Shim thightness on two dics bulley clutch

Interesting question.
.025 for me would be fine .
At . 040 im wondering why so much.
Honestly don't think i have ever seen over . 015 .
 
JPMKarting said:
I wouldnt use more then .030 worth of shims.

I prefer to use as little shims as possible, and adjust air gap via floater thickness.
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I always did the exact opposite. Thickest floater possible, take out shims as discs wear. That being said, I do not consider myself a clutch expert.
 
Chipg56 said:
I always did the exact opposite. Thickest floater possible, take out shims as discs wear. That being said, I do not consider myself a clutch expert.
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Don't need to be an expert, keeping the air gap right, spring height right, and keeping it clean is a large part of the battle imo...
 
If memory serves me right, for a bully clutch to work as it was designed to do, air gap min .035, and max is .050, if your below .035 to start, too few shims, if your above .050 too many
shims, you can use either shims or different thickness floaters, or a combination of both to get the air gap to where it needs to be...
 
Chipg56 said:
I always did the exact opposite. Thickest floater possible, take out shims as discs wear. That being said, I do not consider myself a clutch expert.
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I like to use a thick floater myself for warp, BUT....id rather use an .065 floater and 2 shims versus an .085 floater and 4 shims. The higher the stack of shims, the more likely the pressure plate and drive hub plate become unparalleled when the shims compress.
 
A thick stack of shims can certainly compress...but do they compress differently side to side if the bolts are all torqued the same?
Getting the air gap correct is more critical than if you use 2 or 4 shims in my opinion.
Personally, I don't like a lot of shims. I'd rather use a thicker floater disc. I prefer to use genuine Bully friction discs and don't mind reusing them if they are still within spec. I think they get better with wear/heat cycles/etc.

.030" is the air gap you want to aim for on a Bully in my opinion. You can run up to .045"-.050" but why would you if you have the ability to adjust it? Keep it as close to the same air gap from one week to the next to maintain consistent performance.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
www.youtube.com
35 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
CarlsonMotorsports said:
A thick stack of shims can certainly compress...but do they compress differently side to side if the bolts are all torqued the same?
Getting the air gap correct is more critical than if you use 2 or 4 shims in my opinion.
Personally, I don't like a lot of shims. I'd rather use a thicker floater disc. I prefer to use genuine Bully friction discs and don't mind reusing them if they are still within spec. I think they get better with wear/heat cycles/etc.

.030" is the air gap you want to aim for on a Bully in my opinion. You can run up to .045"-.050" but why would you if you have the ability to adjust it? Keep it as close to the same air gap from one week to the next to maintain consistent performance.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
www.youtube.com
35 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
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Unless you have some robotic tooling that tightens down all 6 bolts at the same time and the same torque, then yes.
 
JPMKarting said:
Unless you have some robotic tooling that tightens down all 6 bolts at the same time and the same torque, then yes.
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Do you torque these bolts?
My experience with cam driven fuel pumps from the big car says that the tightness and order that you tighten these bolts affects the "squish" more than anything. (Ex, the tighter you make the bolts on an old Hilborn pump, the higher the pressure it'll make simply by compressing the area.)

A real easy way to check this "squish" or compression of the shim stack on a Bully is to have a thick shim stack on a Bully and assemble the bolts as you usually do (alternating across similar to wheel lug nuts on a car.) Check your air gap to be certain that it is equal all the way around. Then tighten 3 bolts in a row just a smidge more. Now check your air gap and you'll see that the side that you tightened more will have slightly less air gap. Hint, it's not the steel plates compressing as much as those aluminum and brass shims. The less shims you use, the less to compress. The tighter you make the bolts, the tighter they compress.
 
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