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View Full Version : Driven CVT Clutch to Gearbox Mating



SCBaja
10-28-2007, 08:33 AM
I'm working on a small buggy in the SAE Mini Baja Design Competition, I know there are a few Baja veterans on this board, and a great deal knowledge outside SAE Baja as well. *Our team is considering the use of a high/low/reverse gearbox from an ATV. *The first step in the drivetrain will be a CVT configuration; a drive clutch on the engine output paired with a driven clutch on the input of the gearbox; The problem is, our driven clutch is keyed, and the input shaft for the gearbox is splined. *I was wondering if anyone has any experience with dealing with this problem, and any advice on how to adapt the driven clutch to mate with the gearbox without destroying it.

Thanks,
Steve

Philabuster
10-28-2007, 04:08 PM
Simplest solution (read--cheapest) would be to make the original secondary that came with the gearbox work for your application. *Sounds like this is a Polaris gearbox.

SCBaja
10-28-2007, 07:50 PM
Yeah, buying a polaris secondary is a possibility; we were also thinking ofpulling out the input shaft and trying to turn the splines down smooth, make an adapter, and weld it up; not sure if we could do this without damaging the saft. *The only non-invasing thing I can think of would be having our secondary running on its own shaft, supported by two bearings, and some sort of coupling from that shaft to the splined input of the gearbox. *I'll probably get with our machine shop guy and get his opinion too. *I think this is goign to be the biggest hurdle with our design.

hero_saku39
10-28-2007, 08:08 PM
driven clutch off of the smaller 4 strokes from early 00's is only about $300.00

Philabuster
10-28-2007, 08:19 PM
Yeah, buying a polaris secondary is a possibility;

Used Polaris secondary clutches go for under $50 on Ebay all the time. *I bought a new one for under $100 a few months back. *You can adjust spring settings fairly easily or get different helixs and the best part--IT WILL BOLT UP.

Don't ruin the input shaft and delay your build when you could easily solve your CVT issue with the correct parts.

Bugpac
10-28-2007, 08:24 PM
I agree, pm renegade spec, he likely has a polaris driven, dunno if its an atv driven or if a snow machine driven is the same or not tho....

minibajaman
10-28-2007, 10:00 PM
Yeah, buying a polaris secondary is a possibility; we were also thinking of pulling out the input shaft and trying to turn the splines down smooth, make an adapter, and weld it up; not sure if we could do this without damaging the shaft. The only non-invasing thing I can think of would be having our secondary running on its own shaft, supported by two bearings, and some sort of coupling from that shaft to the splined input of the gearbox. I'll probably get with our machine shop guy and get his opinion too. *I think this is going to be the biggest hurdle with our design.

If you are using a Polaris gearbox then you might as well use the Polaris CVT as well. *It would not be worth the effort to modify the shaft as you are suggesting. *The input shafts are I believe hardened somewhat which would make machining difficult and welding not a good idea. *And you can get the Polaris parts thru the sponsorship way cheaper than anything else. *Don't do a jackshaft just to run a different clutch, too many extra parts to break.

I'm assuming that you are looking to use a Comet or CVTech CVT instead. *The team I was on used Comet the last couple years, they work pretty well, but are less tuneable than the Polaris or CVTech. *Many years ago the team actually used a Comet primary with a Polaris secondary, and it mostly worked ok but the Polaris would always break the plastic buttons inside. *I don't think many teams running matched sets have this problem, and the Polaris clutches may have been improved since then. *I would say if you are set on using the Polaris gearbox then go with a Polaris CVT set as well.

desertkart340
11-01-2008, 08:08 PM
We are working on a desert kart with a arctic cat 340 f/c. I'm interested in what polaris gearbox you used. How did you mate the half shafts to the gearbox??

Help needed

Charlie

umbaja2009
11-02-2008, 12:58 PM
In order to solve this problem on our car, we built our own sedondary. But I think you would have the best luck building your own input shaft to the Polaris gearbox if you want to still use your secondary.

nutz4sand
11-02-2008, 01:12 PM
I'm working on a small buggy in the SAE Mini Baja Design Competition, I know there are a few Baja veterans on this board, and a great deal knowledge outside SAE Baja as well. *Our team is considering the use of a high/low/reverse gearbox from an ATV. *The first step in the drivetrain will be a CVT configuration; a drive clutch on the engine output paired with a driven clutch on the input of the gearbox; The problem is, our driven clutch is keyed, and the input shaft for the gearbox is splined. *I was wondering if anyone has any experience with dealing with this problem, and any advice on how to adapt the driven clutch to mate with the gearbox without destroying it.

Thanks,
Steve

Can you post a pic of your input shaft and the driven clutch you wish to use? More importantly measure the diameters of the tranny shaft and the inside of the secondary and post them on here. Being most Bajas are running 10 horsepower or close this below should handle the power pretty effectively.

IF you have enough diameter you may be able to take a clutch that fit the tranny in the atv it came out of and simply machine down around the splines till it fits inside the drivens diameter of your driven then simply cut a keyway to match keyway of the clutch. I think I said that clear enough you should understand it. If not I can get more into detail.

If you have the diameter available this would be easy to do. Getting a old or worn out clutch off the atv for the splines should be cheap.

Post the pic and measurements anyways. It might help someone help you.

sodman
11-03-2008, 04:49 PM
If you are using a Polaris Transmission using a stock cvt from polaris you have to use their primary as well be cause of the pitch of the the belt only fitts polaris cvt. Found this out on my build i'm using 500 4 wheeler motor and trany. One good thing about this set up is the cvt has a engine brake on this set up which on my buggy seem's to work really well. I was told that you could not mix the primary and secondary up I think I new i paid around $500.Canadan for both including the weights for the primary inwhich they told if it had to be reweighted no charge. Have had buggy out twice be for ripped down for paint works great.
Blair (sodman)

nutz4sand
11-03-2008, 04:56 PM
I did not know that Sodman. Thats good to know. About the pitch of polaris being different.

jonzer12
11-05-2008, 08:22 AM
I graduated in 2002 so my info may be dated, but I am running a polaris setup in my personal-minibuggy
You do not want to mess with this on the gearbox side. Polaris has stated
(an most teams that have run plaris setup will agree) to mini baja teams that the best solution is to bore a polaris clutch to 1" and broach in the 1/4 keyway. Polaris has a small mini-baja website (can't find link) that offers registration forms, price sheets for teams, and a faq that deals with clutches, etc. It even has tech diagrams for the clutches, part numbers, etc. I will check my home computer when I am off work to see if I have the link there.

LiveWire
11-05-2008, 11:28 AM
If you are using a Polaris Transmission using a stock cvt from polaris you have to use their primary as well be cause of the pitch of the the belt only fitts polaris cvt. Found this out on my build i'm using 500 4 wheeler motor and trany. One good thing about this set up is the cvt has a engine brake on this set up which on my buggy seem's to work really well. I was told that you could not mix the primary and secondary up I think I new i paid around $500.Canadan for both including the weights for the primary inwhich they told if it had to be reweighted no charge. Have had buggy out twice be for ripped down for paint works great.
Blair (sodman)

A Honda Pilot uses the same belt as a Polaris quad. I don't know of anyone having belt issues with the stock driven and Comet 102C, Power Blok or Quick Shift drive clutches. There are also people running Comet drivens, but it is rare due to the same problem this guy is having, splined input shaft.

jonzer12
11-05-2008, 03:34 PM
SAE SPONSORSHIP PROGRAM (http://www.polarissuppliers.com/sae_team/Polaris_SAE_Sponsorship.htm)

There is the link I was refering to. Very valuable info for what you are looking to do.

"QUOTE"

How should we mount the P90 clutch to our engine?
I would recommend boring the clutch to the correct diameter and depth (1 dia X approx. 3.75 depth) and then broaching the keyway. The 1 bore will not clean up the entire original taper, but if you hold the diameter tightly, you will have plenty to pilot on. I like this method better than making an adapter or modifying the crankshaft.

desertkart340
11-06-2008, 02:19 PM
The driven cvt I'm using measures 3/4''diameter with a 4 1/2''inch keyway. It's made by comet and the model is a 90d. I'd like to use a polaris p-90, comet 790, drakart, redline revolt, or honda pilot fl400 transmission. Let me know if you have one. The engine is a Kawasaki 340 f/c out of a 1971 arctic cat puma. This kart wont be in the mini baja because the engine is pushing 30 horsepower.

Thanks

Charlie

LiveWire
11-06-2008, 04:33 PM
You could use a Polaris quad trans and driven clutch. An FL350 trans would be cheaper than a Pilot one. It has a 7/8" keyed input. You could probably find a gear box with a clutch. Comet makes the replacement driven. I know someone parting an FL350 that has a good trans and driven clutch.

desertkart340
11-07-2008, 03:34 PM
You could use a Polaris quad trans and driven clutch. An FL350 trans would be cheaper than a Pilot one. It has a 7/8" keyed input. You could probably find a gear box with a clutch. Comet makes the replacement driven. I know someone parting an FL350 that has a good trans and driven clutch.

Do you know how much he wants for it?? Another issue is how am i going to mount 930 cv joints to that??

LiveWire
11-10-2008, 06:25 PM
Do you know how much he wants for it?? Another issue is how am i going to mount 930 cv joints to that??

He wants $650

I am fairly sure the spline output of the FL350s trans is the same 400ex hubs. You could weld the cup for the CV to a hub. I think the FL350 U-joints will handle more angle than a Porshe 930 CV. You would have to make plunging axles.

Jerm
01-31-2014, 03:33 PM
hey guys I was going to start a new thread but this one covers alot of it, I realize its a few years old. I had another question. It was discussed that a polaris primary clutch is needed with the driven clutch on the trans, but I also read that some have used a regular comet clutch and it worked also. I bought my 18hp vanguard engine with this clutch on it, I think its a 500, not 100% sure. (can someone tell which one it is)
I'd like to just use this with a trailboss transmission and driven clutch but now I don't know if I can use this comet 500 clutch on the engine. The polaris primary clutch won't fit my engine and I don't really want to get into custom adapters or machining.

http://farm6.staticflickr.com/5519/12242353234_e7d5aacd39_b.jpg