Replacement fanbelt not 'flat'

[fallingoffalot]

I got round to replacing my puny fanbelt for one that looks more up to the job. I ordered a couple ages ago. One is a 907 and is slightly too big, the other is a 900 and is ok but it's twisted, well not actually twisted, but won't lie flat.

Put it on anyway and it made a weird noise, (I tried to take a vid, it didn't come out very well but hopefully gives you the jist https://youtube.com/shorts/XP6lUFdabS0)

I put the old one back on as I wasn't comfortable with the noise.

So would the kinked belt cause premature wear or would it just flatten itself out in a few miles?

(I also did a oil change whilst I was there!)

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[Coda]

It sounds very weird and I don't think I could trust it. Extra noise means extra vibration and extra heat and that usually means extra wear and premature failure. Even if the belt doesn't fail, what's it doing to the alternator bearings?

 

[ozziedog]

As said above ^^^ all the reasons for not using it. At the very least, you now have the size and maybe they’ll take it back or just order another and get that on. When you’ve changed your belt to the new one, roll your old one into three circles like you’re folding a pop up tent and but it in a sandwich bag along with a piece of paper with the size of the replacement on it, then pop it in the gap behind the passenger seat as a ‘just in case’ to get you home then you’ll never have to worry about the belt breaking and getting stuck somewhere. I’m a proper saddo as I got an old spare behind the passenger seat and another in my toolbox and I’ve not had a belt break ever on any motor :roll: I should now probably say “Touch Wood” or get a rabbits foot :shock:

Ozziedog,,,,,,,, old (very old) school belt and bracers :mrgreen:

 

[gvee]

The "twist" isn't a problem. It's just from how it has been packaged/stored and it will not affect use.

Very hard to tell from your video, but to me it looks like the belt is too slack. Either too long, or incorrectly shimmed.

 

[Coda]

then pop it in the gap behind the passenger seat

Along with a clutch cable, accelerator cable, and a full workshop's worth of tools :lol:

 

[sparkywig]

The "twist" isn't a problem. It's just from how it has been packaged/stored and it will not affect use.

Very hard to tell from your video, but to me it looks like the belt is too slack. Either too long, or incorrectly shimmed.

I agree with George, it looks like the belt is too slack. Take some shims out or use a slightly shorter belt.

 

[fallingoffalot]

Ok thanks I may give it another go then. Or at least order another. It seemed fairly tight to me with the 10mm or so of deflection. I think the twist made it seem tighter than it was. Shame I can't browse them in a shop and pick a nice flat one.

I saw an article somewhere saying that it can wear the alt bearings if it's too tight, I guess it's gotta be just right.

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[fallingoffalot]

I've just ordered an Optibelt from JK, it says it's 912mm - looked everywhere but can't definitely confirm this is outside length, hope it is! The one that is too big seems to be 907/925 (inside/outside length)

 

[fallingoffalot]

OK, put the belt on (ages ago) and it appears too loose, and I've taken all the shims out. So I ordered a 905 belt from JK but it's 9.5mm instead of 11.5. Does this matter?

 

[sparkywig]

Yes, it will sit too far down in the V between the pulley halves.

 

[gvee]

To add to that: if it sits too far down then you'd effectively need a shorter belt.

 

[fallingoffalot]

Damn it, anyone know where I could get a shorter 11.3mm belt, doesn't look like Optibelt do one?

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[fallingoffalot]

Done a few hundred miles on the 11.3mm Optibelt, it got quite loose, I've just removed the last shim from the pully and it's actually much tighter and doesn't look too bad now, so all good hopefully

 

[Moseley]

Something that might be worth considering based on my recent experience is the quality of the pulleys you’re using. Mine was a cheapo alternator pulley and an Empi aluminium crank pulley. The belt would always run quite slack, so I’d either be on one shim for a new belt, and zero as it broke in - didn’t give much wiggle room for any future stretching.

I then noticed that the top pulley was starting to deform under the tension of the belt, to the point where it started to foul the alternator. Fortunately I caught it early before it failed completely, and have now swapped to a billet CSP pulley set, and am running around 7 shims between the pulley halves - I’m much more comfortable with that.

It might be your pulleys causing your slack belt issue, rather than the belt itself.


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[fallingoffalot]

Great thanks, I'll monitor the situation closely on way to Cornwall next weekend. Then do the replacement anyway when I get back. I doubt I'll get time to do it before then.

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[sunnyside]

Great thanks, I'll monitor the situation closely on way to Cornwall next weekend. Then do the replacement anyway when I get back. I doubt I'll get time to do it before then.

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Hi, i’m going down to cornwall next weekend in my bay so may see you on the A30 . Where in Cornwall are you going?

 

[fallingoffalot]

Hi, i’m going down to cornwall next weekend in my bay so may see you on the A30 . Where in Cornwall are you going?

We're going down on Sunday, to Porthcothan Bay, Nr Padstow.

 

[sunnyside]

Hi, i’m going down to cornwall next weekend in my bay so may see you on the A30 . Where in Cornwall are you going?

We're going down on Sunday, to Porthcothan Bay, Nr Padstow.

Small world. We will be staying at Carnevas campsite at porthcothan Bay but going down on Saturday. I’ll probably see you down there then. I’ve got a yellow early bay, give us a wave if you see us.

 

[fallingoffalot]

Hi, i’m going down to cornwall next weekend in my bay so may see you on the A30 . Where in Cornwall are you going?

We're going down on Sunday, to Porthcothan Bay, Nr Padstow.

Small world. We will be staying at Carnevas campsite at porthcothan Bay but going down on Saturday. I’ll probably see you down there then. I’ve got a yellow early bay, give us a wave if you see us.

Ha, what a coincidence, we are staying at McDonalds Farm, on the other side of the bay. I'll look out for you!!