Convertor lockup shudder!

N

nate

New member
Joined
Apr 6, 2008
Messages
751
Having an issue with what I think is my convertor clutch.


When it locks up, let's say at 45mph and I'm not on the throttle hard... like the speed limit is 45mph... the truck shakes like I'd be driving on a washboard road.

Get off the pedal and it goes away, get on and it comes back. If I get on it hard, no shudder though.

Any ideas on what's going on? It's a built trans with a good converter (what Ultimate Trans uses) that is supposed to hold 600hp. It is a single disc though.
 
Definitely sounds like converter shudder to me. I would start by checking the fluid levels for sure. The fact that it only does it when under light throttle makes me think it might be a line pressure issue. You may try wiring the line pressure wide open, then take it for a quick drive to see if it helps.
 
Mine started doing the same thing when I was towing my boat down to the ramp last month. Try doing it with the OD/off button pressed, since the converter locks sooner, it should shudder even more.

I got rid of the shudder by replacing the converter.
 
my truck was doing the same thing when I was pulling my race car trailer up a hill. The converter was bad and also the od clutch was in bad shape. Went with a Goerend converter, added some more clutch discs and the valvebody tweaked on. Truck shifts nice and hard now.
 
It sounds like low line pressure to the conveter lock (over drive) up you need to have a gauge put on the trans by a good trans shop and have them check line pressure the good lock up under hard a throttle tells me you have some sort of pressure leak or poor line pressure rise could be valve body , pump ,or bad seal or just a bad conveter hard to say with out driving
 
sleepin-sport said:
Try doing it with the OD/off button pressed, since the converter locks sooner, it should shudder even more.
Click to expand...

Not necessarily. Its very possible that it might not slip at all in 3rd, but slip in 4th. Theres much more stress on the converter in 4th vs. 3rd.
 
Does it in 3rd as well as 4th. Not sure about 2nd, I'll try that (I can lock the convertor in 2nd)
 
teddybear said:
Not necessarily. Its very possible that it might not slip at all in 3rd, but slip in 4th. Theres much more stress on the converter in 4th vs. 3rd.
Click to expand...


Keep in mind that I was talking about running it with OD/off button selected (towing) which would lock up in 3rd as that is the final gear (no 4th)
 
My truck does close to the same but all my tranny parts are new and goerend. The carrier bearing is worn in mine causing driveline shutter at about the same time yours is. You may want to check the play in the bearing the rubber around them wears and allows movement.
 
I don't have one, quad cab short bed.

The trans was built and I've been running it since early summer 2007. About the only thing I've changed that I'm wondering if it has something to do with it is I switched to Schaeffer synthetic trans oil this summer.
I was running Walmart Supertech Mercon III before with no issues.
 
Mercon doesn't have the friction modifier that the newer Mercon V does. So if the new trans oil meets mercon V then you might have some slippage across the converter. Anyway you can datalog engine rpm and input shaft speed? We do this on the Fords to monitor slip across the converter. RPM and ISS should match if the converter is locked.
 
try dumping a bottle of RED LubeGuard in your fluid to see if that stabilizes your trans fluid. If your pressures are up and fluid is good and you still have a shudder, then you have a warped disc in the converter where the lockup clutch applies to and you need a new converter to fix it. I've been there done that 3 times now.

Lavon
 
every trans diesel trans builder I ever talked to stressed using RED LubeGuard.

Lavon
 
I am getting ready to change the transmission fluid in my truck. I was going to add Lucus transmission additive to it. I do some towing so should I add the red or black LubeGuard. It looks like the black stuff is better according to the chart on the link above. What are your thoughts.
 
I was told that the Black has too much additive and makes the fluid to "slippery" and can actually cause your trans to slip in performance applications.
If you have close to stock power levels then I don't see the black being a problem.

Lavon
 
I guess I should have posted that. I am stock other then an airfilter and soon a straight pipe but I don't think that would matter.
 
Well it calls for 1oz per quart. Bottle is 10oz and my trans holds around 18 quarts so it's a fairly low dose so to speak.
 
i use the 1 of black bottle.

DTT recommends the red.

Dave at georend says either is good, red or black.

Dusty at HTS recommends ATF+4, no lube guard.
 
You must log in or register to reply here.
Back
Top