Track Tac

When to replace Noram shoes?

B

bw_bad

New member
I am beginning to suspect that my son's clutch may not be set properly or needs the shoes replaced. He is currently running the 4-cycle Junior Sportsman class on a tight sprint course. He is using the Black plate with a new LO206. His weight is 267lbs.

What should the clearance be between the drum and the shoes? What setting and spring would you suggest. I have a set of heavy and light shoes. Is there a way to "read" the shoes and drum for excessive slippage or wear?

Thanks for any help you provide.
 
It's important with the drum clutches to de-glaze them after every race weekend. If you suspect excessive slippage you will probably notice hot spots on the drum or shoes. If thats the case then the shoes are most likely glazed over. I use scotch brite to deglaze my drum and shoes after every race. If you suspect the clutch to be worn out, get a new set of springs and shoes. They're cheap enough for one of them clutches.
 
If the clutch is slipping, consistently, at peak torque, coming out of the tight corners, that would be my clue that it's in good shape. Proper maintenance, as mentioned above, can't hurt.

I have often mentioned a trick I found many years ago. Take a bathroom scale, put it between the front of your kart and a strong wall, with the driver in the kart, start the engine, warm it up, then floor it. Observe the scale reading and the engine RPM. Write them down. If you've ever had your engine on a dyno, you know where, at what rpm, the engine reaches peak torque. 'With the scale test, if the rpm matches the dyno curve for peak torque, you're good. As long as you maintain that slip rate on the track, you're good.

If you don't have a dyno curve, play around with the slip rate until you find the rpm where you get the best reading on the scale.

Are there ways to adjust your clutch if it's not slipping at peak torque?

One other thing, in an article by Pete Muller, it is explained how heavy weights and stronger springs can hold the engine better at high rpm, better than lighter shoes and weaker springs.
 
Thank you...the more I ponder

Thank you both for your comments. The more I began to think it through, I actually believe the clutch may be locking in too soon as the motor sounds bogged down coming out of corners. In that case, I believe I need to change the setting to come in a little later (slower) either through a larger spring (on the white springs now) or changing the setting by rotating or flipping the shoes.

I will definitely be de-glazing the shoes and drum before next weekend. Too bad the weather in Ohio stops us at the end of October. Should have considered the clutch (transmission of a 4-cycle kart) 2 months ago.

Thanks again. Any other comments are certainly welcome.
 
Check your air gap... You need to keep it .060 - .065 if possible and needs shims if it reaches .070..
Indeed deglaze shoes and drum
Cut 3 slots in the shoes.. spread equally,,approx. 3/16" deep
Keep outer edges of shoes deburred and tapered
To shim the shoes,,, many may roll their eyes at this but it works and done it a hundred times + and save many racers a lot of money.

Tear down the clutch to the bare yoke,, on the yoke theirs 2 humps.. Between those drive lugs I call it a valley.. Cut pieces of business card that will fit perfectly in those valley's.. I always used 3m Yellow Glue that's used with body molding work etc.. Other glues should work as well..
Add 1 shim and check air gap.. You can go to 2 shims per shoe.. But that's it.. If 2 shims don't get you back below .070 air gap then replace the shoes.. Just be sure to prep your shoes as described above...
Country Boy Engineering 101..

Your set up should be Heavy shoes with white springs.. You are better off being under on slippage than above..
JD
 
That's the information I was looking for. I know for a fact that my air is WAY over that! I compared them to another set of light shoes I have and the trailing end of the shoe was at least 1/16" narrower than the leading edge of the USED light shoes. Time for new shoes. Thanks a bunch.
 
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