Performance of a factory Bully vs rebuilt

Burris Racer

Burris Racer

Member
Is the performance of a rebuilt Bully (from a reputable builder) better, worse, or the same as a factory built clutch? The value of a used clutch + the rebuild is nearly the same as the cost of a new clutch. I go back and forth if one is better than the other.
 
Understand, this is my opinion.

If you take a new Bully and a rebuilt one, adjust them so they both hold the same engine at the same RPM with a stall test, I'm pretty sure they will have the same amount of torque at the axle. The only difference would be the amount of heat generated by the one. If the rebuilt produces more, or less, heat than the new one, it's going to transfer less, or more, torque to the rear axle. I'm pretty sure you could check the amount of heat their producing with a infrared heat gun. It would be an interesting test. Of course you'd want to keep an eye on the air density between tests.

Another test would be if they both reached the same RPM at the end of the straight. If the factory Bully showed less RPM that's probably an indication it's not working as well as the rebuilt one. Meaning it's slipping at high RPM.
 
Both a factory new Bully and a used one rebuilt properly are going to work well.

If you can find a used Bully that is pretty worn out and cheap (like $50-$100), and then spend another $100-$125 to have it rebuilt, thats always a good option. New Bully's are roughly $300+
 
flattop1 said:
If you don't currently have one go with new .
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I have three that are ready for rebuild. I'm trying to decide if I should sell these as is or send out for a rebuild. I usually sell my used clutches for $125-$150 and pay around$125 for a rebuild. The value of the rebuilt clutch is about $250 or for $265 I can by a new one.
 
JPMKarting said:
Both a factory new Bully and a used one rebuilt properly are going to work well.

If you can find a used Bully that is pretty worn out and cheap (like $50-$100), and then spend another $100-$125 to have it rebuilt, thats always a good option. New Bully's are roughly $300+
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If i was going to buy a bully for 125.00 used then 125ish for a rebuild thats 250ish and for 25.00 more i can buy brand new its a no brainer... Im buying new.
 
With the rebuild your not dealing with buying/selling issues .
That alone is a plus .
The rebuilt will have been through heat cycles and could be more consistent .
 
Bandmn said:
If i was going to buy a bully for 125.00 used then 125ish for a rebuild thats 250ish and for 25.00 more i can buy brand new its a no brainer... Im buying new.
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Notice how I said 50-100 for a used one.

We sell used Bullys with fresh rebuilds and new baskets for $225 shipped with a driver...nice alternative for those who don’t want to spend the full boat on a new one .
 
Yea, I'd agree with JP.
If you can buy a used Bully for under $100 - buy it.
I buy them for $100 shipped all day, any day, as long as they are genuine Bully clutches, don't have any cracks in the keyway, have some meat left on the backing plate for regrinds, and are complete.

We sell them for $200 fresh, set up for your class and comes with your choice of driver.

Clutch rebuilds are $50 +parts.

Now, don't think that every rebuild needs new discs. I hear of guys saying that they spent upwards of $150 for their clutch to be rebuilt previously. If we can reuse your discs (ie they are still within spec) we will use them and save you the money if you wish. I've seen rebuilds leave our shop that were $150 and others that were $55 total. We do the same machining and assembly to all rebuilds. The price depends on what parts need replaced.
With that said, I know some guys who are replacing springs on every rebuild, others who replace bearings, hardware, etc. You can, if you want, but most prefer to only spend what is absolutely necessary.
For the most part, all of the clutch rebuilders are on the same page price-wise on labor $50 is the going rate.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
31 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
Addressing performance...
Buller does a very nice job at machining and assembling (setting up) new clutches.
With that in mind, consider that clutches get warm and heat is their biggest enemy. Heat can (and will) distort the steel plates. As this happens, you will find that the pressure plate and backing plate will warp slightly. This is when a regrind is necessary. The more these plates warp, the less contact patch they offer, so they slip more, which results in even more heat, furthering the warping.
I tell people who buy new clutches from us (any brand) to run them for a few races and keep an eye on how consistent they engage. When they become inconsistent, it's time for a rebuild/regrind.
 
flattop1 said:
The rebuilt will have been through heat cycles and could be more consistent .
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JP or Brian - can you share your findings or opinions on work hardened components vs new?

As noted in my original post, I'm back and forth on which one I'd prefer given a choice and cost not being a factor. Up until recently I would choose a rebuild over new. At some point I read about this subject and my takeaway was a rebuild gave better performance / longevity. The above mentioned reason was stated as part of the justification. The article was probably written by a rebuilder ;). A fellow racer shared his methodology with clutches to be factory built for the important races, rebuilds for weekly events, and then sell when it's time for another rebuild.
 
Burris Racer said:
JP or Brian - can you share your findings or opinions on work hardened components vs new?

As noted in my original post, I'm back and forth on which one I'd prefer given a choice and cost not being a factor. Up until recently I would choose a rebuild over new. At some point I read about this subject and my takeaway was a rebuild gave better performance / longevity. The above mentioned reason was stated as part of the justification. The article was probably written by a rebuilder ;). A fellow racer shared his methodology with clutches to be factory built for the important races, rebuilds for weekly events, and then sell when it's time for another rebuild.
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I'm not a metallurgist, so take this with a grain of salt. But I have not found any difference in performance or longevity from a brand new unit to a rebuilt one.

In my experience, the Bully clutches have such a long life span, that pretty much the only time they are "junk" is when the drive hub cracks. Of course, you can replace the drive hub, heck you can replace any part. It's just a matter of how much it needs + labor rate, does it become cost effective.

Even after years of rebuilding and the plates getting thinner from machining, they still outperform and outlast most clutches. I like to use the older, thinner ones for junior classes or predator, because they dont seem to abuse the clutch as much, but would have no problem bolting them on a stocker.

I have customer clutches that are some of the very first model Bully, and they still rebuild and perform well. If cost is no option, heck, new is never a bad thing. I do however advise people to stay away from the roller lever clutches. Personally, I'm not really a fan of them, plus its an extra $90 or so that is unnecessary IMO.
 
Burris Racer said:
JP or Brian - can you share your findings or opinions on work hardened components vs new?

As noted in my original post, I'm back and forth on which one I'd prefer given a choice and cost not being a factor. Up until recently I would choose a rebuild over new. At some point I read about this subject and my takeaway was a rebuild gave better performance / longevity. The above mentioned reason was stated as part of the justification. The article was probably written by a rebuilder ;). A fellow racer shared his methodology with clutches to be factory built for the important races, rebuilds for weekly events, and then sell when it's time for another rebuild.
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Age doesn't factor into the hardening of components without any other factors. Heat will affect the rockwell hardness. I have clutches I rebuild all the time, from the early 1990's that perform flawlessly. I have brand new clutches that have been over heated, changing the rockwell, that require at the very least for material to be cut away before proceeding. The thickness of the steel is a big factor, which is why I don't like the thin .065 floater plate that has been used in the Bully for so many years. A thicker plate will reduce the chance of warpage and be more consistently reused. I try to use a .085 floater in every bully or horstman I rebuild if at all possible.
The methodology of rebuilds not being as good, better have new for a big race, etc is generally driven by someone wanting to sell you a new clutch. Can the rebuilds be better than new ? Yes. Can they be worse ? Yes. That will depend on the quality of the new clutch and the quality of the rebuild. Quality runs very deep for us, we replace everything. Springs, discs, nuts, bolts, snap ring, etc. A 2 disc rebuild is flat rate priced at $100 which includes shipping as well. You can see what is included under our Clutch Rebuild link on our website www.gofasthp.com
As Brian said, we also sell rebuilt Bully Clutches for a couple hundred bucks. It's hard to find them a lot of times, so those are few and far between depending on the time of year. Paying $175 for a used up one then having it rebuilt just isn't a good decision financially.

-Shannon
 
Burris Racer said:
JP or Brian - can you share your findings or opinions on work hardened components vs new?

As noted in my original post, I'm back and forth on which one I'd prefer given a choice and cost not being a factor. Up until recently I would choose a rebuild over new. At some point I read about this subject and my takeaway was a rebuild gave better performance / longevity. The above mentioned reason was stated as part of the justification. The article was probably written by a rebuilder ;). A fellow racer shared his methodology with clutches to be factory built for the important races, rebuilds for weekly events, and then sell when it's time for another rebuild.
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Any time metal is heated, it is stressed. The more heat, the more stress.
Hardness and finish aside, the steel plates in your clutch will move/change and take a set after a while. Very similar to a brand new engine. We used to spend a full day breaking-in new flathead engines before performing any machining to them. The cylinder moved, the seats moved, the valve guides and lifter bores moved, everything in those blocks moved. That was our primary motivation for heat cycling (breaking-in) before doing any precise machinework to them. The same can be said for the L206 and clone cylinder heads, specifically their seats. Heat affects everything, and your clutch is no different. Bully clutches are spot on when they are new, but that heat affects them just like any other brand. After a couple of race days, they ought to be looked at. Does it need re-machined? Possibly, possibly not. My recommendation has always been to have it professionally gone through when the engagement becomes inconsistent or not up to your expectations. Even if you have a big race coming up, I'd prefer to be on a clutch that had enough run time on it to bed the friction material.
 
I cant vouch for a new clutch because i have never had one, lol. However I can vouch for a rebuilt bully they are great clutches. Toward the end of last year I purchased a rebuilt clutch from Carlsons. He set it up just as I asked, and that clutch performs flawless. It will pull with or out pull some of the best in the business! My brother also had his bully rebuilt, it was done by Shannon Halbert. He ran that clutch all season without any problems whatsoever 20+ races it performed great as well. Bottom line have it rebuilt by any of the top clutch guys and you will be satisfied.
 
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