On another thread I asked Shifts about my 350 turbo transmission 'freewheeling' in second and he suggested that I check the servo or 2-3 accumulator. I have been working on old Fords for 40 years and I think I can fix anything But I dont do automatic transmissions. Is the servo/2-3 accumulator something that can be checked and repaired without getting serious and taking the transmission out of the car?
I'm going to say yes without looking at my books. The servo is external (IIRC), the accumulator accessible after pan removal. Seriously, get the TH350 book from HP Books, and learn. The TH350 (and indeed moreso the TH400) are two of the easiest automatics to rebuild/build. And you can orient them to more horsepower without buying any "kits", just by some changes on reassembly. I've never gotten any formal training on transmissions, yet I've rebuilt quite a few 350/400 and C4s without any troubles from any of them. One of them even lasted two seasons behind an 11 second big block, and it was a trans I built for street use!! My buddy bought it from me after I built it, and just put it in the car. It wasn't dead, either, he just wanted more. Cosmo
It`s toast! The probability of the servo being bad are slim & none! Clutches are gone, or the lip seal in the drum is blown. Pull it and either rebuild or replace. 200.00 bucks for a rebuild kit & converter, shift kit and be done with it! P.S. After thinking about it you might try checking the govener [ rear of trans, cover on side with 4 bolts ] Pull cover & slide the govener out and look at the gears on it & the output shaft gear, and make sure that there not worn out or the clip that holds the gear to the shaft is not broken and spinning around. This will also cause no shift, or very high/late shift. Have you ever run the car way up, like 40mph and let off the gas to see if it will shift then? If so, it the gov!
Yeah most of the time you can get to it in the car. Flip the ring clip out and pop the cover. You'll probably find a broken spring (I've found several over the years). A quick trip to the pull-a-part and snag another. I keep those around here as well as govenors for those things. You may find that the clutches are already fried but it's worth a try.
Couple things tho Muffman58. There isnt a clutch drum for 2nd gear & the governor cover is just a press in, not bolted. I think you are thinking about a th400. The accumulator is located on the pass side & held in w/ a snap ring. Servo on the other hand is in the case under the valve body. I was told that the upshifts were fine, just no engine braking on coast down.I'd be checking that & or the band. Feel free to call me on my toll free# (877) 737-4438 DAVE P.S. I have videos available to loan if you need one.
Hell, I`m just throwin things out there for him to check. You`re right about the TH400. You know its kinda hard to fix something that you can`t see! My old man had a tranny shop for 35 years and that was my job growing up, but I don`t do too many anymore.
Have to agree intermediate band servo ring leaking or band shot,id run it that way just wont have the second gear engine braking that eats up the direct drum bushings anyway.
Are we talking about a 350 or 250? A 350 does not have an intermediate band. A 250 does. A 250 is the same as a 350 except it has an intermediate band instead of a sprag. The way you can tell them apart is that the 250 will have a band adjustment screw right by the cooler line fittings. Either the intermediate clutches went out or the intermediate sprag is broke.
All my th350s have the band except one took it out and installed transbrake.Mabe i got a few rare th350s with intermediate overrun bands.
Free-wheeling? Does this mean no engine braking ? Lets say it does. The valve body can be pulled to check the servo area and the 2-3 accumilator. GM used a plastic ( phenolic) resin piston there for a few years and they break. The band could be toast , broken , strut broke. The accumilator on the side of the case is the 1-2 unit. It could have eaten up it's self with a broken spring inside. IF the upshifts are fine with the shifter in "D"..... the problem is in the area of the coasting band
I know that all 350's have a band. It is just that they don't have anything to do with second gear. The 250's have 2 bands. The 250's have a band for second gear. Just my two cents.
Some of the posts in this thread and a pm i recieved had me thinking about this. I went to ask my dad. He said that the band that 350's do have, is an aid to the intermediate sprag when in manual second. I am sorry for the not so correct info I posted earlier. Not alot of 350's come around anymore so the memory gets fuzzy at times. Sorry guys.
Lets apply the KISS rule regarding -if you run it up to 35 or 40 and let off the throttle and it upshifts and it could be as simple as a vacum leak in the modulator line. Pull the line off at the modulator and see if it has good vacum or just replace the rubber line at both ends and see what you find while you're at it.
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