Clutch Problem

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elmt1
Posts: 51
Joined: Thu Sep 12, 2019 4:58 pm
First Name: David
Last Name: Morris
City/Town: Whitefish

Clutch Problem

Post by elmt1 »

My kart is running a lot better at this point but I managed to cause another problem. I sheered the woodroof key on the clutch/ring gear. Half of the key was in the ring gear and the other half was in the crank with both parts pretty much welded in. This happened at the end of the day. The ring gear hadn't been removed in at least 5-6 days of use and the clutch made it through a full day with about 150 laps before it let go. I'm don't have a lot of relevant kart/clutch experience but I don't think heat should have been a factor where the aluminum ring gear grew since it happened on the first lap and the motor and clutch weren't really even warm since I got sent straight onto the track when I got to the starting grid without hardly stopping.

I'm not sure what caused it but I would guess either grease on the shaft when I put it together or I didn't get it tight enough. Since I always clean it with acetone I have to guess that it wasn't tight enough. The strange thing is that the nut never actually came loose. Now I have to clean off the aluminum that is welded to the crank and buy a new ring gear. Hopefully I can clean it off with lye. Fortunately, OTK is next day shipping here so a new ring gear is on the way. I also bought a few spare nuts, washers and woodroof keys. I have tightened quite a few tapers before and it seems like it should have been OK but I am going to start using a torque wrench. That is the next question. The manual says 4.5 NM, which is 40 inch lbs. That seems way off, so I looked at the KA100 manual and the same nut on their motor says 30-40 NM. Maybe they meant 45 NM? Also, I wonder if it is a good idea to re-torque when it is warm after going out once.

Another thing I noticed in the manual is that it says the piston clearance should be .09mm then later it says start with a clearance of .12 and if it is over .145 it needs to be rebuilt. I am not going to be taking on that kind of project at this point, but it seems like it should be a single number and not take your pick .12 or .09 to start.

Thanks!

evannadeau
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Last Name: Nadeau
City/Town: Calgary

Re: Clutch Problem

Post by evannadeau »

Sorry to hear about all your troubles. I'll be new to the class this coming season, so I'm glad you are finding all these issues in the manual.

I just had a look at the manual myself, and unless they are talking about a specific way of measuring that is not explained, that 0.09mm for piston/cylinder clearance in the maintenance section certainly seems off. Especially when new it should already be at 0.12mm.

And for torque specs, I think that the manual is wrong on all the numbers. Watching the official assembly video, I jotted down these numbers. They didn't torque the clutch in the video, but going by this, the manual has decimils in there when they shouldn't.

Crank Halves - 12 NM
Starter - 12 NM
Intake - 12 NM
Head - 16 NM

Good luck with your repairs.
VLR #42

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Fred
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Re: Clutch Problem

Post by Fred »

I don't quite understand how we are having these problems . I have been involved with this motor since its inception into NA. How many hours do you have on this motor ? The only torque setting I ever use (and I've rebuilt many many of these motors) is on the head nuts to set the squish 16Nm . Other than that I use a Milwaukie torque gun. I am wondering if you had the concave washer in the wrong way when you reassembled it as this makes the clutch very hard to turn and would probably build up heat. I have only ever squidged one key because it was not set in the groove completely square. The clutch bearing is the only thing that needs a light lubrication at the end of the day (very light).. Lucas assembly lube is the best by far for this not grease and again a torque gun with a 17mm socket on is all you need to remove the drum. I have never lost a ring gear , a clutch or clutch bearing and we often tear the motor apart at the end of the racing day to clean it.
Take torque values as suspect as in everything Italian they often get the decimal point wrong.
I am also suggesting the piston / Bore values are one without ring and one with ring fitted.. Joey might be able to confirm this.

If you take your time these really are very easy engines to tear down and rebuild .. if in doubt take a photo with your phone at every stage or rebuild from an upside down strip.

elmt1
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Re: Clutch Problem

Post by elmt1 »

Good morning Fred,

The process you described is exactly what I have been following each day I use the kart. I usually arrive at the track at 9:00 and take off the clutch drum. I clean the drum and bearing with brake cleaner and then blow out any dust in the clutch. If there is any glazing starting to form on the pads, I scuff that off with emery paper. I also blow out all of the dust. Then I use a small amount of moly grease on the bearing and put it back together making sure to get the washers right. I have been using a Makita impact gun but have used the Milwaukee's side by side (both of my sons have Milwaukee), and I am pretty sure they are comparable. That is how I did it when the woodroof key sheered at the end of the day. I also check the chain to make sure it hasn't stretched beyond the go/no-go limit. I have done this about 30 times now so the process is down to about 10 minutes. I do this every day because if I don't, the clutch starts to catch and make noises. Frequently it is at that point of making noise at the end of the day when I go home if I was able to get in more than about 12 sessions.

Your right, that I am a complete newbie when it comes to karts and I expect a learning curve and mistakes. I didn't even know go-karts still existed and were a thing until three years since the last time I was attracted to karting was about 40 years ago when I would ride my bike to Bug Karts in California. At that time I had no money and would just go through their garbage to collect parts for an old at the time, sprint kart that I put together from a discarded frame and a lawn mower engine. Three years ago I went to a conference and they had a karting evening at K1 speed. Since then I have been addicted and started out renting various types of karts at about 25 tracks around the world. I only bought my own kart a little over a year ago but Covid19 made it impossible to use it in Calgary where I hoped to learn the ins and outs of kart setup and racing. I was able to go to 7-8 races in Montana but those were pretty low key events where you didn't have practice days or even much practice and races were about 5 minutes long. Because of that, my only real concentrated driving experience was renting either a LO206 or a Rotax kart for a day, which I have done about 6 times over the last 2 years.

This year, I moved to Ocala and have been going to the track every day off and any afternoon that I could get out of work early. I am usually the first one there and the last to leave and have been systematically trying different setups with my kart. I have a lot of catching up to do. I try widening, narrowing, changing camber, caster, toe, wheels, etc. just to learn what the impact is. I generally just end up back at the base setup but I have learned a lot. During that period, I have put in a couple of thousand laps and have worn out 3 sets of dry tires new to cords (including the vega greens I bought last year for Calgary) and 1 set of wet tires along with about 40 gallons of fuel. Most days there are a few people at the track unless a team comes for the weekend and sets up a big tent. On those days there can be 30-40 people on the track. Strange thing is that the race fields here are very big for 206 but very small for KA100. However, the only people that seem make it to the track regularly have 2-cycles. The ratio of people practicing on any given day with 2-strokes to 4-strokes is about 40-1. However, the race program guy at Ocala recommended that I switch to 206 because the ROK isn't used here and even if they let me race with the KA100s I would be mixed with the juniors because there are only a couple of senior KA100 drivers left this year after Covid19 wiped out the season here last year.

Thanks!

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Fred
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Re: Clutch Problem

Post by Fred »

Bizarre
That must only be at your local track as VLR is big in Florida .. look further afield .

Unless I can stand and see, or strip down your motor I cant really recommend anything else ! The washer I am referring to is the big concave one that fits behind the clutch .. if this is in the wrong way the motor is hard to turn over and the clutch constantly engages.
Also check your tick over .. does the kart try to jump forward when you sit and idle ? (Clutch engaging) If the clutch make a horrible grinding screeching noise this is because the grease you are using has been flung off the bearing ..... Use Lucas green machine lube not grease..... Also to aid in cooling the clutch insert 3 10mm nuts between the sprocket chain cover and the casing so air flows around it.. you may need slightly longer socket head bolts to achieve this. Seems like you are putting lots of hours on it though.
If you have not rectified the low rpm problem change the crank lip seals.

elmt1
Posts: 51
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Last Name: Morris
City/Town: Whitefish

Re: Clutch Problem

Post by elmt1 »

Good evening Fred,

I really appreciate your insight here. The only thing I can come up with is that I didn't tighten the larger clutch nut tight enough. I used my Makita impact gun like I have always done when I put it back together this weekend, and with a large breaker bar and the ring gear locking tool, it feels pretty tight. Unfortunately, during my move to Florida, I put my larger torque wrenches into a box and I can't find them to see exactly how tight it was but it seemed plenty tight They don't actually list a torque for that nut but I would guess I had it at about 60 ft lbs. I also know now that the outer nut has nothing to do with this coming loose so it was on and tight for at least 10 days of hard use before the woodruff key sheered off. I can see that the woodruff key was installed correctly because I have a perfect half moon that was left in the crank and another half moon that is missing the chunk from the crank that I extracted from the ring gear.

Until I figure out exactly what happened, I will be re-tightening that inner nut after I run it for 30 minutes or so to make sure it is seated on the crank shaft properly. Since I put it back together on Saturday, I have put a few hundred laps and no issues. They have the Winter Series ROK race here in a week. The first of the Winter Series that was held down in South Florida only had about 20 total Senior/Masters ROK VLR entries so I have to guess that the change to ROK only may have fragmented the class here. I really hope that I can stick with this class because the next step down (lo206) isn't that enticing to me for practice and the next step up (X30 or ROK GP) seem to be quite a bit more expensive to get started in and to run.

Really off the topic. I don't know how it is in Calgary, since I never got to cross the border this year, but for me, it would be great if there were just training days here where you would have very loosely organized races during the week that might attract drivers that are looking for a low-key mixed class setting in a 30 - 45 minute race that would be a lot like the year end enduro. If that happened on a week night, I would be there every week. I am guessing it might be a challenge for insurance and maybe people are worried about wear and tear on equipment. When I raced bikes many many years ago, we had that sort of thing available and it was a great way to learn and improve.

Thanks!

--David

JCraig83
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Re: Clutch Problem

Post by JCraig83 »

I just had this exact same thing happen - were you able to get the aluminum from the key out of the crank? If so, how??

Thanks!
quote=elmt1 post_id=11553 time=1613182007 user_id=1866]
Good evening Fred,

I really appreciate your insight here. The only thing I can come up with is that I didn't tighten the larger clutch nut tight enough. I used my Makita impact gun like I have always done when I put it back together this weekend, and with a large breaker bar and the ring gear locking tool, it feels pretty tight. Unfortunately, during my move to Florida, I put my larger torque wrenches into a box and I can't find them to see exactly how tight it was but it seemed plenty tight They don't actually list a torque for that nut but I would guess I had it at about 60 ft lbs. I also know now that the outer nut has nothing to do with this coming loose so it was on and tight for at least 10 days of hard use before the woodruff key sheered off. I can see that the woodruff key was installed correctly because I have a perfect half moon that was left in the crank and another half moon that is missing the chunk from the crank that I extracted from the ring gear.

Until I figure out exactly what happened, I will be re-tightening that inner nut after I run it for 30 minutes or so to make sure it is seated on the crank shaft properly. Since I put it back together on Saturday, I have put a few hundred laps and no issues. They have the Winter Series ROK race here in a week. The first of the Winter Series that was held down in South Florida only had about 20 total Senior/Masters ROK VLR entries so I have to guess that the change to ROK only may have fragmented the class here. I really hope that I can stick with this class because the next step down (lo206) isn't that enticing to me for practice and the next step up (X30 or ROK GP) seem to be quite a bit more expensive to get started in and to run.

Really off the topic. I don't know how it is in Calgary, since I never got to cross the border this year, but for me, it would be great if there were just training days here where you would have very loosely organized races during the week that might attract drivers that are looking for a low-key mixed class setting in a 30 - 45 minute race that would be a lot like the year end enduro. If that happened on a week night, I would be there every week. I am guessing it might be a challenge for insurance and maybe people are worried about wear and tear on equipment. When I raced bikes many many years ago, we had that sort of thing available and it was a great way to learn and improve.

Thanks!

--David
[/quote]

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