Convertor Lockup

[Johnny5]

How can you tell when the TC is hooked up and when it isn't? I am just getting used to how this truck tows and I am not sure when I could be hurting the trans. When should it be hooked up and when shouldn't it be? I have noticed when cruising at 70mph towing and going up a hill that lugs the motor, I turn off OD and the speed falls way off (60mph and then the motor comes back to life) and then it seems like it doesn't want to get the speed back. Although I don't go with heavy pedal pressure to compensate, Is this normal since I in essence drop down a gear coming out of OD? How should I handle the inclines? More pedal? I just don't think to much of turning off OD before the hill and losing all my momentum, plus the big drop in speed sucks in traffic. I only tow 4-6k. I know these are a lot of questions but you guys can be short and sweet if you wish. Any knowledge is better than none.



Johnny5

 

[Jim Fulmer]

I will be up front with you first, the only way to cure this is to get rid of that stock complete piece of junk converter, you could go with anyones converter and be alot better off. as far as kicking it out your stock and not hauling much so I would say no lower than 1700 in O/D locked while towing up a hill, I could say to put an unlock switch in it but you would get no where with the converter, that's were good fluid coupling comes in on different converters.



Jim

 

[phoekema]

converter advice

I will agree with JFulmer. Bite the bullet and replace the stock converter. Believe me, it makes it a completely different truck, even if you don't do any power increases. May I suggest ATS, BD, Goerend, Suncoast... ... . I have ATS and think it's the greatest, but since you are not pulling any mega-loads any good aftermarket converter will make a tremendous difference. At the risk of pushing a vendor too hard, just let me add that the ATS converter is one that will lock up solidly with stock pressures, so you can put off valve body upgrades etc until later. Good luck with what ever you chose!

 

[Fireman Dave]

Johnny,



This is an ongoing debate - the OD vs no OD thing. I have essentially the same truck as yours. My TT weighs about 6k - maybe more. I tow with OD off all the time and it works great for me. The engine is really in a sweet spot in 3rd with the 3. 54 gears. It just seems to be lugging in OD, so I keep it off. I have no problems climbing hills or anything. I experience the opposite of what you describe. I find I have more power with OD off and the RPMs up. You can tell when the TC goes into lock-up - it sounds like it shifts to another gear once it's in 3rd. The transition to lock-up in OD is much quicker and a little harder to decipher. I also see my trans temp drop when the TC locks up. I have stock power, by the way. Good luck.



Dave

 

[WyoJim]

jkostera... . Mine is a '98 and it may shift a little different than yours, but I will tell you how mine shifts.

It has 1st, 2nd, 3rd, 3rd OD, 4th and 4th OD available to work with. I don't fool much with the OD button and it don't use 3rd OD unless I do, which would be on a 6% or steeper hill with switch backs where my speed has to stay down below 40 or 50 because of the switchbacks. On these hills I can keep it in 3rd locked up and the transmission runs a lot cooler, Also my mileage doesn't suffer as much. Or when I am coming down that hill I will light the OD light by pushing the button.

Out on the interstate if I leave the button alone (and I do leave it alone) it shifts like a 5 speed, and the shift into 5th is when it locks up. If I am not on the throttle hard enough the 4th and 5th shifts happen at the same time and when I was stock the engine would bog. with the EZ it don't bog.

Any speed under 70 if I floor it it will unlock, or if I let off the throttle it will unlock. Above 70 it don't unlock, it just runs all the way to 115 which is as fast as I have run it.



Your TC is not a POS but will get to slipping because the line pressure is not high enough at light throttle. Mine began slipping and I installed a DTT valve body, which cured it. $375. You can also increase the line pressure on the stock valve body. I think Bill K. tells you how on his web site.



If you do decide to play with the OD button, let off the throttle before you do. Mine gets all confused if I don't.

 

[Chipstien]

Since I have 4. 10's I can't really even suggest how to shift your trans. But I will say this, if your towing and drop below 1800 rpm's you would be smart to turn the OD off. With higher VB pressures you could go about 150 rpm's less even. A whole transmission upgrade is the best but then that is pretty pricey.

 

[pwr2tow]

Johnny, welcome to the TDR.



If everything is stock the best way to drive it is with your foot on the floor, remember your truck is a diesel and not a gasser. With your foot close to the floor you have more HP, more transmission line pressure, more rpm's to keep momentum moveing up hill. I would suggest that you lock out OD when you come to any hill you think the truck will bog down on.



EDIT:: the only thing bad about driveing with your foot close to the floor is fuel mileage will suffer.



When locking out OD push the button and slowly push the throttle down close to the floor so your rpm's will match your speed and that way you will not slow down as much and loose all your momentum for the hill.



With everything stock Your transmission is alot stronger than most of what you read would have you beleave. Changeing to a after market converter just to have lockup will do nothing for you unless your TC is slipping already, Lockup is Lockup no matter whos TC is in your truck, It's the 0 to cruiseing speed and people running higher HP that benefit from a aftermarket TC.



Turning up the line pressure a little is the best thing you could do for the transmission, don't go crazy with line pressures as some modified valve bodies can do. You can up the line pressure with a pressure lock or a mildly modified valve body or a shift kit.



Everything I said is for a stock transmission and stock to an extra 60 HP engine, after that throw everything out the window and upgrade the whole transmission.



Ron

 

[Lsfarm]

Falls off to 60 mph?

Johnny5: my truck with 3. 54 gears and auto trans can run above 70mph+ in third gear. It sounds like from your description that you are holding steady throttle pedal position and letting the truck speed fall back to match the throttle [power] pedal. Just keep the pedal down! One of the nice things about the 3. 54 gears is that you can tow at 70 mph in either 3rd or OD [4th].



As far as the lock-up goes, if you double punch the OD button, the TC will disengage the lock-up for a few moments, but not downshift to 3rd. This will show you what the truck feels like when the TC locks and unlocks.



If you want to turn up your trans pressures, there is a how-to page on the DTT website: www.dieseltrans.com this will supply higher pressures to hold the clutches [gears in auto trans's] engaged. I did this when I was stock, before I installed the DTT TC and VB, and the trans shifted a little firmer, and a little later. Once the new DTT Valve Body was installed it was preadjusted for higher pressures.



If you stay with stock power, your trans should hold up well towing 4-6000#, just pull those hills in 3rd and mid 2000's rpms. Low rpm with all the torque of the Cummins is rough on the auto trans because the low engine rpm can limit the availabe pressure to hold the clutches engaged, or the TC locked up. Slipping and a new trans will result.



Keeping the rpm up will provide the trans pressures needed to hold the clutches engaged, and there is more power available up to 2700 rpm.



Hope all this helps. Greg L

 

[Hunter11]

Welcome J5, I told you this would be the best $35. 00 you ever spent.



Hunter

 

[98rammer]

as for the torque converter, it is a piece of junk imho. it's a V10 tc with a stall speed of 2200-2400rpms---way out of the torque range. the stall speed should be between 1600 and 1800 rpms. if you notice, it takes a lot of throttle to move. if you have driven one with a modified transmission, you'll notice that any blip of the throttle with jerk the truck ahead. this is obviously only important when unlocked.

 

[Mopar-muscle]

the first problem , you are stock , sorry to say it but as delievered from chrysler the cummins is a joke , and you are not towing that much .



the stock TC is another problem , the stall is closer to 2700 rpm , you need a TC capable of putting the power to the ground unlocked , there is one that does it the best ... .

 

[Snow man]

Johnny5,you can install a tiny LED,and wire it into the Torque convertor circuit,this will tell you when the TC is locked up. You should be able to feel it lock up,especially with a stock Torque convertor,they are way to loose. The only way to totally fix the transmission is to have a full upgrade done to it,the valve body,new TC,and internal upgrades,while its out. I have the 89% DTT ,and towing with it is a dream,transmission temps stay low,and the power is transfered to the wheels much better than stock. I swear by DTT ,but there are others who have similar upgrades too. Go into the archives,and search functions,and read up,and go with what you feel is best if your going to fix this transmission once and for all.

 

[Jim Fulmer]

Johnny5

These guys are correct about the stall, when I had my transmission done with the current mods except a #8 plate (230/605) I could power break mine to 2800 without spinning a tire, try that now and it goes to 1600 and overrides those big brakes and rolls the tires over into smoke..... couldn't be happier... ... DTT Rocks!



Jim

 

[chuck3]

The best money you will ever spend on your truck would be to have the DTT or another good trans. mod installed.

 

[Johnny5]

Thanx for all the replies. I could get in to transmission mods and would like to, but heck if I had the cash, I would install all the goodies. Right now I am starting off with the basics, service manual, all the nice gauges just to be able to get a base line for the truck and learn about it. Being a new truck, I figure I'd use up the stock stuff before upgrading.



Lsfarm. . I think you hit the nail on the head I don't really give it more juice. With my diesel experience (heavy equipment) it has been all low rpms, seeing the gauge go to 2400 on my truck got my attention PDQ. I guess I should put more faith to the power curves I have seen.



Snowman... do you by any chance know how to wire one up? I think that you can't just hook an LED up w/o another component or two. That would definitely help learn what it feels like.



When can I expect this truck to go into lockup? From what I gather it is steady pedal pressure.



Thanx again guys... . This site is awesome!!!



Is there such a thing of "TDR addiction"? Must be, at one time while lurking I convinced myself that "12v vs. 24v" was a reference to voltage. I knew what 24v meant before that.



johnny5

 

[Lsfarm]

Engine RPM

Hi Johnny5, I understand your initial feelings about engine rpm. I've become used to the idea of turning 2500-3000 rpm. But every time I see a photo of the connecting rods on these Cummins engines, I cringe at the reciprocating mass of those six huge connecting rods and pistons at 3000 rpm.



But never fear!! the 12v guys are turning 3-4000 RPM!! And I haven't heard of any connecting rods being launched to the moon on an otherwise healthy engine.



Also the 24v trucks with 4. 10 gear ratios are running a lot higher revs/mph compared to our 3. 54 gears, and there are no problems [except for maybe slightly lower fuel mileage].



I would just turn up your transmission pressures, this is real easy, email me if you want, send me your phone #, I can talk you through it. This will help preserve the health of your trans.



Your TC will unlock everytime you back off the throttle, and relock after you reapply throttle. This is in 3rd [OD locked out] or OD I found this to be pretty annoying, and am glad that I don't have it anymore with the DTT smartbox. Everytime the TC locks up, there is some wear on the small lockup surfaces [especially when under load]. This is the main weak point or most common failure in the stock transmission.



I hope all this helps, are you going to come to Muncie?



Greg L [the Noise Nazi]

 

[KatDiesel]

I run 2500 to 3200rpm alot, its fun to drive with overdrive off.



Also when drag racing I can see around 3600rpm on the 3-4 shift.

 

[markgrif]

I don't see Banks Engineering mentioned much on TDR. I'm new to diesels and was wondering if the Git-Kit would help on some of the problems in this thread. In reading the lierature it seems like it would.

 

[Greg Boardman-RIP]

Johnny5, Welcome to the TDR. I have found that I can see my truck go into lockup on the tack. It shifts into 3rd, then it locks, stays locked and grabs OD. The PCM controls the 3rd to 4th shift. Running uphill with a stock truck the only time I shifted out of OD is when it was hunting for the sweet spot. On a hill with the small amount of weight you are pulling just mash it to the floor. YOu wont hurt your stock trans. I sometimes pull in third at 55 mph over hills. I can hit 60 but our trucks start to defuel at higher rpms. That might be why you cant bring speed up. Us alot of speed at the bottem of the hill to carry you over the top. As for mods, I know it is expencive. But, I will wave as I fly by on those 6% grades. Maybe throw a line Greg

 

[Johnny5]

lsfarm....

Are you part of the GLTDR? Was thinking about joining up with them. I like the idea of going on a "cruise" with the group as well as getting together for the "bombing". Although, I would probably just be watching the other CTD's get it, but I would help if I can. We may go to Muncie, problem is I want to get to know some guys first so I don't get down there and hang by myself. Also, it is hard to be at a track and not do any racing cause I race my snowmobile on the 1/4, I miss that right now. This year I am passing on the Summit Super Series to be able to get some boating and possible TDR kinds of stuff in. Muncie sounds like a good start. Are any of you Northern IL & Southern Wi guys gonna be there?



Johnny 5



Wooo Hooo... just got my TDR newbie pack!Oo.