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Discussion Starter #1
Seen this mentioned afew times now, and bear with me as my background is Turbo cars and not SC !

What bearing does this pulley have on the engine as a whole. I have spoken to GTT and they insist on changing it. West dont seem to, JCW ??? do they, BBR dont mention it, just seems alittle hit and miss as to why some and some dont.

Sorry if this has been done before, but its slightly worrying that some people do it and others deem it un-necessary :confused:
 

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eer, BBR were the first company to offer an idler pulley replacement with a Cosworth unit :rolleyes: . The JCW conversion doesn't require one because the pulley diameter is only 13.4% smaller than stock and for whatever reason, the BMW techs didn't see a problem with the standard idler pulley for this pulley size reduction. When you run a smaller pulley (15-19%) the replacement of the idler pulley is even more important; as I and BBR have been saying all along.

It is good to see that GTT tuning offers a replacement idler pulley since many many companies have neglected this, which smacks of poor development and lack of engineering intuition to be honest. Together with their very competitive pricing and sensible engineering solutions, GTT offers alot to the MINI consumer in a market clouded by people out there to make a quick buck at the expense of the customer. I still rate BBR v.v. highly though, just take your time when making a decision and visit as many tuners as possible. For the price and componentry, GTT look to take the market by storm in the coming months.

Henry
 

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Discussion Starter #3
I stand corrected on the BBR thing then, I did say bare with me :rolleyes:

I just dont see if it is that necessary why everyone doesn't change it. If it was that open to damage, and people like West and AMD etc are running 15% pulleys without it why are these not failing ???

I agree that GTT seem to offer alot for the money, especially as a package, the only niggling thing at the back of my mind is the MTH software. Working with software every day and knowing alot about programming, it seem to be the weakest link in their offering, and in a modern ECU controlled engine, probably one of the most important parts of the upgrades :confused:
 

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Discussion Starter #4
So the Tuners that dont swap this, need to then ??

Is it worth getting one seperately, even if its a new standard one, and get it fitted at the same time as they do pulley work on the car ???

Or is it necessary that the smaller pulleys, have to have an uprated idler aswell.
 

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Hi Guys heres some info (some facts some opinion ) on Mini CS idler pulleys.
If any of you have ever removed the std idler and looked at it with an engineering hat even half on ,you can see it is poor to say the least.
1) Basically it not supported anywhere!.It should be spigoted into a location in the engine block(its not ) in fact worse than than that theres a counterbore in the block but the spacerdoesnt use it, it sits on top of it !
2) there is no location spigoting into the bearing itself on either side. In essence the only thing stopping it flapping & breaking is the 'end on ' clamping force' of one puny M8 bolt.
3)The surface finish and concentricity on the outer circumference is poor which will promote premature belt wear on the back face.
4)The bearing is a bit on the small side in terms of width and diameter for the loads imposed.
There are two ways of thinking ,one says ' It'll probably be alright' the other says 'I want things to be as best they can be'
NB If belt snaps or pulley breaks you either walk home ,or drive in limp and blow the headgasket .Neither has much appeal!
Ps . Regarding mth software, its used by Hartge & BMW mini, too.
 

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Discussion Starter #6
Once again thanks Roland, informed and invaluable information.

Sounds like the basic design is flawed, and when tuning it is worth upgrading it due to the extra strains involved with the upgrades.

As for the MTH software, I didn't realise it was so widely used already !
 

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So is the belt tensioner also the idler pulley? Sorry....It is a language thingy.
Does anybody have some pics of the aftermarket belt tensioners offered like the BBR one?

Thanks,
Alex
 

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i've spent some time examining the idler and tensioner and can say that the pulleys and bearings are of high quality. they run true and use good bearings with high quality silicone seals. the fixed idller has a mount that could use improvement; this would be a simple slleeve with a shoulder to properly center and support the wheel. the tensioner assembly is also well made except that the lever arm holding the wheel is a weak cast part (that is what snapped in the pic above). there have been reports of the dampener failing, bolts loosening and the spring retainer "twist" breaking off.

No one has proerly explained jus what the "Cosworth" style tensioner is; anyone know?

I seems one failure mode can be induced by excess stress placed on the tensioner arm when releasing tension using the lever bar too when changing pulleys or belts.
 

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The tensioner pulley is not the idler pulley TBH that could be better too.I dont know of anyone that change that, I think many people confuse the two. The GTT Idler pulley is
not a modified to fit cosworth part ,it is designed from scratch for the Cooper S . In terms of the the std one running true /good finish it depends on what your'e measuring standards are .. To me a good finish is one that is better than CLA 32,and good concentricity is better than 0.001" TIR.(total indicator reading)
Spigotting into the block as you suggest only attends to one of the three positions that need it. The std bearing may be ok in quality ,but the way its held in (ie a peened over lip front &back) is not ideal. Best Regards Roland GT Tuning
 

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I'm with your Roland; those stock pulleys can be improved on.

FYI: the pulleys are identical, except that the tensioner pulley is 2.550" dia and the idler pulley is 2.750" dia. On the two spares I have (from a wrecked engine with 7,000 miles) total indicator runout is .003" for each. the surface finish could be better.

so what does "Cosworth Style" mean? what does your idler pulley look like and how much is it?
 

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jlm said:
so what does "Cosworth Style" mean? what does your idler pulley look like and how much is it?
\
Yes, please. Many people in America are very interested to actually see this part. Please let us see pics (installed too), and pricing.
 

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It consists of 3 parts (5 if you count the bearing & circlip!) and is black anodised for a stealth appearance .Another feature of it is the OD is increased for 2 reasons .
Firstly to optimise the extension of the tensioner when used with undersize s/c pulley.
and secondly to increase the 'degrees of wrap' slightly on the drive side of the pulley. This will
reduce any tendency to slip which as you know loses boost. Price will be £69+vat.
available in 2-3 weeks.
Best Regards Roland GT Tuning
 
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