Clutch balance after shimming for belt clearance ?

[overboard]

Hi. SLP Stage 3 with MTX weights - I took the clutch, minus cover and spring to dealer (could not get the thing apart without special tool). They shimmed it to the correct width with a broken in belt.
So I started thinking, the spider dictates where the cover orients (line up the arrows), but if the spider is now off by 120 or 240 degrees, the cover will also end up out by that much.
Are the sheaves balanced separately from the cover then assembled, or is the entire clutch assembled and adjustments made to both cover and sheave (at factory - I know a balance is done on a full clutch).
Where I'm going with this is questioning whether I need to re-balance my clutch. I know the manual says the spider makes only a small difference in balance, but is it critical that the cover matches to the alignment with the sheaves ? I did not mark this so if it is a relevant factor, I guess I'll need a balance & if so, who does balancing in Calgary AB area ?
I'm going to read the manual again to see if I'm missing something obvious.
Thx.

 

[DLynn]

Clutch's are production balanced at the factory when they are new. This means they can be very close to not so close. In our shop we go beyond what would be called acceptable by the factory. The closer you get to zero the better off you are. Just like a set of tires, as a clutch gets a little wear or any type of change is made such as new weights, spring or especially changing the spider location has a big effect on the overall balance. We commonly find clutch weights to have large variation between each other. I have seen as much as 8/10th of a gram on weights that are marked the same. This will cause major issues when balancing.
When balancing any item that has moving parts, it has a big effect on the overall balance when things move or change. This is an uncontrollable condition on balancing a clutch that is in constant motion.
In my opinion if you make major changes to your clutch it should be re-balanced. Also it would be a good idea to have it serviced and balance checked every other season. Again my opinion. An out of balance clutch is working hard to destroy your crank and crank seal. It will win sooner or later.
Clutch’s are a item that require occasional service.
By the way....Merry Christmas

 

[Bossman]

Clutch balancing

If the shop marked the relationship between the fixed sheave and moveable sheave before disassembly and selected shims that brought that relationship back to+or-.75 inch when done, the clutch balance will be within tolerance. This accomplished by moving the spider counter clockwise 1/3 or 2/3 turn from its original position in the moveable sheave. The X on the spider no longer aligns with the X on the moveable sheave or cover. The spider is a high quality casting that is consistent it weight and therefore balance. Also, most of its mass close to the center post so a change in balance is very unlikely.

 

[TRS]

If the shop marked the relationship between the fixed sheave and moveable sheave before disassembly and selected shims that brought that relationship back to+or-.75 inch when done, the clutch balance will be within tolerance. This accomplished by moving the spider counter clockwise 1/3 or 2/3 turn from its original position in the moveable sheave. The X on the spider no longer aligns with the X on the moveable sheave or cover. The spider is a high quality casting that is consistent it weight and therefore balance. Also, most of its mass close to the center post so a change in balance is very unlikely.

Yes, this is in accordance with Polaris spec. for belt sheave clearance adjustment.

DLynn,
You are correct in what we see from the factory. Many times we have disassembled new clutches and the spiders are loose, not torqued. This provides the consumer with an unbalanced clutch off the shelf or when properly torqued. These need to be rebalanced or replaced. Production weights need to be matched, your findings here are consistent with what we have found also with many aftermarket weights. These big twins destroy primary clutches with a lot of internal wear, and the lack of maintenance, causing a definite imbalance.

 

[Daggerboat]

Do NOT get a clutch balanced at Specialty Sleds in Edmonton.I bought a brand new clutch thru them and paid extra to have them balance it. Luckily I marked both sheaves before I installed it because after the first ride I could see the spider had turned and my marks were now 2" apart.... So $800 later I still don't know if the clutch is properly balanced.

 

[DLynn]

Do NOT get a clutch balanced at Specialty Sleds in Edmonton.I bought a brand new clutch thru them and paid extra to have them balance it. Luckily I marked both sheaves before I installed it because after the first ride I could see the spider had turned and my marks were now 2" apart.... So $800 later I still don't know if the clutch is properly balanced.

I would give them a call, sounds like someone just made a mistake. If the spider has moved then it's not tight along with the lock nut. You have some issues that need some attention. Good Luck!!

 

[overboard]

Thank you all

 

[Merlin]

Hi. SLP Stage 3 with MTX weights - I took the clutch, minus cover and spring to dealer (could not get the thing apart without special tool). They shimmed it to the correct width with a broken in belt.
So I started thinking, the spider dictates where the cover orients (line up the arrows), but if the spider is now off by 120 or 240 degrees, the cover will also end up out by that much.
Are the sheaves balanced separately from the cover then assembled, or is the entire clutch assembled and adjustments made to both cover and sheave (at factory - I know a balance is done on a full clutch).
Where I'm going with this is questioning whether I need to re-balance my clutch. I know the manual says the spider makes only a small difference in balance, but is it critical that the cover matches to the alignment with the sheaves ? I did not mark this so if it is a relevant factor, I guess I'll need a balance & if so, who does balancing in Calgary AB area ?
I'm going to read the manual again to see if I'm missing something obvious.
Thx.

I used Bel Engine Services in Edmonton & dealt with Les(1 - 780 - 465 - 3586).

As a bit of preventative maintenance last year I checked my low mileage clutch(just under 800 miles) & found .035" belt clearance & .006" button to tower clearance. Thanks to spot-on blueprinting from the factory!

Suffice it to say that after I'd re-adjusted the belt clearance the, orientation of the sheave halves had changed enough to warrant balancing.

Apparently the clutch assy. had an initial imbalance of 3.8 grams & was tuned down to .1 gram

Once again, I used them for the balancing only, not the rebuilding.

 

[rydningen]

I recently had a clutch balanced, it was made up of parts from different clutches, they got it down from 25g to 3,5g. I asked if this still wasnt alot of imbalance, but they assured me that it was not.

Any opinions on this, are they way off?

Sorry for the OT in relation to original post.

 

[DLynn]

I recently had a clutch balanced, it was made up of parts from different clutches, they got it down from 25g to 3,5g. I asked if this still wasnt alot of imbalance, but they assured me that it was not.

Any opinions on this, are they way off?

Sorry for the OT in relation to original post.

That is a lot of unbalance for a Polaris clutch to start with. 3.5g is still a ways out. However for production balancing that's not un-heard of. We us the ISO 6.3 quality grade for our start point when balancing motorsport clutch's. On average using that standard it would be acceptable to leave as much as +/- 1 gram of unbalance on each plane of the clutch. We go beyond that and in most cases can hit below 3/10th of a gram. Again there are a lot of variables to getting a clutch that close.
Any time you have multiple parts, parts that can change position, parts with wear bushings, parts that are not identical weight all bolted together you have created a balancing nightmare. We commonly see fly weights that are a .5 to .8 grams different. This would cause huge unbalance if not corrected prior to balancing the clutch. Then add a worn bushing. Add .004" of wear and the balance will be all over the place and change every time that part moves.
I guess were this all ends up is have your clutch's balance every couple years and the parts checked for wear and ride you sled. As long as you having it done by a shop that normally does motorsport clutch's you should be just fine.

 

[geo]

How do you balance the clutches D-Lynn. Do you leave the weights in? Is the clutch opened or closed? What rpm? Do you do the secondary too? Machine you use?

The reason I ask is it is like "black magic" around here with a couple of machine shops set-up with a taper or two. But, they have different methods and rpm?

I have a simple static balancer (built it myself many moons ago and it is a quality piece). I use it on my bike tires and it works. I balanced my twin squirrel cage fan on my fireplace insert (.8 gr on side and .6 on the other motor) and it made it a lot quieter lol.
I've checked some of my clutches in the past and found them to be out statically but decided to not screw with them because of a bad experience sending some TRA's out and the questions of at what point of shift and what about harmonics at "x" rpm come to mind. lol.

Do you think balancing your clutches out statically does any good? Or harm lol.

 

[TRS]

How do you balance the clutches D-Lynn. Do you leave the weights in? Is the clutch opened or closed? What rpm? Do you do the secondary too? Machine you use?

The reason I ask is it is like "black magic" around here with a couple of machine shops set-up with a taper or two. But, they have different methods and rpm?

I have a simple static balancer (built it myself many moons ago and it is a quality piece). I use it on my bike tires and it works. I balanced my twin squirrel cage fan on my fireplace insert (.8 gr on side and .6 on the other motor) and it made it a lot quieter lol.
I've checked some of my clutches in the past and found them to be out statically but decided to not screw with them because of a bad experience sending some TRA's out and the questions of at what point of shift and what about harmonics at "x" rpm come to mind. lol.

Do you think balancing your clutches out statically does any good? Or harm lol.

Us old guys remember in the '70s when Arctic sold you a Z race sled you got a great static balancer for your clutch. I know where there are a few yet today.

 

[geo]

Unfortunately I stayed away from winter back them (racing in the south) lol.

Any pics TRS? I like building tools more than sleds lol. Im sure our local crank guy has a couple of Poo PTO ends kicking around as paper weights lol.

 

[DLynn]

How do you balance the clutches D-Lynn. Do you leave the weights in? Is the clutch opened or closed? What rpm? Do you do the secondary too? Machine you use?

The reason I ask is it is like "black magic" around here with a couple of machine shops set-up with a taper or two. But, they have different methods and rpm?

I have a simple static balancer (built it myself many moons ago and it is a quality piece). I use it on my bike tires and it works. I balanced my twin squirrel cage fan on my fireplace insert (.8 gr on side and .6 on the other motor) and it made it a lot quieter lol.
I've checked some of my clutches in the past and found them to be out statically but decided to not screw with them because of a bad experience sending some TRA's out and the questions of at what point of shift and what about harmonics at "x" rpm come to mind. lol.

Do you think balancing your clutches out statically does any good? Or harm lol.

Ok....First off I prefer to balance with all the parts you are going to run. Some other shops may do it different. I do have several race teams that change springs and weights several times a day. The process for them is different than for most clutch's. First scale the fly weights and make sure they are spot on to each other. Index the spring base on the spider.
We spin the clutch's at 1500 RPM however there is a calculation that is factored in by the program that simulates 8000 RPM. We mount the clutch on a mandrel that has the exact taper as a crank shaft and we use a Polaris factory bolt or what ever clutch we are balancing to hold it on the taper.
We have a Balance Master HB-75 Dual Plane balancer that runs Easy Balance 2.2 software. It was purchased in 2011 and was a new unit.
As for secondary clutch's we do balance them also. I would guess we do 10 to 1 primary vs secondary's. I guess anything a person can do to help balance there clutch's is better than nothing. However with the cost of a new motor it best (in my opinion) to get the best balance possible.
After you purchase the balance machine for 24,000.00 and have mandrels built at 500.00 each for each different manufacture and buy a lathe to adjust belt to sheave clearance and a machine to clean the clutch's and several thousand dollars worth of hand tools you too can balance clutch's. Although I have seen very large propellers done on a static balancer and it seemed to work just fine. The prop will only turning 80 to 120 RPM.

 

[TRS]

Ok....First off I prefer to balance with all the parts you are going to run. Some other shops may do it different. I do have several race teams that change springs and weights several times a day. The process for them is different than for most clutch's. First scale the fly weights and make sure they are spot on to each other. Index the spring base on the spider.
We spin the clutch's at 1500 RPM however there is a calculation that is factored in by the program that simulates 8000 RPM. We mount the clutch on a mandrel that has the exact taper as a crank shaft and we use a Polaris factory bolt or what ever clutch we are balancing to hold it on the taper.
We have a Balance Master HB-75 Dual Plane balancer that runs Easy Balance 2.2 software. It was purchased in 2011 and was a new unit.
As for secondary clutch's we do balance them also. I would guess we do 10 to 1 primary vs secondary's. I guess anything a person can do to help balance there clutch's is better than nothing. However with the cost of a new motor it best (in my opinion) to get the best balance possible.
After you purchase the balance machine for 24,000.00 and have mandrels built at 500.00 each for each different manufacture and buy a lathe to adjust belt to sheave clearance and a machine to clean the clutch's and several thousand dollars worth of hand tools you too can balance clutch's. Although I have seen very large propellers done on a static balancer and it seemed to work just fine. The prop will only turning 80 to 120 RPM.

Nice, very nice. Wish I had one.

 

[TRS]

Unfortunately I stayed away from winter back them (racing in the south) lol.

Any pics TRS? I like building tools more than sleds lol. Im sure our local crank guy has a couple of Poo PTO ends kicking around as paper weights lol.

I will look for a picture in my archived files.

 

[Kraven]

I used Bel Engine Services in Edmonton & dealt with Les(1 - 780 - 465 - 3586).

As a bit of preventative maintenance last year I checked my low mileage clutch(just under 800 miles) & found .035" belt clearance & .006" button to tower clearance. Thanks to spot-on blueprinting from the factory!

Suffice it to say that after I'd re-adjusted the belt clearance the, orientation of the sheave halves had changed enough to warrant balancing.

Apparently the clutch assy. had an initial imbalance of 3.8 grams & was tuned down to .1 gram

Once again, I used them for the balancing only, not the rebuilding.

On the bold, @ .035" belt to sheave clearance from the factory, that's one of the better ones by far!

Most I've seen are around .070" from the factory

A lot of performance left on the table there, wish more sledders would take the time to check/correct these issues

 

[TRS]

Unfortunately I stayed away from winter back them (racing in the south) lol.

Any pics TRS? I like building tools more than sleds lol. Im sure our local crank guy has a couple of Poo PTO ends kicking around as paper weights lol.

Here it is

 

[m8magicandmystery]

I balanced my twin squirrel cage fan on my fireplace insert .

and keep them vacuumed and brushed for lint/hairballs that collect on the vanes..

 

[geo]

and keep them vacuumed and brushed for lint/hairballs that collect on the vanes..

You got wolf-based dogs too eh, lol.

Thanx TRS. That looks "robust" lol. They didn't order as much from China back then eh.

4Z. What's your turn around time? Prices (if it is allowed)? Do you true the sheave faces as well?