Transmission question

I bought my truck in March and I am very happy with it, but one thing I've noticed it does sometimes that makes me a little nervous. My driveway is about 50 feet long and somewhat steep, when pulling into my garage I slowly accelerate up hill then when entering my garage I let up on the gas pedal and it's like a little jerk or bump? Kind of hard for me to explain it but maybe almost like a transmission shift when letting up on the gas pedal, although I would expect it in first gear already? Other than this the power train seems to work great.

I've been wondering about this for a while now, so its time to post to this huge knowledge base that's this forum.

 

Do you have any lift or anything? Doesn’t look like it from your profile picture. Does it do it anywhere else? It could be tension in your drivetrain that gets released at the top when you let up on the flat part. Some people say their trucks get a bump like they were rear ended at a red light and the common answer seems to be tension in the drivetrain.

 

Drop it into S-4 and see if it still happens.

 

I'm gathering that your driveway is steep UPWARDS. When pulling into your driveway is your approach direction downhill, then turning into the driveway and changing direction to now go uphill?

 

The truck is stock, SumoSprings installed but that shouldn't make any difference. I haven't noticed anything odd anywhere else, and it could be described as a bump I suppose. I'll try S-4 and see, although it seems if I'm light on the accelerator when entering the garage I don't notice it more so if under a little higher load.

 

That sounds to me like tension in the drivetrain somewhere getting released at the top when you change angle and throttle.

 

I generally enter in the direction that has the street somewhat uphill then my driveway is much steeper uphill witch has me using the accelerator harder till I start to enter the garage then when letting up I'll feel the "bump"?

If I go easy on the entry and have less letup on the pedal I won't even notice anything unusual, just a smooth transition in.

 

Have you tried backing in to see if it makes a difference?

 

Well yes I have backed in on occasion, but generally its a slower process and I haven't noticed anything. I will have to try backing in more abruptly and see what happens.

Thanks for all the input, much appreciated.

 

In my experience this transmission has always felt a bit clunky during low speed maneuvers like that. Just gotten used to it, I guess.

 

Does your Tundra have the factory tow package on it? And the 4.30 axle ratio?

 

Yes to both, and TRD off road package.

 

I have the tow package and 4.30 axle ratio. Commonly when gently approaching, at a slow speed, a slow speed incline (your driveway) the truck will pull it in 2nd gear at first and then as the load increases will dump down into 1st gear ("granny low" to use an old timers term) which could be what you're experiencing.

 

I understand what your saying but this happens when letting off of the gas. I suspect the truck is already in first gear, but maybe I need to try a complete stop at bottom of driveway to make sure its in low gear.

I can relate to the "granny low" being somewhat an old timer myself.

 

I have experienced the same thing when slowly maneuvering sometimes. Never really gave it much thought because I figured it was just the drivetrain adjusting.

 

I want to thank you all for your thoughts, this truly is a great forum with many helpful members.

I have been thinking about this and was just returning from a grocery run. When I stopped at the corner (two houses away from mine) I put the tranny in S-1 then drove up my drive way, upon entering my garage and letting up on the gas there was no jerk or bump felt. Although I need to do more experimenting this has me thinking maybe I've usually been in 2nd gear going up my driveway then when letting up on the gas and tranny shifts to first gear. That would explain the jerk or bump I've been feeling

 

Same thing in my truck. It goes up the driveway in second gear then right before I stop at the top it downshifts to first with an annoying bump. I consider it normal but I don't like it. One of the few things that my old Nissan did better, transmission calibration.

 

This is what it feels like to me exactly.
OP's issue is identical to my experience under same conditions.
Feels like its stuck in 2nd gear and struggles up the driveway until dropping to 1st.
Its annoying as hell.

 

Sounds like a harsh downshift to 1st gear. Allison automatic do the same thing.

 

Mine has been doing the same exact thing. I've been thinking my transmission is going out or something because it only happens on steep inclines. I've actually got appointment in the morning at transmission shop