2-Speed clutch problem

#1
After almost a year of restoration I finally rode the 1970 Fox Trail Tramp. Started 2nd pull but immediately felt drag and heard noise from 2-speed clutch. The clutch, big 2 speed gear, bearing inside big gear, small gears all NOS genuine parts. Chains are exact pitch length according to factory manual. The new clutch was missing the copper or bronze insert bushings that ride on crank shaft so I used the old ones. Other than that all new. Plus a member here sent me pics of a 2 speed setup right off an original Fox so pretty sure all clutch parts are correctly installed.

When you roll the bike clutch drags and makes moaning noise plus when engine running but sitting idle both sides of clutch are grabbing and moving bike. I almost lost bike a few times when starting clutches engaged immediately and bike lurched forward!

I didn't lube the clutch that much besides those bushing so not sure if it needs more lube?

Any ideas greatly appreciated. Thanks in advance
 

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pomfish

Well-Known Member
#2
Learned a long time ago to put your bike all the way against a wall away from traffic in case it gets loose, then try to start it.
This goes for any mini bike till you know you can trust it.
Whacky Governors, grabby clutches, stuck throttles have seen it all. It's the only safe way to go.

That said, with your deal as you have described, Everything is new and not worn in yet.
Lube any bushing but sparingly.
Need to put miles on it. Lots of stops and starts get everything up to operating temp and get it all run in.
Really think the grabbyness will subside after doing this.

HTH and good luck
Keith
 
#3
Learned a long time ago to put your bike all the way against a wall away from traffic in case it gets loose, then try to start it.
This goes for any mini bike till you know you can trust it.
Whacky Governors, grabby clutches, stuck throttles have seen it all. It's the only safe way to go.

That said, with your deal as you have described, Everything is new and not worn in yet.
Lube any bushing but sparingly.
Need to put miles on it. Lots of stops and starts get everything up to operating temp and get it all run in.
Really think the grabbyness will subside after doing this.

HTH and good luck
Keith
Thanks for the tips. I will take onto lawn to start, this way it won't mess up the paint if it gets away. Plus I'll lube a little more and ride it some more.

I have the old clutch and was thinking about putting that on just to see if any difference.

Was also thinking about what you posted with governor, etc. If the engine is revving too high will that cause clutches to want to grab?

Take care
 

pomfish

Well-Known Member
#4
Oh Hell Ya!

That's their job to grab at higher revs.
Ultimately we want to set idle settings with clutches hooked up for some natural drag, but if you think you have a problem you may have to resort to pulling clutch till you get gov. sorted out.

Start by backing off throttle stop screw a 1/8 of a turn at a time, go from there.
Is this engine a fresh rebuild or has it been used successfully before?

Markus can probably help with gov settings, He knows his sheet better than most of us including me.
Nice looking bike by the way!
 
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#5
After almost a year of restoration I finally rode the 1970 Fox Trail Tramp. Started 2nd pull but immediately felt drag and heard noise from 2-speed clutch. The clutch, big 2 speed gear, bearing inside big gear, small gears all NOS genuine parts. Chains are exact pitch length according to factory manual. The new clutch was missing the copper or bronze insert bushings that ride on crank shaft so I used the old ones. Other than that all new. Plus a member here sent me pics of a 2 speed setup right off an original Fox so pretty sure all clutch parts are correctly installed.

When you roll the bike clutch drags and makes moaning noise plus when engine running but sitting idle both sides of clutch are grabbing and moving bike. I almost lost bike a few times when starting clutches engaged immediately and bike lurched forward!

I didn't lube the clutch that much besides those bushing so not sure if it needs more lube?

Any ideas greatly appreciated. Thanks in advance
The clutch hat/bell bushings worn or under-lubricated will cause all of those symptoms. I'd check the idle speed too but the moaning while rolling and not running is probably bushings.

The pictures make it look like there isn't alot of crank left for the clutch to float once it's bolted on.

How do you know which side is which on that clutch setup? (I'm asking, I've never laid hands on that 2spd type).
 
#6
when you put the clutch on the pto shaft should extend slightly past the clutch,the washer rest directly on the shaft when bolted down the clutch bells rotate freely.If the pto shaft is recessed in the clutch the washer will be compressing on the clutch stopping it from free wheeling ,I think if you measure the recess you will find 3/4 inch.If your pto is 2 1/4 you will need 3 inch pto crank
 
#7
The clutch hat/bell bushings worn or under-lubricated will cause all of those symptoms. I'd check the idle speed too but the moaning while rolling and not running is probably bushings.

The pictures make it look like there isn't alot of crank left for the clutch to float once it's bolted on.

How do you know which side is which on that clutch setup? (I'm asking, I've never laid hands on that 2spd type).
Thanks for reply. The front half moves free from the bolt & washer. Bolt bottoms out tight to crank. I will double check but think clutch is designed for 2-1/4 standard shaft

I had posted on here about which side of the shoes goes in (one side of center is bigger) but didn't get a response. I tried both ways and don't make much of a difference. The front and back housings & gear sizes are same.

This is what I did today with some success. I didn't have much time but swapped the shoes & front housing with the old ones and bike was much better. Some vibration at top speed but sat idle without grabbing. This weekend going to swap out the complete clutch and put old one in. Will report back but think it will work good.

I'm starting to think the new clutch needs more lube and has to wear in like someone posted here. But how long should wear in take? it is too dangerous with the way it wants to take off when it starts!

Question for anyone that knows this type of 2-speed setup, is the inner chain suppose to engage all the time or only move at a certain RPM?

Thanks again to all who replied so far
 
#9
Thanks for reply. The front half moves free from the bolt & washer. Bolt bottoms out tight to crank. I will double check but think clutch is designed for 2-1/4 standard shaft

I had posted on here about which side of the shoes goes in (one side of center is bigger) but didn't get a response. I tried both ways and don't make much of a difference. The front and back housings & gear sizes are same.

This is what I did today with some success. I didn't have much time but swapped the shoes & front housing with the old ones and bike was much better. Some vibration at top speed but sat idle without grabbing. This weekend going to swap out the complete clutch and put old one in. Will report back but think it will work good.

I'm starting to think the new clutch needs more lube and has to wear in like someone posted here. But how long should wear in take? it is too dangerous with the way it wants to take off when it starts!

Question for anyone that knows this type of 2-speed setup, is the inner chain suppose to engage all the time or only move at a certain RPM?

Thanks again to all who replied so far
Inner chain goes to "1st" gear with the one-way clutch/sprag. The clutch has different engagement RPMs per side, so it does matter which way you install it.
 
#11
These 3 questions came to mind:

1) What type of lube is good for the clutch bushings, dry lube, grease or light oil?

2) Since someone confirmed it matters which way the shoes go in does the smaller springs go toward engine or outside?

3) What chain is suppose to engage first, the inner chain that goes to the big gear with one way bearings or the outside chain?

Sorry if any of the questions are stupid, my only experience has been with TC setup with a belt driving the jackshaft.

Again thanks to everyone for the help.
 
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#12
These 3 questions came to mind:

1) What type of lube is good for the clutch bushings, dry lube, grease or light oil?

2) Since someone confirmed it matters which way the shoes go in does the smaller springs go toward engine or outside?

3) What chain is suppose to engage first, the inner chain that goes to the big gear with one way bearings or the outside chain?

Sorry if any of the questions are stupid, my only experience has been with TC setup with a belt driving the jackshaft.

Again thanks to everyone for the help.
30 w engine oil
1st to engage LG one way sprocket
 
#13
These 3 questions came to mind:

1) What type of lube is good for the clutch bushings, dry lube, grease or light oil?

This what I do. First remove the bushing and spray it all over with brake clean to open the pores in the bronze. then I soak it in a can with 90 w gear lube. Finally, I'll wipe it off and apply very thin coat of wheel bearing grease. It might sound like overkill but I can go a long time without the need to relube and I've never had a problem with oil getting in the clutch.
 
#15
After almost a year of restoration

Its been 3 or 4 years back but a long standing member on the forum posted a lengthy thread about setting up a 2 speed setup. I remember it was a lot of fussing over adjustments and chain lengths.

I want to say it was either Doc or Mr Pat but I cant remember what I ate for lunch yesterday so dont hold me to that...

Hopefully someone else might remember the thread. Seems like it was in a build off.

Wish I could help more.
 
#16
Update, I put the complete old clutch on and right away I felt it was much smoother just rolling the bike. Everything seems to be working good. Appears that the inside clutch half is grabbing first so hopefully pad assembly in correctly. It's hard to tell but looks like both sides of clutch engage shortly after starting out. Thinking maybe weak springs because of being 50 yrs old? Also now wondering if the new clutch I started with was aftermarket and not Fox NOS?

For the one poster who replied, at one point I was wondering about the 2-1/4 shaft but one of the members here measured his Fox original engine and it was 2-1/4" as well. This was same member who gave me all the measurements of the clutch. Very helpful along with all the replies here.

Thanks again everyone.
 
#17
just measured one of my fox clutches its three inches wide you need a three inch pto
Are you certain of that,and did you measure just the clutch or the pto shaft length itself ? I removed the complete 2 speed clutch from one of my totally original unrestored street scamps to take pics and give all the specs to copyman and if I remember correctly my pto length measured 2-1/4.
 
#18
Are you certain of that,and did you measure just the clutch or the pto shaft length itself ? I removed the complete 2 speed clutch from one of my totally original unrestored street scamps to take pics and give all the specs to copyman and if I remember correctly my pto length measured 2-1/4.
I measured the clutch its three inches wide if you put it on a 2 1/4 pto it will be 3/4 inch recessed in the clutch,it cant work the clutch has to float,the pto shaft has to extend past the clutch the bolt and washer is not there to compress the clutch but flush to pto shaft.pto shaft needs to be 3 inch,the outer clutch sprocket will have no support
 
#19
Like I said everything is working good now with old clutch. On the bike now is original engine and clutch that came with the Fox Trail Tramp. Serial # matches with 1970 date code. I was thinking maybe someone changed the crank at some point but when 1971_MB1A confirmed his "original" Scamp's shaft was 2-1/4 that confirmed it. The bolt is proper length (from original manual) and as I mentioned in prior post tightens all the way and front clutch half spins free.
The pictures 1971_MB1A sent me help a lot, I noticed his original clutch had a nice gap in between clutch halves, the new clutch that was giving me trouble had very little gap. This is what makes be think it was wrong clutch or aftermarket.
 
#20
Like I said everything is working good now with old clutch. On the bike now is original engine and clutch that came with the Fox Trail Tramp. Serial # matches with 1970 date code. I was thinking maybe someone changed the crank at some point but when 1971_MB1A confirmed his "original" Scamp's shaft was 2-1/4 that confirmed it. The bolt is proper length (from original manual) and as I mentioned in prior post tightens all the way and front clutch half spins free.
The pictures 1971_MB1A sent me help a lot, I noticed his original clutch had a nice gap in between clutch halves, the new clutch that was giving me trouble had very little gap. This is what makes be think it was wrong clutch or aftermarket.
measure the clutch if its 3inch wide you need a 3 inch pto if you look at your picture you posted the shaft is to short,the pto has to extend slightly past the clutch,If its workin now I think your spinning the bushings in the clutch bells it will come apart
 
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