Diesel Place banner

1 - 20 of 72 Posts

·
Registered
Joined
·
10,556 Posts
Discussion Starter #1 (Edited)
Had a member ask me this recently and I couldn't remember. Has anyone had an overheating LLY 6 speed?

On Edit;
Sorry, 2nd generation 6 speed manual.
 

·
Registered
Joined
·
840 Posts
Im interested in knowing as well.The 06 tranny cooler is appx 25% bigger by my comparitave measurements and sits in lower section of frontal area.Checked with buddy at Chevy dealer and can get 06 tranny cooler and the two appropriately bent lines for changeover for $150 my price, regularly appx $200.Bolt holes already there to mount it so swap should be very easy.
 

·
Registered
Joined
·
130 Posts
I posted this question in the long overheat thread, and no one ever responded. I wonder if any 6 speeds have had the overheating issue??? Mine seems fine so far.
 

·
Registered
Joined
·
300 Posts
For what its worth, my ZF/LLY has never overheated towing 10-11k.

Chris
 

·
Registered
Joined
·
671 Posts
If I am not mistaken, isn't the ZF6 manual Transmission Engine detuned to 300hp and 530lb torque?? If true, there is a difference in the total setup and they may not be subject to the same issues allison users are having. Correct me if I am wrong here.

John
 

·
Registered
Joined
·
258 Posts
If I am not mistaken, isn't the ZF6 manual Transmission Engine detuned to 300hp and 530lb torque?? If true, there is a difference in the total setup and they may not be subject to the same issues allison users are having. Correct me if I am wrong here.

John
Correct its a 300hp, 520 ft lb version of the LLY, but alot 6 speeders also chip or program to higher levels and still i have heard no issues of overheating. I would think that it would have come up in the lengthy overheating discussion if there was. so it appears that 6-speeds do not have the overheating issue.
 

·
Registered
Joined
·
681 Posts
Most likely not as there is no large amount of heat dumped into the cooling air stream by the manual trans. as with the auto. The cooling system is still the same, so it has extra capacity.
 

·
Registered
Joined
·
5,130 Posts
They often get 4.10 gears as well, right? Engine works less to do the same thing, plus the tranny itself eats less power leaving more for the tires to use......

Biggest thing is the lack of numbers of ZF's, to have enough meeting the max conditions. But they do hold the advantage of no rad tranny cooler and no cooler in front of the stack so those attributes will help them.

.
 

·
Registered
Joined
·
1,573 Posts
Wait there was :
It was something about the oil cooler having a restriction .

:iamwithst

Not a manual .
 

·
Registered
Joined
·
94 Posts
This reminds of something I wanted to ask awhile ago.

Do the 4500's with LLY's have overheat issues?

I have a buddy with a Topkick LLY/Ally and was towing a #16k very tall enclosed trailer thru the desert at very high outside temps (over 100deg) and all I had to watch was the EGT the engine temp stayed normal. I was towing some pretty big hills. I have towed smaller loads on the same hills, same temp with my 3500 and overheated everytime.

Whats the diff between the two trucks as far as motor/trans are concerned?


Mike
 

·
Registered
Joined
·
258 Posts
What are the internal allison ratios versus the ZF?

.

Allison, ZF
1st -, 5.79
2nd (1st allison) 3.10, 3.30
3rd (2nd allison) 1.81, 2.10
4th (3rd allison) 1.41, 1.31
5th (4th allison) 1.00, 1.00
6th (5th allison) 0.71, 0.72
(6th allison) 0.61, -
R 4.49 5.23


Edit: Format didnt workout once it was posted, Allison left, ZF right, i think you'll get it
 

·
Registered
Joined
·
5,130 Posts
So the ZF enjoys superior gearing which equals less engine load. The letup for shifts help the cooling system as well, temps drop instantly when you let off the load even for a second.

.
 

·
Registered
Joined
·
258 Posts
So the ZF enjoys superior gearing which equals less engine load. The letup for shifts help the cooling system as well, temps drop instantly when you let off the load even for a second.

.
True but remember hauling up a long hill is usually done in one gear (no letup). Also we have the ability to lug the engine which i would think would build more heat (example I can haul a hill at WOT 1600 RPM, whcih is torque peak, whereas an allison will downshift).

I think the main two reasons there arent overheating issues in a ZF LLY are that there is no tranny cooler throwing heat into the front stack and that different tuning brings the LLY to LB7 stock hp #'s. I'm thinking that even adding to this factory tuning with say a box is different than adding to the higher rated LLY. Example: a ZF LLY with an edge box level 5 runs different (maybe cooler?) than a Allison LLY with edge on lvl 5 (or even maybe level 4 or 3 to make the HP between the two equal). Different gearing and letup on shifts may have a very minor effect.
 

·
Banned
Joined
·
6,540 Posts
If there is no cooler in the rad, that would be a large burden heat load removed from the coolant. just as the factory engine oil cooler is a positive burden to coolant temp control. A bit more airflow w/o the external cooler

But the ZF is cooled, yes?

IMO, gearing has nothing to contribute in my oh pinion .

The shear scarcity of ZF's make this question impossible to answer, IMO
 

·
Registered
Joined
·
258 Posts
If there is no cooler in the rad, that would be a large burden heat load removed from the coolant. just as the factory oil cooler is a positive burden to coolant temp control. But the ZF is cooled, yes?

IMO, gearing has nothing to contribute in my oh pinion .

The shear scarcity of ZF's make this question impossible to answer, IMO
HEY! There's more of us than you think):h

Nope no cooler on a GM ZF-6. There is on a Ford ZF-6 however (same trans).
 
1 - 20 of 72 Posts
Top