transfer case questions...

Wikid 1

Wikid 1

200+ lbs of puppy!
so I've got a whole bravada lined up for 300 bucks, it's a rear hit on the right side just behind the axle, no frame damage still runs and drives, salvage. its also a 93, lots of options and just the transfer case i've been looking for, not to mention front axle and propshaft, now... how would i tell if the VC is burnt out on this thing? the guy says "he doesn't think the 4wd works any more"?!? it's still worth it to buy it if it is, i could part it out for much more than i bought it for, but my main concern is the Transfercase is there any decently simple test i could perform while it's still in the vehicle to check this?
 
J

'JustDreamin'

Dream: 6LV8 Turbo Bravada
Re: transfer case questions...

I've asked this question before. Never gotten a solid answer.

There should be a way to evaluate the transfer case using a torque wrench (might be a really big torque wrench).

However, there are two problems
1.) I haven't seen a writeup of the the exact procedure required. I'd expect you'd need to lock the input shaft (transmission), hold the rear output shaft (leave the driveshaft connected, set the parking brake) and apply torque to the front input shaft. Read what amount of torque it takes to get the viscous to slip.

2.) Which leads us to the next problem. What torque value means the tcase is good? There's got to be a minimum value but what is it? If it slips at 5 ft-lbs, the VC is done by not having enough torque capacity. And if it doesn't slip until 8000 ft-lbs, obviously the VC doesn't slip at all and won't work right either (gives you the 4wd shudder when negotiating in parking lots).


The reason this was last brought up was trying to evaluate used tcases at the junkyard. At that point, most would no longer be in the truck and are much harder to evaluate (have to hold the case, lock 2 shafts, and then apply torque to 1 shaft, tough to do on the ground).

'JustDreamin'
 
Wikid 1

Wikid 1

200+ lbs of puppy!
Re: transfer case questions...

thanks Dreamin, well, locialy using that method I'd imagine somewhere around 350/400 ft/lbs would be a good slip? thinking that if your applying that much tq to the inputshaft, and have the front wheels locked, you may expect the rear to slip by that point, correct? also would you happen to know what a VC would cost? or would it just not be worth it at that point and just get another T case? thanks
 
J

'JustDreamin'

Dream: 6LV8 Turbo Bravada
Re: transfer case questions...

I don't know what a good torque rating is. Might be significantly higher than 400 ft-lbs, really don't know. Either way, its tough to get that kind of torque without a 3/4" torque wrench and a length of pipe.

Pricing I've seen on new VC's is like $600 to $800.

Can you drive it? Here's 2 tests that should help figure out if its any good (assuming the front propshaft and all the front end pieces are still in place).

1.) Drive it in tight circles at low speed on dry pavement. Shouldn't buck or anything silly like that. If it does, the VC is locked solid and needs to be replaced.
2.) Remove the front propshaft and drive the truck (briefly). If the truck doesn't move, the VC won't lock at all and needs to be replaced.

A word of caution: Be careful parking a truck with no front propshaft. If you park on an incline, the truck may actually backdrive the VC (very slowly) so that in several hours its moved from where you parked it (maybe inches, could be many feet). If you've got to park w/o a propshaft, use chocks or the parking brake.

'JustDreamin'
 
Wikid 1

Wikid 1

200+ lbs of puppy!
Re: transfer case questions...

excelent, thanks man! yeah, i've got a 1" tq wrench for doing axles on semi trailers :D she's about 5 ft long and goes up to 550 ft lbs yeah i can drie it, i'll take a look at it this weekend and see how it checks out.
 
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