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Old 06-27-2012, 03:20 PM   #916
oppozit
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Quote:
Originally Posted by JustinP View Post
That sounds awesome. Has anyone made such a conversion yet? Would love to see more details!
Google Mobec superdrive.
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Old 06-27-2012, 08:30 PM   #917
norton(kel)
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I've got a yamaha/jawa outfit which I just love. I'am hoping to get a Ural to join the stable this year for ADV/Offroad adventures. This thread is encourageing to me because I love having the underdog! Thanks to the naysayers and especially to the guys lifting up the Ural, you all make me want one just that much more
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Old 06-27-2012, 08:53 PM   #918
gspell68
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Quote:
Originally Posted by norton(kel) View Post
I've got a yamaha/jawa outfit which I just love. I'am hoping to get a Ural to join the stable this year for ADV/Offroad adventures. This thread is encourageing to me because I love having the underdog! Thanks to the naysayers and especially to the guys lifting up the Ural, you all make me want one just that much more
In that case, you'll probabaly want a Dnepr...
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Old 06-27-2012, 09:13 PM   #919
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Originally Posted by gspell68 View Post
The closest anyone came to that was the Germans in the 1940's with the no expenses spared off-road Zundapp KS-750 and BMW R-75 rigs.
And ironically they had the same issues with the differential 2wd that Ural and Dnepr did.

Even though the Germans had superior engineering, material and build quality, a post differential driveshaft on a vehicle like a sidecar rig with such a large disparity in load between the 2 drive wheels is problematic, and adding a secondary counter rotating drive shaft compounds the problem. Utilizing CV joints in place of U-joints would help some.

The current Ural 2wd system is technically the most primitive and functionally the most limited, but it is also the strongest, cheapest, and most suitable for the higher speeds the rigs are used at today. Mobec has addressed all the issues a and produces a superior system, but their drive line alone costs more than the most expensive Ural, and a complete rig will be $40k to $60k.

I don't know if it is feasible but it seems to me the current Ural 2wd system could be made full time by replacing the selective shift with a viscous coupler so functionally it would be like a locking differential.
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Old 06-27-2012, 10:25 PM   #920
Midnullarbor
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The viscous coupler at first sounds like a good idea, but what of the long run?

These things have a tendency to deteriorate, and either lose the viscous fluid . . . or go the other way and kind of "lock up" [in which case you would want the selective shift anyway].
In addition, the steering on dry bitumen, and especially on wet bitumen, might prove rather dodgy (though careful tuning of the viscosity could perhaps reduce most of the problem).

I suspect that the current system is about as good as it gets, for rugged simplicity & effectiveness.
But would be nice if the final drive could be modified to give power take-off on the other [left] side as well, for the [admittedly smaller market] lefties.

Either way, one alternative would be a 1500 watt [2 hp] electric motor in the sidecar wheel, designed to give thrust at low speeds (up to say 10 or 15 mph). A decently large battery in the sidecar would provide some useful ballast, and give perhaps 20 or 30 seconds of thrust, to get the rig up and running from a sandy or muddy resting site ~ or up a short section of difficult low-traction slope. This would probably be enough for 99% of off-roading, unless you were traversing persistently Cob-like heavy terrain.
Cost effectiveness? Dunno.
But if Ural were not doing it, then maybe an aftermarket manufacturer might find sufficiently large sales (once you include all the non-Ural outfits that it might be fitted to as well).
Recharge time for the drive battery, might be as little as 5 minutes (assuming a cheap starter-type battery, dropping no further than about 80% charge).
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Old 06-28-2012, 12:03 AM   #921
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Quote:
Originally Posted by windmill View Post
And ironically they had the same issues with the differential 2wd that Ural and Dnepr did.

Even though the Germans had superior engineering, material and build quality, a post differential driveshaft on a vehicle like a sidecar rig with such a large disparity in load between the 2 drive wheels is problematic, and adding a secondary counter rotating drive shaft compounds the problem. Utilizing CV joints in place of U-joints would help some.

The current Ural 2wd system is technically the most primitive and functionally the most limited, but it is also the strongest, cheapest, and most suitable for the higher speeds the rigs are used at today. Mobec has addressed all the issues a and produces a superior system, but their drive line alone costs more than the most expensive Ural, and a complete rig will be $40k to $60k.

I don't know if it is feasible but it seems to me the current Ural 2wd system could be made full time by replacing the selective shift with a viscous coupler so functionally it would be like a locking differential.
I think that Ural just took the cheapest and easiest way out when they replaced the Sportsman type 2WD with the current one.

At the moment, I think the best option for the money (while they're still relatively available) is the MB-750 type Dnepr 2WD that also locks (I saw one on eBay recently for $699). You get the best of both worlds: a full-time 2WD rig that doesn't yaw at road speeds when accelerating/decelerating and that can still be locked when the off-roading gets really rough and the hack wheel starts to slip when your hack load is too light.

I imagine that some of the German's problems came from the lack of a swingarm on either the R-75 or the KS-750. I think a 2WD on a hardtail would be harsh.
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Old 06-28-2012, 01:19 AM   #922
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Quote:
Originally Posted by gspell68 View Post
I imagine that some of the German's problems came from the lack of a swingarm on either the R-75 or the KS-750. I think a 2WD on a hardtail would be harsh.
Not in my experience with the KS750. The two wheel drive system uses a locking diff and a high and low ratio gearbox. In the sidecar the wheel is suspended on a split torsion tube to the sidecar wheel reduction hub. So approx 60% drive is to the pusher wheel, 40% to the sidecar. Except of course when you lock the diff.

Every year the main German parts vendor runs a week long tour in the Spanish Pyrenees, most of it off-road.

http://www.youtube.com/watch?v=mpTRIHcQF1w

Interestingly a lot of new made replica parts are available, including complete rear diffs, sidecar wheel reduction hubs and most parts to make an R75...........

Best

David
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Old 06-28-2012, 07:54 AM   #923
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Quote:
Originally Posted by oppozit View Post
Google Mobec superdrive.
Mobec price from another hack forum:

"Mobec Superdrive with axle steering, 2WD, reverse, reduction (Latinos call it pig's gear) (if I remember right there is a hydraulic differential available too) = 24.000 Euro = 31.400 $ WITHOUT the bike nor freight nor taxes.....
From the bike is nearly nothing left, just seat, engine and fairing.
The whole thing is like a solid platform you screw under your bike's main frame.
Its not a bike with a side car, but a 3 wheeled platform with a bike's heart."

Don't know if that is accurate or not, sure is a lot of moola!!
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Old 06-28-2012, 08:16 AM   #924
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Mr. Cob wrote: So what it all comes down to is this, if I want to TRASH and ABUSE a rig in serious sometimes stupid off road rides the Ural is the weapon of choice hands down; on the other hand if I want to ride 2,000 miles to get someplace on a hacked rig and I need or want to be there in two to three days the Beemer is the only reasonable way to go. Different tools for different tasks, it really is the only way to go.
Dirty Dr wrote:
I guess you finally got me to put a post in this mess. I have always liked sidecars but I didn't buy my first one until 2006 when I bought the Patrol new. I bought it for the main purpose of riding all Winter up here since I couldn't ride my 2 wheelers for 4 or 5 months out of the year because of the snow. I love the Ural and I have abused that rig on the mountain passes and in Moab and such to the point that I can not believe that it has put up with all of the abuse and still runs. I still consider it as trustworthy as any motorcycle I have ever owned and still ride it regularly.
That said it also convinced me to hack the GS and as you know that has become my long distance weapon of choice.

Thesea re two guys who deal with teh best of both worlds. I think the debate here is a little silly in that it does , to a point , compare apples to oranges. Urals are great where they are great. The larger big bore adventure outfits are great where they are great and the smaller bore dual sport outfits seem to bridge the gap in some ways. All are fun. and all have their place. Urals are Urals as soemoen said.
Urals are cool but not as much of a gas and go machine sometimes as some.
So, you pays your money and you deals with what you have. Threads liek this can be productive for one just starting out as they can provide some good info. Remembering that good news never travels as fast as bad is important though. I like them all and will continue to do so.
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Old 06-28-2012, 08:38 AM   #925
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Quote:
Originally Posted by gspell68 View Post
I think that Ural just took the cheapest and easiest way out when they replaced the Sportsman type 2WD with the current one.
As opposed to the most expensive and most complicated.
A lot of folks are already balking at the price of a new Ural, and that the FD's are not as robust as they could be. It was probably a very wise decision to not use a system that would be significantly more expensive and more prone to failure.

Sometimes the simplest answer is the best overall answer. KISS.

For my money, I rather have a creeper gear than a more complicated drive line.
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Old 06-28-2012, 10:30 AM   #926
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Quote:
Originally Posted by windmill View Post
As opposed to the most expensive and most complicated.
A lot of folks are already balking at the price of a new Ural, and that the FD's are not as robust as they could be. It was probably a very wise decision to not use a system that would be significantly more expensive and more prone to failure.

Sometimes the simplest answer is the best overall answer. KISS.

For my money, I rather have a creeper gear than a more complicated drive line.
True. I'm not really knocking them for doing what they probably had to do to keep the brand (or at least the 2WD model lines) alive. It's just...disappointing. I'm certain that it wasn't a decision that was made lightly and a lot of consideration went into it. Actually, it was probably the Western Europeans and Americans driving styles that prompted the change as well. The current 2WD setup allows for near 1WD fuel efficiency on road and the better 2WD traction option off-road. The major advantage of the full-time 2WD setup would be the hard-ball handling and highway traction in the snow, but was slightly slower and sucked down more gas.

I agree about the need for an "off-road" gear. I don't know if it was a factory gearbox, but I think it was Leszak in Poland had a Dneprmatic gearbox that was geared for off-road use. I wonder sometimes, too, if a 1940's BMW R-75 "gelande" gearbox is similar enough to bolt up to a Ural/Dnepr without getting the 4 reverse gears effect.
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Old 06-28-2012, 11:11 AM   #927
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I like them all and will continue to do so.
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Old 06-28-2012, 11:43 AM   #928
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As an ex-Sportsman full-time 2WD owner I will testify that the system is more useful as a novelty than as a practical affair. Sure, it's cool when you can let go of the bars and have the rig track perfectly straight as the sidecar gets 30% of the power and pulls its own weight, but off-road the open differential is actually worse than a 1WD, and you can't fly the chair.

It seems almost purpose-built for doing donuts in a snowy parking lot, however
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Old 06-28-2012, 12:02 PM   #929
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Quote:
Originally Posted by eastbloc View Post
As an ex-Sportsman full-time 2WD owner I will testify that the system is more useful as a novelty than as a practical affair. Sure, it's cool when you can let go of the bars and have the rig track perfectly straight as the sidecar gets 30% of the power and pulls its own weight, but off-road the open differential is actually worse than a 1WD, and you can't fly the chair.

It seems almost purpose-built for doing donuts in a snowy parking lot, however
Howdy eastbloc,

Thanks for this information. I often fly the chair when riding off road, I pick the best path for the bike itself and least damaging path for the sidecar. I will often fly the hack over mud holes, rocks and or ruts, doing this with the Sportsman type final drive would be extremely difficult if not impossible.

The other bad thing about an "open" differential is that ALL power will be delivered to the wheel with the LEAST traction in slippery situations, this means that when you need power to the pusher the most it would often be delivered to the sidecar wheel making matters even worse then as you have pointed out you only had one wheel drive to begin with.
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Old 06-28-2012, 12:30 PM   #930
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Originally Posted by gspell68 View Post
True. I'm not really knocking them for doing what they probably had to do to keep the brand (or at least the 2WD model lines) alive. It's just...disappointing. I'm certain that it wasn't a decision that was made lightly and a lot of consideration went into it. Actually, it was probably the Western Europeans and Americans driving styles that prompted the change as well. The current 2WD setup allows for near 1WD fuel efficiency on road and the better 2WD traction option off-road. The major advantage of the full-time 2WD setup would be the hard-ball handling and highway traction in the snow, but was slightly slower and sucked down more gas.

I agree about the need for an "off-road" gear. I don't know if it was a factory gearbox, but I think it was Leszak in Poland had a Dneprmatic gearbox that was geared for off-road use. I wonder sometimes, too, if a 1940's BMW R-75 "gelande" gearbox is similar enough to bolt up to a Ural/Dnepr without getting the 4 reverse gears effect.
What was the details on the "1940's BMW R-75 "gelande" gearbox"? I googled it and couldn't find any info on it, just curious about what it was??
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