For those towing in 4th to reduce heat do you have a different gov spring? I can only get up to about 64 in 4th tops with a load. Gov starts shutting it down.

 

I was referring more to the engine temp and the need for a larger radiator since he stated that he had high coolant temps in 4th where the RPM's are higher than 5th. Going to a numerically higher gear will raise the cruising RPM in 5th. He also stated that he had tranny temp problems in 5th, not 4th, which I find totally believable. Heat of course is a coefficient of friction, when the output shaft is spinning faster than the input shaft in 5th(OD) maybe there is less surface area on the OD gears to dissipate heat? I don't know, I always hear all these warnings about towing heavy in 5th though. My old 91 non IC used to run hotter empty than any of my IC trucks, I think the larger crossflow radiator might be one of the most important things to have if you're going to tow heavy.

 

i have the non intercooled radiator(91.0) and i fully agree, but this will do nothing for the G360(Getrag(360) 5sp) that is running a fever! 245*

 

If you are running synthetic there is no reason to be spooked about 245 degrees in a manual trans. Worry when it passes 280.

If the engine is running hot in 4th I'd look into upgrading the radiator.

 

Ok let me go into farther detail. I have no choice but to goto a 4.10 or 4.56 gear, if for everything else, starting out. Starting on a decent grade with 3.54's and 27,000 lbs isnt easy on a truck, matter of fact Id guess Ive shaved a few years off my clutch. I do the exact same route every week, and the torque curve is what matters most to me. From testing different combo's, If I run 65 mph in 4th gear, and hit a long grade-yet not a steepo grade. Before long Im running 55mph, because Im not in the best area to make torque. However, if I hit the same grade at say 70 in 5th grear, I can carry the same speed up the grade until my EGT's get too high. I admit I need a better cooling option up front, and I need one pronto. But Time is also money, and Id rather run between 65 and 75 mph than 50 to 55 mph, which seems to be what happens in 4th gear.

As for my tranny temps, I cant explain it. 1st trip, I ran almost exclusive 4th gear and my tranny temps were around 200 or so. 2nd and 3rd trips I tried 5th where i could, and boom right up pushing 250*

 

As for my tranny temps, I cant explain it. 1st trip, I ran almost exclusive 4th gear and my tranny temps were around 200 or so. 2nd and 3rd trips I tried 5th where i could, and boom right up pushing 250*


Basicly when you are in 4th there is no load on the gears in the tranny, 4th=drect drive . one solid shaft (so to speek).all the gears are turning but there's no load!

5th puts a load on input,output,andcontershaft,front and back bearings, let alone all the gears that make up 5th!

IN short much more heat generated in 5th

 

Yep, that's where the friction comes into play - when those gear faces start gnashin' and bashin' the heat comes on quick...

 

Ok then let me ask this, is there a way to move my power band up in RPM range? I agree I would my rather run direct, and I also understand that 5th gear isnt the best, therefor once it starts to slow to around 60-65, I immediatly goto 4th gear.

If I can get this truck to pull hard in 4th gear, im set. My problem is, it wants to fall on its face at those rpm's

 

Short of a cam swap, no. Gears are way cheaper.

I think you're right to want to move to 4.10's. As you said, it will improve the startability, which is very important with the loads you pull.

 

3200 gsk would do the trick. didn't see your sig, though

 

Here's some thing to think a bout but way to much $$$$$ but still something to think about!

You first need to go the 4:10 gears like dave said,and it will help on torque or pulling power, thru every gear!


the 2nt thing would be down the road awhile......no pun intended cause thare, just under 3,000,... if you do the install your self! the 3 grand is what it will caust you to put an over drive unit on the back of your tranny...I chose the Gear Vender over drive!!!!

the point that i'm getting to here is that with the 4:10 gears you will tend to be in 5th even more often them you are now but pulling a way from a start will be much easer.

With the GV you can have a better gear ratio in over drive then you have pressent witch will give you better fuel milage on the flat.. I know I know, you don't care about fuel milage but the best part of the GV is that the 4(derect) and over drive(GV) is the same ratio over drive as 5th would be!
4:10 gears,= easer to pull away from a stop, and saves the clutch too) GV=better high way speed and milage to boot! I love mine, it work grate,like a hole diff truck!

Heres a chart to ponder on!

GETRAG 5-SPEED MANUAL
Axle Ratio
4.10 3.55 3.21 3.08
Trans Ratio Final Drive Ratio

that didn't work try this!

http://www.gearvendors.com/ddrive.html

 

Yeah, that would be sweet. How hard is it to put one of those things on, Flash? I'm getting about 20mpg on the highway with 4.10s. Gotta get the calculator out and figure out how many miles it will pay off with better mileage and start working on the wife for budget approval...

 

Ace:

I have a 1991 554and as far as I know it is stock. It runs great but runs hot on upgrades with a 8500# fiver. I have changed the thermostate to 180o and it has an extra tranny cooler but still overheats. So what exactly is a I/C radiator? and will it fit. Also where can I purchase one?

Thank You,

charliex

 

I don't mess with trannys much but I may have an idea to cool the "rag" while under extreme load. NASCAR uses tranny coolers on manual transmissions. I believe they install a pump that takes a suction from the drain and discharges thru a cooler and back in thru the fill. At least that is the jest of it. The automatic trucks have a cooler infront of the intercool just behind the condensor plus they have a "wet" cooler that is behind and below the turbo. Get a fan/hub assembly that is off an intercooled CTD if you haven't already. I have heard they flow more to handle the added heat load. ALso I would run a synthetic oil. They are slicker, offering more protection than dino oil, and generate less fluid friction. They are stable at higher temps as well.

 

I could only ge 17 with my 4:10 and now get 21 mpg +

it"s really not that bad. if it wasn't for the shorning of the rear drive shaft and and the wrong speedo adapter it would have only take a day to install!