I have a 73 firebird, originally 350/350 now a 400/350. Anyway, my wife was
driving to a friends' house and when she started the car up to back out of
the driveway, it just went forward instead. I checked the linkage and
everything appears to move correctly from the outside of the trans. I asked
her is she drove it hard or anything just before this, and she said no. I
checked the transmission fluid level and color. It was full and red. I drove
the car and this is exactly what it is doing.
I put it in park and the wheels lock. If I rev the engine in park, the car
jerks forward. Any gear that I put it in is 2nd gear. It will start in 1st
and shift to 2nd normally. Neutral, Reverse, and Park are all forward gears
I took the shift linkage loose from the transmission, and it turns normally,
and it clicks solidly into each position.
I am totally stumped.....
98 Camaro Z28
Put the shift input shaft on the transmission in Reverse. Start the
car. If it will hold still at throttle, or goes forward you have a stuck
valve in the valve body.
If you have never serviced a valve body before, do not attempt to
learn now. Take the car to a shop (not Ammco or IT), and have them
disassemble the valve body. Clean the lower section in solvent, spray out
the upper section and replace the divider plate. Have them remove the
valves, and check for binding. You should also have the governor checked
out, as well as your vacuum module.
I have had 4 TH350's that had valve body problems show up for no
reason. All were good transmissions. 1 did have a mechanical damage in the
valve body (like it had been dropped during a rebuild). I had to replace
that valve body, the other 3 were fine after a good cleaning.
As for the problem of starting in *any* gear range, that is a
problem in the neutral safety switch, or the wiring for it. If the switch
bolts or screws are lose, it can move with the shifter. Burnt switches
will at times default to start position.
The "S" link from the flange on the shaft:
To the plunger on the valve body might have worn out and broken also. You
might want to have him drop the pan and check that first Charles, before
some shop takes him to the cleaners?
If the 'S' link is worn, broken or binding, the car would have had to
be put in to the second gear shifter quadrant during operation. Which
was not mentioned as the cause of the problem.
Most people have a hard time even changing transmission fluid, let
alone understanding what does what, and what it should look like.
As for a shop taking him to the cleaners, any decent shop will just
fix the problem for standard rates. If he goes in and tells them
what he wants done, and nothing more with out consent, he can't get
I have no problem taking it apart and doing work on the transmission. I
changed the motor on that car myself, have done all the
transmission/brake/engine work on my 73 Corvette, changed transmission in my
old 75 T/A 455 HD (wish I still had that car!) and plenty of other mechanic
As for the starting in any gear...I disassembled the safety linkage when I
took the shift linkage apart. I just have not re-assembled it because I was
unsure as to what had to be done next.
Describe to me this s-linkage that you were talking about and what to look
for, I will give it a try. Also, if I needed to try to clean the valve body
myself, would this be an easy job, or pretty tough. I really don't want to
pull the transmission if I don't have too, my landlord almost evicted me
when I changed the motor!!
What would a shop charge to get that valve body cleaned?
As I stated before, the transmission fluid all looks nice and red, no black
in it, no grime, no metal flakes. My wife tells me she didnt hear any
clunks, and she didnt have to force the shifter.
I appreciate all of your help so far.
Being able to swap a engine does not compare to internal transmission
repairs. Especially if you do not know what your doing. One mistake with a
check ball (small ball bearings), and things can get expensive. I know
people who build transmissions for a living, they would all advise you
NOT to attempt this your self.
Im not sure what people charge for it. I would charge you 4 hours
labor (@ $80 per hour), plus parts.
Your transmission fluid being nice & red does not mean you do not
have a stuck part, or a broken part. It means the transmission clutches
are working, as is the front pump & torque converter. Not all
transmissionpart failures result in debris floating in the fluid, or
in damage to the friction clutches.
As for doing this laying under a car in a apartment complex, that is
not recommended at all. Not only do land lords frown apon it, you do not
want to get any dirt in these parts. You also want them to be cleaned,
with chemicals you should not use with out a proper storage and disposal
Bottom line, take it to a pro, let him find the problem and
correct it, as well as check out other items that wear with age
(accumulator, vacuum module, seals). You will be miles ahead of attempting
to do it your self.
Internial Transmision servicing requires special skills & tools. If you
want to learn buy a few books & junk yard transmissions. Never attempt
to learn on a transmission you have to having working asap.
I agree. NEVER depend on your "show" or "fun" car for personal transportation.
If you do, you can't afford it. You should always have a backup vehicle.
I blew the head gasket in my Cavalier over the summer and the FIRST thing that
came to my mind before I put a wrench to fix it was how I was going to get
around in the meantime. I already had a spare car, as well as a neighbor that
works in NYC who dropped me off at the subway stop, which turns out to be very
convenient to get to work :).
In such case, I took my time doing the repairs and the results were well worth
it. And that's on a commuter car :).
Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director
'80 Carousel Red Turbo T/A, 27k orig.
'79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig
'84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 143k and still going....
Refinish King has got this one right. It is almost certainly the
linkage has come off INSIDE the transmission. The manual valve, under
pressure will move to the "manual low" position. Very unlikely this
would be a "stuck valve" problem as reverse fluid is directly from the
The only other condition that would cause your symptoms would be a
problem with the forward clutch (overheated and welded up). However it
is likely to upshift to second and third woth this condition.
Drop the transmission pan, follow the linkage, and I bet you'll find
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