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Discussion Starter · #1 ·
Finally wit thanks to @HTB I have got rid of my chirpy supercharger belt!

I got the Bando belt 7PK1310 with my CTS 187mm crank pulley and it was fine for 2 years and 10k miles. But I cleaned the engine bay and after that it started chirping on start up, and only when engine was warm. I think the cleaner used, may have done something to the belt backing!? I thought it was the main belt, so replaced that with a new Gates belt. All was well for about a week and then it returned. As I had to take the SC belt off, I think it disturbed the seating of the SC belt and stopped chirping until it 're-seated'.

I did the spray of water on the belt to test it was that and not a pulley.

Totally embarrassing, starting a meaty sounding S5 and then a chirpy chirp comes from the from like an old Transit!

So thought I would just replace the belt, but no one makes a 1310mm 7 rib belt! Except Bando and they are mainly US, so difficult to source in the UK. Then came across posts that Gates did a 'special' run of their RPM (Race, Performance, Muscle) belt in 1310mm length, but again this is US only, so was about to order one from the US. Then I came across a for sale ad on here from Dave (HTB) :) It was in Feb this year, so thought it would be sold. But he still had it, so transferred funds and he kindly sent it first class, got it the next day. :)

took the Bando belt off. I also removed the idler pulley and lightly sanded it to put honing marks back on it in case the shiny surface was causing the chirp. The OE belt has a textured backing, so probably why they don't chirp.

Without cleaning up the idler pulley, it only took about 15mins to replace the belt.

this was about 4 weeks ago and a 400 miles round trip to Norfolk for a holiday, no more chirp! :)

Fingers crossed it doesn't return!
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Discussion Starter · #3 ·
Ha ha Dave 👍

I lived with that little bird for a year! But it didn't do it in the winter as it needed to be nice and warm/hot to chirpy chirp! :)
 

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No chirpy, chirpy and cheap, cheap.

I'll get my coat...

(Probably showing my age too!)

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My I ask where you sourced the RPM belt?
 

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Discussion Starter · #7 ·
I think Aswad, Cadguy has got or going for all out 206mm pulley! So will need a 1340/1350mm belt :)

Dave - do You know how much tension is on your belt? As according to the Audizine pulley and belt Excel charts, the 1310 fits a 194 pulley!? But it does say work in progress.
When I originally fitted the Bando belt, it was a struggle, but it was because I wasn't doing it the right way and didn't have proper belt wrenches.

The RPM belt just slipped on using my fingers. It's when the the fitter tries to put it over the SC pulley last that it is very difficult, as I did on my first fit. But I guess MRC know what they are doing!
 

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@Dave Kwatro I had a team of 2 indy mechanics working on it together (with over 30 years VAG experience each) and they couldn't get it to fit at all. They had to give in!

@Dippy has the same 189 Vdamper pulley as me. Before I went Stage 2 he and I swapped quite a few DMs about 1310 v 1325 for our pulley. We'd referred to the Google Docs spreadsheet but Dave (what is it with so many Daves owning S5s, haha) did some 2πR maths to calculate that 1325 is a better size for us. I gave MRC both sizes and they used the 1325, which kind of validates what my indy found out the hard way.

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Discussion Starter · #9 ·
Yes, I understand as the 189mm pulley is 2mm bigger in diameter so the circumference will be ~6mm bigger, anyhoo, maths has never been my forte! :D But I believe you.

As I do a lot of DIY, I too find out the hard way! :D The only mod on my car that I haven't done is the remap! :)

:D didn't know Dippy was another Dave! Dave's are the best, we even have our own TV channel! :D
 

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Yeah I'm planning on 206mm and have a 7-rib 1350 gates (non RPM) which came with my pulley. Ideally I'd like an RPM but they don't make a 7-rib 1350. The closest is a 6 rib 1353 which I may try and get
 

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Discussion Starter · #11 ·
To be honest, I would probably stick with the 7 rib 1350 Gates Micro V. They are still good quality. I have seen some shredded RPM belts on other engines, so for our engines, even the Bando belt on mine gave no performance issues, just the squeak after I cleaned the engine bay with a cleaner.

I also looked at a 6 rib 1310 belt, but it's 7 rib for a reason. :)
 

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IABED sent me that same "RPM" 1310 belt with my vdamper. IIRC I gave it to MRC but Doug fitted the Gates 1325 instead. It was only later when these discussions arose that I decided to do some quite basic maths which suggested to me that 1310 was too small for a 189mm crank pulley.

There are other things to consider. We know that most US folks have the 57mm supercharger pulley even if they also have a larger crank pulley (I guess those guys focus on the attraction of the term "dual pulley" instead of just thinking about the drive ratio). That's quite small and so the risk of bely slip is higher. One wat to compensate for that is to increase belt tension by using a smaller belt to pressure the tensioner further. The other one is the CREC engine. Audi increased the belt tension for that engine (you can get the details from the SSP guide) so it is perhaps not best to use a smaller belt which you have to struggle to install.

Yes Dave, I am one too. My initials are DPE and may years ago when I was an engineer in the petrochem industry I had to sign off document changes with my initials. One of my colleagues thought that it was funny to remark that "DPE" could be pronounced as "Dippy" and the nickname stuck.
 

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Discussion Starter · #13 ·
I agree, the US guys have this hang up on saying it's dual pulley, when the max ratio can be achieved by just the crank pulley alone. May be at first big crank pulleys were not available, so they fitted smaller SC pulleys too. And as you say the tensioner was increased from 219 to 290 so about 32% increase in tensile force.

I always wondered what your name was and the where Dippy came from! :) Mine's pretty self explanatory! :D On the VW Audi forum it was Dave Avant! :D
 
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