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Transmission/OD Lubricant

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66ejag

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I'm trying to decide if I should put AMSOIL synthetic Manual Transmission Fluid (MTF), SAE 5W-30, into the tranny/OD of my BN7. It appears that this fluid has been developed specifically for manual transmissions, and the description indicates that it is compatible with brass synchros. Fully synthetic oils usually operate at lower temperatures in transmissions and have a considerably longer service life, although this latter fact is not an issue. The A-H has approximately 90,000 of unabused miles. Any and all comments would be greatly appreciated.

Ed
 
Last year I put Redline MTL in my BN1 gearbox. Sadly I didn't flush it out well enough and within 5 miles my laygear had chipped teeth. My guess is that something sludge adhered was set free to cause mayhem. That was an expensive (and I don't want to admit to myself as to how) learning experience. Although most everything else in that gearbox was already in need of replacement.


The guy who supplied me with the rebuilt swears by 50W racing oil (at least for a BN1).
 
Hi ED, Just use a good high quality single viscosity motor oil.I suggest Valvoline VR1 ; 30, 40,50 or 60 weight oil.--Fwiw-Keoke
 
BN1L_156424 said:
Last year I put Redline MTL in my BN1 gearbox. Sadly I didn't flush it out well enough and within 5 miles my laygear had chipped teeth. My guess is that something sludge adhered was set free to cause mayhem.
Click to expand...

I'm having a hard time making the connection between the Redline MTL and the failure. Please clarify, as I am sitting on 5 unopened quarts of newly purchased Redline, which was pretty highly recommended by others on the Forum.
 
I just put redline in my gearbox and only have 50 trouble free miles. I did have the gearbox and the overdrive apart to whitness clean insides. I believe the true design target for redlin is to hold up under extreame gear and bearing loads. We have none of these in our Healeys. I have used redline for many years in supercharged engines, heavy towing rear end and trans application with out an oil-related failure.
 
Hi Dave, I am not here to defend Red line MTL as my Healey gear boxes do not like it. However, I doubt that the MTL oil played any direct part in the failure of his gears,probably was just a coincidental discovery which may have been somewhat masked by the previous heavier oil.--Fwiw---Keoke-?
 
BN1L_156424 said:
Last year I put Redline MTL in my BN1 gearbox. Sadly I didn't flush it out well enough and within 5 miles my laygear had chipped teeth. My guess is that something sludge adhered was set free to cause mayhem. That was an expensive (and I don't want to admit to myself as to how) learning experience. Although most everything else in that gearbox was already in need of replacement.


The guy who supplied me with the rebuilt swears by 50W racing oil (at least for a BN1).
Click to expand...

My BN1 has ~ 3 qts of Redline MT90 in it and 1 quart of non detergent 30WT oil in it (because my mechanic and I didn't communicate properly, DOH!). I have driven it this way now for ~ 2,000 miles with no problems... in fact the car shifts like a dream.

You DEFINITELY do NOT want 50W racing oil in any healey gearbox with OD because if you use the OD when the motor is cold you will run the risk over time of bursting the pump piston seals in the OD. This is a bad idea, and I am suprised your rebuilder would suggest this. My guess he rebuilds them, but he doesn't drive them.

/bcforum/images/%%GRAEMLIN_URL%%/hammer.gif
 
/bcforum/images/%%GRAEMLIN_URL%%/nonod.gif I Run Valvoline VRI 60W in the summer and 50W in the winter if its cold been doing it now going on 20Years. Plus, I guess you know they normally run at 490 PSI--Keoke???
 
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Run Valvoline VRI 60W in the summer and 50W in the winter if its cold been doing it now going on 20Years. Plus, I guess you know they normally run at 490 PSI--Keoke???
_________________________________________________________
DITTO...by the book!
 
I don't blame the use of redline for my laygear dieing, something hard had to have killed it. I think it was more that it needed a rebuild and completely new fluid freed up something that was floating around but was trapped under decades of sludge. This just sped up the process a few months.
 
"Something hard had to have killed it"-- /bcforum/images/%%GRAEMLIN_URL%%/yesnod.gif--Over 40 years of hard usage. Crunched first and reverse, shifting---Keoke
 
Redline it is, until next season anyway, I'm anxious to see, or rather feel, what the difference is with the oil that's been in the gearbox.
 
I am interested in 156424's comments about chipped laygear teeth. I believe this is a very common failure on BN1s as they have notoriously weak second gear. There were two types of gear-sets used in BN1s, the difference being the helical angle of second gear(actually third if you regard the 'box as the 4-speed it really is). I have suffered the failure of the gear itself on two occasions and the remnants from one gear almost fitted into the gaps of the earlier failure. The alternative gears with the different angle seem to suffer the same failure but it is the laygear which fails. My question is: At what point in production did Austin change the gears? My Healey is a July '54 build and close in ch. number. And lastly, are these gears available from the parts suppliers? They weren't when I last tried to obtain them.
 
My mechanic offered me a laygear, I did some research at the time and I found that cape international, and a few other places had some available and I think it may be possible to have them reconditioned. According to my parts book it may be possible to replace the laygear the with later type if you also replace the first motion shaft and the 3rd speed Mainshaft gear. In Clausagers "Healey Restoration Guide" the later laygear and gears would have shown up in Mar of 54 ~154000.

When mine bit the dust, it was really one of those I changed the oil on saturday, put a few miles on it, but on the way into work thursday I heard a light ticking in second that got progressively louder. But I can't say there was a bad shift or anything else that set it off.
 
Seems there never is anything in particular that breaks the gears... my second gear on the laygear broke just sitting in the garage. Drove in the day before, all was fine. Took it out the next day and it was making a horrid noise as soon as I started down the street. Thankfully I was close to home so I just put it in first and parked it back in the garage... only damage in the box was the missing tooth so I have a good box if I can ever find a very early laygear....

/bcforum/images/%%GRAEMLIN_URL%%/whistle.gif
 
Well by the looks Red Line MT-90 seems the most for oils used. Followed by a straight weight oil.

Whats everyones thoughs on using a a gear oil? like a 80w90
 
Hi Adam,
RL MT-90 is a synthetic gear oil. It is rated as GL4 which means that it does not have the sulfur that is found in GL5 rated gear oils. Sulfur is thought to damage the bronze synchros in the earlier AH transmissions. Late AH transmissions had steel synchro rings.

The viscosity of RL MT-90 is rated as 75W-90 gear oil. This is the same viscosity as a motor oil that is rated SAE 40 & 10W-40. Different viscosity rating systems for gear oils & motor oils.
D
 
after reading everything i can find on oil in AH tranmissions, i think i'm going to go find some RL MT-90 to put in it. seems to be the best fit for it.
 
Adam -

I have MT90 in both my BJ8 and my BN1. Love the stuff. Shifting is great with it. Also, since the oil is synthetic it has a very long shelf life.
 
Straight 30 if you have overdrive. It is proven. It works. You won't be the first one to use it for five years or ten for that matter.
 
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