Manual Gearbox Questions

[David Killough]

I'm new to the diesel Cruisers, and recently obtained a 95 VX Cruiser with the 24v 1HD-FT turbo diesel. As most UK spec cruisers of that year are, it too is a manual. As I've learned, most Cruisers around the world are automatics, but Toyota apparently took a lorry gear box and put it into the UK spec Cruisers to help them sell. Not sure if that is fact or fiction, but maybe it will explain my problem.

I have a lot of trouble shifting into 1st and 2nd gear from the neutral position. Also, if I'm downshifting from 3rd gear into 2nd, it's quite a pain too. Sometimes I'm able to get in by double/triple clutching.

No manual gearbox in other vehicles I've driven did this unless there was some sort of problem, but I've heard that this may be normal.

Any ideas???

David

 

[Jon Wildsmith]

They can be a bit prone to this by all accounts but yours sounds quite bad. The oil used in them can make a big difference but in your case there's probably more to it than that. I'm sure the experts will be along soon, I've only just got into a manual 80 myself having had a couple of auto 80's in the past. FWIW mine goes in and out of any gear fine so when they're working right they're easy to get on with and yours is not normal but also not that unusual ...

 

[Cptsideways]

Stick some thinner oil in it, that usually helps. They are a clunky box even when new! Try it on ATF for a bit see if that cures it.

 

[David Killough]

Ok, so you lot are recommending a thinner weight oil? I'm not sure about putting ATF in it. Is there a better synthetic oil or something similar? Has anyone had this similar problem and fixed it by changing the oil weight or type?

 

[Jon Wildsmith]

I'll be changing whatever is in mine for this soon on the basis I've read in a few places on the net of it being a good choice for these box's, time will tell ...

 

[Brett]

I've used the Syntrax previously with good results, mine is sometimes a little difficult to get into second from first when cold but is fine when warm

Another possible good oil which I may try next time is MTF94 made by Texaco. It's a 75w 90 full synthetic, Manual transmission oil, which is used by Land Rover in their R380 gearboxes which are also a bit nasty with the wrong oil in. MTF94 completely transformed my R380.

 

[David Killough]

There we go. First hand experience. Thanks Brett! I think I'll give the MTF94 a go and report on what I find.

My gearbox shifts fine from 1st to 2nd or even from 2nd to first, but getting it from 3rd to either 1st or 2nd or from neutral to 1st or 2nd is a pain.

Any idea on the lifespan of manual gearbox oil? I would think that fully synthetic gearbox oil like it's motor oil counterpart would have a longer lifespan than conventional gearbox oil.

Thoughts?

David

 

[Brett]

It's pretty long off the top of my head (I think it might be 24,000 intervals)

 

[Towpack]

I've used the Syntrax previously with good results, mine is sometimes a little difficult to get into second from first when cold but is fine when warm

Another possible good oil which I may try next time is MTF94 made by Texaco. It's a 75w 90 full synthetic, Manual transmission oil, which is used by Land Rover in their R380 gearboxes which are also a bit nasty with the wrong oil in. MTF94 completely transformed my R380.

That's exactly how mine is. A little 'sticky' when cold but fine after around 10 mins use.
I also use the Castrol Syntrax and feel the box is better for it. Don't know wether it's a truck sourced gearbox or not. The throw of the lever is quite long and slow but it's not a sports car after all so no big deal really.

Some early (like my old Disco) R380 gearboxes had an oil starvation issue on the 2nd gear, eventually causing crunchy 1st to 2nd shifts but this was fixed with a new gear that had an extra oilway drilled/machined into it.

 

[LandCruiser1978]

i have a similar issue ..

only going from 2nd to 3rd feels abit and i do mean abit crunchy/tight
But once warm is silky smooth
so what i've started doing is avoiding 3rd untill the box is warm

So come on experts how much and what oil

is the stuff jon said the best for the job?
http://www.opieoils.co.uk/p-744-castrol ... ersal.aspx

 

[frank rabbets]

The correct oil is "multipurpose gear oil. API GL4 or GL5. SAE 75w90". On my first oil change everything was OK but on the second oil change I found I could no longer obtain this oil. I tried various types of synthetic gear oil and eventually ordered the correct oil from Toyota which was synthetic. However 2nd and 3rd gears are difficult especially when cold and none of the oils now give the better gearchange that the old type oil gave.

The AM DB5 and DB6 cars which I had in 70's were made in 60's and had a monster ZF 5 speed gearboxes. It was impossible to get into 2nd when cold.

Do not put EP oils in this box it will attack the bronze syncro rings.

Even the slightest amount of clutch drag; which one may not even be aware of will make changes worse.

Frank

 

[LandCruiser1978]

Even the slightest amount of clutch drag; which one may not even be aware of will make changes worse.

Frank

WHAT DO YOU MEAN?
Whats clutch drag

 

[Graham]

When you fully depress the clutch pedal, and the friction plate is not totaly seperated from the flywheel, and the pressure plate.
It is the splines from the center of teh friction plate that transmit the power into the gearbox, and some times, this still rotates slowly.
Hence why it is some time more easy to get a gear, when the truck is still moving forward.
Also you must consider that the syncromesh rings, the sycromesh rings are brass toothed rings, and are used to align the gear teeth when changing up the box.
there brass syncro rings, are some what of a sacrificial offereing so the driven teeth in the geatbox, ie, between the lay shaft and the gear cluster don't simply crash into each other on gear changes.
Having a thick oil in the gearbox, some times provides enough friction to also keep the shafts (input and lay & output) from spinning, thus preventing the syncro rings from meshing the teeth.
On the way down the box, there are "cones" if I remember right.

Take this with a table spoon of salt, as it was a long time ago I used to strip the boxes down, etc.

Tellus 33 hydraulic oil was always a firm favorite, nice an thin, and offered great metal separation.

Gra.

 

[frank rabbets]

Hi Geordie

I think Graham has explained that well. I shall be seeing if I can get a syringe filled with oil and a pipe on into the bell housing and try and get a drop or two onto the input shaft to see if lubrication on the clutch plate splines will improve my change. Please don't try this at home. I'll update the post accordingly.

Frank

 

[David Killough]

The correct oil is "multipurpose gear oil. API GL4 or GL5. SAE 75w90". On my first oil change everything was OK but on the second oil change I found I could no longer obtain this oil. I tried various types of synthetic gear oil and eventually ordered the correct oil from Toyota which was synthetic. However 2nd and 3rd gears are difficult especially when cold and none of the oils now give the better gearchange that the old type oil gave.

The AM DB5 and DB6 cars which I had in 70's were made in 60's and had a monster ZF 5 speed gearboxes. It was impossible to get into 2nd when cold.

Do not put EP oils in this box it will attack the bronze syncro rings.

Even the slightest amount of clutch drag; which one may not even be aware of will make changes worse.

Frank

What are EP oils??? Is MTF94 an EP oil and should I not use it in my gearbox? I'm getting ready to change the rear output shaft oil seal, so I'll be needing to replace the oil when I do that. I don't want to damage the gearbox with the wrong oil, however, I'm not averse to changing oils if it will help it shift better without damaging it.

 

[Graham]

EP = Extended Purpose.


Hi David,

as an experiment, drop all the oil out the gearbox, and save it.
Buy a couple of liters of the Tellus 33 (it's a Shell oil)

Run it for week, and tell me how the gear changes are.

Gra.

 

[AndycruiserguyLomas]

Sorry to have to correct you Gra but the EP designation when referring to the specification of oils stands for "Extreme Pressure".
It was developed years ago when final drives evolved with helical cut gears rather than bevel type for greater strength and quieter operation. Because of it's shearing nature of operation,the addition of sulphur and phosphorus was necessary to provide protection for the hardened surface of the gears.

Hope this helps with this discussion.

Andy

 

[Graham]

Hi Andy,

I can go with that,

Gra.

 

[frank rabbets]

David, on the oil container it will describe in general terms what the oil is for; either gearboxes or back axles.

Frank

 

[David Killough]

Ok, so what I'm gathering is that the manual gearbox in an 80 series is a syncromesh gearbox. It's not recommended to put an "EP - Extreme Pressure" oil in the gearbox as it will shorten the life of the bronze synchro's.

Therefore, the MTF94, which is a non-EP fully synthetic oil should work fine. Here's a description from the opie oils website:

"AMSOIL Synthetic Synchromesh Transmission Fluid (MTF) 5W-30 meets and exceeds the gear, bearing, synchromesh and seal demands found in automobiles and light trucks. AMSOIL Synthetic Synchromesh Transmission Fluid (MTF) is specifically designed for manual transmissions and transaxles with synchromesh systems that require light viscosity, non-extreme pressure fortified oil. It is formulated with advanced additive technology to provide proper friction characteristics for smooth shifting without grinding or bump shifting, while providing the ultimate in gear and bearing protection. MTF provides far better protection in these manual transmissions than petrol or diesel motor oils."

Now, I understand there is marketing involved here, but based on their description, does this sound like a safe, non-transmission eating oil?

David