63 international

[63international]

hello all i have a 30ft 1963 international school bus with a 345 and a 6 speed allison it runns well but it is extremley slow excelerating and has a top speed of 55 on flat road my brother has a 79 ford f 800 with a industrial 429 and a allison 5 speed i was wantig to know if the 429 will bolt to my 6 speed and if it would be worth swaping out the 345 for the 429

[Ronnie]

the 345 can be a really nice engine, had one in my 1600 loadstar dump truck and could run 70 all day. So I have to wonder what condition is the engine in? Compression check? I would rebuild and add fuel injection long before putting a ford engine in. Speaking of which I do not know if they are interchangable. I have an allison service manual that came with my bus, will see if it says anything useful

[cadillackid]

ther bnig thing is the bell.. which allison are you running? an allison 1000? SAE bell? or an international bell? does the ford have the same bell on its allison?

there were version of the 345 fitted with flywheel adapters for SAE3 bells and allison AT545 transmissions.. im tryi9ng to remember if a 429 was ever used in a truck application with an SAE3 transmission like an AT545.. I know the 351's were.. reason thats important is if the allison on the ford was fitted via an SAE2 or SAE3 adapter to the ford, then youd be OK but if the allison was running a custom GM to ford adapter plate it might be tougher to get what you need to run your 6 speed on it..


you also have to look at how you can fit a 429 into your bus frame.. will the engine line up in such a way you can drill and bolt motor mounts to the frame?

-Christopher

[Ronnie]

Mine is a MT42 Allison, with an SAE2 bell housing. If his is original that is also what he should have. The 1000 series are much newer trans.

[cadillackid]

this is cool stuff.. my bad, I was thiunking someone had swapped in a modern transmission as is somewhat common these days in classic trucks..

I learned something new - the OLD MT series transmissions.. cool stuff.. looking at the ratios these things could pull a Train in first gear!! but still only 1:1 in top gear..

-Christopher

[Ronnie]

I have always prefered 1:1 in top gear, and then gear the rear for the road speed you want. The overdrive in my Dodge truck has been nothing but trouble, and overdrive in the auxilary now has two teeth broken off. Just my thoughts....

[cadillackid]

overdrive in my opinion was an easy way for transmission makers to keep basically the same design and many of the same parts and add gearing to a transmission..

in effect im totally with you on the idea of being properly geared in the rear, having 5 underdrive hgears and a 6 at 1:1, that design keeps driveshaft RPM;s lower, still allows for 6 ranges of forward gears for proper acceleration etc..

but manufacturers wanted cheap.. so if they could take a Turbo 350 transmission or a C6, and simply add a gear.. then they still share parts with the predecessor that was still made.. (TH-350 / 700-R4), ( C6 / C6-4AOD), etc... and being allison ended up being placed in a lot of medium duty applications, things spilled over there as well in the later years,.

now that I have read about these early 6 speed MT's, i wonder now how we arrived at the current state of affairs with 3 underdrive, 1 1:1, and 2 overdrive gears in the modern allisons..
-Christopher