I am going to convert my 10" secondary to a 10.4 by machining the sheaves. All I could find on this forum about doing this was from Barrett as seen below.
to mod a 10" clutch, simply have .055" machined off the bottom part of each sheave, where they touch together when the clutch is fully closed. you may also have to grind a small portion of the lip off of the gold spacer shim that is directly under the helix( I had to). you then need to run a longer belt - find 1 that is 46" long, and 1.440" wide. I like the pol 1099, but cat's 046 fits too, as that is the stock belt for a m sled with a 10.4", there are a few others as well.
lastly to make it all work, you need to remove a .060" shim from behind the sec clutch(compared to the cat alignment bar), because when you get the deflection right, the belt will be hanging 3/8" over the top of the sheaves, and since the belt has a tapered side, it is effectively further to the outside compared to when it sits flush in the sheaves.....make sense?
this is an old flat lander trick for snow-drag racing, but it can be appyed to alot of applications. It works especially well on the 10" DD secondary's because they have such a small diameter at high shift ratios, and full shift ,that they have little belt side contact,and suffer ALOT of belt slip.
the cut clutch allows the use of a longer belt which stays out of the large OD ratios dsigned into the DD secondary.
overall - it efectively gears down the sled(max of aprox 10%od acheivable after mod), and gives the belt a fighting chance at survival when at high track speeds. this also shows why the DD secondary clutches respond favorably to STIFF secondary springs.
Has anyone else done this and is Barrett's info acurate? Wouldn't I want to machine .060" off of each side as the shim I am adding is .060"? I guess .005" probably doesn't make much deference. So if I machine .055" off of both sheaves where they come together down by the shaft, they will be closer together by an overall of .110", right? I am just worried about machining too much material away and loosing sheave surface on the belt when the clutch is full shifted out. For example, once you make this mod there is no going back to using a 036 belt as when the clutch is fully shifted out the belt would no longer be on the sheave surface. It would be wraped around the shaft and belt would be pinched by two veritical walls.
to mod a 10" clutch, simply have .055" machined off the bottom part of each sheave, where they touch together when the clutch is fully closed. you may also have to grind a small portion of the lip off of the gold spacer shim that is directly under the helix( I had to). you then need to run a longer belt - find 1 that is 46" long, and 1.440" wide. I like the pol 1099, but cat's 046 fits too, as that is the stock belt for a m sled with a 10.4", there are a few others as well.
lastly to make it all work, you need to remove a .060" shim from behind the sec clutch(compared to the cat alignment bar), because when you get the deflection right, the belt will be hanging 3/8" over the top of the sheaves, and since the belt has a tapered side, it is effectively further to the outside compared to when it sits flush in the sheaves.....make sense?
this is an old flat lander trick for snow-drag racing, but it can be appyed to alot of applications. It works especially well on the 10" DD secondary's because they have such a small diameter at high shift ratios, and full shift ,that they have little belt side contact,and suffer ALOT of belt slip.
the cut clutch allows the use of a longer belt which stays out of the large OD ratios dsigned into the DD secondary.
overall - it efectively gears down the sled(max of aprox 10%od acheivable after mod), and gives the belt a fighting chance at survival when at high track speeds. this also shows why the DD secondary clutches respond favorably to STIFF secondary springs.
Has anyone else done this and is Barrett's info acurate? Wouldn't I want to machine .060" off of each side as the shim I am adding is .060"? I guess .005" probably doesn't make much deference. So if I machine .055" off of both sheaves where they come together down by the shaft, they will be closer together by an overall of .110", right? I am just worried about machining too much material away and loosing sheave surface on the belt when the clutch is full shifted out. For example, once you make this mod there is no going back to using a 036 belt as when the clutch is fully shifted out the belt would no longer be on the sheave surface. It would be wraped around the shaft and belt would be pinched by two veritical walls.