350 turbo transmission help needed

[Beck]

My newest project, '70 Camaro, has 350turbo transmission problems. It is leaking fluid from the speedometer output. That part is easy enough to fix with an O-ring I understand. The bigger problem is it keeps leaking for weeks to months. From what I hear that means the torque converter is draining into the transmission. Is that right? If so what is allowing the leak? There is also a leak at the shifter shaft outlet.
Is it time for a complete rebuild or replacement or is this problem repairable without a complete rebuild?
I don't know the history or condition of this transmission. When I bought the car it would only pull itself in 1st gear. It made it onto the trailer. I suspected low fluid level at that time. When I checked the level it was a quart low and I added that. There were other issues with the front end so I started taking it apart without driving it. It is continuing to leak on the garage floor.
The grill, core support, and radiator are off the car so now is the time to pull the motor/trans out for repair.
I have  been going back and forth between a complete motor/trans swap or working with what is there. I thought about a big block but I have ruled that out. I want to drive it and not stop at every fuel station. I have considered the LS1/auto swap but those are a little pricy. There is a LT1/4L60E for sale for $1500, which I am thinking about. The 350 small block in the car sounds healthy and even if I have to do a complete rebuild of the 350 transmission that is the cheapest solution. I even considered swapping the 350 turbo for a used 200 4R that is on craigslist.

Any and all help and thoughts would be appreciated.

[wayne petty]

oh my


speedo leaks are easy to fix.... use a wine cork....  if you cannot find one that fits.. keep buying various brands until you do...


time to examine the speedo drive housing...

unscrew the speedo cable at the back of the transmission...

remove the bolt holding the little plate that holes the speedo cable adaptor in..

there is a TINY seal inside the counter bore that the driven gear shaft rides against... its held in place with a wire ring...

there is a outer Oring also....

i have found that these speedo adaptors wear... they are easily replaced..

i have found the speedo gears wear where they ride in the housing.. allowing oil to drip past...


this is the best web site to more speedo stuff than i have ever seen

http://www.transmissioncenter.net/speedometer_calibration_______va.htm


wait.. it even gets better... they have a speedometer calculator there also...

click the TH350 link at the top.. so you don't get totally lost on speedo

[enjenjo]

There is a seal on the shift shaft too. It can be replaced in the car with  the proper tool   http://www.tooltopia.com/schley-96480.aspx?utm_source=shopzilla&utm_medium=cse&utm_term=SCH96480&utm_campaign=shopzilla_r1

[Carnut]

I always thought 350 turbo trans were just like Harleys, they all leaked.

Mine has always leaked at the fill tube. Replaced the tube and have tried various sealers but to no avail.

Have thought about one of those Lokars flexible tubes but haven't tried it yet.

[Beck]

Wayne, you get an A+ on the speedo leak. I removed it last night and just looked it over closely. The plastic gear shaft is worn where it goes throught the rubber bushing. It appears that the rubber bushing has some wear also. I see the housing and gears are available on the site you linked.
The speedo cable housing is junk also. Someone has put a bandaid fix on it in the past. I can't tell if there was a factory metal elbow on the cable where it exits the transmission or that was part of the bandaid. There was also a hose clamp installed on this sheet metal elbow to attempt to hold things together.

Enjenjo, I haven't got to that part yet.

Thanks for the help.
My intention was to have the motor and trans out last night. That didn't work out. My garage is like 10 lb of crap in a 5 lb bag. I have all the suspension off the front of the car. When I rolled the engine hoist near the car I realized a couple of things. 1-There isn't enough room to roll the hoist back out with the motor and transmission hanging on it.  2-The hoist didn't fit under the car because of the jack stands holding the subframe up.

[Beck]

Is the correct fluid level this high in the transmission when the car is not running? I didn't realize the fluid was up above the top of the pan when the car was not running. I expected I had another internal problem that was allowing the fluid to drain from the converter to raise the level of the fluid in the transmission when it was parked for long periods. I thought this raised fluid level was causing a lot of my problems. The transmission has been leaking on the floor for 2 months. I don't konw what the volume would was, but a couple of signifigant puddles. When I removed the speedometer gear housing last night fluid flowed from the transmission. I would guess about 16 oz came out. Should the level have been this high?

Could my repair be as simple as replacing the speedo gear housing and gear and the seal on the shifter shaft? No rebuild needed?

[wayne petty]

when the engine is NOT running..  the converter will drain back in every transmission..  sometimes slow.. takes weeks.. sometimes days....

why..  the torque converter has half above the opening ...


be sure that AS soon as you start the motor..   that somebody is standing at the passenger side of the car with several quarts of ATF and a transmission funnel..  ready to check the transmission dip stick and bring the transmission fluid to the proper level before any damage can be done by the pump running dry as it fills the converter and the fluid level drops to zero..

most parts stores stock new speedometer cables and casings... there are various lengths and end styles..

this is what shows for the 70 camaro with a automatic
Pioneer/Speedometer Cable
For your 1970 Chevrolet Camaro 5.7L 4BL OHV 8cyl
Part Number: CA-3005
Alternate Part Number: 03101

http://contentinfo.autozone.com/znetcs/product-info/en/US/pnr/CA-3005/image/4/

!!!Shh!!!   its only 11 bucks for the cable at AZ...


for those who do a LOT of junk yarding..   when you see a front wheel drive cad... with a conventional direction motor.. 79 to 85 eldo.. 80 to 85 seville slant back..   the speedometer cable has a short 90 degree bend .. the section is about 8 inches long overall..  has the proper threads to screw to the transmission speedo adaptor and the cable can thread onto the end...  a pair of them could be used to route the speedo cable up and then forward to clear exhaust systems..  i keep forgetting to look at the GM section when i go junk yarding..