JC
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| posted on 9/6/24 at 08:45 PM |
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Supercharger belt slip
Hi all,
The Eaton M45 Supercharger on my MGB powered Locost is driven by a dual V-Belt, rather than the normal ribbed belt.
It was running fine but when I replaced the exhaust manifold recently, I noticed that the belts were worn and cracked.
I’ve fitted 2 replacements but they are screeching and slipping, no matter which way I adjust the tension.
The supercharger was loosened when I replaced the manifold as on the MGB engine, intake and exhaust are on the same side.
The belts are driven off the crank pulley and also drive the alternator, which is used to adjust belt tension.
Any suggestions on what to do next?
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Fred W B
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| posted on 10/6/24 at 08:30 AM |
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I'm pretty sure this is why superchargers are usually driven with a ribbed belt.
You can do it quickly. You can do it cheap. You can do it right. – Pick any two.
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nick205
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| posted on 10/6/24 at 03:49 PM |
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JC
Not an answer to your problem, but any reason why you used dual V belt and not a ribbed belt?
Could you change to a ribbed belt?
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JC
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| posted on 11/6/24 at 05:15 AM |
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Hi Nick,
I didn’t build the car, but it was built as a test bed for a MGB race car. The crank and alternator just have additional standard pulleys fitted
whilst the supercharger has an additional twin v-pulley attached.
I’ll ask the guy who built it why he went that route!
Anyway, it seems that the answer was a combination of careful adjustment and a bit of talc….its now running perfectly as before - It seems there is a
pretty narrow band of tension where the belts work effectively!
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nick205
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| posted on 11/6/24 at 12:14 PM |
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JC
Thanks for explaining and glad to hear you have it sorted.
Talc and Blu-Tac are often overlooked as useful workshop items 
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bi22le
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| posted on 11/6/24 at 08:16 PM |
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quote:
Originally posted by JC
Hi Nick,
I didn’t build the car, but it was built as a test bed for a MGB race car. The crank and alternator just have additional standard pulleys fitted
whilst the supercharger has an additional twin v-pulley attached.
I’ll ask the guy who built it why he went that route!
Anyway, it seems that the answer was a combination of careful adjustment and a bit of talc….its now running perfectly as before - It seems there is a
pretty narrow band of tension where the belts work effectively!
Can I get a bit more information on this as I may be facing belt slip once I get to the rolling road.
Is talc a permanent solution?
You said about a narrow band, so if you did the belt really tight it slipped more than if it was a gnats crack looser?
I have a 5 ribbed belt but hoping for ~18PSI so its going to have to do a lot of work.
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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coyoteboy
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| posted on 11/6/24 at 10:48 PM |
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I think talc just masks the slip.
Micro-v belts would be better as per the OEM drive on most cars.
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JC
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| posted on 12/6/24 at 04:33 AM |
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Hi bi22le, I’ll put up some photos later so you can see the set up.
I think that the problem when it was too tight May have been that the tension was uneven - really tight across one run but less so on the other 2 and
perhaps the slip was as it sorted itself out.
I’m not sure whether the talc actually helped or not - it was one of the solutions employed whilst I fixed it. It may have just eased things and made
it easier, I’m not sure. It all disappeared pretty quickly though!
I also didn’t want it too tight as it runs the alternator, and I don’t want to knacker the bearings on that!
I think there is no doubt a ribbed belt would work better in most respects though.
Pics to follow later.
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bi22le
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| posted on 12/6/24 at 10:01 AM |
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quote:
Originally posted by JC
Hi bi22le, I’ll put up some photos later so you can see the set up.
I think that the problem when it was too tight May have been that the tension was uneven - really tight across one run but less so on the other 2 and
perhaps the slip was as it sorted itself out.
I’m not sure whether the talc actually helped or not - it was one of the solutions employed whilst I fixed it. It may have just eased things and made
it easier, I’m not sure. It all disappeared pretty quickly though!
I also didn’t want it too tight as it runs the alternator, and I don’t want to knacker the bearings on that!
I think there is no doubt a ribbed belt would work better in most respects though.
Pics to follow later.
Thanks, ill take a look.
I haven't tried it yet but you can get belt dressing spray and belt slip sprays which may just be enough for you. If it stops working its quite
cheap so just give it a spray before using the car every now and then.
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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coyoteboy
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| posted on 13/6/24 at 01:05 PM |
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quote:
Originally posted by JC
I think that the problem when it was too tight May have been that the tension was uneven - really tight across one run but less so on the other 2 and
perhaps the slip was as it sorted itself out.
This physically isn't possible in the sense you are thinking. Assuming none of the pulleys are one-way, or stuck, the tesion in one part is
exactly the same as the tension in the others, statically. With toothed belts, like timing belts this can be possible if for example two items are
locked and the tension increased between them, but in any situation where all pulleys are "free" rotating and especially un-toothed (even if
stiff) the tension will even out. Once it starts moving, dynamically the tension may be different in different spans, but you can't set each span
individually - they'll always be some scaled version of the statically set tension.
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