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Topic Review (Newest First)
03-07-2020 09:08 PM
Hi All, Just a few thoughts on how to beef up an already legendary light truck transmission.
I’ll cite the New Process NP435, but would say that the SM465 could be done almost as easily. I, personally like the NP435, easy to get parts for, easy to set up, made them for almost thirty years and utilized by too many manufacturers to mention, yes, even Chevy used them for a few years.
I have had, and still do, versions by Ford, Dodge and International here that I have mixed and matched quite successfully over the years. Disregard the input shafts and housings (all different lengths and clutch spline counts) as well as output mainshafts and their differing setups. We are concerned with the straight internals only. All the ones I have had, had the common 6.68:1 first gear,(except for one NP445) with only one difference that I have found, some run a spacer BEHIND the mainshaft first gear, others have a machined step on the actual shaft.
Why bother trying to beef up such a well designed unit at all? These things were virtually unchanged internally since day one. Well, I had a special application which called for it, and reading on different forums, blokes have been shoveling insane amounts of HP into them, with rarely a failure.
My project called for an NP435 to be run BEHIND an already existing transmission, an NP445 close ratio version, coupled by a short jack shaft to an “Island” or “Divorced” set up. Motive power was a compact 2.5 litre Turbodiesel, hardly enough to worry you would think, but multiplying the torque out of the engine and into another box, reasoned that I’d be pushing the boundaries.
So, after reading quite a few articles on different forums, thought why couldn’t I improve things a bit in my application?
Starting off with the bare case, and depending on what vehicle you are driving, this would work equally well with all. Bit of machining involved, but kept to a minimum. Once stripped bare and cleaned up internally and externally, send the case to your neighbourhood machinist. Get him to machine out the COUNTERSHAFT bores to take a roller bearing that is not only easy to get, but will fit the input/output tips. You could also use tapered roller bearings or cups, same as most of the larger truck transmissions use, similar to what Spicer uses on their auxiliary units, You may even get away with simply installing a similar bearing in the housing at the rear of the case. The front bearing would call for a bearing sealed on one side, when fitting the transmission to the bellhousing, a simple hand made gasket or good quality sealing compound is not going to alarm you as to adding thickness, a few thou involved won’t worry the clutch set up or the pilot tip. With the case bored, reinstall the countershaft as per original, don’t forget the thrust washer or shims to give you the correct end play. Once you have that rear C/S housing adjusted and tightened to specs, job done. Whatever input shaft you are using, I’ll say Ford or Dodge,(but also works with Chev or Inter), both major uses of this box, the input shaft tapered bearing can be upgraded to a superior quality, but doubt it would be necessary, like wise the needle rollers inside the input gear which sits on the mainshaft tip. Reassemble the mainshaft components as per your relevant workshop manual. The only other mod is to upgrade the rear output shaft/housing bearing, it is a common size to all users and very easy to get hold of. I went for an angular contact bearing simply because I was modifying it for a different purpose. Is it worth it? Debatable, unless you want to do really serious work with it. I was modifying for a different purpose, increasing the already considerable torque I am going to put into it, machining kept to the minimum, keeping costs down.
Over here in Australia, we simply don’t have the access to the sheer volume of after market components that you guys enjoy, so we modify and adapt a lot. Over the years, have done some weird things myself, Toyota Dyna 5 speed overdrive to AMC Rambler 343 V8 into a CJ6 Jeep, for one, try and get an off the shelf bellhousing for that! Had one adapted, to my knowledge the bloke who bought it is still running around with it after twenty odd years. Read quite a few of the popular forums you guys have going for you over there and one thing strikes me, a lot of readers/contributors seem to think that unless they can buy an over-the-counter adapter or bellhousing, it all becomes “too hard”. A bit of thought, ask the questions and sooner or later a solution will appear. I have a really switched on machinist on tap, made me an adapter to bolt a Ford bellhousing to the Perkins 2.5 TDI, using all common Dodge case and clutch parts, only thing extra I had made was a special clutch plate to suit the Dodge 23 spline input shaft, even machined down the input cone to bolt to the Ford bell, using common Ford clutch throwout lever etc. So it can be done with a little ingenuity. Ford, to Dodge to Chevy can all be adapted quite easily, mobs like Advance and Novak will supply all parts if you want to go that way. I recently bought a C30 Chevy tray that has the std 350 and SM465 box, in good nick but don’t like the ratios for what I want. Am looking at using the NP445 all synchro close ratio box behind that engine. To best of my knowledge, no Dodge to GM bellhousing available, so will look at getting a Chevy input shaft and nose cone and bolt into the Dodge box, replacement parts still available, but would have to import them. Then bolt the existing GM bell to the Dodge, they both have the common 5.125” input housing diameter, a matter of redrilling either the box or the bell to match them up. I’d set it up so I could install locating dowell pins between the box and the bell. Anyhow, that’s the plan.
I had the NP445 imported from the States years ago, to put into a 2WD US Postal Jeep, behind a Ford 300 big six engine, but sold the postal on and it is too good a box to unload, I’ll hang onto it, like to fit it behind the V8 in the C30. Not going to be carrying huge weights, make it a bit more driver friendly.
I had modified the “island” box out of a standard Ford/Dodge NP435 simply by changing the input tooth count on the shaft and fitting it into a Dana 20 cast iron T/C housing. Currently running one of those “Weddle” transmission pumps, probably not absolutely necessary as the internals of the box are otherwise back to standard assembly, would splash feed OK. Runs like a clock in the project chassis, but can see where I could have improved it even more by making it into a “compound” box, bolting two NP435’s end to end. Have spoken to my machinist and he reckons he can turn up an adapter housing out of steel (not worried about weight, want strength) pretty easily, just him getting time to do it. If I go ahead with it would use a std NP435 (6.68:1 first) as the main box, and the already modified NP435 as the compound section. Gives a better spread of ratios than the close ratio NP445. Lo-Lo would give me a compound gear of around 18:1, which you would never use, even Ist gear U/D still gives about 9:1 running 5.27 diffs on 7.60X16 tyres on the project vehicle, serious gearing. Again, why would you bother? Always have been a tinkerer and retired so can play about a bit, besides, gone too far already and reckon it’s a viable proposition, although has cost me a good quid! See a problem and thought, can I do anything with all these boxes in the shed? I stress I am NOT either a mechanic or an engineer, just spent all my working life driving trucks and operating plant. I fully expect a certain number of others will no doubt take me task for trying to reinvent the wheel, but I have seen some great projects assembled when others have cried, “won’t work”, Throwing money away, go and buy something off the shelf. Anyone can buy adapters and parts from their local auto supermarkets, but if you are of a mechanical bent, you will probably say, let him go, it’s his time and cash. Like I said earlier, we modify, adapt, alter quite a bit over here simply because for so many years we didn’t have access to all the great gear you guys enjoy, so we have had to make do. I have seen many wonderful things assembled out in the bush, when blokes haven’t been able to buy what they want, so they modify.
03-03-2020 03:05 PM
'Mad Max' AFAIK the ~5.125 were also available in front of the early and late (overdrive) A-833 4-speeds - not sure about the others. (I actually need an 833od bellhousing and fork...)

Hydroboost is always a good idea in my book... - I've used both Mopar and GM versions - both do the same thing the same way
03-03-2020 01:24 PM
Originally Posted by Dave 64 View Post
I take it that the 5.125" centered bell housing is the TRUCK version, the smaller 4.8" is the CAR bellhousing?
Any fifference in I.D of the clutch housing?
Truck running the larger diameter plate?
What about the hydraulic throwout lever set up, my workshop manual does show a hydraulic set up, but later model than 1975.
Also, whilst I'm about it, mine has the "Hydraboost" brake assist and am thinking of using a firewall mounted booster, again later model??
Dave 64
Truck/car doesn't matter. 5.125 is early, like 1960s and earlier. The 5.125 bells are a chore to find with the butterfly pattern (most had the early pattern) and never came with hydraulic clutch. 4.8whatever is later, like 1970 on. Depending on application and age the 4.8whatever bells will have hydraulic clutch bracket. They can both house the 164 tooth flywheel that can take an 11" OEM clutch. (talking about Ford specifically here)

I have no idea what you mean by hydroboost. Brakes are totally separate.
03-03-2020 12:58 PM
Dave 64 I take it that the 5.125" centered bell housing is the TRUCK version, the smaller 4.8" is the CAR bellhousing?
Any fifference in I.D of the clutch housing?
Truck running the larger diameter plate?
What about the hydraulic throwout lever set up, my workshop manual does show a hydraulic set up, but later model than 1975.
Also, whilst I'm about it, mine has the "Hydraboost" brake assist and am thinking of using a firewall mounted booster, again later model??
Dave 64
03-03-2020 06:37 AM
'Mad Max' ...one of the best engines I ever had was a rebuilt (stock) 318 with 360 heads - set it up with a 4bbl intake and cam and that thing ran awesome. I'm likely to build a warm 360 with aluminum heads for our 71 Demon which should run all that much better.
03-02-2020 03:28 AM
arse_sidewards You know you can get a Chevy bell-housing that has the same 4.8-whatever center as the Ford, right?
02-29-2020 08:42 PM
Dave 64 Been having another think about this, reckon I can unload the NP4350 (NP445) Dodge box, reasonably easily, and thinking if I can find the close ratio (4.02:1 Ist gear) all-synchro version of the Ford T19, may save a fair bit of stuffing about.
If I have this right, going by what I've read both here and on some other forums, If I can get a box with the "ears" undrilled, it is a matter of getting an adapter ring to suit the Ford bellhousing to the Chevy 5.025" centre.
What about input length stickout? Clutch spline shouldn't be a problem, long as I get the CHEVVY plate, not the FORD.
What about input bearing/bush adapter?
Other thing is, want to go full hydraulic clutch throwout, have the full setup to suit the Ford NP435, so a bit of ginning around, should be able to adapt OK?
Bit of swapping around for rear xmember mount, speedo cable etc.
Would be going from a Granny gear SMH465 4speed to a T19, top gear the same, but better spread in the lower gears.
Intend going behind a SBC 350 V8'
Thoughts?? Dave 64
02-15-2020 01:21 PM
Dave 64 Thanks for your input, Guys.
Probably not worth the ginning around as you say. Had the 445 box sitting here doing nothing, but just may unload it to some Dodge bloke, they are often looking for a replacement over here for the 435's.
02-13-2020 10:44 AM
crashnzuk To add to what he ^ said, if you just want a close ratio box with less hassle, use a modern 5 speed such as a 3550 or 3500 (which ever one chevy used) and it will bolt right up. If you break it, there's a replacement waiting to be plucked from the yard of some guy with a mullet. If you don't need the o/d due to your current gearing, simply don't use 5th gear. If you do find you need it, BONUS! No sense in running the Dodge spec box just because you have it.
02-13-2020 10:24 AM
Elwenil If you break it, it's done. There are no hard parts available for the NP445. It's really not worth all the trouble to swap in a 4 speed. You would be better off spending that time and money on a modern 5 or 6 speed with overdrive.
02-13-2020 09:00 AM
crashnzuk I think you'd be better off finding a Ford close ratio t-19 than using the np445. The 445 isn't very common, even in the states, and Ford made t-19s by the truckload. I'm pretty sure all of the adapter companies make stuff to mate these to chevy engines because it's easier to do than use anything from Dodge. Dodge stuff is kind of it's own brand of different.
02-12-2020 05:55 PM
Dave 64 Been following these posts with some interest.
I have a '75 Chev with the 350SB over here in OZ, have an NP4350 (some call it the NP445) close ratio all synchro box out of a Dodge which I kicked around the idea of replacing the Std SM465 granny gear with. It is only a weekend warrior to tool around with, so higher starting first gear won't worry me.
Both have the clutch throwout arm in the same position, just eyeballing it I would think the easiest solution would be to simply add a machined alloy (or steel) spacer block between the original Chevvy bellhousing and the front face of the tranny. NO? I do have the original Dodge B/H but too much ginning around. Easy enough to have a pilot tip extender machined up out of brass stock to suit the Chev flywheel, and have had in the past had clutch discs made up with differing centres (Chev 10 spline--Dodge23 spline, had one made up recently to go from 23 spline Dodge to Perkins 203, but thats another story).
Some alteration to the tailshaft probably needed, but thats straightforward.
Been kicking this around for a while, no gain in final road gearing, both 4th direct 1:1, but the tranny in remarkably good condition, had it sent over from your way for another project. All I had to do was chuck in input/output bearings and seals, fresh oil, came up like a newbie! Would be interested in what you guys think, Dave
03-19-2009 04:36 PM
W_A_Watson_II My 323 (318 bored 30 over) has been great, just beed a better tBI/Carb. The crappy Holley 502S is hit or miss.

03-19-2009 12:19 PM
Elwenil A 318 revs very well with a little head work. The 318's bad reputation comes from the fact that 90% of them out there are either mid '70s-'80s emissions engines with Lean Burn and other crap that kept their stock power at the 150 HP level and TBI setups that don't offer much flexibility over stock. Ask anyone who owns a late '60s to early '70s 318 and they will tell a different story. 230 HP stock with a 2BBL and wakes up real nice with a 4 BBL. 318's are dead simple to tune, reliable as any inline 6 cyl and it's small stroke and internal balance will rev well beyond it's limits with the right airflow. A buddy of mine used to street race a '73 Dart with a nicely built 318 on pump gas and the only 350s that ever beat him were full tilt race engines. Big blocks would have trouble against that little engine to the point that the scuttlebutt was that it was actually a 340. It was nothing more than a 318 built with some thinking and good parts.
03-19-2009 06:31 AM
bronkho31 I dont like to argue, but why not.....Honestly I dont like these 318 really at all....seems like dodge went out of there way to make these engines exspensive, ugly and hard to tune...maybe its just me, but I dont think they handle rpms as well as a 350 or a 302 and I have a roller 318. I'm sure I could think of more reasons but I wont because I have seen my fair share of 350s gernaded also....

Making motor mounts dosent bother me, ive been wanting to lower the engine anyways...but...finding a tranny/tcase to bolt up to the 350 may be what stops me. we will see....

Thanks for the help
03-18-2009 06:57 PM
LegendKiller89 I wouldn't do the Chevy 350 because then you have to fab up some mounts and you will have to address a bunch of other issues the biggest being the Tranny. IMO the 318 is more reliable then the 350. And I'd take a 318 any-fucking-day of the week. Sell the 350 and get some decent money for it and then strip and scrap the wrecked Chevy. Then get yourself another 318 and your good to go.

Or get yourself a 360 even better!
03-17-2009 10:44 AM
crashnzuk Swap in a 360 and use the TBI off of the chevy, it should work fine if it is set up similar to the 350 exhaust and intake-wise (no headers or huge exhaust). Chevys have a shorter input shaft on the trans. Either use all Chevy or stick with Dodge.
03-16-2009 10:18 PM
Originally Posted by arizona-v10 View Post
searching craigslist thousands of miles away
damn I'm bored
Welcome to the Internet. Full of boredom, bullshit and porn, lol.
03-16-2009 10:06 PM
arizona-v10 Just a quick thought, on Peoria's craigslist there is a magnum 318 out of a Dakota for sale for 500$, plus parts because it's still in the truck. Make that guy an offer that you can afford and take every thing he will give you. Like fuel pump, computer, or maybe the whole damn truck. Then sell your chevy engine for more than you buy the Dodge engine for and be happy, with your new cool ass multi point fuel injection motor, post pics on pirate so we can see your new mopar power plant, in it's new loving home between the framerails of truck that is going to be wheeled.
searching craigslist thousands of miles away
damn I'm bored
03-16-2009 08:52 PM
bronkho31 Im not worried about resale....if you have seen pics of the rig u would know why.....but you all definetly have me thinking....
03-16-2009 07:49 PM
W_A_Watson_II ffdustyw,

Thanks. The site was where I started, I share my stuff with a lot of Dodge Power Wagon guys over at Dodge Power Wagon Forum and at G741. My own WEB site was the simple soution when I started, Only been watching the Pirate site for about 6 months now.
03-16-2009 07:35 PM
Originally Posted by W_A_Watson_II View Post

No thread, but a full WEB site full of pictures and cometary. You can check out my M37 at: My 1953 Dodge M37 WEB site

Oh by the way I love your Truck (and thread)!
Thanks, I am checking it out right now.

EDIT: D*mn! that is one hell of a website. Good pictures. You need to start a thread here.
03-16-2009 07:20 PM
jeeyota00 pm crazycjman. he is running a tbi 350 with a 435 behind it, works great
03-16-2009 07:13 PM
W_A_Watson_II ffdustyw,

No thread, but a full WEB site full of pictures and cometary. You can check out my M37 at: My 1953 Dodge M37 WEB site

Oh by the way I love your Truck (and thread)!
03-16-2009 07:12 PM
Originally Posted by W_A_Watson_II View Post
The Dodge NP435 has a 23 spline (or in some older units 10 spline) input shaft with an 8-3/8" stickout
The GM / Chevrolet NP435 has a 10 spline input shaft with a 6-1/2"

Notice the input shaft length differences.

I'm running a 68 318 and 65 NP435 (10 spline) in my M
Do you have a build up thread?
I would like to check it out. There are a couple M38's down the road that I could pickup cheap. I am afraid I would end up taking everything out of my rig and building a new rig.
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