Overdrive Shudder

[Harry V]

Lately, my transmission shudders a bit when going into overdrive at low RPM/throttle settings. This seems to be more noticeable when the outside air temperature is cold and does not happen when driving the truck a little harder, i. e. shifting into OD at... say 55 mph as opposed to 40-45.



Any adjustments I can make??? I adjusted the bands at the last fluid change. (no... the shudder did not start then) The truck has 51K.

 

[blampright]

There is lots of info in the forums on this same subject. Just do some searches for transmission related words. Basically the stock torque converter can't handle much more torque than the stock engine puts out. So if you have any mods done like most of us do, the TC slips and that's the shuttering you feel. The reason it doesn't do it at higher RPM's is because there is enough pressure at higher RPM's to keep from slipping. It's at low RPM's the TC can't handle a lot of torque. Basically, keep the OD turned off until you're above 50mph. And you might want to plan in your future budget a new TC from ATS, BD, or DTT. <BR>

I plan on doing a whole transmission upgrade in the near future, haven't decided what brand to go with yet.

 

[Challenger-II]

You might also want to check out BD's Pressureloc which will mechanically turn up your line pressure at the lower throttle (pedal) positions. It is meant for stock or slightly modified trucks.

 

[B.G. Smith]

TC lock up

I think the pressure lock only turns up the pressure on deceleration. It pulls the throttle valve all the way forward which would cause the trans. to down shift if accelerating. bg

 

[Greg Boardman-RIP]

Overdrive shift is controlled by PCM. There is no adjustment. I disengage OD before it goes in. Then I shift when I get up to speed. That is if I am driving around town. Overdrive is for the hwy above 55. Sometimes mine will shift at 32 mph. that is way too low. Bill K said to go ahead and drive around all day in third.

I do it all the time. Low rpm's and not enough fluid pressure in tc is causing shudder. I think.

 

[Challenger-II]

Re: TC lock up

Originally posted by B. G. Smith

I think the pressure lock only turns up the pressure on deceleration. It pulls the throttle valve all the way forward which would cause the trans. to down shift if accelerating. bg

That is not how the Pressureloc works... . Here is a direct description from BD.



"A BD PressureLoc increases convertor lock-up clutch applied pressure on 1994 to 2001 Dodge trucks by 30% at light throttle pressure. The kit can easily be installed on the stock transmission and assists in preventing convertor shuddering and transmission slippage.



Torque convertor clutch slippage results in high heat and eventual transmission failure! The higher the HP, the lower the transmission line pressure is, because line pressure is controlled by the position of the throttle pedal. The diesel has so much torque at light throttle pedal movement and thus low apply pressure at the lock-up clutch when the engine is at its peak torque!



You can notice a shuddering torque convertor under throttle at low speeds, and also under heavy throttle with high power engines.



The kit’s function is to increase the transmission line pressure when the lock -up clutch is engaged. The PressureLoc cylinder rotates the transmission’s throttle valve shaft to simulate 3/4-throttle travel to increase the line pressure to 90% of what the valve body design can attain at wide open throttle. The resulting pressure must be measured and set when the kits are installed.



The PressureLoc is primarily designed for stock or mildly enhanced engine applications and owners whom have installed an exhaust brake and want some extra protection.



It is not a replacement for a modified valve body!



High horsepower and heavy-loaded applications should also be equipped with the BD Valve Body with larger porting for pressures up to 180 psi.



The PressureLoc increases the clutch applied pressure to 90% of what the valve body is capable of achieving at full throttle when you are only at ¼ to ¾ throttle travel. This kit addresses the need for more clutch holding pressure. "

 

[Texasdeere]

You may just need to change your driving tecnique a little. Anytime I pull a light load, and I don't throttle it enough, it starts to shudder.

CORRECT ME IF I AM WRONG EVERYONE... I believe the trans shifts 1st, 2nd, 3rd, lockup, then Overdrive. Just turn the Overdrive off and make an attempt to "put your foot in it" in 3rd gear until you feel the Lockup kickin, then if you are up to enough speed and depending on your load, let it go into Overdrive.

If your truck is shuddering empty, you may be "babying" it too much with the throttle. I you are empty just drive it a little harder

and it should stop shuddering. MY 2cents...

 

[B.G. Smith]

Re: Re: TC lock up

Originally posted by Challenger-II





That is not how the Pressureloc works... . Here is a direct description from BD.



"A BD PressureLoc increases convertor lock-up clutch applied pressure on 1994 to 2001 Dodge trucks by 30% at light throttle pressure. The kit can easily be installed on the stock transmission and assists in preventing convertor shuddering and transmission slippage.



Torque convertor clutch slippage results in high heat and eventual transmission failure! The higher the HP, the lower the transmission line pressure is, because line pressure is controlled by the position of the throttle pedal. The diesel has so much torque at light throttle pedal movement and thus low apply pressure at the lock-up clutch when the engine is at its peak torque!



You can notice a shuddering torque convertor under throttle at low speeds, and also under heavy throttle with high power engines.



The kit’s function is to increase the transmission line pressure when the lock -up clutch is engaged. valve body design can attain at wide open throttle. The resultiThe PressureLoc cylinder rotates the transmission’s throttle valve shaft to simulate 3/4-throttle travel to increase the line pressure to 90% of what the ng pressure must be measured and set when the kits are installed.



The PressureLoc is primarily designed for stock or mildly enhanced engine applications and owners whom have installed an exhaust brake and want some extra protection.



It is not a replacement for a modified valve body!



High horsepower and heavy-loaded applications should also be equipped with the BD Valve Body with larger porting for pressures up to 180 psi.



The PressureLoc increases the clutch applied pressure to 90% of what the valve body is capable of achieving at full throttle when you are only at ¼ to ¾ throttle travel. This kit addresses the need for more clutch holding pressure. "

z Sorry, my mistake. bg

 

[TURBOs4LIFE]

Shudder

Harry, My truck was doing the same thing as yours. I have the same mileage as you also. The dealer just replaced my torque converter and the problem totally went away but it probly will come back once I put a few miles on it

 

[Texasdeere]

Under normal driving conditions, and not towing, I agree with TURBOs4LIFE. It should not be shuddering, you must have a problem.

 

[Big_Daddy_T]

tc

torque converter problems lead to transmission failure very quickly if not addressed. A modified valve body is probably your best bet until you replace the tc. The transmission will not lockup in third unless od is locked out. lockup in od w 3. 55s at 55 is lugging anyways so i run in lockup in 3rd. I took off my 35s recently to address my rpm at 65. In the end i believe I will install a gear splitter so I can keep her in the sweetspot. You have all the gauges let the bombing begin.

 

[Texasdeere]

Harry,



You may have a low line pressure problem with your transmission that is in turn causing the converter to fail prematurely. If the dealer installs a new torque converter for you, they may want to check your line press before sending you down the road. My 2cents again... MH