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Spartan AKA "Blokka" Locker for Nivas ?

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Winch Assistant

Joined: 23 Jan 2010
Odometer: 66
Location: Durban, South Africa

PostPosted: Sun Feb 19, 2017 3:35 pm    Post subject: Spartan AKA "Blokka" Locker for Nivas ? Reply with quote

Has anyone ever tried one of these Spartan type lockers - called "Blokka" lockers from Russia ?

Some details from the supplier:

"BLOKKA for Lada Niva uses a simple method to lock the axles for maximum traction and to unlock them for full differential action, that is as required when cornering or driving on hard surfaces.

LOKKA differential locker

The actual principal of operation while easily demonstrated is difficult to explain in writing - but is as follows.

BLOKKA for Lada Niva has only 4 main parts - a pair of Cam and Axle (side) gears for each axle, some springs and pins, and some have spacers and shafts.
BLOKKA for Lada Niva is normally in a fully locked state and only allows differential action by unlocking the unit when the ground driven force acting on a wheel (either during turning or when negotiating obstacles) forces that wheel to turn faster than the other driven wheel, ie a turning vehicle's wheels actually travel two different paths with the inside wheel turning in one circle while the outside wheel travels in a larger circle, and therefore faster.
BLOKKA for Lada Niva makes use of two distinctly different sets of opposing forces that exist due to its design - one to dynamically engage the gears when engine torque is applied and the other to dis-engage the gears when one wheel overruns.
The locking force is applied by the action of the pinion cross shaft acting on a 4 dimensional spiral cut cam groove with bearing surfaces - the more power applied the harder it locks.
The unlocking action occurs due to the ramping effect between the low profile, almost zero backlash, ramped teeth which force the cam away from the axle gear (against the minor pressure of the bias springs), for example when an outside wheel turns faster than an inside wheel - when cornering. Power continues to be applied to the inside axle. As the turn is completed and the wheels again rotate at the same speed, the outside lock re-engages.
Note: The bias springs can easily be compressed with 2 fingers, resulting in BLOKKA for Lada Niva being able to unlock correctly even on low traction surfaces.
It should be understood that only when there is an external force being applied to a wheel to make it turn faster than the rest of the drive train will BLOKKA for Lada Niva allow one wheel to differentiate. Slippery surfaces where one wheel would normally break traction in an open differential cause LOKKA to stay locked - even with one or both wheels in the air, BLOKKA for Lada Niva will remain locked."

I did quite some reading about Spartan lockers used at other 4x4 vehicles and in general people seem to be very happy with it. There are some downfalls though. Reading this report about Spartan diff behaviour in general, I just thought someone might have tried one of these at a Niva, and might be able to come forward with a review ? :

"As for road manners, it definitely beats the welded hands down on pavement though it does have it's quirks. While going around a sharp corner, the locker does allow the outside tire to overrun the ring gear but only if there is very little torque going into the pinion on the diff. If you are engine braking while turning or if you use too much throttle the Spartan will lock up suddenly and there will be clunking, banging and a tendency to understeer slightly. While testing it's manners, I was engine braking down a very steep and SHARP curving road and the Spartan would get into a cycle where it lock suddenly and the tire would bounce then unlock then lock back up causing a sort of pulsation in the rear axle. This was quite loud and I will try to avoid this like the plague since it CAN'T be good for anything back there. It is worth noting though that this was a very nasty residential street and had VERY sharp corners. If I pushed in the clutch in instead of engine braking everything was fine. As it WILL lock up fully in a turn if you apply too much power, I would notice that when I hit the throttle in a turn I would suddenly get some understeer after it locked, along with the familiar clunk. It also added a little extra play in there that is slightly noticeable while shifting gears, but not a deal breaker. If you learn to use very smooth and minimal throttle while in a sharp turn, it will work perfectly. It also seems to be happier if don't shift gears while in a sharp turn. Some people seem to be concerned with it clicking in a turn, but it's not really very loud. You have to roll down the window, turn down the stereo and really listen for it to hear it. I really couldn't care less about that anyway.

Off road, it's not much different than the welded. It is a VAST improvement in off-road capability over the old open differential, and I would rather burn my truck to the ground than put an open diff back in there. After a couple days, I have learned to adjust my driving style to avoid upsetting the locker in a sharp turn. In my opinion, the benefits of this type of locker far outweigh their flaws. So, all that being said, I am now considering putting one in my front diff too. If I had to do it over again, I would buy another Spartan."

Thanks !
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Winch Assistant

Joined: 23 Jan 2010
Odometer: 66
Location: Durban, South Africa

PostPosted: Fri Jul 21, 2017 3:11 pm    Post subject: Reply with quote

Questions to and answers from Eric Mcvey, a Niva owner from Australia who installed Blokka lockers and a 2WD device at his Niva. I just thought this info might be very informative to interested owners who might stumble across this thread:

Question : Eric how does the Blokka behave when 2x4 has been selected ? To my understanding the Blokka should not lock at all when 2x4 has been selected -because in 2x4 mode the propshaft does not generate any torque at the diff ? In short, does the drivetrain not behave in a weird way by times when 4x2 has been selected ?

P. S. Did you order the Blokka mounted to an inner housing, or did you install a loose Blokka to an inner housing yourself ?

Answer: Hi danie, the front blokka is well behaved in 2x4 mode. It just just free ratchets/clicks in a turn. as you say as long as there is no torque you wouldnt know it is there, i use 140 weight diff oil which significantly dampens the clicking to the point where for me its hard to hear the clicking noise in normal driving, the ladas general noise levels helps drown it out too, Wink . The rear blokka is less civilised on the road, under normal conditions they are ok, but you have to drive to the behavior of the locker, there is more free play on take off and if you lightly engine brake around a sweeping corner, or roundabout you get a "bucking" sensation as the locker switches between driving on the inside and outside wheels. It is easy enough to avoid but would be tiresome if your car was your daily driver, i ran a suzuki jimny for a few years with a lock right in the back and it was ok, but ended up changing it out for a selectable air locker as it was a daily driver car. Also having the front locker in play all the time in 4x4 mode can be a disadvatage in certain circumstances like off camber down hill slopes, but again, you know the characteristic is there and allow for it in th driving technique. For me the niva though is not my everyday car so the trade off is irrelevant compared to the offroad benefits.
There are a lot of jeep wranglers out there who use lock rights, spartans and aussie lockers (LOKKA) in the front without issue in 4x2 mode. The wranglers do not have free wheeling hubs either, so they are working all the time.

I bought the pre setup housing, the reason is when lada went 24 spline they changed the diff housing to allow for a bigger diameter on the side gears, you can buy a version of the Blokka that will slip straight into the old housing but with 24 splines in that version there is less metal around the outside of the splines, so i decided to get the version with the housing which has the bigger diameter side gears.

Many thanks to Eric for sharing this info!
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