i have rebuilt th350 trans in my 50 chev with 327. the car will go forward in gear but no reverse. we cannot roll the car back either. the drive shaft spins only one way and locks up if you go the other way. is there anything i may have installed incorrectly to cause this? its my first th350 build so i am lost and open to suggestions
What is wrong with a 350 when it freewheels in second? It pulls in all gears and only freewheels when slowing down in second
ok so i took the th350 back out. i pulled it apart and checked the sprag. it is turning clockwise and locks counter at this time. that is looking straight down into trans. is that installed correctly? i did not disassemble the sprag but do not know if it was correct when i got it from what i read it is very hard to install backwards, i have not taken it apart to verify does any one have a link to a powerflow chart or something? thanks in advance
The trouble shooting chart offers the following options: Low oil pressure-check with oil pressure gauge for abnormally low oil pressure intermediate servo malfunction-remove pan and valvebody, check for stuck or cocked servo piston, damaged piston bore or seal rings faulty 2-3 accumulator on 350, 350C and 375-check for damaged or worn 2-3 accumulator seal rings intermediate band malfunction-remove transmission,check for band seating, band wear or broken welds on band
I think the pic is for the 'forward' sprag at the front of the trans i am asking about the sprag at the center of the trans, at the center support which attaches to the output shaft. when the rear of the trans is assembled and i try to spin the output shaft, it will lock up on the sprag. will turn freely forward but will lock the output shaft if i try to spin it the other way. i can not even push my car in reverse. is that normal? shouldnt the output shaft spin in either direction when trans not engaged?
The inner race of the center sprag should turn clock wise. Once you have that installed can you turn your output shaft both direction?
I can't come up with a good picture right now! It would indicate that the low reverse roller clutch or the Intermediate roller clutch are installed upside down, but that would be very hard to do. if you look at the low roller jpg its outer contour should fit the ramp of the reverse clutch support (TH350lowsupportcasesaver.jpg) on the outside and the intermediate roller clutch (TH350directdrumsprag.jpg)should follow the same contour of the ramp except it would be on the ID not OD like the low roller. By the way a 350 uses roller clutches and not sprags there is a difference; I borrowed these pictures from a web site and did not re label the TH350directdrumsprag.jpg You will not be able to turn the output shaft in one direction by hand but can with a channel lock pliers.
The center hub of the low/reverse one-way roller clutch, will spin CW but not counterCW With the one way sprag and sungear installed, the output shaft only spins CW.
When i get home i will need to pull apart the one-way clutch and insp the direction of the ramps. both the intermediate and low/reverse one-way rollers, spin in CW direction only?
As saltflats also indicated check your clutch clearances; as a rule of thumb when I used to rebuild for a living I would give .005 to .008" per friction plate so 5 plates .025 to .040 "thousands" I would rather be toward the .040". On the low reverse piston with the valve body out there was a hole in which you could see the piston I would mark this with a scribe and then apply air and then scribe again and look for the clearance. Regarding the roller clutches the springs will be at the top of the ramp and the rollers at the bottom of the ramp.
i took the roller clutch apart and it appears to be installed correctly. inspecting my trans, i noticed that the case saver (anticlunk spring) was rubbing on the drum in front of it. the case saver does not sit down all the way either. it is partially sitting on the snap ring holding intermediate plate to case, is that normal? prob not
Not sure I under stand cant think of a drum close to that spring. Did you buy a case saver center support?
sorry i mean the sun gear bell, is that what its called? the bell between both sun gears.. i didnt buy the case saver, that is what was already in it. i am rebuilding this trans for the first time. i was told trans was bad from PO but he did not know what it needed. the trans has been worked on before, not by me. i do not know who built it last but i was not sure of the work performed. some clutches were installed friction to friction metal to metal, governer gear broken, upshift cable broken and not connected at v-body, etc. etc,, so now i am trying to build a 350, never having worked on one, and parts may be missing and or installed improperly before, and i have no experience nor another trans to compare this one to. i have rebuilt many trans at work at a dealership but no 350.
If you have not been in one before you may be better off to find one that has not been fucked with. Makes the learning curve much easier. If you got an O/H kit you can reuse those parts.
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