Gilmer Drive Belt - Tension?

GBowman · #1 (**permalink**) 04-16-2012, 02:04 PM

1"??? WOW that seems really loose-I have the same set up on my BDR-I've only got 1100 miles on it but I adjusted to about 3/8" total movement hot. 1" seems like it would possibly allow the belt to jump the bevel on the crank pulley???

V-MAN · #2 (**permalink**) 04-20-2012, 04:09 PM

Quote:

Originally Posted by GBowman

1"??? WOW that seems really loose-I have the same set up on my BDR-I've only got 1100 miles on it but I adjusted to about 3/8" total movement hot. 1" seems like it would possibly allow the belt to jump the bevel on the crank pulley???

Gary

I set mine to 3/8 deflection, that's a general "rule of thumb" for belt tension. I asked the question originaly to see if there was a 100% answer measured by deflection or pressure (thinking maybe gilmer had specs). I believe that 1" slack the belt would probably be thrown off the pullies ... I don't think there would be anyway for it not to be. The idea is to have it tight enough to charge the battery and stay on pully system. Too tight risk destroying the bearings in alt, water pump etc and too loose then be flung off, slipping and damaging the belt not charging.

GBowman · #3 (**permalink**) 04-20-2012, 07:30 PM

I am sticking with the 3/8...saw a thread on another site where they were going with 15mm which was working well. We will see...I do think the pulleys are expanding once hot which makes the belt tighter (which goes against conventional wisdom). I think folks with this set up are used to the cold belt being the tightest and are adjusting for a hot belt and not allowing for pulley expansion.

RICK LAKE · #4 (**permalink**) 04-21-2012, 04:42 AM

V-man Like Jerry been around racing a long time. If the motor is hot we ran between 1/4" and 1/2" of deflection. The problem is wear and tear on the bearings of the water pump and Alt. As long as the belt is not jumping teeth when hot I would leave it alone. Everything tightens when the pulleys, belt, and motor bay cools off. The belt is going to walk unless you have the pulleys all trued and at the same depth on the motor. We used to drill holes in the pulleys to help remove the air trapped with the motor running. This made the motor quieter and I think helped get a better deflection of the belt running. Rick L.

rpatton3 · #5 (**permalink**) 04-25-2012, 01:37 PM

Quote:

Originally Posted by RICK LAKE

V-man Like Jerry been around racing a long time. If the motor is hot we ran between 1/4" and 1/2" of deflection. The problem is wear and tear on the bearings of the water pump and Alt. As long as the belt is not jumping teeth when hot I would leave it alone. Everything tightens when the pulleys, belt, and motor bay cools off. The belt is going to walk unless you have the pulleys all trued and at the same depth on the motor. We used to drill holes in the pulleys to help remove the air trapped with the motor running. This made the motor quieter and I think helped get a better deflection of the belt running. Rick L.

Your water pump speed is 1.3 x crankshaft speed. I found this out after looking on eBay at 1 x 1 crankshaft speed and a 1.5" belt.