Checking primary finish spring load

[Brock]

Spring pocket on spider

measurement difference from spring pocket on spider

Spring pocket on clutch cover.

Measurement difference from spring pocket on clutch cover.

Add these both together and its the final load for spring. This clutch was machined and indexed . The total is 1.281" load now. Add some glide washers to get 1.25 " load and all good.
I like the 1.25" load vs the polaris 1.19" load anyways.
Just some information

 

[Brock]

Bump

Guy's, I've been measuring quite a few from factory just stock and the finish spring load is different on everyone.

Polaris state's a 1.19" finish primary spring load in the specs. I've had 1.25, 1.28,1.29,1.30, 1.31.......etc......

This effects the finish spring rate up top on rpm. Could be 50, 100 or more rpm loss up top with the spring being wimped out too. This would have an affect of low rpm out in the field and could get worse while spring binds,gets hot,belt heat etc....

This is something to look at.

I'll give u an example..
A Polaris spring is a 120/310
Now that's the 2.5" and 1.19" loads on the spec that Polaris has given for years.

Now you take that same spring, install it in a clutch that I just measured with a 2.58" and a 1.31" loads. That changes the 120/310 to about a 115/290.
This is a big deal that's getting overlooked.
This can be measured at a machine shop,or do it yourself.
They do make glide washers to help this get closer to a 1.25" finish load were it should be. Glide washers are about 0.040" thick.

This may be the cause of some low rpm sleds.

 

[Jayxcr]

This is something I've never checked but I will from now on!! I recently put on a Patrick carbon fiber cover and it changed how the sled ran. The rpm's actually went up but sled slowed down. Wouldn't fully shift out. Turns out it had a much tighter squish on the spring than stock cover, ended up taking 2 glide washers out and bingo, back to where I was. This check would have saved a lot of frustration!
Thx Brock!

 

[Brock]

No problem Jay.

I'm putting this out there because every primary I measured is a little different.

This is a big deal. And it gets so easily overlooked

 

[racerdave]

I understand load and the Polaris spec numbers at where they are measured. I don't understand from your pics and where you have your dial indicator getting these measurements. One shows the indicator zeroed in the spider pocket. Ok, that is a base measurment. Then your .539 from sitting on the tower with the clutch in a closed state. I don't understand what that shows? Then a zeroed indicator in the face cover pocket upside down on the spider. Again showing what? Finally the .742 from the indicator moved out to the cover edge with it again sitting on the spider. Huh? What am I missing here? Why not with the clutch bolted together with no spring. Held open and a snap gauge then used to measure the distance inside between the spider cup and face cup. Now this way I can understand getting the base open clutch spring load, Now set up a indicator jig, and zero it on the outside of the face plate. Drop the clutch open, measure that travel and then subtract that from your first measurement between the cups for your final load measurment. Here i can see your 1.281 measurement. Again, if I am wrong explain to me why, from your pics above and where/why you are taking measurements? Feliz Navidad

 

[Brock]

I posted those pics as a generalisation to were you should measure and the easiest way to take a pic.
Sorry I'm confusing you.


Were the clutch cover bolts to clutch tower, you measure from this point to machined spring pocket

On clutch sitting down as shown. This duplicates full shift out. Measure from were clutch cover meets clutch tower bolts to spring pocket inside spider.

If you have the clutch together, it's to hard to measure as spider is in the way when in full shift out.

Are you understanding now??

 

[racerdave]

Seems to me like a harder more involved proccess. Go back to my above and reread what I underlined.Plenty of room to get a snap gauge into a open clutch bolted together with no spring. Explain to me why my above way won't give the correct number with less work?

 

[Brock]

It doesn't matter how you measure as long as it's correct.

I think it's easier with everything apart,just me.

I'm just trying to help.

 

[Brock]

I'll tell u why I don't use a snap gauge as u suggested. You have to wiggle it out and it's hard too. After that, how accurate is it??
Now, on top of that, ur using another measuring device against another that u just wiggled out. Now how accurate is that??

Plus I like to take apart because all clutch cover machined spring pockets have varied from 0.700" to 0.760" as the one picture.

To me taking apart is the only accurate way.

Your way will work, but what's the actual spring cup measurement on the clutch cover as shown. Your way won't tell this.

I'm not arguing with you rd. Your way will work too. Me, myself personally, I like to take it all apart and measure since I'm doing work to them anyway.