Official Crawlbox BS thread!

Good idea with the switch!

 

4.3 second case for the 11.7 total is on my order, shipping just after New Years

 

Excited to join the turtle races!

 

Good they brought it back, that was the one that I wanted too.

 

What will your final ratio be with 11.7?

 

160:1, with 4.88 diff.

 

That can't be can it with 11.7.....

 

2.8 low on the A340F
2.8x11.7x4.88=160

 

You are right, idk what I was thinking

 

Need to factor in the first gear too. Mine is 4.71x2.57x4.7.4.56 =259:1

 

thats all you get even with the torque converter locked up?

 

Based on what I can find, yes. The A340 is bombproof but leaves a lot to be desired in its ratios.

 

Torque converter slip in non-lockup effectively doubles the mechanical gear ratio though. So think of it as 5.6x11.7x4.88 on an a340

 

Interesting, thank for the info. Can you expand upon on this, under what scenarios is it locked/unlocked? My understanding of torque converters is very limited, I thought it was locked when you actually put it in gear (L, 2, 3) but my goggling is telling me otherwise and it only happens when in D.

 

You can play around on Grimmjeeper.com for different specs.



Pretty much identical to what tacoboxess get you down plus gaining the strength and front dig with the Atlas.

 

Don't take this as gospel since I haven't had an A340F truck for a while but I remember the shift logic being non-lockup no matter what in first and second gear. Third (OD off button) and fourth (D) are definitely lockup gears though. Lockup occurs at certain speeds and throttle positions that I can't remember anymore.

For crawling purposes, you're always unlocked and taking advantage of the additional slip in the torque converter. Think of a torque converter in non-lockup as a fluid coupling from engine output to trans input. There are two sets of blades that are pitched to have drag in the fluid that transmit power and multiply torque. Typically this is in the 2-1 range.

 

That makes sense, thanks!

 

@rctoy got any pics of how your Atlas is mounted? A mount to the case itself or just the tranny supported?

My current plan is @Bonzen poly motor mounts, chopping the tranny crossmember off and making a new one with derlin bushings at the frame and poly bushings to the tranny, then still deciding on if the Atlas needs a mount. Talked with Advance on Friday and they said it wasn't necessary but I'm not convinced. I do believe that improper mounting, particularly with a tail cone mount like this TMR one, can cause issues if one mount/crossmember bends/moves. Any other ideas?

https://www.tmrcustoms.com/collecti...ducts/atlas-transfer-case-support-ring-flange