new to jackshafts

[getting kart smart]

I recently built a cart and wanted to put a jackshaft on for ease of changing gear ratio. I have a previous thread on here about it but I will just start over. I built a jackshaft bracket, hooked up the jackshaft which is 5\8" I have both sprockets on the same end of the jackshaft but they are both close to the bearing. The furthest one out is about 3 1\2 inches away from the bearing. Problem I am having is when I am torquing up the jackshaft flexes and a terrible grinding sound like I am jumping teeth. Is my jackshaft not thick enough or do I have to have a sprocket on each side of the jackshaft? Should have spent my money on a TC

 

[landuse]

Post a pic of your setup. I am having a problem trying to visualise it.

 

[OzFab]

I'd say that's exactly what's happening; the shaft is flexing either because it's too weak or the bearings are too close together

If you really want the two sprockets together, anchor the shaft at either end; that should eliminate any flexing.

Just for curiosity's sake, post some pics & measurements: distance from sprocket to sprocket, sprocket to bearing, bearing to bearing & overall length

 

[spyder1968]

could be chain not straight in line with sprockets, or too loose also. that makes terrible noises.

 

[getting kart smart]

pics of the kart

This is my first kart build. I used 1 1\4 sch 40 pipe. Bit of an overkill and heavier but I wanted some meat to weld to. (beginning welder) And using an arc welder at that. 100% built by me and not understanding the grinding sound I'm hearing. Hopefully the next one gets a bit easier.

 

[getting kart smart]

Oh, and by the way, this is a great site with alot of very helpful people on here. I see spyder, landuse fabroman and toystory amongst others on just about every post I look at. I know it has to take alot of your time going through every post. Thanks to you all for making this a great website. I couldn't have built this kart without all the stuff I learned on this forum. Thanks again guys.

 

[Doc Sprocket]

You really need to support that open end of the jackshaft, outboard of your sprockets. While you are doing so, ensure that the chains have sufficient slack.

Pictures make things a little harder to read, but it looks like your primary chain may be too tight, while the secondary chain is okay. If that primary chain IS too tight, that will compound the problem- causing the end of the shaft to flex even more.

 

[OzFab]

Oh, and by the way, this is a great site with alot of very helpful people on here. I see spyder, landuse fabroman and toystory amongst others on just about every post I look at. I know it has to take alot of your time going through every post. Thanks to you all for making this a great website. I couldn't have built this kart without all the stuff I learned on this forum. Thanks again guys.

That's what we're all about; sharing information & experience so others don't have the same problems. It's give & take; we teach as well as learn (well, maybe not so much of the learning for toystory ).

IMO, you could easily & safely move your other bearing to where I've marked in red at the end of the shaft so you have one either side of the sprockets; the longer a piece of metal is the easier it is to bend.

Personally, I would build the jackshaft assembly on to a plate & blot it down on slides (similar to the engine mounts). That way you can adjust the secondary chain & simply move the engine in the same way to adjust the primary

 

[getting kart smart]

GREAT IDEA!! Thats a super easy fix. like i said I am new to jackshafts and I had my mind stuck on my original idea. Another Kudo to this great forum!!!

 

[OzFab]

No sweat, all in a days work, my friend.

Always remember the KISS method: Keep It Simple Stupid

 

[landuse]

Awww....I got here too late.

Do what they said /\/\

 

[OzFab]

LMAO

You still got a mention...

 

[landuse]

LMAO

You still got a mention...

I know. I feel guilty though cos I never really give information that I think is all that good.

 

[OzFab]

I know. I feel guilty though cos I never really give information that I think is all that good.

Don't underestimate yourself...

 

[getting kart smart]

So I switched my jackshaft setup around like Fabroman said and it works great..! No more flexing on the jackshaft and no more horrible grinding sound. Thanks again Fabroman!!!!
Oh, the brake setup I got sucks donkey! Any idea on some cheap brakes that actually work? Maybe I just need a bigger calliper.

 

[getting kart smart]

Also, I currently have a 17 tooth jackshaft sprocket on to help with gear reduction. I think I want to go to like a 23 to 25 tooth for good torque, but can't seem to find any bigger than 20. It's a 5\8 inch shaft. Anybody got any good links? It's 41 P chain.

 

[OzFab]

So I switched my jackshaft setup around like Fabroman said and it works great..! No more flexing on the jackshaft and no more horrible grinding sound. Thanks again Fabroman!!!!

No prob, Glad I could help

Oh, the brake setup I got sucks donkey! Any idea on some cheap brakes that actually work? Maybe I just need a bigger calliper.

Yeah, that caliper looks kinda useless; my bicycle caliper looks bigger than that.

If you have the $, go for a hydraulic setup. You could pick up something to suit for $50 - $100. If not, there's a few mechanical calipers out there that will do the job

 

[landuse]

Also, I currently have a 17 tooth jackshaft sprocket on to help with gear reduction. I think I want to go to like a 23 to 25 tooth for good torque, but can't seem to find any bigger than 20. It's a 5\8 inch shaft. Anybody got any good links? It's 41 P chain.

I am not too sure where you could get, but you could maybe find some with a smaller diameter hole and just have them machines larger and have a keyway put in.

Have you been able to get ant larger sprockets at all? Have they just had an incorrect bore size? I usually buy all my sprockets from an engineering shop.

 

[spyder1968]

check ebay for sprockets. they can usually be had in darn near any bore/teeth combo.

i found my axle sprocket ( hardened commercial grade too!) there. i wanted a 70 tooth in a 40 pitch. found one ...but i did have to have the center bore enlarged and 4 holes drilled in it to fit my sprocket hub. still was cheaper than i expected !
try searching for a martin sprocket...............................
http://www.ebay.com/itm/MARTIN-ROLL...791?pt=LH_DefaultDomain_0&hash=item4ab34464af

 

[spyder1968]

Believe it or not, Amazon.com is a good place to look too. Try searching Martin Sprocket. If you still can not find one, let me know and I will find one for you.