Harmonic dampers/crank pulleys.

[paulmanta]

I have a slightly hotted up V8 rover engine, I want to know what options are available to me with regards to tidying up the front crank pulley, At the moment its got the SD1 pulley on it with three different belt slots and a metal plate thing bolted to the front.

I have no Air con, no power steering and only one alternator.

I want a smaller neater set up but am a bit concerned about mucking up the balance of the motor, does this matter ? will it do bad things ? am i worried for nothing.

Can i make a nice new pulley on my big lathe and drive on ?

[katanaman]

You can make other pulleys so long as you get it balanced but the main part of it is a damper (two parts bonded by rubber) that you probably cant make. This is important and has to be there or your crank can snap. You can remove the original pulleys that you don't need to shorten the setup if belt position allows.

[ppyvabw]

Physically speaking, what does the damper do? If the crank and stuff is balanced, why would the crank snap if the damper wasn't there?

The only reason I can think of is because you have the heavy flywheel at one end and if you had nothing at the other, and revved up quickly there might be a suddden torsion shock effect because the rear is heavily loaded, but the front isn't (I.e, it dampens the shock when the front cylinders fire). Is that why? Although the weight of the damper is minimal compared with the flywheel.

Is there a piece of rubber in there? I don't remember the rubber bit when I put my engine together lol, it was just a solid piece onto which the pulleys bolted on.

[katanaman]

Harmonic Balancers
Harmonic balancers, vibration dampeners or torsional dampener are used on an engine to stop or disrupt a vibration caused by the crankshaft. The vibrations give off a harmonic frequency and the harmonic balancer, made of both rubber and metal, is tuned to cancel out those frequencies, specifically. Since the crankshaft has to twist every time it rotates, its gives off a harmonic frequency, and the harmonic balancer helps to control that twist and the vibration. The harmonic balancer serves a second purpose, as well. It helps the engine by adding weight to the front of the engine, which allows it to runner smoother. http://autoparts.lifetips.com/faq/13069 ... index.html

Not the best description but its late lol and yes there is rubber in there.

[paulmanta]

I see, so me milling up a lump of alloy to make a nice new compact pulley will do the engine no favours.

dammit !!

Is there perchance a company who sell nice shiny new pulleys with the rubber damper ring ? this thing on the front of the motor looks like a blind man designed it.

Thanks for the info so far chaps, most excellent !

[katanaman]

There was a post somewhere on here about new performance ones but I think it was for 4.6 engines which are different. See if you can find it on a search as it might lead you in the right direction.

[ChrisJC]

A slightly better description:
http://en.wikipedia.org/wiki/Torsional_damper
but still quite unclear.

Chris

[kiwicar]

real steel have an sfi damper in their catalog, £183, er that is alot to make it pretty.
can't you just turn up some pretty ally pullys for the standard one?
bit of re jigging (and a few custom pullys) you could try and put a serpentine set up on it, now that would be neat.
Mike

[katanaman]

real steel have an sfi damper in their catalog, £183, er that is alot to make it pretty.
can't you just turn up some pretty ally pullys for the standard one?
bit of re jigging (and a few custom pullys) you could try and put a serpentine set up on it, now that would be neat.
Mike

That's the road I went, made up some custom alloy serp pulleys and it looks a treat. Probably not very cheap either mind you if you have to get them made. The billets alone cost me £50 and they were offcuts.