Thunk when in 4LO

[FriendSite.com]

For the first time since getting the Tundra a month or two ago, I put it into 4LO, hey it was in a car park and I wanted to ensure everything was ok :-).

Figured out it has to be in neutral to shift from 4HI to 4LO, not a problem, beep beep beep beep beep.

Drove forward, lots of revs, little movement, no problem. Stopped, and felt like a jolt. Stopped again, felt another small jolt forward. Shifted back into 4HI not jolt when stopping, back into 4LO, another small jolt.

I'm also having some bad shifts when starting out, as it felt like first gear would slap into place and the truck when then jolt forwards slightly (usually up a hill), its not the ABS check as this happens after I've been driving, and neither is it definitively reproducible (for good old tech at the garage - not been yet) - any ideas if all of this is normal?

[adazzleman]

Originally Posted by FriendSite.com

For the first time since getting the Tundra a month or two ago, I put it into 4LO, hey it was in a car park and I wanted to ensure everything was ok :-).

Figured out it has to be in neutral to shift from 4HI to 4LO, not a problem, beep beep beep beep beep.

Drove forward, lots of revs, little movement, no problem. Stopped, and felt like a jolt. Stopped again, felt another small jolt forward. Shifted back into 4HI not jolt when stopping, back into 4LO, another small jolt.

I'm also having some bad shifts when starting out, as it felt like first gear would slap into place and the truck when then jolt forwards slightly (usually up a hill), its not the ABS check as this happens after I've been driving, and neither is it definitively reproducible (for good old tech at the garage - not been yet) - any ideas if all of this is normal?

Please tell me this "Car Park" was made out of dirt/mud and not concrete. That could be your issue.

[FriendSite.com]

Yes... I just chatted with a Toyota tech whilst I was there ordering a cargo divider, and he said it was due to 'drivetrain twist'. There's so much energy stored in the drivetrain in 4LO, that if you're not driving it on mud/gravel or turning a corner, then it will thunk. Hey, you got to test these things out before you need them! :-)

[adazzleman]

Originally Posted by FriendSite.com

Yes... I just chatted with a Toyota tech whilst I was there ordering a cargo divider, and he said it was due to 'drivetrain twist'. There's so much energy stored in the drivetrain in 4LO, that if you're not driving it on mud/gravel or turning a corner, then it will thunk. Hey, you got to test these things out before you need them! :-)

I was going to say. It would be very normal if you weren't in some deep dirt or mud. I have heard that clunk sound before....and it is very normal. You should never run it on dry pavement if you want to test it out. You probably already know that though....just reminding though.

[FriendSite.com]

Thanks Ad... actually I didn't know, I'm not a 4 wheel junkie, and don't even profess to know anything about that - hey I'm from England (now living in Canada), the only 4 wheeling we do is down to the school ;-)

Although I was quite pleased the other day, the truck pulled a tree out (clearing for landscaping), the tree was about a foot and a half in diameter, and the truck didn't even hiccup or a strain.. I just need to get a gun rack, some horns on the front and paint my neck red ;-)

Thanks for the advice..

[adazzleman]

Originally Posted by FriendSite.com

Thanks Ad... actually I didn't know, I'm not a 4 wheel junkie, and don't even profess to know anything about that - hey I'm from England (now living in Canada), the only 4 wheeling we do is down to the school ;-)

Although I was quite pleased the other day, the truck pulled a tree out (clearing for landscaping), the tree was about a foot and a half in diameter, and the truck didn't even hiccup or a strain.. I just need to get a gun rack, some horns on the front and paint my neck red ;-)

Thanks for the advice..

It's ok. My dad is from England originally also. I am sure he wouldn't be aware of that either. I grew up most of my life in the states...mostly Texas, Alabama, and now South Carolina. For the record I don't have a gun rack or horns. My neck tends to get read though. I am proud of the South and proud to be called a Southern Man.

Here are some tips, and you can find this if you search the forum. Try to put your truck in 4wd at least once a month to keep everything lubed. Do not put it in 4wd on dry concrete, because this can cause damage to the truck. If you don't use 4wd often, take it down a long strait dirt road, and drive it for a while in 4wd. Try to put it in reverse if you can also. I don't know if that really helps that much, but I have been told that, so I will drive it in reverse in 4wd for a second or two....please be safe....I am not saying drive it for a mile in reverse.

For the record I have only put it in 4wd low one time. I use 4wd quite a bit, but have never needed the 4wd low but one time. You will find out that the truck is a beast, and in most cases can get through most situations in 2wd.

I hope this helps.

[Toxarch]

You can run in 4wd on dry pavement to lube the gears as long as you are driving straight. No turns at all while in 4wd on dry pavement.

[FriendSite.com]

Thanks Tox... much appreciated :-)