Leaking 700R4. Need ideas...

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Jul 30, 2019
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So Cal
My '72 FJ40 has a 350/700R4 swap with Advanced Adapters parts. The trans pan was notched to make room for the front U joint, but it was notched too much and it leaks. I'm not sure how to solve this. AA discusses this in their instructions: 3. Toyota L/C Twin Sticks & Front Drive Shaft Kits - Advance Adapters - https://www.advanceadapters.com/3-toyota-lc-twin-sticks-front-drive-shaft-kits

"FRONT DRIVESHAFT CLEARANCE: ... Normally, proper clearance can be achieved by offsetting the engine and drivetrain 1/2" to 1" towards the driver's side. When using a transmission such as a 700R, this offset may still not provide enough clearance. We offer a front output transfer case yoke assembly that will take the standard 4-1/4" to 4-1/2" diameter flange yoke and reduce it to 3-1/2".

In my situation, the 3.5" AA yoke is already in place and the engine/trans were already shifted to the driver's side. Perhaps a new pan could be installed and the area where the notch is can be bent up to squeeze the gasket along the notch? Any ideas?

Here's the T-case and area of notch in the trans pan. (Note that the pan body has also been pushed inwards to clear the U joint)...
IMG_6186.jpg


Pics of the notch...
IMG_6185.jpg



Note that the trans housing was barely touched by the notch. The screwdriver is on the pan. The trans housing is above the gasket...
IMG_6191.jpg



IMG_6189.jpg



Could bending a new trans pan up along the notch successfully seal it? Maybe with RTV?...

IMG_6192.jpg
 

3_puppies

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Helena MT
WOW, that is close.
someone went to town with a grinder, the main body of the trans has missing material.
did you buy it this way?
you can try beating it back flat.
 
Joined
Jul 30, 2019
Messages
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Location
So Cal
WOW, that is close.
someone went to town with a grinder, the main body of the trans has missing material.
did you buy it this way?
you can try beating it back flat.
Yeah, I bought it this way, but I couldn’t see the notch until I dropped the front driveshaft. I thought it just needed a new pan gasket before that. It leaks too much.

I’m thinking a new pan could be beaten upwards to mate with the notched trans body. Hoping there’s enough clearance for that. Otherwise I’m not sure what to do.
 

Downey

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What I see is close to normal, i.e. slight pan modification and use of the smaller u-joint. Two issues though: (1) looks like the dent in the side of your oil pan is too deep, on 700R4's you can only dent-in the oil pan about 1/4" or you hit internal transmission pieces (can bend or dent-in a TH350 a full 1 inch). (2) very normal to grind top edge of oil pan and side of transmission aluminum flange 1/4" to 3/8" to clear smaller u-joint, but it looks like somebody got carried away with your tranny.

Know that very little clearance is needed between the universal joint and transmission because they never get closer to each other, a 1/18" would be good enough. You might try a fresh oil pan not modified so deeply, then use silicone glue with a new gasket. Just my 2 cents !!!!!
 
Joined
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Messages
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Location
So Cal
What I see is close to normal, i.e. slight pan modification and use of the smaller u-joint. Two issues though: (1) looks like the dent in the side of your oil pan is too deep, on 700R4's you can only dent-in the oil pan about 1/4" or you hit internal transmission pieces (can bend or dent-in a TH350 a full 1 inch). (2) very normal to grind top edge of oil pan and side of transmission aluminum flange 1/4" to 3/8" to clear smaller u-joint, but it looks like somebody got carried away with your tranny.

Know that very little clearance is needed between the universal joint and transmission because they never get closer to each other, a 1/18" would be good enough. You might try a fresh oil pan not modified so deeply, then use silicone glue with a new gasket. Just my 2 cents !!!!!
I was also wondering about the dent. I read that they shouldn’t be too deep. So hopefully no damage there as well.
Thanks for your input!
 
Joined
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Pennsyl-tuckey
Behind the dented area on your 700r pan is the transmissions internal mechanical shift-linkage assembly. Unlike the TH350, there is not much room right there to gain the necessary clearance for the front output flange so the dent doesn’t need to be substantial. IIRC and from personal experience, the shift cable will bind if the dent is too deep. Does yours shift ‘smoothly’ or feel like there’s binding??

In the attached photo (700r), the lower rt hand corner of the valve body shows a sleeved, spring-like fixture extending forward. This is typically where the shift cable will bind with overzealous ‘denting’ of the pan.

I’m assuming you’ll be replacing the pan and gasket sometime in the near future to fix the leak? When you do, take a very close look at that internal shift-linkage I mentioned. Look for evidence of metal-on-metal rubbing against the pan itself in the area of the dent. Also check for any deformation of the metal tabs that guide and support the transmission end of the shift cable to it’s mechanical connection point as well as the cable end condition.

One last thing, the 700r ATF pan didn’t come with a drain plug. Recommend installing one low on the rear face of the tranny pan for future use. It will come in handy one day...



Mike in PA

1663710468671.png
 
Joined
Jul 30, 2019
Messages
26
Location
So Cal
Behind the dented area on your 700r pan is the transmissions internal mechanical shift-linkage assembly. Unlike the TH350, there is not much room right there to gain the necessary clearance for the front output flange so the dent doesn’t need to be substantial. IIRC and from personal experience, the shift cable will bind if the dent is too deep. Does yours shift ‘smoothly’ or feel like there’s binding??

In the attached photo (700r), the lower rt hand corner of the valve body shows a sleeved, spring-like fixture extending forward. This is typically where the shift cable will bind with overzealous ‘denting’ of the pan.

I’m assuming you’ll be replacing the pan and gasket sometime in the near future to fix the leak? When you do, take a very close look at that internal shift-linkage I mentioned. Look for evidence of metal-on-metal rubbing against the pan itself in the area of the dent. Also check for any deformation of the metal tabs that guide and support the transmission end of the shift cable to it’s mechanical connection point as well as the cable end condition.

One last thing, the 700r ATF pan didn’t come with a drain plug. Recommend installing one low on the rear face of the tranny pan for future use. It will come in handy one day...



Mike in PA

It does take a little effort to move the shifter between gears, but I thought that was normal. It's the only 700R4 I've owned. Will certainly take a careful look at the areas you mentioned for the internal shift-linkage.

It doesn't kickdown, but I assumed that was due to the kickdown cable not being adjusted correctly. The 700R4 is supposed to be very sensitive to adjustment, so I didn't want to mess with it. I don't mind manually kicking it down.

Yes, a new pan and gasket are coming soon. The lack of a drain plug is sure to be a pain. I'll look into adding one.

Thanks for the info and pic!
Jon
 

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