Tranny issues?

[jhell15]

Hey guys, I’m sure this has probably been posted 1000 times on here so I apologize in advance. I’ve been noticing some slipping lately, mainly between 5-6. Not too familiar with Allison’s but from what I’ve read it doesn’t sound like my truck is going into limp mode. Basically what happens is it’ll get into say 5th gear and my RPMs will stall and then after 3-5 seconds it’ll shift (sometimes hard, sometimes normal) and my rpms will rebound to normal. Almost like my rpms are lagging. Also it shifts into/out of park kinda hard. Like I said not too familiar with these issues, could it be a bad torque converter? Or is my transmission likely taking a crap. Truck has 207k on it, stock everything besides cold air intake and exhaust. Thanks in advance

 

[darkness]

When was the last time your filter and fluid were changed?

 

[Josh154]

Running a tuner at all? When I got my first lmm years ago I thought my trans was slipping just like that. Turned out I was losing some massive rail pressure. It would act just like that in the higher gears, rev with no power and shift hard into the next gear randomly

 

[SoCalMike]

How hard are you in the throttle when this happens? Almost sounds like defuel to save the transmission. When is the last time the fuel filter been changed?



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[jhell15]

How hard are you in the throttle when this happens? Almost sounds like defuel to save the transmission. When is the last time the fuel filter been changed?




Transmission fluid and filters (spin on and internal) were changed right around 200k. Fuel filter was changed at about 204k roughly. Not running a tuner and it’s never had one in it. Honestly never ran the truck too hard, just daily driving is when this happens. What’s “defuel to save the transmission” mean? Sorry not familiar with with that.

 

[SoCalMike]

Best way I can describe it is when the transmission senses slip and pulls fuel. Rpms go up slow along with speed and then it will switch gears and act normal. At least that is how it was explained to me a long time ago. From what you described that is what it sounds like.

Someone more knowledgeable please correct me if I am wrong so I do not give out wrong information.

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[jhell15]

Yeah that does sound like what’s going on as far as symptoms go. Any thoughts on what to do next?

 

[torqued2dmax]

Yeah that does sound like what’s going on as far as symptoms go. Any thoughts on what to do next?

How long have you owned the truck and how many mites were on it when you bought it ? Did you give the year of the truck ?

 

[jhell15]

It’s a 2005 and I’ve owned it for about two years. Was a one owner before me. Knew the guy who owned it, he’s a grain farmer, most pulling the truck did was anhydrous tanks every fall. I wanna say the truck had about 190k when I bought it.

 

[torqued2dmax]

Hey guys, I’m sure this has probably been posted 1000 times on here so I apologize in advance. I’ve been noticing some slipping lately, mainly between 5-6. Not too familiar with Allison’s but from what I’ve read it doesn’t sound like my truck is going into limp mode. Basically what happens is it’ll get into say 5th gear and my RPMs will stall and then after 3-5 seconds it’ll shift (sometimes hard, sometimes normal) and my rpms will rebound to normal. Almost like my rpms are lagging. Also it shifts into/out of park kinda hard. Like I said not too familiar with these issues, could it be a bad torque converter? Or is my transmission likely taking a crap. Truck has 207k on it, stock everything besides cold air intake and exhaust. Thanks in advance

What do you mean between 5th and 6th you only have 5 ! You are feeling the converter going from unlocked to locked mode !

 

[jhell15]

Well between 4th and 5th then, I wasn’t counting and like I said I don’t know much about this. Never heard of a converter going into locked mode, what’s the reason for that and what can I do to fix it?

 

[torqued2dmax]

It’s a 2005 and I’ve owned it for about two years. Was a one owner before me. Knew the guy who owned it, he’s a grain farmer, most pulling the truck did was anhydrous tanks every fall. I wanna say the truck had about 190k when I bought it.

The torque converter is a weak link on Allison 5speeds ,if the previous owner was loaded with 15,000 to 20,000 lbs of liquid on a 5,000 lb trailer leaving one field to another jumping on the throttle to get up to speed with that fluid sloshing back and forth as the transmission was trying to shift into 5th over and over every fall for15 years , that is alot harder on a transmission than a strait pool any day ! My converter went out just pulling a 5th wheeler Evan at Limitless said the clutches looked good but the converter was toast , but when you have it apart that is when it is time to do it right ! GOOD LUCK !!!

 

[jhell15]

Yeah that makes sense, thanks for the help!

 

[SoCalMike]

In normal driving and normal throttle converter lock up happens at about 50mph in 5th gear in my truck and at about 60mph 6th gear happens. This is on an 07 lbz. Lock up happens on converters to give a 1:1 ratio between the crankshaft and transmission so it can be more efficient. All automatic transmissions have converters. They all are unlocked for a while so the engine does not stall.

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