Vintage snowmobiling
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[edit] Retro Racing Around, 2006, v1
[edit] Getting In
Over the last few years racing vintage snowmobiles has grown into a major sporting event on the Canadian prairies. What started with 3 or 4 older ex sno-pro racers (and their ego clashes), is history. Born from the utterance of thinly veiled threats of dominance within the geriatric group, the event has grown by leaps.
“Ya know, I still have an old Sno-Jet.” Not able to leave it at that, his buddy responded, “Yea, and I still have a Cat that will blow your socks off.” And away it went.
[edit] Introduction
None of us had the physical stamina, and the $20,000, it would take to field one of our old Sno-Pro [Sled|sleds]. But we all have the memories of the race, the thrills, the satisfaction and the camaraderie of the old days. (I’m stuck somewhere in the early 70’s.) Mere interest wasn’t all that was required however. What to race? What to race and still survive to function as grandpa!
“Singles.“ someone suggested. “Old ones, as old as say... 1973, that should put everyone on even ground.” “Besides”, another dinosaur added optimistically, “How fast do they go anyway?”, convinced that 70 km/h still represented safe.
[edit] Basic Rules
Because it all started out as a race, and because we all believe that a sled should be modified just short of a failure to start, some unusual rules spewed forth:
- Yes you can port or cut or plane or do whatever you want.
- The points stay in.
- The muffler is stock.
- The race is 100 miles long.
- There are also 2 classes, HR or HD, depending on your OEM carb type.
Eventually we added a few more rules for safety and to put a lid on the expenditures.
[edit] Costs
Still, realistically, a good sled costs about $2000.00 - $3000.00 to roll up race ready and competitive. A $50.00 entry fee and a 100% payback policy keeps everyone interested. The first race had five entries, paid $125.00 to win, $75.00 for 2nd and $50.00 for third. That was five years ago! Now it’s not uncommon to see up to 50 riders, you can do the math.
[edit] Strategies
So, want to do it around your place? Sounds like fun, doesn’t it? Find three other people with older single sleds that run, designate about a 2 mile course and get at it!
Most racers team up for two drivers and one pit person but some go the distance solo. Proper perspective is cast when you realize that with one or two gas stops you’re gonna be out there about 3 hours, plus.
Believe me when I tell you that once you do it, the crowds will grow. It’s contagious.
People will show up with the weirdest sleds you‘ve ever seen, Auto-Ski and Massey abound. Cats, Skiroules, and Rollo-Flex run strong, and TNT’s are always a good bet. They still exist in numbers, especially if you listen close to the crowds on race day. “I’ve got one of those.”, is probably the most common phrase you’ll hear.
[edit] Conclusions
So follow up, fix it up, and fire up a racer that will truly be close to your heart and the hearts of all the old sled heads around. It’s pure fun, (and you’ll get to use all your old racing tricks again). For more info please see: www.nearnorthsnowdrifters.com
Written by Gord Healy, Jan01/06
[edit] Retro Racing Around, 2006, v2
[edit] Drive Train and Clutches
So you did it, you took my advice and bought a new old sled. Unfortunately, you can’t just take it to the car wash and call it good. The old thing is going to need a complete going over, using common everyday tools.
[edit] Axle and Bearing
While you sit and contemplate the natural beauty of your beast, consider this, the sled pulls itself over the snow, it doesn’t push itself, as some would think. The idea is that the drive sprocket pulls the track over the top from the back. This is where we start. The rear wheels are where the first pressure will be felt by the chassis. You must remove the rear drive wheels from the shaft. Often removal of the rear axle will be required. No big deal. Just loosen the track right off, remove the bolts and tap loose the wheels. Most wheels have the bearings inserted in their center. A common snap ring set of pliers would help but are not mandatory for this. Pop out the ring and push the bearing out. All bearings are sized according to inside diameter (ID) and outside diameter (OD) and width. There will be a number on your bearing and if not, measure the ID, OD, and width, and visit your local bearing supply shop. 20 bucks should take care of it. Install them using the process above, in reverse. If during the disassembly you feel it is too complicated, just make some simple drawings to assist you in the reassembly.
[edit] Track
That done, you can leave the track loose, next thing is to check the drive axle. There are two bearings down there that need inspection. The one in the chain case runs in oil but its partner has probably not seen oil since the showroom. In order to continue the exhaust and chain case must come out. Catch the oil as best 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 you will use surprisingly little solvent and have a nice clean chain set up. Loosen the chain tension adjuster right off and grasp the bottom gear and push and pull in an effort to discover bearing wear. If there is no play the chances are it is OK. The other dry side is another story. Most bearings sit in a cup of sorts, secured by 3 bolts, some use a lock collar bearing and others are slip fit. Look at it closely and you will see how the bearing is held in place. This dry side bearing should be replaced. Over the years that bearing has been known to cause more grief than most other bearings on your sled. It must be replaced!
[edit] Chain Case
After that, you can begin to tackle the chain case. There are few principals of physics that apply here to maximise horsepower. Power must be taken off the drive axle at 90o. 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. Also a chain that is too tight is bad. To properly adjust, 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, (tight is bad but loose will slip). Any gear oil (synthetic), will work fine. Add just enough for your case. A good sealant will usually seal the case up but occasionally you get a leaker. Don’t let your chain case run dry!
[edit] Track Tension
Track tension is a matter of taste. I like mine loose until it won’t skip. Some guys run tighter but similar to chain tension, too tight is also bad. Take your belt off and jack 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. Turn the secondary clutch by hand, you’re looking for a free moving track with no tight spots. If you notice a tight spot, investigate and remove the problem or it will all add up to lost horsepower at the end of the day. A sign of a track that is too loose is one that slaps up against the tunnel during your first 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, this could cause track damage.
[edit] Secondary Clutch
Secondary clutches are next. Most guys run with just enough tension to give adequate belt grip. A frozen or limp secondary clutch is just useless. 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 sled. Notice that the spring fits in holders both ends. Make sure the spring tabs are in the holes and the whole deal works in and out smoothly with about a 3+ kg/M push.
[edit] Primary Clutch
Primary clutch removal will require a clutch puller tool. I usually pop out the engine at this point and drop it on the bench. Take off 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). Now the engine is out and stripped you can take it down to the local dealer and 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. Some clutch setups are spring loaded. If you’re not sure just ask your local expert. There are not a lot of different clutch types and most guys can tell just by looking. Be careful and ask, read or surf the net if you are unsure. What you need to do is to find the worn spots and replace as required. ‘Clutch work‘ requires basic parts replacement. Clean and lightly lube all the moving stuff 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] More to come; steering and brakes
Next on the agenda will be the steering and brakes, then on to the engine.
For now you will have lots to do, or at least something to think about. I must break off and tend to my new long track version of a vintage racer. My theory is that a long cleated track is better than short. We found this to be the case in 1983 with our Sno-pro oval sleds. A lot of the twitchy stuff is smoothed and I don’t think the extra cleats will add an appreciable drag. We’ll see.
Until next time. Gord
Written by Gord Healy, Feb 06/06
[edit] Retro Racing Around, 2006, v3
[edit] Steering, Brakes, Engine, and more
[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 and hope for the best.
[edit] Alignment
Steering alignment is easy. Place a straight board tight up against the left side of the track, 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. Work on the various pivot points and cable rub points to ensure a free operation. Be aware that the brake let off is as important as the actual stopping power. Make sure the brake releases quickly and with no drag. Common degreaser will clean up brake pads nicely. 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. Be careful, brake fluid is a very effective paint remover. Cover up all paint or decals.
[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
Before any engine work is started a specific manual is in order. Get the manual from a snowmobile dealer, library, internet, where ever you can. If you have a Sachs engine you need a Sachs manual, there is no substitute. Engine makes are not the same. Each will require specifications unique to itself, as well as a mention of required tools. Follow the instructions to the letter! 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, bearings, etc., can be had at any number of parts outlets. The most expensive parts come from the dealerships but they usually fit the best. Aftermarket stuff is cheaper for a reason. If perfect fit, colour etc, are not issues with whatever you’re replacing then aftermarket stuff is fine. If you have a Rollo-Flex, for example, you probably won’t find a dealer so the aftermarket route is the only way to go. Always shop for the best quality parts you can find. Restoration projects have many intentions, and ultimately you judge how good the stuff really has to be.
[edit] Conclusion
It has been my intention to share a few years of experience with you, condensed down to the usual problem spots. You can reach me daily at the Snowmobile Shop, 306-922-8034, (weekends are reserved for racing)
Enjoy your project and call if you need help and don’t be afraid to ask any questions you have.
Until next time. Gord
Written by Gord Healy, Mar 01/06
