OVERDRIVE - BOLT ON - AFTER MARKET

[devildog80]

Thread for general information as I had the thought to find one for my rig.

Overdrive unit available (for hiway OD only-which is what I want) bolts on back of the existing TC, requires a new rear only drive shaft, and turns the 727 3-speed into a 6-speed.

The bolt on unit electronically shifts in manual or auto shift mode with 1/2 gear increments, to the full gear shift of the auto trans.

So your 3-speed will shift like this
1 to 1-1/2 to 2 to 2-1/2 to 3 to 3-1/2

This is the site for Dodge 727 3-speed info
Dodge 3-Speed Auto - Gearvendors

Go here for more info-
info@gearvendors.com

Looks like the bolt on unit is right at $3200, then need shorter rear drive shaft, as unit is about 12" thick.

Best part about it, they have an exchange program so when you change vehicles, you get credit for exchange to different unit.

Units handle up to 1200 hp, then need hydraulic modification up to 2000 hp.

Looks promising....just need to find those money tree seeds and get that sucker growing

Honestly....would rather spend this kind of money for an O/D unit, rather than FI.

[SJTD]

I'm all for gadgets but how about a 4spd auto?

And for that money you could prolly get a modern motor to go with it.

[tgreese]

I'm all for gadgets but how about a 4spd auto?

And for that money you could prolly get a modern motor to go with it.

Yes.

[devildog80]

Could be, but I do not know, so out here for input.

[Johnzi10]

Looks cool to me! Much less intimidating than LS swap

[dodgerammit]

Yeah, I'm at $4000 for my LS swap and everything needed for it.

Also, with 3.31s the OD is gonna be useless. To take advantage of OD with these rigs and STOCK tires, you'll need a bare minimum of 3.55s with 3.73 being realistic. If you're rocking larger tires, then 4.10s would be preferred.

[devildog80]

You do not think the 1/2 gear shifting would be a positive?

I am not so much looking at top cruising rpm range, but the 1/2 gear increment shifting it does all the way from starting off in 1st, is the appeal for me to check into it further. Pulling hills with camper in tow, truck loaded, and be able to keep up with the fast lane.....that is my goal.

Or is there a solid 4-6 speed transmission I could replace my 727 with, for less than this O/D unit?

Yeah, I'm at $4000 for my LS swap and everything needed for it.

Also, with 3.31s the OD is gonna be useless. To take advantage of OD with these rigs and STOCK tires, you'll need a bare minimum of 3.55s with 3.73 being realistic. If you're rocking larger tires, then 4.10s would be preferred.

[rocklaurence]

Ive looked at that unit and it takes up a lot of space. Its much better to have the OD between the Trans and the Tcase because you end up with a much more compact unit. They do make a unit that is between the Trans and Tcase but its custom order only. Considering the cost and what you get, Id go with a 700R4. Its about the same cost and has more options.

[dodgerammit]

You do not think the 1/2 gear shifting would be a positive?

I am not so much looking at top cruising rpm range, but the 1/2 gear increment shifting it does all the way from starting off in 1st, is the appeal for me to check into it further. Pulling hills with camper in tow, truck loaded, and be able to keep up with the fast lane.....that is my goal.

Or is there a solid 4-6 speed transmission I could replace my 727 with, for less than this O/D unit?

I'd worry about using 4wd and that thing not be disabled and screwing something up in the transfer case. A 700r4 can be adapted and you don't have to worry about the OD being after the transfer case. If you're worried about towing capability more than using it as a final OD, then just regear.

You can also do both and you don't have to eat all of it at one time. ie: regear, then look for an OD.

FWIW, the adapeter WITH required flexplate is $400. https://www.advanceadapters.com/cart

A core transmission is $150ish at the local yard. A good shop should be able to rebuild for about $1200 if you're doing the install.

Rock a GM case for simplicity since the OD is gonna change the shaft lengths regardless. Tom woods can make the shafts. If you're not lifted high and wheeling hard, you won't even need to worry about a slip yoke eliminator.

Either the gearvendors or the OD conversion is probably going to interfere with the stock fuel tank, though I've seen some get lucky without having to move the tank with an OD trans.

Question, have you driven the rig to develop a baseline of how it performs currently while towing? 401s are reputed to be very torquey for their time. Have you ran your info through the grimm jeeper gear ratio calculator to see where the rpms will be running at differing speeds?

[devildog80]

No have not been able to drive it yet, as was working to get it running after sitting 18 yrs from PO, then summer temps here in AZ kicked in!

So doing some thinkin' in the mean time, looking at what others are doing to their rigs to make them better for tasks at hand, and gleaning information to consider or eliminate when I get to the point of deciding IF I will need to do anything at all.

As the 401 and 727 are both time tested and a solid combination, for what I want to do with the truck, might work just fine as is.

All the above info sure helps, as I have never gone into a build this deep, mostly just bought vehicles and drove them, then only fixing what was needed to continue using as is.

Rocking the 700r4 is looking to be the best possibility, for initial shifting improvement (if needed), then regear (again if needed) to follow.

My GW has 4" high arc springs, and I intend to go no bigger on tires than 31x10.5's, but considering to even stay with stock size.

I want the truck primarily for a weekend warrior vehicle pulling our camper, hauling our gear, and only light trails. No intention to off road it past light use to see nature, not to overcome it!

When I do get it road ready with the new tires rolling, have had a chance to hook up and pull a few hills, will then plug in data to see what works best on the gearing.

No intention to frustrate anyone, with me just throwing stuff out there, and not working on anything right now. Just looking for good or bad info on different systems, and know what to save for when the time comes to make changes.

Thanks everyone

[will e]

I run a gear vendors in my Mustang. Most of the time I just use it for the OD but you can do half shifts with it and it would be helpful to find a better gear when trailering up hill in our jeeps.

It has a 4wd lock out so it won't engage if the truck is in 4wd. This is electronically controlled, and I believe the default is 'allow engagement unless I get a signal that the transfer case is in 4wd" so it's not fool proof.

It adds length to the drivetrain but you might still have a long enough drive shaft for driving/4 wheeling. it might also interfere with the coffin gas tanks.

It wouldn't be my first choice for my rig.

[dodgerammit]

You're not frustrating anyone.

I'd recommend making sure the 401 will be what you want. It may be just right as is and fuel economy (or lack thereof) will mean nothing to you..

If it suits you and just needs a little help pulling hills, then go for the GV.

You may find the 3.31s with larger than stock (235/75-15) tires is too gutless to get out of it's own way(my $$ is on that one ) and you decide to regear.

You may absolutely hate the mileage or find some other reason you're dissatisfied with the current engine and want something more modern.

Definitely get a baseline impression of what you like/don't like vs how you want to use the rig.

I too prefer to find running vehicles and modify/repair as I go, keeping them in functioning shape with minimal downtime. I did this with mine for about 4 years before getting the tired, original motor rebuilt (and effed up) by a local shop. Went with the LS based truck engine, installed it myself, and never looked back. Sure, some people b!+c# about my decision, but in the end, the only one who needs to be happy is myself. And I'm damn happy with it. Others have commented how I'm smiling whenever they see me driving the Jeep, so I guess I'm pretty content with the way it went.

[devildog80]

Smiles by the mile is most important

Thanks