Bottom Pulley

[Paulm]

when car is running looking at the bottom pulley should it run true?. Mine seems to have a strange wobble. not from front to back more like up and down, as if the pulley has a high bit in it.

Paul

[dan_b]

This sounds awful familar - my brother's s2 had a cambelt slippage which caused the death of the engine, and in the post-mortem they found that the crank pulley was not true, it had an egg-shaped wobble in it, which eventually had caused the belt to jump and, well, the rest is history. I think Graham may have something to say about this too as he had a belt slip too? I'm sure there must be something that can be done about it though, plenty of engineers here - what's the cure?

[Graham]

If it runs untrue, it has either been fitted wrong or was a fault from new as the hole can only be off centre to cause an excentric motion, i will be clocking mine in when i fit the new one. My problem was the bolt came undone and caused the key to shear off and the crank to run in the pulley .
Graham

[Paulm]

looks like i need to investigate this

cheers lads

Paul

[puppetman]

i have a question. does the crank pulley differ from the 3b to the aan to the 7a? just wondering cuz im about to draw up my own design and have it machined out of alum. for my 7a. just curious.

[SteveH]

The crank pulleys do differ from 3B to ABY/AAN. Some use a 'V' belt for the alternator, while later cars use a ribbed belt. Best to check what you have/want before you get anything made up for the job.
If the front pulley isn't running true, it's either got a problem or had one in the past.
If the crank bolt isn't correctly torqued up, you'll end up with a hammered nose on the crank and/or a sheared woodruff key in the front pulley.
The front pulley isn't symetrical, due to it's role in the balancing of the crank. If it's loose it will hammer away at the crank until something breaks (usually the pulley key)
The only way to fix the problem if the crank nose is damaged, is to remove the crank and have the nose ground. Not easy or cheap to do

[puppetman]

thanks, i was wondering cause if i had one machined. so what your saying is that if i replaced the stock one with one made out of just alum. it will through the crank out of balance? i know it would make some more noise, but from what i understand it would not hurt anything. is this correct?

[caterpillar]

you have to change the bottom pulley to a new one,it have separert,the rubber layer are loos from the steel,and it is NOT cheap at the dealer

[SteveH]

The crank balance will be affected if you change the front harmonic balancer. By how much would be a guess. Everything attached to the crank, that rotates with it, has an affect on the overall balance. Changing to a lighter or smaller balancer shouldn't be a problem, if you plan to get the crank re-balanced afterwards.

[S2 jimer]

I've got this at the moment, it's putting loads of vibes through the car, having the crank looked at tomorow, hope it's not too expensive

Touching of the intercooler aswell, really not sure what it's gonna be, don't think the bottom pully's run true since i've had the car!!!!!!

[88GT-R]

I noticed my front pulley wobble a few weeks ago. just got the car, had cam belt change at 80 thou, and is now on 128 thou. Pulley does not run true on idle, but with a slight increase in rpm, runs true. Have removed alternator and PS belts to cherck movement in the pulley. No movement. Any suggestions, please.

John

[SteveH]

I noticed my front pulley wobble a few weeks ago. just got the car, had cam belt change at 80 thou, and is now on 128 thou. Pulley does not run true on idle, but with a slight increase in rpm, runs true. Have removed alternator and PS belts to cherck movement in the pulley. No movement. Any suggestions, please.

John

If the pulley wobbles at idle and runs true at higher revs, either the rubber damper in harmonic balancer is damaged or the pulley is loose. Either way, best to get it looked at before it costs a whole lot of £££

[88GT-R]

Are there any Audi specialists in the Salisbury area?

John

[SteveH]

Only person I know of down that way is Tom (Audiman) in Yeovil.

[phil2.016v]

Where's the best place to get a new pulley as i've noticed mine wobbles as if it is loose!