Towing in overdrive

   / Towing in overdrive #11  
Pat... your not running a completely OEM motor/electronics are you???
I had EGT & boost guages at the time and EGT never saw 1200 and it was pre turbo. Truck was completely OEM except for guages and exhaust brake.
 
   / Towing in overdrive #12  
a manual in OD is fine. I normal ran my wrangler in OD hauling sleds, it was something else that broke the clutch years later. I did try running 4th once. it made no noticable difference hauling the 102" wide one, never tried it with my other trailer.

I did notice a high milage crown vic give me worning signs after hauling the small trailer. its the autos that can cause a problem. even then, I don't think its a big deal if you are in flat land. I've cought myself in OD and not tow/haul a couple of times when hauling my really big trailer behind a half ton. The tranny is still here, but I can afford the extra gas easier than a burnt up tranny right now, so I don't risk it. I think its more that hauling a trailer in OD can be the little extra that pushes an iffy tranny over the edge.

as for bogging down the oil burners, it can be done, but they excell at high torque low RPM. its more to do with how much do you want to downshift.
 
   / Towing in overdrive
  • Thread Starter
#13  
I've got a short haul today about 60 miles with the same trailer. I'll keep it in 4 th as much as possible and check the mileage, I'll report back here tonight and let everyone know.
 
   / Towing in overdrive #14  
Like jagyzf said-- see if you can find a torque/hp graph for that engine, and try a few different rpm points to see if there's a difference.

A turbo would favor higher rpm, but that's not an issue for your engine, so it boils down to personal preference and driveability-- but there may well be a "sweet spot" that does best at combining efficiency & power.
 
   / Towing in overdrive #15  
Aren't they great? Mine's never seen more than 190* on the hottest days.

Other than DP's GM that everything broke on, just about everyone else that owns & operates an Ally loves them. Mine feels like a tank. I wish my 4800 had an Ally. :(




I'm assuming your's is a ZF-5 manual. They have a .77 O/D on the close ratio and .76 on the wide ratio transmissions. In 4th, you're running 1 to 1.

My question is-did you check the fuel economy when you were in 4th gear?

Never had a single issue with the Allison. It was the only bright spot of my 05, the Dmax and the rest of the truck were junk. Must have been built first thing on a Monday. That being said the Allison did not like heavy loads, say 12,000# or more with surge brakes. The Torque Shift handles surge brakes much better. The problem was in the down shifts. That may be solved now with the 6 speed and paddle shifter?

Chris
 
   / Towing in overdrive #16  
Pat... your not running a completely OEM motor/electronics are you???
I had EGT & boost guages at the time and EGT never saw 1200 and it was pre turbo. Truck was completely OEM except for guages and exhaust brake.

I have no "ELECTRONICS" per se as the truck in question is a '97 Dodge/Cumins, the last of the 12 valve-no computer plain vanilla Cumins in the Dodges. I have a pyro-EGT, boost gauge, and tranny oil temp.

The engine is stock but came with the HD valve springs which support greater retarding force capability with the exhaust brake.

The performance mods are: 1. replaced stock injectors with injectors having much finer holes, and 2. replaced injector pump with one that has considerably higher injection pressure. This sort of evens out and I spray about the same amount of fuel as stock but in a much finer mist which supports more complete combustion. I get increased HP and Torque AND at the same time a little increased mileage.

How can I get more HP AND better mileage? More efficient, i.e. complete combustion. I'm using the fuel more efficiently not just producing smoke like some "turned up" rigs do. A cost of doing business like this is the need for vigilance in monitoring the EGT as in the heaviest working situations you can force it to overheat. Mind you that if you let up a little bit and only ask the engine to produce a moderate amount of power above stock it will never overheat. Only when you go b---s to the wall for a reasonably extended period will it tend to dangerously overheat as indicated on the EGT. Heavily loaded towing up a steep grade I can drive by the EGT and pull the hill way faster than stock and not overheat.

Before I learned to be more moderate I twisted off the input shaft of Dodge's poor little under engineered 4 speed automagic tranny.

I have a Gear Vendors "Over/Under Drive" an auxiliary overdrive unit mounted to the output of the xfer case. This gives me 8 forward speeds (can't use it in 4wd but don't need it then) This essentially gives me "half steps" between each stock gear. I find that 3rd over is a very useful gear. The big gap in Dodge's transmission between 3rd and 4th is like having a missing gear. If you can't hold the load on a hill using 4th you have to slow way down to run 3rd. This is where 3rd over is so neat.

Lightly loaded and not pulling steep grades you can put it in OD-OD, i.e. 4th gear (Dodges OD) plus OD in the aux unit. Doing this gives about 85 MPH at 2000 RPM. This Cumins is happy at 1700 RPM which gives you just a tad over 70 MPH (about 72) which is a good deal for 70 MPH interstates.

When it comes to a few RPM or a MPG or two versus lugging the engine or straining the tranny, I prefer to opt for what is easiest on the equipment. In the long run harsh treatment of the equipment will result in more cost, less reliable service, and more down time. You'll never be able to pay for decreased MTBF with the fuel savings you might (just might, not a sure thing) get by abusing the hardware.

Pat
 
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   / Towing in overdrive #17  
I've got a short haul today about 60 miles with the same trailer. I'll keep it in 4 th as much as possible and check the mileage, I'll report back here tonight and let everyone know.

That would be good to know because at 1700RPM, you're actually a lot closer to the max torque rating of 1400 RPM on an '88 7.3L.

2200 RPM should consume more fuel and take you well out of your torque curve.

The ZF-5 speed was OK, but the ZF-6 speed was a big leap forward.

Interestingly, GM started using the ZF-6 in 2001 up until a few years ago in the GM-HD. The GM version of the ZF-6 was improved over the Ford version and had a few more features than the one used in the Ford Superduty. With the NV5400, the ZF6 might be the best light truck manual trannies ever built.

Light reading on the german made ZF transmissions: http://www.mackstrans.com/ZFID.html
 
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   / Towing in overdrive #18  
i roasted the auto trany in my 92 4runner towing in OD. I even have an aftermarket cooler and temp gauge. I noted it starting to slip, kept watching my temp guage, nothing.... kept getting worse so i dumped the OD and within about 10sec i had pegged the gauge and came costing to a stop.

The old trannies (like mine) were advised to never tow in OD. The new ones are built with extra coolers, extra kickdown features "tow/haul mode" IMHO it really doesnt matter on new trannies. (unless you have aftermarket chips etc that boost your hp another 300hp and your towing at or over max cap)
 
   / Towing in overdrive #19  
Never had a single issue with the Allison. It was the only bright spot of my 05, the Dmax and the rest of the truck were junk. Must have been built first thing on a Monday. That being said the Allison did not like heavy loads, say 12,000# or more with surge brakes. The Torque Shift handles surge brakes much better. The problem was in the down shifts. That may be solved now with the 6 speed and paddle shifter?

Chris
Only problem I've ever had with mine was more a factory problem. I had one where the flexplate wasn't correctly tightened at the factory and cracked the plate and ate the input seal. They also did a valve spring job at the same time that now keeps the OD out until 35MPH. Old one would allow it to come in at 30MPH. :(
 
   / Towing in overdrive
  • Thread Starter
#20  
I tried running it in 4th gear but gave up after 10 miles. It's just easier running in overdrive, it seems like running it at 2200 rpm is to fast for the motor, and the water temp was going up, it was about half way up the scale when I started using overdrive and after that everything worked just fine. There was only a couple of bigger hills that I had to use 4th for. I think that being the torque curve being at 1400 has a lot to do with it. Next thing I'm going to install will be a pyro so I know how hot I'm actually running. I was thinking of putting a turbo in this truck, but I'm hesitant because I don't want to cause more unforeseen problems.
 

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