Installing a 424 Swiftamatic in an L - MyTractorForum.com - The Friendliest Tractor Forum and Best Place for Tractor Information
 
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post #1 of 6 Old 04-10-2019, 04:35 PM Thread Starter
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Installing a 424 Swiftamatic in an L

I would be interested in talking to anyone who has changed out the gear set in their L (or C) from the stock 8 lead to the 6 lead 424 unit. Looking to slow down the standard L8 (or C8) ground speed to something close to an L w/ geared wheels in low axle range. Just won the center section w/ ring gear and the correct worm on e-bay and wondering how tough it was to make the change.
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post #2 of 6 Old 04-10-2019, 05:06 PM
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Re: Installing a 424 Swiftamatic in an L

Hello nhgravely,

I have plans to do the same conversion on a 1968 C-8, and have the parts purchased from a forum member.

I found some old posts about this swap using the google search, and I put up a post asking for info / parts late last year that got some good replies.

My understanding is that the engine, and front (advance ?) housing have to come off, and at least one axle housing.

My unanswered question at this point is do I need to have extra shims on hand to setup the axle bearing clearance since I plan on swapping the entire assembly, and cannot believe I could be so lucky as to have it all go back together without having to make adjustments to the shims.

Now that I have some time on the machine (bought late last year) I suspect that the crank is out of phase, so if I go in for the gears i'd better split the cases and trim out the crank.

Hope you find, or get replies to satisfy your questions better than I have done.
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post #3 of 6 Old 04-10-2019, 09:11 PM
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Re: Installing a 424 Swiftamatic in an L

I have done the conversion to a 58 LI so I did not have to swap the lead worm. Doing the conversion on a L8/C8 will require removal of the advance casting and engine. That is needed to remove the eight lead worm and install the six lead worm.

The differential from the 400 series will fit right into a L8/C8 if they have the same cog shifting components. The early models were 5 cogs and the later models are 3 cogs. You must keep the shifting clutch from the L8/C8, the shifting clutch from a 400 will not work in a two-wheeler, nor will the thrust pin in the center of the differential. The 400 series thrust pin is shorter than a two-wheeler. There could be a left side bearing difference between new differential and old, there were changes, but you can either swap the left side of the differential or the bearing itself.

As far as the axle housing shims, you probably have enough with two new axle housing gaskets. The shims are used to adjust the 008 - 012" end play on the differential and best done without one or both axle shafts in place. Bolt the axle housing down with new gaskets and shims using three bolts in a triangular pattern. You now reach in the advance casting opening with a long pry bar and try to wiggle the differential side to side. More than a wiggle is too much, remove shims. As the differential carrier bearings worked over the last forty to fifty years, they wore a tad, hence fewer shims needed to achieve end play. If you think you might be too tight, just reach in a try turning the lead worm by hand. It should turn the differential with ease.

Next you install the axles and bearing caps. Make sure you have the thrust pin in the differential. The length of a two-wheeler thrust pin is 1.250, if your pin shows a lot of wear, replace it. The axle end play is also 008 - 012" but it can all be adjusted from one side. That is done by adding/removing shims behind the bearing cap. Remember, if the thrust pin is worn, then axle end play will require more shims. Just push/pull on one axle shaft and look for that wiggle. It is a great time to replace leaking axle shaft oil seals, but they run about sixteen dollars each and you need two per side.

Good luck, Roger

Faux Pas are my forte

Last edited by beaner2u; 04-10-2019 at 09:16 PM.
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post #4 of 6 Old 04-11-2019, 10:53 AM
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Re: Installing a 424 Swiftamatic in an L

Thanks for posting Roger,

I really appreciate the level of detail you put into your replies.

You sir are one of our treasures, and an inspiration.

Best regards
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post #5 of 6 Old 04-11-2019, 10:59 AM Thread Starter
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Re: Installing a 424 Swiftamatic in an L

Thanks
Great info.
Will look over the unit when it arrives and decide which tractor will go under the knife.
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post #6 of 6 Old 04-16-2019, 04:09 PM Thread Starter
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Re: Installing a 424 Swiftamatic in an L

Got the 424 gear set yesterday; looks really good with little to no wear. Inside of the bronze gear looks brand new and the 4 center gear sliders have no visible wear. Slider clutch is the three dog one, so I will have to check both C8's to see which one has a three dog slider (they should both have one as the 424 donor was said to be a 1968 and both C8's were made in 1969). The 424 axles were held into the center section with square snap rings so these were removed. I can see why the center thrust pin is shorter in the 4 wheeler; it's because of the these snap rings holding the axles in towards the pin.
This should be interesting.
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