Screwball auxiliary trans idea of the day.

RLDSL · Nov 19, 2007

I've been wanting to get an overdrive for my truck with a zf5, 2wd ,which limits my options to gearvendors.
I like my 4.10 rear for pulling the 5er out of a hole, but would like a few in between gears and a nice cruising gear when running empty.

So, has anyone played around with any of the 3 or 4 speed auxiliary transmissions like the spicer 5831, 8035, 8345, or something real **** like a Spicer Airmatic 9441 A, b or c ?

Something with either under direct and over or double under direct and over, or even a 4 that can be reversed to get under direct over and double over

Air shift would be nice, but I bet those units start getting heavy, and I cut my teeth on big trucks with two sticks, so that wouldn't be a big deal as far as drivability.

If it would be workable, there are a few distinct advantages, like no worries about how much I'm towing, no problems with low speed or decel operation like the GV units ( I've never had a GV per se, but I've had a number of Volvos with Laycock units so I'm familiar with the operation, the problems...and having to rebuild the things )
And having the extra low for pulling and especially for reverse would be real sweet, the reverse on the zf5 is really way too tall when loaded down, even with the 4.10 rear

Big advantage is used and rebuilt units are fairly plentiful, and cost for a rebuilt unit with a core charge would be about the same price as what a used GV goes for once you gather all the parts to make them work. and unlike a GV, if it crapped out in the middle of nowhere, it wouldn't be a big deal to find a spicer service shop.

I know theres a few guys out there who play with the big toys daily. Any thoughts on this......or do I just need to go take some medication :cheers:

Thanks--------Robert

JPR · Nov 19, 2007

Here is info on the Spicer 5831. Woodie did it, here is a picture.

MIDNIGHT RIDER · Nov 19, 2007

Laying in my shop floor, patiently awaiting the accumulation of a few more key items, one being a shifter, is a Spicer 9041(I think?).

Divorced unit with double-under, under, direct, and over-drive; that, coupled with my 5-speed, will yield twenty forward gears and four reverses. ;Sweet

My Getrag is also somewhat quicker in reverse than I would prefer; also, there is a bad hill, or two, that some extra low gears would be nice.

I need to quit procrastinating and get this unit installed.

Where can I get a shifter ??

I think it fastens to the housing of the existing transmission, linking to the shift-rods via stirrup-adjusters and threaded rod.

MIDNIGHT RIDER · Nov 19, 2007

JPR said:
Woodie did it, here is a picture.

That looks exactly like my unit, except my unit is 4-speed. :thumbsup:

How can I PM, or otherwise contact, this WOODIE character ??

Are there more pictures ??

Thanks.

RLDSL · Nov 19, 2007

JPR said:
Here is info on the Spicer 5831. Woodie did it, here is a picture.

Now that's a sweet looking setup ;Sweet

-----Robert

RLDSL · Nov 19, 2007

MIDNIGHT RIDER said:
Laying in my shop floor, patiently awaiting the accumulation of a few more key items, one being a shifter, is a Spicer 9041(I think?).

Divorced unit with double-under, under, direct, and over-drive; that, coupled with my 5-speed, will yield twenty forward gears and four reverses.

My Getrag is also somewhat quicker in reverse than I would prefer; also, there is a bad hill, or two, that some extra low gears would be nice.

I need to quit procrastinating and get this unit installed.

Where can I get a shifter ??

I think it fastens to the housing of the existing transmission, linking to the shift-rods via stirrup-adjusters and threaded rod.

I'd be curious to know the model # for sure of the one you've got, and if you could email any pics?
I'd imagine any aftermarket 4 speed truck shifter setup for rods would work ( actually a 3 speed one would work if you could disable the reverse lockout, it's been so long since I've done an aftermarket shifter, I can't remember how they're setup, but you only need 4 positions, on 2 rods in and out.
I wouldn't buy too nice a shifter since you'll probably have to bend the foo out of it to get it in where you want it. with two sticks, it's mighty handy to be able to reach through the wheel so you can saw both boxes at once and still hang onto things.

--------Robert

h2odrx · Nov 19, 2007

so when I get my 4x4 and it has the zf5 with 4.10's will I want to do this too?

RLDSL · Nov 19, 2007

MIDNIGHT RIDER said:
That looks exactly like my unit, except my unit is 4-speed.

How can I PM, or otherwise contact, this WOODIE character ??

Are there more pictures ??

Thanks.

I've PM'd him, I'll pass along what i find out.

RLDSL · Nov 19, 2007

h2odrx said:
so when I get my 4x4 and it has the zf5 with 4.10's will I want to do this too?

You wouldn't be able to use it in 4wd unless you swapped in a divorced transfer case and rigged the aux box in between, but with r that way, or just for use in 2wd, you could rig one in after the transfer case.

Running a brownie isn't for everyone, learning to shift twin sticks you feel like the one legged man at a butt kicking contest

MIDNIGHT RIDER · Nov 19, 2007

RLDSL said:
I've PM'd him, I'll pass along what i find out.

Thank you.

I have also considered making a simple two-stick shifter, possibly having a locking-pin that locks each shifter in neutral position; this way, I can lock one shifter and use the remaining two gears; then, when I need the other two gears, simply lock the other shifter and use those two.

I could lock the under-drive side, when on the big road, where over-drive would be handy, and lock the direct/over-drive side, when lower gears are called for, such as showing out how slow it will crawl. ;Sweet

One of my main concerns of this install has been that I may need to lose/move a cross-member and the forward fuel-tank.

I got the Cummins/Getrag in; this should be a walk in the park. :thumbsup:

MIDNIGHT RIDER · Nov 19, 2007

RLDSL said:
Running a brownie isn't for everyone, learning to shift twin sticks you feel like the one legged man at a butt kicking contest

Or, you can simply select the wanted range and shift normally.

MIDNIGHT RIDER · Nov 19, 2007

RLDSL said:
I'd be curious to know the model # for sure of the one you've got,
--------Robert

I found this :

http://www.6066gmcguy.org/SM420.htm

Scroll down to the section on auxilliaries for a break-down on ratios.

Listed are transmissions that GMC used and not necessarily all that Spicer offers.

I have the model number and ratios written on something that will take days of digging to find.

I guess it would be easier to read it off the actual unit the next time I am close enough to it.

Seeing that picture of one actually in a truck same model as mine has me so excited that I will not sleep a wink tonight. :peelout

RLDSL · Nov 20, 2007

Dreams of grinding lots of fresh gears down to size

I'm getting pretty jazzed by this idea. I've never been real comfortable with the GV setup idea, and even with my bad habits of overloading things, it would be hard to tear one of those spicer boxes up.
Here's another site with some alternate box specs

It would be pretty cool if I could rig a 4 speed air shift box in there. I drove a big truck with a 5 speed with a 4 speed air shift brownie a bunch of years back and that was a pretty sweet setup. Makes for a quick split exactly where you need it. You do wind up with a few overlapping gears, but the more the merrier.
It drives me nuts on long pulls to be wound out easy in one gear, but not have enough steam to pull the next one It would sure be nice to have a few more in there.

If you went with two sticks for the box locking them out like that, it would make it trickier to split when you need it. 2 sticks can get confusing enough on a long hill, 3 would make things real interesting, and , trust me, once you have those extra gears in there, youre going to want to play with them ;Sweet

---------Robert

flatlander · Nov 20, 2007

MIDNIGHT RIDER said:
Laying in my shop floor, patiently awaiting the accumulation of a few more key items, one being a shifter, is a Spicer 9041(I think?)./QUOTE]

Maybe a 6041? I found one of those in a gmc tandem axle dump truck. I didn't get a price because that's one step farther than I wanted to go (next step beyond that is laying in a puddle removing it and bringing it home.)

Mr_Roboto · Nov 20, 2007

I drove a Ford L8000? with a 5 speed and 4 speed splitter. With that combo at least you didn't have to shift both sticks at one time. I developed a shift pattern where I used something like 11 gear changes.

With the two transmissions there will be different gear combinations that are very near the same ratio, so you don't use all 20 combinations. I.e. 3/2 and 5/1 would be the same effective gearing.

Screwball auxiliary trans idea of the day.

RLDSL

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