Polar Air Gap Problem

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Polar Air Gap Problem

Postby dragnflyjd » Mon Jul 24, 2017 10:45 pm

Just want to check if I have an issue here or not. Still new to this Junior game after years in the big cars. I have Polar clutch that we are preparing for the season ahead here in Aus. After some advice on here i decided to buy some new ramps and new purple spring for the primary. Also after some reading on here i decided to check the 'air gap'.
So with the clutch OFF the car i have 100 thou clearance which is obviously too much. But here's what confusing me. When the clutch is ON the car or being pushed together on the bench (rather strongly), the gap shrinks to virtually no gap at all.
Is this right?
I've noticed the ramps hit the inside of the movable sheave, and the distance that is taken away from when its done up on the car, comes from a gap between the outer cover and post. Once compressed it pushed the ramps onto the sheave under the pressure of the spring and consequently closes my air gap. I'm also running a normal brand new 780 wide terminator belt.
Ive included some pics of my old ramps (15/30/24) to show wear marks (if helpful) and a pic of the post with a marker showing where the clutch sits when off the car. You can also see the marks left from the ramps hitting on the inside on another pic also.
Hope this makes sense and any help would be great.

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Re: Polar Air Gap Problem

Postby tanners » Tue Jul 25, 2017 4:53 pm

You should measure the air gap for the belt while holding the movable sheave as tightly toward the fixed sheave as you can by hand. It is normal for the movable sheave to have freeplay when the clutch is assembled. If your ramps are hitting the movable sheave, you have a clearance issue.
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Re: Polar Air Gap Problem

Postby dragnflyjd » Tue Jul 25, 2017 8:12 pm

Thanks tanners. Ok so its normal to have your air gap close up once back on the car with the bolt done up?
So if I've got 100 thou gap with no shims that means i need a bigger belt yeah?
If the ramps are hitting which they definitely are, how do you fix this?
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Re: Polar Air Gap Problem

Postby drags3078 » Wed Jul 26, 2017 4:21 pm

You need to verify Belt Air Gap , like Tanners mentioned you have to hold pressure on the Moveable shieve then measure clearance between belt and Clutch with a Feeler Gage , I would shoot for .035 belt air gap with new belt ..... the Moveable shieve is always a little loose until fired up and then the centrifugal weights make the roller hit the ramp
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Re: Polar Air Gap Problem

Postby dragnflyjd » Wed Jul 26, 2017 5:06 pm

OK the belt air gap is defiantly 100 thou with the clutch held tightly while off the car.
If I put it on the ground and press down with my body weight, the 100 thou disappears completely. (this is the same as if its bolted onto the car)
The 'gap' is taken up by the polar cover to spring retainer/post area. That in turn pushes the ramps into the back of the movable sheeve, closing the 100 thou clearance i had, to Zero.
The movable sheeve is not loose at all. I fact its under slight pressure from the primary spring. I thought i may be onto something with the post being machined down, but looked a friends primary post last night and its the same.
It measures 3.1".
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Re: Polar Air Gap Problem

Postby tanners » Thu Jul 27, 2017 9:01 am

There should be no interference between the ramps and the movable sheave. The one non-overdrive polar that I had was clearanced at the ramp locations so that they did not touch. When you hold the movable closed to measure, don't use excessive pressure. Just use enough force to take out all of the slack.
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Re: Polar Air Gap Problem

Postby drags3078 » Thu Jul 27, 2017 10:54 am

dragnflyjd wrote:OK the belt air gap is defiantly 100 thou with the clutch held tightly while off the car.
If I put it on the ground and press down with my body weight, the 100 thou disappears completely. (this is the same as if its bolted onto the car)
The 'gap' is taken up by the polar cover to spring retainer/post area. That in turn pushes the ramps into the back of the movable sheeve, closing the 100 thou clearance i had, to Zero.
The movable sheeve is not loose at all. I fact its under slight pressure from the primary spring. I thought i may be onto something with the post being machined down, but looked a friends primary post last night and its the same.
It measures 3.1".



The Cover should not touch the spring retainer when bolted to the engine , if it does then you have a problem with components that don't match each other
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Re: Polar Air Gap Problem

Postby dragnflyjd » Sat Jul 29, 2017 4:32 am

OK the cover doesn't hit the spring retainer.(Probably didnt explain that too well)
I keep coming back to the post maybe short. Come someone confirm the length of a polar post?
If I shim the post up with up a thick washer (110" odd), the ramps no longer contact the movable sheeve and it actually has little freeplay on the post. (like what tanners said it should have)
Could someone also confirm the wear marks on the ramps look right as I know shimming the cover will change how they sit/perform as well.
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Re: Polar Air Gap Problem

Postby drags3078 » Thu Aug 03, 2017 10:07 am

I like the roller .015 to .025 from apply angle of the ramp
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Re: Polar Air Gap Problem

Postby dragnflyjd » Mon Aug 07, 2017 1:37 am

Here's a couple of videos to better explain what's going on.
https://youtu.be/tlv3FzU033M
https://youtu.be/jLhnc15m07Y
The post sticks up100 thou from the spring retainer and there's a 200 thou deep recess in the cover.
When I'm pressing down in the first clip it's the pressing the cover down on the post
Any help would be great as I can't seem to get to the bottom of what the issue is???
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Re: Polar Air Gap Problem

Postby Drewst556 » Mon Aug 20, 2018 11:41 am

I know this is from a year ago but did you ever get your problem fixed ? I had a similar issue the ramps hitting the movable sheave would close up the air gap when installed on car now that I fixed that problem I have to much air gap and need a wider belt. Was curious if you found your problem ?
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Re: Polar Air Gap Problem

Postby dragnflyjd » Tue Aug 21, 2018 7:09 pm

Hi Drewst556, no never got this sorted. Ended up selling the clutch and moving to a Craws ZR3 with a Shockwave and haven't looked back.
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Re: Polar Air Gap Problem

Postby slowgoat » Tue Aug 21, 2018 11:12 pm

Drewst556 wrote:I know this is from a year ago but did you ever get your problem fixed ? I had a similar issue the ramps hitting the movable sheave would close up the air gap when installed on car now that I fixed that problem I have to much air gap and need a wider belt. Was curious if you found your problem ?

If you are free Thursday evening or Friday I could take a look at it
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