I’m starting to have a nice collection of junk belts which have delaminated cogging. from the backside of belt. I’ve verified alignment and all that jazz. The phenomenon of destruction seems higher with the 29 upper pulley. I get about 100-125 runs when I run the 31 or 33 upper. The 29 upper results are all over the place.

I’ve ran various brands of belts, Mitsuboshi (what tbs sells) seems to hold up the best. I’ve ran some cheap stuff in a pinch and get a weekend sometimes.

Are there any belt manufacturers you guys are having better success with or are we just dealing the nature of the beast with a 2” width belt?

This is a little off topic but....

Did you see any gains from swapping to the 29? I have one but figured it was a waste cause the blower would be out of gas.

Did you consider running the 67 bottom? They offer it but I'm pretty sure most kits were sold with the 64 bottom. Gives you 3 teeth on the bottom and 67 + 31 is 1 tooth better than 64 and 29. Might solve your belt problems.

Maybe Apples and oranges but I ran the same Star Racer 8MM belt for 4 seasons, HH 14/71 30 plus lbs of boost. It looked perfect when I finally swapped it for a new one because I felt guilty.

The 29t is worth about a few hundredths over the 31. I only run the 29 when running q16 stuff. I’ve ran both 67 and 64 bottom. Never really in the same tuneups.

Last I checked star didn’t make 2” width 8mm belts, but it’s been a while since I last checked.

I'm going into year 4 with the same belt (knock on wood). Changing between 33, 31 and 29 for the q16 also.
How tight are you running the belt. Most overtighten the belt (on a cold engine) not allowing for block and head growth when the engine heats up. At operating temp you should be able to turn (spin) the idler pully by hand.

I don’t run the belt tight. I set it cold then fire it up and check when at operating temperature and adjust if it’s too tight. I set where I can turn the long side of the belt 90°. I’ve never attempted to turn the idler pulley though. I’ll give that a try with the new belt.

quote:

Originally posted by Big Steve:
Maybe Apples and oranges but I ran the same Star Racer 8MM belt for 4 seasons, HH 14/71 30 plus lbs of boost. It looked perfect when I finally swapped it for a new one because I felt guilty.

Star race makes some 50 mm width belts, naturally not in a useable length in my application haha

Off topic but are any of you guys running a terminator with your tbs 250? Looking to compare notes on tuneups with different pulleys as we’re early on in tuning it.

I’ve only ran a 1250.

For what’s it’s worth jones racing products has 50mm belts made from Kevlar.

Any chance you can borrow another 29 pully and see if it lives any longer. Possibility of incorrect pitch on your pully causing an early demise of your belts?

We were having an issue tearing up belts last year. We tried new pulleys, shimmed the idler so the belt was dead center, nothing helped. It would start fraying the edge of the belt and then start coming apart. This winter I pulled the bracket off that holds the idler, I laid it on a piece of flat glass and it had a rock to it, not bad but just a little. We changed that piece and it seems like it has fixed the issue. We have made about 50 passes and have not noticed any fraying.

quote:

Originally posted by JAFR:
We were having an issue tearing up belts last year. We tried new pulleys, shimmed the idler so the belt was dead center, nothing helped. It would start fraying the edge of the belt and then start coming apart. This winter I pulled the bracket off that holds the idler, I laid it on a piece of flat glass and it had a rock to it, not bad but just a little. We changed that piece and it seems like it has fixed the issue. We have made about 50 passes and have not noticed any fraying.

Interesting, I would think the machine tolerances would be better than that. Could come with load of belt also. I’ll pull it off and toss it on a surface plate.

i use jones belts

quote:

Originally posted by Triple Nickel:


Did you consider running the 67 bottom? They offer it but I'm pretty sure most kits were sold with the 64 bottom. Gives you 3 teeth on the bottom and 67 + 31 is 1 tooth better than 64 and 29. Might solve your belt problems.

That's the first thing I thought. If you're getting way better belt life with a larger top pulley just change the bottom pulley so you can run a 31-33 top pulley. Hell maybe a 34 tooth pulley the nelt will live for years??

20+ runs and the jones looks good as new