viscous coupling eliminator

tchui

Forum Member
Joined
May 24, 2018
Messages
21
Location
kenya
Car Year
2002
Car Model
forester
Transmission
manual
i did a search but didnt really get what i wanted.


ive built a foz for offroad rallying, on a budget.



it has all open diffs and I have been on the search for LSD's starting with the rear.


I managed to get a plated one and will install it soon.


for my purpose i think the center diff lock up is more important than the front.


here is my question.


the cars with DCCD offer 50 / 50 lock up as the premium setting for gravel.


would a viscous coupler eliminator or a welded center diff not offer the same characteristic?


I believe a locked center diff but open front and rear would handle terribly. bu not that Ive managed to get a rear lsd i want to send more torque to the rear.



a 20kg center is not an option.


but the fact that these exist suggests that totally locked is not the way to go or was that just the best option before DCCD came along?


thoughts?
 
The 5MT DCCD has a 35/65 torque distribution that can be "locked" 50/50. It has been developped for rally racing on all surfaces.

20kg viscous is more of a gravel specialist so it might meet your needs too.

And how are the HotBits doing on the kenyan gravel roads ?
 
something in my head said its not a true 50/50 lock. it needs to be slightly front or rear bias to keep handling. like 49/51 or 51/49.


anyway im probably going to give it a shot. im sure i will find a burnt out unit somewhere to play with.


hot bits hmmm to be honest their a good shock and toh is a great guy but i think im asking a lot from them for what im doing.



i think i posted to make sure one is supplied with longer canisters as the pressure build up is a lot given the extended stroke.


other issue is the shafts are 22mm outer and then hollowed out for rebound adjustment.


ive had a leak due to top cover not being tight enough on assembly and a bent shaft.


bent shaft has not caused a leak yet although its pretty bent, this is the reason I did not go inverted other than price, but now i may have to for the strength.



these issues are due to the overall length of the shocks and the increased lever forces this creates.



Standard length i think toh provides a good economical option for most peoples capability and budget.
 
The 5MT DCCD is a planetary differential that distributes torque 35/65. There is a clutch pack inside that can vary the torque infinitely up to 50/50. Its not a real locker as the clutch can't hold a huge amount of torque but I have never reached the limit offroad, only on dry bitumen making some tight turns at low speed to test the locking of the clutch pack and the engine usually stalls before the slippage occurs.

As for the HotBits, you are probably, as you say, asking a little too much ! Would be interesting to know if the shaft bent after a jump or a lateral shock or just on normal corrugations while driving fast.
 
ive had a suggestion to add a friction plate onto the original 4kg unit.


the bend starts on the shaft at he point of normal ride height / extension. no impacts of any sort. front shock. i run a 00 camber. 215/75/15 rubber and sit id estimate 50mm taller than stock.



https://www.facebook.com/Goodtimes4x4/
 
tchui said:
ive had a suggestion to add a friction plate onto the original 4kg unit.


the bend starts on the shaft at he point of normal ride height / extension. no impacts of any sort. front shock. i run a 00 camber. 215/75/15 rubber and sit id estimate 50mm taller than stock.



https://www.facebook.com/Goodtimes4x4/
Click to expand...

there's a bloke in Aus who refurbs viscous diffs.. you can choose a thicker fluid if desired to get a stiffer diff. I don't think you'll be able to just pop in an extra disc, and its a right mess anyway.

Look up corgiwerx on f***book. He may be able to do your diff, (though shipping would be prohibitive), or maybe give you a lead on the source of diff goop.
 
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Lucas Automotive in Moorabbin, Melbourne, also recondition centre vLSDs.
 
BillyCorgi said:
The 12kg.f and 20kg.f are made using thicker viscosity silicone fluids
Click to expand...

Good news ! This means that its also possible to have better rear Vlsd's as its just matter of silicone viscosity, right ?
 
Interestingly, non-newtonian fluids can become less viscous (eg quicksand) or more viscous (eg cornstarch in water).
A viscous LSD is like cornstarch in water, only it doesn't taste as good!!

This is awesome!!
Fun begins at 1:40min
[ame="https://www.youtube.com/watch?v=RkLn2gR7SyE"]Non-Newtonian Fluid in Slow Motion - The Slow Mo Guys - YouTube[/ame]

Walk on water:
Watch from 2.40min
[ame="https://www.youtube.com/watch?v=JkS1ymQ73oc"]Brainiac Science Abuse-John Tickle Walks on Custard - YouTube[/ame]
 
Last edited by a moderator:
I remember once getting out of trouble in the bush by putting vegetable oil in the brake master cylinder. Does this mean I can also put custard in my centre diff? :rotfl:
 
What happened to BillyCorgi's posts??

Curious...

Cool to know the settings can be messed with if you're willing to play with the "goo".

Cheers

Bennie
 
when i search silicone and cst a commonly used RC option comes up.

interestingly its used in the drivetrain as well! same stuff?
RC drivetrain would not be heating up much so I doubt it.
 
Kevin said:
He's a vendor and I have contacted him to make arrangements to participate as a commercial entity.
Click to expand...

It’s a shame - what he was talking about is very interesting and relevant to this thread.

Cheers

Bennie
 
tchui said:
when i search silicone and cst a commonly used RC option comes up.

interestingly its used in the drivetrain as well! same stuff?
RC drivetrain would not be heating up much so I doubt it.
Click to expand...


Nup - RC drivetrains have huge power densities. Much higher than your average car.


Power to weight is much larger, and I bet any viscous couplings they use have much higher power/volume.



Probably higher power dissipation, but much lower duty cycles (they don't drive for hours).
 
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