Technical Caveman tech - building a bellhousing for a flathead cadillac

Hi guys.
I've been peckin away on this part of another project for a while.
And figured would throw some of these pics on here,
maybe it will help people to tackle something similar, or teach people what not to do...
Usually I like to post when its done, but here it goes anyway.
(Some of you have seen this already so pardon the duplo...)

So got this '41 caddy in a trade,
and it had been sitting for 2 years and finally found the perfect project for it.

It came with a stock sideshifter tranny that made the whole chelada about 6ft long, serious.
I wouldn't have minded it but I'd really like an OverDrive tranny so decided on a Saginaw 3spd OD.
Yeah they're an older version but this engine is torky enough to pull through the gears,
and I have a couple if one blows up.

The first part was making a template for the tranny.
The circle was about 4 3/4 " and this was perfect.
I've found galvanized sheetmetal is one of the best template makers.


a pick hammer found the holes...

and a little trimming an almost perfect template.

Since we have alot of scrap at the shop, decided 3/8" piece for the ends.

and some really rough torch work.
I didn't want to over cut it...

After a couple minutes of grinding...

kept on using the template to spray the area to be ground out.

would use the "rub the paint off" method to find the parts out of round.

Than when the hole fit the tranny,
eyeballed the center punch to the bolt-holes...

and drilled a small guide hole.

Than cleaned up the outside with the circle sander.

TP

 

Thats cool brother!

Invest in a set of drill bushings for "finding them holes", will save you a lot of time, and frustration trying to keep it in place when "hammer locating" the holes.

Looks damn good though!

 

The engine side was more difficult.
Here's what we got to start with.

It is an octagonal engine, with a round flywheel.
I hadn't really looked as much at the rear, so any ideas I'd been sleeping on were kinda useless.
The flywheel goes outside of the block.
The STOCK bellhousing is a TOP HALF bellhousing.
using a large bottom pan to cover up the flywheel.
At first the idea was to copy that,
but it just didn't as rigid, especially since the engine is so heavy,
engine to tranny sag is an issue.

Another issue is the starter takes up a huge section of the passenger side.
For some reason there are no bottom threaded bolts either,
so the whole thing rests on those 4 top bolts!

The other thing I didn't realize is the saginaw has no tranny mounts.
The bellhousing will also need to double as the rear eng/tranny mount.
(The stock caddy has a rear mount though)
So decided as obvious by the multiple templates needed,
to make a full circle bellhousing.


The templates were only half used though.
After alot of blank stares,
figured out the smartest way was to make a circle as big as the flywheel, about 16",
than another circle 1 1/4" bigger,
And use the templates to mark the areas that went outside of this minimum circle,
and add enough flab for the starter.

After some much better torchwork, whittled it out...

Once the ring was ground a little closer to fit,
did the center punch trick again and popped some holes...


Now it was time I thought to mock it all up...
TP

 

Dang it I gotta go be back in a little bit...
TP

 

I'll be interested in seeing this. It's nice to see someone go for it, when people would tell you it can't be done! Nice to see a low tech approach.
Thanks
Alden

 

Nice work Zibo keep it coming.
Our Cadillac Tech stuff is building up real good now.

 

this is nice to see. will be referring to this when it's time to get my flat caddy bolted to something.

 

Whoops excuse the delay there,
these posts take a little time and got some free time to work at the shop.

Anyway,
using the circle cut out,
made a jig to make an extension.

I had imagined using flat plate, and bending it in wide strips,
but the circular problem mentioned before changed that.

So me and no-glove friend Pigpen (luke) started the torch-work.

if you notice his gloves are on that burnt piece of paper on the left...

Fortunately no burns though.

After alot of heavy duty heat and dolly work,
got the ring into a resemblence of a circle...

It actually sprung in a little, not out.

and tacked it on to the mounted base.
Of course the first time it was too tight,
but the second time worked fine.

Than removed it to tack the inside a little.


I'd hoped to be able to begin joining the two pieces,
but there were a couple more important steps inbetween,
First was adding 2 bottom threaded holes in the block,
and figured 2 set studs? would be good too.

The difficult step is the starter location.
It is fixed (no adjustment) and without the original bellhousing for a template,
is tricky for this caveman...

TP

 

i take it you dont have access to anything as fancy as a brake press? then you could form the can out of one piece of plate (with a hell of a bunch of templates and patience)
this thread has me hankering for hitting something with a really big hammer.

 

Thanks for all your post

 

Nice work, I want to see more.

 

thanks guys...
Kevin - yep, but don't tell anyone!

OK so the starter.
First figured i'd better attach the flywheel a little better.
The flywheel is weird,
it is a solid steel flywheel, attached to a flex-plate like thing made of copper,
that is sandwiched between two pieces of steel.

It wasn't on securely as it was removed to weld the inside of the new bell.

This is serious caveman here.
If you look back at the block picture,
there is a big cutout where the starter should go.
The starter sits somewhere in that arc.

So first made a template of the arc,
and then made a template of the circle on the starters base, that goes into the plate.

Then moved them around til they looked like they'd be right

of course ran out of white paint so used the worst possible color, the color of fire...
so of course the hole was too small, but better small than too big...

This is called a 'donkey dick' a well used one anyway...

after a little grinding the hole looked round,

and using the same paint and rub method,
the starter plopped in as perfect as a grinder could get, like magic.

When the bell was placed back on,
a tooth check was in order.

and according to some trusted individuals,
somewhere between a paper clip or 2 paper clips should be in the crown and base,
which is about right where it sat, even though it looks tight cause of the shadow.
I clamped the starter on and zipped the starter with a battery,
and it didn't make any chirping noises, and the gear went in and out,
but I decided to hold off on the permanent tapped holes in the base,
only center punched where they should be, just in case.


So since that headache was mostly done,
made up the last part of the ring.

and zapped it all in place.

rechecked the starter/flywheel teeth and it didn't seem to move.

Anyway that was a good night.

TP

 

Man these posts take long,
anyway here's a lunchtime update...

Attached the pressureplate, and threaded the new block holes, finishwelded the main ring.

Also threaded the tranny base plate holes, exciting stuff I forgot to take pictures of...

Started the mock up, this took a couple tries since I forgot the throwout bearing etc.
But basically centered it with the flywheel bearing,
then degree wheeled it to the flywheel and tranny plate, and side to side,
and took as many measurements as possible to keep it as parallel to the full circle.
The input shaft is about 5/8" shorter than the caddy,
but there's just enough room for a couple variations of the clutch arm.
TP

 

dude when i saw your teaser shot i was intrigued. now i'm amazed. i thought i was caveman. i dont think ive found the cave yet or at least not fire

 

Hmmm, nice

I'm probably gunna do the same myself only hemi/hydro and i have full access to a waterjet and fab shop

 

great tech post , thats one burly welding table , looks like youd need a derek to move it keep posting as you build very interesting stuff

 

WOW- Great post!! I wish I could add more!

 

keep it coming.... nice stuff right here...

 

shweeet! You should have saved this one for tech week....great project!

 

looks great
lookin forward to the next segment ​

 

Its called an "acorn" table. Or so i've heard anyway.
These were at an old shipyard in San Diego, used since WWII probably.
They're great for bending stuff, hammering stuff, with heat.
I've made some all-thread clamps that hold things on for past projects,
so they've become more and more useable.

I guess there're also these wedge things that can go in the holes,
for pounding, i'll get some pics later.
(we used a crane truck and forklift to move em, heavy fokkers)

Will get some more updates soon...

TP

 

The sticky post above said tech starts on the dec 15th,
but it just has to end after the 15th.
(hmm I better print that out for proof huh!..)
Anyway I've got alot more time needed to finish it so its shouldn't be an issue...
I think finishing it before January 15th is the issue!
TP

 

damn you're ambitious!
ever think about using an outdated scattershield for some of it?
it AIN'T gonna pass sfi stuff anyway...


i vote this gets included in tech week!!!!

 

I am in the process of installing a 48 Cad flathead in a 40 packard. Weird combo but thats what the guy wants.

We went the easy route and bought the adapter from Bentsen. Fits like a glove but it was $800.

 

Yeah I considered it trying to adapt another bellhousing,
but the saginaw based ones are either cast aluminum or iron,
which is basically useless for this project.

The Bentsen adapter huh, cool that they make one for the oddball tranny.
kinda trying to save that $800 even if its only $2/hr after torch gas, discs, materials etc....

Well we have a ton of zinc chromated coated 1/4" plate,
which is nasty to cut, torch, grind and weld,
but its good stuff.


This is the start...



TP

Tomslik - Thanks for the entry vote!

 

Dont you just love guys with no fear...
keep at it buddy.

 

......and brains, tools, and skills

 

Anything but caveman! Good work so far!

 

Interesting