This is what I've been wondering. Is it possible that all the problems seen from the crank pulley are due to faulty installation by an amateur?

 

But in my car's case I believe its a tranny related issue. The fact about the shifts and the ecu not keeping up. Not a problem with the installer as my installer has probaly done more crank pulley installs then anyway.

 

Bump. Come on folks, get your ballot in!

 

yeh this is understandable. This probably isn't too bad a fault to have, its the vibrations caused by an undamped pulley that i think is the serious problem with crank pulleys

 

19% Alta S/C with 0% alta light weight crank
Belt Snapped after about 20,000mi. after missing a gear taking it to redline and beyond. The alta crank pulley was trashed after the idler pulley limit stop snapped clean off, i replaced the belt and now on the second 0% alta crank pulley. I inspect the belt frequently and have replaced it twice since the incident. Seems to me with a better limit stop there would only be the problem of snapping belts.

 

... Is that a SC pulley or crank pulley problem?

 

I have seen a idler pulley limiter being sold in a few places for about $25. Looks like this might be a good invertment.

Randy
m7 Tuning

 

How come no one has an Alta 3% pully?
It seems like the max was 2%. What do I need to learn to understand this more?

 

Or the 1% or very few of the 0%. Reason being is people either go big with 2% or 4%. So they get roughly a 17% or a 19% reduction with a 15% pulley.

 

I have the JCW package (no idea about the SC pulley). Any recommendations on whether or not to get a crank pulley? What size?

 

This question can be answered by many folks in many different ways.

From what I have read, the common answers are this:

JCW pulley size is 14-15% reduction (depends on who you ask)
People usually do a 2% reduction pulley on JCW cars from what I've seen.

 

or they go for a 17% pulley instead. and keep the stock crank.

 

I have an ET 15% reduced supercharger pulley. I had it installed by the man, the myth, the legend, Randy Webb at one of his patented pulley parties in early November of 2005.

Not long, mind you, but there have been no problems so far!!! I'm more than satisfied with it.

Randy showed me both the ET and an Alta at the same time, and they were identical in every way, except the logos engraved on them.

 

there's one in every crowd they say. Well, here goes:

35,000 mi on car now.
at 3500, Randy inst. 15% pulley, no problems at all
30,500 installed 2% Alta pulley. Non-Mini guy did it. There was immediate slight vibration/rattle and roughness at low revs, like at takeoff or lugging engine.

32.500 new belt tensioner installed. (on warranty).This reduced the vibration a little. but it was still there and a concern.
34,000 I personally Ireinstalled a 2005 stock crank pulley that Randy gave me.

This made the car smooth like it used to be. I prefer the smoothness over the slight performance improvement.

No "problems" in that no breakdown , and maybe the mechanic tweaked the tensioner assembly since he probably did not have the proper tool to reduce tension on the pulley. Maybe my car is just sensitive and it does need the damper. I really wanted the Alta Pulley to work out.

BTW, I have the MTH program which has the quick return to idle, so the additional mass of the pulley does not keep the revs up like the stock ECU does.

I have OBX header (installed after stock crank pulley re-installed) and it does cause some roughness and resonance at low revs, but it is not as intrusive or vibrational in nature. The OBX makes the car really sound good and gives it a little more pep above 5,000.

 

Your dealer didn't give you any flack about the aftermarket crank pulley???

 

M7 16% and Alta 2% no problems at 7500 miles. Did the conversion at 2200 miles. Also have an Alta 0% crank pulley available for sale 300 miles on it perfect shape. $100 with free shipping. Pics available. PM if interested.

 

when fitting the crank did u have to 'run in' the crank? or no.

and is running a 15/2 set equivalennt to runnig a 17/0 setup? randy rekons 15/2 is good but is that the same as 17/0?

 

I haven't heard of anyone having to run-in any pullies.

Randy reccomends a 15/2 combo because it is easier on the belt. A 15/2 combo is very close to 17. I think I saw someone do the math and its like 16.8%.

 

I try not to get into any run-ins with animate or inanimate objects.

No issue with warranty. Shouldn't be a problem anyway since smaller pulley = less tension on tensioner.

It may be I'm just sensitive about changes to the car. I do suspect that the vibration/harshness resulting from the solid crank pulley would affect the accessories (supercharger) driven off the belt if allowed to persist too long. I don't think it is a matter of crank bearings or engine balance.

I don't think the pulley was defective in any way. It just didn't wonk for me.

 

I've got the 15/2 combo and love it. good bump up in power and quick response. No problem with it

 

I think you missed a couple of things, brand and mileage.

 

And how hard u drive the car (redline etc)

 

Alta/Alta, Drive hard 50% of the time in traffic the other 50% and just under 10K on both

 

Link to post

 

Thanks for posting this over here as well and helping get the word out. We feel that if you are running custom software with a higher rev limit you should think twice about a lightweight pulley . I get into the 7k range now and then with no issues but for those of you really pushing it we would caution you with regards to any un dampened pulley.

Randy
M7 Tuning