Having serious issues - 3rd tranny rebuild and still no reverse!!

[Corellian Corvette]

Ok guys this is really getting frustrating and I can really use some advice 

I have had my transsmission out and rebuilt three times, and each time I'm having exactly the same problem. This is in my 68 Charger with a 400BB (tranny is a 727 obviously)

The transmission will not go into reverse, nor will it shift into D. I get first, I get 2nd, but no 3rd and no Reverse.

At first the rebuilder though the problem was a mis-matched valve body (the case is from 69 and the Valve Body was from a 71), but he got a correct 68 valve body and it has the exact same problem.

He has air-checked the entire system and was convinced it was working properly. He builds transmissions professionally and has never seen this problem.

After three builds, he's worried that something may be wrong with the case and is considering starting over with a new transmission. He feels like he's ruled out the valve body being the problem.

Could there possibly be a problem internally in the case that is causing this?

If so, and I do get a new transmssion, how hard is it to convert to the single-post style neutral saftey switch from my 68? I don't want to do any re-wiring to deal with the three post switch.

Thoughts and advice GREATLY appreciated before I push this car off a cliff. 

Thanks

[twinscrew698]

Sounds Like a Linkage adjustment!

Have you tried without the linkage hooked up?

Have another person hold brakes as you manually shift gears from tranny itself without linkage hooked up!!

Also if that does not help Drop Pan and do the same and make sure That the ball and Sprocket that shifts tranny goes thru each sprocket..I have had them somehow bend a little and not go all the way in to the sprocket for a complete shift!

I know it sounds stupid but it has happened more than once to me especially right after installing Trans..

Don't remember about the wires!!!

Hope this helps somehow!!!

[flyinlow]

Reverse and third have the forward clutch applied in common.

To get reverse you need :  forward clutch and low/reverse band applied

to get 3rd  you need      :  forward clutch and rear clutch applied


When was the last time the trans. worked normally?

Since you tried a differrent valve body (a known good one I assume)

I suspect the forward clutch.

You can pressurize the trans with air. with the valvebody off. You can see the band apply or feel the clutch drum thud.


I am not a transmission guy but have had a couple apart .

[RD]

CC.. i believe it is the front clutch seals/drum as mentioned to you in your previous thread you posted on this.  John Kunkel mentioned the possibility of mismatching components from the 70 and earlier input shafts with the 71 and later as the bushing sizes being different and could cause for improper fluid flow in the front clutch drum area.

sorry to say, but the transmission needs to be dropped, the front clutch assembly removed and all seals replaced as well as checking the bushings to ensure that the appropriate parts are matched with one another.

have your trans builder put in a stock valve body from a working trans to see if things are different.  then and only then will he no for sure if its a valve body issue or hardpart (rotating assembly) issue.

let me know if you need any more help.

Jamey

[Corellian Corvette]

Thanks RD - I actually gave him your feedback on the last post, and this problem is after it was rebuilt AGAIN! 

He's now worried something might be wrong with the case, and is thinking of just starting from a transmission with all matched parts (he had to use three different trannys to assemble this one)

There is another tranny available locally, but it's a later model. If I were to get a 71+ BB 727 and start all over again, can that be converted to the single post style neutral safety switch?

Thanks!

[John_Kunkel]

If there was something wrong with the case it would most likely fail the air test.

After the last discussion did your builder check to see if the front drum and reaction shaft support are matched as was advised?

The single pin NSS will work OK in the '71 and later trans.