Going up, no power (1 Viewer)

[fiberboy]

Yes to the drive shaft ? and yes to the Drive plate ?
Got my bird today so I have the rest of the week to climb up and down the damn hill and try to recreate the problem. stay posted

 

[IdahoDoug]

I'm sticking with "didn't know putting it in 2nd on a hill prevents the tranny from downshifting to 1st when it badly needed to".

DougM

 

[7schulz]

I'm sticking with "didn't know putting it in 2nd on a hill prevents the tranny from downshifting to 1st when it badly needed to". DougM

Which sounds like this.

Sounds like you have stalled your engine power/tranny combo, If you know this is going to happen downshift earilyer.

Not enough power for the incline/gear ratio/Torque convert. So when he put it in low he had a better mechanical advantage to move up the incline

Gradeability
The tractive effort available at the wheels must be greater than the sum of the rolling resistance encountered. If this is not so, the transmission must be shifted to a lower gear in order to increase the tractive effort. The percentage of grade which can be negotiated is given by the formula.

G= [(100 x T x R)/(r x GVW)] – RR


Where:
100 = A constant expression percentage grade and inches
T = Motor torque in lb inches
R = Overall gear reduction including both axle and transmission
r = Rolling radius of loaded driving type in inches
GVW = Gross vehicle weight in pounds
RR = Rolling resistance expressed in percentage grade.

Example:
What percentage grade can be negotiated by a vehicle having a hydraulic motor torque of 1000 lb inches, an overall gear reduction in high of 12 to 1, a tyre rolling radius of 15 inches and a gross vehicle weight of 10,000 lbs driving over good concrete?


G = [(100 x 100 x 12)/(15X10,000)[-1.5%

 

[kerrye]

If that's the case, then why did the engine rpm's keep increasing? If the gear was too high, the engine would bog down instead of rev up.

 

[7schulz]

It will rev up to a certain point that is the stall RPM for that grade and gear. B.c he was at a stop it reved to XRPM and stalled there. Not enought HP in 2nd for that grade. If something besides the TC is spinning and power isn't being applied it would rev up to redline(no drag on engine power).

 

[AJLFJ80]

I think we should just stick to the simple answer: 3F-E power.

 

[Grench]

I think we should just stick to the simple answer: 3F-E power.

Not if you actually bother to read the OP's issue.

The claim is that his truck's behavior changes, on pavement, to more usable power, when he pushes the CDL button.

My translation is that if this is so, then under no-CDL conditions, something is slipping in the drive train or the OP is confused on the vehicle operation.

The L2 not allowing 1st gear on 80s isn't a commonly known bit to people new to 80s - so there is a good chance that this is the root issue.

 

[jonheld]

I think we should just stick to the simple answer: 3F-E power.

That's silly. I have never, during 19 years of ownership, failed to climb any hill assuming I have traction. That includes pulling an FJ40 on a dual axle trailer over the Pocono mountains. Yes, I was down into 2nd gear at some points, but she made it up and over. I have been on rediculous hillclimbs in the woods and have NEVER ran out of grunt. This includes running 35" tires with stock gears.

If the transmission is in 2nd then the TC will stall if the hill is steep enough. I've done that many times in low range. That's simply me being careless and knocking the shift lever with my right hand.

 

[7schulz]

Now this is gradability
YouTube - Allison 4700 Transmission equiped Volvo FH 540 pulling 240 ton in a 8% grade

YouTube - Grade Demonstration

 

[7schulz]

[QUOTENot if you actually bother to read the OP's issue.

The claim is that his truck's behavior changes, on pavement, to more usable power, when he pushes the CDL button.

My translation is that if this is so, then under no-CDL conditions, something is slipping in the drive train or the OP is confused on the vehicle operation.

The L2 not allowing 1st gear on 80s isn't a commonly known bit to people new to 80s - so there is a good chance that this is the root issue.
.[/QUOTE]

You can't assume it's the CDL it's more likely b.c he put it in 1st at the same time. No mention of pavement.

 

[Tenzig Norgay]

You just pooched the tranny. Next time try hitting her with speed. I can't find the thread, but someone had a similar experience when going up a steep hill, they came to a dead stop. I would make sure your throttle kick down cable is adjusted properly, check fluid, maybe change it, but I don't think its a big deal. 20 miles an hour, approaching a steep hill,(and they're steep in your parts), thats not a great speed. Stop road hunting and get on the gas, get into the woods and stop lolly gagging and dilly dallying!

 

[fiberboy]

Ok, So here is the final answer you have all been dying for
Climbed the same hill on Sunday twice, first time left it in drive and truck went up fine, no problem, No CDL needed. Second time put it in 1 and again crawled right on up without the CDL engaged. Conclusion is that the original problem was due to the fact I left the transmission in 2. another MUD mystery solved. thanks again to all.

 

[CJF]