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you know the ones - the subarus etc breaking or burning out the centre diff when put on a set of 2-wheel rollers at mot time? i've heard ones also about the braking force applied ripping the spoked wheels off vintage cars? i'm taking my 7 to the cookstown station tomorrow and the manager told me that these rumours were rubbish/lies, and that 'there's never been a case of a car being broken by our equipment, in any of the branches'. i'm a bit worried about it tbh. I was trying to insist they get out one of those potentiometers (sp) but he insists there's nothing to worry about... reassure me!!  |
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Davenger
Club Retro Rides Member
It's only metal
Posts: 7,272
Club RR Member Number: 140
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I suppose, if the spokes break, then they were weak and needed replacing
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Last Edit: Apr 14, 2008 9:45:29 GMT by Davenger
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its the car brakes that provide the stopping power not the rollers, so if your brakes and tyres are strong enough to break spokes better its done on the rollers than on the road!!
as for centre diff damage, i can see it may have happened back when 4x4 cars were not common and someone made a mistake, but cant see any garage doin that recently, its not the sort of job given to the apprentice without supervision.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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Odin
Posted a lot
Posts: 1,406
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Surely if the spokes break on the tester then they would have broken doing an emergency stop anyway? I'd rather have them break at standstill in a garage....
As far as I know vehicles with permanent 4x4 shouldn't be put on the brake tester, but I would expect the MOT tester to know about that.
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^ Seconded. Surely the car can only exert the same braking forces as it would under heavy braking on the road? The brake testing machine wouldn't assist stopping in any way... what would be the point in that?! ;D
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The rollers are no more likely to bust your spokes than the road is. The spokes are only transmitting the retardation force generated by your drums, which wont change whether youre on rollers or on the road. As daveyboy says, if they bust its not the rollers fault!
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1974 Lancia Beta Saloon
1975 Mazda 929 Coupé
1986 Mazda 929 Wagon
1979 Mazda 929 Hardtop
1982 Fiat Argenta 2.0 iniezione elettronica
1977 Toyota Carina TA14
1989 Subaru 1800 Wagon
1982 Hyundai Pony 1200TL 2-dr
1985 Hyundai Pony 1200 GL
1986 Maserati 425 Biturbo
1992 Rover 214 SEi 5-dr
2000 Rover 45 V6 Club
1994 Peugeot 205 'Junior' Diesel
1988 Volvo 760 Turbodiesel Saloon
1992 Talbot Express Autosleeper Rambler
2003 Renault Laguna SPEARS OR REAPERS
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Apr 14, 2008 10:26:45 GMT
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don't worry about it - if the MOT testing equipment damages your car - sue the  off the garage involved |
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Someone just shot the elephant in the room. |
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Apr 14, 2008 11:26:50 GMT
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IIRC variomatic daf's used to be damaged by the rolling road I'm sure someone can elaborate at bit on it good luck with the test on the 7 tho
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'81 maxi (broken soon to be restored ) '88 Volvo 240 (Looking for some cheap 3spokes or Slotmag's and needs hitting wit da stick) B-)
'00 Omega tourer very slowly spoiling me :@
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Apr 14, 2008 11:40:26 GMT
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Cookstown eh? Where are you from?
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bigrod
Posted a lot
Posts: 1,654
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Apr 14, 2008 12:14:00 GMT
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Cars with LSDs can be damaged by brake rollers.
Don't quote me on it, but if there's a risk of damaging the mechanics of the car my sticking it on the machine then 'I think' the tester can road test it as an alternative.
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If I have to explain, you won't understand.
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Filthyjohn
Part of things
Currently on the road: 1/11
Posts: 705
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Apr 14, 2008 12:28:55 GMT
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The problem with Variomatic cars at the MOT comes about when they try to start it in Park, or put it in Drive with the revs above 1100ish. Noise and lots of clutch wear are the result, I've heard rumours of 340 varios suffering total clutch failure when loaned to garages unfamiliar with the system.
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'95 Volvo 945 Turbo
'87 Volvo 765 TIC
'75 Opel Manta A 2.0 16v,
'86 Volvo 360 turbo,
'62 amazon,
'67 MGB GT.
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Apr 14, 2008 12:48:19 GMT
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yeah if you have an LSD the car MUST NOT be put on the break test rollers... they must do an on the road break test!
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Apr 14, 2008 12:49:34 GMT
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I have personally seen a guy doing a roller break test on a subaru legacy. I have no idea if he damaged the diff or not, but he simply didnt realise it was 4wd.
Ive also seen a couple of scoobys being towed on spec-lifts. Again no idea whether they have removed the prop etc, or if its just ignorance/laziness on the part of the driver.
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1986 Panda 4x4.
1990 Metro Sport.
1999 Ford Escort estate.
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Apr 14, 2008 12:53:04 GMT
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A couple of people on scoobynet have had their centre diffs ruined by clueless recovery truckers. When my dad's old WRX threw a big end they sent out a spec lift, the guy said 'I cant take it, will send a flatty' and that's what happened! I can see how clueless driver + clueless recovery = broken centre diff as my dad didnt have a clue!
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1997 TVR Chimaera
2009 Westfield Megabusa
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Aaron
Part of things
Posts: 225
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Apr 14, 2008 14:40:02 GMT
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SurprisingSkoda,
The MOT guys here always double checked with me if the GTi-R was 4WD when I arrived at the centre, so never put it on 2WD rollers. They got the guy next to me to swap lanes one year. I think there's now a section on the application form that asks if the vehicle is 4WD so they can book you into the correct test lane.
Also, my brother's Rover was brake tested out the back of the test hall on one occasion, can't remember the reason why, just recall the tester giving it a real bootful down the yard before braking.
Aaron.
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1975 Toyota 1000 with 4A-GE (tweaked a bit)
1992 Nissan GTi-R (now sold after 17 years)
2001 Subaru Impreza WRX (remapped)
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Apr 14, 2008 15:34:10 GMT
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cant see why brake test rollers would hurt a LSD when giving them max power on the rollers at a rolling road don't do it any harm, even if the rollers power up to speed so they can test the brakes thats no different from a rolling road pushing your wheels round as they let them run down to test the loses in your power train.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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Apr 14, 2008 15:38:40 GMT
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I've been thinking about similar things regarding LSD's & MOT tests, surely it doesn't do them any good when the independant brake test is done? Locking one whell whilst allowing the other to still rotate, surely a road test is safer for the diff? Just a bit worried for when I fit my TRD diff (eventually..)
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Apr 14, 2008 15:50:55 GMT
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There are certain types of LSD that can't be roller brake tested, torsen being one and maybe viscous coupling. I've have heard stories of diffs being blown whilst on roller brake testers, but they could easily be chinese whispers
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Faster. Faster. Until the thrill of speed overcomes the fear of death.
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Apr 14, 2008 16:09:11 GMT
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so my cosworth viscous unit will not go on an mot roller?? is this only if they do one wheel at a time or what? can someone explain the possible reason or theory to why this could happen?
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Apr 14, 2008 16:13:56 GMT
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i'd forgotten they do one wheel stopped while the other rotates cos me mate has been taking mine to his test station and i havent been there with one for aaaaaages, your right I wouldnt stick any LSD on a brake test unless they run both wheels at once some types lock your whels solid if the speed difference or the torque running through them is to great, and a mig spec one would do the same.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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