I recently bought a lightened +2% crank pulley along with the alternator reduction pulley. I wouldn't have messed with this but last track day in the fall my serpentine belt disintergrated around red-line and sent the belt tensioner into the crank pulley. (I just figured that out after having had the belt replaced once.) The tensioner caused the tracks inside the crank pulley to deform slightly but enough so a belt with only a few hundred miles on it is all chewed up inside.

I have since researched posts on NAM and learned that Detroit Tuned sells a $20 stop cable to put on the tensioner that prevents this problem. I bought one, along with a new tensioner and just installed it.

BTW, I do have a 15% S-charger pulley already installed.

I have removed the stock crank pulley easily enough by going through the right front wheel well. It was easily accessible (DT rented me the tool for $20) But turning my attention to removing the alternator pulley, I can't see any way to remove and reinstall the alternator pulley without actually pulling the alternator itself. The service manual only addresses removing the entire alternator- and that involves removing half the front end to get it out. It's just a lot to go through to get at the blasted thing. But otherwise I'm not sure if I can even get a socket and rachet in the alternator pulley and if I could I'm not sure how I would prevent it from spinning while undoing the bolt.

Does anybody know if there any shortcuts? Any help or suggestions would be greatly appreciated!

 

i've been on the fence about purchasing an alternator pully simpley because i've heard it's a huge hassel to get to. i'd also like to know if there's an easy way to install it, i think it makes sense to get it with other pulleys installed but am not thrilled about the install

 

i think you can use stock belt with a 15% pulley and a 2% crank

 

it seems like a hassle, but it's not. Then the alternator comes off pretty easy.

Then removing the pulley? Don't know, haven't done it. But learning how to lean the whole radiator support forward give you access to the A/C, the SC the Alternator and a bunch of other stuff. If you purge the A/C and drain the radiator, you can take the whole friggin thing off and really have access to do some serious work.

But once you learn how to put it in service mode, it's about a 10 min job...

Matt

 

what's service mode/ how do you put the car in service mode?

 

It's when you take two long Phillips head screwdrivers or threaded rods and put them in the front frame rails and let the core support pull out without letting it drop down so that you can service the engine, hence "Service mode".

 

take off the bumpber cover, this is about 8-9 fasteners and some clips to lights.

Take off the al extrusions that's the real strength behind the bumper cover. Then the radiator support comes forward. I don't use the rod extensions that I should but the radiator hoses provide pretty good support.

Oh yeah, you also have to undo the 10mm bolt in the center of the upper radiator hose that's attached to the intake so things can move forward.

Then you can get to the back of the alternator to undo the electrical connectors, and the bolts that hold it onto the block.

Take the belt off first though....

Matt

 

am i wrong? alta website says you can run stock belt size with a 15% PULLEY AND A 2% CRANK. am i missing something or something i dont know?

 

the altanator pulley is to slow down the alternator (close to stock speed) due to increasing crank pulley size or running a reduced sc pulley

 

If you don't reduce the alternator pulley size there is a danger that the alternator will turn too fast, thus overcharging the battery.

As an update, I have taken the off the bumper cover, backing and radiator support and have had to now wait until I can get a friend over to help hold the radiator support assembly while I remove the alternator. I don't have the 4" metric bolts the manual recommends to slide the assembly forward and rest it; and it doesn't look like that will add much working room anyway. If I remove it I'll have to recharge the A/C, replace anti-freeze, etc. for disconnecting those hoses. I don't think that's necessary and it will be alot more work.

I'm still wondering though, once I get the alternator off, how to hold the alt pulley while undoing the nut. I guess it's no big deal if I have to clamp the old pulley since I'll be replacing it anyway. But if anybody has done it please let me know. THANKS.

Meanwhile, I'm off to our PittStop MINI Club's garage day for a couple of hours (sans MINI) just to socialize and see if anybody there has any insight. I'll let you know how it goes.

 

No need to take the AC lines loose...just take out the two 10mm bolts and let it drop down out of the way. And, I've found that an impact wrench is the way to remove the nut on the Alt pulley. I hold onto the pulley with a rag and just "zip" it off.

 

Thanks very much chadtoolio! I appreciate the tip.

 

Huh?

 

doesn't know about the regulators that are in cars. An alternator is a wonderful thing becuase it can give high or low current at lots of RPM range...

Really, a 2%-4% increase in speed for the alternator is nothing to worry about. Also, because the load from the alternator is regulated, the notion that you gain tons of power back by slowing it down (at least for a couple of %) isn't a very good one either.

You may gain a tiny bit of reduction in rotational mass by the different pulley material, and you may decrease parasitic drag a tiny bit as well.

Matt

 

Here's what service mode looks like.



To make things very easy to get to and change the coolant at the same time, drain the radiator and remove the radiator support, carfully swing the AC core out of the way and suspend; notice the alternator at the lower left.


An impact will remove the nut or one of these sockets and a 10mm to hold the shaft.

 

If a smaller pulley makes the SC spin faster, I'm pretty sure you'd need to INCREASE the alternator pulley size to slow it down.

 

Thanks K-huevo. That helps a lot. I like the way you suspended it with the bungees. In the other picture, what did you use for the hanger bolts? Were they just 4" metric bolts or the tool called out in the manual? If they were the bolts, where did you find them?

But I could do with a coolant change anyway so I might go the other route instead. BTW, did you tear your car a part and take those pix just to show me how it's done?

And no, DR. O, I don't know much about alternator's working performance, but from what I read the alternator pulley change is highly recommended to compensate when you change the crank pulley size. I'll see if I can find the related links again and post it later. What other explanation would there be for this? If you know please share it with me so I will have a better understanding. Thanks!

 

Dr O- this is one thing that made me believe the rationale for changing the alt pulley was to prevent overcharging:
http://www.mossmini.com/Shop/ViewPro...51&SortOrder=2

Here is the pertinent text from that link:
"If you have a 15% pulley on your supercharger now, you can add the ALTA Performance™ 2% overdrive crank pulley and make your 15% pulley perform like a 17% pulley. An underdrive pulley for your alternator is highly recommended if you run an overdrive crank pulley so your electrical system doesn’t over charge.

 

FWIW, I've been running the 15%+2% combo using a stock size belt for over 100K miles with no issues, including over-charging the battery.


Jim

 

If you're running the stock crank pulley, then simply changing out the supercharger pulley will have absolutely no effect on the alternator speed.

The *only* time you need to consider an oversized alternator pulley is when fitting an oversized crank pulley, and even in that case, I don't know that a few percent would matter unless you're consistently running near the top of the engine's rpm range.

 

Don't learn how systems work by reading add copy from vendor sites. It's the WORST way to learn how stuff works.

Think of it. If that were true, then if you did a long drive in a car with a charged battery, it would overcharge! There are voltage and current regulators in the charging system for a reason: So that they can provide high current when you need to recharge, and low current to no current when the battery is charged to capacity. If they weren't decoupled, we'd all be screwed changing a battery every few months, cause we'd overcharged it driving on the freeway.

Matt

 

Matt to the rescue - good post!

While it's true that you could *mechanically* overspeed the alternator and damage it, that's not going to happen simply because of a 2% oversized crank pulley.

 

MindTheGap, I used the BMW modular front end extensions 11-8-400. You asked about a method for access, I enjoy sharing regardless of whether I endorse your choice or not; in this case I think you should forego the alternator pulley and save money for something worthwhile like the Sprint Booster.

 

K-Huevo- what is a sprint booster? (Damn I feel dumb-but trying to learn)

Dr. O- Thanks for the education Matt. I wish I waited for this advice before tearing apart the front end! I've gotten this far, I think I'll just finish the job since I already bought the alt pulley.

BTW, I have read on other posts from mini2 that some people have experienced issues with the crank bolt loosening after replacing the lightened pulley. I note the manual says the bolt should be replaced if removed. Also, would never-seize cause the bolt to back-out? Should lock-tight be used? Does anybody have any thought on this?

 

Sprint booster is a gizmo that goes between the e-gas pedal and the ECU to remap the demand curve. Makes the car think you're pressing the pedal more than you are. There's a lively debate on it's merits under a thread named.... "Sprint Booster"!

Better late than never. But WTF, more parts are more fun, and learning how to do "service mode" is worth it to learn, even if it is to instal a part of dubious value.

The debate on the lightened crank pulleys have no end in site. You can flush a month of sundays down the toilet reading the pros and cons. The real killer to rotational energy in the driveline is the flywheel, as it's about 30 lbs and about a foot+ in diameter. Compared to changing that, all the rest of the little things are chump change. That siad, the crank pulley is easier to get to for sure! Many have changed them and are happy. Many haven't (like me) and are happy too!

Matt