im building a 14bolt FF for my 90 K5 and going with 4.56 gears instead of the 3.73s that it has now. gonna take the front driveshaft out until i put manual hubs on the front axle. my question is, can i run 4WD on the beach (loose sand) with 3.73 front and 4.56 rear (same size tires) without blowing up the tcase?

the 14bolt goes in saturday, and i wanna take it to the beach, but will have to wait to re-gear the front.

thanks,
VirginiaK5  

I would not recamend it,as your front tires would turn slower you would be pushing your frontend and it would not be good for the t-case either.  

gillby:
I would not recamend it,as your front tires would turn slower you would be pushing your frontend and it would not be good for the t-case either.

Actually you have it backwards, the front tires would be turning faster than rear and the front would be trying to drag rear around. It would cause severe drive line bind and I would not try it on a dare and it will likely do worse in sand too than in 2wd.If you have to do it, put front tires on that are 20% smaller than rear and it "should" work. BTW, you do not need to remove front drive shaft, you just need to not use 4wd.  

I run different gear ratios.
But not by much. Off road one needs to MATCH gears. The transfer case would not last 3 feet with gears that are more than say 1% different.

My gear ratios are 4.11 in front and 4.10 in back. I can "feel" the difference in the 2 when in 4lo(I have a 4to1 so it is amplified a bit too). It is kind of like the front has a brake drag a small amount. The front is a Dana super 30 and the back is a ford 8.8 on a Jeep Yj.

Don't engage 4 wheel drive. Unless you have matching gears.  

jeepster1993:
I run different gear ratios.
But not by much. Off road one needs to MATCH gears. The transfer case would not last 3 feet with gears that are more than say 1% different.

My gear ratios are 4.11 in front and 4.10 in back. I can "feel" the difference in the 2 when in 4lo(I have a 4to1 so it is amplified a bit too). It is kind of like the front has a brake drag a small amount. The front is a Dana super 30 and the back is a ford 8.8 on a Jeep Yj.

Don't engage 4 wheel drive. Unless you have matching gears.

4.10 and 4.11 is not really different. I can remember 4x4 trucks coming with 4.09 front and 4.10 rear drive axles for many years long ago. Actually the "wisdom" then was that you wanted front axle to be a tiny bit faster the rear axle to keep it "ahead" or rear axle on surfaces with good traction as it would drive and handle better. BTW, you are going to drag with conventional 4x4 drive even with axles of perfect match because tires will not have the same rolling radius front to rear due to inflation and load on them so there will always be some bind. Back in 70's full time 4x4 was popular because they never was any bind in 4x4 drive when Tcase diff was not locked. I still have a old Jeep J20 with Quadratrac full rime 4x4 drive in it and I prefer it to conventional 4x4 drive for a work truck and offroad usage. The only penalty with it is a bit more fuel usage but they do drive and handle well and there was very few times that I ever need to lock out Tcase diff. If I was building a new hard core off road rig it would have a full time Tcase in it for sure.  

even though it had auto 4x4 (NP231C tcase) i wont need to pull the dirveshaft?  

sorry, HAS auto 4x4  

pull fuse for it  

I would imagine the 90 full size has a 241 t-case...either way you don't need to pull the shaft....just don't pull it into 4wd the auto hubs won't lock in witout power to the shaft. the 231c is a s-10...  

I ran a Dodge Diesel with 4.56:1 gears up front and 3.73:1 gearing out back once on dirt, I had no issues. The drivetrain can handle a lot of abuse in this scenero as long as the tires have low traction. I think as long as you don't run it on the hard pack you will be fine for one trip. I would regurarly shift it into 2wd to un bind things for different surfaces.  

Stover:
I ran a Dodge Diesel with 4.56:1 gears up front and 3.73:1 gearing out back once on dirt, I had no issues. The drivetrain can handle a lot of abuse in this scenero as long as the tires have low traction. I think as long as you don't run it on the hard pack you will be fine for one trip. I would regurarly shift it into 2wd to un bind things for different surfaces.

This is one of the sillier things I had heard. "I had no" issues and "drive train can handle a lot of abuse" First you had issue whether you own them or nor because you were is a CONSTANT state of wheel slippage with ground front to rear (it may have traded axles but at least one was ALWAYS slipping) which would effect stability and control a lot. (kinda like driving with rear axle and front brakes applied) They there is drive line strain on shafts and Tcase from this. To even remotely suggest this is acceptable is very misleading.  

no, its a NP231 C. the 241 was for the IFS, driveside, trucks/suvs.

i dont have autotrac (came out in 99), i have that auto hub bs. i frazed that wrong.

thanks for all the replies.  

VirginiaK5:
no, its a NP231 C. the 241 was for the IFS, driveside, trucks/suvs.

i dont have autotrac (came out in 99), i have that auto hub bs. i frazed that wrong.

thanks for all the replies.

No, it is a 241 as it came is a few different designs. My 89 burb (which was old body style thru 91) has a 241. My son has a 87 burb (same body style) and it has a 208. They changed over around 88 it seems. I was mistaken here too in past because I thought my 89 had a 208 too (they look similar) but it does in fact not. GM never used a 231 in a fullsized truck/SUV. Dodge was fond of 231 and used two versions of it. A LD one with a 3 pinion planetary reduction unit and a "HD" one with a 6 pinion reduction unit. (the HD 231 basically used std duty 241 reduction unit)  

my bad, its a 241, i was confusing it with my 90 K1500 (IFS) silverado, which was a 231.

whoops!  

You know naming a truck line in 99 after what used to be a trim level on a a P/U (ie Silverado) was one of the dumber things GM did.