Yeah, another reason I really would just rather marrying everything is so that I just don't even have to worry about strength or longevity of the u-joints.
If I did go with u-joints, I completely agree with you and have read elsewhere, that they need to have "some" angle in the shaft so that the needle bearings actually get to moving around. I was going to do what you mention, simply offsetting the brownie a bit either up or to the side. Somewhere I have written down the recommended minimum angle for different size u-joints.
My 5531 has 4-bolt flanges on both ends. If I could make 4-bolt flanges for the transmission and x-fer case (where there is a machine shop there is a way...), then why couldn't I just bolt the cases together? My only concern is how to ensure the input/output shafts are concentric with each other, as well as what kinda tolerance I need to hold for concentricity? My thinking was that ANY offset in the two 4-bolt plates from being concentric would lead to some pretty good vibration and ultimate demise, but if I'm a couple thou' off from concentric would I notice it?
The problem with R&P options for the axles in the M-715's is that unlike "modern" Dana 70's which have a 1/2" pinion offset, the 715's D70 has a 5/8" offset. I have asked several people but never got a true answer on whether a 1/8" ring gear spacer is a viable solution, but a few people have said that I should not go that route. I'm running 38" tires, which is taller than stock tire size, so I have a bit of "rubber OD" there. If I stick with my gas engine, then I'll be good for RPMS. If/when I do go the diesel route, I would definately go with the 4.56 gearset. That with the double OD from the transmission and Brownie would have me at about 1450 RPMS at 60, and 1600 doing 66.
It looks like your thinking is on the right track. I have not used them, but there are spacers available to allow "thin" 4.56 & up ring gears to be used in place of a "thick" ring gear -- that is with a differential carrier that has a higher offset. (There are also aftermarket "thick" 4.56 & up ring gears.) The problem with the spacer is that the bolts are in shear at two points and there is more bending load placed on them. This can be minimized with custom shoulder bolts and a hardened spacer with holes that are a tight fit on the bolt OD. I do not know, but suspect that most spacers have oversize holes to make assembly easier. If it is only 1/8 inch, many people would be tempted to use the stock bolts. Your double OD solution with 4.56 gears is probably a better way to go.
I have twice adapted OD's to 4-speeds using a closed adaptor machined to maintain concentricity and both are still in operational order after a lot of miles. I was intrigued by the open, yet rigid adaptor in one of your links. If done properly, it could be tested for concentricity with a test indicator while assembled, but without the bolts in the couplings. I cannot give you an exact number, but even one thousandth of an inch would probably be too much error in concentricity. The shorter the distance, the more critical the tolerance on concentricity. One test would be to see if there was any noticeable binding after assembly. When the output shaft is rotated, any runout would be able to be felt in the input shaft of the assembly. Anything but total smoothness would indicate a problem.
Last edited by acheda; 05-01-2008 at 07:42 AM.
Reason: correct error in wording . . .
In the hope that my thoughts may be useful to someone:
Please refer to the pictures in the first link in sarm715's first post (#20 in this thread) to better understand what I am musing over.
I have made two closed adaptors for mounting overdrives on 4-speed transmissions. The first one was made from actual pieces of transmissions that were milled so that the joined surfaces were parallel to the original machined surface. The cast iron was welded with high-nickel rod and the bead length around the outside provided adequate strength. I aligned the pieces coaxially by dialing in the bores in a vertical milling machine and then clamping them together before taking them to be welded.
The second adaptor was a 6" diameter thick-wall piece of steel pipe that I welded thick flange steel plates to. I then turned the entire assembly between centers. This included turning the entire outside diameter of the pipe surface, turning the outside diameters of the flanges, and also facing the opposite ends of the adaptor flanges. I then had plenty of reference surfaces so that I could mount it in a large 4-jaw chuck and machine the bores and counterbores as required, including flipping it end-for-end to to the other end. This adaptor was over a foot long and this system worked very well.
I am quite interested in the open adaptor that has two plates spaced by six columns. With my second overdrive I actually wanted a "wet" adaptor -- I used it to provide an extended oil supply for the overdrive unit, including a gear to sling oil from the sump of oil in the adaptor to a gutter that carried it directly to the sun gear in the same manner of the original Warner design. Any auxiliary transmission that is designed to be mounted separately will have the necessary front shaft support (two bearings) and seal, plus a deep sump with a large oil capacity, making an open adaptor no problem.
I think that the pictures show the idea well enough -- I want to discuss how to ensure that the shafts will be properly concentric and coaxial. First some definitions: concentricity is a property of circles and a point like the center of a circle is a circle that has been shrunk until the radius is zero. Being coaxial is a property of cylinders and a cylinder shrunk to a zero radius is a line -- it is also fair to state that two lines (the axes of cylindrical shafts) are coaxial. When we use a test indicator to measure the run-out of a bore or a shaft, we are only making a simple measurement of concentricity. In order to assure a coaxial relationship, we must measure two circles that are spaced as far apart as possible on a shaft (or bore) while using the other shaft to provide the sweep motion for the indicator. If two circles concentric with shaft "A" are concentric to the axis of shaft "B", the two shafts are coaxial. This requires rotating shaft "A" while shaft "B" is stationary and then rotating shaft "B" while shaft "A" is stationary on the first circle and repeating this for the other circle. It is not as complicated as it sounds, but one should remember that a single concentricity is not enough to assure that two shafts are coaxial.
In machining an adaptor, we can count on the factory shaft and mounting flanges to have a concentric relationship with the flange counterbores and to be perpendicular to the shaft axis. (We can check this if we do not trust the factory.) If this is true, all we need to do is make the adaptor with parallel surfaces and bores that are coaxial -- this is the sort of job that lathes are made for.
Machining the two plates required for the open adaptor is relatively easy -- keeping the relationship of the bores coaxial is more difficult. A permanently assembled open adaptor could be held together with fasteners or welded or both. The plates should be rough-machined oversize with the interior surfaces given their final finish. The columns are then machined to the proper length with care taken to have all of them exactly the same length and their ends perpendicular to their axes and thus parallel with each other. This is not hard to do in a lathe that is in good condition. (My preference would be to use stock that is accurately turned or ground on the outside diameter and the held in a collet.) Once the the plates are bolted together permanently (locktite?) and welded, if that option is taken, a permanent assembly is created. (If welded, I would do a stress relief heat treatment before final machining.)
I lean toward machining the same concentric outer diameter (OD) one each end plate so that one can more easily indicate off the external surfaces. A lathe or a mill can be used to do the final machining of the end surfaces parallel, but machining bores and counterbores is much easier in a large lathe. Other than being careful to maintain the proper relationships, the machining is not difficult. The necessary mounting holes in the end plates can be laid out by hand and drilled. These bolt holes are clearance holes and should be at least 1/32-inch oversize and can be opened up a little more should that be necessary for assembly. The open nature of this type of adaptor should make it relatively easy to assemble the transmissions on their respective ends. I would use bolts and nuts through clearance holes rather than to use studs or capscrews (defined as bolts that are threaded into the body of an assembly rather than into nuts).
One last thought. This sort of multi-post adaptor may not be strong enough in torsion. A "grannie" type reduction can generate a lot of reaction torque on the housing. Should more stiffness be necessary, one or more plates could be bolted on the sides, bridging the two end plates with at least two bolts in each end. This would require machining a flat surface across the outside diameter of the end plates. If four of these plates were installed, we would be back to a closed adaptor. Pinning these plates would make the entire assembly more rigid. With these last statements, I realize that the closed adaptor has strength advantages if everything can be worked out to allow assembly without access to the interior.
OK, for more of a challenge, could a 3 speed brownie be installed on my '88 diesel, C6 automatic, 4WD ext cab pickup ?
I was thinking of a divorced unit, behind the transfer case. i currently have a 2 piece driveshaft.
Would it shift in Neutral, truck have to be stopped?
royzell, With a divorced setup, everything should work the same for mounting and driving a Brownie, so the only issue is the shifting. Let me start this one step at a time and others can add (or subtract) . . .
On my proposed T-98 4-speed plus 3-speed auxiliary, I ran the numbers and there are only 9 distinctly different gear ratios. The best way to use them was 1-L, 1-D, 1-O, 2D, 2O, 3D, 3O, 4D, 4O (where L, D, & O are low, direct, & over in the auxiliary). The other way would be 1L, 2L, 3L, 4L, 2O, 3D, 3O, 4D, 4O (or something like that) and while it is not as good for a manual trans setup, first three gears are a candidate for use of the auxiliary with an auto. If you put the auxiliary in low, you have a low range that is similar to an auto-4X4 low range. This would let you go up to a speed around 30 to 40 mph (depending on your rear axle ratio) and would be useful around town and off-road when you have a heavy load and steep hills. When you are approaching a highway, you could shift the auxiliary into direct or overdrive at the last stopping point without doing much more than dropping the auto into neutral. This would let you choose your final drive ratio before driving on the highway -- basically you could use direct when hauling/towing and overdrive when running empty.
Shifting on the fly would be a bit more of a challenge. I have never tried this combination of auto plus non-synchronized auxiliary, so the following is speculation. I think shifting while rolling could be done, but it would be almost the level of skill and knowledge of one's vehicle that the truckers use when shifting their non-synchro Roadrangers & other transmissions without using the clutch. This old-time trucker practice is still very much alive, but it requires that the driver be able to sense the exact time to shift while using the throttle to bring the engine rpm to the correct point to match the rotational speeds of the gears involved in the shift. Most people would not want this much challenge, but I think it could be done.
Using the first method of shifting (only shifting the auxiliary when stationary) still brings two major advantages:
1) It provides the ability to pre-select one of two final drive ratios for highway.
2) It provides extra torque for maneuvering a heavy load at slow speeds, with the ability to go up to in-town speeds.
It does not provide for easy gear splitting, but the torque converter provides for pretty much the same function.
P.S.: I just noticed that you already have a transfer case (hence 4X4), but the logic of everything I stated does not change other than you would have to stick with direct (for the aux) when in 4WD. You would gain the first advantage above in 2WD, but would only have the second when in 2WD where it would be redundant to low range in the T/C, but in 2WD. If you moved the T/C back and put the auxiliary between it and the auto, you would be able to use more options, including having the ability to have a rock-crawling double low range. (This would be a lot of trouble and chances are that you are not planning on rock-crawling with your long truck.)
Finally, an in-line overdrive will probably give you most of the benefit of using a 3-speed auxiliary at about the same cost and installation difficulties. A Gear Vendors overdrive on the back of your auto would be what I would consider.
Thanks, I used to drive semi's and most of the time shift without the clutch while rolling, so who know's ?
I think the way to go would be selecting ranges and letting the tranny shift, not try splitting gears.
I agree that I would love to have a gear vendors, I just came across this unit for $200, shift linkages and connecting shafts included (which would need to be modified). I figure that the cost of changing the rear driveshaft would be about the same as for a GV. The extra install costs would be the metal work to mount the extra shifter.
royzell, $200 is a good price for any functioning auxiliary. Do you know what model it is? You will want to find out what ratios your proposed box provides. Much of this "Brownie" thread so far has been about the Spicer 5831 three-speed, which is technically not made by Brown-Lipe, but the Brownie designation came to be used to describe all auxiliary boxes before most of us were born.
Regarding the actual shifter, any three-speed floor shifter conversion unit could be used and finding one on eBay should be easy. (Actually a 4-speed shifter should work fine as long as the reverse lever was tied away from the gate position -- that is what I plan on doing with a Hurst Competition Plus shifter that I have should I acquire an auxiliary box.) I plan on using direct links made of thin-wall electrical tubing with appropriate ends welded on. For a more indirect and/or distant mount, cables could be used between the shifter and the box's shift rails.
If you have a two-piece rear driveshaft, the auxiliary box will go in the middle replacing the carrier bearing. The carrier bearing cross-member could be used to locate the front (or rear) of the box with another light custom cross-member locating the other end of the box. Ideally you would keep the aux box shafting exactly parallel with the T/C shafting, but shifted enough to give the front shaft U-joints at least an angle of "exercise" motion. The rear shaft would have, of course, larger angles of operation. The nice thing is that the shafts can be shortened to suit, but I would consider keeping the whole two-piece original setup and just buying a junkyard pair of driveshafts to shorten (& install with new U-joints). This would allow a quick return to the original setup for whatever reason. Both the "new" drveshafts will probably need to have slip joints in them anyway.
Hi, and thanks for keeping the info coming. I know someone who is parting out a diesel 4WD, I could get the spare driveshafts cheap.
This unit is an 8031G. it has about 20% over, direct, and 25% under - I'm told.
I don't know the weight yet, but dimensions are 18"tall, 32" long, 14" wide with 25" wide mounts.
This may have been from a bigger truck, I'm trying to learn more about it.
I was just out on the highway, it would be nice to see those rpm's drop....
royzell, I hope that number rings a bell with someone -- I do not recognize it, but it gets a lot of hits on a Google search for "Spicer 8031". From the dimensions it is probably a heavy-duty box meaning a lot of weight. Unlike the deep-low, direct, overdrive, these ratios are pretty fine jumps, suitable for gear splitting. With your auto, this would give you a choice of three final drive ratios should you choose to only shift when not moving. If you want do do a little clutchless shifting, it would give you a nice split above and below all three gears -- you could just "float" 25% up or 20% down, keeping the diesel in the middle of its torque curve. This type of shifting should be much easier when the jumps are small ones. With your T/C, you really do not need one more "grannie" gear.
Most auxiliary transmissions were in medium and heavy duty trucks. Very few were intended for anything under 1-1/2 ton. The exception that I know of was the true Brownie (made by Brown-Lipe) that my Dad had in his 1951 F-1. It was a little two-speed that was designed to be installed as either an over or under -- stretching my memory, it was 22%. If I could find one right now, I would be happy to put it behind the NP-541 5-speed in my F-350, but everyone seems to agree that these 60-year old boxes are getting pretty rare.
P.S.: Factoid from another forum: At some point Spicer bought Brown Lipe, so the distinction between Brownies and Spicer boxes is blurry at best. (In 1922 GM bought all outstanding shares of Brown Lipe stock, but they probably spun them off to Spicer later on. Please correct any errors as these factoids are from single sources.) Add another keyword for Brownies: Watson. They also became a part of Spicer's auxiliary "stable".
This unit is a model 8031G.
Ratios I've found for it are 1.29:1, 1:1, and .84:1
However, I just did what I should have done in the first place and measured under my truck.
The dimensions of this unit are 18' tall, 32" long and 14" wide with 25" wide supports. I don't know the weight yet but I would surmise that this came from a big truck. It is simply too big for my pickup.
I still like the idea though, a 5831 or other, smaller unit may turn up.
And thanks also to you royzell, for contributing to this thread. I (& others, I hope) enjoy doing the "mind experiment" of working out these sorts of deals. Last night I found a fair bunch of similar threads on Brownies in other forums (e.g.: IH trucks). I posted a few bits I thought were interesting, but one thing that came across several different times was that the heavy duty auxiliaries were just too big for light-duty sized trucks. (Even my F-350 is considered a light truck by these standards.) A 5831 usually went into a medium duty truck and is still a lot of cast iron to add to a light duty truck that still has a full sized transmission.
I do not think anyone has posted a weight on the 5831 yet, so let me hazard a guess that it would be over 200 pounds by the time you added a cross-member and shifting linkage. At 400+ pounds, the Roadranger RT-6610 I plan on putting in my F-350 is still probably not much heavier than the NP-540 currently installed plus an auxiliary. I have recently decided to stick with my original plan to install one big transmission rather than search for the elusive Brownie that is still in perfect shape.
Now that will not mean that I will lose interest in Brownies and other strange (& wonderful) transmissions. One I am still marveling over was in Mac trucks 50 years ago. It was a twin-stick job, but had the auxiliary gears in the rear section of the same cast iron case that the main gears were in. Each section had four gears and the radios were carefully worked out so that there were 16 speeds in a near perfect geometric progression. The exact order of shifting the twin sticks was not a simple thing to remember.
From one internet source (a Mack truck forum): the 5XXX Spicer auxiliaries are 500 ft-lb torque capacity and the 8XXX are 800 ft-lb. This is a similar model number structure to Eaton/Fuller's, so it does make some sense. What bothers me a little is that the aux box is not seeing engine torque, but at least three times as much when the front box is in a low gear. My answer is that the torque rating is continuous where the low gear uses are in short bursts with a lot of shifting time to allow oil to move around.
David, I have not installed a 3-speed Brownie, but I have given it some thought. I think that any 3-speed floor-shift conversion shifter should be adaptable to a 3-speed Brownie. The 5831 auxiliaries are rail shifted and all that would be necessary is to connect the shifter to the front ends of the rails. The shift pattern would be the standard "H" pattern without reverse. I was even thinking of using a Hurst Competition Plus shifter I had by tying the reverse lever forward so that it be out of alignment with the neutral gate. You could mount the shifter on a bracket on the main trans or a bracket on the floor.
If any one sees a reason that this would not work, please correct my thinking.
I Have Looked At Those And Agree Yhat They Would Probably Work. A Friend Found A Closed Shifter That He Used On A Suburban With A 5831 For Od That Worked Well. No Mfg Data On That One So That Is Whty I Am Asking Here. Can Any One Help? Thanks, David