LT77S Transmission problems

[annearj]

hi guys, great forum, have used it as a bit of a knowledge source, but only just joined as a member. Anyways, my old mans defender's transmission has been playing silly buggers. He says its been getting tough to get into gear while driving, it used to be 4th and 5th, but when i saw him over the weekend, he mentioned 2nd has to be double clutched now. It was only rebuilt a couple of years ago, and at that time MTF94 was used, but we're not 100% sure of what was used when the box was last serviced about 6mths ago. Drained a bit out of the box, and there is like a metal sludge in the sump plug - got us a little worried. Any thoughts on what could have been grounded into a paste? We were thinking bearings, or selector forks, but they're generally steel arent they? This metal sludge feels and looks like a soft metal, maybe alloy.

details of his truck, 93 defender, 200tdi, lt77s 5 speed

cheers,

ja

[Fraz]

if its only when your changing into gears, then synchros are the likely bet

I don't think they work as well in paste form ;)

[annearj]

thanks fraz
anyone in perth know of any good transmission builders?

[kelvo]

You should have AFT Dexron II or III in a LT77s not MTF94 (This is for the R380 box), try putting the correct oil in and see it it helps the operation on the box. If it is better replace this with fresh AFT to flush out as much sludge as you can and see how it goes. Dont forget to also clean out the oil 'filter' on the box as well.

[rick130]

You should have AFT Dexron II or III in a LT77s not MTF94 (This is for the R380 box), try putting the correct oil in and see it it helps the operation on the box. If it is better replace this with fresh AFT to flush out as much sludge as you can and see how it goes. Dont forget to also clean out the oil 'filter' on the box as well.

MTF 94 should work better than an ATF as far as synchro engagement goes, and definitely gives better gear and bearing protection.

I'm not a fan of ATF's in manual boxes, there was a reason Land Rover dropped ATF as the preferred fill in the R380 ;)

[annearj]

thanks for the comments guys
ah, the atf or mtf94 debate - seems to be quite a divide among landy owners.
what do u guys think of the slightly thinner gear oils, like 75/85 syntrans?

[rick130]

Syntrans 75W-85 is actually heavier than MTF94.
Redline MTL is closer in kinematic viscosity to MTF94, as is 'Syntrans B', a fluid designed for the T5 gearbox in the XR6 Falcon. http://www.tds.castrol.com.au/pdf%5C5707_SyntransB_117956_200703.pdf
It looks like a good substitute for an ATF.
Plenty of people on here use Syntrans 75W-85 in the LT77 and report improved gear shift performance and less noise than when using ATF.

Have a look in "the Good Oil" section, pretty sure there's lists of 'manual transmission fluids' and their kinematic (actual or measured) viscosities.

Bear in mind viscosity is only one aspect of a fluids possible 'shiftability', the additive package and what friction modifiers it contains often has a greater bearing on shift performance.
Also remember that these gearboxes can be idiosyncratic in behaviour, what one gearbox likes another doesn't shift as 'nicely'.

FWIW I found regular Syntrans 75W-85 offered better shift performance than MTL or MTF94 in my R380, although I've even gone further away and am currently using Motul Gear 300 75W-90 which I find even better again, and due to the high viscosity index is actually thinner than Syntrans at temps below something like 15 or 20*C.

[NCF 110]

I changed my gearbox oil (ATF DEX III ) on Sunday , I undid the 32mm bolt with the magnet , and refilled , I forgot to drain the fifth gear bolt . Can I undo the fifth gear bolt with out losing all the all lthe oil inside the LT77 ?

Stew