OK, about 2 months ago I got an Alta v2 15% pulley installed with a JCW belt. At WOT and higher revs/gears I got some pretty bad slipping but I could drive OK as long as I shifted around 4-4.5k and stayed smooth on the throttle while I looked for a shorter belt. (It's not an easy search over here )
Anyway, while waiting for a shorter belt to arrive in the mail I found threads that got me to thinking that the problem may be my tensioner (I had no holes showing with the new belt). So I got a new tensioner and installed it today... I see 1 full hole but now my belt squeals like a stuck pig There was no squeal before and I checked to make sure that the belt lines up... the only thing I changed was the tensioner

Anyone have any advice? I've got an old std belt and a new NAPA 539 sitting around, think I should swap belts again?

Thanks,

Drill

 

I've heard the Gates/OEM JCW 1374mm squeal a bit but I've been lucky to run 2 of those belts with no squealing at all(15% SC pulley with stock tensioner and with new tensioner). Try a 535 before the 539, esp with your 17% SC pulley.

Jeremy

 

what are the symptoms of belt slipping anyways?

 

Crap, I completely forgot to mention that it's a 15% pulley

 

For me it was a lack of power/sensation of fluttering above 5500 rpm. I could hear the intake sucking for dear life above 5500 rpm if you know what I mean.

I did not do anymore WOT to redline before changing out the tensioner and belt before looking at my boost gauge -sorry.

Jeremy

 

I had a 15% pulley on stock belt for about a year. I could feel in the upper RPMs that the vehicle seemed to "loose breath" if that makes sense. I have since switched to the JCW belt. The vehicle seems to pull slightly better in the higher RPMs but i too have a squeek upon cold start that lasts until the vehicle is fully warmed up. I would describe the noise as a little birdy chirping. no too loud though. Ill probably deal with the noise unless it gets worse. next time i will get the Napa 535 belt.

 

Well for me I could tell that the belt was slipping by the "whooshing" noise that I could hear whenever it started to slip. It was a similar sound to that of a turbo kicking in, only with less power

DB's up on ramps now and I'll re-seat the belt tomorrow morning and see if that helps, if not, I'll swap it out and see...

Thx

 

NAPA 060535 is the correct size that does not slip. That size is for 15% s/c pulley and stock crank pulley size. Don't bother with that 060539, it'll slip.

 

The problem I'm running into is that the JCW belt (1374mm) that I have on now is slipping too

From what I've found, the 0535 is 1379mm so that'll most likely slip as well (although I've yet to try re-seating the JCW). I have a 0532 (1367mm) belt and will see if that fits/slips if re-seating the JCW doesn't work

Thanks

 

I know that's what the NAPA package says, but it really is the correct belt for a 15% s/c w/ 0% crank. Jan of RMW, Chad of DT and I did a comparison on my R53 during a dyno tuning session and found the NAPA 060535 was the correct belt. The tensioner gets pushed such that the plunger is in the exact same position as stock pulley with the stock belt, which yields no slipping.

 

Well, reseating the JCW (1374mm) belt didn't help. The 0532 (1367mm) was NOT gonna fit no matter what I did (lol) so I threw the 0539 (1388mm?) on and the squeal went away but the slipping is back. I'm gonna go in to MINI tomorrow and get a new JCW belt and try it (It's the closest I can find to the 0535 length on short notice).

Thanks for the help and I'll let y'all know if it works

 

The JCW belt is actually longer than the NAPA 535, not sure where you got the info it was smaller.

 

I got the length from the NAPA Parts Catalog and the website

 

The link is broken, but from the link description it looks like it was for the 535 belt.

 

The way NAPA advertises their belt sizes is wrong, even on the back of the package. You unfortunately can't compare their markings with the actual belt size, even though it's close. I suppose the part number is closest to the actual size, versus the 6pk number on the back, which is longer than it really is. I think it's stupid there isn't a standard, but welcome to automotive aftermarket [rolls eyes].

 

Yup, session expired on the link but it was the 0535 product page.

The problem I have is that aftermarket belts are a PITA to find locally so if the JCW belt doesn't work then I'll have to order the 0535 online and wait the 2+ weeks for it to show up

Thx again

 

Order a couple of them so you have spares for when you have to change it every 30k miles, to be proactive. I know people can get longer out of their belts but like fresh oil, it's cheap insurance.

 

Funny.......my local NAPA had them in stock.

Good luck

 

you're not in germany .....at least i dont think you are..

 

Yeah, German mechanics (for the most part) have this "thing" (T�ÜV) about non-std mods. I had a guy refuse to put 215/45/17 tires on my rims because they "weren't allowed" You take the bad with the good I guess That's one of the reasons why I REALLY want the JCW belt to work, lol. Then I don't have to worry about it until I get back to the States

 

Well, new JCW belt went on today. No squealing but at first it slipped at anything over 50% throttle. I took her out for a little while and as the motor/belt warmed up there was no slip until about 5.2-5.5k revs. I'll take her back out tomorrow morning to see if the slip comes back full-force when cold.
I have a NAPA 0535 on order from Alta so as soon as it comes in I'll measure them both (for gp) and put the shorter one (NAPA vs JCW ) on to see if it solves my problems.
The bright side is... I'm getting pretty good at swapping belts, lol.

 

do you have the specs on jcw belt?

 

Specs?? As in length? If so it's labeled as 1374mm long.
Let me know what else you're looking for and I'll check it out