Baker OD6 Transmission Install

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Goofball hold a transmission I’ve had my ‘96 Harley Davidson Electra Glide for over three years now. It came with a mild cam, S&S Super E carburetor and Screaming Eagle ignition. I’ve installed an oil cooler, a wide open exhaust and put larger primary jets in the carburetor. The bike has plenty of power and loads of torque, but was constantly champing at the bit during highway speeds (revving too high). The Evolution engine is an air-cooled rig, so I’m mindful how hard I push it. It rarely ever goes in the neighborhood of 4,500 rpms. Feels perfect at 3,150 rpms. Ninety-nine percent of my riding is on the highway where the speed limit is 70 mph. The stock gearing (all things considered) is garbage. Obviously, Harley didn’t intend these bikes to roll faster than 70 mph. With the stock setup I was doing 75 mph with the engine spinning at 3,176 rpms. With another gear (sixth) with an overdrive of .86 I would be cruising at 87.2 mph at the same rpm, or 2,731 rpms doing 75mph. With the traffic flow between 75-80 mph I was in serious danger because I was going too slow constantly. The engine spinning high revolutions was putting my throttle hand to sleep and making my shifting leg completely numb.

Harley Davidson Baker Transmission So I searched to find a solution. I discovered there are a few companies out there making them, but I found that Baker had the best warranty and reputation, so the choice was easy. I dished out the money and got me the Baker OD6 with the additional one quart pan. It was suggested to me many times to get the Baker DD6, but that would limit my future tune-ability. Reason? The DD6 has the exact same gearing as the stock transmission. First gear on the OD6 is really a super super low gear, well below the stock first. The overdrive from the DD6 is achieved through the use a higher tooth count engine compensating sprocket (using a 28 instead of the stock 25). Then the six gear (which was identical to the fifth on the stock) becomes over-driven. So like I said, the reason was because I wanted a true overdrive transmission and the ability for easy fine tuning later. For example, I still have the choice of screwing with the compensating sprocket, clutch sprocket, rear sprocket, or the front pulley sprocket.

Over the winter after much procrastination and parts gathering I pulled the bike in the shed and tore it down. The tear down was quick and easy, like they always are. Without a lift this would be an impossible swap. Also, unless competent with tools and repairs it’s not even worth trying. Using the service manual for this job was a must. Hands down the hardest part of the install was getting the transmission in (sounds stupid I know). The fit was so tight I was really doubting it would happen (next time I might remove the engine). I think because I got the additional one quart pan, but am not sure. I had the engine jacked up, the swing arm out of the way and everything else cleared out too. After what seemed like hours and hundreds of attempts I got it in with the help of the wife (sounds dirty, but it’s my wife… not a girlfriend). When talking about it over dinner that night I was still bitching and complaining how hard the fit was. The wife corrected me and said it took eight attempts and 30 minutes! Not too bad… . I was just damn nervous because I didn’t want to put one single mark on this high dollar hunk of metal- which I did not!

Baker sixth gear over drive transmissionWhile I had it all apart I rebuilt the clutch, replaced the inner primary bearing and seal, installed a new primary chain, and replaced all oil lines (fill, return, breather). I also decided to restrict my exhaust a bit because I don’t have baffles and was being robbed of some torque downstairs. I ended up installing some torque cones. They are basically a smaller than exhaust diameter orifice cone that sandwiches between the head and exhaust and restricts the flow a bit. Getting it all back together was a snap because I took my time. Once I had everything all bolted up the last thing to do was install the oil lines. I figured I wouldn’t need factory molded lines (I was ⅔ right). The breather and the fill I just used bulk hose and it did all the necessary bends no problem. The return hose proved to be a bitch and I was forced to order the molded hose from Harley. So there I was with the bike all bolted up and a 4” hose is keeping me from riding! I tried all kind of shit to fabricate something up. Short of removing the metal section of plumbing and running a bastard setup I opted just to wait. To make matters worse a buddy at work had just purchased a bike and was rubbing the shit in daily!

Sixth GearFinally the hose came in and two days later I received a second one (ordered two). With all the fluids topped off and a nervous feeling in the back of my mind I started it up on the rack to look and listen. Everything seemed fine, so I lowered it and took it out for the maiden voyage around the neighborhood. There were no problems whatsoever, but I was not able to get into sixth because of the roads. I came back to the house and told the wife I was going to make the circle (a test drive routine I do which is about 20 miles). Informed her of the direction I would be going and to come get my ass if I’m not back in an hour. Also told her where all the life insurance paperwork is. When I got on the open road and heel clicked that Baker into sixth I was one happy dude, let me tell you.

Baker six speed transmissionAt first I topped the tranny off with Spectro 75W-140 full synthetic and was hearing a wine noise in 5th and 6th gear. I called James up over at Baker and he told me it was normal, but if it bothered me to use Redline Heavy Shock Proof 75W250. I ended up draining the Spectro and filling it back up with Redline. The first thing I noticed with the Redline oil was that it is super slippery. I’ll explain: When I get to the bottom of the mountain I live on I come up to a large main road that shoots back up the other side of my mountain. Normally when shooting up the mountain side (moderate throttle) I can’t get going fast enough to get into sixth (overdrive) gear. With the Redline oil I got there no problem. I do not intent on running the Redline oil when the weather cools off though, but for the summer it’s staying.


Harley DavidsonThis transmission has exceeded my expectations and is well worth the price and labor. With every click into each gear the precision of the transmission can be felt, very short throw. It is almost impossible to mis-shift (between 1-2). The top three gears are extremely smooth. The bike has a much more pleasant feel to it now. It is absolutely awesome on the highway between 75-85 mph and that is exactly what I wanted. I’ve gone from being constantly overtaken on the highway to either holding my own, or overtaking. The bike has to really be moving to want to be in sixth though. I’ve had the bike on the road for two weeks now and have put about 700 miles on it.


rear viewOrder the return oil line way in advance because it will take two weeks to arrive (factory ordered only). Be prepared to cut half an inch from the exhaust bracket that mounts to the front of the tranny, or you can order a pre-cut one from Baker (will need ½ longer allen bolts too). If you have a race brace you will no longer be able to use it. The Baker tranny sticks out about ½ more than the stock unit. Additionally, you will need to find the stock cam cover bolts to put back on (if you had to remove the race brace).


Crank locking step thingy, offset wrench for clutch adjusting bolt, small press for the inner primary bearing, clutch spring compression tool, motorcycle lift, 1-1/2 socket for the engine sprocket, and torque wrench just to name the main ones.Baker Over Drive parts necessary










Gear Ratios:

BAKER RPM vs. Speed Calculator







Throw it in the Woods!


    • You dawg!

      Assume you’re not selling the new transmission?

      Wow… $2k for a used/tired Harley engine! No wonder I like Japanese bikes…..

      • Hell no I ain’t selling that tranny. That was part of the master plan! I think I can get around $1,600 for the engine and $300 or so for the carb, then I also have the ignition too. It will be somewhere just under 2k, I think. Engine should be here on Wednesday. Ordering a new front motor mount, some plug wires, and a new stator/charging system so all is fresh. I think the swap should be a snap.

        • Awesome!

          You are going to have a great package there. Nothing like a fresh motor… except maybe a fresh motor with a new OD transmission!

          Hey, we may have our bikes up and running around the same time. I got two of the jugs installed last night; the third one goes on today, if I can find a little time. Then it’s almost ready to install in the frame. Still have a few cables to get and hook-up, but it’s nearly there….

    • Dom, that’s an awesome motor and all, but my parent’s house with 1.5 acres in rural Tidewater Virginia only cost $6000… of course that was in 1960…but still…

      Congrats on the new motor, that is sweet!

      • I was gonna say.. Because I’ve looked at homes in Tidewater, Norfolk, Virginia Beach, Suffolk, and a few other spots before I moved up here. I am selling off a few things to rationalize the purchase, of course. Letting a 1996 Sportster go, selling the old engine, and a few other odds and ends. So it’s not like I am forking over that in cash. More like form shifting the material I already have! lol

  1. I’ve been thinking about doing a similar swap/upgrade to my ’83 Honda Gl650. Its V-twin has a much higher RPM range than your HD (redline is 9,000) and it was built to “rev” – but I still don’t especially like how hard the engine seems to be working at highway speeds around 75 MPH, where it’s taching 5,000-plus RPM. My problem is that there’s not much of an aftermarket for my one-year-only bike (and its long-out-of-production V-twin).

    I wonder whether it would be technically/practically possible to have a custom fifth gear machined? (As opposed to replacing the entire transmission, as you’ve done.)

    I’d love to cut down my RPMs in 5th/top gear by 500-700 RPM.

    It’s the one thing I’d like to “fix” about my bike!

    • If you think you can handle all the gears stepped up a bit (including first) I would try to just replace the front/rear sprocket. Wait, you have a shaft unit. Hmmm.. I need to look at a diagram. That is not even an option is it?


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