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[Albatross]

The only sure way of telling is to remove the back plate off of the diff. If you cant see the pinion gears then its a slipper

Is a "slipper" an LSD or a non-LSD? What do the pinions look like?

It's the sun gears and planetary gears that drive the two output shafts. Normally visible in a frame that is attached to the large crown wheel, on an LSD there is just a metal cylinder here with the gubbins in.

Turning the output shafts isn't a reliable method on this type of diff. It works nicely on viscous LSDs as fitted to the RWD Fords.

A "slipper" as another term for a LSD.

Next questions:

Are all the Ratio's the same on the LSD? Do I need to be looking for a specific version to suit my 3.2 auto?

Are they difficult to swap over from the original? What's involved?

[Kevin Wood]

Next questions:

Are all the Ratio's the same on the LSD? Do I need to be looking for a specific version to suit my 3.2 auto?

Are they difficult to swap over from the original? What's involved?

IIRC the LSD is only available in one ratio which is slightly shorter than the 3.2's normal ratio, but I may be wrong.

Changing the ratio is possible but a reasonably specialised job because the mesh of the pinion and crownwheel would need to be set up. Might require some special tools, new crush washers, etc. along with plenty of patience IME.

Kevin

[Albatross]

Would the fact that the ratios are slightly shorter matter?

What effect would that have?

Did plod cars ever have v6 3.2 with LSD?

[Kevin Wood]

Would the fact that the ratios are slightly shorter matter?

What effect would that have?

Did plod cars ever have v6 3.2 with LSD?

You'd have slightly higher RPM at a given road speed. Maybe slightly more sprightly acceleration in the gears, maybe slightly more thirsty on a motorway run. Not a great deal in it though. It'd be woprth finding out the ratios and then you can calculate what the difference will be.

Kevin

[Albatross]

Any ideas on where I might find out about the ratios on each?

[markey mark]

Any ideas on where I might find out about the ratios on each?

haynes manual  

[Albatross]

Taken from an ABS post:

"...the Haynes story book it says that post 1998 the diff ratios for Omegas are as follows.

2.0 Manual 3.9:1
3.0 Manual 3.7:1 (I think that applies to the auto as well)
2.5 Manual 3.9:1
2.5 auto 4.22:1

Pre 1999...

2.5 Manual 3.7:1
2.5 Auto 3.9:1 "

Where does that leave me with regard to a 3.2? I don't think they did a Haynes manual for the 3.2 & 2.6.

I don't have a Haynes manual either, so I can't find out whether it even mentions the LSD ratios.

Is there anyone out there who has got one and who would be willing to check for me?

 :-/

[Albatross]

Another interesting post...

"no 'normal' Omegas came with LSD

All police-spec Omegas had LSD ( fitted by MSD as part of the conversion package )

All ABS units have a high-pressure pump - and work in the following way :-
Upon detecting a spinning wheel, the solenoids momentarily engage (block the flow) to prevent brake pressure reaching the calipers. AT THE SAME TIME, the high-pressure pump starts running to recirculate some of the fluid that has already reached the calipers back to the master cylinder. ( that's why ABS cars have a different master cylinder )

On Omega, the traction control uses the ABS sensors to detect if there's a loss of traction ( or more likely to detect if you've just been over a drain cover )

All V6 Omegas had traction control, No in-line 4's did.

All the above is true UP TO AND INCLUDING OMEGA FACELIFT.

from facelift onwards, a more advanced ABS is fitted which can actually apply the brakes on its own - this is linked to the ASC/ESC (stability control system).

As for LSD in an Omega, you have four options:-

1. fit the internals from a Carlton/Senator B LSD into an Omega casing. This all works ok and everything fits. The hardest part is the working of a month's overtime to be able to afford the crownwheel carrier bearings. A good tip here is to buy the oil seals from a bearing supplier, as the 'genuine' front oil seal has changed, and GM will try to sell you a prophsaft flange as well.

You also have the advantage of being able to keep your old crownwheel and pinion ( no diff-ratio problems to worry about ).

2. fit the internals from a Senator A LSD into an omega casing. This is broadly as above, but you will have to get a chamfer machined into the inner end of the through-hole in the diff planet wheel, as Senator A had the inner Cv joints secured by a circlip rather than the later car's spring-ring.

3. modify a Carlton rear subframe for use in the Omega. This entails cutting the subframe rear mounting lugs off an Omega subframe and welding them onto a Carlton one. It's not at all difficult, you can then use the Carlton LSD without having to open it, together with your modified subframe. Incidentally, this also works well on Carltons and means that you can use the Omega wide-spaced rear subframe rear mounts instead of the single Carlton central mounting block.

4. buy another LSD from an after-market manufacturer, such as Quaife.

I have done 1,2, and 3 - all successfully. ( but not 4. 'cos i'm a tight-wad )

In theory, LSD and the traction control should 'fight' a bit, but the traction control on the Omega really isn't intelligent enough to work out that it's got LSD. This might be a different story on a facelift car."

Still haven't managed to get to the bottom of the different ratios yet though. :-/

[Peter H]

This is a very interesting thread.

My $0.02

It may interest you to know that BMW no longer list a slipper as a option on their cars, M's get a active diff and the normal road cars rely on the traction control.  How very boring, mileas away from the good old days and not really 'the ultimate driving machine' is it?

The Omega rear suspension is very very similar to that of the BMW E34 (1989-1997 5 Series) and those cars suffer from serious void bush wear if a slipper is fitted, also BMW fitted LSD to large engine manual cars but is was an option of all autos.

The reason not to have a slipper on an auto is that if the wheels begin to spin, and the car steps out of line the drivers response in most cases is to close the throttle (some of us go wahey and plant it humming the theme from Dukes of Hazzard).  
The auto box uses its very simple logic to equate wheel speed to engine speed and throttle position and change up to top.  The car then GRIPS with the wheels being driven at the tickover creep speed.
If you have opposite lock on and a slipper probably puts you straight into the nearest wall.  With out a slipper the one wheel would spin only and the angle of drift would be less, but less under control.

On a manual this is not a problem as the quickly closed throttle would have a braking effect on the rear wheels which with an LSD will tend to pull the back of the car back into line.

On a manual the LSD helps the driver reatin control by 'locking' the axle and allowing a skilled driver to control the car.
On an auto the driver has not got full contol of which gear he is in, and as the gearbox changes up to top the torque is reduced thereby causing the sudden grip.

My XJ-S has a 3 speed auto, a Locking action Powrlok LSD and a creep speed of about 30mph.  Caution is advised, if it slides the best thing to do is to hold the throttle position and steer through it.  I have never been brave enough to try this!

An LSD is a nice touch for very fast road driving or towing or if you often drive in treacherous icy conditions.  For most it is not necessary.

In my humble opinion.

[TheBoy]

Another interesting post...

"no 'normal' Omegas came with LSD

All police-spec Omegas had LSD ( fitted by MSD as part of the conversion package )

All ABS units have a high-pressure pump - and work in the following way :-
Upon detecting a spinning wheel, the solenoids momentarily engage (block the flow) to prevent brake pressure reaching the calipers. AT THE SAME TIME, the high-pressure pump starts running to recirculate some of the fluid that has already reached the calipers back to the master cylinder. ( that's why ABS cars have a different master cylinder )

On Omega, the traction control uses the ABS sensors to detect if there's a loss of traction ( or more likely to detect if you've just been over a drain cover )

All V6 Omegas had traction control, No in-line 4's did.

All the above is true UP TO AND INCLUDING OMEGA FACELIFT.

from facelift onwards, a more advanced ABS is fitted which can actually apply the brakes on its own - this is linked to the ASC/ESC (stability control system).

As for LSD in an Omega, you have four options:-

1. fit the internals from a Carlton/Senator B LSD into an Omega casing. This all works ok and everything fits. The hardest part is the working of a month's overtime to be able to afford the crownwheel carrier bearings. A good tip here is to buy the oil seals from a bearing supplier, as the 'genuine' front oil seal has changed, and GM will try to sell you a prophsaft flange as well.

You also have the advantage of being able to keep your old crownwheel and pinion ( no diff-ratio problems to worry about ).

2. fit the internals from a Senator A LSD into an omega casing. This is broadly as above, but you will have to get a chamfer machined into the inner end of the through-hole in the diff planet wheel, as Senator A had the inner Cv joints secured by a circlip rather than the later car's spring-ring.

3. modify a Carlton rear subframe for use in the Omega. This entails cutting the subframe rear mounting lugs off an Omega subframe and welding them onto a Carlton one. It's not at all difficult, you can then use the Carlton LSD without having to open it, together with your modified subframe. Incidentally, this also works well on Carltons and means that you can use the Omega wide-spaced rear subframe rear mounts instead of the single Carlton central mounting block.

4. buy another LSD from an after-market manufacturer, such as Quaife.

I have done 1,2, and 3 - all successfully. ( but not 4. 'cos i'm a tight-wad )

In theory, LSD and the traction control should 'fight' a bit, but the traction control on the Omega really isn't intelligent enough to work out that it's got LSD. This might be a different story on a facelift car."

Still haven't managed to get to the bottom of the different ratios yet though. :-/

The ABS braking info is 'dangle berries'.

[sassanach]

lsd ratio for 3 litre auto is 3.9 to 1, manual is 3.7 to 1

[Albatross]

lsd ratio for 3 litre auto is 3.9 to 1, manual is 3.7 to 1

Thanksfor that,but I didn't think they made an LSD auto.

Having read the post ^^ above about the worries of losing hte back end, and other threads I have read on ABS about increased tyre wear and occasional judder I'm beginning to think it isn't such a good idea to fit an LSD to my car.

If I did (and it's a big IF) I think I'd go the whole hog and investigate an auto to manual conversion, but I don't how how possible that is in a 3.2.

[sassanach]

they did make a lsd auto,ive got one!!!

[Mr Skrunts]

Some more bits of info in this thread.

http://www.omegaowners.com/forum/YaBB.pl?num=1176773486/20

[Kevin Wood]

lsd ratio for 3 litre auto is 3.9 to 1, manual is 3.7 to 1

Thanksfor that,but I didn't think they made an LSD auto.

Having read the post ^^ above about the worries of losing hte back end, and other threads I have read on ABS about increased tyre wear and occasional judder I'm beginning to think it isn't such a good idea to fit an LSD to my car.

If I did (and it's a big IF) I think I'd go the whole hog and investigate an auto to manual conversion, but I don't how how possible that is in a 3.2.

I think the comments about auto boxes are probably valid for a pure mechanical/hydraulic autobox but the Omega's electronically controlled box is likely to be more sophisticated. It can tell by the sudden acceleration of the output shaft without additional torque input that something odd's going on, for a start. It may even receive information from the ABS/TC ecu saying the TC has activated.

LSDs do make a car more prone to stepping out at the rear if the limits of traction are exceeded but they also raise those limits considerably, and, if a slide develops, it'll be more controllable in an LSD equipped car than one with an open diff, IMHO. The biggest advantage, again IMHO, is that the tendency to spin the inside wheel when pulling out of a junction is gone. It won't make the car a monster IMHO, then again, I've never driven an Omega with one, and I'm used to Ford viscous LSDs which have very gentle characteristics.

I suspect the main reason that they are less popular these days is that they cost significant money to incorporate, whereas a few extra lines of code in the ABS/TC system firmware comes for free.

Kevin