UDP Help

[1993MTXSHO]

Install a larger snap ring.

While that seems promising, it's not 100% tested. Yes you know I have that done on my car as well, and am trusting it with a very expensive engine, so I'm not saying that's not the answer. But as long as you keep an eye on it, I see no problem in running one with or w/o a thicker snap ring.

 

[1993MTXSHO]

Is there any way to prevent it? Welding?

That would fix it yes, however you have to have it balanced after. Also by doing that it defetes the purpose of having a damper, you'll get the same crank harmonics that you get with the solid pulleys. Crank harmonics scare me, especially on an engine that already has bearing problems which is why I run the UD crank with the damper in it. I just keep an eye on it and see if I see any scrap marks around the c-clip (sure sign of the glue letting go and the pulley spinning within itself).

 

[gmorrell]

Is there any way to prevent it? Welding?

Welding would be highly counter-productive.

Typing this explanation for the umpteenth time...

The OEM Ford crank pulley is a harmonic damper*, it has inner and outer masses that are separated by a layer of rubber that is bonded to both pieces. Its purpose is to dampen torsional vibration in the crankshaft, it does this by trying to shear the rubber layer between the inner hub and outer ring and essentially turning the vibration energy into heat. Damping crankshaft torsional vibration helps the crankshaft live longer.

ASP made their crank pulleys/dampers with two pieces, similar to Ford, but they used large O-rings to provide the damping layer, and the O-rings aren't bonded to the pieces, it's just a friction fit. Look closely at the inner hub here, see the O-rings?



Unfortunately, all the power to drive the engine accessories has to be transmitted through this layer of O-rings, and eventually, they give up, and the outer ring slips with respect to the inner, driven hub. Once it starts to slip, it progressively gets worse until the outer ring starts moving about on the hub, and at that point, the whole mess is a paper weight.

* It is not a "Harmonic Balancer". One, there's no such thing, and two, if you use this term around me, I will put a horrible, disfiguring curse on your family that will last for 10 generations.

 

[expy916]

Now you guys got me all scared. I guess I'll just buy a SHOSource one.

 

[shopartsnw]

Just to be clear (and make sure Gary does not curse my family for 10 generations)

The SHO Source UDP is an Under Drive PULLEY. It is solid, so it is not a Harmonic Damper, and it definitely is not a Harmonic Balancer.

There are many lengthy discussions on the pros and cons of a solid aluminum UDP if you search SHOforum and the internet in general if you want more information.

 

[gmorrell]

Now you guys got me all scared. I guess I'll just buy a SHOSource one.

Not trying to scare you, just making you aware of the issues and compromises. ASP doesn't make UDP's for SHOs anymore for good reason, they pretty much all fell apart.

If you're not doing forced induction and pushing 2X+ factory horsepower, the SHOSource solid under-drive crank pulley will probably not make a difference in crankshaft life.

Chop wood.