hi all,

i am getting a whining/grinding noise form around the gear box area, if i am going along at 30 mph plus and engage the clutch or take the car out of gear completely i am getting a moderate grinding sort of noise.

when the car is in gear and driving at around 50 its more of a whine noise.

as i am slowing to a stop i can hear a mild judder noise, if that makes sense (cant feel any judder)

gearbox oil is good as is rear diff oil

unsure if related but....about a month ago i went for a mot and even though i questioned his use of the 2wd rollers he said it will be fine as he thought imprezas had a "double pump system"

any advice or tests i can preform to eliminate possible causes please??

thanks

 

An Impreza, afaik, should never go on 2wd rollers as it can munch the centre diff up. Sounds like thats whats happened to yours. Should be manually tested on the road in a suitable space (mine was anyway...)

 

I hope this is the case. I've never really given it any thought until now

 

if your impreza is put on a 2 wheel brake tester it WILL break the gear box any mot tester worth his salt should know that any 4wd car needs to be brake tested on the road with a tapley meter, to the op i would suggest you take it back and ask him what he's going to do about it?

 

They road test the brakes with a digital machine inside car that gives a braking reading.

they prob have shafted your box or diff the thick sausages

 

yeah i would go and ask them if they tested your car on the rooler dont let them and then i ask them what the hell they were smoking that day

 

I'm afraid to say sound like they've Fubard your centre diff mate

 

im a mot tester in the southwest and if i need to brake test a vehicle on the road as its awd we have a old style tapley meter.when a vt40 checklist is printed off vosa for the matched registered car it normally states only use a roller brake test tester if can switch off traction control/and/or safely test the vehicle without causing damage.!i would never use a standard roller tester on a awd/4wd even if its a audi with a haldex coupling.the tester is required to choose when the test is finished what sort of brake test was performed,roller/decelerometer on road or plate tester so there will be evidence at vosa to prove what type of test was used not just what you tell them.the difficult thing is to prove that the damage was caused at the time of the mot if thats what the noise is ??,hope you get it sorted bud

 

anyone know how i can test either box or diff to find which one is at fault?

is the cent. diff easy to change? i am a fairly competent DIY'er

 

my scooby has been on the 2wd brake rollers several times for mot. no damage. its only very slow for a couple of revolutions. similar to if you were cornering hard or if you pulled the handbrake on or locked up the front brakes during driving, neither of which damage the diff do they.

 

as a side note (might be worth mentioning) when doing a tight turn the front wheels have started to make a clunk-clunk noise.

 

if your mot station tests your car on a 2wheel brake roller they are doing it wrong, the fact that at least 2 wheels even 3 at some point are stationary and the 4th is being forced round will eventually **** you gearbox up end of.

 

its getting worse rapidly!

now sounds a bit clunky almost like un-oiled cogs turning.

someone said to me that it may be front diff?

i really want to get this solved soon, is there anyway of testing the components whilst on the car?

 

As mentioned above.

You need to report that MOT tester to VOSA for not doing the MOT according the tester's guidelines issued by VOSA. MOT testing is a very simple automotive task for a good mechanic and it really winds me up that incomptetant lazy fools like this still operate, ruining the reputation of good honest testers who know what they are doing, whilst also risking damage to customer's car. Worse still probably letting unsafe cars on the road.

AWD cars of any description MUST NOT be tested on 2 wheel rollers. The same rule applies for cars with limited slip differentials as well (LSD). And Imprezas have a rear LSD in addition to the centre coupling. So on both counts it should not be tested on 2 wheel rollers. As not only can it risk teh centre coupling, it will also put the rear diff at risk of damage as well.

So this MOT tester has f**ked up on two accounts. Its in the tester's manual, so there is no excuse. Its even on the MOT computer.

Proving the rollers has done damage is another thing though sadly. And if the garage has its own liability insurance (any good garage/mot tester will) you can bet your hind teeth their insurers will put up a good fight.

Technially it shouldn't do damage, but if the coupling or rear LSD is on it last legs (its an old car), it may well finish it off. If its a UK classic, both centre and rear diff will have viscous couplings. These are sealed for life and use their own oil, when they fail they leak mixing its own oil with the gearbox/diff oil. I don't think there is any easy way of knowing if they've failed or not, however a transmission specialist familiar with Subaru gearboxes and rear diffs may have a better idea.

 

interesting read.I've just had an MOT and brake test on a two wheel drive roller.
two questions.....
1. If i put the drivers centre diff control to the lock position would a 2wd roller be ok to use?
2. Is there a way at the MOT station of getting evidence of wht procedure they followed?

Cheers
Andrew

 

i run a garage , and do a lot of impreza's .. never never put them on brake tester as it'll **** them up.. take it back to garage mate and tell them whats happened , don't think it will do any good going to vosa as it was over 1 month ago.. threaten garage with trading standerds .. works a treat.... hope you get it sorted!

 

1. NO. Your car has a limited slip differential inside the rear diff in addition to the centre one, this works independantly of the DCCD setting

Cars with a limited slip diffs (LSD) (be it on the front or rear or middle) should not be tested on brake rollers.

2. You can observe the MOT being performed, as all testing station should have a viewing area. The MOT tester's manual is on the MOT computer, details of the exception for brake roller tests will be listed on there, but this should have already been pointed out to the tester during their traning (i.e they should check for a limited slip diff when checking wheel bearings).

 

thanks. I'm going back to the MOT station today for a retest. I'll bring it up and see what they say.
I was actully doing the braking myself as it was on the rollers and i was in the car.

Perhaps i will ask to see the computer manual details about brke testing.

I cannot believe i've never thought about this topic before!

 

I cant see how the center diff could be damaged by using the mot slow speed rollers for the short duration/load, it would leap off the rollers if the center diff was complaining.
Just look how the subaru unit works.


dipster

 

Correct.

 

you can will wind the diff up, which as said before, will end its life pretty quick and as SAID before no 4 wheel drive car should ever be tested on 2wd rollers, if they could be tested why is there tapley meters???

 

Hence why if the car is getting towed it must either be flat bedded or towed with all 4 wheels on the ground at a restricted speed and distance - as stated in the owners manual.