Possible Overdrive Setup

[Coyote Patrol]

Im confused Ok good luck with this, i really hope it works out. It would be a nice feature.

[jwgreen]

Im confused Ok good luck with this, i really hope it works out. It would be a nice feature.

Yeah sorry, it's probably my fault. I had found someone who is willing to take a setup up to Global but was keeping it to myself till it actually came through because the last time I said that someone was taking one up there it feel through, but then folks started talking about pooling money to ship one and I didn't want it to get outta control so I mentioned that someone is taking one up in the near future. Again until that happens I will with hold the name of the person just in case it falls through but I'm pretty sure it will work out this time. If it does fall through again, then we can explore the option of shipping and pooling money. Sorry if I confused everyone.

[Mr. Zero]

Justin,

Any updates on this? I'm definitely in on a group buy if this comes together.

[jwgreen]

Justin,

Any updates on this? I'm definitely in on a group buy if this comes together.

There's been some delay with getting the stuff up to the guy in Canada but I believe it will get up there at some point in the future. Then we shall see from there.

[krc65tan]

I know I'm a bit late to the party, but I find the idea of a bolt-on overdrive fascinating! Anyone get any further on this issue? My father-in-law and I just picked up an overdrive for his 50's military Jeep. I was having a hard time wrapping my head around how exactly it worked until I had one in my hand. His Dana 18 transfer case is setup very similar to the Patrol's and his new overdrive bolts where the rear PTO would normally go. The overdrive has a planetary gear within that (when engaged) converts direct drive 1:1 to 1:.78, increasing his top end, but also giving him twice as many gears all around to drive the front and rear axles. Example: He has a 4-speed trans. with a two-speed transfer case and overdrive, which gives him a total of 16 forward speeds (4x2x2) and four reverse speeds (2x2) that can be used for various road conditions. The bolt pattern is not the same as a Patrol, so that's out. Old Land Rover overdrive units look more correct for a stock Patrol application. Am I beating a dead horse with this one???

[krc65tan]

This style overdrive is essentially a two-speed gearbox added to the back of the transfer case. When engaged, power travels through the middle of the overdrive to the planetary, then to the outer gear back through the transfer case gears.

http://hermtheoverdriveguy.com/overdrive-barrel-gear

This is a link to images of a Dana 18 overdrive. If only Nissan had the same bolt pattern!

[jwgreen]

Krc65tan,

The land rover units do not have the correct bolt pattern either. My plan was to send a trans/transfer case up to the guy who makes them and see how he could adapt one for us. Unfortunately I could never get anyone to follow through with taking one up to him and he lost interest in helping me last time I contacted him. So now someone will have to buy one of the Land Rover units and have the mods made to make it work, if it would work at all? Land Rover units are about $2500 bucks if I recall.

I plan on getting around to this project one of these days, but life has really slowed down things on my front for these type of projects. Hopefully one day soon I will be able to start taking on things like this once again.

[desertrat]

Krc65tan,

The land rover units do not have the correct bolt pattern either. My plan was to send a trans/transfer case up to the guy who makes them and see how he could adapt one for us. Unfortunately I could never get anyone to follow through with taking one up to him and he lost interest in helping me last time I contacted him. So now someone will have to buy one of the Land Rover units and have the mods made to make it work, if it would work at all? Land Rover units are about $2500 bucks if I recall.

I plan on getting around to this project one of these days, but life has really slowed down things on my front for these type of projects. Hopefully one day soon I will be able to start taking on things like this once again.

Been working on this myself too.

The Fairy/Roamer overdrive is really a knockoff of the original Warn Overdrive. Advance Adapters is currently producing the Warn type and even those are limited production I believe at this time. Making the gearbox fit would be the easy part, simple aluminum sand casting. It's making the bowl gear that replaces the trans output gear would be the difficult part. You would have to have a bowl gear for the Patrol made. Big bucks there and would need an order large enough to make it happen.

One option I considered would be to use the Dana 18 case (what the Warn was made to fit) and then only a spline adaptation would be needed. The Warn is 6 spline and the Patrol is 10 spline. The Patrol T-case being a Dana 18 design makes things a bit more compatible for conversion than the Rover/Fairy/Roamer OD set up. Toyota and Rover always sit down and decide the most complicated way to make something and then build it. Thankfully Nissan just copied Dana for their axles and t-case.

I haven't given up on this project but it's a big cost just to be able to cruise more than 65mph. 70 and above the stability of my Patrol goes out the window. So I don't really need or want more road speed. There are plenty of times though that I would like to use the overdrive as splitter between 2nd low range and 1st high range. Again not a big deal once you get the hang of split shifting the t-case between ranges on the fly, something only the Dana 18 and Patrol t-case do nicely. Lower t-case gears would be nice too. 1st low is a bit high for driving in the rocks.