Looking at a Doug Nash overdrive unit for a 3spd auto. That’s how it is described anyway. Wondering if you guys know a way to tell the difference between the over and underdrive models. I have looked up a lot of info. Seems a lot of folks liked em and some didn’t. Any you guys ever use one?
Anthony I gather you are talking a DN5 speed. I never had one but only heard good things about them. There should be some numbers that will identify the trans. Good Luck, Pat
They had a tailshaft unit. I bought a TH400 one and it came with an extra set of gears to go the other way. Have not used it as he said shifter motor was not working. So should be same on outside. Might be able to turn and count in vs out
The auto in my bus is great, would rather install this on the trans rather than install an electronic OD trans. Would be much easier and more economical. I have never messed with these. Seems the weak is the point motor which is usually user error .
No help here Anthony, I have one that fits a C-6, but have never driven it! Don’t hear much about them anymore! Bones
I have one on the shelf. It was behind a t19, but I didn't keep the adapter that went between the transmission and DNE2. Guess it'll sit until I find an adapter. I counted to in vs out revs to determine over vs inderdrive. I dont know of any other way to determine which it is.
It's been a long time, had one in an ot pickup truck some 20 years ago behind a TH400. Worked similar to a gear vendors or us gear unit. Truck is long gone, tranny is still sitting in a deceased buddy's shop. I think I still have the literature for it.
Cool Wonder about stopping. Can it be wired to disengage when you apply the brakes or is that necessary.
I put an underdrive in a customer's step van, after I took out the crazy low gears that it had. Now it has those gears, and a freeway range. The only way I know to tell the difference in to turn the input, and watch the output. The wiring diagram and operation manual is online, somewhere. I will see if I can find it. It cannot be disengaged. You are in one range, or the other range.
The design was bought by US Gear, and they carried it on, for a little while. http://www.dieselwarden.net/temp/usgear/US Gears overdrive manual.pdf http://www.dieselwarden.net/temp/usgear/Dual Range.pdf http://www.dieselwarden.net/temp/usgear/U.S. Gear DR Elec Install.htm http://www.dieselwarden.net/temp/usgear/U.S. Gear DR Elec Troubleshoot.htm
Bought the OD unit. Super clean and smooth. Manual shifted fine. We will se when we install it. Should help the short bus cruise a little better.
Thanks for posting that info Gimp! I will store it away fir future use.... if I ever use my overdrive! Lol Bones
I didn't save the photos but I was looking into an 84 Chevy Dualie crew cab yesterday that had a Doug Nash overdrive/under drive on it. Truck had a 4:11 rear. Engine was bad but the truck was solid and someone beat me to it. Price for the whole thing wouldn't buy the overdrive in most places. I want to replace my current tow rig with a crew cab and that would have been nice but I didn't think my trailer would haul it.
Anthony, these Doug Nash units use some parts that look suspiciously like two speed big truck rear ends. The three bolt shifter motor, the bid where the wires hook up, look the same distance as the points in those big truck two speed shifters. Might check a a truck supply house if you have a problem in that area. Maybe! Bones
Sometimes manufacturers tell you other items won’t work, because they want to sell you their parts. A fire pump company had a pump shifter that used similar, items. This company said truck two speed parts won’t work. They wanted to sell me their $300 shifter motor! I went to the truck parts supply house in my town and got the shifter motor fir $69. Worked perfectly. Sometimes you have to read between the lines! Bones
Delivery truck dropped off a present today. now we can finish up the 500 block. Going to order springs. We figured out the wiring for the OD. And yes, it can be wired like a 2 speed truck rear. The Doug Nash version doesn’t use the “electronic box” the dual range version used. But that’s basically just a 2 second momentary switch anyway.
Yup. My customer with the step van is an electronics wizard, for a tech company. He just whipped up his own controls, in no time flat.
We have an electrical instructor certified in motor controls. He liked this set up. I knew it was simple but I enjoyed watching this guy figure it out. Took about 5 minutes. We’re going to set it up like a two speed axle. Push pull switch on the shifter. 2 small lights on the “dash” for gear indication. Will use a hidden switch to cut power off to the system. That’s just to make sure students don’t mess with it
That one is for a turbo 400. I have two for a C6. Only "one" complete wiring harness and switch. The other harness could be repaired / matched to the complete one but I'm still short one switch. Because of the overall size , I couldn't use it. I had to go with a GV unit and paid through the AXX. All could be bought for $500 + shipping from LA/OC area.
The GVs are high even used, the ones I found were in the 1200-1500 range. I will have half that in this one set up. I paid more for this one than probably it’s worth , but this one was exactly what I needed and in reasonable driving distance and in very good condition. The size isn’t an issue for my bus bat I can see where it could be.
Thanks for the links. I finally hooked it up. Used a 2 speed rear switch and wiring. Worked well. Does have a noticeable “clunk” mostly during disengagement.
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