cummins 12 valve swap help me

[Tango]

Not sayin' it's a piece-o-cake, but building a doghouse can be done.


Below is mine which now has the firewall where the old dash used to be (back about 20").



The base and sealing surfaces...



...and the actual doghouse (cover).

[randydupree]

i thought the pusher bus was air brakes?
your going to convert the bus to air brakes too?
and your going to narrow the front axle?
Like,cut it and weld it?
Please post what roads you will be driving on,so i can make sure i'm not near you.

[Elliot Naess]

Where do you live, SpiritJohn? I would be interested in an undamaged BB rear bumper.

[spiritjohn]

I'm in grants pass Oregon for both of you

Here is my thinking on this bus. The rear end I have is from 1953 and I do not think it will handle the Cummins well or at all. That being said it needs to go. If I can use the rear end of the bluebird I now either need to convert the brakes to juice brakes on it or keep the air brakes. Keeping the air brakes I now have to switch the front brakes to air brakes to match.

I am unsure of what it takes or if it is even possible to convert air brakes to juice brakes or vice versa so to me it just seems simpler to take what I already have which is the complete air brake setup of the bluebird. If it is a better option for me to replace all my juice brakes by buying all the parts one at a time and buy a Dana 80 or something then doing the air brakes then let me know that's why I made this post.

My thinking on shortening the front axle is that it is simply much wider than what I have. I know it's a crackpot idea but i am not the first,

https://www.jalopyjournal.com/forum/threads/tech-shortening-an-i-beam-axle.168603/

am unsure of the gawr of my 1953 front axle but am willing to bet an altered one off the bluebird is still stronger than metal that is almost 70 years old.

[Ronnie]

I like the idea of a Dana 80, and get the complete braking system from the donor truck. This is keeping in the same weight catagory as your bus, and just seems to be a better fit.

As far as cutting the front axle, are you an expert welder? and can properly heat treat the axle when done? If so this can be done, however it is not advised for most because a mistake can be deadly. Will you magnaflux the welds?

I am curious as to what the ring gear size is on the 53 chevy axle. It may well be as large as the Dana 80. Also axle shaft size and spline count.

[spiritjohn]

I am trying to figure out what my rear end is unsure of the ratio( new to this) but have found these numbers on my ring gear and axle

[spiritjohn]

Numbers are 3652522 6 37 gm 8 53 on ring gear
19 on axle. Have not pulled axles out yet or counted pinion gear.

[magnakansas]

The 2005 ford axle I used is wider than the 1954 ford bus body work. I found fenders that were wider and covered the wheel.

so find fenders from a bigger truck- almost semi sized and use them instead of cutting down the front axle.

My bus 1954 ford b600-- fenders I used 1956 f-800 they are about nine inches wider and go pretty much to the full 96" wide

william, and yes my is a poweredby a cummins 5.9 12valve

[Ronnie]

Originally Posted by magnakansas

The 2005 ford axle I used is wider than the 1954 ford bus body work. I found fenders that were wider and covered the wheel.

so find fenders from a bigger truck- almost semi sized and use them instead of cutting down the front axle.

My bus 1954 ford b600-- fenders I used 1956 f-800 they are about nine inches wider and go pretty much to the full 96" wide

william, and yes my is a poweredby a cummins 5.9 12valve

Dodge trucks did have at least two sizes of fenders available. If your front clip came off a one ton or less truck then you have the smaller fenders , and should be able to get larger ones. I had a set of big truck ones , gone now though. If you already have the larger ones with some careful sheet metal work you could add a spacer between the fender and nose piece. Done right it would not look out of place.

[Mekanic]

Originally Posted by spiritjohn

I am trying to figure out what my rear end is unsure of the ratio( new to this) but have found these numbers on my ring gear and axle

The absolute most accurate way to determine the gear ratio is to count the teeth on the ring gear, count the same on the pinion year and divide the ring gear number by the pinion number.

[Tango]

You are in luck. In the "olden days"...Chevrolet stamped the ring gear with the actual tooth count. That is what the "6 & 37" are in your first pic. That puts your ratio at 6.166 : 1.



Mighty low and maybe good for 45-50 mph tops.

[o1marc]

Originally Posted by Mekanic

The absolute most accurate way to determine the gear ratio is to count the teeth on the ring gear, count the same on the pinion year and divide the ring gear number by the pinion number.

Which is great if you have it apart, but not much help determining what it is while sitting in the driveway. Easiest way to determine is to jack up the back and turn the rear wheel and note how many revolutions it makes compared to the revolutions of the driveshaft.

[spiritjohn]

I did that but watched the ring gear more so than my tire. One rotation of the ring gear made the driveshaft turn 6 times

[spiritjohn]

If the 6.166:1 is my ratio and only lets me go 45 as a top speed, could I have it regeared in some way so I can go a bit faster than that?

[spiritjohn]

If I'm better off just buying a completely different rear end is there one I can just bolt on or will just about anything take some fabrication to fit

[Tango]

Depends on what is available for your axle. There may or may not be taller factory gears. There was NOT for my '46 so I swapped the whole rear end for a late model Dana 80. Stout and plenty of gearing options plus disk brakes. Post war trucks may have a few more choices but it will take a little homework to discover what factory stuff is out there. There are also some custom gear services that make wider ranges for some makes & models (depends on popularity).



Happy hunting and best of luck.


BTW...I was only guessing at the 45-50 mph. You need to run all your numbers through a gear calculator to determine what speed at what RPM.
I use the set below. The one at the very bottom of the page is excellent and you can play "what if" with any of the numbers.


http://www.csgnetwork.com/multirpmcalc.html

[Elliot Naess]

About the rear bumper of your Blue Bird, if it should be for sale.... Well, dang... I was in Medford two weeks ago! But I'm only a tad over 300 miles south of you. And I may visit my friends in Medford again this spring.

Interesting project you are working on!
Now... your old bus must have a stick shift? Since you are accustomed to that... might you want a stick shift with the new setup? If so, you can get stick transmissions with an overdrive ratio in the top gear.

[whiskey runner]

cool bus spiritjohn.. i will be watching your build for sure.. in my 1941-47 white bus i used a 70's international rear end i got out of a junk yard for 100.00.. i dont remember the exact gear ratio with 11R 22.5 tires it runs 65mph at 1900 rpm ..i usually get 14-16 mpg if i stay under 60mph which is very hard to do.. i have air brakes on my bus so not sure if you would want to go that route with yours

[Sleddgracer]

Whisky Runner - what product did you use to skin the exterior of you bus?

[spiritjohn]

I would sell that bumper, let me know when you're in southern oregon again