Recently put an Alta 2% crank pulley with a 15% supercharger pulley. Have only been driving w/mods for a week, but have noticed a "Vibration" or "Shuddering" when accelerating in 2nd gear from about 2500-3000rpm.

However, I can't necessarily attribute this to the 2% pulley, because I also had new springs put on, sway bar, CAI, and polyurethane engine and transmission bushings on as well (all Alta). So it may be that there is a little vibration form the pulley, that is being transmitted via the increased stiffness of the other parts, or more likely, the engine vibration that existed before isn't being absorbed like it used to by the stock engine mounts and bushings.

Or, rather, I would have to start removing parts back to square one and add them in piece by piece to determine what may have caused or is transmitting the vibration.

The interesting part is it only happens in second gear, and only if I am gentle with the throttle. If I shift into second with a more wide open throttle, the vibration doesn't occur.

My car is an '05 MCS with 23k miles. I drive aggressively, but not to redline very often. I haven't had this set up long enough to talk about longevity problems with the engine or oil pump. Either way, the pulleys have changed the character of the car and made it much more fun to drive (not that it wasn't before). To quote: "My car goes to eleven."

Brian

 

Hi Brian,

Thanks again for the business and the opportunity to do the installation for you as well.

For 100% your vibration is related to the upgraded motor mounts and not to the other items. If you hate it let us know the next time you come up to have something installed and we can check the mounts etc. But that is a common byproduct of the near solid motor mounts.

PLEASE feel free to call me or my staff at anytime to help with this or anything else! Chat soon!

 

Thanks Adam! I appreciated the chance to come visit your facility and have really enjoyed the work Alta has done for me.

Just to be clear, my post wasn't intended to be a complaint (if it was taken that way), more just an observation. I figured the vibration was most likely due to the motor mounts. I was hopefully more making the point that when making so many changes at once, it can be hard to "pin down" the cause of new vibrations, and the only real way to isolate it to a specific part is to add one by one, and in combination until the problem is found.

Sorry if I muddied the waters, but a post like this was extremely helpful in helping me research and decide on which mods, and how they would affect my car, so I wanted to "give back" as it were.

I'm hoping to come up again for your airshow event. One or two more things to complete my dream car.

Brian

 

Nope I knew it wasn't a complaint at all. Just wanted to be sure I addressed the concerns for you and others that might have been reading.

Thanks again and see you on the 9th!

 

One of the things I've been interested in is the difference between a JCW SC pulley with the Alta 2% CP versus a 16% SC Pulley with the same 2% CP.

I'm sure the ratios are different as I've heard he JCW SC pulley is approx a 11% pulley.

Any one have more info and an idea of what kind of improvement with changing my 11%JCW SC pulley with the Alta 16% SC pulley?

 

I am sure someone will correct me if I am wrong, but the general consensus is that the OEM JCW pulleys are 14% smaller than the regular Cooper S. So a JCW + 2% should be equal to that 16% reduction. When we have local clients into do lower pulleys on JCW cars we generally do 2 or 3% to get close to that 17% total reduction.

Hope that helps! Let me know!

 

I thought the JCW was 11.8% or something..... who knows

Some discussion about it...
https://www.northamericanmotoring.co...CW+Pulley+size

 

I'm pretty sure I read 11.4% or something like that. I think its been shown that it is not 14%.

 

Good Grief!!! I've been researching, reading, asking and now PURCHASING pulleys. Is it possible to get a clear answer as to whether or not to install a +2 CP with a 16% SC Pulley? Do I need to change the sizes of the other pulleys such as the A/C, Oil Pump(?) and Alternator? We've all read about the oil pumps failing, etc. but, those always seem to be "I heard it from a friend who heard it from a friend who..." (I know: "heard it from another you been messin' aro-hound") Some manufacturers say that anything over a 15% reduction of the SC Pulley is a waste because of over-revving and THEN we see someone who's running 19% with a 2+ Crank Pulley who hasn't been able to wipe the smile from his face for over 50,000 miles. I'm sorry, but I've become so frustrated with vendor's claims about their products superiority over their competitors and then reading about customers who couldn't be happier with that competitor's product . So, if you'll forgive my ignorance, here's my question; Is there a Harmonic Balancer available for an aftermarket lightened, 2% over-driven Crank Pulley? Would that solve the problem of accelerated wearing out of various parts due to vibration?
Thanks to all of you, I wish I could count how many times I've gotten GREAT advice on this Forum.

 

I'm glad you posted this because I'm also very confused with what size S/C Pulley and whether if I should touch the CP at all?

Some seem to be fine with the car since installation and others complain about other parts virbrating etc.

 

My car has 115,000 miles with 16% S/C pulley and 94,000 miles with both the 16% and 2% pulleys. I'm now at 117,000 miles and still going strong. The MidCal MINIs club members in Central California are racking up a lot of miles with this combination without any problems. We just keep on smiling.

Steve

 

I'm assuming from your gallery that you drive your car fairly aggressively. Also, judging from the pics, you've used a LOT of M7 products...I really like the quality of everything I've gotten from them. The day before yesterday, I expressed my concerns to Shelly who assured me that there had been no problems with the 2% combined with the 16%...THEN I talked to Peter who again assured me and said, "I'm not going to force you to buy it (although I already had it in my possession!) if you don't want to install it, send it back and get something else". He was VERY cool about it and said that unless I was running my car at 7500 RPMs for extended amounts of time, there's nothing to worry about. I've got 114K on this car and I'm nervous about "unbalancing" anything at this point...BUT that statement about "7500 RPMs" is starting to make a little more sense to me. Steve, thanks for your reply..do me a favor and convince me to install the pulleys...I mean I DO already own them and it's going in the shop tomorrow. How much do you love YOUR car?

 

I'm keeping my MINI forever so I'm not going to put anything on to break it. My rev limit is 7200 rpm and I hit the limiter all the time. I've driven turbos most of my life and I tend to keep the rpms up above 3000. I've installed dozens of 15% and 16% pulleys and almost everyone comes back for a 2% crank pulley. You are beyond the supercharger's published lifespan so you may have to replace it sooner rather than later but the pulleys won't be the root cause, age will. The rest of the engine will be fine.

Steve

 

I have a jcw and also wonder about the 11 or 14% thing. I also have a 3% crank pully that was installed be the good "dr. Steve" , and I love it, can you say torque.
Yes he does know what he is talking about. There are many MINIs modded out of Custom Mini Shop and most have combo pullys, one recently repaired because of an off brand pully.

 

So would anybody think that if I installed a 17% SC puelly with a 3% CP I would be pushing it? I will be leaving the rev limiter stock.

 

There's a point where you generate more heat than power and you spin the supercharger way faster than it was designed for. Where those points are is open to debate (much debate). I just have a lot of experience with the 15%/2% and 16%/2% combos and have not seen any issues. If I had the time and money I would like to test everything on a dyno and do long term endurance testing. Oh well...


Steve

 

i agree with Steve the 15% plus 2% combo works well. the guys that have the 19% plus 4% combos are going to start to see problems long term i think. and really if you did a bunch of dyno test you would find that a 15% with a good tune will make more power than the 19%, give better belt wear, and last longer.

 

Webb 15% sc pulley - +10k no problems
Webb 2% crank pulley - 2k no problems

 

Alta 15% SC pulley
M7 2% Crank pulley

Installed by Webb about 2 1/2 yrs ago (?) at about 14k. This past April, at about 29k, had a new shorter than stock belt installed, supposively the correct size for the pulley's I have. It shredded at Watkins Glen on Monday afternoon on the warm up lap of my 3rd session, replaced Tuesday with a Napa stock size belt. Don't know why it failed as the cars ben autox'd 2-3 times /month since then plus a two day track event @ Watkins Glen in May....

 

Alta 17% sc pulley
Alta 2% crank pulley

Blown Motor (see gallery) on lap 300 or so of the Nordschleife - don't think it was pulley related though. Looks like #1 con rod snapped. Possible factory defect?

Also, note the burnt (black) pistons/rods. Looks like catastrophic failure of the #1 con rod. All the oil went out the cylinder as far as I can tell--spun bearing (big time!) on #3 (pic says #2 but it's #3).

Rebuild will have an Alta 0% since the 2% crank pulley was bent somehow when the motor grenaded on the Nordschleife. New motor's in--just waiting on the new pulley from CMS.


EDIT: Anyone who's had a oil pump failure take their motor apart? Any ideas for why my #1 con rod snapped?

 

I weep for you......

Wish I had gotten there when I was stationed in Stuttgart for three years.

 

I have a 19% and a 4% crank. The crank pulley isn't installed yet, but I am highly likely to put it on. I do have a plan B 06 supercharger if stuff hits the fan. I have calculated a couple of figures regarding the supercharger (M45) flow rates along with pulley sizes, and it looks like I wont be in danger until I exceed approximately 5101 RPM. I can handle the temp issues beyond that point with my intercooler setup. 5101 RPM is the exact engine speed needed to meet the 14000 RPM "limit" of the EAton M45 when a setup I am looking to perform, is actually instilled. Its the same as a stock setup at 6573 RPM. So if stock pulleys exceed the 14000 limit of the eaton M45 before redline, and people rev to 8k with a 15%, what bad can it be revving to 7000 with a 23% reduction (all water pump issues aside)

 

Gulp!

Coming to the Glen in October?

 

Any failure related to 2% light crank pulley + 15% reduction s/c pulley to date? It has been badly debated before and lots of thrasing thrown that it is not a good idea. There must be lots of miles from those who have them by now.

 

Before I disconnected the battery and left my baby in the garage back in Oct, she showed 43,000 miles on my odometer. I had a 15% sc pulley and 2% cp installed when she had around 22,000 miles on her. I'm an aggressive driver and the only problem I can see with the 2% is my clock runs fast. It takes a few weeks, but I always have to reset it and knock off almost 30 minutes. That, and sometimes the exhaust tone gets a little violent when idling with the ac on, but I very rarely run the ac, so it's not a concern of mine.