850/800 secondary clutch offset

TRS · Jan 23, 2019

We are finding to many variables in clutch alignment tools to get an accurate or a proper base setting for our mountain sleds.
There are major variations regarding the factory set lead in. Most of these variables cannot be adjusted out to get within the factory spec. regardless if it’s a 800 or 850 chassis.
We use an SLP bar to set our base measurements, and sadly they are no longer available. Belt life is what we strive for and is very relative to offset.
What we have found for an offset measurement, that enhances belt life on our clutch setups, doesn’t mirror the factory recommendation.
There is an easy method to accomplish offset. You will need a piece of 1/4” key stock, digital caliper, and jackshaft spacers along with float washers. Spacers and washers are available from your Polaris dealer.
Remove your belt and bridge the key stock across the backside of your primary. With your caliper measure from the key stock to the outside leading edge of your secondary. The measurement we have found that works is:
850. 2.57”
800. 2.60”
You will find most sleds will need around .100” added to the shim stack.
Once you get it shimmed to this spec you can adjust float. We float the secondary outward .015-.030”. Over float causes undue belt wear. Carbon fiber belts start to stress, somewhat, around .030” of misalignment.
These measurements have been working very well for us. You can fine tune your offset, in or out, by learning how to read your witness marks on your belt. Each sled and riders belt wear pattern will be a little different in this respect. Gearing, motor mount wear, NA, turbo and other factors contribute.
I wish you all the best in belt retention.

EDIT: Thanks Tewstroke
This is for a non-ES clutch. Adjust your measurement accordingly.
Remove after market torque arms when using this method.

PaulAnd · Jan 23, 2019

TRS said:
We are finding to many variables in clutch alignment tools to get an accurate or a proper base setting for our mountain sleds.
There are major variations regarding the factory set lead in. Most of these variables cannot be adjusted out to get within the factory spec. regardless if it’s a 800 or 850 chassis.
We use an SLP bar to set our base measurements, and sadly they are no longer available. Belt life is what we strive for and is very relative to offset.
What we have found for an offset measurement, that enhances belt life on our clutch setups, doesn’t mirror the factory recommendation.
There is an easy method to accomplish offset. You will need a piece of 1/4” key stock, digital caliper, and jackshaft spacers along with float washers. Spacers and washers are available from your Polaris dealer.
Remove your belt and bridge the key stock across the backside of your primary. With your caliper measure from the key stock to the outside leading edge of your secondary. The measurement we have found that works is:
850. 2.57”
800. 2.60”
You will find most sleds will need around .100” added to the shim stack.
Once you get it shimmed to this spec you can adjust float. We float the secondary outward .015-.030”. Over float causes undue belt wear. Carbon fiber belts start to stress, somewhat, around .030” of misalignment.
These measurements have been working very well for us. You can fine tune your offset, in or out, by learning how to read your witness marks on your belt. Each sled and riders belt wear pattern will be a little different in this respect. Gearing, motor mount wear, NA, turbo and other factors contribute.
I wish you all the best in belt retention.

Thanks for sharing!
Great info!

Sent from my iPhone using Tapatalk

gtwitch · Jan 23, 2019

Thanks Tony!!! Best and easiest method I have seen and I will use it now in my shop. Printed it and have it hanging on the end of the tool box.
gtwitch in wyoming

Tewstroke · Jan 24, 2019

Thanks again Tony!

I have elec. start, so I’ve used the 191 bar and followed your prior instructions using a non-ES clutch for alignment only and then switched back.

The measurements given by this method are using a standard, non-ES clutch ,correct?
To use this caliper method with an electric start clutch, one would have to add the width of the starter ring gear, right? Or, put on a regular clutch for alignment , if available.

TRS · Jan 24, 2019

Tewstroke said:
Thanks again Tony!

I have elec. start, so I’ve used the 191 bar and followed your prior instructions using a non-ES clutch for alignment only and then switched back.

The measurements given by this method are using a standard, non-ES clutch ,correct?
We would have to add the installed width of the starter ring gear to use this newer caliper method, correct?

Yes, you are correct. Thank you
The other issue, aftermarket torque arms. I recommend removing them.

indydan · Jan 24, 2019

TRS said:
The other issue, aftermarket torque arms. I recommend removing them.

Ditto....... I DO NOT LIKE AFTERMARKET TORQUE ARMS UNLESS ITS A DRAG RACE ONLY SLED.

Dan

carbontj · Jan 24, 2019

I don't usually post much on here, but I am knee deep in this topic on the RZR..I am old school being I have been in the industry since 1974...Let me explain how I see it done proper...there are 2 fixed sheaves, one on each clutch, fixed sheaves are static and do not move, thats what you need to measure to and from...this is how I see the proper way to measure offset..Take the secondary apart..Use only the fixed sheave and slide it back on the jackshaft. On inside of that fixed sheave take a bar, (see below how thick) 4-6' longer than your center distance, and hold it on flush on the inside, rotate it down to the Primary clutch FIXED sheave. When you just graze the inside (bottom) of the fixed primary sheave with your correct thickness bar, you will be correct offset...(or with clutches assembled or together, you can put the correct thickness bar between the 2 secondary sheaves, little harder to do maybe but works the same)...Now if your belt is 1.420 like most new belts, divide that by 2 or half, you get .710. make a bar or add to your stock bar (.625 thick add .085) or make it .710 thick, this will be your offset so when you are full shift your belt will be on center...it is old school but is one way to find the offset of the clutches.. for sure not as easy as a offset bought bar, just old school version...might be somewhat confusing as no one does it that way anymore other than old school racers like me...or call me with any questions..TJ Patrick

TRS · Jan 24, 2019

carbontj said:
I don't usually post much on here, but I am knee deep in this topic on the RZR..I am old school being I have been in the industry since 1974...Let me explain how I see it done proper...there are 2 fixed sheaves, one on each clutch, fixed sheaves are static and do not move, thats what you need to measure to and from...this is how I see the proper way to measure offset..Take the secondary apart..Use only the fixed sheave and slide it back on the jackshaft. On inside of that fixed sheave take a bar, (see below how thick) 4-6' longer than your center distance, and hold it on flush on the inside, rotate it down to the Primary clutch FIXED sheave. When you just graze the inside (bottom) of the fixed primary sheave with your correct thickness bar, you will be correct offset...(or with clutches assembled or together, you can put the correct thickness bar between the 2 secondary sheaves, little harder to do maybe but works the same)...Now if your belt is 1.420 like most new belts, divide that by 2 or half, you get .710. make a bar or add to your stock bar (.625 thick add .085) or make it .710 thick, this will be your offset so when you are full shift your belt will be on center...it is old school but is one way to find the offset of the clutches.. for sure not as easy as a offset bought bar, just old school version...might be somewhat confusing as no one does it that way anymore other than old school racers like me...or call me with any questions..TJ Patrick

TJ,
I have to respectfully disagree, but we are still using fixed sheave measurements. A RZR engine and transmission are fixed. I do my share of work on them also. They have their own alignment issues that can be remedied using SDI bars then adjusting offset. My personal RZR 1000 center to center was off north of .100”.
What the old school way doesn’t account for on our mountain sleds, is poor lead in and the amount engines are moving in the chassis under load. Motor mount issues and lack of engine alignment adjustments contribute to excessive belt wear.
The old school way considers only a static non loaded CVT system as in the RZR. The PRO chassis gave us the ability to adjust center to center and lead in if you had the knowledge. You could then add torque arms to keep it in a more static condition.
The measurements I have posted have given us the best belt life taking engine and drive train movement into consideration. I can’t say if this will work on flatland sleds, they spend more time in an unloaded state.

Nitroused383 · Jan 24, 2019

Thanks for the write up. Can you confirm if your measurement is to the outside of the keystock or if you are measuring to the surface similar to using a depth mic?

TRS · Jan 24, 2019

Nitroused383 said:
Thanks for the write up. Can you confirm if your measurement is to the outside of the keystock or if you are measuring to the surface similar to using a depth mic?

The same plane as the back of the clutch. Yes, as you were using a depth mic.

Tewstroke · Jan 24, 2019

I'll just keep changing the inserts each year then.
Who has the best price?

Is there any advantage with using PTO inserts on the mag side as well?

Also, did Northstar Rick offer harder durometer motor mount rubbers?

Tewstroke · Jan 24, 2019

I went and got some keystock during lunch.

I'm going to see how close I got using the 191 bar for the first time!

carbontj · Jan 24, 2019

TRS, you are correct the RZR is Offset north over .100 to .150!!!, the center distance I have remedied that issue with what we are doing...We have build in lead to the primary for torque as we have with snowmobiles....In my discussions with Polaris engineering they have a formula that I don't understand, maybe because I am not a certified engineer...But to me math is math...If a belt is 1.420 and half that is .710...if you make that the offset between the 2 fixed sheaves, that will allow the other .710 to be divided between both sides of the clutches..done not that way for many years on snowmobile race sleds.. It is in many older manuals as well..What ever works for everyone is what works, more than one way to skin a cat..I was explaining one way to do it...

The RZR clutching is another topic!!! I am knee, elbows, legs deep in that clutch...we hope to resolve the overheating issues...

tdbaugha · Jan 24, 2019

carbontj said:
this will be your offset so when you are full shift your belt will be on center...it is old school but is one way to find the offset of the clutches..

Mountain sleds are rarely at full shift.

TRS said:
You can fine tune your offset, in or out, by learning how to read your witness marks on your belt. Each sled and riders belt wear pattern will be a little different in this respect. Gearing, motor mount wear, NA, turbo and other factors contribute.

The witness marks seem to match up the best when both the fixed and moveable sheave are similar in temperature from what I have found also. Every box stock Polaris sled I have seen and/or helped with clutching recommendation has the fixed sheave significantly hotter than the moveable. Once the secondary comes out, they even out.

Tewstroke · Jan 25, 2019

Tony,
When you say to read the witness marks “on your belt” , do you mean the marks that the belt makes on the primary clutch faces? In other words, learn to read the witness marks left by the belt ( whether they are similar in height/position on both faces of the primary clutch.) That’s what I thought tdbaugha was showing in his early photos.
I just want to be sure that I didn’t misunderstand the concept.

BTW, the caliper method gave me the same measurement as doing it with the 191 bar.
You are an accurate/precise dude!!

Tewstroke

tdbaugha · Jan 25, 2019

These are the belt witness marks. They should be the same on both sides of the belt.

Tewstroke · Jan 25, 2019

Thank so much for sharing!
I had misunderstood what you meant.

Knowledge is power, now it will mean more power to the track! LOL

sled_guy · Jan 25, 2019

How about posting up a picture of the key stock laying in place so we can see its orientation to both clutches?

Thanks,
sled_guy

TRS · Jan 25, 2019

sled_guy said:
How about posting up a picture of the key stock laying in place so we can see its orientation to both clutches?

Thanks,
sled_guy

I’ll give it a try. I’ll take the oil tank and guard off. Take a pic from the top so there is no question about orientation.

Tewstroke · Jan 25, 2019

Tony,

Thanks for taking the time to explain and illustrate the caliper method for setting secondary clutch offset.

The 1/4" bar stock works great. I also placed a metal ruler across the outside face of the secondary to be able to measure easily between it and the bar stock.

.. Can't wait to try it out tomorrow and see where the witness marks end up.

850/800 secondary clutch offset

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