Gearing, tires ... belt & Variator ...

[x-bird]

So, finally gave the old girl her first extended ride session today. about an hour of pretty steady "mixed bag" running. There isn't really anything i can do with the gearing on it because of the size limits of the differential housing. While I'm happy with the low end the engine produces and what seems to be it's top speed, i think the 31 T sprocket with the Rubicon 22 inch tall tires are putting too much strain on the belt when starting off or going up steep or really rough terrain. I don't want to drop back to a shorter tire, because there isn't much clearance for the diff housing.

After one "vigorous" pass through the little gulley that saw the buggy stopped and revving/spinning the rear tires to force the front end up a really steep face on a diagonal, the CVT belt completely disintegrated about 30 seconds later while running at full speed on the flats.

Thankfully, my house is right across the street, so i pushed it into the shade and installed a new belt.

The 4 little air intake holes were pretty well dusted shut, but i don't think the lack of airflow was the only reason the belt went. The belt was brand new but for the test runs i've done, the biggest piece left of it was maybe 3 inches long and the cording was completely wrapped around the clutch. Hardest part of a "field replacement" was the fact that the variator spacer was hot and on the shaft pretty tightly. Tapped it from behind and gently pressure walked it off the shaft from the rear with a couple open end wrenches.

Presently it has 14 g rollers and what is likely the stock clutch setup. Any recommendations on the easiest way to take some of the strain off the belt in low speed situations? Not looking for more top end speed or to even really make it quicker off the line (real easy to catch a tree in my latest ride area--it's that tight) though the latter is what it kind of needs to resolve the issue.

All along I've also been thinking about running an extension off the intake neck up to about shoulder level on the rear frame with a shop vac accessory end on it (the thin, wide floor sweeper fitting). Just wondering if there would be enough pull off the variator fan to make it work.

TIA for any suggestions.

After work i may be able to put up a quickie vid of the gulley followed by the belt going. vid file's been converting for the past hour or so ....

[ckau]

The 31t sprocket with the 22's should not put too much strain on the belt. I use that combo 99% of the time. OEM Stock clutches have always held just as good or better than the aftermarket models. I do use 12G rollers, 14's are a bit sluggish off the line for my taste.
Whats your internal trans gear set combo? Using a 14/41 set will give good pulling power.
running a length of "shop vac hose up to the cage will work good. The air doesn't have to be strong or forceful, The variator just needs a clean fresh source. I got a old uni on the end to filter dust and whatever.
Best thing I ever did was to cut out the center of the plastic clutch plate on a howitt cvt cover. Epoxy in a screen basket to hold some filter material. My cvt cover used to get too hot to touch. This outlet over the clutch cooled things down dramatically

[x-bird]

Think i'll definitely do both the "snorkel" and break out the big holesaw for the cover. 20 minutes after it broke the cover was still hot enough that i was glad i'd brought welding gloves with me to pull the exhaust

transmission gearset is a 13-40 -- I don't know if that helps or hurts.

Once i go beyond a single drive and final sprocket i can't follow which way does what in terms of diameter changes.

What really gets me goofed up is the way the variator and weights work.
It seems kind of counter intuitive. I'd normally figure a heavier weight roller would roll out faster because of centrifugal force and mass, opening the variator more quickly and keeping the diameter smaller, thus turning more easily. but since the variator and clutch then drive the small sprocket followed by the final one, i'm bass ackwards ...


I take it the lighter rollers keep the variator closed a little longer.

final item to add to the mix ... loaded weight is right around the 800 pound mark.

[T3beatz]

You are on the heavy side of the 150's, Stock yerfdogs are a little over 400lb's, crossfire 150 528lb's...

I'd go with some lighter rollers or sliders and if you don't have a heavier contra spring on it I'd get one of those too. It will help to keep the belt from slipping on the clutch a little and help downshift faster also so you will be in a lower gear when coming off the brakes.

I take it that all of your transmission is stock from the CVT on back?

[x-bird]

Clipped a few segments together, including an "ode" to manco & metal's Tall grass videos . that little bit of running definitely helped overheat the cvt, as did the little off kilter ditch crossing later on.

http://youtu.be/7Pb0KXHohFk

[ckau]

Originally Posted by x-bird

transmission gearset is a 13-40 -- I don't know if that helps or hurts..

That gear set combo helps. it's about as good a combo as it gets for pulling power.

[QUOTE] I take it the lighter rollers keep the variator closed a little longer
Exactly! This allows the motor to turn some rpm's into the power band while still staying in a lower gear ratio.

A stiffer contra spring will put extra tension on the belt to reduced slipping and will also force the variator to open faster which in turn puts you in lower gear ratios faster as you slow down.

I tried to explain this principle to a young guy a few days ago using a automotive manual trans as a analogy. As in allowing the motor to turn higher rpms before shifting to put some power down. He looked like a deer in the headlights. It occurred to me that anybody who started driving in the last 10 years probaly doesn't know manual transmissions!
I felt old and also pitied him for never knowing the thrill of rowing a 4 speed through the quarter mile!

[x-bird]

So from looking around, I take it I would probably want the "yellow" spring? The smaller springs connecting the clutch shoe segments i'd want to keep stock or even be lighter, correct?
I'm also wondering if the overall condition of the clutch isn't part of the problem. The clutch bell was blued when i got it from the PO from running it with the rollers jammed up in the variator. the fan was locked up into the CVT cover. I lightly sanded the shoes and made sure the inside surface of the bell wasn't glazed, same for the pulley halves.

[shiftrm131]

Figured it seemed appropriate to post this question here. New to Buggies and just picked up a 2005 JEHM Hammerhead 150cc (apparently identical to a TJ Hammerhead?). I noticed a factory TJ hammerhead has 22in rear tires. Mine currently has 18in with no gearing change (16/39 tooth same as TJ with 22in). Accels great :-) but I want to upgrade the rollers without adjusting my gearing (economy route). What weight rollers do you guys recommend? I heard from the factory they are 14? Should i stick with that or go lower/higher. It will be pushing 200+ pounds of riders constantly. Are sliders worth the extra bucks?

[T3beatz]

X-bird, yes the yellow spring (1500rpms) would be the one your looking for, some vendors sell them in different colors, but it's mostly known as being yellow. the smaller clutch springs depend on how you want the clutch to engage on take off, do you want higher revs before engagement (heavy springs) or lower? Most people just leave the stock ones on and they do just fine.

Shifrm131, With 18" wheels on the back you should have no problems moving 200lbs with the stock gearing. Going with lighter weight rollers/sliders will decrease your top end and give you a little more boost on the low side. Sliders last a bit longer than rollers and transition smoother up the variator. Also, a 12g slider is about equal too a 10gram roller on the low side, and 13g rollers on the high side because of their shape.

[x-bird]

Thanks TJ ...

http://youtu.be/JLI745XGXfc

a little 5 min clip video my drainage ditch mostly drained--hate how that happens LOL --- and the camera angle is still a touch high. In a few spots in the clip you can sort of tell where i'm just sitting with belt slippage and no tire spin. My right side tire is the one that i messed up the bead on, the air pressure gets knocked out of it kind of easily. i slammed the bottom of the ditch a couple times (you can hear the rear frame contact as the travel bottoms out) and bouncing through the ruts left it with only 2-3 pounds in it and ended the ride.

anyone ever use slime on the outside of a bead as well as the inside? it has some pretty nasty tears.

[shiftrm131]

Thanks TJ. Would you agree my best bet would be to purchase 14g sliders to get the best of both worlds with my current gearing. Dont plan on getting bigger tires since 18 are fun in the yard (ground cleanrance isnt an issue).14g sliders would strengthen my low while allowing me to reach higher top speeds? Thanks!

[T3beatz]

X-bird I have not used slime on the outside bead but I have used the tire bead sealer stuff from the local autoparts store. It's black and it goes on with a brush then it drys like rubber it works pretty good. I cant watch the video right now I'm out visitng my girlfriends family and there computer is limited.

Shiftrm131, as far as the sliders go, it all depends, 14g sliders or rollers may be getting you all you can get on the top end, the belt may be riding as high as it will go, but the sliders should help a little on the low end. Also, have you done any other mods to the engine? like CDI, coil, or intake upgrades? Those are simple cheap mods that can get you some extra HP and a few extra MPH.

[ckau]

Originally Posted by x-bird

anyone ever use slime on the outside of a bead as well as the inside? it has some pretty nasty tears.

leaking around the bead? Pop the bead loose from the rim. run a bead of silicon caulk around the rim where the tire bead seats. pump up the tire to set the bead to around 12 to 15 lbs. let set overnight then deflate tire to proper pressure. This helps on older tires where the bead has been stretched and also helps to keep the tire from spinning on the rim.

[x-bird]

only leaks when i really lean on it in left turns or land flat and hard or angled on the right. if i push on the sidewall with my hand, it will let air out. otherwise it holds air fine, no slow leaks. I may actually use rubber cement on all the flaps where there are tears, let that dry then try the caulk for a final filler seal against the rim. otherwise it's time for a new tire.

[metalstudman1]

I've used both the bead sealer and the silicone & both work well-IMO- bead sealer seems to last longer though (in my experience on new tires) when doing stuff like donuts continuously where I'd have to re-treat the silicone. When I used the bead sealer I didn't over fill the tire and let it set un-loaded overnight for the best result.The bead sealer doesn't really dry up like silicone and keeps the bead tears pliable. I use slime in all my tires regardless if new or old- it just keeps on working!! I doubt slime would do much on the outside since it's water soluble and would just wash away with just a small amount of condensation. I've only had 1 flat tire in the past 4 years while out driving(sidewall slash)- but many overnight flats that aired right back up without going flat again. Now of course the real cure is beadlocks!!! A beadlock don't care if there's small damage to the outside of the bead.

[shiftrm131]

TJ,

My buggy is completely stock (even the stock airbox). I went with 14g sliders and gpsed 25 today (remember I only have 18in tires). I assume thats the best I am going to get unless i do some mods. Thing rips on the low end side. Whipped it sideways in the yard and got it on 2 wheels! :-). Im happy with it for now. I can definately tell a difference with the sliders

Casey

[metalstudman1]

shiftrm131- getting up on 2 wheels made you smile:-) ?!!!!!

[shiftrm131]

Haha it did. I've rode 3 wheelers all my life (200x,350x, and 250r). So getting a full caged buggy up on 2 doesnt bother me. There is no longer grass in my front yard but that's life.