Car's in workshop right now having a clutch replaced. I've supplied the new clutch, G280 in/out/selector seals + the crank rear main and then completely forgot about the oil for the gearbox!!
Need some ideas please. Something that will obviously allow the synchro rings to work but at the same time will hopefully damp down the layshaft rattle at idle. It's been a long time since this gearbox oil was replaced. I think it was replaced last time with either RedLine gear oil or ATF. Not sure, but obviously things have probably moved on since then. What's the current thinking please? Looking for advice and experience reports to help make a decision.
Cheers
Thanks mate, found some MT-90 locally and got that to put in this weekend. Cheers
I think the Redline website still has recommendations for our cars.
Rob E3
Yeah they do, for US market cars at least (which is understandable). The Red Line website recommends MTL for the G280, but the US market cars only got the later improved v2.0 of the G280. There is commentary I've read elsewhere that there's two versions of the G280 as it went through a minor facelift redesign at midlife somewhere along the line. Early G280's had brass synchro rings which were changed to something else in the later version and were much more susceptible to the gear wheel/layshaft 'chatter' at idle with the clutch engaged. Being an '85, I'm pretty sure my gearbox is one of these early model ones as opposed to the quieter running later model version the US cars got.
Hence MTL or the 80W oil is recommended for the US cars for better cold weather running, while the early cars like mine are better off with the slightly heavier MT-90 (90W oil) to dampen down the inherent layshaft rattle a bit.
Some others suggest a 50:50 mix of the two for a middle 'best of both worlds' kinda thing. Apparently you can safely mix the two together in any ratio you like and this is even suggested/recommended to some degree if you can't get exactly the effect you want with one alone.
Last edited by Legoman; 05-24-2019 at 09:12 PM.
Hey Rob how are you doin'???
I'm wondering why most guys are using a gear oil in the boxes
when it clearly says on realoem and the manual that the
5 speeds require ATF.
Could it be that long term gear oil use has screwed up the synchros and bearings
that increasing viscosity will help things out?
When I bought my Metric Mechanic 5 speed, Jim told me use nothing but ATM.
The shifting forks have dimples that slow down the synchros when shifting.
If you use gear oil the thick viscosity clogs the dimples reducing friction
and the synchros wear prematurely.
It's just a wonderment on my part that when the info from BMW
and BMW tranny re builders are recommending ATF, most of the community is using gear oil.
Hope there's an "Idiotfest" this year- would be good to see you.
Bob V
Possibly because when you do use ATF the gear rattle that results is horrendous and very, very uncivilised. Maybe it wasn't when the gearbox was brand new and not even run in to allow them to sell the cars, but once run-in, there's no way on Earth you'd have bought one of these cars with ATF in the gearbox. The noise sounds like the gearbox is filled with swarf and random left over bolts.
Disclaimer: My car's done 85,000 miles since new and never been rebuilt.
Legoman,
Thanks for the feed back. So you're saying that when ATF was used from the factory
after a while gear rattle reared its ugly head and to quiet it down gear oil does it.
Makes perfect sense. Now I ask myself will I eventually have this problem or
will the tapered shaft bearings that Jim used in the rebuild stand the test of time?
Interesting thread, I'm getting ready to change the oil in my Getrag, so this has been a good and education read.
Car in workshop with G280 out
No leaks, bit of uneven scalloping on the flywheel, so that's getting a tizzy-up, worn clutch fork pivot bearing (to be replaced), fork is fine to reuse, new clutch (old one looks fine actually, but just has had too many heat cycles, is hard and glazed so being replaced), new selector rod knuckle bearing (worn/loose), new MT-90 oil (old stuff was Redline gear oil of some description, not ATF), nothing unusual on mag drain plug, new spigot bearing into back of crankshaft, new input/output/rear crank and selector rod seals (just because) and will be all good to go again.
Last edited by Legoman; 05-28-2019 at 01:01 AM.
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