Horstmen 2disc vs. wet clutch

[Tom Petalino]

What performance dissatvantages do you think the wet clutch has over running a dry clutch on a kt100. With all being equal, are we talking a tenth, half second or more? Just lap times, not considering ease of maintenance or longevity. Senior pipe class sprint racing.

[josh martin]

Tom,

In our experience, the only reasonable clutch to use for sprint racing on a kt100 is a patriot 3 disc. If your class weight is over 300 lbs, the two disc wont live. The wet clutches are great for road racing, but has far too much drag for a sprint track. After destroying $2000 worth of two disc clutches last year, then getting 6+ events out of the three disc clutches before friction disc replacement, I’d have to say the patriot three disc is the way to go.

Josh Martin

[Jay Sinon]

Josh,

I don’t know I have been running a Horstman HDC5B 2 disk dry clutch for 3 years and have never had a failure! I take it apart every couple of races Maybe change a disk or a steal to get it back into specs and have no problems. I cant imagine spending $ 2000. in clutches. What’s your stall speed does your clutch come unlocked a lot? I set mine at 8600 rpm and it only disengages in 1 of 16 turns according to my Mychron 4.

Love the Horstman 2 disk dry clutch!

TaG Sr.

[josh martin]

Jay,

To be clear, the $2000 was spent on clutches for two different karts, not that that makes it much better. There were two issues going on:
1) The engine builder was supplying inaccurate dyno curves causing us to set the stall speeds way too high, and
2) Our home track is short (4/10ths) and very technical, so you are constantly in and out of the clutch, resulting in abnormally fast wear. There was no viable solution to this other than the 3-disc, which has been bullet-proof comparitively.

Thinking logically, I’m sure if the track was a bit more wide open with fewer drastic rpm changes that the two disc would be fine. Still wouldn’t run the wet clutches in sprint racing. They do have a lot more parasitic drag.

Josh Martin

[Gary Lawson]

Wet clutches are heavier and don’t let the engines rev as easily. Just changing the clutch will increase your engine rpm which is an increase in mph.

The new style pipe doesn’t need slipped above 8600. Even 8400 would be enough and every little bit less you have it you will keep the heat down and last a lot longer. A 3 disc is unenecessary unless you are excessively heavy but their is no harm using one. The tomar is also great

[Tom Petalino]

gary, thanks for the post.  so, my origanal questions is how much slower,would a wet clutch be per lap. I race at pit race with lap times in the 1;02;00s. Im new to karting and this whole dry clutch setup thing is a bit overwhelming. i know its slower ,but im looking for low maintenance at this piont . focusing on setup and driving.

[Gary Lawson]

I would guess it’s worth between 2-5 tenths at Pitt. If you want to have lower maintenance but some of the performance advantage just slip it a little lower. 8200 would last a long time. Just need to remember to lube the bushing with tri flow every session along with the chain. Another thing to be aware of is don’t start your engine until youre about to pull onto the track. Also, don’t abuse your clutch on the pace lap before the start. The majority of clutches get far more abuse in these instances than the do throughout a whole race.

[Jay Sinon]

Gary,

Your absolutely right! I see more people do more damage to there clutch before the first lap has been completed then during the course of the race. I know the Yamaha doesn’t like to stay running on the grid or at slow speeds but I have found that if you run the low speed jet 1/2 to 3/4 of a turn it will idle without burning up your clutch then just before you start racing open the low speed screw to your race setting and let her rip.

Josh,

Thanks for the update that makes a lot more sense. We run 7/10ths of a mile with only one really slow turn and of course if you run twice the karts twice the fun twice the money!

TaG Sr.

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