Cleaning teeth off of cog belts... what to do?

[Andrew]

I've got a passenger side YS trim with the small 35mm pullies.

Last weekend I took the car to the track with 72/27 and 72/26 pullies.

I shift the 'glide at 6900... but I never got there.

Both passes (one with each pulley) I cleaned the teeth off of them at around 3/4 of 1st gear.

Both times I had tightened the blower belt such that I had 1/2-3/4 inch of play in the belt.

What can I do to fix this?

Thanks!

[Spence]

Andrew,
any pulley under a 30 tooth is gonna wipe the teeth right off, the belt wrap is way to sharp under 30 teeth, especially with the 35mm wide belt. Get the 77 tooth vortech crank pulley and a 28 blower, as long as you stay under 7000 you should be ok, the impeller speed will be slightly higher than what you have now, unless you can get a 29 pulley, it will be real close. Are you using the Kevlar belts? bracket flex will also do this, if the cog belt catches the edge of one of the pulleys that doesnt have a ledge it will clean the teeth right off too.

I know what your going thru, I been there.....hehe.

[Andrew]

Originally posted by Spence
Andrew,
any pulley under a 30 tooth is gonna wipe the teeth right off, the belt wrap is way to sharp under 30 teeth, especially with the 35mm wide belt. Get the 77 tooth vortech crank pulley and a 28 blower, as long as you stay under 7000 you should be ok, the impeller speed will be slightly higher than what you have now, unless you can get a 29 pulley, it will be real close. Are you using the Kevlar belts? bracket flex will also do this, if the cog belt catches the edge of one of the pulleys that doesnt have a ledge it will clean the teeth right off too.

I know what your going thru, I been there.....hehe.

Spence, thanks for the advice! I don't think that the belt is catching the edge of the teeth as I have ASP pullies which have the sides on the blower pulley... and the crank pulley is so wide that I can't see the blower belt going off the side. I have an HPM adjustable blower brace which I preloaded to keep the belt in the center of the crank pulley under load.

You're going to kill me, but I use Gates T146 belts (equivalent to a 1392 polychain)... just regular import timing belts... not powergrip or polychain or anything. I've got a hookup on them... and they have lifetime warranty! lol

Unfortunately, I put the 77 tooth crank pulley on and they won't fit... just a little too short. It looks like I'm going to need a belt a bit bigger than 56 inches. I guess a 1440 polychain will work.

What did you end up doing? Was there any solution to this besides going to a 50mm belt setup?

Thanks again!

[Spence]

even with the crank support brace it still schreaded a belt on every pass, the solution was to move the blower to the drivers side and go 50mm setup.

[Brcuda]

Originally posted by Spence
even with the crank support brace it still schreaded a belt on every pass, the solution was to move the blower to the drivers side and go 50mm setup.

If it still shreaded belts with a crank support, what are the benefits of running a crank support.

[Spence]

its was schreading cause I was spinning the living SNOT outta the blower, 71K impeller speed, and most runs I had to pedal it cause of the drag radials.......nothing can help the belt at that point when its that skinny. I ran 77/28 pulleys on both sides, the fix was the 50mm belt........

the support actually takes some stress off the crank(well I would like to think so anyway) to

[Brcuda]

Is it a good idea to run a crank support while running an 8 rib belt?

[Spence]

all the renegade guys do, if your cranking the crap outta your belt tension, you should have one.

[Andrew]

Update: I put 77/28 tooth pullies on the car along with a 1392 mm powergrip belt on the car and took it to the dyno. It cleaned the teeth off of the belt at ~6400 rpm. :( I'm going to try the same belt with a 75 tooth crank pulley.

[Spence]

hehe, yep, I was smoking a belt every pass with the 77/28, but I was getting 7500 rpms outta it. not sure what else to tell you......this is what sucks about superchargers.......

[Andrew]

Another update: I took the car out to the local 1/8 mile track with 75/28 pullies (17.2 psi after the igloo)..... I cleaned the teeth off of the belt around a second after I clicked 2nd gear. I didn't pedal the car at all, the gas was to the floor the whole way (according to the datalog).

The car went:

60': 1.3784
330': 3.8150
1/8: 5.9495
MPH: 110.97

What surprises me is that the belt shredded after I clicked 2nd (yes, it could have started wiping the teeth in 1st, I don't know). Looking at the datalog it looks like I clicked 2nd, the motor sat at stall speed (5700) for a second or two, the revs started to climb and then the boost went away. I pulled back around to my pits, took the hood off and the belt was still on the pullies, but no teeth on the inside.

Could this be a setup problem with my pullies or is it just that the teeth on the belt aren't strong enough to take the force?

I'm going to run in the renegade class at FFW Dallas next weekend and was hoping to be somewhat competitive (read: have a chance to go a round or two) but it looks like I'm going to have to put the 72/28 cogs back on and be slow. :(

[Spence]

strange........I would double check your alignement......use a straight edge across the crank pulley up across the blower and idler. something else......do you have a smog pump on the car. or something mounted between the brackets where the pump once mounted under the blower?. I didnt and this caused major flex under heavy boost. once I made a spacer to go in there it stopped alot of the belt troubles........also double check your brackets to head bolts, Mine came loose one time and same thing.......belt schreadage........just some other things I thought off.

[Andrew]

Update:

I do not have a smog pump, but I do have a spacer that I made to take up the slack (I had the good fortune of reading one of your threads on the corral discussing this issue).

I checked all of the blower bracket bolts and they were tight. I got to looking at my blower pulley (I use ASP, which has the sides on the blower pulley instead of the crank pulley) to tensioner misalignment and found a .004" misalignment between them... I was able to make this a .001" misalignment. I'm not sure if this is my problem or not, but it could contribute. I'll find out at FFW Dallas this weekend!

[Andrew]

Originally posted by Andrew
Update:

I do not have a smog pump, but I do have a spacer that I made to take up the slack (I had the good fortune of reading one of your threads on the corral discussing this issue).

I checked all of the blower bracket bolts and they were tight. I got to looking at my blower pulley (I use ASP, which has the sides on the blower pulley instead of the crank pulley) to tensioner misalignment and found a .004" misalignment between them... I was able to make this a .001" misalignment. I'm not sure if this is my problem or not, but it could contribute. I'll find out at FFW Dallas this weekend!

This seems to have been my problem. I was able to keep a belt on for a whole pass with the 75/28 pullies... in fact I got 3 passes in before the belt started to look worse for wear.

9.24 @ 147 was my best et. :)

[Spence]

kewl deal Andrew.........nice ET......congrats