I just realized by doing a side by side comparison with a friends turbo 400 and my own (both are out of trucks)that mine is a2wd case. There is no K on the casting on mine and has a regular sheet metal converter cover like on a passenger car or 2wd truck. My friends has the K stamp on the housing and has a cast aluminum converter cover that has strut rods that go to the motor mounts. I got this trans years ago from GEAR TECH HEAVY DUTY they used to advertise in the back of Four Wheeler orPetersens 4wor magazine. When I ordered it with my 205 t-case the guy on the phone asked me if I wanted the strut rods that go to the motor mounts to the converter shield ,and I said no cause my motor mounts would not accept them or at least Ithought Ididn't need em. So what did he do , he sent me a 2wd case with a conversion shaft to plug into the 205. I'm finding out 15 years later that it is indeed a2wd case , Iwas supposed to be getting ONE TON CONVERSION PARTS like was in the ad. oh well . My question to you all is : will the two wheel drive case hold up to semi harsh four wheeling or should I not sweat it. One of those REID RACING SUPER HYDRA 400 cases would sure be nice if I could afford it!
CK5
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2wd turbo 400?
- Thread starter 4xfrankie
- Start date
Wait, this tranny has been in your truck 15 years? And you are just now wondering if it will hold up? Sounds to me like if it's been there for 15 years no problems then you should be fine, and if it does break, you got your money's worth. 15 years is a pretty good while on a Tranny.
woops I forgot to mention that after I got the transmission /transfer case that the truck was driven about 400 miles and then torn apart for restoration.sorry should have mentioned that .After looking at the extent of the body rust the body was scrapped, and the rest of the parts were moth balled.Went on to numerous other projects ,and now I am finally assembling all the parts and contemplating a body to make a complete vehicle.What I am concerned about is the case itself cracking cause it isn't supposed to be as thick as a K case.
1) You most likely do not have a "conversion shaft" as the short 2wd shaft is the same as the one used for the figure "8" adapter 205 combo. My last th400 was a 2wd short shaft undrilled "K" case from a V6 Astro van. This trans had the bosses for a thick cover but they were unfinished and it came with a tin cover.
2) "K" cases (some also had "HD") were more of a year model thing that 2wd vs 4wd. GM started phasing these cases in around '78~'79 (in 4wd's mostly) but eventually everything got them.
3) The thicker covers with the motor mount bars are nice insurance but the internal differences are between shallow and deep pan versions rather than "K" vs regular cases.
Ultimately, imo, since you weren't using the motor mount bar set up you simply got the more common standard transmission shell with the correct length tailshaft.
2) "K" cases (some also had "HD") were more of a year model thing that 2wd vs 4wd. GM started phasing these cases in around '78~'79 (in 4wd's mostly) but eventually everything got them.
3) The thicker covers with the motor mount bars are nice insurance but the internal differences are between shallow and deep pan versions rather than "K" vs regular cases.
Ultimately, imo, since you weren't using the motor mount bar set up you simply got the more common standard transmission shell with the correct length tailshaft.
My '82 K2500 has what looks to be a 2wd TH400 in it--and whoever installed it used a typical tin bell housing cover,it had no provision for the "strut bars" so they just left them attached to the motor mount pads,and zip tied them up out of the way..it has a NP208 so they must have swapped the output shaft for a 4x4 length one..
I have plowed a LOT of 2-3 foot deep snows with this truck and so far the only issues I had with the transmission was when the vacuum pump died and it wouldn't upshift right--supposedly it was rebuilt shortly before I got the truck,and it shifts pretty firm,so it might have a shift kit in it..
As far as yours lacking the "K" case and those strut bars--I wouldn't lose much sleep over that..
I have had the rear wheels leap off the ground quite a few times when ramming a snowpile back further--that should have broken the case if it were going too I would think..
Sometimes I wonder if those bars help,or make it more likely to crack the bellhousing,by transfering the strain to one of its weakest spots?..
I see a lot of trucks that dont have those bars and 2wd cases on both TH350's and TH400's,I guess as more 4x4s got scrapped the cores for the K cases started getting scarce,so they use a 2wd or car one instead..
But I can understand if your angry about not getting what you thought you were--if you paid for a K case 4x4 tranny,that is what you should have recieved...
I have plowed a LOT of 2-3 foot deep snows with this truck and so far the only issues I had with the transmission was when the vacuum pump died and it wouldn't upshift right--supposedly it was rebuilt shortly before I got the truck,and it shifts pretty firm,so it might have a shift kit in it..
As far as yours lacking the "K" case and those strut bars--I wouldn't lose much sleep over that..
I have had the rear wheels leap off the ground quite a few times when ramming a snowpile back further--that should have broken the case if it were going too I would think..
Sometimes I wonder if those bars help,or make it more likely to crack the bellhousing,by transfering the strain to one of its weakest spots?..
I see a lot of trucks that dont have those bars and 2wd cases on both TH350's and TH400's,I guess as more 4x4s got scrapped the cores for the K cases started getting scarce,so they use a 2wd or car one instead..
But I can understand if your angry about not getting what you thought you were--if you paid for a K case 4x4 tranny,that is what you should have recieved...
You'll be fine w the 2wd case as long as things are mounted properly
I beat the heck out of the Maiden and didnt have a problem until I improperly mounted a skid plate under the t/c causing undue torque stress on the drivetrain in the wrong direction.
I beat the heck out of the Maiden and didnt have a problem until I improperly mounted a skid plate under the t/c causing undue torque stress on the drivetrain in the wrong direction.
Thanks everyone for your replies! When I had the truck on the road it shifted super firm , the guy said he would install corvette servo's in it ,do you think that is why it shifted so hard?And is a hard shifting transmission a desirable thing?I didn't remember asking why about corvette servo's ,I geuss the whole deal about having corvette parts and all sounded like a performance mod ,so I never questioned it.Do you guys think their is any good reason to use corvette servo's in a 4x4 application? I don't remember any thing about a shift kit being installed.,just on the build sheet it says-HD turbo 400 corvette servo,performance convertor.I don't think GEAR TECH HD is even open any more ,cause Icalled the number ,and the guy just said "hello" and I say is this gear tech , and the dude just hung up on me,oh well.I was going to ask him these qustions.
I haven't heard of putting "Corvette" servos in the THM400, but it is a popular swap into the THM700R4.
If memory serves me correctly it is a popular mod to leave the return spring out of the accumulator piston in the valvebody, that will take the cushion out of the 2-3 shift.
If memory serves me correctly it is a popular mod to leave the return spring out of the accumulator piston in the valvebody, that will take the cushion out of the 2-3 shift.
