transmission Problem?

[racokley]

OK, for you transmission guru's... My 96 has a "shudder" when it makes the final shift at about 50 mph, wheen pulling load or with cab-over camper on. If you feather the throttle as it reaches that point it shifts smoothly... Don't even notice it when empty, just with load and hard throttle. - I see that a lot of you have replaced the torque converter... Could this be the problem? Since it started doing this, it hasn't got any worse (probably over 2 years ago), but hasn't gone away either. There has never been any signs of heating or any chunks in the fluid at the service's. I have a guage on it, and three coolers... temp in pan rarely exceeds 150, even towing 30 ft 5th Wheel. - Any ideas would be helpful! Go easy on me, I really don't even understand how an automatic transmission works! Never had any reason to care before now! I just want to be able to hammer it to the floor, and not have to let up till up to speed!

 

[Joe G.]

Your sig shows a torqueloc. Those things are torque converter destroyers.

 

[Steve Roseman]

Install a switch to keep the converter unlocked, then when you are up to speed let up on the throttle and let it lock.

 

[MxerChris]

I have a similar problem when I have the OD off and it goes into lock up pulling my camper usually at light throttle (and rpms lower) there is a shudder, if I'm using more throttle and it goes into lock up at a higher rpm it doesnt seem to shudder, only at lower rpms. How does a switch work for the lock up? I assume you would leave it on when empty and only use it when pulling? One last question what is a transbutty I see advertised on some sights? Sorry to but in with so many questions, Thanks, Chris... ... ... .....

 

[Joe G.]

Chris,



The torque converter clutch (TCC) lockup happens when a ground is applied to the lockup solenoid and the hydraulic conditions are correct. Normally the CPM applies the ground and removes it for kick down. There are two versions of the manual lockup switch (AKA mystery switch), two positon and three position. The two position switch allows you to apply a ground to override the CPM so once the lock applies it will stay that way regardless of conditions. Easy to tear up expensive things with this thing. The three position switch also allows you to override the CPM and hold the ground, however it also allows you to prevent TCC lockup regardless of conditions. This is important if you have increased engine power. If your engine is makeing more power you can damage your TC before the throttle actually gets to the kick down position as far as the TPS is concerned. The best way to do this is with a TC Saver or Smart Controller from DTT. However, there are a few of us who use the three position switch with good results. I've been using mine so long now that I avoid stressful TCC situations without thinking about it. BUT I do NOT recommend the manual lockup switch to anyone else. The purpose for haveing some sort of mechanism to maintain lockup is for exhaust brake use. Preventing lockup is for preventing a strong engine from tearing up your TCC.

 

[Steve Roseman]

Chris,

Exactly what Joe said.

The switch is a poor man's setup like me

There isn't a good substitute for the right equipment, but I'll have to make do with what I have right now. I use the unlock mode of the switch more than I do the lock. I don't have an exhaust brake, too flat around here to need one and I don't haul a lot.

My wife calls it my passing switch, she knows when I'm going to make some noise because I reach down and unlock the converter. I figure I can get a lot more miles out of the stock setup if I relieve the lockup clutch of some stress.

TST has a diagram of the wire loom and which wire to use. They mention using it to improve acceleration times by locking the converter, I would recommend against that. The wire they show to be grounded is the one that needs the circuit broken to unlock. http://www.tstproducts.com/tranny_install.html



The transbuddy is a kit for the valve body.



P. S. TST says not to cut the B11 wire, you must cut it and reroute the circuit through a switch to unlock things manually.

 

[Joe G.]

Steve,



I've made a little "ease of use" modification to my setup. The ground wire from the switch goes to a push button on the floor about where a old fashioned dimmer switch would be. It's right against side panel instead of out in the middle. I made a bracket and mounted a door dome light switch in it. So if I want to temporarily force an unlock I just step on it. That is, to pass on the free way I step on the switch at the same time I stomp on the loud pedal. Look Ma, no hands!

 

[Steve Roseman]

That would work good Joe, I'm just afraid with my wife driving the truck occasionally it might get engaged and disengaged by mistake.

With it getting cold here in the midwest, I find it helps my warmup if I drive for awhile with the TCC unlocked, gives me a couple hundred more rpm.

If I'm not going too fast, OD off with TCC unlocked gets me up to operating temp in a hurry.

transmission temps unloaded aren't a problem when doing this.



Question for you Joe, which DTT TC do you have? Even though my transmission works fine, it doesn't hurt to plan ahead.

 

[Joe G.]

I think I have the 89%. I got mine just before the percentage was being quoted. The usage is normal driving with occasional towing. More towing after I retire. That's what I told Bill so I expect that I got the 89%. You can't believe the difference between it and stock. Same thing with the VB. It doesn't shift with a bang like the BD that it replaced, but nice and firm. The ability to lockup up in 2nd is really great. I live on a hill that has a crooked road that is mostly 9% grade with a couple of short dips. So I pull out of my drive way and go down the hill with it locked up in 2nd using the Pac Brake. No service brakes needed and the temp is starting up by the time I get to the bottom.



My floor push button is right against the side so you have to make an effort to push it accidently. If anyone else drives the truck I put the switch in normal position so that it works like stock and tell them the if they mess with any switches the panel is rigged to blow.



I've replaced the stock cup spiller with a custom made switch panel. A Geno's garage Cup Smoothy works better to hold cups and other junk anyway. No more coffee or pop on the carpet.

 

[Steve Roseman]

I've got the BD TC, don't know if it was rated or not. The previous owner had it installed before I got the truck. All I know is it's supposed to be a low stall.

I'm sure with the technology on the TC's advancing like it is, a new one from either manufacturer would feel better than what I have.

Under a hard load I still lose about 300-400 rpm worth of power through the TC.

Plan on going with a 3k spring kit from Piers which will help, but some transmission mods are in the future somewhere.

 

[racokley]

To Joe G.

Joe, you seem to know a lot about these things, but no one really answered my questions... It sounds like you seem to think my problem is in the Torque converter? Also, could you explain why you think the torquelock is a TC killer? I rarely use it, in fact I can't see much use for it... Thanks, Rick

 

[Joe G.]

Rick,



The reason for all these locking devices for the TCC is because an exhaust brake is worthless with the auto trans since the TCC unlocks after a few seconds of the trottle being in idle position. When you are pulling a trailer or hauling a heavy load an exhaust brake is great for helping on a down hill. However, if the TCC unlocks the engine drops to idle so the exhaust brake has no effect on these 2nd generation trucks. Russel Ward invented the first so-called mystery switch a few years ago. What it does is apply a ground to the TCC lockup solenoid so the TCC will stay locked regardless of throttle position. This way an exhaust brake really works! There is a fly in the ointment. The trans will NOT shift down with the TCC locked! In fact, if you stop with the TCC locked in this way it will kill the engine just like stopping a manual trans truck without stepping on the clutch. The Torque Loc device is a way around this. It will maintain the lock until the truck is below something like 30 MPH. Now you can stop without killing the engine.



Ok, so far so good. But remember the trans will not down shift if the TCC is locked. So, for example, if you drop your speed to something like 35 MPH it's still in OD with the TCC locked. Now it you step on it you put a LOT of torque thru the locked TCC with the engine at low RPM so the locking pressure is minimum. This sort of thing reduces the life expectancy of the TCC drastically. In fact, you can just tear it right out this way. If the TCC is manually locked it WILL upshift. There is a real temptation to drag race with the TCC locked because there is no slippage in the TCC and even with a stock VB the shifts are very quick. In fact it bangs from one gear to the next. NOT good for the transmission!



Same thing with towing. The stock TC is so sloppy that if you have a manual lockup switch or a Torque Loc the performance is so much better with the TCC locked that many people leave it locked. This sort of use will eventually tear the TCC out, especially if the engine has been modified to release some more of the available power.



It sounds to me like your TC is starting to exhibit symptoms of a TCC problem caused by your Torque Loc.