Auto transmission recommended service

[KirkLazarus]

Long time creeper, first time poster.

 

'70 510 2 door automatic

 

TL;DR - While I have the transmission out of the car, do you recommend any service? Rebuild, filter+flush? 

 

I bought this car in 2010. Ran it for 2-3 years with no real issues. Had to park it in storage as I traveled for work. Finally got it out and have some money to get decent body and paint work done. I have the Transmission, drive shaft, differential, and axles out of the car to address some underbody rust. I have never worked on a transmission and am hesitant to do so. In the Atlanta area, I have called 6 shops and none of them will even let me bring it in to look at. Is it worth continuing to find someone to at least open and inspect it? Or should I leave it as is and just top off fluid when I put it back in the car. Thanks in advance. 

 

When it was running, driveline never gave me any issues. No clunk, vibration, hard shift, etc....

 

To make sure I know my car, the stock trans+diff for this model is the 3N71B automatic and r160? (Still figuring out how to post pics)

[ggzilla]

do NOT recommend a rebuild or a flush

 

The JATCO 3N71B will live forever unless it runs out of fluid. I recommend a filter change and fluid drain. And careful re-fill. Most failures occur after changing the filter, because the level is not filled correctly or because the gasket leaks or the filter wasn't put on correctly. It is fairly easy to get right, just care is needed. The owners manual has the nominal fluid amount and the level-checking procedure

[KirkLazarus]

Awesome. Fluid and filter it is. Thanks for the advice. 

 

[datzenmike]

3 hours ago, KirkLazarus said:

 

 

'70 510 2 door automatic...

 

...When it was running, driveline never gave me any issues. No clunk, vibration, hard shift, etc....

 

To make sure I know my car, the stock trans+diff for this model is the 3N71B automatic and r160? (Still figuring out how to post pics)

 

It's hard to abuse an automatic and why they last so long. Over heating kills them. Towing is the biggest cause of over heating. By the sound of it it's running fine. If the fluid is bright red your good to go. Yes I would change the filter and fill the transmission with fresh DEXRON III ATF.  I would not use the DEXRON Vl which is a full synthetic ATF. It's compatible but can begin to weep past old seals where regular DEXRON III will not. I wouldn't bother with a full flush but you can if you wish. Do NOT over fill. Top up, start engine and warm up for 15 min, then shift through the gears with brake on, check level and top it up if needed till it stabilizes at the full line. Always check when hot and engine running. It should take 6.75 US quarts, but as you are not replacing what's in the torque converter and coolant lines it will be less than that.  

 

Your '70 510 should have a Borg Warner 35 automatic in it. The 3N71B was introduced later, in April '71 510s.