deekersrx700
New member
I have a 2001 mrviper ported SRX, in 2000 foot speed runs, just wondering if any experienced radar runners have any advice on gearing. Last weekend I ran stock gearing and my best pass was 115.6. I'm 210lbs, should I be gearing down? Not sure what to do, my goal is to run at least 120 in trail form. Any advice appreciated. I'm going to try 22/39 and see on gps what it gives me. Thanks for any advice.
Deeker
Deeker
22-39 is 1.77 ratio.. should be good for 2000 feet.. you can also try teflon spray on hyfax and make adjustments to clutching to make it run 8600- 8700 rpms for speed runs.. for speedruns its good to over rev a bit!
deekersrx700
New member
bump up
gmcsrx
New member
Hey Booger
Don't you have a SRX cover for sale and how much.
Don't you have a SRX cover for sale and how much.
SRXtrafast
New member
Stock gears on 2000 are 23/38. Is it the same for 01? What gears were used for the 115.6?
deekersrx700
New member
gmcsrx good one, small world eh, lol
srxtrafast stock gearing 23/38
srxtrafast stock gearing 23/38
gearing for stock srx is 98-99= 23-37 ..00-02=23-38
and for 600 its 23-39
and for 600 its 23-39
I ran 23-39 on my 02 and it was good for 1000' hit 106.7 on gps, some other mods done, nothing major, found it left some on the table for longer runs though. I have the 39 tooth for sale if anyones interested.
SRXtrafast
New member
deeker,you may think I'm crazy but I think you have enough power for 25 on top. If not defenitely a 24. BTW what's your track lug measure? 1.25" loses some on top.
deekersrx700
New member
stock .92 track
gearing and clutch efficiency
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 140hp like a srx, 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, and it takes more power to run the same mph in a given distance, so in short by running in overdrive you are only applying 126hp to the clutch's by running your belt all the way up in the primary and low in the secondary. The reason for this power loss is the belt goes thru thousands of cycles of stretching and contracting and by bending the belt tighter it creates more heat from friction and contact loss, this is the lesser ability to clamp the belt from reduced belt surface to sheave contact, the smaller the bend the less area of the belt your hanging on to, now also when in overdrive your speeding up the belt. This is also the reason why the belt slips easily or burns when the sled is just starting out, you have hardly any area to hang on to the belt from the tight bend it has in the primary clutch at the beginning of shift ratio, the same thing is happening here at overdrive, just the opposite of starting out!
So what does all this mean? If you run a taller gear ratio, and you have good engine power to begin with your belt will be lower in the primary and higher in the secondary clutch at wide open, the sled will go faster from less frictional loss, but what gear ratio you can run and still maintain optimum efficiency will only be found thru testing!! Try a 24 top, see what happens, is it faster from point a to b? are the clutch's cooler running? are the engine rpm's the correct range? then do it with 25. You have to keep notes and then when your all done, its very simple to calcualte the data and make the appropriate choice as to what to use for a given race distance or speed requirement, the guy with the best tuning notes wins!!
Here is a formula to play with, but you still need to test, this is just a tool to use:
Shift ratio= engine speed(rpm) x drive sprocket pitch diameter = (? ), divided by,
mph x gearing x 336
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 140hp like a srx, 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, and it takes more power to run the same mph in a given distance, so in short by running in overdrive you are only applying 126hp to the clutch's by running your belt all the way up in the primary and low in the secondary. The reason for this power loss is the belt goes thru thousands of cycles of stretching and contracting and by bending the belt tighter it creates more heat from friction and contact loss, this is the lesser ability to clamp the belt from reduced belt surface to sheave contact, the smaller the bend the less area of the belt your hanging on to, now also when in overdrive your speeding up the belt. This is also the reason why the belt slips easily or burns when the sled is just starting out, you have hardly any area to hang on to the belt from the tight bend it has in the primary clutch at the beginning of shift ratio, the same thing is happening here at overdrive, just the opposite of starting out!
So what does all this mean? If you run a taller gear ratio, and you have good engine power to begin with your belt will be lower in the primary and higher in the secondary clutch at wide open, the sled will go faster from less frictional loss, but what gear ratio you can run and still maintain optimum efficiency will only be found thru testing!! Try a 24 top, see what happens, is it faster from point a to b? are the clutch's cooler running? are the engine rpm's the correct range? then do it with 25. You have to keep notes and then when your all done, its very simple to calcualte the data and make the appropriate choice as to what to use for a given race distance or speed requirement, the guy with the best tuning notes wins!!
Here is a formula to play with, but you still need to test, this is just a tool to use:
Shift ratio= engine speed(rpm) x drive sprocket pitch diameter = (? ), divided by,
mph x gearing x 336
Last edited:
nhsrx701
New member
- Joined
- Jan 27, 2005
- Messages
- 119
That is an awsome post Mrviper...Rock On!
deekersrx700
New member
Excellent post mr viper, I kind of wish I hadn't geared down today after reading that, but I have to test and see what my results are, by gearing down to 22/39 from 23/38 how much affect on my rpm will that have?
mulderdad
New member
Wow!
That's why I read All your posts mrviper.
Great info.
mul
That's why I read All your posts mrviper.
Great info.
mul
ok, to answer some pm questions all at once.
When your picking your gearing your also setting up the sled for a given distance and purpose!!! Meaning you cant run tall gears effectively in short runs, thats not what I was trying to explain. Deek is worried about 2000ft radar runs, he wants max top speed in 2000ft. The only way to get that is with the most amount of efficiency you can get thru the clutch's and driveline. This does apply to about all other riding except short 500-660 ft runs.
1.)steeper gears take load off the engine, you can run more weight in the clutch because the motor isnt working as hard to pull the load! If you have a torq engine that likes to be shifted hard then you know which way youd want to go.
2.) taller gears load the engine harder and keep more load on it thru out its range.
3.) you still have to have the correct combination of weights,springs and helix choice to make the whole package work together!
4.) your rear secondary spring twist can yield large increases in speed and efficiency, test with it at differnt twist and you will see!!! Alot of times guys never change this and they have no idea at the increases in speed they have right before thier eyes. It doesnt stay the same for any condiiton you ride the sled in. Wet, heavy snow will require more tension. Nice lake running powder type or hard pack groomed trails require less tension. TEST!! TEST!! TEST!!!
5.) Turk, myself and alot of others on here can give you a clutch set up and gearing idea, but you need to test YOUR sled, with YOU on it, and in the conditions that YOU will be running in, its never gonna be a bolt in and be 100% perfect set up, theres always very fine tuning to do to make it perfect for you and your sled, they are not all the same by a long shot!
When your picking your gearing your also setting up the sled for a given distance and purpose!!! Meaning you cant run tall gears effectively in short runs, thats not what I was trying to explain. Deek is worried about 2000ft radar runs, he wants max top speed in 2000ft. The only way to get that is with the most amount of efficiency you can get thru the clutch's and driveline. This does apply to about all other riding except short 500-660 ft runs.
1.)steeper gears take load off the engine, you can run more weight in the clutch because the motor isnt working as hard to pull the load! If you have a torq engine that likes to be shifted hard then you know which way youd want to go.
2.) taller gears load the engine harder and keep more load on it thru out its range.
3.) you still have to have the correct combination of weights,springs and helix choice to make the whole package work together!
4.) your rear secondary spring twist can yield large increases in speed and efficiency, test with it at differnt twist and you will see!!! Alot of times guys never change this and they have no idea at the increases in speed they have right before thier eyes. It doesnt stay the same for any condiiton you ride the sled in. Wet, heavy snow will require more tension. Nice lake running powder type or hard pack groomed trails require less tension. TEST!! TEST!! TEST!!!
5.) Turk, myself and alot of others on here can give you a clutch set up and gearing idea, but you need to test YOUR sled, with YOU on it, and in the conditions that YOU will be running in, its never gonna be a bolt in and be 100% perfect set up, theres always very fine tuning to do to make it perfect for you and your sled, they are not all the same by a long shot!
Last edited:
vipertripplexxx
New member
Speed trick... Gear up one tooth on top gear 24. Pull the bolts that hold the secondary apart, three bolts on back of clutch, and leave them out. Now the secondary can fully close, and the belt should ride up out of the sheave slightly. Set the belt deflection by moving the motor/clutch center to center closer together, usually about 1/8" to 1/4" closer. This will give you back the holeshot, as the clutches are now giving more reduction from the start, with increased top speed of the 24 tooth gear. you will may need to tune for proper rpm's.