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D2 - Transmission Gearboxes, diffs, drive shafts. |
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Thread Tools | Display Modes |
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#1
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Quattro and MOT brake test.....2WD???
The 8 went in for its annual MOT today - another pass .
I never normally pay much attention during the MOT test and just let them get on with it, but today when they were doing the brake test I noticed that the rear wheels were not moving when the fronts were on the rollers, and vice versa when the rears were on the rollers. Is this normal? Shouldn’t the other set of wheels not on the rollers try and jump the car forward? I mentioned it to the tester and he said it’s normal. Shouldn't they raise a 4WD car? Surely it’s not good for the transmission?
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2002 S8 - Irish Green Pearl. Cat N (saved by the D2 Doctor ) 1988 E30 Coupe - Royalblau Metallic 2003 S4 Avant - Light Silver Mettalic 2016 S5 Coupe Black Edition - Ibis White |
#2
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Usually with four wheel drive cars, the tester will select a mode on the brake tester that rotates the wheels on each axle in opposite directions. This prevents the axle 'winding up' the centre diff and the wheels not in the rollers
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===SOLD===2002 Audi S8 D2 Final Edition (yes, really) in Avus Silver with purple extended leather===SOLD=== 2011 S5 Sportback in Phantom Black with black Super Sports leather, 9x20s, tech pack high, adaptive xenon plus, intelligent key, memory seats pack, sunroof, B&O, Audi Drive Select & quattro Sports Diff, DAB, parking system plus 2015 VW Golf GTI Performance Pack in Carbon Grey with black Vienna leather, tech pack (Discovery Pro nav & Dynaudio), DCC, factory towbar and retrofit RVC |
#3
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Thanks Adrian. I guess they wound up my diff today
Hopefully there’s no long term damage.
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2002 S8 - Irish Green Pearl. Cat N (saved by the D2 Doctor ) 1988 E30 Coupe - Royalblau Metallic 2003 S4 Avant - Light Silver Mettalic 2016 S5 Coupe Black Edition - Ibis White |
#4
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My tester used to drive my D2 down the lane to test the brakes as they couldn’t do 4wd on the machine
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#5
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Proper quattro with a torsen diff is absolutely fine on 2wd brake rollers as the torsen can easily accomodate the small amount of rotation. Haldex though, not so much, as the rear diff clutch would be locked up so it would either destroy the clutch or the diff. That would need the wheels rotating in opposite directions as Adrian described. I've never seen that happen though.
Most MoT testers I know just do a road test, some with a special weight-gyroscope sort of thing to measure the braking force, - my current tester particularly as he had to pay for a new diff on a TT quattro when they first came out! |
#6
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Similar to MJ's reply I think.
My tester puts a pendulum type of device in the passenger foot well and then goes for a test drive.
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Audi S8 D2 2002 88k mls Ebony pearl effect black. Grey interior. |
#7
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Inertia Tester is recommended by the Ministry for 4 wheel drive if the Test Centre does not have a 4 wheel roller.
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Ray at Wigan Pier 2014 A8L D4 4.0TFSI Gold (Sticker says "Beige") Can't leave you in a black smoke cloud anymore.. In progress, Nothing left to do. Gone 2004 A8 D3 3.0 TDI. Ebony Pearl Black (with little bits of other colours and glitter) |
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