Confessions of a compulsive tinkerer.

Hi All,
Just a few thoughts on simple transmissions (light truck that I have garnered from observation, reading good answers on many forums including this one, and quite a few asprin!)
Came about through always having a soft spot for early ‘compound’ transmissions, Spicers 4X4’s, 5X3’s, 5X4’s,Mack quadruplex, triplex, duplex, Fuller, Brown-Lipe “joey” boxes etc.etc. These things in some cases, are getting harder and harder to lay your hands on all the time, and if you are lucky enough to get hold of one, it could cost you a King’s ransom, or you will have the devil’s own time even getting replacement parts for.
I had been tooling around for some time with the common old garden variety New Process NP435’s, used by just about every light truck manufacturer over the years. At one stage or another I have had about a half dozen here, couple of Ford, couple of Dodge, an International as well as the close ratio, all synchro Dodge NP445**. They are very easy to get hold of,(the NP435's! NP445's are getting extremely hard to locate) remarkably strong for their size (if a bit heavy, weight wise) still get parts reasonable easy (for Ford or Dodge anyway) and very simple to work on.
It wasn’t until my NP445** (all synchro close ratio) arrived from the states and I took the main lid off it and on closer inspection, worked out that they pulled a very simple manoeuvre to obtain the’close’ ratios whilst still utilising quite a lot of internals from the sister NP435. What they had done was simply changed the input shaft to main countershaft gear count from 17/43 in the 435 to 23/37 in the 445 but added an extra synchro ring to first gear. The boxes themselves are NOT interchangeable, the 445 having an extra inch added to the case to allow for the extra synchro ring and they also repositioned the reverse gear set up. The removable gears on the mainshaft as well as the tooth count on the corresponding tooth counts on the countershaft remained the same in both boxes It got me to thinking why couldn’t you take it a step further and make the ratio’s even closer? Hence all the seemingly odd questions on the HCVC forum. I had a look at the innards of a Spicer 7043 and they are so simply built, why couldn’t the principle be adapted? The 7043 I took the lid off was the 0.81-Direct-2.41 version (or thereabouts) where overdrive once engaged, the power was redirected back through the countershaft to the output shaft, a very simple idea and it must have worked, in their day there were thousands of these around and they would have done untold millions of miles!
I came across an internet posting by some bloke in the states who had applied for (and got) a US patent for his “compound transmission for light trucks”, virtually bolting two common NP435’s together using an adapter plate. Very detailed description of how he would go about it, he also said the same principle(s) could be adopted for Warner Gears T18/T98/T19 and even G.M’s SMH 420 and 465.
After going over his notes enough times to contract conjunctivitis, I thought why couldn’t his principles also be taken a step further? Instead of bolting two simple transmissions together with an adapter plate, why not leave the primary transmission alone and in the case of the Ford or Dodge that runs an intermediate tailshaft carrier and bearing, simple replace it with another transmission, albeit with a different ratio otherwise it would be pointless, you would simply end up with the same ratios. BUT, if the two transmissions had DIFFERENT ratios, you would have multiple speed transmissions, in other words, a “joey” box.
Working off a calculator and paper, without altering the actual ratios as can be seen from the example following, you can achieve a wide range of ‘steps’, The ratios in a NP445 are as follows, Ist-4.56:1, 2nd 2.28:1, 3rd 1.31:1. 4th gear simply locks the input shaft to the output shaft, 1.00:1) The ratios in the common NP435 (Inter, Ford, Dodge) are 1st-6.68:1, 2nd 3.34:1, 3rd-1.66:1 4th-1.00:1. So it can be seen that quite a spread of gears can be obtained.
First question? Why would you bother when there are so many 5 or even 6 speed light truck boxes available with or without overdrive? I cede the point, you can just about adapt any engine to any transmission if you are willing to tinker, like me.
Somewhere along the line, SOME machining will have to be done, if you haven’t got access to even a lathe, let alone some sort of milling machine, it could cost you BIG bucks! Do your sums FIRST!
I opted to go the route of keeping machining to a bare minimum by using up as many parts as I had here and designing a mid mounted “joey” box as described previously. I have a D5N 200 Dodge looks a likely candidate, straight six hemi (245), NP435 (which I may swap out for the NP445), they are at least interchangeable as a complete unit, although one box is an inch longer and one mounts from the sides of the bellhousing, the other from a crossmember at the output housing of the tranny, NOT insurmountable.
When it comes to the second, or what will become the ‘Auxilliary’ or ‘joey’ box, at this stage the only alteration would be the input shaft, (other than putting a spacer on the reverse idler shaft so reverse can't be selected, and blanking off the reverse lever position in the shift tower, no need to remove them and the reverse idler shaft would still be splash feeding the bearings and gears at the rear of the box) The rest of the transmission stays intact, EXCEPT in my case changing the output yoke, so I can utilise all my 1310 and 1350 yokes and universals, shafts etc. If ever it blows up, or something goes wrong, I can simply revert to the original tailshaft set up, (providing I don’t cut up the wrong ones!)
The input side of the “joey” needs some clarification. I removed the bellhousing and all accompanying clutch throwout gear (not needed). With a bare case (Dodge, because they are still easy to get and also inside the tailhouse extension, they run a substantial ball bearing, unlike Ford who use a bronze sleeve), The centre indexing hole in the front of the transmission case is bored out on a mill, to accept (in my case) a cast steel Dana 20 transfer case OUTPUT housing. These are quite robust, quite short and run hefty bearings and seals with the added benefit of the input shaft can be fully self contained and easily removed from the transmission. They were designed to run anything up to full size Jeep wagons and trucks, so will take a fair bit of power/torque. There appears plenty of meat around the indexing hole to mount the Dana 20 housing, by drilling and tapping the case the same way as bolts the original bearing retainer on, maybe even make it a bit stronger by adding another plate that goes over the Dana housing and relocates in the original bellhousing bolt position.
I am utilising an input shaft from a 281cu in International NP435 tranny I have here, simply because it has the same tooth count as the Ford and Dodge (but different indexing holes as well as different bearing retainers, but they will not be used, going into the Dana 20 housing) plus it is an inch and a quarter diameter shaft as opposed to Dodge one inch fine spline and Ford inch and a sixteenth coarse spline). After hunting around and numerous phone calls, finally found a machinist in Dandenong who thinks along the same lines as I, (anything is possible if you think hard and long enough about it!). Now I have all the correct bearings, seals yokes etc, it’s a matter of taking it all down to him and letting him have a look at shortening and resplining it. Had to blank off the speedo drive (would have run in reverse) with a simple bung after tapping it out to the correct thread. One thing I haven’t quite sorted out is either making or adapting some sort of oil slinger to ensure adequate lubrication in the new housing.
Second question? Is it worth the hassle? Unless you have got it in your head that it’s do-able, probably not when you will end up with the same direct drive. The Dana 60 diff in the Dodge is currently 4.10:1, can always either go to a different ratio, say 3.5 or 3.73:1 at a later date OR, play around with the ratios in the ‘auxilliary’ transmission, altering the input to countershaft gearing as described above. (it CAN be done, but a fair raft of machining involved, may prove impractical, maybe better to simply change diff ratios, (can always adjust the speedo with a correction box). Have a better spread of gears at least.
Third question? Is it worth the cost? Well, disregard the cost of the truck, would have bought it at the price I was offered it anyway. One Dodge gearbox cost me a bottle of Bundy, one Ford gearbox cost me a carton of VB stubbies and the Inter box cost me $50 because the bloke didn’t drink! Dearest item so far (without machining costs) has been for the bearings, seals and had to order in two universals at $60 each because they had to be the type to utilise differing size yokes. So far has cost in the vicinity , including the Bundy and carton of VB, about $450-500.
One other thing, the shift lever can be slung off the side of the Dodge auxiliary box, pre-drilled already and do the same as cab over Bedfords and many more used, have a yoke and cross tube made up and welded to a shortened gear lever. Got plenty of them! And, if I was really cunning, I’d have a male thread run down on the short bit of shaft sticking out of the housing. That way I could always have a bit of threaded female bar made up and screw the original stick back together, or simply weld the tube to the longer end.

The second part of the exercise is marrying an NP445 OR NP435 Dodge gearbox to a Ford 6/V8 bellhousing. Turned out to be relatively straightforward. Later model Dodges, (NOT the ones with the handbrake drum on the back of the transmission) have a set of “ears” cast into the front face of the box. Simply a matter of tapping the lower two ‘ears’ to 7/16” UNC and using dowels on the top two holes to reduce from 9/16” down to 7/16”. The bearing retainer housing has to have a skim taken off the circumference to fit the smaller Ford bellhousing. A Dodge 23 spline or Ford 10 spline or even an Inter input shaft (all the same tooth count, 17) can be swapped in and out, BUT you need the correct input shaft bearing housing as well as modifying the throwout bearing tube. I simply had a sleeve turned up to external Ford size, pressed it over the Dodge tube and used Loctite on it. Can’t go anywhere and that way, can swap Ford, Dodge backwards and forwards relatively easy, using the corresponding clutch plates, Ford or Dodge, input shafts and original bellhousings. Inter shaft is way too long for either Dodge or Ford bell.
The third part of the exercise is marrying the modified transmission (as in step two, NOT the auxiliary or ‘joey’ box!) to a Range Rover 200TDI 2.5 diesel. Again, this has been done many times with the old Land Rover 4’s and 6’s. Instead of big heaps of machining, I used the original Range Rover 9&1/2” pressure plate, 1971-1981 Valiant 9&1/2” clutch plate, had a sintered bronze bush turned up in a lathe to fit both the R/Rover crankshaft and the Dodge 23 spline input shaft. The only alteration there was have a longer female spline put into the Valiant clutch plate to guarantee full contact with the splines, again any half decent clutch bloke can do that.
The R/Rover has a very simple ring of bolts surrounding the crankshaft housing, gave the machinist a 500mm X 600mm X 10mm mild steel plate. Once he has found dead centre, simply machine out the guts (once the Ford bellhousing has been etched into the OUTSIDE of the ring of bolts, again using the previously marked dead centre) After guts of steel plate has been removed, either by laser, water jet or machined out, you simply remove, AFTER you have marked and drilled your Ford bellhousing to adapter plate holes, go around the outside and remove all excess material. Not rocket science! You don’t have to worry about starter motor mounting position, it’s in the crankshaft housing bolted to the back of the engine. And, the Ford bellhousing will give you a complete circle, Dodge although cast iron as well, only goes from about 8 o’clock to 4 o’clock.
By retaining the Ford throwout bearing plate, I simply had an extra long carrier made up on a lathe to suit the Ford sleeve. That way you can revert to all standard clutch parts if you ever want to put the box back behind a Ford. Don’t do what I did and misplaced the small retaining spring which positions the clutch throwout lever to the fulcrum! Had the devils own job getting a replacement, had to get one in from the states, cost $5 and $15 postage! One other thing. Ford and a lot of people who supply clutches and kits will tell you, you should be using a flat faced clutch throwout bearing. My clutch bloke said NO WAY! The correct bearing will have the raised lip, approx 1-1&1/2mm fitted to it. He showed me a few pressure plates that had the teeth almost worn through from using the incorrect bearing!
If your machinist is any good he will drill and put in your retaining dowels for you whilst he’s got it. The whole adapter is then surface ground, only needs a skim to ensure trueness, back to about 9mm or at a pinch, 8mm. TAKE any more and the input shaft tip will have to be ground back accordingly! The only other thing that needs doing before assembly is to drill out the rivets in the clutch throwout bearing fulcrum, slip in a spacer the SAME thickness as the adapter plate, reinstall the fulcrum with countersunk machine screws, make sure it doesn’t interfere with the back of the bellhousing to gearbox face and you can bolt it all together!
Now, what am I going to do with all these modifications? As said previously, have a D5N 200 Dodge in quite reasonable nick, could jump one way and drop the diesel plus either one of the boxes or even the two transmissions in it?
Also have a 1975 rare US postal Jeep (81” WB) way too short to drop anything in except maybe a 2.5 diesel with a close ratio box? Swap the Ford engine that’s currently in it (Postal) for the 245 HD Hemi Dodge?
Possibilities are endless.

Congratulations Dave ....... U got me in
U B the 1st full length post eye've ever read
dun normally like read n
but u sound like a man wiff a mission
trucks normally have joey boxes as to get the most power n speed to the ground by multiply n the ratios so there aint no huge rev drop B tween gears
R your boxes of the type th@ can B progressively shifted with no overlapp n ratios?
sound like U may B able to go in reverse @ a rapid pace
Best o Luck o

cya

Good work Dave..
Your typing skills are obviously FAR SUPERIOR to mine..
I'd be on My 5-6th beer by the time I tapped out that many words....LOL..

Lawsy have you seen this it needs to be in the next Monitor

Thanks, Men!

Ted,
I'll try and keep this one short. or at least shorter!
Unless Iv'e used the wrong formula, I make it 8 (eight) usable progressive shifts in the following sequence, using UNALTERED ratios.
8.75:1 6.68:1 4.37:1 3.78:1 2.17:1 1.66:1 1.31:1 1.00:1
I'm running a diff ratio of 4.10:1, With that spread I guesstimate that a final drive (diff) ratio of at least 3.73:1 or perhaps even better, 3.50:1 would be ideal, without risk of 'overgearing'.

Most of the shifts are using the close ratio box as a simple two speed splitter, like those early 5 X 2 Fullers, only one shift calls for the use of 2nd gear in the close ratio box.
As can be seen from above, I'd call it a 'usable' spread. Certainly alleviating the huge gaps between 1st-2nd and 3rd-direct in the original transmissions.

I am quite willing to be corrected if anything becomes glaringly obvious that I have overlooked.
Cheers, Dave

Meant to add, reverse gear in the "auxilliary" is blanked off as in the original posting. four reverse gears are more than enough! The reverse idler is only left there to help splash feed the back section of the box.

Dave.

Here U go Davo

C ifn U can crunch u're numbers down with thiz 4mule R

https://lh3.googleusercontent.com/3fwPtHUfWd3UuTcUEXdUzCzrC20v4Y-AV0lH4MJbGjfw4eLursg=w800-h1100-no

Best O Luck O

Blank n off the extra reverse may take away all u're fun
LOL

Cya

Bloody hell Dave
You carnt get much sleep of a night !!!
....................Billy......................

Yeah! Yer right Billy! Maybe should have been "confessions of an insomniac!"

Ted, You were good enough to send or post this to me once before, I follow it (even how they achieve the 0.71 final o'drive by multiplying the overdrives in each box), what I do not know is how to convert the steps expressed as ratios, into percentages. e.g. 2nd O/D up to 3rd U/D (2.48:1 --2.05:1) . There is probably some simple formula for doing it, maybe dividing the ratios into a hundred??

Some gear charts actually express the steps as a straight percentage INSTEAD of as a ratio.

Dave.