Curly wrote:
Sorry to be the harbinger of bad news, but the pictures you posted of the differential are definately not an LSD.
What you have there is what the Americans call a 'Phantom LSD'. It is really a standard 'open' diff that's been modified to incorporate a couple of spring-loaded thrust plates that restrict the motion of the output gears until a enough load is applied to over-ride the spring pressure. Unlike most LSDs this type of diff will still allow the unloaded wheel to spin in conditions where excessive load is applied, such as when applying full throttle in a hairpin bend, or dropping the clutch with one wheel on the dirt and the other on the bitumen.
That's not to say they're no good. On the contrary I have one in each of three non-mini competition/sports cars that I drive and find that they do work quite a lot better than an open diff in getting the power to the ground, and don't suffer the usual driving drawbacks found in some full LSDs. For the price, which is less than 1/2 that of an equivilent LSD, I think that they're pretty good value.
Although, for the record I do run a Quaiffe LSD in my Cooper 'S' because for competition purposes you need all the traction you can get.
Curly, that is a poor attempt at harbinging, but as the name suggests it IS a Limited Slip Differential. ANY LSD does not 100% prevent the differential effect but LIMITS it, it is just a question of how. There are many kinds of LSD, this is a "CONE TYPE" manufactured by Fred Sayers in QLD. As you rightly point out it IS a standard differential modified to LIMIT spinning the unloaded wheel by requiring a huge torque through the diff to will allow one wheel to spin relative to another. I stuck one shaft in a vice and tried to turn the other shaft relative to it. I did not succeed, as i need a much longer lever arm than i had at the time. I discussed this at length with Graham before getting it to stick in this gearbox, and i am very comfortable that it will perform as advertised. Yes under extreme conditions of torque on one wheel is somehow much greater or in the opposite direction to the other side, and if it wears there will be some differential effect. But ask yourself this, if the unloaded wheel is unloaded, how is there going to be a torque applied that will result in overcoming the friction that is applied to the diff gears. The biggest problem with this type of LSD is that it is always "on", so low speed (think tooling around the pits) steering is a tad on the difficult side. As i said, Fred has been making these for decades without complaint, and Graham Russel was happy to recommend it. I daresay that Fred does not use chinese steel in his......
Now you say you have a Quaife LSD, which from memory is a "CLUTCH TYPE" LSD, another manufacturer of this type is Salisbury. There are also "CAM AND PAWL TYPE" LSDs as manufactured by Jack Knight, or a "VISCOUS COUPLING TYPE" LSD as used by my Subaru Forester from the factory. ALL of these work on the principal that when there is a large difference in speed between the wheels then some means is provided to limit the difference in rotational speed or to positively lock it. The advantage here is that if there is a low speed difference side to side, then it will not "lock up" so low speed steering is not so painful. The problem with these is that tey are just way out of my price range at the moment, and hell i just need to get the damn thing going.
And the easy fix to 124 diff problems apart from not dropping the clutch was to stick a 132 diff in them. Yes i have also heard of Cone Type LSD in 124 and 131 diffs.
cheers
michael
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