Engine/Transmission (1998.5 - 2002) torque converter shudder

[crpdstr]

I'm a new member and was wondering what to do about my 2001 cummins with auto, only mod is power edge ez. When it shifts and locks up it shudders pretty bad and even worse with a trailer. Went to the dealer and they couldn't duplicate the problem and said nothing is wrong. any help would be great.

 

[hawkerpilot]

try a lower jumper setting ,they come from the factory for max fueling, they start to fuel at 3 psi of turbo boost. A lot of power at low rpm. s without a lot line pressure for the tc to have a firm lock up.

 

[Snow man]

Pull the EZ off the truck,or get a modified valve body put in it. You will toast the transmission if you continue to drive it like this.

 

[chuck3]

Is it slipping? Shuddering is caused by overheating and warping of the mateing surface. The damage may allready be done.

Shortly after mine shuddered a few times it started slipping.

 

[StakeMan]

His signature shows a DTT transmission.



EDIT:

Sorry, I read the wrong signature line.

Originally posted by hawkerpilot

try a lower jumper setting ,they come from the factory for max fueling, they start to fuel at 3 psi of turbo boost. A lot of power at low rpm. s without a lot line pressure for the tc to have a firm lock up.

 

[Swamp Donkey]

Steak,



I hope you are not trying to stir something up! LOL

 

[StakeMan]

Not stirring the pot. Just trying to help.

 

[crpdstr]

Did I open a sore subject ? I will take the power edge off and give that a try, I would like more info on trans modes to cure this, not planning on other engine mods,but like the driveabilty with the power edge on the truck. I am aparently not the only one to have this problem. thanks for the input.

 

[Briar Hopper]

crp-dstr, valve bodies are available to increase the line pressure in your transmission. The stock transmission is very marginal on holding the stock power levels, in most cases. Adding power, like with an Edge, doesn't help.

There's a lot of competition right now, a lot of people posting on these forums that have an opinion on one brand or another of aftermarket transmission products. So, yes, unfortunately, it's a sore subject, and that makes it hard for the members to get unbiased technical evaluations to help them decide.

Look in the Links section of this website, there is a sizeable list of transmission vendors you can call. A few phone calls to the right people will get you taken care of.

 

[barryg41]

OEM transmission Shudder

I too have a shudder at light throttle from my transmission. But I have found better ways of using the go peddle to rid almost all of the shudder.



When I leave from a red light, I get RPM's up to 2k and keep it there till lockup. (out of OD) Then when I get above 65 I put it in OD. But what if I launch say at 1500 rpm. Is the transmission line pressure lower at that rpm or is it the same at 2k? I have a shudder when shifting at a lighter throttle, but at 2k the shudder is gone or almost gone. I also noticed that the transmission temp stays lower when easin up to 2k and getting it to lockup sooner than later. Which of course means no slippage. At least I hope so, the trans temps show that it is not slipping.



Most of this is pulling a 5er and I also drive the same way when running around town empty.



What I need to find out is, at what RPM do you achive maximum transmission line pressure. Then I could launch at that RPM. I am not in a hurry to get to 70, I just want to get there with the least amount of fluid drive time with maximum line pressure and into lockup.



Is this the right way to treat an OEM transmission? Maximum line pressure at the right RPM to get to lockup then ease up to crusin speed!



I'm into to towing not hot rodding. No slam on the hot rodders!

 

[Snow man]

Barry,you should get your line presures up,by way of a valve body,or a couple turns of the pressure screw at least. The reason your slipping at 1500 is because the engine has more torque there,and they low throtte position only allows low line pressures,the higher RPM's requires higher throttle position(in turn giving higher line pressures),which combined with inertia holds theTCC,and clutches better. Your driving techniques are the key to long transmission life,keep the RPM's up,the transmission and engine will live a long happy life. I do know that line pressure does not change with RPM's(at least on my truck),but governor pressure changes with vehicle speed,and line pressure changes with throttle position. From the limited testing Ive done, line pressure is a few psi higher when the trans is cold.

 

[LSMITH]

Snow man is right, keep the RPM up and the throttle heavier. If you want to kill a stock transmission in a hurry baby it around while towing with added power. You are better off slapping the carpet with the pedal than lumbering up to speed at 1500 RPM.



barryg41, you are doing the right thing by getting up to speed quickly. You can go a lot harder on the throttle too, say 25-2600 RPM, over that and temps seem to come up quickly. I would second what Snow man said about turning up the line pressure, get it up to 64 PSI or so. DTT had the instructions on how to do this up on their website, but I am not sure if it is still there.



crp-dstr, do not let it shudder. It is damaging the transmission every time it does it. Get the line pressure up or take the EZ off. If it is shuddering with just an EZ odds are the line pressure is low anyway and it needs addressed even at stock power levels. Internal leakage varies quite a bit from transmission to transmission, some are fine with an EZ and some are not. It looks like you got one that needs some attention to run just the EZ.



Hope this helps.



EDIT: the shudder is not necessarily line pressure being low, but on a relatively new truck it is the most likely cause. If it still shudders when the pressures are adequate professional intervention is necessary.

 

[RPurdy]

I have been going thru the process of getting the "Shudder" out of my life. Had Auto-loc, & Torque-loc installed so the exhaust brake would have significant effect. Then added the Edge EZ and found that under heavy load (accelerating up hill or pulling the fiver and getting up to cruising speed) the TC would not hold the power and----Shudder insued. So the next thing was to replace the valve body. Now the power gets to the pavement without the vibrator effect. Whoopie here we go towing



Dick

 

[Hummin Cummins]

TTT

I just got back from a camping trip today and for the first time I had this same shudder problem. Crusing along at a good clip, come to a hill and ease into the go pedal about 15-1600 and it happens. Shakes the whole damn truck. My only choice then is to knock off the OD and then go up the hill. It has only done this twice, I know that eventually I will have to replace the TC, but will a valve body take care of it for now? I can scrape togther the $ for that but not for the whole works.



Chris

 

[DWest]

shudder

Hummin Cummins: Mine started to shudder at 16000 miles so I took it in to the dealer and they checked the trans. fluid and it was totally broken down, almost black. They said they recomend a flush at 13000 mies so did that at $109 and shudder went away. Black trans fluid does'nt seem like a good sign to me of a healty transmission. I used to service my Chev at 25000 miles and the fluid was always pink. What a pitty that DC put a motor like the Cummins in a otherwise great truck in front of such apoorly matched transmission setup.

 

[Hummin Cummins]

DWest

I'm on about 1000 miles with this fluid and filter. I change them once a year. It still looks nice and purple (LE 7500). The level is up and it doesn't smell bad. The other thing I noticed is the transmission didn't get hot when this happened. It was running about 125* (sensor is in the pan)



How much do we add to the temp for a reading in the pan?

Mine has never been over 150* and that was sitting idling.



Chris

 

[RADdodge]

I was told, by someone who should know, that when you put a big load on the transmission in OD, it should be kept at or above the peak torque RPM which is about 1750 rpm. For me, that translates to around 60mph. If I can't keep it above that on a hill, I shift out of OD.