Vintage snowmobiling

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Contents

[edit] Introduction

Vintage snowmobiling was designed by retired Snopro racers who wanted to relive their racing experiences and memories, but did not have the physical stamina and money required to field one of their old Sno-Pro sleds. The racing of vintage snowmobiles has grown into a major sporting event on the Canadian prairie over the last few years.

[edit] Basics of Racing

[edit] Rules

  • It is acceptable to cut, port and plane
  • The points stay in
  • The muffler is stock
  • The race is 100 miles long
  • Depending on OEM carb type, racers are divided into two classes: HR or HD

There are additional rules for safety and reduced expenditures.

[edit] Costs

There is a $50 entrance fee since a snowmobile that is competitive and ready to race can cost 2000 to 3000 dollars. The first race had five entries, paid $125.00 to win, $75.00 for 2nd and $50.00 for third. With the increased popularity of the sport, it is not uncommon to see up to 50 riders, which results in larger cash rewards.

[edit] Strategies

While the majority of racers race in a team of two drivers and one pit person, it is possible to race without a team. A race usually takes over three hours with one or two stops to refuel. This sport can be begun by anyone who finds three other people with older single sleds that run and designates a 2 mile course. It is likely that other people will soon join in due to the popularity of the sport. Different snowmobiles are seen at these races and include Auto-Ski, Massey, Cats, Skiroules, Rollo-Flex and TNTs.

[edit] Restoring a vintage snowmobile

After buying a vintage snowmobile, or if you have one, it will need to be restored.

[edit] Axle and Bearing

The drive sprocket pulls the track over the top from the back resulting in the snowmobile pulling itself over the snow, rather than pushing itself.

To replace the bearing, remove the rear drive wheels from the shaft. The rear wheels are where the first pressure will be felt by the chassis. Removal of the rear axle is also sometimes required. A common snap ring set of pliers help with the process, but are not mandatory. Loosen off the track, remove the bolts and tap the wheels loose. Most wheels have the bearings inserted in their center. Pop out the ring and push the bearing out. All bearings are sized according to inside diameter (ID) and outside diameter (OD) and width. Some bearings have numbers on them but if not, the ID, OD, and width can be measured and a bearing can be found at a bearing supply shop with this information. A new bearing should be installed using the process above, in reverse. It is useful to make some simple drawings to assist in the reassembly.

[edit] Track

Next, leave the track loose and check the drive axle. There are two bearings down there that need inspection. The one in the chain case runs in oil but the other one will most likely be dry. Take out the exhaust and chain case. Catch the oil as well as you can and clean the whole case. Solvent works best on chain cases along with a paintbrush. Put a drip pan under the chassis and to reduce the amount of solvent needed. Loosen the chain tension adjuster off and grasp the bottom gear, pushing and pulling it to discover bearing wear. If there is no play the bearing is most likely in a satisfactory condition. The dry bearing should be replaced because it is one of the most problematic bearings for riders. Most bearings sit in a cup of sorts, secured by three bolts. Some use a lock collar bearing and others are slip fit. Looking at it closely will reveal how the bearing is held in place.

[edit] Chain Case

After that, you can begin to tackle the chain case. To maximize power, the power must be taken off the drive axle at a 90o angle. This means that the alignment of the top and bottom gears must be true. Use a straight edge to check and if they are not then use spacers to align them. The snowmobile's chain needs to be set at the correct tension. It cannot be too tight, but if it is too loose, it will slip. To properly adjust a chain, pull on the drive side of the top gear to remove any slack. Set your tension adjuster to allow you about 10 mm chain movement. It is important to oil the chain case with any synthetic gear oil and add a sealant to prevent leakage because a chain case will not run properly when it is dry.

[edit] Track Tension

It is also important to adjust the track by taking off the belt and jacking up the rear end of the sled. Tighten both tension adjusters evenly until you get a track that just hangs off the rails a bit. As with chain tension, being too loose will make it skip and too tight will also causes problems. The secondary clutch should be turned by hand, until the track is free moving with no tight spots. A tight spot will need to be fixed or it will lead to diminished horsepower. A sign of a track that is too loose is that it slaps up against the tunnel during a test run. The first few test runs should be easy going until you can determine that the track tension is close enough that it won’t skip on the drive cogs, which could cause track damage. A longer cleated track smoothens the ride more than a short one, but adds some drag.

[edit] Secondary Clutch

Secondary clutches need to have enough tension to give adequate belt grip. Usually a breakaway force of 3-5 kg/m is normal. More will hold your shift back, and less will let your primary clutch run amok. Clean up the ramps and springs and lube the main shaft. Removal may or may not be required, most can be cleaned right on the vehicle. The spring fits in holders both ends and the spring tabs should be in the holes, making everything go in and out smoothly with about a 3+ kg/M push.

[edit] Primary Clutch

Primary clutch removal will require a clutch puller tool. It can be helpful to take out the engine at this point and drop it on the bench. Remove the carbs, the pipe and the starter, also unhook any wiring, (drawings or photos of the original configuration are a good way to get things back to normal if you are unsure). Once the engine is out and stripped, it can be taken to a local dealer to have the clutch pulled. Most serious backyarders have their own set of various clutch pulling tools and depending on what your local dealer charges, you may want to join their ranks and pick yourself up one. They cost roughly 30 bucks for the tool. It is important to know the clutch type before working on it. Some are spring loaded. Find the worn parts and replace them as needed. Clean and lightly lube all moving parts and make sure the unit slides together and apart under spring pressure. Used parts work fine so try the local wreckers. Replace until you are happy with a nice tight smooth clutch. Be aware when lubing clutch parts there are areas within the clutch that are designed to roll against one another, not slide. Do not lube these areas, it will cause the rollers to slide where they are suppose to roll, wearing a flat area on the roller.

[edit] Steering

Steering is a matter of starting at one point and working out the slack as you go. Most older sleds used common farm parts when possible, probably because a lot of the older makers were also farm equipment manufacturers. Some of the more simplistic sleds simply bent a shaft and pinned it through a steering arm. Luckily, any worn or broken parts like this can be easily fabricated. Farm supply or sled wreckers usually can outfit your sled with a set of reasonably tight steering joints. The rest of the bushings should be cleaned and replaced if possible, or at least shimmed up. The total amount of play you feel in your steering system is “stacked up” play. The trick is to recognize that play as an accumulation, and not usually the result of one issue in one location. Systematically start working out all of the play you can out of each joint.

[edit] Alignment

To adjust steering alignment, place a straight board tight up against the left side of the track, and be sure to let the board stick out in front of the sled at least as far as the ski tips. Center your steering (handlebars), while sitting on the sled. Adjust the left ski to be even (parallel), with the board, making sure the steering (handlebars) remain straight. Measure across the skis and set a 1/8 inch tow in.

[edit] Brakes

Brakes are best cleaned up and lubed to work freely. Pivot points and cable rub points are most likely to need attention. The brake let off is as important as the actual stopping power. The brake should release quickly with no drag. A common degreaser can be used to clean up brake pads. Pads themselves are usually available or can be fabricated by most brake shops. Hydraulic brakes will require a brake kit to rebuild, or at least some of the rubber parts. The application is strictly automotive and any high school auto text explains it all. Because brake fluid is an effective paint remover, paint or decals should be covered up and protected.

[edit] Electrical

Electrical systems are best tackled with a schematic in hand. Most older sleds will be a points and condenser style, (fixed magnets usually whirl around a coil system). Almost universal is the setting of .012 inch to .014 inch on the points gap, set points to open on the “F” mark. Use a cigarette paper to clean and set the break point. Drag the paper through the closed points a few times to ensure a good clean contact. Leave the paper between the points and rotate the engine past “F”, while gently tugging on the paper. When you feel the contacts release the paper, that is usually when spark occurs. Note the “F” position and the Pointer Mark relationship. Adjust to align timing.

[edit] Manual Reference

Working on the engine should not be attempted without a specific manual. Engine makes are not the same so the maual you get must match the model you have. Each manual will require specifications unique to itself, as well as a mention of required tools. Manuals usually cover A-Z rebuilds and refer to specific machine shop tasks (re boring cylinders, honing, etc). Any competent dealership or local sled repair shop can direct you to the local expert machinists. Parts such as gaskets, seals, and bearings can be found at parts outlets. The most expensive parts come from the dealerships but they usually fit the best. Aftermarket parts may not have the perfect fit or colour but are cheaper and for older models can be the only parts available.

[edit] References

[edit] Related Pages