Overdrive Your Pimary Gear?

[Turbo Tim]

[edit by Tork] Note, this thread was not started by TurboTim even though it looks that way due to the result of a thread split

Oh yeah, another thing... overdrive your primary and gear it WAY down. I've got this RX1 running 23/42 gearing and IT ROCKS. Holeshot is unbelievable.

L.B. ............Where would I reference information about "overdriving" the primary ? I don't need as much top end as I have for Mountain riding , I'm running The mcx turbo at the 310 Hp Level . Top end of 110 mph would be plenty .(Any more than that would probably not be too safe for a 162 track anyway)[/b]

 

[LazyBastard]

Pull the belt cover and belt out, start the engine, and with a flat file, start cutting away at the center of the faces on the primary to allow them to come closer together. Let the engine do the work. Its your call on how far you want to cut. Don't blip the throttle when you're doing this.

 

[Srxspec]

Pull the belt cover and belt out, start the engine, and with a flat file, start cutting away at the center of the faces on the primary to allow them to come closer together. Let the engine do the work. Its your call on how far you want to cut. Don't blip the throttle when you're doing this.

LB, I mean no disrespect, but if you want to kill someone, keep recommending the above instructions!! This clutch modification can cause very serious damage if not done correctly!

Lets take a look at clutching efficiency involving overdrive while we're here. Gearing and clutching go hand in hand, changing the one affects the other. When you go to a lower numeric ratio you are keeping the belt lower in the clutch and add to the efficency of the clutch system if all parts go hand in hand. So by looking at a given sled, lets say with 145hp like a RX-1, if you run the sled at 1:1 ratio in the clutching, its going to be very efficient and transfer more of the available power to the track. When getting into overdrive on the clutch's you lose approx 10-12 percent of the clutch's efficiency. It simply takes more power to run the same mph in a given distance. In short by running in overdrive you are only applying roughly 126hp to the clutches by running your belt all the way up in the primary and low in the secondary (overdrive). The reason for this power loss is the belt goes through thousands and thousands of cycles of stretching and contracting and by bending the belt to a tighter radius it creates more heat from friction and slip caused by belt to sheave area contact loss. The smaller the bend the less area of the belt your hanging on to.

TurboTim, if you want to get your primary cut for overdrive, I can cut it. If you have a lathe and some machining experience you can do it fairly easily yourself also. It will cost about $50 for me to machine it for you and I would recommend getting it rebalanced also. Please do not go at it with a file like LB has suggested above!!

 

[dirkdiggler]

Pull the belt cover and belt out, start the engine, and with a flat file, start cutting away at the center of the faces on the primary to allow them to come closer together. Let the engine do the work. Its your call on how far you want to cut. Don't blip the throttle when you're doing this.

Seems like a very bad idea to me.


Tim there are many people out there that cut clutches with the proper tools. Do not use a file. This is a very bad idea!!!!

 

[pro116]

Filing the center away wouldn't that give your beldt more side clearance and result in beldt slippage off the line.That's why they make different size split collars or I must be misunderstanding the was lb is doing it?

 

[Srxspec]

Ryan, what LB is saying is actually cutting the sheaves as well so they can close closer together.

 

[pro116]

got ya

 

[LazyBastard]

There's nothing dangerous about it as long as you don't do something stupid, like get your sleeve caught in it (you can get your sleeve cought in a lathe too), or cut it down too far (you can cut it down too far in a lathe too).

As for 10-12%... not nearly. More like max 2%. You're really not going that far with it.

 

[Srxspec]

Nothing dangerous about it???? What if you take off more material in a spot than another??? What if you go to far and the clutch explodes?? How do you measure EXACTLY how much you took off with that file??

Please people, do not take a file to your clutch. Have a qualified machine shop do it. If you do decide to use LB's method, don't complain when your clutch explodes, dismantles your foot, removes a finger or two, and then shoves shrapnel up into your arm!

 

[dirkdiggler]

I have some experience with this. I went to a large diameter Mega Power Secondary on my 2001 SRX. I had to change my split Collars. They weren't Machined correctly. I was running across a field for a long way and my belt shifted so high in the primary clutch that the weights came over the rollers and smashed the towers. It destroy my Primary and My Secondary. It put holes in my Hood and through my Belly pan. Learn from my mistake.

Send your clutchs to a pro that has machines thousands of clutches so it is done right.

 

[alaskanbowtie]

There's nothing dangerous about it as long as you don't do something stupid, like get your sleeve caught in it (you can get your sleeve cought in a lathe too), or cut it down too far (you can cut it down too far in a lathe too).

As for 10-12%... not nearly. More like max 2%. You're really not going that far with it.

>>>>
That's the dumbest thing I've heard you say ........ that should go on the "suggestions to ignore" list , ..... " how to be a red neck" mechanics 101 ........ NICE ! Just file the bitch.....lmao that's funny as hell... ha ha ha ha

 

[dirkdiggler]

There's nothing dangerous about it as long as you don't do something stupid, like get your sleeve caught in it (you can get your sleeve cought in a lathe too), or cut it down too far (you can cut it down too far in a lathe too).

As for 10-12%... not nearly. More like max 2%. You're really not going that far with it.

>>>>
That's the dumbest thing I've heard you say ........ that should go on the "suggestions to ignore" list , ..... " how to be a red neck" mechanics 101 ........ NICE ! Just file the bitch.....lmao that's funny as hell... ha ha ha ha

LMAO

 

[sledheadgeorge]

this is getting too funny

 

[maim]

i have done this with a leatherman on the lake when a buddys 03 rx1 blew the origonal belt at 10150km. the belt was baked bad and the clutch faces where blue and extremely smooth. we started the motor after all the debreis was out and i ran the file in the leatherman up both clutch faces to roughen them up so it would grab the belt again. wiped with tp to remove grit etc and installed new belt. i got on it later in the day and hammerd the crap outa it and had no problems other than it wouldnt break 100mph. did this cause the clutch faces where so smooth that it was gettin worse fuel milage than my sxr500. after it was makin the sxr700 with us look like a gas hog.

 

[LazyBastard]

Nothing dangerous about it???? What if you take off more material in a spot than another???

Thats not going to happen, the engine is spinning, so the cut will be symmetric.

What if you go to far and the clutch explodes??

What if you do with your lathe?

How do you measure EXACTLY how much you took off with that file??

You start by measuring the space between the clutch faces BEFORE you start to cut, then as you cut, you continue to measure. The amount you have cut off is equal to the initial measurement MINUS the current measurement. I really don't see why that is so difficult for you...


For all you people who don't like to cut down a clutch on an engine....

Lets do a little comparison here, shall we?

What exactly is a lathe? It is a TURNING MACHINE. You strap something into it, and it turns it so you can make a perfectly symmetric cut out of it. What is an engine? It is ALSO a turning machine. Why would you remove the clutch from one turning machine and put it into another one that will do exactly the same thing? The only difference is the tool you use to do the cutting in that you might have simpler, no-thinking control over one whereas the other is freehand. Nothing wrong with freehand unless you are completely inept and/or careless. With a very fine file and only spinning the engine at idle (nice and slow), it actually takes a VERY LONG TIME to cut it down, so there is very little risk of going to far by accidentally holding the file on the clutch for too long, and what little risk there is, is only if you are careless.

If you don't think yourself competent to do this modification as I have outlined, then by all means, GET SOMEONE ELSE TO DO IT. Fact is, cutting it freehand while still on the engine can be just as accurate as cutting it on a lathe.