Have any of you guys added an extra crossmember to the transfer case to take some load off the trans on 70s chevy trucks? In my 78 blazer with 700r4 and 208 it looks like the stock crossmember and trans mount isn't enough to suppurt all the wieght of the t case hanging off the end of the trans and with the abusive off road use i give the truck i don't want to have any case cracking issues so it it something neccessay for pounding through the sand dunes at 50+ mph? also the cover under the tourque convertoer, is that also to help the trans support weight, my trans dosn't have any cover and you guy have said that i should have thick cast iron cover or something like that  

the thick cast alumuninum cover adds strength to the bell housing, it is held on with six 10mm bolts with 15mm heads, ya definately want to get one put on.
as for the crossmember the key there is the mount. it just needs to have a good mount to absorb the shock otherwise the housing, adaptor or the t-case can be dammaged. about the only way the crossmember will not hold up is if ya get it hooked on something while going 60mph.
the stock crossmember had short brackets that also connected the underside of the top frame rail for added strength and twisting to the main member that sits on top of the bottom rail.  

I don't think I've ever seen anybody add another crossmember, but thats not to say that you couldn't. Like Mud said though, be sure the mount is good, it needs to flex or it's just going to rip stuff up even faster...  

I think the focus is wrong here. The cross member does little more than carry the weight of rear or tranny and Tcase. The twisting counter torque forces are arrested in engine motor mounts not in cross member. I am know as a bit of a advocate for proper axle gears and there is a reason for this. Not only because it improves performance and extends transmission life but also because it reduces counter torque strain on chassis. Those of you out there think that 3.73 and 4.10 are great gears with 35's and 38's and figure the solution is deeper low ranges do not remotely consider the increased average counter torque twist placed on chassis as drive train strains to haul a tall effective final ratio. Every bit of torque applied to turn drive shaft is applied in opposite direction in counter torque (Newton's Law) to be controlled by chassis cross members and motor mounts. Deeper AXLE gears require less driveshaft torque for same ground effort and therefore less counter torque strain to arrest too.  

okay cool, so as long as i get that cover put in and keep a good mount in there i should be fine?  I took the truck to ammco trans to get estimate on tourque converter lock up kit and they were making me feel like i had commited a crime for putting in a 700r4 saying that it was going to crack becuae it was such a bad tranny and with the weight of t case on it it was doomed and yada yada, these guys really seemed to hate the 700r4 oh and snoman i was just woundering if the stock crossmember was sufficent to support tranny and t case not so much about gearing and yes i am getting the axles regeared to 4:88  

last time I checked the 208 wasn't a big heavy t-case. because of where the mount/crossmember is theres no heavy load hanging off of the tranny.
some 700's are a real pain to make shift correctly,(one reason I put trans-go shift kits in em), people tow with em in OD, and they have to stand behind em. thats where the bad rap is from.  

once ya get it regeared you won't need to worry about burning it up unless ya use it for towing, 4.88 sticks ya about 2600 @ 55mph (35" rubber) in third,.... part of the reason gm put the od in properly geared 1-1 ratios, they were not intended for towing in 4th which is about 1800rpm @ 55 in your case... keep er out of OD under a load.

even for 70 mph 4xin on whoops,dunes or whatever I'd shoot more in the 35's/5.38 gear range to get the full potential out of the 700 and still use it for a 65mph daily driver... even at 2200 rpm it will search for gears under a load from a hill or soft ground unless your feathering the throttle.  

I am not so sure I agree with you on how it will pull OD with 4.88 and 35's. My 89 4x4 burb with 3.73 and stock tires does about 1950 at 65 MPH and it pulls OD really well even on highway grades using A/C and loaded with bodies. It very rarely ever downshifts. His combo with 4.88's should make about 2150 at same speed and unless tires are being run low on air or engine is really weak it should make up for extra drag and cruise pretty good.  

yea 5:13 sounds kinda deep for only 35 inc tires and i do about 70 on the highway not 55 or 65 so i think 4:88s are perfect know the question is what locker to put in rear 14 bolt, arb and e lockers are too expensive, 4 wheel parts says ox lockers arn't made for my 14 bolt and a detroit locker sounds like its breaking when turning im told, ive never heard it before, how bad is the detroit noise and should i go instead to a limited slip      

the 89 is gonna pull a little better at the low rpm than the carbureted 350 does..
thats my experience with em, I started building em about 1985 and have fried a countless number of em in my own rigs from towing.... "properly geared", stock and three of em in two weeks running 4.56's and 36's on my full size chevy 6.2/ATS turbo diesel, theres very little flat ground in my local..
if it starts searching, get it out of OD...
I love the 700's but they don't belong in anything thats heavy or gonna be lugging more than 8,000gvw unless yer gonna babysit it.

I have a detroit, other than the slop it has it's great and I've never noticed a bunch of noise.  

I saw,way back in the day,someone put a double set of crossmembers in their chevy,look in the back issue collectionof either here or fw&or,its from the late 80's i think,its been done and i dont see why it cant be done again,ya see a problem,ya fixit,besides,they make for a nifty place to mount that big ole skidplate youve always wanted! i wonder if a big enough skid plate will ever be made for a k10 style chebbie??
who knoes,ya may start a trend in your town!
oru or some one like that may give ya some ideas  

that was cause the guy also had a divorced 205 t-case running off of the 454 and 700r4-208, to power the tandem 10.5 14 bolt axles.

it was in the peterson's 4x4 mag in the late 80's as I recall, I might be able to find it even!  

mudb8-.:
the 89 is gonna pull a little better at the low rpm than the carbureted 350 does..
thats my experience with em, I started building em about 1985 and have fried a countless number of em in my own rigs from towing.... "properly geared", stock and three of em in two weeks running 4.56's and 36's on my full size chevy 6.2/ATS turbo diesel, theres very little flat ground in my local..
if it starts searching, get it out of OD...
I love the 700's but they don't belong in anything thats heavy or gonna be lugging more than 8,000gvw unless yer gonna babysit it.

I have a detroit, other than the slop it has it's great and I've never noticed a bunch of noise.

I have been building on and off since about 1970. Carbed engine can have good low end torque, especially smog motor as they tend to have mild cams and smaller ports which boost lower RPM response. If cam and intake and carb is stock it should do okay. I would run about 6 to 8 degrees before TDC and 89 octane fuel in it and it should help it some. (power and MPG) TBI motors had a head design that swirled mixture that added response but also hurt top end.  

speaking about the detroit, what slop are you talking about, do u think the detroit would be a good choce for this rig, about 50 % street and 50% off road?  

it's a good strong unit, they just have some slop, they tend to turn over a 1/4 turn sometimes before they engage, some people think the rear is bad when they notice it.  

Geo450racer:
speaking about the detroit, what slop are you talking about, do u think the detroit would be a good choce for this rig, about 50 % street and 50% off road?

Detroit's like other replacement locker has a issue that many do not realize when they consider them. They have no ability to power both wheels at differing speed in a turn. It is either both tire same speed or 1wd with one wheel racheting in a turn under little or no power. This can make them a heart attack on slick pavement or even a slick hillside. They are also a poor choice if you are plan to tow because they will tend to stay locked and 4x4 will fight trailer and lock axle wanting to go straight in turn.