is far as im told, worn LSD act like open diffs

 

how do open diffs act??

 

 

That is fine. The viscous needs the fluid to heat to lock up. If you didn't spin it enough or there was not enough heat to lock the fluid it would just sit there.

And you can't rebuild the viscous one. It is a sealed unit.

Now if you were spinning one wheel and the other was going the opposite direction, that would indicate a blown out or open differential.

 

ok, so my diff is supposed to be fine? was just wondering, 'cause i thought there was not much traction that day at the dragstrip! once when i hit 2nd the wheels started spinning pass the 1/8-mile (the crowd did enjoy, but my time slip was ****!)! is the FC lsd actually just not that good...??

 

Clutch diffs should turn both the same way, opens the other will spin the opposite way as the one you are spinning.

A person turning a wheel can not make a viscous diff "lock up" unless they're the incredible hulk and the flash in one, and are able to heat it up sufficiently... and no you can't do that.

vLSD's suck a fat dick anyway.

 

Your diff is probably fine... the Viscous LSD just takes a lot of slippage to lock up, and is a poor poor choice for a drag car. They are more designed for poor weather conditions and cornering and mountain roads.

 

You may have a dragging brake as well which would cause one side to be immobile while spinning the other.

 

is an s4 open diff to s4 lsd a direct job? any extra stuff or mods needed? and the s4 diff is a clutch type right?

 

what are the pros and cons of each? is one definatly better, or does it depend on what you're usin your car for?

 

I feel it really depends on what you are using the car for and what climates you are using the car in.

For example, the Viscous is by far the quietest, and is the best application for the average driver who does a littel bit of everything. It is weakest at drag type racing, but it lasts forever and you really can't ever burn one up. It locks up slowest of all.

The Clutch type, is probably the best choice for the guy that wants to go dragging or needs to prove his manhood at the stop light. It tends to be noisy, and requires special lubricants, but locks up the fastest of all.

The Torsen type is by far the best choice if you are driving in poor weather or poor traction conditions. It transfers power to the wheel with the most traction instead of locking up. But it does not handle big power real well.

Locked differentials are almost useless for anything but straight line drags, as cornering in high traction areas wears out tires and the differential fast, and cornering in low traction areas tends to cause the whole rear end to chuck and break loose.

Open differentials (as found on most S5 FCs) tend to be cheap, but transfer the power to the wheel with the least amount of traction. In worst case, they loose traction on both sides causing a burn out that some people mistake for having a LSD, but in reality, they simply have poor traction.

 

sweet, that was very informative. but is the s4 open diff to s4 lsd a direct job?

 

If you swap the differential assembly, yes, it is a direct and easy swap.

Differential assembly= differntial, front housing, rear pumpkin, pinion, gear, and assorted washers and mounts

if you are just swapping the differential, then you will need to have the pinion set to the right tension to the gear on the differential.

 

Gear installs are pretty cheap though. Just take it to a local offroad shop. They'll do it for 150 bucks most of the time. 300 if they are steep. Then you just bolt the pumpkin into your car.

 

depending on gear height you may also need to re-space the pinion shaft.

You always need to check so that the pinion gear matches up to the correct spot on the differntial gear. The FSM has a great section for showing you how, and how to figure out what washer/spacer you need.

 

To do it properly, you'll need a dial indicator and pinion depth checker. dial indicators are cheap, but the pinion depth checker (for a decent one) is like 300 bucks.

The "re-spacing" you are referring to is called backlash. You need to adjust it so that your gear pattern on the coast and drive sides of the ring gear is somewhere in the middle to the edge. You don't want it to far on the edge, or too far to the center. Requires buying a full shim kit for our diff's and adding some on either side, and the pinion, until its all set. Its a bitch the first time you do it. If you don't plan on doing it ever again, I'd just take it to a shop.