Noram GE Clutch slipping - why??

J

JB-Boozer

New member
This is a racing kart from 1999, raptorIII flathead engine, I bought it almost new, everything is stock for the adult beginner class.

14 tooth clutch sprocket, 59 tooth main sprocket, 11" tall tires (6" wheels, old rules), setup for Barnesville GA...about 9 race days on this setup.
Clutch: Noram GE w/heavy shoes and blue springs...

The kart has been sitting covered in garage since then, everything ran fine when it was put up, but now that I have it back out, It seems the clutch is just slipping, won't grab until get fully underway, gets very hot and smokes.

The only 'modification' since pulling it out of storage, when I cleaned the carb, was remove the black restrictor plate (beginner class). Also I've put on about 30lbs of lead around my midsection.

Looking at the Noram GE settings, it was initially on setting 5 (very smooth gradual engagement, and high inertia starts).
To help fix the slipping, I moved to setting 4 (smooth gradual engagement and high inertia starts), didn't seem to fix it.
http://www.noramclutch.com/go-kart-clutch/noram/ge-sp3.html


I've taken apart, sanded the shoes and drum, adjusted the setting...the 'tars' have enough air, all 4 wheels/bearings spin fine...chain is not too tight, if anything is a little loose.

Please no 'just get a new clutch', sure I know that.

Trying to figure out why something so simple isn't working. Maybe it's just the shoes. Maybe it's just the drums.
I've done alot of searching online, the only issues I found don't seem to apply:
1) Improper gearing causes slip - solution: change gears or tire diameter (my kart is geared race ready)
2) Over heated, won't disengage - solution: get new springs, the old ones have overheated and lost their tension (overheating is not cited as cause for slipping)

Best I can tell, only 2 things have changed on my setup:
1) added some personal weight
2) removed the restrictor plate

to me, neither of those seem enough to cause this...what am I overlooking?

pictures of the clutch:
https://onedrive.live.com/?cid=ef99...CD14D9!2505&authkey=!AAhWUVtzX99_d1U&v=photos
 
"Slipping too much". That's about as vague as you can get describing a clutch. lol. Where are you testing this clutch?

A good clutch will slip at about 3600 RPM on the starts. It will need to get up some speed before it stops slipping. Only a guess, but somewhere around 27 miles per hour. Don't hold me to that, it's just a guess. I'm going to assume you have no tach.
 
Slips at max rpm, gets up to speed very slowly, testing on relatively flat asphalt
specs show it should engage about 2500 rpm
I don't have a tach...but it gets hot as an iron and smokes a little
 
Yeah it's slipping too much if it "gets hot as an iron and smokes a little".
You might need to use weaker springs. More weight and more horsepower works that clutch harder, so it might need weaker springs so the shoes engage against the drum harder.
Look at the shoes closely - look for bluing. They may be too cooked to grab good now. If they don't still look dull grey then you may have to replace them.
Look at the inside of your drum. It should be a little rough to allow the shoes to grab (not be shiny smooth) but also not looking cooked. Try to see if it is still round - I spin the shoe assembly in it while checking that the gap between the shoes and drum remains about the same.

Hope this helps... been a long time since I worked with Noram clutches so take my comments with a grain of salt since I'm rusty (hope your clutch isn't rusty though).
 
are you trying to ride it on a grass surface?
If those pics are after you sanded thes hoes you need to re sand them.
14/59 is a bit high for a gear got a 65-69 to try.
them springs look pretty stiff. sometimes the color chart and springs do not seem to match.
I would try new different springs.
 
It Was On 5, But I'd changed It To 4. Do you think going to 1 would help?
It all worked fine the day I put it up years ago, so the springs would've had to stiffen over time, i don't know if that happens with steel(?) And the gear ratio was appropriate for the Barnesville track (acceleration over top speed) I never had any slip before

those pics were before sanding. ..After sanding it looked like shiney new scuffed metal
 
no springs do not gain strength.
were you testing at the track?
you don't have it clocked wrong by chance, inboard vs outboard?
like you say its a pretty basic clutch.
 
Last time it was run was a race, ran like all the others..Idk about memory, it was in my grandfather out back garage covered by tarp, he turned the crank over about every month to keep from seizing etc, motor runs fine, enough to slip the clutch out

I'll have to max out the clutch setting and see what happens, but it basically doesn't 'go' , it's not some yard kart left out under an eve of a shed, its a racing setup stored properly, that's what's confusing...I'd expect the carb to junk or the tires to flatten or motor to seize, but the clutch should work if nothing is rusted, right
 
I'm starting to think the engine may be bogging under load and just getting up to the clutch engagement RPM, I've made a video and posted, let me know what you think.
First part is going down, slight hill, then turnaround and back...
I'm at WOT all the way.

[video]https://youtu.be/jGEZbHs3jpc[/video]

Also added couple more pics, and spark plug, does it look like it's running lean?
 
My pilot an I have ran these clutches the last few years and have really done well with them. The blue springs are what we raced in our clutch also. Your video shows you are bogging down. I would change the clutch setup to 1 and put a bigger gear around 64 - 66 on the rear. You will notice an instant change in takeoff and more pull in the mid to upper rpm range.
 
Thanks VPGoldenBoy.
btw - this is same setup I used to race with, same flathead with this same gear ratio, same tires too.
I'm sure a quicker ratio could help, but my concern is why would it be bogging now, when it never acted like this back then...so my concern now is that something is actually wrong with the engine or maybe spark...? I wouldn't want to cover up a real powertrain issue with bandaid.
Also, Slade at Atlanta Motorsports Park has recommended a 17 or even 19 tooth clutch sprocket with my existing 59 rear sprocket (which is even taller gearing) plus that track has a serious hole to climb out of in one corner. As it is now, this thing can't hookup even on a slight decline of a hill lol !!

while it was in dry storage for several years, wrapped up, my dad told me when he picked it up from grandad's, it was leaning up against the wall when he picked it up. Maybe sitting in this orientation with old oil in it did something internally?

Also on the video I noticed something I didn't hear while doing the test - there seems to be alot of 'popping' going on, does that sound like detonation? My spark plug looks grey/white, I've updated the picture file with the spark plug and some 'after' shots of scuffing the clutch with some sandpaper. Does the plug look like a lean condition?

https://onedrive.live.com/redir?resid=EF997A0CE0CD14D9!2505&authkey=!AAhWUVtzX99_d1U&ithint=album,

In the video ( https://youtu.be/jGEZbHs3jpc ) the first part is going down a not very steep hill, followed by coming back up same incline. I don't hear it hook up even downhill until just before I stopped. I was WOT pedal down fully for both runs.
 
You must log in or register to reply here.
Back
Top