Transmission fluid viscosity and converter stall

[karolko]

I am curious if anyone could enlighten me on the potential changes of more viscous/less viscous transmission fluid could effect stall speed SLIGHTLY.

I think i read something like this on yellow bullet, but i am unsure.

I have a 200 4r trnas with a 3200 l/u converter and i am running a pt70 turbo with 0.81 A/R. I know the converter is a little too tight, and as a temporary bandaid, i was hoping to change my fluid to see if i could loosen it up slightly.

Any input would be nice.

Thanks alot guys,


Adrian

 

[blackplague]

using fluid to tighten converters, not loosen

using a hydraulic oil like, john deere hyguard, citgo torque fluid and the like will tighten a converter from 200-450 rpm's (depending on the ratio to trans fluid). Whatever stall speed you have with dex 3 or type f is what you will have.

Mike

 

[buickruss]

Will doing this damage the tranny?

 

[blackplague]

No way!!

Will doing this damage the tranny?

No.

 

[Dusty Bradford]

Royal purple has a fluid that is very thin. I was tuning a car and had no drop on the gear change. I drained the Royal purple out, put tractor fluid in and it dropped 600 rpm on the gear change.

I don't know if it's thinner than type F or Dex 3, but it looks like water.

 

[karolko]

I think i need some clarification. From what i have read thinner fluid like tractor oil will tighten up a converter. Correct?

If this is the case, will a converter that normally stalls at 3200 stall at lets say 2800-2900? If this is the case, won't it just make spool up that much worse if you need a looser converter like i do in my particular case? (70mm and 3200 lock/up.

Basically, i think i am screwed. Until i buy a new converter that is.

Thanks for the help guys.

 

[lazaris]

I think i need some clarification. From what i have read thinner fluid like tractor oil will tighten up a converter. Correct?

If this is the case, will a converter that normally stalls at 3200 stall at lets say 2800-2900? If this is the case, won't it just make spool up that much worse if you need a looser converter like i do in my particular case? (70mm and 3200 lock/up.

Basically, i think i am screwed. Until i buy a new converter that is.

Thanks for the help guys.

The tractor fluid comes in a std and low viscosity. The std. viscosity (thicker) will tend to tighten up the stall. The low viscosity is more like the std Dexron transmission fluids. Synthetics which tend to flow better may loosen stall.

 

[Adam Connell]

So would this possibly hurt a transmission in any way? I got a stock D5 that I wouldn't mind loosening up some. Im in the market for a good 10in unit and a new trans, but could this be one of those "In the mean time" fixes?

 

[turbo nasty]

If its teh stock D5 doubt youll see several hundred rpms with different fluids

 

[deezdad]

Royal purple has a fluid that is very thin. I was tuning a car and had no drop on the gear change. I drained the Royal purple out, put tractor fluid in and it dropped 600 rpm on the gear change.

I don't know if it's thinner than type F or Dex 3, but it looks like water.

This sounds like a good thing? Many here think royal purple is snake oil, still reading up myself but seems they make good stuff.

 

[fastblackracing]

I am curious if anyone could enlighten me on the potential changes of more viscous/less viscous transmission fluid could effect stall speed SLIGHTLY.

I think i read something like this on yellow bullet, but i am unsure.

I have a 200 4r trnas with a 3200 l/u converter and i am running a pt70 turbo with 0.81 A/R. I know the converter is a little too tight, and as a temporary bandaid, i was hoping to change my fluid to see if i could loosen it up slightly.

Any input would be nice.

Thanks alot guys,


Adrian

When I was playing / researching this stuff last year I was able to find enough technical data on all of the
available trans/hydraulic fluids that are commonly available to help make some better educated choices.

You are wanting to loosen the converter so will have to find a oil that is thinner than what you have now
and will still hold up to the heat and abuse or turbo regals will put on the oil....you may not have many choices
to choose from but once you know what to look for you will be able figure it out better.

And with this data you can do some comparing of the oils differing viscosities that will impact the
converter stall speed up or down compared to what oil you now have in the transmission.

You will find under the technical info The oil viscosty rated as "Kinematic viscosity", along with a rating
at 40*celsius and also at 100* celsius. The later rating at 100*c is what you would use to compare
with as this temp is close to what temp our transmissions run at when up to normal operating temperature and with some time and effort you can find this info for most any oil or trans fluid out there.

In general through my research I found reports of stall speed adjustments up or down ranging from
150 rpm to as much as 600 rpm or so.

And this is the flash stall of the converter not the power brake stall when you are trying to get the turbo
up on boost....this power brake stall speed change up or down will likely be a lesser amount than
the flash stall which happens when the engine making power and is the rpm speed that the engine
falls back to on a gear change.....or is the rpm that the engine goes to once you launch the car at the
race track. In my case my 18 blade ptc converter had a flash stall of 5300 rpm using the thicker redline
racing ATF. My power brake stall was 3600-4000 rpm.

I also found trans oil viscosities at 100*C Ranging from a low 4.2 [ watery thin ] to on the high side 13.4 [ thicker ].

There is a wide range of trans oils/ tractor oils for wet clutch use/ and even some compressor oils that were very thick out there.

I found some high powered 2000hp+ turbo guys using the amsoil 40 weight thick compressor oils
to tighten there converters with great success.

I ran the redline racing synthetic ATF which has a 100*C rating of 10.0....in my 200r4 to tighten the converter
which it did about 150-200 rpm over regular dexron 6. Not sure if the 2nd gear band liked it or not as the band failed very fast with 9.70 power put to it, but the 3rd gear clutch pack looked perfect tho so I am not sure what happened there.

So this particular trans oil I copied and pasted below is rated at a viscosity of 7.1 @ 100*C.
from this number you could compare different oils to get an idea of what direction the oil you are considering would shift your stall speed either up or down......How much it will change is hard to say since the converter type and the amount of Horsepower you are hitting the converter with will vary greatly.

This amsoil super shift racing fluid is what I was running once the 2nd gear band was replaced
but unfortunately my testing got cut short so I am not able to give any data comparisons between
the Redline rcaing ATF and The amsoil super shift racing ATF....I will say the Amoil super shift fluid
has a very different odor to it straight out of the bottle.

Hope this helps, FBR



Typical Technical Properties – AMSOIL Super Shift Synthetic Racing Transmission Fluid (ART)
Kinematic Viscosity @ 100˚C, cSt (ASTM D445) . 7.1
Kinematic Viscosity @ 40˚C, cSt (ASTM D4445) . 41.9
Viscosity Index (ASTM D227). 132 Viscosity CCS, cP @ ˚C (ASTM D5293) .4270 (-30)
Flash Point, ˚C (˚F) (ASTM D92) 246 (475) Fire Point, ˚C (˚F) (ASTM D92) 262 (504)
Pour Point, ˚C (˚F) (ASTM D97) -48 (-54) NOACK Volatility, % weight loss (g/100g) (ASTM D5800) 6.6
Four-Ball Wear Test, (ASTM D4172B @ 40 kg, 75˚C, 1200 rpm, 1 hr) Scar, mm 0.35