1WD vs 2WD Dnepr

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aronbike
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1WD vs 2WD Dnepr

Post by aronbike » Sat Feb 01, 2020 10:43 pm

Dear all,
I want to ask some impression and opinion about the 2WD Dnepr. How is the percentage of failure in mixed-use on-road and off-road?
Nowadays, with current speeds and with current road surfaces, is it still reliable product?

Discussing with some people, was told me that the rear drive is suffering transverse and vertical load coming from the side wheel.
Traverse load are mainly coming when turning on right and the side-wheel push the rear drive through the shaft.
Vertical load are when there is a big gap between rear wheel and side wheel, for example, one wheel go inside a deep pothole at “certain speed”.
All those load are more severe driving on asphalt (more grip) and if the bike speed over 50-60 km/h.
In off-road since the speed are quite low and the ground is softer, the risk is lower.
My mechanic suggest a small modification on the two joint of the shaft to absorb lateral load, adding some coil spring, but for vertical load there is nothing to improve.
In general, he suggested driving very gentle, especially when turn right on artificial bumps and keep speed below 50 km/h, but then I need double time to reach my destination. :wink: :lol:

All those issues are not in 1WD, can drive a bit faster and do not care too much of the road surface. But for sure 1WD is less performance in off-road.
What is your opinion? Have you ever experienced failure of the rear drive in such condition?

Many thanks
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URALNUT60
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Re: 1WD vs 2WD Dnepr

Post by URALNUT60 » Sun Feb 02, 2020 10:00 am

I would direct this towards the 2wd owners and what for fix has been used to alleviate this problem, what part of the country do you live in? I have full time 2wd 650 Ural, no issues on driveline, just the motor, I have a buddy that is completely happy with his 1we 750 Ural, he takes it in some off road conditions, so I guess personal preference, we live in South Central Pa., ask yourself what type of riding are you gonna be doing

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Bilgekeeldave
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Re: 1WD vs 2WD Dnepr

Post by Bilgekeeldave » Sun Feb 02, 2020 11:45 am

I haven't had any issues with my MT-16's final drive. I have taken it off road a few times, but I mostly stay on paved roads.
Dave

RAMCO-Dnepr MT-16

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Re: 1WD vs 2WD Dnepr

Post by ReCycled » Sun Feb 02, 2020 12:26 pm

I am not aware of any real world failure rates that are worse for 2wd vs 1wd Dneprs. That is, other than it is a more complex system with more moving parts.

As far as performance the 1wd does fairly well in the vast majority of situations. The 2wd does however behave better in most conditions. On the street it accelerates straight and tracks better when shifting gears. It does great on plowed but snow covered roads. It also has good traction on dirt and gravel covered roads...BUT;

Its shortcomings are common to all open differentials, it's only as good as its weakest (traction) link. In true off-road situations it is very easy to get stuck simply because the sidecar wheel is spinning and no power is delivered to the pusher. There is also an unpleasant situation on the road when at a stop and trying to turn right sharply and accelerate quickly when the sidecar wheel unweights as it is trying to act as the primary driver.
David B.
'07 Ural Twourist

aronbike
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Re: 1WD vs 2WD Dnepr

Post by aronbike » Sun Feb 02, 2020 2:49 pm

Hi,
I live in Italy. Good to know that in the other side of the world, the European issue and headheach didn't outbreak yet :P
For me is clear more stuff inside more easy to break, I belive keeping lower speed in bumpy road and avoinding pass trough potholes at higher speed should keep safe the rear drive and last longer. Looks like you confirm that.

I want to make a Dnepr MB650 replica, thus I need to install a 2WD. I also collecting information to install a lock differential kit.
If I go to 1WD, I will change a project (maybe K650 or MT-11).

I don't understand how the Dnepr differential works. As far as I know, a open differential from car, if one tire goes up or lose traction it starts to spin and the onther tire with grip instead doesn't move, it doesn't receive tourque. In Dnepr, instead, if one tire goes up, it stops. Seems that Dnepr differential is kind of limited slip differential. Do you confirm that? How it can stuck in deep mud or sand? Usually LSD gives some tourque to the wheel with grip.
Thank you

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propwash
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Re: 1WD vs 2WD Dnepr

Post by propwash » Sun Feb 02, 2020 3:45 pm

It is not limited slip. Lift the sidecar wheel and all power goes to the lifted wheel. The locker solved that.
The geometry of the two models is vastly different. Side car wheel is more aft on a 2wd model and the sidecar sits up higher.
I have time on both models and prefer the 1wd model in virtually all situations.

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Re: 1WD vs 2WD Dnepr

Post by dneprlover » Sun Feb 02, 2020 6:19 pm

I have all 3 types. !wd, 2wd diff and 2wd with diff lock. The most capable all rounder is 1wd with tyres to suit the terrain. Big problem with the 2wd models is traction on the sidecar wheel.

MT16/MB650m1 is pretty good for reliability and your mechanic is talking crap. Phase the shaft correctly according to the manual and they are pretty good. The earlier heavy driveshaft as fitted to MB750/MT12 and MB650 can cause problems due to it's rigidity. Most faults are caused by flying the chair. 2wd Dneprs always run better with weight in there.
Neval BMW/MT11 800cc hybrid, Neval 2wd MT10-36, Neval standard MT10-36, Neval MT16, another MT11, BMW/MB650 hybrid , K750m and an MB750 with locking diff.

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Re: 1WD vs 2WD Dnepr

Post by aronbike » Mon Feb 03, 2020 6:21 am

dneprlover wrote:
Sun Feb 02, 2020 6:19 pm
I have all 3 types. !wd, 2wd diff and 2wd with diff lock. The most capable all rounder is 1wd with tyres to suit the terrain. Big problem with the 2wd models is traction on the sidecar wheel.

MT16/MB650m1 is pretty good for reliability and your mechanic is talking crap. Phase the shaft correctly according to the manual and they are pretty good. The earlier heavy driveshaft as fitted to MB750/MT12 and MB650 can cause problems due to it's rigidity. Most faults are caused by flying the chair. 2wd Dneprs always run better with weight in there.
Hi, any guidelines how to phase the drive shaft correctly? Is there lighter drive shaft could reduce the fail?
Thank you

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Re: 1WD vs 2WD Dnepr

Post by ReCycled » Mon Feb 03, 2020 8:28 am

Lots of info on phasing can be found here using the search function, it's just a matter of keeping the u-joints aligned. The heavy shaft was only found in the earliest 2wd, not much fear of that unless the bike is sidevalve and locking differential
David B.
'07 Ural Twourist

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Re: 1WD vs 2WD Dnepr

Post by dneprlover » Mon Feb 03, 2020 9:54 am

The driveshaft shown in your photos is the later lightweight one. it is pinned into the U/J at the wheel hub end and slides on its splines at the Diff end. This copes with ALL loads quite adequately. Just make sure the diff has 100cc of good oil in each compartment and grease the nipple on the diff U/J when servicing. Get a manual and phase the shaft as it says in there. Make sure the wheel hub has 200cc of good oil in it and cruising on paved roads will be comfortable at 75-80 kph. Don't let the sidecar wheel lift off the floor under any circumstances.
Second thoughts, get a 1wd, it will perform better and you don't have to worry about lifting the sidecar wheel.
third thought. Get a new mechanic. the system has worked well all over the world for over 50 years.
Neval BMW/MT11 800cc hybrid, Neval 2wd MT10-36, Neval standard MT10-36, Neval MT16, another MT11, BMW/MB650 hybrid , K750m and an MB750 with locking diff.

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Re: 1WD vs 2WD Dnepr

Post by aronbike » Mon Feb 03, 2020 12:32 pm

dneprlover wrote:
Mon Feb 03, 2020 9:54 am
The driveshaft shown in your photos is the later lightweight one. it is pinned into the U/J at the wheel hub end and slides on its splines at the Diff end. This copes with ALL loads quite adequately. Just make sure the diff has 100cc of good oil in each compartment and grease the nipple on the diff U/J when servicing. Get a manual and phase the shaft as it says in there. Make sure the wheel hub has 200cc of good oil in it and cruising on paved roads will be comfortable at 75-80 kph. Don't let the sidecar wheel lift off the floor under any circumstances.
Second thoughts, get a 1wd, it will perform better and you don't have to worry about lifting the sidecar wheel.
third thought. Get a new mechanic. the system has worked well all over the world for over 50 years.
The picture of the modification of the joint is from a shop, I post the picture of the drive shat I have to overhaul. I believe it is the smaller one.
I understood the shaft phasing, but if someone of you have a Dnepr manual to share I will appreciate it :cheers:
Before to give up I want to investigate all the potential of 2WD :lol:
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Re: 1WD vs 2WD Dnepr

Post by dneprlover » Mon Feb 03, 2020 2:26 pm

Get a handbook and parts catalogue off Charlie Harvin's site at http://cvkustoms.com/index.html

You have the modern lightweight drive shaft off the MB650M1 or MT16 model

there is a mystique about the performance of 2wd and much of it's praise is by people who have never owned one. the golden rule is to carry weight in the sidecar, especially off road and also that MT16 models have a slightly lower first gear to help with hill starts and climbing

Good luck with it.
Neval BMW/MT11 800cc hybrid, Neval 2wd MT10-36, Neval standard MT10-36, Neval MT16, another MT11, BMW/MB650 hybrid , K750m and an MB750 with locking diff.

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Re: 1WD vs 2WD Dnepr

Post by aronbike » Tue Feb 04, 2020 9:40 pm

We have discussed a lot on cons of 2wd, would you share your experience pro and cons of 1 wd? :clap:

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