Stephen Payne’s Winning Edge Information Page

Welcome to the Polar Motorsports International Frequently Asked Questions (FAQ) discussion board. As many of you are aware Polar clutches have been dominating the Junior Dragster strips for years. Stephen Payne of Carleton Place, Ontario, Canada is the leading expert on clutch setups and performance optimization. Daily, Stephen get calls racing enthusiasts who just want to win and Stephen guidance has in turn helped many Junior racers to win. Polar is made in Canada with exacting precision, if the clutch you are buying is not a genuine Polar then you maybe compromising your potential to win.

Weekly you will find that the new Polar website will be providing you with helpful tips to get optimal performance from your car and to maximize your child’s racing experience.

Questions:

1. What do I do when my belt slips when the car takes off?
2. How do I change my stall(engagement) RPM?
3. How do I change my shifting RPM?
4. Where should the belt sit in the secondary?
5. How tight should the belt be?
6. What hole does what when it comes to secondary spring tension?
7. What is Overdrive?
8. I put overdrive shieves on my clutch but for some I don’t get it into overdrive, what do I do?
9. What is the POLAR REVOLUTION?

Answers:

Question #1- What do I do when my belt slips when the car takes off (in the hole shot)?

This is caused by two things.

1. First, the belt clearance between the shieves is not enough. This causes the belt to engage on the stall part of the ramp.
   
   The stall ramp cannot create enough load to maintain proper RPM, so the engine rev’s higher until the roller gets on the shift part of the ramp.
   
   When the motor is trying to shift on the stall part of the ramp, the car will move very slowly. As the roller gets to the shift part of the ramp, the motor will pull down, and the car will take off.
   
   To cure the problem, increase the belt to shieve clearance. This can be done by:
   
   - adding a shim between the fixed face and primary post, typically .03”.
   - or by back cutting the square washer .03”, to allow the moveable shieve, to move back away from the belt. A shim should also be added under the cover the same amount, to keep the relationship correct.
   
   If the belt has clearance between the shieves, the cover can be shimmed out, to move the roller closer to the shift part of the ramp. I would add .02” shim at a time, up to two shims.
   
   On a Pro clutch, remove the moveable half, and add a .02 shim to the belt clearance shims. One or two shims should do the job.
   
2. Second, the other possibility, is the secondary spring is set to soft, or the cam (helix) is to steep for the load. This will cause the belt to drop into the secondary, at the hit of the throttle. In this case the car will move, the motor will over rev some, then the motor will pull down, then the motor will pick back up and the car will continue the run fine.
   To cure this problem increase the spring tension one hole at a time, up to six hole.
   
   The other alternative is to cut back on the cam angle two degrees at a time, eg. from a 42 degree to a 38 degree. This should improve the situation normally.
   
   If you already have the spring correct and the smaller cam does not help, then the amount of weight you are pushing may require a lower gear ratio, or lower stall RPM, to reduce the load the secondary sees at the start.

Question #2. - How do I change my stall(engagement) RPM.

The stall RPM is a function of the stall angle on the ramp, and the type of spring in the clutch.

The bigger the number, the lower the stall RPM for example an 18 degree stall angle will have a 2-300 RPM lower stall than a 15 degree, and vice versa.

A stronger spring will raise the stall and a softer spring reduces the stall.

Going from a purple to a green, is a stronger spring, and the stall will go up, approximately 3-400 RPM.

Going from a purple to an orange is a softer spring, and the stall will go down 3-400 RPM.

Question # 3 - How do I change my shifting RPM?

If you want to change the stall or engagement RPM, this is difficult.

Increasing or decreasing spring pressure is an easy way.

If you have a purple, drop to an orange, will lower RPM about 300.

The other alternative is to change the stall angle of the ramp. Going from an 18 to a 12 will increase stall RPM about 5-600. A 15 will be half as much. Also, going from a 12 to 15 or 18 will lower the stall the same way.

Question #4 - Where should the belt sit in the secondary?

With a smoother outer belt, the outside of the belt should be flush to out of the secondary 1/32.

With a top cog type belt, the bottom of the grooves on the outside of the belt should be flush or protruding out by 1/32.

Question #5 - How tight should the belt be?

Belt tension is set by the centre to centre of the motor and driven clutch. There are two ways to check this:

1. Put a straight edge on top of the belt. Push the belt toward the ground and measure the deflection from the straight edge. Deflection should be 1 ¼ to 1 ½.
   
2. Hold the driven clutch with your right hand. Take the belt in your left and push it towards the driven clutch. The belt should slide around the driven clutch with a bit of effort. If it slides easily, then tighten up the belt. If it is very hard to slide, loosen the belt.
   
   

Question #6 - What hole does what when it comes to secondary spring tension?

The holes are number 1 thru 8 from lower left to right when looking at the cam (helix) from the driver’s side of the car. As you increase the spring tension moving up a number, will increase the side pressure on the belt. This gives the secondary better control over the belt force so it will not open the shieves as fast.

When “bracket racing” this will help with the consistency.

In 330 “heads up” the lower the spring pressure the more efficient the clutch system will be, so it is best to have the lowest spring pressure you can use for your track conditions.

If the car spins the tires easily, more spring pressure will reduce how fast the secondary opens and reduce the amount of “pull down” the engine will get once the tires hook-up.

Question #7 - What is Overdrive?

Overdrive is a term used to describe when the secondary (driven) clutch is turning faster than the primary (drive, engine) clutch.

Question #8 - I put overdrive shieves on my clutch but for some I don’t get it into overdrive, what do I do?

There are a few things to remember when you want overdrive;

1. the car has to go fast enough to allow the primary clutch to shift up into overdrive
2. The higher the RPM of your engine, the farther you go before your clutch can shift all the way.

Let’s start with an example. A 7.90 car runs 16:80 gear ratio and goes through the lights at 8000 RPM and shifts at 8000 RPM. In this case, the car is not running out of clutch, so changing the shieves will not get overdrive.

If I change the gear ratio the 16:85, the engine shifts at 8000 RPM and crosses the line at 8600 RPM because around 550 feet the clutch would be fully shifted out and the engine would start to rev higher as you finished the last 1500 feet of the track.

If you put overdrive shieves on, the clutch could continue to shift to the end of the track, and the RPM would be 8000 at the finish.

Overdrive will usually improve the E.T. on a car, because now you can use a lower (6.00 to 6.50) ratio to help move the car.

The 330 cars use 15-25% overdrive to get maximum acceleration; they are not worried about consistency. If you have a heavy car with low power, overdrive will definitely help.

A light car with good power should not need overdrive. The lower gear ratio will help promote tire spin. The car will need more weight to slow it back down. The taller (faster) the gear ratio, the less weight you need. Cars seem to be more consistent if you reduce the chances of spinning the tires. More weight will usually reduce your MPH.

Question #9 - What is the POLAR REVOLUTION?

The new “Revolution” is a clutch for demanding racers. It will take a driver from 12.90 to 7.90 with minimal changes.

The genuine Polar Revolution clutch, will increase performance from Briggs Raptor to a fire breathing Whaley Motorsports 330 Thunder.

It incorporates the Polar “TRU Support” roller secondary, to promote back shifting and improve consistency.

The primary shieve angle will allow overdrive if required.

All the industry leading features you expect in a Polar are included:

• hardened alloy steel ramps,
• hardened and composite bushing roller will outlast brass.
• billet arms are as strong as any.
• Polar’s own original ramp roller design for best belt grab and easy tune-ability is the only way to go.

At Polar Motorsports International, we have more experience with variable speed drives than any other clutch manufacturer. We pioneered the first “Junior Dragster Specific Clutch” to take advantage of the torque of a four stroke. No competitor has come up with a design that promotes more axle horsepower than Polar.

Ask the top 330 racers. They use what works best, Polar has made more passes and won more races than any one else. With many similar parts to the Polar Junior, the Polar Revolution design is well proven and the new appearance sets it apart from the rest.

We were the first clutch, so make a Polar Revolution your last clutch.