dmentzer

I just changed the gear lube in my 66 Muncie from the old thick, brown, stinky stuff to the Valvoline 80-90 GL5 gear lube. The Valvoline was much thinner than the stuff that came out. The only problem is that the shifting has gotten a lot stiffer and requires much more effort to do, while driving, of course. This is the only change made and clutch is adjusted properly. Is there any other lube made that will help the trans shift easier? It almost feels like the synchros are not stopping the gears and that you're shifting without the clutch. Any help is appreciated.

lovevettes

There is person here in New Jersey that has been rebuilding and buying Muncie gear boxes for over 35 years, I bought my new parts to rebuild mine myself and I asked him what gear lube he would recommend.

He said if you use synthetic lube you will have the best lubricated case around, [the fluid gets slung out of the gears, onto the inside of the case] he recommended a climbing gear lube like the Lucas gear lube [Advance use to have a small set up on their counter that had two small plastic gears with a small handle to rotate the plastic gears showing how the Lucas oil climbed , they also had a setup without the climbing oil, for comparison]

A freind of mine that I met at a cruise nite complained about hard shifting I told him what the rebuilder said , he put lucas oil in his 1959 Corvette 4 speed and the following week came over and shook my hand and thanked me for the info. I have it in my 1960 vet. and like it.

bweaver999

I assume you simply removed some gear lube and added the Lucas oil? I saw the display at a Strauss Auto near me, it does seem interesting. Do you know if it might quite the syncro's?

lovevettes

bweaver999,

It is not an additive , you replace the whole amount, It is 80/90 gear oil and it comes in 32 Fl. Oz. bottles

try it, it might quiet the trans. It is worth a try.

MidShark

From what I understand, you do not want to use a GL5 gear oil in your old Muncie (or B-W) tranny. The GL5 has things in it which are not kind to the sychros. I finally found some of the correct GL4 gear lube at NAPA. It was called Sta-Lube, and it was only in half-gallon containers.
The GL5 is fine for your differential, (no brass parts) but not your tranny.

Rich

ghostrider20

I use Lucas 80-90 but it is not a synthetic oil, and carries a GL5 rating.

I serviced my trans with synthetic the first year I had the car, and after a week, I sucked it out and went back.

The shifting was horrible, it was not stiff, but I had to float almost every gear to avoid snychro noise and grinding.

Mark

bweaver999

Is this guy in North Jersey? Could you PM me or post some details on the shop? My synchros are a bit noisy, will probably try the Lucas first but may need a good re-builder near me.

lovevettes

Street-Wise Performance
973-786-7500
Andover,New Jersey

Ask for Richie

SWCDuke

The oil spec for all GM manuals of the era is Mil-L-2105D -same as the axle. The current commercial equivalent is SAE 80W-90 GL-5.

The "brass corrosion" from the sulfur-based EP additive in GL-5 is way overblown and is only an issue at very high temperature - beyond the typical operating temperature range.

Millions of these transmissions had a good life on the original spec lube - and many probably still have the original factory fill after 40 years - so why start experimenting.

If it works don't fix it.

Duke

dmentzer

I don't know what is in the Valvoline 80-90 GL-5, but I do know that it has caused my trans to be very hard shifting. The Valvoline was very thin and clear compared to the fluid that came out. When I saw the difference between the two, I wished I wouldn't have changed it. I am going to change to the Sta-lube GL-4 and will report back with the results.

SWCDuke

The reason why the old fluid was thick and dark is because it's probably been in there for 40 years. I suspect your shifting problem has nothing to do with the fluid change, but whatever you say...

Duke

GCD1962

In the past 40 years there have been many improvements in lubricants. Can't see anything wrong with trying the Lucas products. No need for tradition if there is something better out there

dmentzer

Well, my trans shifted fine before this change. So, since my time is free and the fluid is cheap, I am going to find out what the problem is. Maybe I do have a trans problem. And, this might be the way to find out.

ctjackster

dmentzer - since you have nothing to lose (I was in your shoes a short while ago, synchros getting all noisy, wondering if I was looking at a tranny rebuild project) i would suggest you try this before jumping off the deep end:

Assume the GL5 oil in there is fine (it is, and it sure beats the molasses you took out). Evacuate half of it, and replenish with this stuff:

http://www.lucasoil.com/products/dis...tid=2&loc=show

that's Lucas "Oil Stabilizer" Since the unit doesn't take a full 48 ounces, you won't be putting the entire contents of the 24 oz bottle in when you replace "half", but a substantial portion.

drive your favorite back country roads, where you are working the gears some. (in other words, it might not be an instantaneous fix).

See if this doesn't put things quiet.

I can only tell you that, while I am not a believer in snake oil fixes, I was in your shoes and got a post from a forum member ("EWJ") suggesting I do this, and I thought, "what the hell, nothing to lose, next step is pulling the tranny." As for me, and maybe this is just confined to my own Muncie, my tranny is now quiet and shifts as it should. That was a year ago.

I know folks might weigh in with how foolish this sounds, etc. but I can only report my own experience.

edit - just realized I had referred to the product as tranny fix, when it was Lucas Oil Stabilizer that I used with great results.

EWJ

Not to hi-jack..can someone advise the drill size and tap to convert my M21 to having a drain plug? Thanks!

mrg

Seems 'experience' can, at times, go both ways. The GL-5 in my Muncie worked just fine - no issues.

ctjackster

this thread is where I posted up about my synchros getting noisey and the topic of adding a drain "plug" was discussed some:

http://forums.corvetteforum.com/show...cie+ctjackster

dmentzer

I guess my hardheadedness ( is that a word?) won't let me believe that it isn't a fluid problem. My trans was perfectly fine before I did this change. No shifting problems, no noise. I still don't have any noise. But the harder I get on it, the harder it is to shift. Never had a problem before. So, I have to do something to satisfy my need to try and find a solution. I'll find the problem one way or another.

ctjackster

ok, well, you can always try the stuff I did.

But swapping out your old, black goo for correct, as it was delivered with oil, likely didn't harm anything. Maybe just let things spin free-er than they were before, perhaps.

bweaver999

In the thread, you mentioned you replaced with non-synth lube but still had the problem. Is the Lucas the non-synth and got better over time or did you change again to that and it fixed the problem?