Older Horstman clutch issues?

FlatheadsForever87

FlatheadsForever87

Member
Last summer I got an older horstman off a fellow racer for my mini bike. When I installed it and tried running it would not engage, I revved it up pretty high way higher than my max torque with out any results. Can anyone tell me what I can do to make it work please? I can send pics in a few if you all think it will help. Thanks in advance fellas.
 
Do the levers have weights/bolts in them? A highly modified engine does not need the weights. If you’re only turning 6500 or so RPM, you need the weights. After that, spring height adjustment will affect engagement. Back the off for a lower engagement.
 
Or pull a shim if it's got a air gap over .055 .
The disc's need to measure .115 not less then I'm thinking .112
Bully floaters will work .
 
It could simply be flat worn out.
No friction material left, big air gap, springs bound, adjusted way out of whack. Who knows.
We would need to know peak torque of your engine or at least something about the build to determine that. Then the weights on the clutch and the spring wire diameter and installed heights and go from there.
If it's been slipping at all, it's likely gotten hot and warped the pressure plate and backing plate -- very common with thinner H'man clutches.
You would do well to send your clutch off to someone who works on clutches to get it reground and freshened up. (I happen to know a guy.) :)


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
32 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
Thanks for all the answers. I'm gonna take a few photos. Brian to answer one of you questions. It's not slipping at least not yet because it isnt engaging whatsoever. As for the engine it's on is my built up 3hp. Not anything tremendous just basic blueprinting and matched up, stiffer springs, deck and head cut, valves lightened and polished, s/a moon power carb reworked a little more on the fuel signal. Geared 12/60, jetted for gas/ methanol. I'm not sure of the air gaps and spring heights as I am extremely green on this type of clutch. I may not be revving it enough to get it to lock it possibly. Idk. I'll tale some pics is a few mins after I get home from work.
 
Skidude said:
Do the levers have weights/bolts in them? A highly modified engine does not need the weights. If you’re only turning 6500 or so RPM, you need the weights. After that, spring height adjustment will affect engagement. Back the off for a lower engagement.
Click to expand...
Yes they do have bolts on them. What does this do for them exactly? Excuse the dumb questions I feel like a kindergartner lol
 
CarlsonMotorsports said:
It could simply be flat worn out.
No friction material left, big air gap, springs bound, adjusted way out of whack. Who knows.
We would need to know peak torque of your engine or at least something about the build to determine that. Then the weights on the clutch and the spring wire diameter and installed heights and go from there.
If it's been slipping at all, it's likely gotten hot and warped the pressure plate and backing plate -- very common with thinner H'man clutches.
You would do well to send your clutch off to someone who works on clutches to get it reground and freshened up. (I happen to know a guy.) :)


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
32 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
Click to expand...
Would this clutch being as old as it is be worth sending in for rebuild? I also have a older but nice looking vortex I think all I'm missing is the bell and driver from it
 
Screenshot_20211229-005812_Chrome.jpg
 
You have a Horstman 400S or possible M. With no bolts or washers in the weight levers, you're engagement is going to be very high (too high for your engine application.)
Black springs @ .285" -- put 4 machine washers with an allen bolt and nylock nut in each hole (2 per lever) and you should get this clutch to engage on your engine around 3000 rpm. We have the "official" Horstman weight bolt kits in stock if you need, or just stop by your local hardware. Make sure to get bolts that are just long enough to fit the washers and engage the nylock - otherwise they'll hit the springs and retainers.
FWIW, you can upgrade that clutch to the current style 8 tab discs and 8 tab baskets so you can just swap out drivers rather than the whole drum/driver if you choose to do so in the future.
 
FlatheadsForever87 said:
Yes they do have bolts on them. What does this do for them exactly? Excuse the dumb questions I feel like a kindergartner lol
Click to expand...
The bolts add weight to the levers and give the levers more power against the springs. The springs hold the clutch disengaged. As the clutch spins, centrifugal force causes the levers to rotate outward, compressing the springs and engaging the clutch discs against the pressure plate. Now it’s a battle between the springs and the levers. The more weight added to the levers the lower RPM required to overcome the spring pressure. If you have two holes in the levers you can use two bolts. Make sure to use lock nuts. You don’t want one of those nuts coming off while the engine is running.
 
To fine tune how each lever pushes on disk:

Put the clutch on a 3/4" shaft in a vice so it sits with the levers up.
You then can pull on a lever with a spring scale with "x" amount of force. Just pick something that is easy to feel/tell.
You then put a feeler gage inbetween the disks somewhere and "feel" how tight how ever you pull on the spring scale is on what ever feeler gauge works for you.
Go around the clutch to tweek each spring so they all feel the same.
 
Thanks for all the info fellas. I now feel a ton more confident going into this trial and error. Next is gonna be the vortex clutch I have also. Does anyone here have a used basket they would part with? I think I have a 10 tooth driver to fit one just cant seem to find the basket. Thanks again.
CarlsonMotorsports said:
You have a Horstman 400S or possible M. With no bolts or washers in the weight levers, you're engagement is going to be very high (too high for your engine application.)
Black springs @ .285" -- put 4 machine washers with an allen bolt and nylock nut in each hole (2 per lever) and you should get this clutch to engage on your engine around 3000 rpm. We have the "official" Horstman weight bolt kits in stock if you need, or just stop by your local hardware. Make sure to get bolts that are just long enough to fit the washers and engage the nylock - otherwise they'll hit the springs and retainers.
FWIW, you can upgrade that clutch to the current style 8 tab discs and 8 tab baskets so you can just swap out drivers rather than the whole drum/driver if you choose to do so in the future.
Click to expand...
Is it possible to get this type of clutch to feather into fully engaged? I'm hoping it won't be like 3000 rpm slam into lock up. If that's the case I will be on my back because I cant ride a wheely to save my life. lol
 
To create a softer engagement, tighten the air gap, and alternate weights on every other lever.
The Vortex will come in smoother (more gradually) by design.
 
WOW!!! Thanks guys I'm sure I am no where near tuned correctly but so far I have springs set at .380 thou hight, moved the bolts to the top holes and added another nut to them. It revs kinda high but it isnt throwing me off the back off the bike. Really brings this 3 horse to life for sure. All I can say is WOW!!!
 
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