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Crap !!! Does anyone have a copy of all the pics and ratio tables?? I see they are gone Should have downloaded them when I had the chance.
Originally Posted by 38 coupe
I have been interested in smaller auxiliary transmissions for a while. When I got interested I hoped to find a nice web page or forum thread that gave a lot of information on the smaller auxiliary transmissions. This thread has been very helpful with gathering information, but the information is still scattered. This post is my attempt to put together the most useful information I have in a consolidated format. If anyone notices a mistake or omission please contact me so I can correct it.
The history of smaller auxiliary transmissions is a bit confusing. Once you are dealing with trucks newer than the Model T era, three names are prominent: Brown-Lipe, Spicer, and Watson. The cause of the confusion is that at some point all three companies were combined. I have a 5831 and the data tag has all three company names on it. As near as I can figure out most of the Watson transmissions were designed for 1½ ton through 2 ton trucks and most of the Spicer transmissions were designed for 2½ ton trucks and larger. The exceptions are the Watson 2021 and the Spicer 4800, both which were designed for ½ ton pickup trucks. Also designed for ½ ton pickup trucks was the Warn Auxiliary. If you are planning on installing an auxiliary transmission in your truck you should do some careful measuring to make sure you can make everything fit. I also need to make a huge disclaimer at this point; I have not installed one of these yet. My current plans are to put a Spicer 5831 into a ¾ ton pickup. I am still in the planning stages.
I'll start with a table of gear ratios. I included the transmissions in this list for two reasons: first these are small enough to use in a 1 ton or smaller truck, and second I could find some information on them.
The Watson transmissions most frequently mentioned in online discussions are models: 31M, 39M, 41, 42, 43, 44, 45, 46, 47, and 48. I have seen pictures of these Watson transmissions used in ¾ and 1 ton trucks. Watson used a basic design and changed the model number to designate different gear ratios. The 31M and 39M were side loaded transmissions and did not have cast in mounting locations. The 41 through 48 transmissions are top loaded with four cast in mounting holes.
The 31M and 39M transmissions look like this
The Watson 41 through 48 transmissions look like this
The Spicer transmissions most mentioned are the 5531 and 5831 models. The 5831 series transmissions were the updated replacement to the 5531 series. Both series were available in several ratios. These are top loaded transmissions with the shifter rods and forks carried in the top cover. The 5531 has cast in mounting holes at the rear of the transmission. The 5831 does not have cast in mounting holes. I have seen pictures of these Spicer transmissions used in ¾ and 1 ton trucks.
The Spicer 5531 transmissions look like this
Here is a Spicer 5531 parts manual
The Spicer 5831 transmissions look like this
Here is a Spicer 5831 parts manual
Here is an excerpt from a GMC shop manual that covers the Spicer 5831
Warn, the company of Jeep winch manufacturing fame, made an auxiliary transmission at some point in the 1960s. Unlike all the other transmissions I am writing about the Warn Auxiliary has a planetary gear set. I include it here mostly because I lucked into a NOS unit a while back. These were designed to fit between the main transmission and a married transfer case. I'm not sure how well one of these would hold up to 1 ton truck use. I think it looks like a great unit for a vintage ½ ton pickup with a stock gasoline engine.
Here is an add for the Warn Auxiliary
I also have scans of the owners manual / parts list / instruction guide
Here is a picture of a Warn installed between a main box and a transfer case
i have a 97 f super duty i use for my welding truck, i need more speed and less revs my grandad use to restore model t fords and he rebuilt ruckstell axles andmessed around with moore overdrives and underdrives. i was looking at 2 speed rear ends not practical so here i find this thread i need a Brownie i drive interstate and that rear end is just too dam low geared for todays speeds i got the five speed standard what kind of nightmare am i looking at to change this im a welder so i have the ability to cut grind and weld? any info from yall would be awesome. oh i need to buy a brownie so lmk
i have a 97 f super duty i use for my welding truck, i need more speed and less revs my grandad use to restore model t fords and he rebuilt ruckstell axles andmessed around with moore overdrives and underdrives. i was looking at 2 speed rear ends not practical so here i find this thread i need a Brownie i drive interstate and that rear end is just too dam low geared for todays speeds i got the five speed standard what kind of nightmare am i looking at to change this im a welder so i have the ability to cut grind and weld? any info from yall would be awesome. oh i need to buy a brownie so lmk
Hello,first what is the wheelbase you are working with?Do you understand how spicer auxiliary trans are rated? I have a 6041 in a 79 F350 CC (60=600 ftlbs of input shaft torque,4=4speed ,1=cast iron,as an example.There are also different ratios for each model.If you go back a few pages you will find my install and kinda see how it should go. If you have any questions just ask.
Chris
Hey guys; I hate to resurrect an old thread but I have a couple of these spicer overdrive transmissions, namely; 5831d, 7231d and 7041. I am trying to figure out what works best for my truck. I have a crew cab f350 dually conversion with zf5 4x4, long bed. I currently like the 4.10 gearing given that I occasionally pull heavy with it. However, 90% of the time, I am running empty. I will like to drop the rpm for a bit more efficiency when highway cruising. I honestly think it isn't worth the headache, time and money fabbing and installing an auxiliary trans just to gain a mere 14% overdrive. Looking at the idi torque and hp curve, 25 to 30% overdrive seems like a sweet spot. That's why I am thinking Regearing to 3.55 along with installing an aux with underdrive and overdrive might just be the way to go. I am leaning towards using the 7041 since it affords me the flexibility of a "usable" under drive along with a 17% overdrive even though the double underdrive is virtually useless for my application. The flat top might also comes in handy when considering proper driveline angle and vertical clearance. The downside is the size. It is significantly bigger than a 5831, with an air tank, dual fuel tank, and transfer case, space is premium. The only way to do this will be Converting the 5831D to a 5831E giving me a usable under drive of 1.23:1 and 27% over and still keep my 4.10 but that will require changing the entire main gear and counter gears on the thing. At over $200 a gear (if you can find one), it is simply not worth it. Finding reasonably priced 5831A or 5831E seems less likely than spotting a unicorn. That's my reasoning behind wanting to use the 7041. Any suggestion is greatly appreciated.
Bump if anyone is still here….what’s the GVWR on these units?
I know the 5831,6041,7041 etc all have the first # represent max torque but I was curious what the GVWR is on them. I saw an old brochure of a 1957 white 9064 with a 7231 option as an aux trans and the GVWR in another page ranged from 43k to 72k. The engine made like a monsterous 328 lb ft of TQ. I guess my point is, if the 5831 can handle 500 TQ but is rated at 35k GVWR it can probably handle 900 TQ at 25k GVWR, right?
Not as far as I can tell... the short input shaft on my 5831B is not suited for a throwout bearing or clutch disc, just a flange. There is a large "nose" which fits in a pillow block for the front mount. I don't think there's a bellhousing mounting pattern on the front either. Besides, that would move your main trans a long way back.
Some 20 years ago I put a 5831B behind my FE with NP435 ('65 F-350) and it worked well, although fabricating mounts was a little challenging.
Currently I'm in the process of converting the 4-speed to a Clark 285V 5-speed. The trans is about 3" longer than the NP435, so I have to move the brownie back at least that far. The intermediate driveshaft was actually a splined yoke pair with no tubing at all. Not reusable because the rear brownie mount would be right where a frame crossmember is. I may be able to hang it from that crossmember, redesigning the mounts entirely... will be looking at it soon.
Edited to add: I remade the front mounts using a piece of angle iron, and there happened to be frame holes exactly where I needed them. The rear mounts I fabbed long ago are reusable as-is, but I'm going to have to drop the 30 gal. sidesaddle tank in order to drill the bolt holes on the driver side. Front crossmember using the old rubber isolating mounts.
Rear mounts made from heavy plate and c-channel. The frame brackets have rubber isolators too.
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Should have downloaded them when I had the chance.
