MOT question:4WD brake testing.

Some MOT stations can test permanent 4wd in the MOT bay. Others, like you say, have a portable brake tester. You'll just have to phone around although if it helps I know of one near Cambridge with a

John

Sleeker GT Phwoar ( snipped-for-privacy@bouncing-czechs.com) gurgled happily, sounding much like they were saying :

Certain vehicles should not be tested on a roller brake tester, eg vehicles with

- More than one driving axle permanently engaged

- Limited-slip differential

- Belt-driven transmission

- Brakes for which the servo operates only when the vehicle is moving

These vehicles should be tested using a properly calibrated and maintained decelerometer or a plate brake tester designated as acceptable for the statutory tests, see Sub Section 3.7 B, page 25, and C, page 26.

(Then look down that page to B. Decelerometer Test)

I'd certainly do some ringing around, but it seems to me that - with the ever increasing number of permanently 4wd cars about - any MOT station that refuses to touch 'em is on a bit of a loser.

Bit out of the way. I'm in the northwest. I'll check arround the local places, and maybe ask some of the second hand 4x4 dealers, see who they use.

Cheers for the advice about 4wd rollers. I knew 4wheel dynos in tuning shops, but never thought about them for brake testing even though the mechanical principle must be the same.

Cheers, I'll give that a look through.

You would think, wouldn't you.

Standard rollers should not be used in some 4wd applications. All mot stations have a decelerometer as part of required equipment, some may have 4 wheel testing facilities (I have seen only one)

If the station starts to use standard rollers, tell them not to, but all stations should be aware in any case.

mrcheerful

Cheers. Plan was to remind them when I arrived, not to use the rollers, as well as when I booked. Rather than take chances.

I'd say that 'permanent' AWD vehicles are so common all MOT stations will have the means to test the brakes. Ie, a Tapley meter.

Fun and games years ago taking my Bentley S1 for an MOT to the local while you wait MOT place. They stuck the front wheels on the rollers and got a big '0'. Those old R-Rs had a mechanical servo driven off the output shaft of the gearbox, so the rear wheels had to be turning for the fronts to work *at all* as the master cylinders were not connected to the brake pedal - only the servo. Which also meant you couldn't bleed the systems via the pedal. Weird but effective. Although only drums and a two ton car it would stop well from top speed. Big Jaguars of the time with a conventional servo and drum brakes were notorious for fade.

The place I take my gt-four does not have 4-wheel testing facilities. The first year I went there, the guy did the test on the 2-wheel rollers with no problems. Since I found out that this could cause problems with the car, I always mention the 4wd situation and he just takes it for a raod test. No probs and he comes back with a smile on his face : )

Regards, jim

That's the car I'm getting tested. An ST185 though, so it might make him grin a lttle, but not smile madly

Need to get the rear transmission mount (not the rear diffmount, thats been done already), and the rear strut tops done before I book it. The engine is flopping around and making the prop thump and bang. Thought it was the diff mount, but that didn't solve it, and it had a oil leak from the cam cover gasket which rotted the front ARB bushes, so pound to a penny, the transmission mount is gone too.

just what every mot tester loves, some-one telling them how to test the vehicles, we have a enough with the ministry, oppps sorry VOSA on our backs, the tester will be fully aware of the test procedure for a 4wd vehicle & if they are used to modern technology they might even have a digital decelerometer instead of the one that weighs about about a ton & sits in the passenger footwell !

That'd explain why they didn't follow proper procedure when testing the GT4 belonging to the other guy who contributed to this thread, then.

Peter

Or my land rover or my xr4x4. Never take chances, I say.

mrcheerful

Try the local bus garage, they usually do their own MoT's and have g-meters.

Thanks, will try that. Warrington buses are still run by the local council, so they should be reasonably priced. Also won't have any interest on failing stuff, as they won't be interested in fixing it.

I'm lucky that mine has apparently been tested properly until now. I just want to make sure it stays that way. The rear diff has some wear in it already, but I don't want them doing un-necessary damage.