Modifying 26 spline extension housing to 30 spline

[68BarracudaTT]

So I am looking to save some weight and money in my transmission build. I have 2 C-13386 extension housings (Aluminum overdrive 26 spline) and one C-99126 (Iron 1:1 30 spline). I would like to use my 30 spline main shaft with an aluminum extension housing (I'm going to use a 1:1 gearset). It looks to just be opening up the bearing and seal bores.

Has anyone modified a C-13386 to accept a 30 spline tail shaft bearing/seal? Has anyone measured a C-13212-2 or C-13305 (Aluminum 30 spline) vs. a C-13386 to see if the external dimensions are similar? I can get internal dimensions from the iron extension housing, but don't want to thin out a wall too much and risk breakage down the road.

Thanks for any and all help.

 

[weedburner]

I was faced with a similar dilemma for my cast iron Ford Toploader application, I like to save weight and money too!

I ended up machining my own bearing/seal housings and fabricating the rest of the tailhousing from sheet steel...

Bearing and sealhousings were machined from cold rolled steel round stock, the center tube is 2-1/2" dia x .065" tubing, the upper bracing is 14ga steel.

Made it easy for me to put the shifter bracket on the pass side, which allowed me to make a lighter shifter bracket. I wanted the shifter location to be high and above the output shaft, placing the short stick shifter in my console opening. I don't have a shifter installed picture for the Toploader, but it is similar to this shifter arrangement I made for a Saginaw...

My formerly all cast iron Toploader now weighs 91.4lbs full of oil with a slip yoke installed.

No problems at all, at this point the sheet steel Toploader tail has been in service for 10 years.

Grant

 

[68BarracudaTT]

I was faced with a similar dilemma for my cast iron Ford Toploader application, I like to save weight and money too!

I ended up machining my own bearing/seal housings and fabricating the rest of the tailhousing from sheet steel...

View attachment 1715982184

View attachment 1715982185

Bearing and sealhousings were machined from cold rolled steel round stock, the center tube is 2-1/2" dia x .065" tubing, the upper bracing is 14ga steel.

Made it easy for me to put the shifter bracket on the pass side, which allowed me to make a lighter shifter bracket. I wanted the shifter location to be high and above the output shaft, placing the short stick shifter in my console opening. I don't have a shifter installed picture for the Toploader, but it is similar to this shifter arrangement I made for a Saginaw...

View attachment 1715982188

My formerly all cast iron Toploader now weighs 91.4lbs full of oil with a slip yoke installed.

No problems at all, at this point the sheet steel Toploader tail has been in service for 10 years.

Grant

That is insane looking, I love it. I am just hoping to save a few bucks by modifying what I have; I don't think my fabrication skills are up to that level yet.

You didn't get any issues with binding by having a straight stroke of the shifter rods and an arc on the shifter pivots?

 

[DionR]

I was faced with a similar dilemma for my cast iron Ford Toploader application, I like to save weight and money too!

I ended up machining my own bearing/seal housings and fabricating the rest of the tailhousing from sheet steel...

View attachment 1715982184

View attachment 1715982185

Bearing and sealhousings were machined from cold rolled steel round stock, the center tube is 2-1/2" dia x .065" tubing, the upper bracing is 14ga steel.

Made it easy for me to put the shifter bracket on the pass side, which allowed me to make a lighter shifter bracket. I wanted the shifter location to be high and above the output shaft, placing the short stick shifter in my console opening. I don't have a shifter installed picture for the Toploader, but it is similar to this shifter arrangement I made for a Saginaw...

View attachment 1715982188

My formerly all cast iron Toploader now weighs 91.4lbs full of oil with a slip yoke installed.

No problems at all, at this point the sheet steel Toploader tail has been in service for 10 years.

Grant

That's insane. I like it!

 

[DionR]

So I am looking to save some weight and money in my transmission build. I have 2 C-13386 extension housings (Aluminum overdrive 26 spline) and one C-99126 (Iron 1:1 30 spline). I would like to use my 30 spline main shaft with an aluminum extension housing (I'm going to use a 1:1 gearset). It looks to just be opening up the bearing and seal bores.

Has anyone modified a C-13386 to accept a 30 spline tail shaft bearing/seal? Has anyone measured a C-13212-2 or C-13305 (Aluminum 30 spline) vs. a C-13386 to see if the external dimensions are similar? I can get internal dimensions from the iron extension housing, but don't want to thin out a wall too much and risk breakage down the road.

Thanks for any and all help.

Curious to hear how this goes. I don't have a trans accessible but I am sure someone does and could get you dimensions to compare.

 

[weedburner]

You didn't get any issues with binding by having a straight stroke of the shifter rods and an arc on the shifter pivots?

The parts that reach down to the shift levers have vertical slots, the shift levers themselves have threaded studs installed to engage the slots.

Grant

 

[66fs]

So I am looking to save some weight and money in my transmission build. I have 2 C-13386 extension housings (Aluminum overdrive 26 spline) and one C-99126 (Iron 1:1 30 spline). I would like to use my 30 spline main shaft with an aluminum extension housing (I'm going to use a 1:1 gearset). It looks to just be opening up the bearing and seal bores.

Has anyone modified a C-13386 to accept a 30 spline tail shaft bearing/seal? Has anyone measured a C-13212-2 or C-13305 (Aluminum 30 spline) vs. a C-13386 to see if the external dimensions are similar? I can get internal dimensions from the iron extension housing, but don't want to thin out a wall too much and risk breakage down the road.

Thanks for any and all help.

Not worth it. You can get aluminum tail housings, use them or just use the iron 30 spline housing. Not much weight savings in the tail housing. You would be better off selling what you don't want and buying what you do want and being done.

 

[68BarracudaTT]

I went ahead and cut my aluminum extension housing to the same dimensions as the iron 30 spline unit I had. It wasn’t that much, less than 0.25 on the diameters, so not much reduction in the wall thickness. I did have to cut the seal bore about 0.1 deeper, but it shouldn’t affect anything. The knee on the mill I have access to wouldn’t go far enough down to use a boring bar, so I had to circle interpolate the diameters. I will have to wait on the seal and bearing to make sure everything fits up ok, but if all works out I saved myself a couple hundred bucks.

 

[446acuda]

The tailshaft housing bushing for a 727 and 30 spline 3/4 speed are the same as a Ford C6 and other 31 spline Fords so the seal must also have the same I.D. So there are other seal possibilities if the stock mopar seal is a problem

 

[autoxcuda]

I have the same situation.

just need seal and bushing bored out

 

[68BarracudaTT]

The tailshaft housing bushing for a 727 and 30 spline 3/4 speed are the same as a Ford C6 and other 31 spline Fords so the seal must also have the same I.D. So there are other seal possibilities if the stock mopar seal is a problem

Thanks for the info, if the stock parts don’t fit up I’ll look at the Ford seals.

 

[68BarracudaTT]

I have the same situation.

just need seal and bushing bored out

View attachment 1715983986

View attachment 1715983987

View attachment 1715983988

View attachment 1715983989

It wasn’t too bad if you access to a mill, and a boring bar would have been ideal. Not sure about doing it on a lathe, you could probably center it on the bearing bore, but it might take a bit more time to fixture.

 

[chignikred]

Yes, this can be done. I've had it done, worked fine.