Uphill Towing Blues

[Tim Hayosh]

A question for the group.



When towing my (approx) 7500 lbs. TT up steep inclines (6%+), the transmission goes into this wierd pattern of shifting VERY rapidly between 2nd and 3rd gear. Obviously I don't let this continue more than a couple of oscillations before I vary the throttle and loose speed. When it does this, it hits HARD from gear to gear.



So, is this an adjustment thing, a normal thing, or what? Has anyone else experienced this? The truck only has about 5-6,000 miles on it. See sig for BOMBS (None. )



Any input is appreciated.



Thank, Tim

 

[dewdo]

Tim:

I had a 94 that would do that and never solved the problem, but after hanging out on this site I have discovered things that can be done to overcome this problem.



One possibly quick easy fix would be a VA box, and a boost module and elbow. That would give you a little more zip and possibly keep it from hunting all the time for a better gear.



A DTT valve body and torque converter would definetly help out.



I have those items on my rig right now and I can take a 6% grade in 3rd gear pulling my 15,000 lb fiver with no problems. Went over the Tehachi Summit and I don't think it ever shifted out of overdrive.



With the crappy transmissions DC has put in our rigs, a person has to improve it some if you want to tow or haul.



Dewdo in the other Washington

 

[Tim Hayosh]

Dewdo, thanks for the reply. Unfortunately, I don't believe you can put a boost elbow on a 2001 (HY35 Turbo). Second, I don't think I should have to invest in an after market product to make my truck work properly within Owners Manual specs.



Although someday I really would like to put in some BOMB stuff, I don't want void the warranty. There is little doubt that the first thing I'll do is put in all the good DTT stuff, I just don't want to have to do it 4 months after buying it.



My biggest fear is that something is misadjusted, and I am doing harm to the rig and not knowing it. Obviously something isn't right when I'm heavy going up hill, but what about unloaded?



Anyone else?

 

[Dieselnerd]

It doesn't sound right to me. Mine has never done what yours is doing and that was when it was bone stock towing a similar weight trailer. I wouldn't try to diagnose yours online since several things can cause hunting between gears. One thing that does come to mind is the kickdown adjustment may be off. I assume yours is still under warranty and if it was me I would take it in to ensure the adjustments and pressures are correct. There are a couple of transmission guru's on this forum and they may have some better ideas. I would not live with it and that kind of heavy shifting back and forth won't do your driveline any good either.

 

[Joe G.]

This may not apply because mine is a '95. I had the exact same symptoms and it turned out to be the TPS (Throttle Position Sensor). If you don't get it fixed it WILL damange your transmission. It took a while with mine before the damaged parts failed, but when the failure happened it needed a new TC, pump, and flex drive plate. The hammering caused the flex drive plate to fracture.

 

[WCrovo]

My 99 did it from day one! The reflash was supposed to cure it. It was a little better but not right. On mine it was the TC slipping, although I didn't know it at the time. I didn't complaine right away because I was PISSED about the brake pull they could't fix, and that they could duplicate. The way my auto ended up I would stat complaining now and often till it is fixed.

 

[Steve M]

My '95 auto did this once. We were climbing a 7% grade with traffic and curves slowing us to 35-40mph. I had locked out O/D and this let the TC lock up in 3rd. I told a mechanic friend about it and he said they'll all do that. His Chevy gasser does it too. He said it's time to pull it down to second and let the rpm run to the governor. I did this for awhile until it dawned on me that if I left O/D on, it would keep the TC unlocked in 3rd. That solved that problem. It was a simple problem of me not knowing how to drive an auto and help it decide what it needed to do.

I traded the ''95 auto for a '98 5spd. That was great to be able to tell the transmission exactly what I wanted it to do and it did it. It also cost me $260 for a master cylinder at 80,000~ miles and I was always leary of the 5th gear nut failing while we were 900 miles from nowhere. And it chattered and grabbed sometimes making for some less than desirable parking and launches from stops after long hot runs with a load. Throw money at it? That's the roaring complaints I hear about the autos. I guess it's a toss-up.

So I traded my '98 5spd for another auto/3. 55. It maintains boost under full throttle at 2100rpm (sweet spot) and out accelerates my 5spd/4. 10 no matter how fast I could shift. When I get to the mountains with my new truck, I'll have alittle more experience to decide what to do if this one gets confused at that 40mph 3/4 throttle point of indecision. Pull it down to 2nd and let the governor do it's job. Not sure what this one will do in 3rd with O/D left on as it locks up the TC in 3rd either way.

 

[Bill Kondolay]

Tim,



It sounds like your kickdown cable is out of adjustment, since this problem occurs with the trailer on while climbing hills taking it back to your dodge dealer or a technician will not prove helpful unless it is PCM or TPS related.



When customers come to our shop one of the things we teach them is how to do a kickdown cable adjustment simply because it varies between a loaded truck and an un loaded truck.



Keep in mind it will also vary with hp, since yours is a 2001 truck the adjustment is very easy and requires basic tools.

#1 Phillips screwdriver, (a stubby one)

med size flat slotted screwdriver

and one friend



what we are going to be looking for is a one to one movement between the engine throttle and the transmission kickdown cable.



As the person in the cab starts to step on the throttle , the kick down cable at the transmission should start moving.



At full throttle in the cab the kick down cable at the transmission should be all the way back with only about 1/16th -1/8th " left.



In other words you should not be able to move lever on the transmission back by hand more than 1/16 -1/8",

3/16 is still ok , 1/4-1/2" is not acceptable.



A little side note for you 12 valve guys , this is also a good way to check and see if your engine throttle cable is stretched.



24 valve guys- in order to adjust your cable undo the 2 phillip screws that hold the black plastic cover in place.

The plastic cover is located just above your fuel pump.

Press very gently on the plastic screws, if you apply too much pressure you will not be able to undo them.



There are 3 cables going through the bracket, the bottom with the white retainer on the back side is your kickdown cable.



To unclip the plastic clip, simply hold the throttle lever firmly with one hand so it doesnt move and then with the other hand slip the plastic part of the kickdown cable forward and it will unclip from the fuel pump throttle.



With a flat bladed screw driver squeeze in one of the little fingers that lock the cable into the bracket, at the same time lift in the direction you are squeezing the finger from. Repeat the same proceedure for the other side.



A lot of guys find it easier to use needlenose pliers to squeeze the fingers.



Bring the cable to the master cylinder it is easier to make the adjustment there.



Mark your starting point on the kickdown cable before you make any adjustments, bright colored nailpolish works really good.



Remove the white colored locking mechanism adjusting the cable forward(more slack) will make your transmission shift earlier,



Moving the cable back will make your transmission shift later.



I will see if i can get stefan to post some pics on monday to make this a little easier, it is much easier than it sounds.

 

[Steve M]

Boy do I feel dumb. Tim, scratch my idea and follow Bill's lead. I remember the tubular kickdown rod on the ol' 727s. I've played around with them trying to make it perfect in my old Mopars. I didn't realize we could still do that with the 47RH and 47RE. And to think I removed my pan and installed a temp sensor while doing a transmission service. If the crank would have fallen off in my face I probably wouldn't have recognized what it was. I must be blind. I could have made my '95 shift later like my '01 does? All those miles wishing it would shift later, downshift sooner and blaming the TPS and PCM... OH NOOO, I'm Charlie Brown.

 

[Tim Hayosh]

Bill, and all: Thanks for your input! I'll definitely go for the kick down adjustment as described above. I won't being towing under loaded conditions for another 6 weeks, but I'll report my results in this thread.



Thanks again to all.