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Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Transmission - Rearend> Turbo 400 - No reverse/No 3rd
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Topic Review (Newest First)
07-06-2012 07:27 AM
Rattmoses
Tranny

Well, I sure appreciate the information . As it stands now, I have replaced the Turbo 400 with another one. I lucked out and found a guy with a rebuilt for 300 bucks.. couldn't beat that and it operates great. I plan on rebuilding the old one in the future so the link and info. will be used in the future... thanks again.
06-22-2012 11:10 AM
mrtim i had some spare time and finally got around to re-registering on this site and saw your thread here. i will offer you some insight.

the direct drum is what drives your transmission in both 3rd gear and reverse. all automatic transmissions to get gear reduction drive one part of a planetary and hold another part. third gear locks the direct drum to the drive....or forward drum.....causing 1:1 and basically spins the guts of the tranny as a unit. therefore the rear servo has nothing to do with the third gear failure.

the rear servo under the cover is used to actuate the rear band. it not only holds the gearset in reverse but also applies for engine braking in the low 1 position. so if you pull it down to low 1 from drive range and try to kiss the steering wheel......your rear servo and rear band is working.

since you have two problems that use the same driving source, that is more than likely the culperate. starting the car in gear will not damage a direct drum. we do it all the time for my friends who demo derby.

since you have 1-2, it isn't a gearset problem or a forward clutch problem. you simply are not apply'n the direct clutch. if it is a new build it is possible that the steels are jamming the pack preventing apply. if it came out of a truck....especially a snow plow truck......they are prone to bending the stamp steel piston and blowing the clutch pack out the end of it shattering the direct drum backing plate.

here is a link for a great parts referrence to understand more what i am talking about. they also have good prices and products.

https://www.wittrans.com/Schematic.a...ansmission=400

the 2-3 shift valve could be hung up as well, but i don't see that very often. also the center support can be damaged causing problems, but if 2nd gear is still there i would doubt it. an improperly installed shift kit will also do the same things you describe.
06-21-2012 01:22 PM
Rattmoses rick 427,
Thanks again for the infomation. Your help , along with just watching a rebuild video , has boosted my confidence level . I am now an "expert amatuer want-a-be transmission tech". I sold my second home built V-Twin and bought a street rod... trying to recall from things I thought I knew in the 70's. Yes, that's right, you have been trying to help a biker work on a hot rod!
Seriously... thanks for the information.
06-21-2012 12:35 PM
rick 427 The trans has to come apart ....but if you want to verify,you could pull the valve body and seperator plate out ,since the pan is off,and air check the circuits..might be a bit messy with trans fluid up in the trans tho...let it drain for a while after vb is out..rev is the port just next to the servo cover....forward and direct [3rd gear] ports are on either side of the center support bolt....shoot a quick short blast of air into them...a faint but solid thud should be heard when air is put to them....... and flow charts are prob out there on the net somewhere.I allways just referenced my trans shop manuals for them.
06-21-2012 11:52 AM
Rattmoses rick 427. I appreciate your help. So , last night , before reading your response, I pulled the pan and inspected the selector , just to insure that it wasn't simply skipping reverse . After seeing how it is designed I realize that was basically impossible. I was planning on removing and inspecting the rear servo/accumulator this evening, but not sure that is the correct direction now. What would I need to do to verify that the problem is in the 3rd gear drum... tear the tranny down? Also, is there a animation or illustration showing the oil distribution on these things... a flow diagram ? Thanks again for your input.
Rattmoses
06-21-2012 10:26 AM
rick 427 The center support bolt is your 2nd gear apply feed...If loose,will give you a 1-2 slip,or just slide thru till it goes into 3rd in most cases..then the bolt will eventually break,giving you a whole set of new problems............. When you put it in reverse,2 things have to happen for it to back up...the reverse band and the direct [3rd gear] cluthes have to apply.If just the band applies,and not the clutches,or visa-versa,you will feel a slight bump when you put it in R,but no movement. And since you also have no 3rd gear when driving,and the reverse band has nothing to do with 3rd,thats telling me that the problem is in that 3rd gear drum.
06-19-2012 01:18 PM
Rattmoses
Turbo 400 - No reverse/No 3rd

Turbo 400 suddenly does not move in reverse and after pushing it out of the garage for a road test, I discovered it does not shift to 3rd. The transmission was working great until I had accidently started it in reverse one day ( no neutral switch. I have since checked fluid,adjusted linkage,replaced modulator and vacuum line. Yes, I will be installing a neutral switch in the future. Can someone explain to this amatuer what the center case to case bolt is ? As I understand it, it may be lose. Can the rear servo pin length suddenly be out of adjustment? it does seem to me that reverse is holding some pressure , but not enough.

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