Next weekend when I drop the trans to install a new southbend I'm installing fast coolers and a trans temp gauge also. What should be considered hot for these trans? I'm running royal purple syncromax if that makes any difference. 

Same as any other oils, try and keep the temps under 230-240. If you pull hard you will be amazed at how hot manuals get and how drastic shifting down one gear makes in temps. When I worked at the gear shop we had numerous customers who pulled heavy and routinely melted the gears and bearings of the input shaft. Totally amazing to see. We got to the point we installed temp gauges on most manuals we pulled when we saw this happen and customers would come back in amazement as to what they saw and how much money they could have saved themselves in  repair costs had they changed their driving habits based on trans temps.

Both Nv5600 and Nv4500 one gear down from top is 1:1 direct ratio. Drop another gear it's possible to create heat. Temperature gauge on the transmission is well worth it.

 

My ISSPro EV2 has the warning light programmed for 220*F. Running 50wt Mobil Syn GL4

Edited November 7, 20177 yr by Mopar1973Man

51 minutes ago, Wild and Free said:

Same as any other oils, try and keep the temps under 230-240. If you pull hard you will be amazed at how hot manuals get and how drastic shifting down one gear makes in temps. When I worked at the gear shop we had numerous customers who pulled heavy and routinely melted the gears and bearings of the input shaft. Totally amazing to see. We got to the point we installed temp gauges on most manuals we pulled when we saw this happen and customers would come back in amazement as to what they saw and how much money they could have saved themselves in  repair costs had they changed their driving habits based on trans temps.

Ok that's what I was thinking but wanted to make sure, that's what I keep an eye for in my th400 in the mud truck too.

I usually run in 5th pulling any heavy weight to help prevent really high temps so I don't have to deal with melting bearings or gears together and I'm glad I have been!!

37 minutes ago, Mopar1973Man said:

Both Nv5600 and Nv4500 one gear down from top is 1:1 direct ratio. Drop another gear it's possible to create heat. Temperature gauge on the transmission is well worth it.

 

My ISSPro EV2 has the warning light programmed for 220*F. Running 50wt Mobil Syn GL4

Glad I've been running 5th then when I pull a trailer. Sounds like imm be running roughly 210* range just to keep things safe.

Direct always runs cooler than overdrive. So for nv5600 yes 5th gear is cooler than 6th. Funny part is both transmissions are the same in the top two gears.

Edited November 7, 20177 yr by Mopar1973Man

I towed with mine in 6th regularly in the flat lands and even on slight grades 2% or so and less as long as it would hold speed at near 50% throttle. Anything more than that I would go to 5th. I did adjust some after getting the trans temp gauge and seeing the temps but not a lot.

Like myself I've towed fairly heavy as well and used 5th (NV4500) quite a bit. As long as I'm not lugging the engine and trans temp is not getting high.

That makes me feel better then about towing in 6th then the times I've done it. Glad I only did it only did it highway though when I could keep it up in higher rpms. It's good to hear others have done the same.

Let's say towing in top gear for me being 5 speed and all the scare of the 5th gear nut... I never had a single issue with the 5th gear nut. I did snap the main shaft in half at the 3rd/4th shift ring. As for temperatures the only time I seen the warning light was towing on 115*F day up 7 mile 7% grade and did it in 3rd gear instead of 4th gear and the transmission got up to 225*F which was 5 degrees over my set point of the light.