When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
A post a long time ago talked about gearing rear axle higher so granny gear becomes first, fourth gear becomes overdrive. You would lose load hauling capacity though.
Depending on what your intended use is and current rear axle ratio, you may also consider a taller rear axle.
I dont think I have seen where the GV could be mounted "divorced" they were all bolted to the transmission with a short tail housing adapter.
Dave ----
I had to dig for it--listed in their "Restoration/Classic" section as "Remote open shaft". OP would have to call them and discuss what he wanted to do.
Of course, it would be a large dollar choice......
Well what do you know
I guess I did not see as I was not looking for one as I had a NP435 or a T18 and they bolt to the transmission.
I know GV is big bucks as I was looking for a OD add on.
Besides the $$$$ it really did not work the way I wanted it to work and went with Advance Adapter unit.
Sorry to say I got 1 of the last AA ones just as Covid hit and they no longer make them
I have heard of some getting lucky to find used GV and AA over drive units but are pretty hard to come by.
I dont know if I would ant to change the gear ratio and then drive a granny 4sp starting in granny 1st?
Also could you get a ratio that low?
I have a 2.75 in the truck and have a 2.47if I want for a Ford 9"
With my over drive and 2.75 gear I have a 1.98 final ratio the 300 six loved it
Dave ----
I do not see the T 98 specifically listed for a GV adapter. We do see the T 19 listed, no idea if it is the same adapter kit . It appears a phone call to GV is necessary to see if a adapter kit is really exists and available for the T 98. IF not, would like to see them offer a direct bolt on to the very common T 98. I would like to see much more info on the remote open shaft option. GV doesn't say much, what type of brackets are included for the installation etc., they could be losing alot of sales opportunities for keeping this option hush hush.
I'm interested in an overdrive for my 1957 C600 COE 272. It has the 2 speed rear axle.
One thought I randomly had reading this thread... yes, you could make the high gear taller in the axle (losing hauling capacity), but is a 3 speed rear axle a thing? Seems like that would be ideal if so?
Assuming not, then I'd have to go for a more add-on kind of overdrive. Does anyone have any experience doing this? What units work well for this?
I'm interested in an overdrive for my 1957 C600 COE 272. It has the 2 speed rear axle.
One thought I randomly had reading this thread... yes, you could make the high gear taller in the axle (losing hauling capacity), but is a 3 speed rear axle a thing? Seems like that would be ideal if so?
Assuming not, then I'd have to go for a more add-on kind of overdrive. Does anyone have any experience doing this? What units work well for this?
Thanks,
Tim
There are no 3 speed rear axles.
You could hunt down a different axle center section for your two speed with a slightly taller ratio. I do not see anything taller than your 5.83 listed in the MPC for '57-'63, so you might be looking at bringing an entire axle over from a later truck.
In the day, people would put an auxiliary transmission in these trucks. Offered as an OEM option in some trucks, a lot were installed in the field. Search "Spicer auxiliary transmission" or "brownie transmission" for more.
GV says they can handle up to 26,000 GVWR. They are said to have a weakness when in reverse, or won't reverse in high range--I'm not clear.
I'm not sure what your planned use, load and trip details are, but I think you will find you are horsepower limited on speed. Grabbing another gear might allow you to cruise more comfortably at a lower speed, but increasing top speed will be a tall order.
The way I under stand the GV over drive works islike a auto transmission and why you have to be going over 30 MPH I think it is for the pump to build up the PSI needed to shift to OD.
If you can be going faster than 30 MPH backing up you are good but I would guess that is why the GV will not go into OD when backing up.
I dont know what is out there for auxiliary transmission that would give you over drive.
Then you would need to figure out how to shift it as I think they would have a stick like any manual transmission has.
I have "twin stick" in my 81 F100 w/300 six - NP435 granny first 4sp and Advance Adapter over drive. (no longer made )
I can split all gears at any speed but some ratios are too close when empty it dose not pay to split.
Works out pretty good splitting other than granny when pulling a 20' enclosed trailer.
Yes I had to cut a hole for the OD stick to come thru.
The GV OD is just a switch you flip to turn on / off for over drive, just run wires is all.
Dave ----
What are my Overdrive Options on our 58 F250 with T98 4 speed transmission?
Another option, but like looking for a needle in a haystack. Find a K code trans in a pre '64 1 1/2 ton or 2 ton. Lot of leg work, but some of the trucks come up for sale cheap as mechanic specials. Sometimes you have to buy the whole truck for just the trans. Example from the past.1962 F500 Dump Truck - Ford Truck Enthusiasts Forums (ford-trucks.com)
