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Thread: Doing some research on a 1963 wagoneer for a book

  1. #101
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    The double clutching is mainly done to keep from grinding gears I assume where the synchronizers are worn, but some of the really old trucks may not have had them at all. I tore a tranny apart on a 48 KB-5 International truck once and I don't believe there were synchronizers in there.

  2. #102
    Super Moderator bmorgil's Avatar
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    The Jeeps we mess with are not synchronized in first. Something I forgot more than once with "Senior Chief" on board. I was immediately informed of my lack of knowledge on my equipment! In all seriousness, if you are not used to having an un-synchronized 1st gear and, you drive a lot of stick shift cars, you are going to grind it once or twice in your time. To get it into first if you are moving, you must "double clutch".

    For the "Pyro" here's a brief explanation. If you are traveling at a steady speed and you hold that speed, the engines RPM would change depending on the gear you were in. In other words lets say for argument purposes, at 25 MPH in first gear the RPM would be 4000. In 2nd gear at 25 MPH it would be 2300 RPM and in third gear it would be 1400 RPM. So if you are driving along at 25 MPH in 3rd and you shift it down to 2nd, you push in the clutch and as you pull the snifter from 3rd to 2nd the Synchronizer picks up the speed of the 2nd gear and spins it up quickly to that 2300 RPM it needs to be at or, the gears would collide because they are spinning at two different speeds. Now if you desire 1st gear in our little antiques, the game changes. At 25 MPH we need 4000 RPM to be in 1st gear. In second we are only spinning the gears at 2300 RPM. A big difference from the 4000 RPM needed for a smooth shift. If we try to shift there is no synchronizer for first. The mismatch in RPM of over 1500 RPM, will cause damage, noise, chastising, humiliation and grief.

    So... you push in the clutch, pull the shift lever into neutral release the clutch and rev the motor (the classic double clutch move) bringing the engine RPM up to the required 4000 RPM for the match. Depress the clutch again and complete the shift then release the clutch in 1st gear. Nothing to it right! It requires practice and knowledge of the RPM's you need to match when shifting at different speeds. It is a blast when you can do it. As an Experimental Test Driver for Spicer, I drove quite a few un-synchronized multi speed transmissions, From 3 speeds to 28 speeds, no synchronizers. The sound of flying through the gears with the double clutch "jamming", is very cool to say the least to a "Gear Heads" ears.

    There is an old Movie with Steve McQueen called "Bullitt". As he fly’s through San Francisco in the most famous chase scene ever, he is JAMMING on those gears! He was a real Racing Driver and an Actor well versed at transmission life during long races. Though he didn’t need to, (his transmission was synchronized in all forward gears) he was doubling the SH#@ out of that Ford's 4 speed. This was an old technique used in endurance racing to get maximum life from the transmission as you beat it to death. The sound of Steve shifting is as good as it gets. You hear the distinct RAAH-RAAH as he revs the motor during the shift.

    Now there’s more than you wanted to know!
    Last edited by bmorgil; 02-17-2020 at 07:02 AM.

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