Molyslip OK with LSD?

[James]

I've used Molyslip in C900 gearboxes previously and to great effect - it seems to counter some of the natural notchiness and make everything that bit smoother.

My 'new' 900 is very notchy indeed, perhaps because the 'box only has about 10k on it from new (it's not a rebuild). I'd be inclined to give it the Molyslip treatment but it also has a Quaife LSD. Would the two work together, or would I break something?

[SaabCrazee]

Isn't the final drive box separated from the trans, requiring different lubrication for each? With an LSD, the oil must be treated with an additive to protect the clutches and to keep your final drive gears from chattering around tight corners. If the oil galleries of the two are indeed separate, you can run any rated lube you want in the final drive.

Where the heck did yo find a NEW trans???


Cheers,

Jim

[James]

It wasn't me, it was the chap who 'built' the car a couple of years ago. He found a trans on eBay from a car which had done 2,900 miles and then been rolled. It then sat in storage for about 10 years before being broken for parts. Someone else's loss, my gain!

See what you're saying about oil galleries but not sure if it applies in this case. Perhaps Abbott (who supplied the LSD) will help, I'll shoot them an email.

[edit: the Quaife LSD uses helical gears, apparently, not clutches as other LSDs. So less concern, perhaps, of putting the wrong stuff in but I still want to make sure. Anything that makes changing gear smoother and doesn't break the 'box will make me happy ]

[phoenix]

If you can get it over there, I'd recommend Millers TRX75w90

[Emmett Jenner]

No clutches in the quaife, oil is same for whole gearbox, no separate chambers.  Gearboxes will feel more notchy with thinner oil.  Can even crunch a little sometimes.  The most fragile part of the box is the brass syncro rings.  There are also some small oil tubes which could get clogged if the oil used is too thick.  If mollyslip does not block tubes or damage syncros then can't see any reason why not.  Having said that, it is not recommended in the manual.  The recommended oil is EP 75 API-GL 4 or API-GL 5 gearbox oil.  That Millers oil is probably alright.  The oil which is in there is probably 10w40 mineral oil.  Nice and soft but not long lasting. 


I've used this before:



It went into a gearbox I rebuilt for a customer so I don't know how good it was long-term.  Seemed alright after the rebuild on the test drive.

I'm glad I know more than some folks on here.  The first couple of answers to these questions were so far wrong I felt I had no choice but to add a reply in this case!

[sgould]

Reducing friction in a gearbox is not always a good idea.  The synchronising cones rely on friction to work properly.

If an additive can reduce the level of expected friction by a lot, the gear changes may need to be slower to allow the synchro more time to work.

If an additive doesn't change the friction level, it could be a rubbish additive.

[James]

Hmm.  Some interesting points.

I got a reply from Quaife saying there's no issue from their side.  I'm now waiting for the previous-but-one owner of the car to get back to me on what's in the 'box at the mo.