I've read about 1000 posts on limping the tranny, but am still cloudy on exactly *when* it limps. Is it normally when you are running in OD? I've read some posts that say 1,2,3 were okay, and others say they were toast.

If I'm running a "sport" tune, are the following good ideas, or just stupid?

- use tow/haul, when I want to romp it from a stoplight
- use tow/haul when I want to pass at highway speeds
- disbale overdrive if I want to romp it at highway speeds

It seem like OD is what I need to worry about most, right or no? I ask because I've been playing with my new "power", but was kinda worried about a highway speed roll on when passing...

I dont think tow haul helps, I limped in a`tow haul shift between 4 and 5.


Yes it is the 4-5 upshift and the 5-4 downshift that most limps occur

I also had one at 70mph in 5th giving too much throttle

It limps when the TCM detects excessive slippage.

This would normally occur during clutch release or engagement during a shift.

While it sounds like it would be the most gentle on the trans, one of the more common limps is when the driver "rolls" into the power in 5th gear on the highway to pass.
Apparently, it's better to simply firewall the throttle and let the ECM/TCM deal with the power.

It limps when the TCM detects excessive slippage.

This would normally occur during clutch release or engagement during a shift.

While it sounds like it would be the most gentle on the trans, one of the more common limps is when the driver "rolls" into the power in 5th gear on the highway to pass.
Apparently, it's better to simply firewall the throttle and let the ECM/TCM deal with the power.

Thats what I was asking about the roll on at highway speeds. Will disableing OD help? Or doesn't it matter?

IMO It does not seem to matter whether you are in overdrive or not. Pedal to the metal is the best approach. Like the previous post said, let the computer worry about it.

Suncoast for me soon!!!

Thats what I was asking about the roll on at highway speeds. Will disableing OD help? Or doesn't it matter?

Main line pressure drops with converter lock in fifth.Thus the clutches will have less holding capacity at higher
torque settings on your box,applied in OD.

There's no quick cheap easy way around it.

The term "limp" is also bandied about pretty liberally. There is definitely the base problem of limping the trans after slippage with the addition of too much power and its indiscriminent use (probably about 95% of the reported limps). However, the Allison has protective limiting actions that can and do occur on a *bunch* of problem codes other than just slip. The trans has what is called "failed to range hydraulic defauts" "if the shift selector is moved to forward range, transmission will shift to NEUTRAL, 3rd or 5th range, if shift selector is moved to NEUTRAL, transmission will shift to NEUTRAL, if shift selector is moved to REVERSE, transmission will shift to NEUTRAL or REVERSE. The trans can default to the failed range hydraulic defauts for many many faults, including low voltage to TCM (9 volts for 6 seconds) or high voltage to the TCM (18 volts for 6 seconds).

The term "limp" is also bandied about pretty liberally. There is definitely the base problem of limping the trans after slippage with the addition of too much power and its indiscriminent use (probably about 95% of the reported limps). However, the Allison has protective limiting actions that can and do occur on a *bunch* of problem codes other than just slip. The trans has what is called "failed to range hydraulic defauts" "if the shift selector is moved to forward range, transmission will shift to NEUTRAL, 3rd or 5th range, if shift selector is moved to NEUTRAL, transmission will shift to NEUTRAL, if shift selector is moved to REVERSE, transmission will shift to NEUTRAL or REVERSE. The trans can default to the failed range hydraulic defauts for many many faults, including low voltage to TCM (9 volts for 6 seconds) or high voltage to the TCM (18 volts for 6 seconds).

It is much easier to just refer to all of them as limps. I even got Brayden to agree to that and that aint easy.:D

Is it possible that the trans could be slipping without going into limp mode? Like for example a few short WOT runs with a performance tune. Over time could this cause further problems. Thanks for any imput.

Kyle

Anyone?

Is it possible that the trans could be slipping without going into limp mode? Like for example a few short WOT runs with a performance tune. Over time could this cause further problems. Thanks for any imput.

Kyle

Not really, I don't have the manual handy, but I believe the "trip" for limp on slippage is 100 rpm difference for more than 3 seconds with TC locked. That's not a lot of allowed slippage.

Now, the clutches are slipping/wearing on every engagement/disengagement while the TC is unlocked and that won't throw a limp - but that wear and tear is supposedly engineered into the system.

I believe that limp occurs when the TC is locked and you are engaged in gear and the TCM registers 5% slip. I limped mine on the freeway a week ago in fith gear WOT.

Bentley

I just had Mike put in the Transgo valve kit (along with a flush and switch to TorqueDrive).
I'd agree with Mike and strongly suggest that anyone running power (or even stock, especially on the LBZ) have this done.

I believe that limp occurs when the TC is locked and you are engaged in gear and the TCM registers 5% slip. I limped mine on the freeway a week ago in fith gear WOT.

Bentley

Just rechecked the manual. There is no DTC based on % slip. The limping DTCs are 100 rpm range slip for 2 seconds. They will also throw on 250 rpm TC slip for 2 seconds.

Just rechecked the manual. There is no DTC based on % slip. The limping DTCs are 100 rpm range slip for 2 seconds. They will also throw on 250 rpm TC slip for 2 seconds.

I was just saying what I had read, thank you for correcting me.

Bentley

Meant as information, not correction, Bentley. There are a *lot* of limp DTCs! 100 rpm clutch slip or 250 rpm locked TC slip will limp you in every gear including reverse! I was sure of the 100 rpm, I wasn't sure of the time.

Meant as information, not correction, Bentley. There are a *lot* of limp DTCs! 100 rpm clutch slip or 250 rpm locked TC slip will limp you in every gear including reverse! I was sure of the 100 rpm, I wasn't sure of the time.

No worries and Thank You.

I found the P0735 limp DTC...........at about 90 mph :eek: , scarry when it grabs third gear!

Bentley