Atf auto fluid in a 914 gearbox?

[neilbardsley]

I used to run atf auto gearbox fluid in my defender manual gearbox. Changed better from cold and worked well. What do you think about using it in our older 901/914 gearboxes?

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[Cortina]

Don't ask me why exactly ... but I think it's a terrible idea ! (shudder at the thought of it in a defender manual too .................)

[neilbardsley]

Recommended and used by lots of defender owners.

I chicken out and put 75/90 synthetic in

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[Nine One One]

I would have thought you would have been better off with a good MINERAL EP90 as opposed to synthetic, which is not ideal for old style Porsche-type synchros, and apparently does not give enough friction for the synchros. Porsche engineers in the 1960/70’s specifically factored in the gear oil to help slow down the synchro's during engagement. Synthetic oils do not help the pieces slow down and cause premature wear. Synthetic might not make the baulk-ring synchros of the 901/915 boxes work well.

If you speak with Mike Bainbridge he will give you an idea what to use.

[KS]

I would have thought you would have been better off with a good MINERAL EP90 as opposed to synthetic, which is not ideal for old style Porsche-type synchros, and apparently does not give enough friction for the synchros. Porsche engineers in the 1960/70’s specifically factored in the gear oil to help slow down the synchro's during engagement. Synthetic oils do not help the pieces slow down and cause premature wear. Synthetic might not make the baulk-ring synchros of the 901/915 boxes work well.

If you speak with Mike Bainbridge he will give you an idea what to use.

On the back of the label listing the ratios in my 914's gearbox which he rebuilt for me, Mike wrote "fill with oil ASAP: EP80 or 90" – so there's your answer.

[andytat]

Quite a few older gearboxes use ATF. Apparently it's something to do with the compatibility
of the oil with the material of the synchro hubs. Ford Capri, Cortina and Escort gearboxes
all used it from the factory and I have heard about using ATF in Landrover gearboxes.
I don't think it would work well in early Porsche gearboxes due to the design of the sychros.

Andy