Does anyone know how hot a manual trans get when drag racing? I don’t imagine it gets hot as an auto using ATF. I'm using 75W140

 

What gearset are you running and what oil because if that's stock gearset and your running gear oil you won't like the outcome. Needs to be lightweight synthetic gear lube or motor oil viscosity.

Trans temps after making back to back passes in my car were 170ish taking temp off the trans case but I think that was heat soaked some from the engine block.

 

With your times @ 170 +/- back to back i would be ok. I'm working on a custom part for inside my trans and it has a heat rating of 240 degs so it will work.

 

Temp needs to come from a sensor inside the trans, shooting it off the case isn't accurate.

I've not done it on a drag car, but on a sub 200whp road race car after a 25 minute session in 90* heat, it was 312* F.

 

I agree I just don't have a temp sensor in my trans so at least trying to keep some sort of record. Extended periods will hear the trans for sure.

 

Drag cars barely heat the transmission up - not enough extended load. It's mostly heat soak from the engine. I was getting 115-120 F fluid temp with mine (400 hp / low 11-second passes) - and that was it starting at 100ish F before the passes. Hell, the highest temps my car saw were highway driving for over an hour. :p

Road racing, dirt oval, etc. will get it up over 250 F even on the lower power set ups.

 

Imo trans fluid temps make the difference. For example we have a consistent mid 9 sec car that uses a stock gear set and has lasted a long time it sees no street duty. On the other hand we have 700 hp car that runs the streets and eats trannys all the time, both cars have decent power control but the street car drives an hour to the spot before doing the deed... I have no solid data to support this but when we pull the street cars case it always seems as if everything is melted. Just some food for thought.

 

What power/torque are BOTH engines?
What are the weights of the two chassis?
How much driving does the 700 hp car do during the street drive?
What transmissions (I presume both are stock gear sets)?
What fluid is being run in each transmission?
What suspension components / suspension designs?
What tires?
What clutches?

There are way more variables in effect than fluid temp (which you admit to having no data on) to go from correlation to causation.

 

has any one considered doing a micropolish of the gears and shafts in the trans. Ive done this to all my transmissions and love it. I have also noticed 30-50 deg drops in temp on customer roadrace customer cars its a treatment thats well worth the cost. I have a guy that does them pretty reasonably if you cant find some one to do it locally send me a PM

 

https://fbcdn-sphotos-b-a.akamaihd.n...12746174_n.jpg

here is a pic of a trans before assembly

 

No they are different weights, different tires, lots of differences but I'm just saying it seems like the actual driving of the car is what is heating things up and making them more susceptible to failure.... basically I was agreeing with you lol