Turbo 350 Build

[Tyger13us]

Sup HotRod,, Im really glad i found this great site..

Ive got a yard full of squares,, from 73-86..

I just went through my t350 in my 78 4x4 shorty,, frame up build,, to many thing to list..

the t350 works as expected,, when cold,, but after it warms up? after running down the run a bit and full internal temp?

it shifts really soft,, it dont slip,, at least that i can tell anyway,, but it just dont feel crispy 1-2 2-3 like it does when its cooler like when just just got the motor warmed up and ready to go..

it shifts to soon also,, gotta work on the Governor weights and springs..

it has the red stripe modulator,, gave the screw a half a twist in and raised the shift a lil bit,, but no ware near were it should be.......

down shifts ok also but way to low,, anything over 55mph and nada,, so i have like i said governor work to do..

im not to happy about only having 3 forward gears with 3.73 in the front and back,,dana44 front 12 bolt gm rear,, 3k @ 70mph is,, well im sure ya get my drift,, really wanting to stuff a 700r4 in it if i have to go through the work pulling the t350 down for inspection.....

Its all in front of a np205,, so i need to eat my weaties before i go pull it..

I remember something about about the front plate in front of the valve body,, cant remember the name of it,, might not be perfectly flat/warped and leaking...

Im wondering what ya think about this,, im not set up for the 700r4 YET,, ive got 2 of them,,one is 2x and the other is a 4x, both have been gone through and out of running trucks,,pretty pink fluid.. the 4x is, at least the stamp date says 82.. the 2x is an 85,, that is the one im gonna use for parts for the 4x build,, im figuring it would be more up to date,, both out of diesel trucks....

So? im fingering, if i gotta pull the t350,, i might as well just stuff a 700r4 in it for all the work i gotta do..

but i want to get the t350 up to par till i have all i need to do a transplant..

got any idea's about soft shifts? and no it dont SLIDE to the next gear,, closer to factory shifts,, but when cold it will bark the tires.....

thanks in advance!!

 

[HotRodPC]

Welcome aboard. Without driving it, I'm going to say, add another 1/2 to full turn clockwise to the vac modulator. Then adjust your detent cable a bit tighter. That will correct your problem. It will delay shift a bit, and firm the shift up a bit as it does that.

Yeah, the 700r4 would be better choice if you want to drive it frequently on the freeway. Make sure to do the necessary uipgrades to beef up the 700r4. Also try to find a K case from 88-92. Those are the best cases for the 700r4.

 

[Tyger13us]

hay thanks for the quick reply..

yea,, done all that already,, it didnt really helped with the modulator shift part,, kinda sorta,, i kept turning it in 1/2 t at a time,, got about 2 and a half turns on it now,, any more and i might as well just disconnect the vacuum line..

the cable has always been tight,, motor/trans/transfer case All complete new rebuild by me,, so i know it was done right,,hate doin **** twice...

i went and got a transgo reprogramming kit for it,,kit 350 1&2.. with the separator plate/springs for the VB and the governor springs come with it also,, maybe different weights out of a core i got layin around...

hoping that it will solve the problem,, other wise it works great,,it just shifts way to early and to soft after it warms up in drive.........

i gave it a good test run through the gears and it will pretty much spin all 4 (lockers)

hammering it in first, click to second around 6k and shifts hard,, run it to 5k and click to third and still a good solid shift,, but im doing close to 100 by then......

There aint but 1 freeway in this state and thats I-15 and i never use it,, and a couple 2 lane hiways down here in the south west corner,65-80 when the sheriff aint around, all the rest is dirt when its dry and mud up to the axles when its wet,, but going to Vegas on I-15 really sucks,, if ya aint doing 80+ they will run ya over......

I read in one of your many threads about a 700r4 build video on this site and for the life of me cant find it,, by another user ya mentioned?

im new to 700r4's,, done a few t350's and 400's and im looking for tricks for the 700r4,, got the ATSG book,, but it really dont show much other than stock rebuild info.....

K,, well thanks,, im gonna give this reprograming kit a try and see whats up till i can get this 700r4 ready.........

 

[HotRodPC]

Very strange. On a Th350, you have vac modulator, governor and detent cable that control your shift points and that's it. I am wondering if your governor valve may be stuck in its bore. I've never heard of the OEM springs and weights causing an early soft shifts.

On the Vac modulator, the tighter you make the adjustment by turning it in, you're making the vacuum requirement higher to require a shift, so turning it in, wouldn't be equal to disconnecting the line.

 

[Tyger13us]

( On a Th350, you have vac modulator, governor and detent cable that control your shift points )..

Yea,, agreed,,thats why im leaning towards the govenor isnt calibrated for the gear ratio,, the t350 is out of a 79 stepside 4x with 3.07s front and rear..

now my best thinking is, and that aint sayin much,, would be?, that it would have its shift points on the money for those gears and trans combo,, but for 3.73s it would shift way to early in drive,, lighter springs and weights would allow higher D shift points,,

the modulator kinda sorta controls the pump pressure to the valve body and detent and they need to work together.. i read someplace how to adjust the modulator (the right way) buy hooking up a pressure gauge to the case and checking it for no vacuum " high pressure",,and then test for full vacuum to the modulator, and then adjust,, final tweek,, to obtain max pressure.. And at that point stop,, tuning it in any further wouldnt have much effect,, on shift points....

what gets me is the crispy shifts when its cooler and when it warms up/gets to operating temps the shifts are like mush in drive......

so im again? thinkin its in the valve body someplace,, if it were in the drums or pump it would be mush all the time,, its when it warms up there seems to be a fluid leak someplace between the valve body and case? or in the valve body it self,, worn out valve or a control spring losing it strength or something...

so,, im gonna yank a valve body out of a low mileage core and go through it and replace the one thats in the trans now,, obviously its not right,, and also find a different governor,, maybe its wore out also? i looked everything over really well when it went back together.. and find some lighter weights.......

if its still mushy in D then i know its deeper inside,, maybe a cracked pump ring,, it has mettle rings on the pump......

The older i get i cant remember half the **** i used to "know" and it takes me all day to do the things i used to do all day..

im just bouncing ideas around with ya....

Well, have a good one and thanks...

Jeff

 

[HotRodPC]

OK, so what they mean on the vac modulator, is after so much its not going to make any more change. You'd still need it connected or it would shift way late. You're on the right track though. It just might be a fluid pressure leak around a ring or something of that nature. But, I'd still check that governor. I'm thinking if you can get your shift points to drag out a bit, the pressure may come up. How does it shift if you shift manually controlling your shift points? Does it seem like a firm solid then? If not, then you likely do have a pressure issue.

 

[Tyger13us]

Thats how i have been driving it,, manual shifts,, other wise its a dog,, 1-2-3 before 35..it wont down shift anything over 65.....

going down the road 45-50,, shove the peddle down and it will down shift like it should,, wood it and hold it and on the money everytime upshifts @ 55..not high enough though should be 75 or so..

it shifts like it should manually,, not neck snaping,, but ya can tell it shifted,, firm.. thats driving it like a white man,,, hammering it,, it shifts the same,, firm,, hard enough that its not trying to break something,, but firm,,

when i was a wee lad,, like all hot rodding kids,, it had to bark the tires for 10 ft or i wasnt happy,, broke alot of **** that way too... old time bracket racer.....

now that im old and wiser,, hahahaha,, it needs to shift really firm so that i know it aint slipping,, it will crawl up and over the ass end trunk section of an old olds i have without much effort at all,, so it aint slipping any..

it has 31x10.5x15s cooper stt's,, dont want or need anything bigger with 3.73s,, but it has rough country 4 leaf spring up front for a 4 inch lift (was the 6 leaf spring to start with but it was to high and to damn stiff) and a body lift of 2 inches,, the reason for the body lift is so it aint such a bitch to work on and thats the only reason......

the rear springs i made custom my self,, trial and error to get it level with the front and soft enough to ride really nice even with the rancho shocks on really nasty dirt roads and can still haul 1 ton in the bed without squatting to much......NO BLOCKS..... dead mans bricks.......

i was out scrounging up parts for the back room work bench,, yep im single also YEA!!!! so i can work on my **** inside so i dont freeze to death...

but the wind kicked up, wind chill of about 10 and there is a storm coming from what they say,, sunday-monday,, so im not gonna get much of anything done,, to old to be layin in the snow under a truck working on a tranny with trans fluid runny down to my arm pit,, so when im going to be able to get to it is anyone guess,, but i can bench the valve body and governor and at least get it ready to go in...

 

[texmechs]

turbo 350 low-reverse

Just like to verify something. Looking at the picture of the low-reverse seals, on your turbo 350 build thread, I have some in a kit I bought several years ago that look like yours. They are flat, square on the edges, and quite flexible, and no lip. I couldn't figure out what these were for. I thought they were too flimsy to be piston seals. Just wondering if these are the low-reverse seals.
thanks
texmechs

 

[HotRodPC]

Welcome to GMSB Tex.
By your description, of the squared edges and no lips, that is exactly what they are. Low/Reverse Piston seals. Hang out, we'll teach you all kinds of good ****, and maybe you can teach us a few things.

 

[HotRodPC]

I missed that post Ty. Seems we have a few things in common. I was an illegal street racer in Los Angeles in my younger days. IF it didn't bark tires, it wasn't worth having. I built lots and lots of transmissions just from people watching my truck and they way mine was built. Nothing more exciting that watching other racers too and someone in the audience say, DAMN, did you see that second gear squat and scratch? I need to talk to that guy and find out who built his trans. Then someone points at me and says, that guy right there. He also built the trans in that Red Nova, the Green Chevelle, the 56 Pick up,..... Cool ****. Now we're only talking 12-13 second cars, maybe a few high 11's but nonetheless, they held together. And really cool when your trans holds up but driveshafts and rear ends are being broken. I've broke lots of drivetrain parts in my day.

 

[texmechs]

info

appreciate the info hot rod. was going to run the low-reverse with the old seals, till I read what you said about better to go ahead and reseal it. already had it back in the case, pulled it back out. had checked it with air and was working all right, but the seals were hard and getting brittle. doubt it would have lasted long. so thanks for info. you sure have a nice thread. must have took some time and effort to put this all together. ty was talking about getting older and can't remember much, I'm 65 and spent about 30 years on drilling rigs, wore my body out. I can't remember anything and if i can, can't get my body to do what i need it to do.
Thanks
tex

 

[HotRodPC]

Yep, glad you changed your mind about those seals in the rear of the case. Those are always the first ones to wear out or get hardened cuz of all the heat back there and far from the circulaton of fluid.

You're right, it does take alot of time to put threads like that together. And very slow in building too when you're stopping after every part to take a few pics so you can choose which one to use, then have to cut it up and crop it, along with resize it to fit the forum.. Then all the description. But it's worth in the long run cuz many get use of it, and as you speak of getting old, I am on my way too, and I am sure I'll be reverting back to my threads someday just to recall and job my memory. I hope to do write ups on Th400, 700r4 and 4L60-E also. I'd also like to do one on an SM465.

I guess I just lke helping those who are willing to help themself. Transmissions aren't for everyone to tackle, but I'd hope the thread can show people that and help them decide whether they should attempt it or not, or leave it to someone more experienced, or for those who are mechanical enough to grasp it, then a good guide to help back up their other resources like the ATSG manuals that are very vague and geared for the pros.

 

[Tyger13us]

I missed that post Ty. Seems we have a few things in common. I was an illegal street racer in Los Angeles in my younger days. IF it didn't bark tires, it wasn't worth having. I built lots and lots of transmissions just from people watching my truck and they way mine was built. Nothing more exciting that watching other racers too and someone in the audience say, DAMN, did you see that second gear squat and scratch? I need to talk to that guy and find out who built his trans. Then someone points at me and says, that guy right there. He also built the trans in that Red Nova, the Green Chevelle, the 56 Pick up,..... Cool ****. Now we're only talking 12-13 second cars, maybe a few high 11's but nonetheless, they held together. And really cool when your trans holds up but driveshafts and rear ends are being broken. I've broke lots of drivetrain parts in my day.

yea,, back in the out law street racing daze,, i had a 64 chevy nova 327 .060 over 12:1,, big rods and steel crank 30-30 duntov cam,,2x4bbls t350 5500 stall 3.73's posi out of a 65gto fitted with a torque brace,, lowered fitted disc's up front,, line locked,, it would do 10.90's,, it was a street cruzer,,more of a road race/autocross type car,, drove it all over the country also.. it was well known around the bay area.....

trying to keep a drive line in it was hardest,, i cork screwed one in 3 pieces one time, tacked it @ 8k second gear shift and the center piece came up through the floor and out the roof!!

the front 3rd went round and round and broke the bell housing from the front pan bolt up and over around to the other front pan bolt,, the rear 3rd of the shaft pogo'ed the whole ass end of the car up into the air and snaped off the pinion.. WHAT A RIDE!!

no matter how many drive line loops ya run wouldnt have helped that time,, the trans blanket kept the trans from falling out on the road..

so i got a new case,, put it all back together and the t350 was good as new,, went with a new NHRA approved 1000.00 drive line,, big joints and new ring and pinion and was back on the road withing a week..... after some minor body work,,, hahahahahaha,, the hole in the roof was a B to fix......

way to many street racing stories to tell,, i got a pic of that car someplace,, looked like a sleeper......

 

[HotRodPC]

Hell yeah, sounds like a lot of fun in that car. That's certianly a story of a drag racer. Many times racing, it wasn't a matter of who had the fastest car, it was a matter of whose car would hold together.. I've got lots and lots of drag race stories, from VW Bugs doing wheelies and carrying them almost the full quarter with exception coming down to shift gears and right back up again. Now that was flat ass crazy, to seeing guys trying to LIE and say they wren't sqeezing, yet their fibreglass hood blows right off the damn car and jumps 6 feet in the air thru the hood locks and all cuz they squeezed it to hard off the line. I've also seen a guy blow a motor up cuz his ******* didn't have a full throttle safety switch on his giggly juice button. He or someone had hit the button on the shifter while sitting in the car with the key on to run the stereo. This was sitting in the parking lot where we sat to set up races. Couple guys negotiate a race, so of course we are all gonna follow to go watch. This guy then simply starts his motor. KABOOOM !!! Had NOS sitting in the throat of intake plenum when he started it up. $5000 motor is now junk just for starting it up. Only had about 3 race passes on it, a SBC 400. He wan't very happy. If I had to guess, with inflation, that would be about a $7000-$7500 motor today.

 

[davbell22602]

At the point where the piston, retun springs, retainer and snap ring are back in place. Now we can put in our steels and new clutches that have soaked in trans fluid for at least 20 minutes. These ones happened to have soaked overnight.

So those clutches only in one way this trany or any other trany? Or can the clutches be put in wrong on some tranys.