Caveman tech - building a bellhousing for a flathead cadillac

Thanks guys...

While it woulda been nice to use less pieces and heat/brake-bend that plate,
it easier to get it more precise with the template-cut-weld method,
less grinding to fit this way.
TP

 

That's quite an undertaking. How are you keeping everything square and true?e
Getting the trans mount plate square to the engine and having the input shaft on the trans exactly centered in the end of the crankshaft has to be a challange.

I could visualize a few of the guys milling the plates out with their Bridgeports but that is unreal.

 

Travis, you always send chills up my spine. But I gotta hand it to ya, YOU THE MAN. We made something like that, but with aluminum and a big lathe.--TV

 

This is some good shit CHAVES! keep up the good work. See you soon.

 

that's the caveman part!

really though Zibo, i applaud your effort to make a bellhousing, but you really should have farmed at least a little bit out to a machine shop. you stand a real good chance of some driveline vibrations, or clutch chatter. the tranny and engine should be lined up within a few thousandths of an inch. that is possible with a homemade bell, but not really the way you are making it. being it is all torch cut and ground, there is nothing machined to come off of for dialing in the crank. the very minimum should be a nice round machined hole for the tranny to register in, with this hole true, you can fab up the bellhousing, and tweak it in using offset dowels to adjust it(or drill new dowel holes), and run an indicator mounted on the crank or flywheel around the hole in the bell. an even better option would be to leave the hole small, fab it all up and have a machine shop put the hole in based on the dowel pin locations, they could get the measurements off the block itself(preferred) or a stock bellhousing. the faces should really be flycut too, to ensure they are parallel to each other. when all is said and done, you will be very lucky if after all the welding the alignment ends up anywhere near where you think it will.

 

While I'm sure that the alignment concerns are well founded, why not wait until he's done and tried it out, you never know, the sky may not be falling after all.....

 

I'd recommend attaching a dial indicator to the engine's crankshaft and check the runout of the pilot diameter and trans mounting surface... before, during, and after the welding.

Maybe it is too late, but if I were in your shoes I would have made the trans mounting plate piece of the bellhousing a bit too small and then ground its diameter and face according to what the dial indicator told me.

Too much runout will cause the clutch to chatter as well as problems with the pilot bearing, trans input bearing, and clutch disc. If the runout were really bad, it could break the trans input shaft or tear the hub out of the clutch disc.

If you keep the runout down to acceptable levels (0.005" or less), your bellhousing will work perfectly fine. You can achieve that without going to a machine shop. I don't know if it will contain a clutch explosion, but that Cad engine won't buzz that high anyways. Excellent tech - who needs an adapter plate or kit???

 

Thanks for the machinist tips!

We do have a fake bridgeport to flycut? front and back, after everythings all welded up.

That tranny hole is so tight that when the tranny is inserted it makes a popping sound.
Its doesn't slide around even without the bolts.

There is a bearing in the crankshaft,
it aligns the input shaft.
Some engines have a bronze bushing which get a little sloppy,
but this one is an actual bearing.

The input shaft alignment is based on the slop of this bearing,
and in the line up "phase" I tried to shim the tranny up near the base plate
using something like a dial indicator to measure,
(basically had a magnetic pointer and feeler gauges)
and it wouldn't budge in there enough to be significantly measurable, esp. not 005.

Another thing I used was the throwout bearing and pressure plate arms to center everything.
Yeah this is relying on the circularness of those old arms,
but what i'd do is rotate the flywheel around and measure each arm (3) at different places.
Yeah the throwout bearing slips on that input shaft cover,
which has a little slop, but its very little,
and my thinking was if it was designed in the system then that was my allowable error.
even then there's no way its close to oo5 inbetween the bearing and the shaft cover.

Nothing was rushed really.

The main concern after all that was really the angles of the block/flywheel/tranny.

So when welding it will go in little inch sections symmetrical to the piece.

Hopefully it'll all work!

Thanks guys...

TP

 

UNBELIEVABLE! AMAZING! I'm sure any adjustments with alignment can be done after this piece is completed. That's some cutting/work table there. I'd never tackle anything this complicated; hat's off to you. But, the transmission is the old MUNCIE/overdrive unit, a Saginaw would be a bit stronger and be full syncro and came online around 1966. Nice work! Butch/56sedandelivery.

 

This is a great post. It's pretty amazing what you can build if you just dive in and start building it. I'm enjoying reading all this.

It seems like some things might get tweaked a hair out of alignment when it's done after doing all the welding (from shrinkage of the welds), but you could probably use a mill or a surface grinder or something to get the front and the back surfaces of the adapter perfectly parallel again, and use a rat tail file to slot the holes if they need adjustment to get the trans and crankshaft centerlines perfectly aligned.

If you need some alignment pins once you're sure everything lines up perfectly, I guess they go in last?

Cool project, man!

 

Very nice. I'm looking forward to more updates.

 

Love the can do attitude. this is why my truck sits in the garage, I cant stay off this site...Great work,

 

The drive you have to pull this off is amazing. I agree that alot of this adapter build could be farmed out or made with precision equipment, but isn't that what hot rodding is all about. It's amazing what can be done with hand tools if you put enough effort into it.

 

This is a cool post. I had Pat at Wilcap make me a custom adaptor for my setup, but I like the raw, sweat and guts fab of this. If I had the time and skills, I would do it your way too. I wouldn't worry too much about the alignment stuff at this point. Sounds like you are considering it enough and am sure it can be tuned later as needed. Good luck with the finishing. I am going to subscribe to this thread and keep an eye out for the finish.

 

If you're using the input shaft of the transmission to do all the aligning, I was thinking that it might be a good idea to put a dial indicator out near the end of the input shaft and turn the shaft and see if it turns true. It would be a shame to get it all aligned right and then find out that the input shaft of that transmission got bent somehow by someone dropping it off a forklift or something.

 

You don't need a mill to get the bell housing square and true. The way you have set it up so far will provide a really good start to aligning it ( the hard way )
If you setup a dial indicator to turn with the input shaft, and measure against the flywheel face ( at the largest diameter you can swing ) you will be able to check for parallel as you turn the shaft. Just use a grinder to remove the excess metal from the gearbox mounting face, a feeler gauge will give you a good idea of how much. Do this before you check for centre position. The centre position will change when you adjust parallel.
If you then setup a dial indicator on the end of the crankshaft to measure against the input shaft or the slide for the throwout bearing as you turn the crank, you can measure the offset and correct it by filing holes or offset dowels.

Its slow and fiddly, but it works as well as any other method.

 

well, mr. self appointed hamb post police, because i'm not trying to put down the great effort zibo has so far put into this, i'm trying to ensure it gets done to completion, it's called constructive criticism. i'm a machinist and i'll feel free to offer advice to farbricators who attempt jobs that should be done by a machinist when i feel like it. just as i welcome advice from welders when i try to glue parts together. after it is done is too late for help in either case.

you HAVE a mill available? why not use it to make the holes? i understand the hard way when you have no access to better tools, but you have the better tool already. or do you feel it's too worn to to be accurate?

good luck, and i hope it works for you! i'll be watching.

right, but hard to do with a bellhousing covering the flywheel and input shaft, etc. i suppose zibo could cut access holes in the bell to see into it. which all things considered, wouldn't be a half bad idea. the issue is not so much being able to achieve the required accuracy using "caveman" methods, it's actually being able to measure it to make adjustments. it would be possible to set up an inidcator up to read off the crank flange without the flywheel installed. it wouldn't be as accurate, but better than nothing. it'd take a bit of work though with mirrors to be able to read the indicator inside the bellhousing, so some holes would still be helpful.

 

You mean we got to wait untill the 15th to get the final installemnt?? Damn!

I wish I still had the piss-n-vinegar to do stuff like this. Personally I would have fab'ed it as a motor plate to eliminate the sag issues. Also, I'd be putting a hydraulid TO into it... But that's just me, and it may not fit the needs of your project.

Whatever alignment issues you *might* have can be solved on a milling machine after it's completed.

Looks great!

 

Exactly ! What a pessimist! This is amazing!

 

Great work. I love the caveman approach.

I had to dial indicate the bell housing on my Studebaker. It's not difficult.








Once you get the hole aligned with the crank center line then you drill a hole in the flange and block for alignment pins. I drilled the hole slightly smaller than the pin and used a precision reamer to size it. After the pins are installed you can remove and replace the bell housing without having to realign it every time.

I had trouble with clutch chatter when I bought the truck. The Stude guys said that not having the bell housing aligned properly could cause this. It doesn't chatter any more with the new bell housing using the same clutch.

Keep up the good work.

 

Good pics, Tommy.
Zibo - great work, can't wait until the 15th.
Mart.

 

yeah, no kidding!

this is one of the best DIY tech posts I've seen on the HAMB. Hardly cave-man at all.

Someone else stated this is a job that should be done by a machinist. I disagree. Not everything needs to be taken out to the third decimal point.

When I worked for a Mopar magazine, the editor at one of the competing magazines was known for harping about dialing in the bellhousing, and ran a tech article on it seemingly twice a year. When you hear that enough, you start to think "well damn, I can't just stab the input shaft in the hole! I've got to get a set of dial indicators, a magnetic base, machined shims and washers, and I have to blueprint this sucker!"

Except for this one fact: they weren't blueprinting the bellhousing on LS6 Chevelles and Hemi 'Cudas as they went down the assembly line. They stabbed the trans through the hole on the bellhousing and ran the four bolts up snug. And those transmissions survived just fine in the hands of average enthusiasts beating on their cars at the stop-lights on Friday and Saturday night, and every now and again at the drag strip. They don't break out the gauges in the service bays at the local dealership either.

Now obviously you need to be fairly close, but you don't need it dead-nuts on unless you're racing. From the way it looks to me, I'd say you're doing a pretty damn good job, and once you're done, if it needs ANYTHING at all, a little can be shaved off the mounting face to make it all perfectly square...but I don't think you're going to need it. Hell, take it to an engine shop and have them put it in the decking machine. All you need is for it to be square on the block and square on the trans face.

If it were me, I'd go with a bronze bushing rather than the roller. I think the bronze will be a tad more forgiving if there is very slight misalignment. I've had two bad experiences with roller pilot bearings, so I'm biased.

Nice job, and I'll be watching this one! It's giving me some GREAT ideas for making a safer bellhousing for behind the 322 Nailhead if I build a PanAm car. Wouldn't pass NHRA tech, but it'd keep shrapnel contained a helluva lot better than the stock cast piece or an aluminum adapter.

-Brad

 

Thanks alot for all the great replies guys,
they ALL really help keep up the momentum.
I wish I had time to reply to all individually,
but just know that all comments/suggestions/replies/etc. are greatly appreciated!

(however)
Tommy that is a great picture of the dial indicator measurement rig.
When its all together and double welded,
That will help set the dowel position,
probably will use a sturdy bendable pointer though instead to keep the caveman theme
Thanks!

Ray-we've got a tight mill but don't have one of those rotating tables!
My brother is the machine-tool junkie.
I'm happy with a grinder! (and some dave clark ear protectors)

And Brad i'm with ya on the bronze bushing vs roller bearing.
The flathead/OD tranny in my RPU has a bronze bushing,
and since there's so much sag in the stock stamped steel bellhousing,
there's no way a bearing would last.

And as to stock bellhousings not being perfect,
this is the one that was in the RPU that I replaced!
There is seriously a 3/16" bow in it,
thats what the angle and bar thickness underneath!
Yeah bolting it up straightens it out but still.

Another thing...

I had planned on needing the bellhousing to double as the rear engine/tranny mount.
(I thought it was a saginaw but guess its an early muncie?)
The OD unit DID NOT have a rear tranny mount.

After studying the frame area, it would be difficult to have bellhousing mounts,
AND room for a sidemounted clutch arm, easily anyway.
So the idea was to make a vertical plate to attach the rear of the tranny.

Well I pulled another one down to make a template,
and lo and behold whats there...

A tranny mount!

I'm gathering the RICH version is for the 6 cylinders, (embossed in back)
and the RICK version is for v8s.


And here's the " do it yourself caveman bellhousing kit" templates!

I'll update progress shots soon...

Thanks alot guys!

TP

 

Man, that bell is f'ing cool. Congrats again.

I was at a tech school that has a great motorsports program, and one of the tricks NASCAR teams do for bellhousing dowel alignment is to bore out the holes in the bell that slip over the dowels in the block, so they're way oversized. They they square everything up side-to-side/top-to-bottom with a dial indicator, lay a couple of washers over the dowels, on top of the bellhousing flange, and weld them to the flange. This positively and permanently locates the bellhousings on four of the six planes (side/side, up/down). The trans can sag or be raised too, which is another plane--that dimension is corrected with shims between the bellhousing and the block. I don't know how they figure that one.
With the method I just described, the bellhousing is permanently matched to the engine block, until you cut the washers off.
It's quick, and a lot easier than the offset dowels you can buy. And a whole lot cheaper, too.

-Brad

 

I love simple and elegant tricks like that.

 

I think the washer trick has been around since the first lakewood scattershield was installed - thats how we always did them.

 

Please note: A certain model of late Ford flathead bellhousings have a slant on the bottom half of the front mounting face. If you look at the corresponding bottom cover/starter plate, you can obviously see the angle there. DON'T go bending the flange straight, you may have a part that's supposed to be crooked.

 

yeah on that stock ford one the flywheel is goes outside of the bottom of the bellhousing,
like the sag was engineered into the design.
This type really wears out the bushing quick.
TP

 

We nicknamed it the turtle...

lotsa time between the welds, little 2" runs.


This 1/4" plate welds so nice.

The bigger gaps have a couple passes...

TP