Jump to content

1967 Electra 225 Convertable Transmission Question


Guest twoska

Recommended Posts

The transmission of my 1967 Electra revs to high before switching out of first gear. I was told to replace transmission fluid (Car had been sitting for quite a while in a garage)

When I talked to a local shop guy he said that they would add a liquid (Think it was called Renu) to the transmission and it should bring it back to original shape. he said it was risky to drop the pan?

Is anyone familiar with this stuff? Should I try it out? Don't want to damage anything. If I need to replace the fluid would you recommend a synthetic?

Thanks. New owner, may have some dopey questions for you all !

Tom

Edited by twoska (see edit history)
Link to comment
Share on other sites

It might be that some of the shuttle valves in the valve body might be sticking (they work via a bias of fluid pressure against spring pressure, with the fluid pressure somewhat controlled by the governor). In that case, a fluid change with fresh detergent additives in it might work, but it might take a while rather than it happening immediately.

In the "old days", it was common to put a bottle of Berryman's B-12 carb cleaner in the trans fluid, drive the car a while, then pull it back into the shop and immediately change the trans fluid and filter. The carb cleaner is akin to "paint thinnner" and would remove any varnish which might have accumulated on the innards of the valve body. Using quality OEM-spec fluid is good, too. You can still find DEXRON III fluid in some brands of "all makes" fluid (read the back of the bottle and you'll probably find that the basic spec for that fluid is DEXRON III or Mercon V). In GM's orientation, their new DEXRON VI fluid superceeds all prior DEXRON and Type A specs, and I believe that it's a syn-blend fluid.

Should be NO problem with dropping the pan and doing a normal trans service, just like it used to be done when the car was newer.

ALSO, check all of the vacuum lines on the engine AND at the vacuum modulator (supply line and also the short piece of vacuum hose at the modulator). Low manifold vacuum at the point that it's needed (rather than at the main vacuum source on the intake manifold) can cause late shifts and harsh engagements.

If the thought of carb cleaner in the trans fluid might not be to your liking, there are many cleaner additives which you can find at the auto supply store or discount store, but the Berrymans B-12 works as good as many of them do. You don't leave the Berrymans in there very long, but long enough for the trans to get fully to operating temperature and stay there for a while . . . then you change it and put in new fluid. With a cleaner/additive designed more for use in automatic transmissions, you can usually leave it in there for a good while . . . or until the trans fluid turns "dark" from the "stuff" the additive has cleaner out of the valve body and such. Key thing, regardless of what you get, is to drive the vehicle in "D" basically, but also make sure to run the gear selector through each notch on the shift quadrant to ensure that all of the valves and such are actuated for a more complete "clean" activity. Make sure that, with the transmission fully at operating temperature, which is NOT the same as engine temperature, after driving it for about 30 minutes or so, that the fluid level is between "ADD" and "FULL", but not above "FULL".

Personally, I'd recommend AGAINST the "flush" activities which many shops now sell as an alternative to the more traditional "fluid and filter changes". The advantage of the flush is that it removes and replaces all of the fluid in the trans, rather than just in the pan, which can be good. Still, though, with an older vehicle, it would be better to do one initial fluid/filter/cleaner additive transmission service cycle and then follow it with another one a thousand or so miles later . . . especially if it's been sitting for an extended period of time and the fluid is anything but deep crimson and has the "new" smell to it.

As for "Renu" . . . I'm not sure about it. I don't like the advisory against dropping the pan, either. If you don't remove the pan, you don't know how much clutch material and such has accumulated there that needs to be cleaned out. If there's alot in there, even some chunks, that could be a good indication that something more might be needed than just new fluid. BUT you need to do the fluid and filter changes FIRST.

Make sure to get the correct filter/screen for your vehicle. Seems like there were several different ones in the earlier years of the THM400 transmission. An ACDelco would be perferable, but the ATP (aftermarket brand which many trans shops use) can be just as good.

Until you get the trans to acting as it should, it might be best to NOT use a fluid which is of a higher spec than the DEXRON III fluid. Once it's working well with that fluid, the next time you do a transmission service (24K miles or more later), THEN you might consider a higher-level fluid (or DEXRON VI) . . . for general principles. Main thing, for now, would be to get the fresh fluid and cleaner additive in there and let it work, then changing it . . . plus replacing any vacuum lines under the hood which might need replacing . . . and then doing a last change with fresh fluid. Then you can drive it and enjoy it!

Other than cleaner additives or additives/fluid types which might have some "seal expanding qualities, as some Valvoline MaxLife Dexron III fluid (and GM Automatic Transmission Conditioner) does, things should work just fine without any magic juice.

Just some thoughts,

NTX5467

Link to comment
Share on other sites

drop the pan and change the filter if you have never done so, and put some new tranny fluid in there

i change mine ever 25000 miles

and had one tranny now at 238000, no problems yet

and i have a tranny guy do it for me

he said if everyone changed their filter and tranny fluid every 25000 miles he would be out of business

Greg

Link to comment
Share on other sites

drop the pan and change the filter if you have never done so, and put some new tranny fluid in there

i change mine ever 25000 miles

and had one tranny now at 238000, no problems yet

and i have a tranny guy do it for me

he said if everyone changed their filter and tranny fluid every 25000 miles he would be out of business

Greg

What he said +1

Link to comment
Share on other sites

NTX5467...thanks for such a great post. Also wildcat1562 and brh. Looking forward to working on this beuty. I'll get pics up as soon as I can.

Anyone know of a good NY Buick club? Haven't googled yet but figured I would ask here.

Tom

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...