What about towing in 5th gear with NV4500 ?

[JPLB22]

I did a seach on this topic but didn't find anything that answered this question directly...



Is it O. K. to tow uphill in 5th gear with an NV4500, if you can keep the rpm's above say 2000?

I will be towing about 4000#'s up a long 6-7% grade, and I was thinking that with my new EZ the truck might be able to hold about 70 mph. But to do 70 I'd have to be in 5th. I have 3. 73 gears and at about 25-2600 rpms in 4th I can do 65 mph. But I would like to do 70 if the transmission can handle it.



TIA



Jeff

 

[SRadke]

You'll do less transmission work in the long run if you shift down to 4th and run at 24-2600 rpm. My general rule of thumb is keep boost below 20 psi in fifth if I intend to hold it for any period of time.



-Scott

 

[Joseph Donnelly]

It would be a good idea to put in the fully splined mainshaft and 5th gear kit from 800-std-tran or another vendor. Staying over 2000 helps minimize the vibrations and torque spikes that loosen 5th.

 

[BVoltner]

towing in 5th gear is ok if rpm is held above 2000 but be careful not to lug the truck down. Lugging the truck down will result in 5th gear backing off or breaking. Note remember to over fill your transmision. also check your gear ratio it is probably is 3:54 or 4:10

 

[JPLB22]

Thanks for the replies ! I'd love to here more too !



I like the idea of keeping the boost below 20 psi while in 5th. That seems to be a good way of keeping the load on the transmission while in 5th under a certain point.



P. S. What do you mean by overfilling the transmission ?? You just poking fun or what



Jeff

 

[R C Cola]

Overfill

They are serious. This transmission tends to run a little dry on some of the bearing surfaces when pulling hard up a grade which causes the oil to tilt in the bottom of the transmission. It helps cooling and lubrication especially in 5th gear. I added the coolers for a little extra oil and cooling. The method is... fill to the inspection hole ,replace plug, then add a full quart from the top thru the shift tower. I added a wire to the plug to remind me not to pull it and lose the extra oil. I use the top bolt on the inspection cover to be sure I have enough oil in the transmission. Good Luck... R C