Diesel Dnepr on chain drive

[numuzmar]

one of my friends decided to build a Diesel bike he had an old Dnepr, so its obviously a good start, sort of
He has a opinion that Dnepr final drive reducer is a problematic unit (I agree with that) so bye bye to the shaft.
clutch is automatic and centrifugal, from some kind chinese scooter, no test drive yet so I don't know how that clutch will work

[Tetronator]

the Dnepr final drive is problematic, how so?
I'm thinking of using a Dnepr because its an shaft drive.

Interesting solution tough!

[numuzmar]

Dnepr shaft is one of sources of vibrations, rubber damper also commonly have huge dis balance, that causes leakage from gear box, and do I have to mention if you have a leakage from reducer you stay without rear brakes, hear me right, IMHO its good when you have bigger engine or you ride with sidecar, I say its not that bad and you can deal with that problems but its way simpler to deal with quality chain

[Tetronator]

So the problem lies in the fact that;
Both Drive shaft and rubber damper in the gearbox are so imbalanced, that they break the seals of the final drive on the rear wheel?

If I were to balance/build a new drive shaft rubber coupling combination would that fix the final drive issue?
Having brakes is important, arguably the most important part of the bike.
Not having brakes due too leaky final drive isn't nice...

[bf109v7]

Nice job, I like it.
But to Dnepr final drive. You can get rubber dampers of better quality now, since 3 years. And the shaft seal is not resistend against hypoid oil, but it works fine with ordinary gear oil. But some people mean well and put in the expensive staff. And there is a small hole, so, if the seal should leak it the oil will go to the outside and not into the brake. This hole must be kept kleen, abd there are people who forget to do this. And last not least: The gear weels are not of very good quality, but they are cheap, and right insalled, they do the job. BMW parts fit, but the are very expensive.
Alex

[Tetronator]

Just to be sure, we are talking about this part (the rubber damper);
http://www.ural-zentrale.de/product_inf ... -ring.html
Which isn't balanced enough and thus causes a lot of vibrations?

And if I just use normal gear oil in the final drive it should be fine?

[bf109v7]

For havens sake, no. I was talking about parts you could get from him: http://www.moto-moscow.de/
The disk is not meant for centering or balancing the drive shaft, the shaft should center in the hole of the gearbox output shaft.
And yes, normal gear oil is good for the final drive, if you want, you can add Molikote. But the additives of hypoidoil make a sticky mass out of the oil seal.
Alex

[Tetronator]

Hmm, then I'm confused as to where the problem lies exactly.

This is the gearbox output;


The rubber damper/flexible coupling goes over the 2 pegs;


The the driveshaft pegs go into the remaining 2 holes.


And I tougth the vibrations stem from the rubber damper/flexible coupling.

[bf109v7]

Hmm, then I'm confused as to where the problem lies exactly.

This is the gearbox output;


The rubber damper/flexible coupling goes over the 2 pegs;


The the driveshaft pegs go into the remaining 2 holes.


And I tougth the vibrations stem from the rubber damper/flexible coupling.

Correct so far. But the the driveshaft goes thru the drive shaft peg and with its ball shaped end into the hole of the gearbox output shaft. Or was it the other way ruond, I don't have the parts here. Could be that the gearbos output shas a ball shaped end and the drive shaft has the hole. In any case, the is a centering device there. But, I saw also parts where it was cut off, by somebody who did not understand why its there.
Alex

[Tetronator]

This is the 'leaky seal oil drain hole' you talked about earlier I think.


I think I see what you mean, the 'middle peg'of the 3 pegs on the gearbox output.


Which inserts into a hole on the end of the driveshaft. (Of which I cannot find a picture.)


I still do not know what causes the vibrations then... Imbalance in the driveshaft?

[bf109v7]

This is the 'leaky seal oil drain hole' you talked about earlier I think.


I still do not know what causes the vibrations then... Imbalance in the driveshaft?

I saw Universal joints which were not realy in line. Did you check this?
And I can see a picture adress only when I go on quote, it is not coming in your post. But I can not load any picture.
myural.com does not open
Alex

[Tetronator]

This is the 'leaky seal oil drain hole' you talked about earlier I think.


I still do not know what causes the vibrations then... Imbalance in the driveshaft?

I saw Universal joints which were not realy in line. Did you check this?
And I can see a picture adress only when I go on quote, it is not coming in your post. But I can not load any picture.
myural.com does not open
Alex

Hmm, I can see the pictures just fine. Anyone else have the same problem?

No, I haven't checked anything as I do not own a Dnepr or Ural, I'm just treeing to figure out if this is a problem I will have to deal with when I build my diesel bike.
And also if there might be a solution to the problem.

Dnepr shaft is one of sources of vibrations, rubber damper also commonly have huge dis balance, that causes leakage from gear box, and do I have to mention if you have a leakage from reducer you stay without rear brakes, hear me right, IMHO its good when you have bigger engine or you ride with sidecar, I say its not that bad and you can deal with that problems but its way simpler to deal with quality chain

Acording to numuzmar, the shaft and rubber dampers cause a lot of vibrations due to having a huge imbalance which causes the gearbox/final drive to start leaking oil. The oil coming out of the final drive will leak onto the rear brakes and cause them to not work.

So I'm treeing to figure out where the problem stems from and if there might be a solution for it.

[mark_in_manchester]

My Ural-Daihatsu 993 turbo works fine - 50+bhp (compared to ~33 stock on a good day), loads of torque, 90mph top speed and no gearbox / FD problems yet (though fitting the 3.2:1 modified bevel set was / is a big pain in the arse). I added a bit of bent-over tube to the Ural FD filler plug as an additional breather, as the factory breather vents into the drum (!), albeit in a manner which is not 'supposed' to coat the shoes in oil. It seems to work. If you have a Dnepr FD the breather is under a plastic mushroom somewhere near the top and external, so this should also work fine.

[Tetronator]

My Ural-Daihatsu 993 turbo works fine - 50+bhp (compared to ~33 stock on a good day), loads of torque, 90mph top speed and no gearbox / FD problems yet (though fitting the 3.2:1 modified bevel set was / is a big pain in the arse).

Nice, doubt mine will produce as much. Put many miles on it yet?

How was fitting the modified bevel set hard? Because I'd like to do the same, I heard it required some machining of the FD.

I added a bit of bent-over tube to the Ural FD filler plug as an additional breather, as the factory breather vents into the drum (!), albeit in a manner which is not 'supposed' to coat the shoes in oil. It seems to work. If you have a Dnepr FD the breather is under a plastic mushroom somewhere near the top and external, so this should also work fine.

Does that work? Or is the filler plug lower than the breather hole? Otherwise the oil will still go into the drum, right?

[mark_in_manchester]

>Nice, doubt mine will produce as much. Put many miles on it yet?

Probably 4-5000. Head gasket is gone at the moment and first I had to change the one on the car too, as being more in the family 'critical path'! Slowly looking like I might soon get time to do it.

>How was fitting the modified bevel set hard? Because I'd like to do the same, I heard it required some machining of the FD.

3.2:1 sets used to be cheap from Oldtimer Garage in Poland. Then they were not available - now they are again, but made somewhere expensive I think! The pinion is BIG - too big to go through the hole in the casing it has to fit through. You have to file away the shoulder that the big double-row bearing which the pinion runs in, locates against. Expect to make shims until you get the backlash right between crown wheel and pinion - I'd not have been able to do it without a lathe. I put a post on here somewhere about doing it, in some detail I think - a few years back now.

>Does that work? Or is the filler plug lower than the breather hole? Otherwise the oil will still go into the drum, right?

You're just relieving (gas) pressure, so as to stop an oily mist filling the drum. If you follow the makers instructions and ONLY put enough oil in it to come up to the BOTTOM of the threads on the filler (oh - unlike Ural I think Dnepr give you the luxury of a dip stick!) then liquid oil should not reach the level of the breather, and lack of pressure should mean large oil seal holds oily mist out of brake drum. It seems to work fine for me, and I've run a variety of Ural bikes for about 15 years.

[Tetronator]

>Nice, doubt mine will produce as much. Put many miles on it yet?

Probably 4-5000. Head gasket is gone at the moment and first I had to change the one on the car too, as being more in the family 'critical path'! Slowly looking like I might soon get time to do it.

I see, too much boost? Not really that conclusive then in terms of longevity... Although you are running a way more powerfull engine on it...

>How was fitting the modified bevel set hard? Because I'd like to do the same, I heard it required some machining of the FD.

3.2:1 sets used to be cheap from Oldtimer Garage in Poland. Then they were not available - now they are again, but made somewhere expensive I think! The pinion is BIG - too big to go through the hole in the casing it has to fit through. You have to file away the shoulder that the big double-row bearing which the pinion runs in, locates against. Expect to make shims until you get the backlash right between crown wheel and pinion - I'd not have been able to do it without a lathe. I put a post on here somewhere about doing it, in some detail I think - a few years back now.

Hmm, I cant seem to find the gears.
This is the best one I could find; http://www.oldtimergarage.eu/catalog/pr ... ts_id=3386
Which is 3.4:1, and expensive.

I'll go look for that post of yours. Edit; Found it; https://www.dieselbikeforum.com/view ... 880#p21880

>Does that work? Or is the filler plug lower than the breather hole? Otherwise the oil will still go into the drum, right?

You're just relieving (gas) pressure, so as to stop an oily mist filling the drum. If you follow the makers instructions and ONLY put enough oil in it to come up to the BOTTOM of the threads on the filler (oh - unlike Ural I think Dnepr give you the luxury of a dip stick!) then liquid oil should not reach the level of the breather, and lack of pressure should mean large oil seal holds oily mist out of brake drum. It seems to work fine for me, and I've run a variety of Ural bikes for about 15 years.

I see, then I'd rather just plug the drum hole and go with your solution. Not having brakes is bad...

[mark_in_manchester]

I'd leave that hole open (your finger points to it in one of your pics) since if anything makes it past the seal, that gives it somewhere to go.

Seriously, I'd give it a go before you mess about too much. If it leaks, worry about it then. Ural brakes are never very good at the best of times

[coachgeo]

I'd leave that hole open (your finger points to it in one of your pics) since if anything makes it past the seal, that gives it somewhere to go...

agree.. add a tube to it and plumb that to drip where you need it. Call it a self luber for your chain ?? If you decide to stick with shaft drive after all.. drip it on the CV joint/U Joint?

[Tetronator]

Fair enough, But I have yet to own an Dnepr so no worries yet.

I'll just dump it into the fuel tank the engine wont mind...


Maybe make a little catch canister for it then, so I can pour it back in if needed.

[numuzmar]

https://www.youtube.com/watch?v=6dPodx0VVEk