be used for parking brake which is basically a ramp at a certain angle (think it's 16 degrees) and the brake must hold.
The decelrometer or tapply meter is placed in the foot well or on the seat and you drive forward and brake to a stop, the meter records the force generated in the braking giving a reading, no imbalance is measured and you don't really know which brakes are working! The fronts could be fantastic and the rears non existent but if the meter says the required effort
4wd pickups (hilux, ranger etc) are just a standard thing to test as when there in 2wd they are rwd so test just like a rwd car. Defenders again are easily tested as the transfer box can be put into neutral therefore no wheel drive so can be tested in the normal manor.
Some test stations use a plate brake tester which is basically a spring loaded plate on the floor, you simply drive onto it and brake, the plate moves abit and records a reading. Luckily not used much anymore and very exciting if a brake pipe bursts as you drive on and brake!
A gradient tester can be used for parking brake which is basically a ramp at a certain angle (think it's 16 degrees) and the brake must hold.
The decelrometer or tapply meter is placed in the foot well or on the seat and you drive forward and brake to a stop, the meter records the force generated in the braking giving a reading, no imbalance is measured and you don't really know which brakes are working! The fronts could be fantastic and the rears non existent but if the meter says the required effort
If you don't say anything mot tester will put awd straight on roller bake tester which does one axle and wheels individually. I queried potential damage but they said diffs will sort it, for a short period that's probably true, it's pretty low speed test too.
One car I owned had a warning not to tow on one axle only, so I asked them not to use roller, instead they burnt around the car park braking. I think they should use a decelerometer for testing this not sure if they did. Looked like they had fun though.
There's a whole lot of mot info on the gov.uk website if you can be bothered digesting it.
One car I owned had a warning not to tow on one axle only, so I asked them not to use roller, instead they burnt around the car park braking. I think they should use a decelerometer for testing this not sure if they did. Looked like they had fun though.
There's a whole lot of mot info on the gov.uk website if you can be bothered digesting it.
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