How strong is an old Ford ******

Robert Dip

Robert Dip

Senior Member
Being teenagers in the mid 60’s, we had a lot of old Ford Hot Rods…some pretty much stock except for hydraulic brakes and 8.20 x 15 tires in the rear, done up interiors and so on. Ran a ’35 for quite some time with a 59AB and a top loader with ’47 gear set. Not much problem there, 30,000 miles only cost one ******….don’t know why I broke that one. But then, along came the 283 2 barrel with approx 180 HP. This swap became pretty standard at the time, but, the old Ford top loaders became the nightmare. They would last about two weeks and they would knock off the teeth just accelerating. Well, today, a lot of us have gone full circle, and we are back to the old Ford trannies….because that is what we want. Question is, a 100 HP 59AB with a cam, 4" crank, carbs, headers, etc…..might come close to that then monster 283……are our old Ford trannies going to hold up? Ok, I know, we are gentler with the cars since most of us are so much older, but, it still bothers me a lot. I also have the 25T L-Z gear sets, as I believed that with V12’s, the gears would be also stronger, but it does not appear to be so….maybe I was not installing new bearings or checking the tolerances back then…..What are your experiences now & then??? Thks Robert
 
These old trans are no stronger today,buying a couple of used trans with bad teeth,I had that problem when i was a kid.They new me and all the junk yards looking for 2nd gear and a matching cluster gear.Bad memeries I went with a c4 auto trans.
Never miss a shift and much quicker.Just don,t pop the clutch and you will be ok.
 
The old Ford trans did a good job if maintained and not all worn out. The main problem was abuse. Jack rabbit starts, poping the clutch to get some second gear rubber is when they usually let go. The junk yards always tried to keep a ready supply and they were plentiful and cheap. Don't you remember spinning the tires on gravel and then sliding onto the road to maximize the burnout. The old hard rubber really had a screech to it back then. Treat them for what they are and they will do fine.
 
Back in the early 60's i ran an Olds, 11" PP, 10 1'2" disc, thru a 39 ****** into a 40 merc r/end in a stock bodied 32. Weak link with that combo was axle key. Late 60's had a 40 coupe, olds thru a 39, no problems. Use your head.
Paul in CT
 
Had a nice rebuilt trans in my 39 Sedan Delivery with 59AB/Merc crank. Was half way to Back to the 50s in Minneapolis. Shifted into second going up an acceleration ramp. Bang, the teeth broke on the input (large) gear on the cluster. No fault of shifting there. Got to Minneapolis in high slipping the clutch and stroling through stop signs.

Replaced cluster. Stuff happens even with new cars. Happy V-8ing
 
RD,
Hmmm a sbc with a 2 brl and 160 hp is more engine than a normal
Flathead built with street hop up goodies. The sbc has way more twist
but yuck...not for me.
BUT
Back to running a '39 trans in back of a warmed up Flathead....no problem
if you promise yourself no speed shifts and burnouts. The trans will survive
a few of these 'kid moves' but you'll pay eventually. The second gear thing
goes back to the junction of the input and output portions of the trans
which are 'tied' together ,sort of ,with a cheesy 3/4 roller bearing...lots of
flex here. When 2nd bushing and end thrust washers are worn out the
gear actually bangs against the rear washer as the gear fights to climb out
of mesh,not real healthy.
I'm running a true 130 hp stroker '49 Merc in my '41 1/2 ton...so far so
good........the '39 trans has been real good but then again no ' kid
moves'
I'm going to drag this out one more paragraph......I build a
lot of early transmissions but I can tell you ,at the risk of killing some
business ,that you can absolutely do no better than a T 5 trans from
an S10 behind your Flat motor. The frame under my '41 was so perfect
I could not bring myself to modify it and that's the only reason I'm not
running a T5. Drive an old Ford equipped thusly....it's an eye opener.
Charlie ny
 
Listen to Charlie!
The whole thing becomes a flexi flyer if that mid shaft roller area is shot, and of sourse all other bearings affect things too. Endplay is the start of SERIOUS violence with helical gears, and is often ignored.
I have an article from a circa 1960 magazine on Chassis Engineering setting up an early trans for use in a dragster (top two gears only). Close tolerance bearings, endplay eliminated, and as with 9" rears in modern drag cars the gears were re-tempered much softer than stock.
 
I know it is not a stock item but what about a later model all syncro 3 speed with a Jeep shifter? Shifter can be modified to look stock and the transmission is strong.
 
Charlie ny said:
RD,
Hmmm a sbc with a 2 brl and 160 hp is more engine than a normal
Flathead built with street hop up goodies. The sbc has way more twist
but yuck...not for me.
BUT
Back to running a '39 trans in back of a warmed up Flathead....no problem
if you promise yourself no speed shifts and burnouts. The trans will survive
a few of these 'kid moves' but you'll pay eventually. The second gear thing
goes back to the junction of the input and output portions of the trans
which are 'tied' together ,sort of ,with a cheesy 3/4 roller bearing...lots of
flex here. When 2nd bushing and end thrust washers are worn out the
gear actually bangs against the rear washer as the gear fights to climb out
of mesh,not real healthy.
I'm running a true 130 hp stroker '49 Merc in my '41 1/2 ton...so far so
good........the '39 trans has been real good but then again no ' kid
moves'
I'm going to drag this out one more paragraph......I build a
lot of early transmissions but I can tell you ,at the risk of killing some
business ,that you can absolutely do no better than a T 5 trans from
an S10 behind your Flat motor. The frame under my '41 was so perfect
I could not bring myself to modify it and that's the only reason I'm not
running a T5. Drive an old Ford equipped thusly....it's an eye opener.
Charlie ny
Click to expand...


Charlie:

Being you do this a living, I'm glad you mentioned that. Too much forward/aft lash caused by worn, incorrect thrust bearings or a grooved face on the thrust bearing surface of the trans. case is a big reason for blowing up gears in this old boxes.

As you mentioned, once the cluster starts to move around more than it should, it causes all sorts of bad things to start happening.

Thanks for posting.

Tim
 
bruce, i`d be interested in reading that article that you referred to, if you can post a copy of it.
thanx
 
Thanks Charlie ny....the interesting part is your comment on bearings and thrust washer play.....to a lot of the guys on more modern transmissions or T5, not going that route. I am keeping the cars using original Ford stuff in my era theme builds and can use all the help on making sure a good ****** rebuild using the best parts and keeping tight tolerances are part of the solving the broken gear problems. The projects I have are so original part oriented that even the tie rod ends have to have the Ford logo....my fun game. And yes, not driving the car with bad moves is definitely there, but you all know how it is....soup up a flathead and we have to see how well it behaves and accelerates. The ****** gear-crunching thing is always on my mind from the long ago past. I am sure over the many, many years, a lot of the guys have acquired info on how to make them run better and more reliable under a bit of acceleration stress. I also have quite a few trannys to rebuild, so input would be most welcomed…..Robert
 
I too am having the same thoughts! I want to keep the original closed driveshaft but am thinking about a new twist-----using a converted 55up
Chev transmission that is converted to the closed driveshaft. I have one in the shed that I used years ago. The only problem is using the side shifter shift mechanism. Years ago, Offy produced an aluminum box that took the Chev gears but used a top shifter from a late 30s GM transmission----It was called the "X Shifter".
 
I'll see if I can find article and someone tech enough to post it...an addendum, remember that a lot of the endplay in upper shaft can be...in the middle! You can kill the play at each end bearing and still have slop hiding there...you have to deal with total length.
The Chevy box is workable, but isn't really a significant upgrade. Weak, same endplay issues as Ford (I have some info on blueprinting those, too!), frequently blew even on stock class 265 cars. I have pics of an X shift with Ford torque tube adapter...article implied you could do about same thing with some combo of early pickup case and 55 gears.
There are torque tube conversions out there for the much better T5 and also a variety of toploader 3 and 4 speed trans.
 
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As Charley NY says , back lash can destroy a ****** pretty quick. Back in the day when the big Olds engines began breaking them we would put the input shaft and out put shafts in a lathe and measure the distance between the bearing snap rings. This is the length of the case and most cases streach during use. We'd then remove meterial from the rear of the case and to give .006". Then install the cluster as tight as possable. When the trans was assembled in this manner you couldn't turn the input shaft by7 hand. Now you had a trans that would stich around for a while. Probably forgot a few things but the ****** guys will pick up on it.
 
Hi all; I have a light weight 34 Jalopy circle tracker, and if the tires hook up real good, the trans will break. Stock eng 85 hp. This year I'm going to a modern trans period. Newc
 
I and several I knew used the 39 transmission back in the 50's.
We all used 25 tooth gears. We almost never broke one.
These were all light roadsters.
As others have said, everything inside needs to be tight. No worn parts.
You can shift as fast as you are capable but you MUST blip the throttle.
NO FULL POWER shifts.
The secret to long life of the 25's is the close ratio. There is less torque multiplication stress on the case and shafts.
I successfully used a 39 box for road racing for 2 years and used 1st gear
on tight corners. Just a matter of learning to shift like a crash box.
The whole thing here is "finesse".
They will take a lot of abuse if you know and observe the limitations.
 
I think it was Richard Lacy who said, when questioned about the strength of transmissions or rears, "It depends on whether the person driving is the person who pays for and makes the repairs."
 
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