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I just bought a 1946 Maple Leaf 3 Ton Truck. I'm pretty excited and I should have it running soon. now my only concern is I would like to increase the top speed. I hear that the limit is about 80 km/h but I would like to be capable of highway speeds just in case. I would like to keep my two speed rear end but if I could re gear just the high gear to a more reasonable ratio that would work too. The current transmission doesn't have synchro mesh and that's a feature I wouldn't mind having. My issue now is finding a newer 5 speed transmission with a roughly 25% overdrive that I can adapt to my gmc 248 engine. I would like to maintain my 3 ton rating if possible. I found a ford ZF-5 locally for a good price but I'm not sure if it can be adapted to my engine and I would rather put a gm transmission on it if I can. Any thoughts?

A New Venture NV4500 from a 2wd gas Dodge pickup may be a good choice. They are durable and have a sufficiently long input shaft to allow the use of a 1" thick adapter plate. OD ratio is 0.73:1. 1st gear is a granny gear.
I think the ford unit mentioned has an integral bell housing, so it would be a bad choice.

Thanks for the advise! I looked up the NV4500 and it seems like exactly what I'm looking for. Im going to head down to my local scrap yard next week and see if they have a truck I can pull one out of.

double post

Getting up to highway speed is great. Just make sure the brakes are up to hauling it back down. Remember...these old rigs had their own design limits.

Another option is to get a 2wd gm nv4500 (these are cheap), swap in the dodge gas input shaft, and machine the adapter plate. That's what I did on my little 1/2 ton conversion.
http://67-72chevytrucks.com/vboard/showthread.php?p=6488778&posted=1#post6488778

How did you get the speedometer hooked up? The other advantage of the Dodge transmission is the mechanical speedometer gears on earlier models.

WELCOME,wateverpratt!! Just read your post on the O.D. swap! NICE!! I have an SM 420,in mt T.F. '55 6500,and I'd like a nice,inexpensive swap. I "lost" a bid on "fleabay",for a Clark "O.D." unit,and may be for a reason. Your NV 4500,is about 1/2 the price of that trans. I was bidding on,and that was without the cross member,linkage,or shifter. You got yours installed,for the price that I would have been paying for parts,and that doesn't cover hidden expenses,such as:trans. fluid,etc.! WELL-DONE!! THANKS!!

Another option is to get a 4500, machine new mounting holes based on the bellhousing pattern in the front of the 4500. Need to register on the 5.125" retainer dia.

I didn't see your post whateverpratt, but thats exactly what im doing! I got a gm NV4500 with 175,000Km on it for $140 with the shifter, I ordered the dodge input shaft and I'm going to machine an adaptor next week. Great minds think alike I guess. I am curious about the spedometer though. That could be my greatest problem.

Did you happen to keep the dims and specs for that adapter ?? I would be interested in getting one from you.

I'm looking at getting a little more out of the top end on my rig as well. I found a unit called a "Brownie" auxiliary tranny that I'm unfamiliar with. It supposedly has a gear under and two over? It has the tranny,linkage,and two cross members looks like an easy addition to the rig.Also has a better drive line brake than the truck has now. I can get it for $300. It seems pretty period correct for the truck. Any opinions on this style of overdrive?

The NV4500 does sound like a nice choice,but I have not seen them that cheap around here.

What model auxiliary transmission Is it? Unless it is huge (as many were) then go for it, and price sounds great!
Brown Lipe was a brand name before Spicer bought/merged with them, that's where the nick name "Brownie Box" came to be and stuck for "auxiliary transmission". Watson is another old brand, Spicer also assumed their line.

Very very unlikely it has two overdrives and one under, I know of none. Most likely to have an under, direct, and over. Some don't have overdrive though, so be sure you get what you need.

The Spicer model numbers could be 5831 or 6xxx and after that the 7 and 8 thousand and even 12,000 model numbers are quite large, more than I'd want in one of these old 2 ton trucks.

I have a 6041 four speed for one of my trucks, going in a 1 ton and almost too large for that.

Thanks for the info Grigg. I will go back and look for some numbers and more info on it this Sat.

Brownie

Was watching this on EBay a while back just to see what they went for. Got pretty spendy.

I agree, plenty speedy. The first numbers are the ENGINE torque capacity, the third number is the number is speeds, I. E., 3 or 4. There are no parts but bearings, so pull the cover to check. Having an integral brake: drum or Truestop is a plus, especially if you don't have cable brakes. A 6000 series is sort of overkill for a pickup, but duable. 5500 and 5800 series are great for pickups. Make sure to get the shifter mechanism, and driveshafts. $300. Is a good price as Grigg said. Check the innards first, treat them with care, use OD only with light loads, shift to direct with a load, not loading the cluster then.

God luck.

That looks,"just"a little smaller than the one I'm looking at.

Really cool truck, Straightjacket. Love the deco cabovers and yours has a great look. What are your plans for the body?

here's a picture of the 6041 I picked up.
https://picasaweb.google.com/lh/photo/qQJxqTGWw7epptXBsObIWNMTjNZETYmyPJy0liipFm0?feat=directlink

It is somewhat larger than the old Chevy 4 speeds for comparrison. I'd guess the weight around 200lb, could be more with brake and all, ought to be less than 300 though.

How do you create a workable linkage/shifter with one of these beasts in an old truck?

In the same photo album are pictures of the shifter tower, GM made I think. Looks like top of an SM420 and shifter stick may be interchangeable.
Spicer also made a more compact shifter, could be bolted to side of main transmission or to the frame/bracket on frame.
Linkage is just 2 rods and appropriate clevis ends.

Grigg, that looks just like the one that I've been checking out. Although it still has the mounts on the side.

JW51, don't want to highjack the thread on my truck. I've got a post"41 COE Betty" that I'm trying to update along with my photobucket in the sig. Keeping her fairly stock for now.

What kind of torque is that rated for ?

I need something to get my '52 6400 up to highway speed. I have a 292 built to around 350 lbs ft for it.

A 6000 series Spicer auxiliary is rated nominally for an engine max torque (at flywheel) of 600 lbft.

350 lbft is not much at all.

The torque is a "paper" estimate based on components installed. 350 should be minimum, so a 5000 series would be good for me too. Is yours a 4 speed then ? What is the extra gear ? Another reduction ?
Got any spares ?? I don't need a shifter as I would plan to leave it in OD.

Right, sounds like you could use a 5831. when searching for them you may find a letter after the model number, that will designate a different ratio for both low and over, or low and lower as some are. They always have direct.

Some info and links about them here
http://www.4btswaps.com/forum/showthread.php?14140-5831-b-ratios-%28Auxilliary-Transmission-Info%29

The 6041 is a 4 speed, two lows, direct, and an over. Ratios are 2.14, 1.24, 1.00, and 0.86:1 for 1st through 4th gear respectively
I don't know of any models with two overdrives in the auxiliary.
little more info on mine
http://www.4btswaps.com/forum/showthread.php?14924-3-53T-Silver-For-a-1952-Chevy-1-ton-pickup/page4

Shifter could look like this and be mounted centered directly behind the main transmission shifter.
https://picasaweb.google.com/lh/photo/vbs2LCCJzp4rbpykXRModNMTjNZETYmyPJy0liipFm0?feat=directlink
You do NOT want to leave it in OD all the time. The original literature and recommendation was to only use OD in the auxiliary while in the higher gears of the main transmission; so as to limit the total amount of torque you could put through the OD gear. Ideally you'd leave it in direct then shift into and only use OD as needed on the highway. You can also use any of the auxiliary gears to split gears or otherwise make for more progressive shifting with the main transmission, still avoiding OD while in low gears of the main. Figure out the ratios and which shifters to move where when.

I don't have any extras. These things are perhaps not expensive at all if/when you find them, but finding them is the key part... Therefore holding on to what you want/need is worth more than the search to find it again, if you even get that lucky.

Thanks for all the info. I'll have to start searching around here, but many of the junkyards were eliminated and housing developments built on the land.

Bummer if I can't leave it in OD. I don't think I will be needing to split the gears, but you never know. I do plan to pull my car trailer with it. That is why I had the 292 built.

It would be like the "old" days of driving a dump truck with 5 and 4 speed transmissions. "2 sticks" we called them. I graduated from that to a Fuller 13 speed in 1985 and just retired from 28 years as an O/O. Sold my '92 Pete last year. The 2 ton is my "big rig" now...

I have a Spicer 5831C in my '46 two ton. It splits the crash box under and over in each gear of the main box, and can be shifted progressively through all 12 combinations if desired. Although the first 6 combinations in my case will get you up to about 15 mph with the engine wound up.

Grigg is correct in that the OD is best used in the higher gears of the main transmission to limit the strain on the OD gear set. Its not that the overdrive is made of glass though. As long as the operator is using a portion of his head and has a foot made of something other than lead, there are situations where overdrive can be used with the lower main gears.

I must admit, 1st over is a nice combination for idling through some parades....

I find that the Spicer isn't that difficult to shift, and it quickly becomes second nature to slip it into OD as the last shift getting up on the highway, and its the first gear to come out of on a downshift. Even loaded I find that splitting anything below 3rd in the main transmission doesn't gain much for the effort.

Well, I went a different direction today. An NV 4500 out of a 1993 1 ton Chev came up on craigslist and I bought it. I got all the hydraulic clutch parts and the crossmember.

Now I need to find a 20 tooth input shaft, bearings, clutch fork, pivot ball and throw out bearing. The shaft is severely worn for the pilot bearing and the fork was never greased...