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Cooper S Pulley Advice

46K views 17 replies 9 participants last post by  richbay 
#1 ·
I have decided to fit a reduced supercharger pulley onto my 05 cooper s - I did as much reading as I could and have decided to go for the 17% pulley.
I live in the UK and will only drive on the road (no track) - to start I will just change the pulley (+ plugs/belt), in future I may do the one ball / intercooler / remap - but just talking about the pulley for now.
I see there are lots of instructions on the net and I am pretty handy with a spanner so I am considering doing the job myself and wanted to hear from anyone who has already done it, how difficult was it, anything in particular I should watch out for - or should it be left to the experts ?
I would also like to know which pulleys people consider to be the best and why.
I would really like something that doesnt stand out too much, I think the Alta pulley is a bit obvious, the only thing I can find that keeps the original look is the JonSpeed pulley, they seem fairly cheap but they use an interference fit (think that term is correct) and must be heated in the oven - does anyone have any experience of these type of pulley?
Thanks :)
 
#2 ·
Never seen the JonSpeed pulley so I can't say. Either way you really can't see it once it is installed anyway so it shouldn't matter what you get.

As for the install I have do a lot of them and things that you are going to want to get are a good puller and make sure that you have jack stands and a good jack available to get the engine up. It would also be helpful to have the BMW tool to release the tension on the belt but if you are clever you can fashion something to do it. THe instructions on Alta's site are good or you can search for the ones made by Randy Webb.
 
#4 ·
Thanks DaFlake - I have a couple of trolley jacks and axel stands, they will send a puller with the pulley - I got an arc welder so I can prob make up something to release the belt tension - I did see one tutorial where they half removed one of the super charger bolts and just used a flat bar (http://www.kavsmotorsport.com/Mini-Cooper-S-pulley-install-instructions-howto.pdf) to release the belt. Can I ask if you removed the Air box as some say it is not necessary ? Also have you had any experience with the interference fit pulley ? Also how long did the job take you ?
Thanks Keano - I was actually looking at the KMT as well, as you say it comes in black and looks pretty close to the original, do you know anyone that has one ? Other than the look, my main worry is getting a good fit on the shaft - do those bolts hold it on ok ?

Thanks :)
 
#5 · (Edited by Moderator)
Thanks Keano - I was actually looking at the KMT as well, as you say it comes in black and looks pretty close to the original, do you know anyone that has one ? Other than the look, my main worry is getting a good fit on the shaft - do those bolts hold it on ok ?

Thanks :)
There are now alot of people running them with good results and no faults or problems with them. Another plus is that there is the option of having 2 'outers' so you can ran, for example, a 15% in the summer and a bigger reduction in the winter should you want to...

I bought one but due to a change in plans never fitted it - the craftsmanship of the pulley was excellent, just a shame I never got it on my car...

PM 'Fisher' on here or over on minitorque.com if you want more info on them - VERY good VFM ;) circa £65 ;)

Pic of the one I had :

 
#9 ·
Been running a 17% for a year now on a stock IC with 0 problems. I have heard that argument over and over and have yet to see any proof that it will actually be an issue for a car that is going to only be driven on the street. As the OP mentioned, he does not plan on taking the car on the track so a 17% pulley should be just fine.
 
#12 ·
I ordered the pulley/belt/plugs and a pulley puller today for delivery tomorrow - I also called my local metal shop and got them to cut two bits of steel to make a tensioner tool - if everything turns up and it doesn't rain, I will be fitting this on saturday - :)
 
#13 ·
De Flake
You say you have been running a 17% on standard IC for a Year with 0 problems.
In the long term I would expect you might find the oposite to be true.
Lets not forget the GP was supplied as standard with a larger IC.
So BMW Mini demed it as neccesary,or why fit it if not.
 
#14 ·
Chris, I am not going to argue this out again. Please post your proof that it is going to be a problem rather than posting an opinion. I know many people that have been running 17% pulleys on a stock IC for years with no problems. The recovery time on the stock IC has been proven and if you are not on a track it runs just fine. Heck I know folks that track their cars on a stock IC with a 17% pulley but I personally think that that point you are pushing the temp limits.

If you are going to bash the 17% as an option you need to bring proof. My proof is that myself and many others are running them with no issues. You opinion is noted but I am not buying it and this is my last post on this matter.
 
#16 ·
Well I tried today but I had a real hard time. I managed to get everything apart, my tensioner tool worked like a dream - I had the correct puller from minisport so I fitted it to the pulley and tightened up the big bolt in the middle, then the bolt snapped !! - I am seriously annoyed as I paid £70 for that tool, more annoying than that was the fact that I had the tool on the pulley wheel and couldnt get it off - I tried to undo the two bolts that hold the tool together, but it was already tight and under pressure, so the heads just stripped out.
I spent hours trying to get that thing off, eventually I drilled out the bolts holding the two pieces together, but my original pulley wheel looks a bit of a mess now - I have done jobs like this before without problems, but that pulley is on the supercharger shaft extra double tight and he does not want to come off -has anyone else had problems like this, are they all that tight (enough to break the big bolt) or is there another way to get if off ?
 
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