78 sportscoach transmission help

[Mara]

i just bought a 1978 Chevy sportscoach  i drove it 75 miles to the RV park parked two days and the trans wouldnt engage. put fluid in and drove 26 more miles and parked tried to drive again and no forward gears. reverse is great but no drive gears. crawled under linkage all moving correctly do I just need to do a transmission service and dont know what type trans. it is.  PLEASE some one help. 

[Daniel Long]

Bet you have the 3 speed Torqueflight transmission. Those are reasonably bulletproof. Sounds like you have a shift solenoid issue. I'll have to dive back into my old manuals to be sure. This transmission was used on millions of Dodge vehicles so getting one should not be an issue if a swap is in your future.

[Mara]

yes thank you..... I did a vin check and it is a the 454 Chevy as per the vin decode. i will try the DOT 3. how long do i wait or do i just start it and try.

[Jack Wasmuth]

Start it up and put it in gear and then in reverse and then park and then drive. It may take a short time for it to circulate. Drive it at least 20-25 miles stop and go and higher speed to get it mixed and circulated good. You can repeat this if necessary.  

[Jack Wasmuth]

You can add 1/2 cup of DOT 3 or 4 brake fluid to the transmission and it will help the internal seals swell to help the pressure inside the transmission to work. This will not hurt your transmission at all.

If you engine is a 350  or a 400 you have a turbo 350 trans. If you have a 454 then you have a turbo 400 transmission.

[Mara]

Thank You

[Mara]

how do i do that pour it in and start it how long do I wait?

[Jack Wasmuth]

Daniel she has a chevy.

[Daniel Long]

So Sorry Mara! I read "Sportscoach" and assumed it to be a Dodge! With the Chevy 454 engine you likely have a TH400 3 speed transmission. I'd need to know what you mean by " the trans wouldnt engage". For this type of transmission if the governor gear is stripped then you can't get out of first gear (and that is pretty spongy) when driving. This is a safety component to keep you from stripping the transmission. The darn part is a plastic gear on the end of the governor gear (helps the transmission decide when to shift) and when it's stripped you can't get out of first gear.  The fix is simple and cheap.

[richard nance]

she says it works when she puts fluid in it.it sounds like the fluid keeps leaking out.i wouldn't put brake fluid in it.id buy transmission stop leak at the auto parts store.if the governer was bad she wouldn't have first gear either.id also replace the filter and pan gasket.id the trans by pan shape.go here. http://www.onallcylinders.com/2013/01/17/your-top-tech-questions-an...

[Rich Thomas]

My 78 Travelcraft ( a class "C" Chevy cutaway van with the 350 SBC) has a Turbo Hydromattic 400 - 3 speed transmission. I would guess yours will have the same. You can Google Chevy turbo 400 and find a picture guide of the oil pans on Chevy transmissions of that era and compare them to yours. There was basically two main ones used : the turbo 350 and the turbo 400. There was a couple odd ducks in there but not very common. Hope this helps out.

[Mara]

Hello some one...... I have tried all the suggestion. Down to pulling the valve body and cleaning every thing I could. To NO solution. I have resolved to replacement. Now how do I get the trans brake/drive line assembly out or pulled to get the old one out and new one in?

[Daniel Long]

Sorry to hear you're having so much trouble with the transmission. I have the Chevy P30 with the TH400 transmission and could send you the pages from the manual I have regarding removal/ install. I've done it twice on the Dodge and too many times to count on my little rear-wheel drive BMW's so the concept is the same but the Devil is in the details when disconnecting cooler lines, shifter couplings, etc. but it's not too complicated.