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Flipped D300 theory / question
- Thread starter EndlessMtnFab
- Start date
arse_sidewards
Contrary to everything
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- May 19, 2020
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Meanwhile on the Dana 24.Here is a fix someone on the old board did to hold their caps in place:
That would be pretty easy to replicate.
To make it a little cleaner, I'd make a flat plate that is drilled for an interference fit with the caps. No bends, just one flat plate with the caps sticking through. Chamfer the case holes and an o-ring compressed by the plate for a little more clamping force or maybe epoxy the caps into the plate.
VintageSmoke
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- 38
I have been thinking about this for a while. Having been a Harley mechanic for years, I am well versed in leaky shafts LOL. I also happened to notice that the D300 shift rails are very similar to Harley shifter shafts. I never measured the D300 shafts to see if the diameter was close to any of the available Harley shafts, but my "visual memory" says they are at least close.
Harley shifter shafts use a very thin wall brass/bronze bushing that gets pressed into the trans case or cover then gets reamed/honed to size. There is a special tool for reaming, but 25 years ago when I replaced my first bushing on my first bike an old time Harley mechanic who had been in business since the 70's taught me a trick. Tape a piece of fine emory to a wooden dowel and put it in a drill. Use it to sand/ream out the new bushing. If you go slow, use plenty of WD40, and use the shaft as a go/no go gauge you can actually be pretty precise with sizing the bushing. I wouldn't do it for a precision high speed rotational bushing, but for a simple support bushing it's just fine. In this case setting up/getting the feel for an expanding reamer probably wouldn't be worth the effort and finding a rigid reamer specifically for your size of bushing and shaft would be hard or at the very least cost prohibitive. 25 years later I own the special dedicated "shifter shaft bushing reamer" because it speeds up the process, but the same wooden dowel is still in my "special tools" draw. I will say that wear had to be pretty excessive to necessitate changing the shifter shaft bushing and I didn't find it necessary to change many of them.
I will say that Harley uses(or at least used to use) brass/bronze bushings on a lot of stuff like shifter shafts, transmission gears, and even output sprocket shafts which are sealed. Shifter shafts and output shafts also see a lot of side loading. Having a sloppy bushing doesn't generally cause enough movement cause a leak itself unless it's REALLY bad since the seal is flexible, but the wiggle/misalignment of the shaft in a loose bore does cause the seal to wear prematurely. On the older Harley transmissions I wouldn't warranty output shaft seal replacement unless the customer sprung for replacing the bushing which unfortunately meant a complete transmission tear down/rebuild and was usually their last resort after trying to replace the seal at least once.
Honestly though...unless there is a LOT of wear to the shaft and/or bore, causing an excessive amount of radial shaft movement(as in enough to make the shaft lose contact with the seal), I don't see bushing the shaft as doing much to stop/prevent leaks since the shaft doesn't spin and sees minimal side loading. I would look more at seal quality(double lip vs single lip) and quantity. I know people have come up with ways to stack 2 stock shaft seals on the D300. My plan (when i get to my D300 build) has always been to see if I could find a seal with the correct ID/OD, but thinner so I could stack 2 or even 3 seals on top of each other. Some of the Harley shifter shaft seals are very thin(under 1/8") and I often wondered if any of them crossed over.
As to shaft material, Stainless tends to be relatively soft and gummy compared to carbon steel which means it galls easily and isn't very wear resistant. I would be worried about a stainless shaft wearing quickly at the detents unless it was a particularly hard (or hardened) alloy of stainless.
I'm not sure if any of this info answers your question, but hopefully it provides you with some insight.
Harley shifter shafts use a very thin wall brass/bronze bushing that gets pressed into the trans case or cover then gets reamed/honed to size. There is a special tool for reaming, but 25 years ago when I replaced my first bushing on my first bike an old time Harley mechanic who had been in business since the 70's taught me a trick. Tape a piece of fine emory to a wooden dowel and put it in a drill. Use it to sand/ream out the new bushing. If you go slow, use plenty of WD40, and use the shaft as a go/no go gauge you can actually be pretty precise with sizing the bushing. I wouldn't do it for a precision high speed rotational bushing, but for a simple support bushing it's just fine. In this case setting up/getting the feel for an expanding reamer probably wouldn't be worth the effort and finding a rigid reamer specifically for your size of bushing and shaft would be hard or at the very least cost prohibitive. 25 years later I own the special dedicated "shifter shaft bushing reamer" because it speeds up the process, but the same wooden dowel is still in my "special tools" draw. I will say that wear had to be pretty excessive to necessitate changing the shifter shaft bushing and I didn't find it necessary to change many of them.
I will say that Harley uses(or at least used to use) brass/bronze bushings on a lot of stuff like shifter shafts, transmission gears, and even output sprocket shafts which are sealed. Shifter shafts and output shafts also see a lot of side loading. Having a sloppy bushing doesn't generally cause enough movement cause a leak itself unless it's REALLY bad since the seal is flexible, but the wiggle/misalignment of the shaft in a loose bore does cause the seal to wear prematurely. On the older Harley transmissions I wouldn't warranty output shaft seal replacement unless the customer sprung for replacing the bushing which unfortunately meant a complete transmission tear down/rebuild and was usually their last resort after trying to replace the seal at least once.
Honestly though...unless there is a LOT of wear to the shaft and/or bore, causing an excessive amount of radial shaft movement(as in enough to make the shaft lose contact with the seal), I don't see bushing the shaft as doing much to stop/prevent leaks since the shaft doesn't spin and sees minimal side loading. I would look more at seal quality(double lip vs single lip) and quantity. I know people have come up with ways to stack 2 stock shaft seals on the D300. My plan (when i get to my D300 build) has always been to see if I could find a seal with the correct ID/OD, but thinner so I could stack 2 or even 3 seals on top of each other. Some of the Harley shifter shaft seals are very thin(under 1/8") and I often wondered if any of them crossed over.
As to shaft material, Stainless tends to be relatively soft and gummy compared to carbon steel which means it galls easily and isn't very wear resistant. I would be worried about a stainless shaft wearing quickly at the detents unless it was a particularly hard (or hardened) alloy of stainless.
I'm not sure if any of this info answers your question, but hopefully it provides you with some insight.
EndlessMtnFab
Well-known member
VS ..... Lotta good points & points to address!
I always thought leaks were a factory option for Harleys.
My first reason for the brass/bronze guide was for oil control. Tighter tolerances mean less oil is likely work its way to the seal in the first place. A good example would be the earlier NP231/242 transfercases. Occasionally, one would come across a leak out the tailcone. First ... the condition of the slip yoke was verified. If good, the was replaced. If it leaked again, there was a bushing in the housing that would get replaced. If it wore, it allowed more yoke movement and oil would slip past (more than the seal itself could hold back). Then the world wised up and the slip yoke eliminator come into being.
That's where the logic for my idea comes from. Certainly, it doesn't hurt to have less lateral movement (less chance of un-intended fork movement).Agreed on the galling issues. My own stainless working experience is what lead me to think the brass/bronze would have less issues than stainless & aluminum. I don't know if the 17-4 (heat treated) that JB uses is the definitive answer. It would be stronger, for sure. But the reduced corrosion resistance, compared to other grades of stainless, has me thinking twice. I don't mind putting some time or money into the D300, as it will probably suffice for a while. When the money tree blooms (who the fuck am I kidding) ... then I can look at the aftermarket cases. And most of the parts can be moved over (output, gears, etc). More money long term? Perhaps. But it lets me get started now -- so to speak.
That said ... the Nitronic 50 and/or Nitronic 60 shafts represent a good possible rail replacement. Carbon steel strength. Better than 3XX stainless corrosion. More gall resistant. With a price to match, of course. Talking $120 or so for 2 feet (1 foot per rail, rougly). Add the machining cost to that.
Thinner seals make sense. I wonder how easily a groove can be machined into the shift rail housing. Get an X shaped "o-ring" in there.
Now watch ..... I seal that up .... and it starts leaking from an area I've never had leak before.
Tech Tim
Your AD Here....
The Nitronic series is pretty cool stuff, but I'm curious, why the push for SS?
Now watch ..... I seal that up .... and it starts leaking from an area I've never had leak before.
LoL, isn't that the way it always is?
EndlessMtnFab
Well-known member
Because I saw how beat up the "exposed" end of my current D300 rails are. And, of course, the now clean (but still pitted) shaft slides into the O-ring seals in the front bearing retainer. So I put 2 and 2 together. And came up with .... um .. TWO. 🤓
This sorry excuse for a state (PA) uses road salt and a urea/brine spray. Some things are unavoidable. But where i can improve or safeguard --- I'm going to try.
So I have to tear into the case again. Not a big deal. Beats having seals wear out in short order due to a rough rail/shaft.
And I think that's why machines are called "her/she" ---- finicky things.
Semi on topic, how much gear lube or oil are you running in flipped configuration? I assume it needs to be a different quantity than non-flipped?
Also, now that I’m saying that, have you tried different fluids to see if something thicker might leak less?
Also, now that I’m saying that, have you tried different fluids to see if something thicker might leak less?
vetteboy79
It's bent. #ttb
I always just stuffed whatever 85W-140 I could find, and put the fluid level somewhere around the bottom of the mainshaft gears. I feel like that ended up being right about where the old drain plug was, but I might be remembering that wrong.
Interesting thing, when mine locked up after that cap fell out, it was the low range gear that friction welded itself to the front output that then blew the front diff apart. This is the bearing race for the front output and the amount of oil that was left in the case when I got to take it apart. The rear output (32-spline), input bearing, all that stuff was still in fine shape well above where the oil had drained down to. Makes me think these cases do a fine job of getting oil up to the top parts even when flipped, to the point where the bottom runs dry before the top if you get a critical leak.
It took every bit of my 20-ton press to get that gear off the front output shaft.
EndlessMtnFab
Well-known member
Personally .... I was going to try synthetic straight weight motor oil.
*edit Have used regular straight motor oil with no issues.
*edit Have used regular straight motor oil with no issues.
RTH
Offroad addict
Ran a flipped 300 for 5 years and the shifter seals were never the issue with mine. As long as the shift rails aren't pitted and corroded the seals did their job fine. NOW, Drilling and tapping the detent ports, along with the 4wd ports, for NPT plugs (with Teflon tape AND pipe sealant) were my biggest takeaways. Whether your 300 is flipped or not this should be a main thing people do or maybe they've always done it.
Obviously, you'll have to relocate the breather, i used the drain plug on my inspection cover
Obviously, you'll have to relocate the breather, i used the drain plug on my inspection cover
EndlessMtnFab
Well-known member
My shafts are less than stellar (as I mentioned about the brine & salt).
I did drill & tap my detents. Forget what chemical i used to seal them up with. Haven't done anything with the NPT for the 4wd ports (yet). Right now it's on the back burner .... but I need to look into the rails a bit more. The three of us are sick at the moment .... so I'm not doing shit.
I did drill & tap my detents. Forget what chemical i used to seal them up with. Haven't done anything with the NPT for the 4wd ports (yet). Right now it's on the back burner .... but I need to look into the rails a bit more. The three of us are sick at the moment .... so I'm not doing shit.
RTH
Offroad addict
I hear yuh
You can pickup new rails online. I picked up a set from jb custom awhile back. I think they still sell em.
Thinking about it today as well, I drilled and tapped a site tube into the back of the case to watch the fluid level for all the same reasons your worried about.
One more thing to think about adding
You can pickup new rails online. I picked up a set from jb custom awhile back. I think they still sell em.
Thinking about it today as well, I drilled and tapped a site tube into the back of the case to watch the fluid level for all the same reasons your worried about.
One more thing to think about adding
RTH
Offroad addict
You have to pull the 2 press in style plugs on the shifter housing to access the pills that control the shift rail position. When you pull the press in plugs, tap and replace with a threaded plug.