Is my transmission going out test

[lethal injection]

I read in diesel performance mag that if you put the emergency brake on and stand on the driving brake and mash it to the floor that the tac should hand about 1500rpms if not the is a good chance the trans is going. I tried this and mine does not hang at 1500 it shoots right on up to about 2500rpms. The truck had 11,000 miles and the juice has never been turned past setting 1. I do not tow very often and when I have its been around 3500lbs. Also if I mash it on a take off I cant even brake the tires loose. I bought the truck used so I dont know how much power I should be feeling as it is new. Should it brake the tires loose?



Thanks for any input.

 

[TEdwards]

I believe our stall speed on a stock transmission is around 2500. so the results you saw were normal for your truck. .

 

[john3976]

I read in diesel performance mag that if you put the emergency brake on and stand on the driving brake and mash it to the floor that the tac should hand about 1500rpms if not the is a good chance the trans is going. I tried this and mine does not hang at 1500 it shoots right on up to about 2500rpms. The truck had 11,000 miles and the juice has never been turned past setting 1. I do not tow very often and when I have its been around 3500lbs. Also if I mash it on a take off I cant even brake the tires loose. I bought the truck used so I dont know how much power I should be feeling as it is new. Should it brake the tires loose?



Thanks for any input.

Why in the world would you want to unleash 610 plus foot pounds of torque on two little rubber motor mounts?



Stop and think for a second, you stand on the brake, the engine is now being forced to twists in its mounts. But hey its you truck if you want to pay for a new radiator and shroud and such then by all means go for it.



Also it is going to depend on what stall speed you converter is set up for. In my humble opinion Diesel Performance Mag just did a big injustice upon their readership.

 

[john3976]

You have a 2005 so you may luck out and not destroy your shroud due to it being mounted on your engine instead of the radiator, but that depends on how far over the motor twists and what it comes into contact with.



I once many years ago replaced a broken motor mount on a Dodge van and when I was done I was going to test the mount by holding the foot break and stand on the go pedal, big mistake, the brand new mount let go and the engine torqued over to the right and took out the fan shroud.

 

[robertyoke]

I would not worry about the motor mounts, what happens when you are starting on a hill with 12k trailer behind you?! If you do that test again just let the trans cool off in neutral before you shut it down, it will make a lot of heat when tested like that.

the 2500 rpm sounds about right for the stock converter.

-robert

 

[BErmoyan]

Our truck wouldn't do a burnout from a brakestand either before we had the transmission built. Some can, and some can't, I really don't know why. Even now, on lvl 5, the truck won't spin its tires if I don't build boost first. I wonder if it should?

 

[cerberusiam]

Mine will only go to 2100 in a power brake scenario. Stall speed is supposed to be 2200 rpm's stock but if you have some mods it will probably go a bit more. The ECU defuels if it does not see speed from the speed sensor.



Not being able to spin the tires is normal also. The ECU will not allow full fuel until the boost is over a certain point. Some trucks seem to allow more fuel than others and get wheel spin from a dead launch and some won't.

 

[john3976]

I would not worry about the motor mounts, what happens when you are starting on a hill with 12k trailer behind you?! If you do that test again just let the trans cool off in neutral before you shut it down, it will make a lot of heat when tested like that.

the 2500 rpm sounds about right for the stock converter.

-robert

Big difference between towing a trailer up a hill, that torque has some place other then just the motor mounts to go, it is being transfered through the drive train, tires, ect.



When you are holding the brakes the torque builds up and there is no where left for it to go except to place all the stress upon the motor mounts.



Like I said it is your truck, if you want to take a chance then go ahead, its your money that has to be spent to fix it.

 

[thejeepdude]

Well in that case, all the motor mounts of every vehicle I have driven should be broken! :-laf



If your motor mount breaks from power-braking, your motor mounts were garbage anyways. I have broken quite a few and never has it been because of this. I have been in many low traction scenarios (offroad) where the tires are spinning and then suddenly get traction and trust me you'll break a u-joint, axle, input shaft, or something else before the engine mount 99% of the time.



Also, do you think that a stock 325/610 floored with the brake on really creates more stress on the motor mounts than a 500/1000 RWHP sledpulling rig does when it starts bouncing? Or the same rig on the strip with slicks? Again, drivetrain <i>usually</i> goes before the mounts.



Not to say you CAN'T break a motor mount that way... let's just say I sure wouldn't want your luck if you do.

 

[JVolpe]

Motor mount and fan shroud would sure be cheaper than any of the other drive train options that would break. Motor mount is the last thing I worry about with 500+ rwhp and 20+psi power brake 4wd launches at the track, that's for sure.

 

[jcroman]

I read in diesel performance mag that if you put the emergency brake on and stand on the driving brake and mash it to the floor that the tac should hand about 1500rpms if not the is a good chance the trans is going. I tried this and mine does not hang at 1500 it shoots right on up to about 2500rpms. The truck had 11,000 miles and the juice has never been turned past setting 1. I do not tow very often and when I have its been around 3500lbs. Also if I mash it on a take off I cant even brake the tires loose. I bought the truck used so I dont know how much power I should be feeling as it is new. Should it brake the tires loose?



Thanks for any input.

that is one of the dumbest tests ive ever heard. all it would even test at all is how well your low clutches are holding and maybe the stator on the tc if you really knew what to look for. Your truck sounds completly normal for a stock tc. I wouldnt sweat it. my truck stock wouldnt break the tires loose and it still doesnt break them loose all that great even with 2 boxes stacked!!!! as for motor mounts it wont hurt them... ... . theres lots of other things in line to break first... .....

 

[JFaulkner]

worrying about motormounts because of a usless test like this is just like worring about your turbo exploding because you didn't wait 2 min to shut it down. STUPID.



Powerbrake away and don't worry about those mounts, worry about the tires.