LSD\'s

[dthebuk]

Just wondering where i can get one for the egi and how much its likely to cost?

am i right in thinking that some TII\'s came with lsds?


cheers

[Jimi_Hendrix]

You are right in thinking some TII\'s came with LSD\'s but i dont know where to get one other than Ebay or the for sale section here.

[dthebuk]

i saw your name and i thought you were gunna take dibs on the first on beeing sold


cheers for the help.

any idea on price?

[m1tch]

Can you not just swap out the FD internals from the diff and fit it into the casing?

[Ricco_04]

Apparantley, yes the FD diff will go into the FC casing and is a good upgrade (I want to do this at some stage)

If you turn one of the wheels should the opposing wheel turn the SAME way or the other way to say you have lsd?

[Jimi_Hendrix]

Different kinds of LSD\'s return different results to the old wheel turning trick. Some will turn the opposite wheel backwards and some will turn it forwards.
 
Best thing to do is get one wheel on a big wet patch (or grass) and the other on dry tarmac then load up a bit and sidestep.
 
If both wheels loose traction then there is no LSD. If the one on the tarmac bites then there is an LSD. At least i think thats how it goes.

[TiddlesRX7]

is it not the other way around? If both wheels spin then there is a LSD. As in a limited amount of slip before the diff bites spinning both wheels. Im sure someone will answer this better than me.

[Prof]

From the Wiki Man:
 
Viscous
The viscous type is generally simpler, it relies on hydrodynamic friction from fluids with high viscosity. Silicone-based oils are often used. Here, a cylindrical chamber of fluid filled with a stack of perforated discs rotates with the normal motion of the output shafts. The inside surface of the chamber is coupled to one of the driveshafts, and the outside coupled to the differential carrier. Half of the discs are connected to the inner, the other half to the outer, alternating inner/outer in the stack. Differential motion forces the interleaved discs to move through the fluid against each other. In some viscous couplings when speed is maintained the fluid will accumulate heat due to friction. This heat will cause the fluid to expand, and expand the coupler causing the discs to be pulled together resulting in a non-viscous plate to plate friction and a dramatic drop in speed difference. This is known as the hump phenomenon and it allows the side of the coupler to gently lock. In contrast to the mechanical type, the limiting action is much softer and more proportional to the slip, and so is easier to cope with for the average driver. New Process Gear used a viscous coupling of the Ferguson style in several of their transfer cases including those used in the AMC Eagle.
Viscous LSDs are less efficient than mechanical types, that is, they "lose" some power. They do not stand up well to abuse. In particular, any sustained load which overheats the silicone results in sudden permanent loss of the differential effect.^[4] They do have the virtue of failing gracefully, reverting to semi-open differential behaviour. Typically a visco-differential that has covered 60,000 miles or more will be functioning largely as an open differential; this is a known weakness of the original Eunos Roadster sports car. The silicone oil is factory sealed in a separate chamber from the gear oil surrounding the rest of the differential. This is not serviceable and when the differential\'s behaviour deteriorates, the VLSD centre is replaced.
 
So our VLSD\'s are probably mostly shot unless they\'ve been serviced or replaced recently.  The Helical Limited Slip Diff in the FD\'s does apparently fit in the FC casing - I am looking at doing this mod next year.  They use the Torsen type helical diff.  It\'s much more predictable, but doesn\'t fail gracefully like the VLSD.
 
Geared LSDs are less prone to wear than the clutch type, but both output shafts have to be loaded to keep the proper torque distribution characteristics. Once an output shaft becomes free (e.g., one driven wheel lifts off the ground; or a summer tire comes over ice while another is on dry tarmac when the car goes uphill), no torque is transmitted to the second shaft and the torque-sensitive differential behaves like an open differential.
Geared LSDs are dependent on the torque and not on the speed difference between the output shafts. Such differentials may not be adequate on extremely slippery surfaces such as ice (or thin air, when a drive wheel loses ground contact altogether) ^[3].
 
So be prepared for tail out situations if you do that modification :Giggle

[AtomicRex]

If you want a Diff built we have Kaaz diffs in stock and would be happy to build one for you.
 
http://www.mazdarotaryclub.com/forums/showthread.php?t=51479

[t2rew]

i have got a fd diff and a compleate t2 axle. yours for 150 quid the pair. the fd internals fit into the fc case. cheapest option.

[dthebuk]

awesome thanks for the info guys.

t2rew, havnt got £150, i thought they\'d be a bit more but you never know, cheers for the offer tho

[Ricco_04]

So the FD diff is Torsen type helical diff so is the FC a Helical Limited Slip diff?

Im just trying to work out wether the diff in my fc is limited slip or not (or half broken lol)  IE : does the opposing wheel turn the same or opposite way when jacked up on LSD FC?

[Prof]

The torsen diffs are LSD\'s, the TII diffs were viscous types - but the fluid may well have been overheated (under load) and hence they then behave like open diffs.  Chances are very few of ours are still operating 100%

[Ricco_04]

Ah ok gotchya - thanks.  Out of interest then do you know which way the opposing wheel turns.

FD diff = better and most likely working too, hell of an upgrade me thinks! :chat

[Prof]

Best I\'ve found is this:
 

You can tell if you\'ve got one if you jack the back end of the car up and turn a wheel by hand. If the opposite wheel turns the same way, it\'s got an LSD. If it turns the other way, it\'s open. Sometimes it helps if you hold the propshaft stationary whilst you do this. And it doesn\'t always work anyway. (1/03)

On a loose surface, put on full lock and drive slowly round in a circle, if you have an LSD the rear tyres will scrub and you will hear it. (1/03)

 
But like it says - it doesn\'t always work.  I know the viscous ones are speed sensitive not torque sensitive, so you may need to move the wheel quicker than would be possible by hand before you see it \'lock up\'.   Although the gravel trick does seem to work