78 Liquifire rebuild!

[400brian]

It has been a while since I posted anything about the 78 LF project. My wife retired from a 43 year career in dental hygiene in August, and since that time we have been fishing in Eagle River, hanging out with the grandkids, and traveling a little. Oh, and at the grandson's urging, we are working on a 1937 JD B that has been in the back of my shed for 40 years.

The plan had been to put the sled on the snow this winter, but it is clear that is not going to happen. Nevertheless, I will just keep plugging away at it.
Recently I have returned to cleaning the black goo out of the pan, straightening the ribs in the pan, and cleaning the top of the tunnel where there had been a lot of corrosion under the seat. I finally pulled the chain case out to get things clean, found a fish hook under it.

From the time I bought this sled back in 2009, the plan has been to build this into a custom rider. Up until this point all the sleds I have worked on were kept pretty much original. My plan was to build the sled as a Cross Country clone, albeit a 440 powered one.

One of the things that a Cross Country sled might have on it was a kit to replace the plastic chain tensioner in the chain case with a steel unit. I knew I had a steel tensioner on hand to put in the case, but I had forgotten if I had purchased a complete case to get it, as this was an ebay purchase from many years ago. Joe and Wade were advising me to ditch the 78 case and put a 80+ case in, rather than do the modification.

You never know what you will find in these old sleds. When I disassembled the brake on the 78 case, I found someone had been in it before me.
The sled is showing less than 900 miles, but it was obvious that the brake pads had worn out. To remedy this, a washer had been placed under the moveable pad, while the fixed pad was ignored. Thus the disc had been running against the side of the case, pretty much making junk out of it.

Today I took a look in the stash and found I did indeed have a 80+ case on hand. Side by side you can see the difference in the two cases ( 80+ top ).
In addition, the brake pad can be replaced from the top on the 80 case without a lot of disassembly. Swapping in the 80 case will give me the steel tensioner without any additional effort.

[400brian]

Continued working on getting the inside of the pan clean. I have also been massaging the dents out as I go as a distraction. The ribs in the center of the pan are with few exceptions always messed up, and the bump out under the chain case is generally as well.

I am making progress. I had purchased a gallon jug of BrakeKleen, and a gallon of a paint prep product. Neither were cheap, but the paint prep product doesn't smell nearly as bad, and is more gentle on paint. Power washing or steam cleaning would have been a better option, but we are long past that idea now.

With the dents worked out of the area under the chain case, and the black goo cleaned out of that corner of the pan, I cut a new cork gasket for the 80 chain case and bolted it in place. I have a pair of new oem style bearings coming. Once they are here I can install the jackshaft, hopefully for good.
I found a good brake disc in the pile, however the 76-77 discs appear to be slightly different from the 78. The 78 disc has two keyways cut into the hub, one for the key, and the other for an anti-rattle clip. I had seen that little doo-dad previously on a 78 Spitfire.

I am getting closer to rolling the sled on its back to begin the track and suspension install.

[Cdnturboz]

Looking good!

[400brian]

Small progress adds up up if you can keep at it.

Today I gathered up the new bearings, the cork gaskets I had made, and started working on getting the jackshaft in.

I had sanded the original 78 brake disc considerably smoother than it had been, and decided it would work.

Three hands would help here, but I got the bearing with a cork gasket between the flange and the case in, remembering to install a new o-ring between the flanges. The carriage bolts used here are barely long enough. The 80 case uses thin nuts with a ring of fold over locks to secure the upper bearing flange. Add in that you need to compress the o-ring a bit to get the nuts started , and you have a challenge.

The shaft turns smoothly, so I am calling it a win!

The first thing I did after I bought this sled back in 2009 was send the seat to John's Upholstery to be re-covered. It has been sitting around gathering dust, so just for fun I cleaned it up a bit and set it on the sled. I haven't decided if I will use it or not, I may put a two up seat on the sled so I can sit further back, time will tell.

I believe I have a Kelsey Hayes brake caliper to go with the rebuilt master on its way, that will give me the look I want compared to the polaris caliper I had been considering.

[400brian]

So I am now looking at the bottom side of the sled. There is a lot of work to do before this will be back on its feet.

I brought the track I intend to use into the garage tonight. It will not be used "as is" I have at least a couple of things to do to it.

I took the heat exchanger out. This design proved to be problematic back in the day. The fins would pack with mud or other debris under the right conditions, and then the engine would overheat. The 80+ Liquifires exchangers were smooth. I plan to mess with this one a bit.

[nick80lf]

Very interesting track you have there.

[400brian]

The track is an Arctic Cat part that a number of guys have used to convert Deere sleds to a rubber track. They are obsolete, but used ones are fairly common. This particular track previously had been on one of Rainville's racing projects.

[400brian]

This is the next custom part going into the build. I am thinking the first appearance of the hex driveshaft was on the 77 Liquidator.

The hex shaft was used on the Trailfire, Sportfire, and second gen LF. However, the drivers we need for a 121" track are 2.52 pitch. Deere made a run of hex shaft 2.52 drivers so the racers could run the thinner 2/3 cleated production tracks in 77 and 78 if they wished. The NOS supply of the Deere drivers is pretty much dried up, but Wahl Racing does still have them in their catalog.

Both pics show the NOS Deere drivers. The top pic is the parts that are going into my 78. The hex shaft is NOS as well, but it shows some shelf wear and rust. The outside Deere drivers bolt onto the axle, while the center floats between spacers.

The bottom pic shows 78 LF builder Pat Scott's solution back in 2011. I assume Deere used aluminum spacers, but do not know for sure. The Wahl drivers are not drilled, they are press on.

There is nothing new going on here, this rubber track conversion was widely discussed on this site over 10 years ago, and a number of list members have done this.

[Popcorn popper]

Awesome work. Coming good

[400brian]

There has been some discussion about this situation. The hex shaft was first used on the 76 - 77 Liquidator, and the 78 CC also used it. The ones used on the Dator and CC were the white drivers with the aluminum hubs but they were also 3.29 pitch. There may have been some black plastic drivers made in 2.52 with the aluminum hubs, but are not common. These all plastic 2.52 drivers were most likely part of the field upgrade kits that were made available in 78 to update your 78 Cyclone or Liquifire to the hex shaft. I am told it is not uncommon to find 78 440 LFs with the hex shaft installed.

[400brian]

Pat Scott made me these plastic pipe spacers 10+ years ago. I assembled this mock up with a round shaft and drivers, they seem to be the same dimensions as the JD hex drivers.

The 121 x 16 track does not leave much room for error. I want to check everything I can before I press the hex drivers onto the hex driveshaft.

[nick80lf]

If I remember correctly the 78 liquifire charity sled from several years ago had a hex shaft. Had one hell of a time trying to get one of the drivers to budge.

[400brian]

Busy time of year, but I did get a little time in the garage. I am replacing the original tunnel protectors with a set of Garlands sold by Wahl Racing.
They are a "U" shape which should make for easy pop riveting. They are an inch tall, and 1 1/4" wide. They were a bit longer than needed, so I had to cut them to length with a hacksaw.

I want them to sit directly above the track clips, so they have to be located a bit closer together than the originals to match the Yokohama track I am installing. When I replaced the tunnel protectors on my 340/S some years ago I used protectors that were 3/4" wide x 1" tall. Those more closely resembled the original Deere part. On a sled with a full plywood bottomed seat, you kinda want to have the heads of the rivets on the top of the tunnel with the body going down. So for the 340/S I had to deepen the counter bores of the holes in the plastic so the pop rivets would reach and allow the use of backers. With the 78 seat only having plywood at the sides, I can rivet these protectors on from the underside. If I later choose to run a two up style on the sled, I'll have make some relief holes in the plywood to clear the rivets.

[400brian]

So I finally got the tunnel protectors riveted in. The rear half were put in from the bottom side, and the front half were put in from the top side so there is nothing to wear into the fuel tank. I had to drill the heads off rivets to get the size backers I needed.

The steel front suspension arm spacers have been removed. The arms need to be re-located to the rear a bit for the CC suspension, so new spacers need to be fabricated.

And last, I am shaving down the fins on the bulkhead heat exchanger. They only used this design one year, the racers found that the fins would pack with mud and become useless, so in 1980 they came out with a smooth version. I have one, but to use it would require the hose fittings be re-located ( welded ) in a different orientation.

[AirborneX4Special]

Been a long time since I saw one of those but I remember my reaction as if it was yesterday.