Pulley alignment

[stevieturbo]

Anyone reccomend any tools for checking this ?

Im having some belt issues, that usually result in a shredded belt.

My crank pulley should be 100% and looks to run true. But I had to have my blower pulleys custom made, so I chose pulley dimensions.

By eye, it looks pretty good. But unless belt is extemely tight, it gets shredded after about 1st, 2nd, then 3rd gear, a lot more often than I can handle. Belt wrap isnt great, I'd guess at around 200-220 deg at best. But when very tight, belt seems to last. But it also caused me to wreck the blower bearings.
I also have slippage, despite being on a 10-rib 8.25/3.15 combo on YSi, again, unless its very tight. When tight, it works fine.
By tight, I cannot turn belt thru 90deg, and it plucks like a guitar. At 120lbft by Blownbys suggestion in the Vortech bracket, belt grips, but it feels damn tight.
At 80lbft, I get slippage above 7psi.

I tried moving tha idler closer to get more wrap. Belt shredded much easier.

Current belt is 63" long, Gates Micro-V driving the blower only. Blower is first item from the crank, with quite a long 19" of belt with no pulley contact.

I do have belt dust, but wouldnt say its excessive ???

How accurately must the pulleys be aligned ? My bracket does flex visibly when the belt is tensioned. Not a huge amount, but it is visible. I assume this too would effect alignment ?

Lots of questions...but I need this sorted. I want a system that grips all the time, without having to resort to tightening for racing, and slackening for the road. If I could get say 3000miles without even having to think about the belt, I'd be more than happy.

[stevieturbo]

Given I am now running smaller pulleys. The cogged system I used to have, could probably work again ( dictated by belt lengths available )
I'd have to buy new pulleys of course.

Is a cogged sytem a bad idea for road use ? How reliable are they when working correctly ?

[BLOWNBY]

If you have issues throwing serpentine belts i'd imagine you'd have a much worse time with Cog belts.

[BLOWNBY]

Also with my experience on the YSi it does have more drag than most blowers. i.e. more tension needed, more dust, more slip.

Still odd that you have so many issues. do you have a stock crank pulley to try and rule out you custom crank pulley?

[stevieturbo]

Ive asked Lee at ASP to get me the Gates laser alignment tool, as most likely this is where my problem lies.
Crank pulley visibly runs true. I specced the blower pulley offsets, as measured with a straight edge off the crank pulley, so more than likely thats whats wrong, although it looks fairly straight.

But most say, even a few thou off, will cause problems.

Another thing possibly....could the very long section of belt, although it is the drive side, cause issues ? Belt is 19" long with no support at longest point.

[BLOWNBY]

Another thing possibly....could the very long section of belt, although it is the drive side, cause issues ? Belt is 19" long with no support at longest point.

My longest section Crank to SC pulley is a good 18" (just measured) so that shouldn't be it!

[stevieturbo]

Cool...nice to know I can rule that out then. It must be alignment.

[speedytang]

If you bracket is flexing when you get the belt tight it is also flexing when you rev the engine because of thrust torque. You can have aligned pulley and still be skipping over because of the bracket flex.

[stevieturbo]

The bracket does flex a bit when tightening. Hard to imagine it flexing more once tight though.

When the belt doesnt shred, it does stay in place and doesnt walk. When it shreds, it literally does it within seconds of revving it 1st, 2nd and 3rd.

Thing without a strut brace, supporting the blower from flexing will be very difficult. Dont really have room for a strut though.

If someone made a custom strut brace that had the bearing and bolt within the crank pulley, so only about 3/4" sat outside the pulley ( including any nuts or bolts ), I could work with that.

I'll just check alignment first when I get teh laser tool, and see how that goes.

[BLOWNBY]

FWIW, my braket noticably flexes when tensioning and would imagine it still does upon a hard acceleration. I have never thrown a belt. Also the braket flex is normal for Vortech's. The only way to eliminate it is with some sort of brace. This is the big issue on cogs. Sepentine setups should handle this flex. Something else I'd imagine is way wrong. Unless you have some serious flex going on.

[stevieturbo]

Its just a little bit of flex...

Just had a nosey at your pics Blownby.

Your blower is actually the last item seen by crank, not the first like mine.

I think someone suggested, that on lift off, the inertia of the blower could cause the long side of my belt to go slack, which could lead to the belt jumping about.
On yours, that could only happen between blower and idler/tensioner. A very short piece of belt.

I could possibly fit a strut brace like this, if someone could make one ??



At least then I could gladly tighten it and leave it like that.

to fit this

[BLOWNBY]

Just had a nosey at your pics Blownby.

Your blower is actually the last item seen by crank, not the first like mine.

It is the first and last as it is the only thing driven on the belt.

You have other things driven by you SC belt. I take it you only have one belt. Us ford guys have a drive belt for the SC only and one for all the accesories.

[stevieturbo]

When I say first and last. The first thing your belt sees, is the idler/tensioner.

Mine is like yours, but on opposite side of engine. Crank - blower - idler - crank again

Mine is Crank, blower, idler, crank

My setup is similar again. 6 rib drives all accessories as per factory. Then alloy pulley mounted on new powerbond crank pulley drives the blower.

[BLOWNBY]

Actually since the crank rotates clock wise it goes:

Crank--> Blower --> Idler--> Crank

[stevieturbo]

?? crank to blower on yours would be the slack side of the belt.

driven side is crank, idler, blower.

In order for yours to go crank to blower, the belt would need to push......