Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
10/30/21 1:50 p.m.

Starting to commence to think about 4x4-ing Candy Van.  It's already AWD, so in theory it's just a transfer case and a front driveshaft away from having real 4x4.

So I'm mathing to find out how much torque I can realistically give the 7.2" front diff.  A couple sources say that the diff can take a pinion torque of 2333 ft-lbs.  Since the current viscous AWD box is set for about a 40/60 split and has no low range, I'm sure the 7.2" is adequate.

So:  LM7 5.3L makes 315 torques, but I'm going to round it up to 350 to be safe and because I might do a tune and exhaust some day.

350 torques * 3.06 first gear * 2.78 xfer case low range = 2935 torques on paper.

Divided that by two since it is a 50/50 torque split = 1467 torques.

Where I'm having trouble is the two huge question marks of A) how much a torque converter multiplies torque, and B) the other big question mark of how much torque I'll actually be making.  I won't be crawling over a rock at WOT, so how does one factor in all those unknown variables?

I guess I'm asking... how would an automotive engineer choose components.  They put a 7.2" in the AWD vans, but an 8.5" in the 4x4 trucks with the same basic layout.  Did they do that because the trucks actually need the capacity, or is it just because they've always done it and it was the easy button?

DeadSkunk  (Warren)
DeadSkunk (Warren) UltimaDork
10/30/21 2:01 p.m.

Curtis, why did you stick this in the Challenge sub-forum rather than the Grassroots one?    ,,,,,,,,and I know nothing about torque multiplication through convertors.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
10/30/21 2:27 p.m.

In reply to DeadSkunk (Warren) :

Because I'm obviously an idiot.  Oops.  No idea how I got here.

Stampie
Stampie GRM+ Memberand MegaDork
10/30/21 4:40 p.m.

In reply to Curtis73 (Forum Supporter) :

Still reliving last weekend in your mind?

AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) GRM+ Memberand MegaDork
10/30/21 6:24 p.m.

I don't think the converter multiplies it, it just controls the amount that is transmitted to the input shaft vs engine RPM.

Robbie (Forum Supporter)
Robbie (Forum Supporter) GRM+ Memberand MegaDork
10/31/21 12:20 a.m.

Also a transfer case can probably do 100% of the torque to either shaft.

Like how if you spool a diff then both axles get 100% torque.

You'll need to log in to post.

Our Preferred Partners
Fhe2ffC1sb8aPQr0O0pH26o3HcHmPloahSRVGKUQuD43ao0dp3ZCUguh8SZyyGxB