Friction Modifier

[rusty88]

Good Evening all.
I'm just in the process of creating an order for gearbox and diff oil.

Should I also buy some friction modifier for the diff? Is 1 bottle likely to be enough?

Thanks Alex

[mfp4073]

From what I remember you should only add a small amount of friction modifier at a time.
If you put too much in the Diff will not lock up, too little and it will be noisy.
Also the diff oil needs to be warmed up a bit to work properly.
So the answer to your question, 1 bottle will be enough.
I gave up with mine and had a truetrac fitted.

Regards John

[build294]

I did the same i got fed up of keeping it quiet so got a trutrac fitted, maint free is a good way to go. As said small amount at a time. Think i used the redline brand

[rusty88]

Thanks for the replies guys.
Unfortunately a truetrac is just out of my budget at this moment in time so I'll have to settle with having mine serviced for now.

So, as I won't be doing it myself, is application of friction modifier a task that a respectable garage would be familier with?

[mfp4073]

rusty88 said:

Thanks for the replies guys.
Unfortunately a truetrac is just out of my budget at this moment in time so I'll have to settle with having mine serviced for now.

So, as I won't be doing it myself, is application of friction modifier a task that a respectable garage would be familier with?

Yes it's easy to do, but it can take a few attempts to get it right.
Take the car for a drive to warm up the Diff oil.
Clean the dirt off the drain and filler plugs.
Drain out the old gear oil.
Refill with the correct grade of oil, but don't over fill.
Add a small amount friction modifier.(just a few cc's)
Replace filler plug.
Then take the car for a drive to warm things up again.
When it's warm try some slow tight right and left turns, if you feel the car judder it will need more modifier added.
If you are happy the Diff has enough modifier added then top up the Diff with gear oil.

I think that covers the job?

Regards John

[notransistors]

Always be certain to remove the filler plug before removing the drain plug. What do you think would happen if you drained the gearbox and then could not get the filler plug out?

[neiljohnson]

I've found that if you use the royal purple in the diff your not likely to need modifier as it already has some in it

[bigwheel]

neiljohnson said:

I've found that if you use the royal purple in the diff your not likely to need modifier as it already has some in it

[rusty88]

Great stuff that's what I've ordered
Going in tomorrow morning.

[Phillphill]

The juddering if not enough friction modifier is added, is it doing damage to the diff. Yes i understand wear and tear etc. But is it actually doing real damage?
My diff is st wether that is characteristic of these diffs, it locks but when it feels like it, I dont mind juddering, I had a very tight diff on my old car

[rusty88]

My diff clunks like hell if I'm too quick on/off the gas and my gear changes are getting to be quite stiff and also causing clunks.
I'm hoping these oil changes sorts it out.
No juddering though.

[mfp4073]

Once you have changed the oil in the Diff and gearbox, check the prop shaft and half shafts for excess play.
Even when all is well, don't expect these cars to be clunk free.... they just clunk when they feel like it!

John

[rusty88]

Thanks I'll get them to check it tomorrow. I'm having diff seals changed anyway so I'm guessing they will be taking prop/half shafts out anyway?
I've had it pointed out to me before that there is quite a lot of play on prop shaft/diff.

[notransistors]

Many of us here have found Royal Purple to be junk. In the GTO we use Torco plus their friction modifier. Works best, assuming that you have the same differential. And BTW, the manual gearbox will only work with Dextron III. Not IV or V or VI, so keep that in mind when you change tranny fluid.

[THUNDER STORM]

notransistors said:

Many of us here have found Royal Purple to be junk. In the GTO we use Torco plus their friction modifier. Works best, assuming that you have the same differential. And BTW, the manual gearbox will only work with Dextron III. Not IV or V or VI, so keep that in mind when you change tranny fluid.

When you say same differential, does that mean standard as fitted to Monaro VXR?

Ade

[rusty88]

Well that's diff and gearbox oil + seals changed.
There is still clunking when changing gear and when depressing clutch pedal. Sounds more like it's coming from transmission area.
Gear changes feel stiffer and more "metallic" sounding than they were a few months back.
I've also had ls7 clutch installed, slave cylinder and spigot bearing replaced a short while ago.
My mechanic had a look at prop shaft while it was out this time and couldn't find anything wrong with it.

Any thoughts?

[notransistors]

THUNDER STORM said:

When you say same differential, does that mean standard as fitted to Monaro VXR?

Ade

Yes. The Monaro XVR is the GTO, but RHD rather than LHD and Vauxhall rather than Pontiac.

[Janosh]

rusty88 said:

Well that's diff and gearbox oil + seals changed.
There is still clunking when changing gear and when depressing clutch pedal. Sounds more like it's coming from transmission area.
Gear changes feel stiffer and more "metallic" sounding than they were a few months back.
I've also had ls7 clutch installed, slave cylinder and spigot bearing replaced a short while ago.
My mechanic had a look at prop shaft while it was out this time and couldn't find anything wrong with it.

Any thoughts?

Have you checked the drive shafts?

[rusty88]

Don't think they've been looked at yet no.