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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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raschwar Avatar
raschwar Richard Schwartz
Washington Crossing, PA, USA   USA
I agree with Phil, troubleshoot the problem. Does it engage at all or does engage and the drop out? It could be as simple as the ball check on the actuating valve needing to be reseated. this happened to me upon receipt of a "rebuilt" gearbox/OD. The procedure to reseat and calibrate is done from outside of the box. If this valve arrangement leaks enough pressure cannot be maintained to hold the OD in position.

Good Luck
Rick



Edited 1 time(s). Last edit at 2018-04-27 08:17 AM by raschwar.

LDN Ole S
Ben Lomond, CA, USA   USA
I use Redline MTL 90. I completely rebuilt the transmission and overdrive. Have put about 5k miles on it. Shifts smooth and the overdrive engages quickly with no slippage.

bluecatmodels Avatar
bluecatmodels Silver Member Dave W
Three Rivers, CA, USA   USA
Here's the latest. I picked up my Healey from my mechanic, but he won't be able to work on the OD until this fall. He replaced the OD switch and the solenoid clicks on just fine, but that is all. He drained all the fluid from the trans and the OD and replaced it with ATF fluid. He explained that it was similar to 20/50 oil and he had been using automatic trans fluid for years without any problems. He also installed new spoke rims. It is great to drive on wheels that are actually ROUND.

I've put a few hundred miles on it over the last few weeks and it shifts smoothly, but still no overdrive. He said the clutch is also slipping, so he will be replacing the clutch plate as well. I hadn't noticed the clutch problem but my son had also mentioned it. I am not an aggressive driver but now that this has been pointed out I noticed that it takes a long moment for the transmission to catch up with the engine. I look forward to the day when I can cruise at 2500 RPM instead of 4000.

Thanks for all your comments. I will update you when the time comes.

Dave

San Jose, CA, USA   USA
In reply to # 200549 by NaDaDawgRacer 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

FWIW, ATF is called-for in the 5-speed Tremec manual gearbox in my Mustang GT, so it's not unheard-of (I run Royal Purple Synchromax, on advice given by a Mustang 'expert;' it did improve shifting feel). ATF has to withstand some pretty high temps in an automatic gearbox, and would need the same lubricating properties as would a manual gearbox. BTW, it's 'Laycock,' not 'Leacock.'

Having just overhauled a Laycock deNormanville OD, I can offer the following SWAGs:

- the solenoid moves a lever that turns a shaft with a cam that operates the valve that switches high pressure fluid--ATF or otherwise--into a couple pistons. If the lever is slipping this would cause the OD to not operate even if everything else is in good nick. This can be easily verified as there is a lever on the shaft opposite the solenoid side, which should move--not much, an eighth inch maybe--when the solenoid is activated. If this lever moves as expected it would confirm the solenoid, lever, shaft and cam are operating.

- the mechanical 'switch' that regulates pressurized oil has a tiny hole in it. I believe it's to allow pressure relief when the OD is switched off, but I'm not sure (anybody?). If this hole got plugged, it would cause problems, but I'm not sure exactly what. That is the reason, among others, that the ODs have both a fine oil screen and some magnets to filter the fluid before it enters the pump.

- as others have suggested, lack of adequate pressure would prevent the pistons from overcoming the very strong springs that keep the OD out of OD--'locked-up' with the annulus--when not selected. As would worn seals on the pistons. Later ODs, like my BJ8's, used O-rings to seal the pistons; earlier versions used metal rings not unlike the engine pistons (and the OD accumulator). I suspect the problem with the earlier design is that the steel rings wore into their aluminum housings causing leakage and loss of pressure. The O-rings I replaced in my OD showed minimal wear at almost 200K miles and the piston bores were pristine.

- the second test your mechanic should have performed would be the aforementioned pressure test. I think earlier specs called for min 350 PSI or so, while the later units spec'd 400-450. If your mechanic did not perform this test--and report the results to you--he was remiss. The pump that produces this pressure is a very simple piston-type, with a ball-type check valve which needs to be properly installed and seated, just like the activating valve. Significant leakage in either would not allow the OD to engage.

- the pump is what's known as a 'positive displacement' pump, in that it will continue to produce pressure to the point of destruction--unlike, say, a centrifugal pump which will 'stall out' beyond a certain pressure--and needs a pressure relief system. In a deNormanville OD, the relief system is the accumulator; pressure pushes against the spring(s) in the accumulator until the accumulator piston gets pushed back to some small holes that allow the oil to bleed back into the system (hence, max pressure is determined by the spring(s) in the accumulator). If your accumulator is worn--AFAIK, all had pistons with three metal rings--it would not allow pressure to build sufficiently to overcome the springs. My accumulator showed visible wear in the bore, and I replaced it with a DWR uprated unit which holds a greater volume of oil causing the OD to activate almost instantly.

- the OD has a cone clutch which, when activated, locks against a brake ring, which locks the sun gear allowing the planetary gears to revolve around it driving an outer 'annulus' which overruns--hence the word 'overdrive'--the planetary gears increasing output RPM. If this cone clutch is excessively worn the OD will not engage, at least not reliably. Replacement clutches are hard to find, all I found was rebuilt units from DWR (complete with core and shipping charges; other suppliers may have them but the DWR catalog has the prettiest pictures--Healey porn winking smiley). Fortunately mine, even at 200K miles, had plenty of 'meat' still on it so I reused it. If the brake ring was sufficiently worn this would cause similar problems.

Finally, you say your OD has 'never worked.' Do you know if the previous owner had the gearbox/OD out for any reason? A common error--well, I made it--is to not put the cam that drives the OD pump in the right orientation. Again, your mechanic should have suggested this possibility to you; at any rate, this should get fixed when you pull the gearbox to replace the clutch.

The Denis Welch site has some good photos of the OD components: https://www.bighealey.co.uk/healey-overdrive



Edited 1 time(s). Last edit at 2018-05-19 03:45 PM by Bob Spidell.

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