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Automatic transmission fluid ?

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bluecatmodels Avatar
bluecatmodels Silver Member Dave W
Three Rivers, CA, USA   USA
My mechanic will be working on my overdrive, which has never worked. He asked what fluid I was using and I told him 30 weight non detergent oil. He says that he prefers automatic transmission fluid. He is an experienced European auto mechanic. Does anyone have any experience with this, any thoughts?
Thanks, Dave

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NaDaDawgRacer John Jones
Waxhaw, NC, USA   USA
Not sure what European cars your mechanic works on but he evidently has not worked on a Leacock overdrive unit. It shares the same oil as the the gearbox. You would not want to run autotrans fluid in the gearbox.
John

bluecatmodels Avatar
bluecatmodels Silver Member Dave W
Three Rivers, CA, USA   USA
John,
Thanks for the reply. I feel the same way. I will question him about this and see if he has any justification for it.
Dave

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layaj2 Andy Lay
Bisley, Surrey, UK   GBR
I use the same oil as in the engine, Castrol classic XL 20W-50. It's non unheard of for automatic transmission fluid to be used with a manual gearbox, although I've never come across this personally. All my old cars with manual/overdrive from Jaguar, Triumph etc have used either gearbox or engine oil.

Andy

RAC68 Avatar
RAC68 Raymond Carbone
NJ, Jersey Shore, USA   USA
Hi Dave,

A number of British Marks as well as Volvo have installed, Laycock Overdrives with their manual transmissions in numbers. Where Jaguar and Triumph recommended 90W Gear Oil, MG and Austin Healey favored 30W Engine Oil, and Volvo, the main non-British user, chose to install Automatic Transmission Fluid (ATF). Keep in mind that although the fluids chosen all seem to function within the OD, fluid selection may be closely keyed to the materials used within the transmission or even connected to OD designed differences within the specific units supplied by that group.

Your mechanic may have sufficient knowledge and experience of Volvos and feels the ATF has qualities that could assist in correcting the operation of your unit. Since many today do not follow the use of a non-detergent oil that would allow any internal debris to fall out of oil-suspension but favor a multi-grade detergent oil that is meant to keep debris in suspension until cleared with a filter, today's high detergent ATF may have qualities that may be out of the question.

However, I would question your mechanic on his experience with the Healey, its transmission/OD, and his basis for suggesting ATF in your Healey.

Hear is a document that will also give you some indication of viscosity and internal pressures and operational conditions produced by a number of fluids (http://www.mgtoronto.com/pdf/Tech/Overdrive_oil.pdf)

Please keep us informed of his justification,
Ray(64BJ8P1)



Edited 1 time(s). Last edit at 2018-04-12 07:00 PM by RAC68.

Phil.Daniels Avatar
Phil.Daniels Phil Daniels
onalaska, WA, USA   USA
You really need to stay with your original problem, non functioning OD. To go straight from a non functional problem to a radical solution such as putting in ATF is so not right. The first thing any knowledgeable mechanic would do is to check the electronics and see if the solenoid moves the selector. If not, check the switches in the system and work down to the solenoid it self. That checked and operational, then they need to check the OD pressure. It has to be in the 450 to 500 pound area. Keeping in mind that the OD is a slip system and you will not have proper operation if it is slipping, you need to be sure to use a non detergent oil like the 30 wt.

It is suggested you find a mechanic that is familiar with the Healey.
To be a European car mechanic does not mean they have the working knowledge around a 50+ year old Healey.

bluecatmodels Avatar
bluecatmodels Silver Member Dave W
Three Rivers, CA, USA   USA
Thank you all for the advise. The problem is definitely inside the OD. It will not build up pressure, probably due to worn O rings on the pistons. I will stick with the 30 weight oil. The article that Ray provided is interesting. I will forward it to my mechanic. He expects to pull the trans and OD next week. Hopefully it will be an easy fix. I'm also putting on new 72 spoke wheels and going through the brakes and front end. The weather is great here and I am suffering through withdrawals for not being able to drive the Healey. For the past few years the lack of having an OD has really held me back. I look forward to a new experience.
Thanks again,
Dave

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RAC68 Avatar
RAC68 Raymond Carbone
NJ, Jersey Shore, USA   USA
Hi Dave,

Yes, 30W motor oil is what was originally recommended by Healey. However, today's motor oils are not like that of the 1960s when Esso 10W30 was the common oil used in our engines. Today, I use Mobile 1 15W50 synthetic in my engine and others feel oils like Castrol 20W50 is preferred. For my transmission/OD, I changed from 30W non-detergent motor oil to Red Line synthetic MTL. Red Line was designed with a viscosity similar to 30W motor oil and 80W gear oil and, I believe, all the correct additives needed for my transmission and OD. Although the Red Like has performed flawlessly in both transmission and OD, it does seem to find drip out and has caused me place cardboard under the car to absorb the drips.

I mention this because many have used other oil types and it has not been uncommon to learn that others prefer to use the same 20W50 detergent oil used in their engine with no indicated ill effects. Although I would not recommend ATF, keep in mind that automatic transmissions use clutches and depend on hydraulics not to different from our ODs. Additionally, Automatic Transmissions were being introduced in the early 1950s and starting to become more common in the 1960s.with AT Fluid still in its early design stages at the time Healey established their lubrication recommendations. As with all oils and lubricants, everything has changed and depending on past qualifications is no longer feasible or safe for even today's 30W non-detergent motor was not around when my car was new.

Please don't misunderstand, I am not suggesting you switch to ATF. Question your Mechanic and evaluate his logic and basis for his ATF recommendation before discarding it. He may know something we don't.

All the best,
Ray(64BJ8P1)



Edited 3 time(s). Last edit at 2018-04-14 02:29 PM by RAC68.

PAN Avatar
PAN Alwyn Keepence
Ipswich, Queensland, Australia   AUS
G'day Dave,
If your overdrive does not have enough hydraulic pressure the problem could be the accumulator.
Be sure to check all of the electric systems.
In our warm south-east Queensland climate, I use 40 weight non detergent oil.
Cheers,
Alwyn

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