Author Topic: Welded 3rd and 4th gears  (Read 1040 times)

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Offline Buggytime

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Welded 3rd and 4th gears
« on: May 22, 2014, 07:22:45 AM »
I have a Type 1 IRS transaxle with an "AT####4" code, and I was wondering if you can weld the 3rd and 4th gears in these models?
I am running a stock clutch and pressure plate setup with a 1968cc motor.  1st and 2nd gear don't slip when I step on it, but when I drop it hard into 3rd, something spins and I think its the gears because it doesn't do the same in 1st and 2nd.
So I am wondering if my transaxle is worth rebuilding or if I need to find a new one.
I am also planning on buying a new 1700 lbs clutch and pressure plate when I deal with the transaxle, unless anyone has a used one kicking around.

Thanks,
Kevin

Offline Hansk

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Re: Welded 3rd and 4th gears
« Reply #1 on: May 22, 2014, 10:06:53 AM »
Not sure what gears are in your trans but if they are press on hubs I would think you would need more than a stock clutch
to spin them.  I've never experienced it my self but I would think if you did spin a hub , the clearances would go away and the trans would try to seize up . It's also hard to imagine that you would have spun both 3rd and 4th and the trans would continue working normally otherwise .  I would suspect your clutch is slipping which would show up more in higher gears at first.
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Offline Cameron

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Re: Welded 3rd and 4th gears
« Reply #2 on: May 22, 2014, 03:16:37 PM »
I would tend to think that the clutch is going away, rather than the hubs spinning.
Either way, the motor has to come out. So, pull the motor and look at the clutch assembly for signs of slipping, burnt disc and blue flywheel and pressure plate.


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Offline Buggytime

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Re: Welded 3rd and 4th gears
« Reply #3 on: May 23, 2014, 06:29:55 PM »
Thank you for the response guys.  I assumed that there would be more torque on the clutch in 1st and 2nd rather than 3rd, so that's why I assumed it was a spun gear (Someone put the spinning 3rd gear in my head).   I think I read somewhere that the "AT#####" case has a factory braised (sp?) 3rd and 4th gear to the shaft unlike earlier years with the pressed on gears.  At least I have a direction to look now.

Thanks,
Kevin

Offline Bruce

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Re: Welded 3rd and 4th gears
« Reply #4 on: May 24, 2014, 04:45:19 PM »
1st and 2nd gears are manufactured from one piece of steel, so there is no welding or pressing to be done.
early 3rd and 4th gears have their synchro hubs pressed onto their gears.  These are the gears that get welded in applications with more hp than stock.
late 3rd and 4th gears (like in a SSC) have their hubs furnace brazed in place.  There was a fairly large number of third gears that had bad brazing from the factory.  When you have this, third gear is a neutral. 
Late Bus 3rd and 4th gears didn't get the brazing.  Instead they got electron beam welded.  These never come apart.

The fix for the gearbox in question if the 3rd gear is defective is a simple 3rd gear swap.  Plus rebuilding all the other worn out stuff on a 40 year old gearbox.

 

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