Short Belt Life

[darrelm47]

I have had my buggy for 3 years and I have yet to have a drive belt last a full tank of gas. I have upgrade the variator to the Performance Teflon Coated, up graded the variator fan to the Prodigy lightweight "cooler" fan. Upgrade the variator rollers trying both 8 gram and 9.5 gram. I have broken 3 kevlar belts so I don't but them anymore, I can brake 3 stock belts for the price of one kevlar and both only last an hour or less. I have a pro clutch installed with 1500 RPM springs and I've used both the 1500 RPM and 2000 RPM Power spring. I also installed a "cooler" PRODIGY HI PEFORMANCE VENTED BELL HOUSING. I do operate in a lot of hills. I asked my supplier "Blade Power Sports" what could be breaking my belts so fast and got no response.
What is the average belt life and what could be breaking my belts so fast?

[BuggyMaster]

Does it launch at a pretty high RPM?

[GX150]

My Yerf did nothing but hills and sand with the belt lasting four years before I replaced it due to cracks in the beveled edges. Either you have constricted air flow in to the CVT, the torque spring is too weak or your gearing is too high for your terrain and tires.

[darrelm47]

It has done this since new before any add on parts were installed.
Originally it launched a low RPMs and after 1st belt broke I installed the racing clutch with 1500RPM spings, little better launch but still problems making up my driveway from a standing start. Next belt I installed the 1500 RPM Power Spring, next belt I was told to sand the fins back off of the variator fan because they thought the belt was riding up and hitting the fins and tearing the belt. Next belt I added a new stock variator. Next belt a light weight variator fan and the teflon coated variator, next belt ect . . . The whole drive is upgraded from factory, and yet my last belt lasted a little less than an hour in flat sandy terrain.

I currently have 1500RPM and 2000RPM Power Springs, 1500RPM and 2000RPM clutch springs, 8gram and 9.5gram variator rollers and a new kevlar belt on order. The axle drive greas have not been changed from factory nor have the tires or wheels. When I get the new belt I plan and installing the highest RPM parts I have, so figuring I'll have low enough gearing, should I be looking for some type of restriction blocking the air gaps on the case?
What is the hazzard of running without the case?

[GX150]

Is your axle sprocket stock? I think your gearing is too high resulting in belt slip and destruction. Changing CVT components does not change your gearing only the shift rate between defined ratios based on your final gear set and sprockets.

My opinion of Kevlar belts is they are a high priced band aid that mask another problem. I run stock belts.

[bige]

yes there is another problem if you are breaking belts. remove the stock rubber elbow from the front of the cvt cover and replace it with a piece of scotch brite pad. check the variator and clutch pulley for nicks. how far down in the clucth pulley is the belt?

what buggy do you have? how many teeth are on the axle sprocket

[darrelm47]

Like I posted earlier "The axle drive greas have not been changed from factory nor have the tires or wheels." I'll have to lift it tonight so I can count the actual teeth, but the gears are stock. The buggy is a 2005 Twister HammerHead.
Stock belt or Kevlar, neither have ever lasted a tank of gas.
The both sides of the variator have been replaced trying to resolve, the clutch pulley is stock, last time I had it apart there was no damage, I checked for nicks and warpage. The belt initially rides very high in the clutch pulley. I ran it on the stand without the cover and noted the variator does expand and contract as well as the clutch pulley. When the new belt comes it I'll make a video and post.

[TeamBreakem]

are you absolutely positive your using the right size belt? That could do it for sure...The belt sizes are a little confusing on these buggies to me, unless you have the manual.

[ckau]

Originally Posted by darrelm47

What is the hazzard of running without the case?

without the case your exposeing the variator ,belt and clutch to the elements. greatly reducing the lifespan of all. Plus two of the longest cover bolts toward the rear serve double duty to hold the trans gear cover on. Without these bolts in place you stand a real good chance of creating a leak in the tranny cover
if your suspecting heat as the culprit. Try this trick to reduce internal temps.

[SYCARMS]

Are your pulley's lined up? Behind the variator is that gear still present? Now I seem to remember that in 2005 both Hammerhead and Carter which used a Hammerhead motor used something like a 2:40 gear ratio in the final drive and these buggies would fly but would not climb worth a darn when pushed in hilly areas would go thru belts. The Blade, Kinroad and everyone else used a 3:08 ratio in the final drive. In 2006 both Hammerhead and Carter used the 3:08 ratio. If your pullies line up the needle bearings in the clutch pulley are good I would check the gears in the final drive. Also take the advise given earlier with intake filter removing the elbow and replacing with scotch bright pad. You can run temporarily with the cover off while checking but the cover needs to be on for the cvt to properly cool.

TOM

[darrelm47]

The drive sprocket is 39 tooth, the pinion gear is hard to count without removing the reverse box but it looks like a 14 tooth.
As for teambreakem's post I can only attest that Blade Power Sports sells one size belt 743-20-30 for GY6 150 Buggies. The Kevlar belt is the same 743-20-30. I do have the manual but the part number there must cross reference to some belt only found in China. The kevlar belts fit tight enough I have to spread the clutch pulley slightly to get the belt over the variator slide shaft, the standard belt is a little easier to install.
I like ckau's modification. What do you think aobut this case http://www.partsforscooters.com/169-...ategory=118397
Thanks Tom for the good input. - I thought about teh pulley's being lined up this last time when I was putting it back together, I actually ran without the gear behind the variator because I thought the pullies aligned better without it. I do still have the gear and will put it back in when I reassemble. If by final drive you are refering to axle sprocket to pinion ratio then I believe you are right 39 to 14 would put the ratio at 2.7 and if I miscounted the pinion and it is actually 16 tooth that is 2.4 ratio. I wouldn't know about the buggy ever flying, I've never been impressed with the top speed, but for sure it never would pull up a simple hill from standing start. My driveway is probably a 10% grade and I wouldn't dare stop on it going up. I will put scotch brite in place of the elbow but may I ask how to correctly check the alignment? Before I simple put a wooden dowel on the clutch pulley grove and laid it across the variator pulley groove and sighted it.

[SYCARMS]

The small sprocket is a 16 tooth. I was not refering to the sprockets but the final drive gearing. This is inside the case behind the clutch. You will have to remove the cover held on with 8) 8mm bolts. Knowing that your sprockets are 39 and 16 tooth (39~16=2:44 sprocket ratio) and I believe the 2005 gears in final drive to be 38 and 16 teeth
(38~16=2:38 final drive ratio. Now take the sprocket ratio of 2:44 X final gear ratio of
2:38 = 5:81 ~2= total ratio of 2:90) this ratio is good for top end but poor on hills the more weight in the buggy the harder it is on the belt. Now lets go with the common final drive gear ratio of 3:08 13 and 40 teeth gears. (Sprocket ratio 2:44 X final drive ratio 3:08 =7:52 ~2 =total ratio of 3:76) With this ratio you will climb just about anything with a properly tunned cvt. 2:90 vs. 3:76. I believe this to be your problem. So you will need to pull the final drive cover and count teeth on the gears. You need to put that gear back behind the variator for it supports the variator. With out it the variator hole will waddle out since there is very little support since there is only about a 1/8" step on the crank and is not enough to support that variator. If it wears it will deffinately cause broken belts. Just make sure you install the gear immediately after taking it out of the freezer overnight and tightening the variator nut using a 1/2" impact. This will seat the gear to the full rear position.

TOM

[GX150]

Tom is correct. I had great climbing ability and clutch life because of my 4.62:1 ratio but gave up top speed. (13/40 gear set with 13/39 sprocket set)

[darrelm47]

I counted the gears. I have a counter gear set adding another ratio to the mix.
My clutch drive shaft has a 15 tooth gear on it and that drives the counter shaft gear of 42 tooth. the small gear on the counter shaft is 17 tooth and that drives the final gear of 36 tooth. Not real sure how to add/multiply/divide to get final ratio. Having all of that information where do I get gear sets? I usually buy from bladepowersports.com or partsforscooters.com and I do not see that either carry the type of gears in my buggy. Should I be replacing the final gear sets or the chain spocket gears?
Last question, Tom says to freeze the gear behind the variator, why? That gear is a press fit on a beveled shaft, freezing the gear whould cause the gear to shrink making it harder to press onto the shaft. From a mechanical press fit application shouldn't I freeze the shaft (shrinking it) and heat the gear (expanding it) so the two slip together?

[darrelm47]

IPB of my final gearing.

[darrelm47]

Ok I probably have gone overboard on this ratio stuff, but after much research and actually counting tire rotations to clutch shaft rotations I have figure out the correct formula for gear ratios. The only division is at the gear sets i.e. 42tooth driven gear divided by 15tooth pinion = 2.8 to 1 ratio. Next gear set 36 divided by 17 = 2.1 to 1 ratio. Multiply the two and the ratio is 5.9 to 1 ratio. There is no division at the final ratio. Now in my buggy the final gear ratio is 5.9 and the sprocket set is 2.4 thus giving me a total gear ratio of 14.5 to 1. I verified this by marking the rear wheel and marking the clutch shaft. The shaft turned 14 1/2 turns to one revolution of the tire. That should be an extreme amount of torque (possibly too much?).

[SYCARMS]

Counting the teeth on item# 9 and # 12(small gear) Divide #12 into #9. If I understand your post correctly 42 ~ 17 = 2:47. What you want is a 40 tooth and 13 tooth for a ratio of 3:08. I do have these gears in stock . Give me a call @ 662-301-1563 or e-mail me your number with a good time to call. tom@sycpowersports.com

Tom

[davidjackson3]

I have a Twister Hammerhead with GY6 I purchased 2 years ago and have had exactly the same problems as darrelm47, only 45 minutes belt life!! I have tried uprated clutches, variators and extra cooling with no success, any ideas appreciated.

[bige]

make sure you have the right belt, it takes a 743-20-30 belt. make sure you have them installed in the clutch pulley only about 1/8-1/4 inch down in the pulley

[SYCARMS]

Bige is correct, if this checks out ok and is not the problem, give us more info such as your location, terrain,type of driving,bought buggy new or used, any mods done ect. This will give us hopefully enough info to quickly solve your problem. Remember that we are not there so your description and detail are very important for us to visualise. You can also call 662-301-1563 Mon-Fri 9-5 and Sat 8-12 noon.

TOM

[davidjackson3]

Hi Bige & Tom,
Thanks for your advice so far, here are the technical details:
Twister Hammerhead, 150cc 6YG short case (230mm crs), about 6 years old, bought second hand.
Fitted 115mm variator with 13gm weights, clutch drum 125mm, driven pulley 142.5mm
Spring for driven pulley 54mm long and 97lb load when in low, 39 long and 128lb load when in high.
GEARING: Small sprocket 16 tooth, large sprocket 39 tooth (2.44 ratio). The overall gearing works out to 21 turns clutch drum to 1 wheel turn. When flat out on stand the wheels turn at 610 rpm = approx 38 MPH.
I think the gearing is far to high. The buggy is driven mostly on level grass land, max achievabel speed 15 to 20 mph.
The belt alignement is good +- 0.5mm. The 743-20-30 belt runs 10mm into the driven pulley at idle(new belt, only 30 seconds driving)

WHAT SHOULD I TRY NEXT? Thanks for your help. Best regards, David.

[GX150]

Your variator has roller weights that will fall out of place when a belt fails. If you did not set them back correctly into the variator ramps, it will be stuck in "high" gear. The rollers may also be worn or damaged causing them to hang in the ramps...

[davidjackson3]

Hi, I remove the variator and set the rollers in the correct position every time the belt fails. I have checked the variator operation by running the buggy on axle stands and it works ok, going from low to high as the rpm increases.

[GX150]

What weight rollers are you using? I suggest 10g roller or 12g slider weight for most applications. The sliders will also last longer once you get your belt issue figured out.

Although your HH has the large axle sprocket, I believe that year had a high geared final transmission. The 13/40 gear set will help you with gearing.

You replaced the clutch. What springs are you using for the pulley (main spring) and the clutch arms (set of 3 springs). My suggestion is to use a very stiff main spring (red 2000 RPM) to keep belt tension and speed up "downshifts" while using stock clutch arm springs to prevent excessive clutch slip before engagement.

[darrelm47]

Here is what finally stopped breaking my belts - install the 40 ~ 13 gear set from Tom.

I have sucessfully ran one and a half tanks of fuel on the same belt now. I do not realize any top end speed loss, but the low end torque is 10 times stronger.

Now I can spend dissassembly and reassembly time making adjustments to the springs and rollers to get the best overall performance.

[davidjackson3]

Hi Darrel, Thanks for that I will try the gear set. Are you using the Kevlar belt? Which power spring and what weight variator rollers are you using?

[darrelm47]

No kevlar this time. I had broken 4 of them (they were lasting no longer than the standard), so the last time I put it together was with a standard belt.
Clutch springs are 2,000 as well as the power spring, the variator weights are 9gram.
I drive in the desert lots of sand, I also drive up and down asphalt roads. Torque in the desest is fine since that is low speed, Pulling up a grade on asphalt is poor because it doesn't have any torque at higher speed so that is where I'll be fine tuning the adjustments now that I am not replacing belts more often that I am filling the fuel tank.

[SYCARMS]

Originally Posted by darrelm47

Here is what finally stopped breaking my belts - install the 40 ~ 13 gear set from Tom.

I have sucessfully ran one and a half tanks of fuel on the same belt now. I do not realize any top end speed loss, but the low end torque is 10 times stronger.

Now I can spend dissassembly and reassembly time making adjustments to the springs and rollers to get the best overall performance.

I was about to call you then I read your post . Glad it worked out for you.

TOM

[SYCARMS]

Many think the kevlar belt is stronger then the regular polyester cord belt. Kevlar will withstand more heat and stretches more than polyester cord. I have run both on my buggy with sucess. However when dirt dragging my buggy with constant break torque and acelleration I found the polyester belt will stretch by the end of the evening where as the kevlar does not. If you run in sand, hill climb or drag the kevlar is the better belt and is not necessary for average ridding.

TOM

[davidjackson3]

How do you set your pulley alignement? When idling my belt is 10mm into the driven pulley and perfectly aligned with the drive pulley. Because of the design where the inside of the variator pulley moves outwards and the outside of the driven pulley moves outwards when you go from low to high the alignement goes out of align by about 8mm.
Is it best to set the pulleys so they are aligned half way between low and high?

[SYCARMS]

There is no adjustment of the pulleys. This is how the system should work. At rest the belt should be at bottom of variator pulley, and level to about 1/8" below top of clutch pulley. As the engine reves the rollers are forced centrifically up the variator ramp therefore causing tension to be applied to the clutch pulley which compresses at a controlled rate the torque spring forcing the belt down on the pulley. The variator roller ramp will move the belt outward up the pulley, since the outer pulley half is fixed as the belt tension increases the outer clutch pulley half moves outward as the belt moves down the pulley. The belt should stay in alignment. If not you would have a timming issue with the pulleys to where the torque spring is not in sink with the rollers so that one pulley is moving ahead of the other. This will cause belt slippage creating heat which weakens the belt. It is possible that your torque spring is either weak or broken, or too lite of roller is being used with stock torque spring. Since one can be considered the right hand and the other the left hand the rollers and torque spring should always be changed as a set. Since you posted earlier that you have 13gr. rollers but only made mention of torque spring measurements I can only assume that you are still running the stock torque spring. With lighter rollers and a weak stock spring this could very well throw the alignment off. You will also need to remove torque spring and inspect the clutch pulley halves for free movement as well as inspection of the needle bearings in the clutch pulley. Hope I didn't confuse things and this helps you in determining your problem. If I can be of further help please feel free to give me a call or e-mail.

TOM

[davidjackson3]

Hi Tom,
Thanks for the detailed info, I now understand that it is very important that the variator and rollers must match the driven pulley and spring to get co-ordinated movement. I have 2 variators, a 115mm dia unit marked F.S & FCC-TW & KDU, I purchased this one and it was called a race variator with 13g rollers. The Hammerhead came with a 108mm dia unit marked FJ & AAB & 6YG with 14g rollers, I think this is a std unit.
The question is which power spring and which variator / roller combination do I use?
I have sent you a couple of e-mails about parts please reply when you get a chance plus advise suggested combination.
Thanks for all the advice and help.
Best regards, David

[SYCARMS]

Will do.
TOM