ATF in a muncie?

[skwurl]

I had a discusion with this older guy who told me had converted his muncie so he could run ATF. ATF is thinner than gear oil obviously. could this be done and would it even be worth it?

[dana barlow]

no,viscaity is not there,oil for hard grear contect[standard tran.] must have thick to sofen the gear impack.......
Very thin oil is used for drag racing ,were low HP dose not bang the gears,giving a small drop in drag,but not good for high HP big loads.

[scottybaccus]

I did a lot of reading when shopping for my trans and never saw anything about ATF in a Muncie. I settled on a new M21 from Auto Gear Equipment. I am looking at the install sheet and it says:

" We recommend filling your new transmission with a good quality SAE90 gear lubricant meeting API specifications GL4 or GL5 AND MT1. DO NOT USE GL5 lubricants without the MT1 label; the EP additives in unmodified GL5 lubricants have been found to damage the bronze used in bushings and synchronizer rings."

[The Shocker]

What would be the point on a street car or cruiser ? As you said its thinner and more prone to leak than the thicker 90 weight ...

[skwurl]

Originally Posted by scottybaccus

I did a lot of reading when shopping for my trans and never saw anything about ATF in a Muncie. I settled on a new M21 from Auto Gear Equipment. I am looking at the install sheet and it says:

" We recommend filling your new transmission with a good quality SAE90 gear lubricant meeting API specifications GL4 or GL5 AND MT1. DO NOT USE GL5 lubricants without the MT1 label; the EP additives in unmodified GL5 lubricants have been found to damage the bronze used in bushings and synchronizer rings."

yea it sounded kinda out there to me. I'm running an m-21. i'm running sae 90. Thnks for the input.

[skwurl]

Originally Posted by The Shocker

What would be the point on a street car or cruiser ? As you said its thinner and more prone to leak than the thicker 90 weight ...

I would be more worried about burning the thing up!

[32v]

the getrag 5 and 6 speeds man. trans uses dextron 111 fluid same as atf about the same consistancy as 5-30 wt

[Bodacious]

Originally Posted by skwurl

I would be more worried about burning the thing up!

There are plenty of manual transmissions around that do use ATF or other lighter lubricants. But generally for reasons already mentioned, and/or unless it's been modified to use a lighter oil, it's best to stick with a manufacturer's recommendation.

[propwash]

I'd be inclined to think that unless the modifications include removing all bushings and putting EVERYTHING on HD roller bearings, ATF just wouldnt to the job at all. Not to mention the total loss of pressure cushion when the gears intersect with each other. I'm always amazed at the disinformation provided by folks that think that any modification used by racers (who spend a lot of time rebuilding after x number of races - so longevity is hardly ever an issue) must be a good modification for street use.

"wake me up early, be good to mah dawgs, and teach my children to pray"

dj

[Bodacious]

Originally Posted by propwash

I'd be inclined to think that unless the modifications include removing all bushings and putting EVERYTHING on HD roller bearings, ATF just wouldnt to the job at all. Not to mention the total loss of pressure cushion when the gears intersect with each other. I'm always amazed at the disinformation provided by folks that think that any modification used by racers (who spend a lot of time rebuilding after x number of races - so longevity is hardly ever an issue) must be a good modification for street use.

"wake me up early, be good to mah dawgs, and teach my children to pray"

dj

There are plenty of stock manual transmissions running around that have ATF factory installed. This is why I said in most cases, it's wise to stick with the factory type fill. HD OTR truck transmissions only use 50 weight oil. Believe it or not, high viscosity is not always the end-all of lube protection.

[BAD ROD]

I use ATF in my T56 6-speed. I don't know anything about it, but I bet you could modify a muncie to run on ATF.

Mike

[scottybaccus]

Propwash is correct.

ALL of the modern manual transmisions using ATF are using roller bearings. It won't work well in extended use in a bronze bushing transmission.

[Flat Ernie]

Originally Posted by scottybaccus

" We recommend filling your new transmission with a good quality SAE90 gear lubricant meeting API specifications GL4 or GL5 AND MT1. DO NOT USE GL5 lubricants without the MT1 label; the EP additives in unmodified GL5 lubricants have been found to damage the bronze used in bushings and synchronizer rings."

This is an important tidbit - it's harder to find GL4 products as time passes. The GL5 stuff works great in rears, but older trannys will be damaged if they don't have the MT1...

[C9]

Originally Posted by skwurl

I had a discusion with this older guy who told me had converted his muncie so he could run ATF. ATF is thinner than gear oil obviously. could this be done and would it even be worth it?

I'd be interested in what conversions he'd done.
Other than draining the gear oil and pouring in ATF.

I'll bet it was a secret and he wouldn't tell you.



My favorite one from days gone by was the guy who'd put Zephyr gears in a 55 Chevy transmission.

Or the guy who'd put an Olds crankshaft in a
flathead block.
that would've taken some serious engineering to say the least.
And, best part was the guy doing the telling had a hard time drilling holes with a drill press....


Micrometers hell!
I gots me an aluminum yardstick....

[btmatt]

Gear and bushing clearances are much "looser" than the newer transmissions. The older trannies need the thicker oil to absorb shock.

[wfo guy]

90 wt. was designed to absorb heat from normal running. All the older trans were sent out with this. I'm unaware of any reason to change this. My Tremec 3550 has a GM syncromesh oil that looks like 50 wt. It's still an older trans compared to any 6 speed. It's based on the Ford top loader 4 speed from the 60's. I wouldn't try anything lighter than that.

[draggin breath]

mopar A-833's left the factory with ATF.

[Flat Ernie]

The conversion to ATF-type lubricants in the mid-80s had as much to do with shift feel as it did anything else. All else being equal, lighter gear oil shifts easier - hence early Ford recommendations of 90WT in winter & 140WT in summer.

The NWC T5 originally called for 70-90WT gear oil, but all changed to ATF (even NWC) later...

I'd be leery of using ATF in any older-style trannys...(but I do run it in NWC T5)

[38fordcoupe]

Back in the mid to late 60's I knew a bunch of guys that ran ATF and a pint of STP in their "race only " 66 and 67 Nova's and Chevelles. It would warm up faster and shift nicer then 90wt. It was not recommended for a everday driver though. Don't remember anyone that "lunched" a tranny from using it.

[Ron]

A guy that used to be my neighbor worked at the trans plant for 30/40 years. I was telling him I had a Camaro with a t5 that blew up at 50k, that used ATF. He told they tried some t5's with gear oil instead of the ATF and he said the worked better with the heavier oil. He did not say what was better just that they did better.