Stovebolt.com Forums The Parking Lot Big Bolts Gearing Options for a 3 ton?

Though it is unlikely that I would or even want to, it would still be nice to have the option to take it on the highway. Currently, the few short distances I took on the highway, it felt most comfortable at 70-80 kmh. If I were to take it on longer distances, a minimum of 90 would be better. It is a 1953 GMC 9700 3-ton grain truck with a regular 4-speed manual and 2-speed differential. The engine has been changed to a '66 292. Apart from not having the engine at high RPM, I heard the 292 is already bad enough on fuel.
Apart from completely changing the driveline, are any of these an option:
- Are there any add-on overdrive units available for 3 tons?
- Can a 2-speed diff have the gears changed?
- What higher gear transmissions would work in it?
- Or what rear axles would bolt in?
For the most part, I'm just curious.

Nice truck! A Brownie(Brown Lipe) aux. transmission is somewhat easy to install in the middle of the driveline. A tag on the side lists MN. They are sizes according to ENGINE torque, I e 5531, 550 torque capacity. 6241 600 ft. lbs. torque capacity. Anything larger, 7000 series, would be too large for your truck. Look around in wrecking yards, don’t bother calling, they won’t know what you are talking about, might jack up the price, make sure to get the shift lever assembly from the cab. Shift linkeages are easy to make from water pipe or EMT. Easiest way to ID is to look for add’l shift lever in cab.

Almost all are 3 speed, some are 4 speed, under, direct, OD, corresponding to 3rd number in MN. OD would correspond to shift lever in cab being fwd against firewall, to the right. Most come with Tru-stop disc brakes on the aft end which will replace the existing brake on the rear of your 4 speed. Brake belongs on last location before diff, otherwise if rear trans. is in neutral, no brake. Google ‘Brownie or Brown Lipe’ for ratios. Early one had brass gage, later steel tape. There are no parts. No rear seal, reverse threads keep oil in. All are non-synchro, easy to shift.

Ed

Thank you!

Those transmissions show up on Ebay occasionally- - - -search "Brown-Lipe" or "auxiliary transmission". Ignore the ones for the big rigs like Peterbilt, Kenworth, etc. You'll be looking for the medium duty trucks.
Jerry

Another thanks!
I had forgotten about "brownies".
There is a truck salvage yard just over 100 km from me.
Been wanting to take another trip there, just to look around.

If you find a Brownie, get all the parts, shifter, crossmembers, driveshafts, speedo cable, etc. so another trip would not be required.

Ed

I think I'd do some research on 5th overdrive transmissions. International & other mid-sized trucks came with them. Maybe GMC had them too. Also, it seems to me it'd be easier & cheaper to find a rear differential with ratio you need, or even change out the ring & pinion in your third member than to do the work of installing a 3 way in your truck.

GMC had OD 5 speeds, synchro too, I have one in my ‘54. Nice tranny. Easier to change rear diff, than deal with ring and pinion change, hard part is finding parts and anyone who has them. Changed out 6.5 single speed diff. to 5.39 two speed in same ‘54. Two speed may take different length axles than single speed.

Ed

Ed, nice to see that shortened fire truck in use!
The 5:39 two speed with overdrive 5 speed sounds ideal.
Glad you could get that combination put together.
The crane must be a lot of fun! Are there outriggers on that rig?
C

Outriggers, however I have not used them yet, suspension pretty strong, Don’t plan on any really big loads.

What engine is on your truck, mine is a 503, that works fine with the OD 5 speed. I took 4’ out of the wheelbase, too hard to get in and out of my driveway, had no need for all that length.

Ed