4 spd ally/4500/8.1

[dmaxx3500]

can i add 5-6th gear to a 2005 8.1 4500 2wd truck that has a 4spd ally

 

[Diesel Tech]

I do not believe you have and Allison in your application. It is most likely a 4L80E. If that is the case then no you cannot add 5th gear within the transmission. You could add an aftermarket overdrive though.

 

[dmaxx3500]

turns out the truck has a 5spd alli, but it has a overdrive lock out that doesen't let the truck to go into 5th gear,i need to get the truck back to start looking at the problem ,but the customer needs it now

 

[samfraser]

turns out the truck has a 5spd alli, but it has a overdrive lock out that doesen't let the truck to go into 5th gear,i need to get the truck back to start looking at the problem ,but the customer needs it now

may be a stupid question but did this customer enable overdrive disable, by holding the tow/haul button for over 3 seconds?? the most simple solution is usually where I start.

 

[dmaxx3500]

thanks i'll try that,i don't have any owners manuals for this truck,

 

[samfraser]

a picture is worth a thousand words...........

 

[Ed HD]

But the OD disable resets when you turn the truck off.

 

[KevinL]

I am about 3 months late but we have a C7500 with a Allison 2000 at work and it had the O/D lockout was a actual switch it wasnt part of the gear lever

 

[Lancerdually]

I'm learning so what is the verdict? Does it reset after you cut the key off?

 

[Ed HD]

If it's a toggle switch, then I'd guess not. You can't reset a toggle w/o physically moving it.