Belt Length-Pulley Question-New Owner

[03 MG VERT]

New Terminator owner here, a 2003 Mineral Grey convertible, 47k miles. This site has been my go-to, prior to and since my purchase, for learning about these cars. Had a few Fox cars over the years (all N/A) but this is a different animal! I've done many searches and reviewed reference guides (Cobra Bob's, Billetflow, etc.) trying to determine belt length for my setup. While I didn't find my exact combo, I think I'm in the ballpark, but wanted to toss this out to make sure I'm not missing something since I'm still learning here.

My car has a RR 2.75 upper, 4 pc. Billetflow pulley set (3-100mm, 1-92mm, newer style bracket), and a 2 lb Metco lower. I came up with a 77" belt...?

The belt on the car now looks to be slipping and I can't see any markings indicating manufacturer, size or part #. There's no squeaks, squealing or odd noise, but when the car gets into boost, I can smell burnt rubber and have a good amount of belt dust flung up on the underside of the hood and built up on the tensioner bracket. The tensioner is sitting close to the stop on the left too.

I've already ordered a new stock tensioner (not sure one on car has ever been replaced) and want to pick up a new belt (from what I've read prob a Gates with the RR non-slip would be best) and start there. This isn't my DD, so I'm resisting the urge to drive it until I get the belt issue squared away. There's also noticibly more wear on the back (smooth) side of the belt on the motor side. The Billetflow's also have some pretty good wear grooves in them. Once I figure out how to post pics, I'll add some for reference.

Sorry for the long newbie post! Any guidance on belt will be appreciated.

 

[Bdubbs]

Trying to figure out the correct belt sizes can be frustrating at times. I'm in the process of dialing mine in a little better as well. I have 3-4 belts in my garage lol, and I'm about to order another one. Sometimes it's best to find a auto store that will let you try a couple belts and then return the ones that are not needed.

I can't seem to find any belt dust showing my belt is slipping, however during my dyno tune last spring I had some belt slip on the dyno sheet around 6200 rpms. Many people have told me I shouldn't have any belt slip with a 3" upper but I did and the notch indicator that's on the belt tensioner was spot on to where it's suppose to be. So I'm going about a 1/2" shorter.

If I had the belt size your looking for, I'd be happy to ship it to you as I have no need for it.

 

[03 MG VERT]

Hopefully a pic of my car will attached to this!

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[FromGTtoSVT]

Use this as your guide

http://www.stangshiftergaskets.com/belt_length_chart.htm

Make sure you spin all the idlers to see how they feel, bearings in them can fail

Took me a long ass time to find the right belt, I eventually determined mine was too tight and squealed. Good luck!

 

[03 MG VERT]

Thanks for the offer Bdubbs! Yeah, it looks like belts really seem to be just a matter of trial and error. I just wanted to see if someone has a similar combo and knows a 74.5" is what works for their car, they could chime in and suggest I check my math again if I am way off on the 77"!!

 

[03 MG VERT]

Use this as your guide

http://www.stangshiftergaskets.com/belt_length_chart.htm

Make sure you spin all the idlers to see how they feel, bearings in them can fail

Took me a long ass time to find the right belt, I eventually determined mine was too tight and squealed. Good luck!

On the chart with a 2# lower, a 2.8 and 2.7 pulley are both listed at 75.5 (I have a 2.75).

If I add 1" for the aux idler, then add another 1" total (.5" ea. for the two other 100mm pullies) I get 77.5".

Is that the correct way to use the guide, or is it just add .5" if any of your pullies are changed to 100mm from 90mm?

 

[03 MG VERT]

Looks like pic worked. Here's some additional ones of the belt wear, pullies and where my tensioner indicator is at. When I pull the belt off, I'll be checking and cleaning each pulley. Prev owner said he had all Billetflow bearings replaced about 3500 miles ago.

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Tensioner:

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Belt wear:

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[Bdubbs]

Looks like pic worked. Here's some additional ones of the belt wear, pullies and where my tensioner indicator is at. When I pull the belt off, I'll be checking and cleaning each pulley. Prev owner said he had all Billetflow bearings replaced about 3500 miles ago.

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Tensioner:

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Belt wear:

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Looking at the picture, your belt is way to big! Your notch indicator on the tensioner is towards the passengers side. You see those two stepped notches to the right? That should be an idea where your notch indicator should be! Farther to the right of that (towards drivers side) means the belt is tighter, and this is why many terminator owners notch the tab on the drivers side. Right now mine is pretty tight a quite a bit to the right of those two stepped notches.

 

[03 MG VERT]

Looking at the picture, your belt is way to big! Your notch indicator on the tensioner is towards the passengers side. You see those two stepped notches to the right? That should be an idea where your notch indicator should be! Farther to the right of that (towards drivers side) means the belt is tighter, and this is why many terminator owners notch the tab on the drivers side. Right now mine is pretty tight a quite a bit to the right of those two stepped notches.

Thanks Bdubbs, that's what I thought. The tensioner is bouncing a bit too at idle. Figured I'd just replace it, this way I know when it was done, can rule it out and at $44, it's not draining the wallet.

I've read pros and cons to notching the tensioner. Pro: can run tighter (shorter) belt to reduce/eliminate slip. Con: added stress on supercharger snout and possibly crank?

Now as far as belt brands so, I see most prefer Gates and/or Gatorback. I read that the non-slip style supercharger pulley wouldn't mesh well with the cross-rib design of the Gatorback. Does that still hold true?

 

[Bdubbs]

I'm not familiar with those pulleys. I've always notched my tensioner. I too am always worried about tighter belts causing stress on the blower snout. You could probably go at least 1" shorter.

 

[03 MG VERT]

I'm not familiar with those pulleys. I've always notched my tensioner. I too am always worried about tighter belts causing stress on the blower snout. You could probably go at least 1" shorter.

Thanks again for the advice Bdubbs.

 

[Bdubbs]

Thanks again for the advice Bdubbs.

You bet, your car looks great too btw! The more I see MG the more I like it!

 

[03 MG VERT]

Wanted to update this since it can be disappointing when searching for something, finding a relevant thread, then not seeing any end result or outcome. Since I came up craps on a search for a 2.75 upper, 2# lower with a 4 pc. Billetflow set-up, maybe this could help someone down the road.

I tried a Gates K080760, 76 1/2" belt and even after notching my tensioner, found it was too small. I exchanged that belt for a K080776, 78 1/8" belt, and after putting that on, had my tensioner land right on the raised pad in the middle of my tensioner. I didn't have to wrestle the belt on, but I did remove my aux idler to help with the install. All the pulley bearings were good and spun freely. I did pull them to clean them up.

Also once I removed the belt that was on the car, I found the part number that showed it was an 80 1/8" belt. Guess that would explain the slippage...Only had time for a quick test drive after the new belt was on, but so far, so good.