FMX Transmission Issue

[bigfoot72]

Hi Everyone,

I took my 1972 Mustang to a shop to get the passenger side rear axle replaced because the current one was bent slightly from clipping a curb. When I picked up the car and was taking it home I very quickly realized the car wasn't shifting properly. When I got it home I added 1 1/2 quarts of Type F automatic transmission fluid since the marking was slightly below "add" to bring it up to where it should be but that didn't solve the shifting problem. Basically I can shift into park, reverse and neutral just fine. I can also manually shift from 1st to 2nd and back just fine too. The only thing is that when it is in drive the car stays in the gear it was already in. I know for a fact the car was shifting normally when i brought it to the shop and was shocked to find it wasn't shifting correctly when I took it home. I'm not sure if when the shop was replacing the axle that something could've effected the transmission? They claim they did everything properly with the axle and aren't sure why it's shifting this way. Any help would be much appreciated! 

 

[1sostatic]

Now I am not a transmission expert at all - but I think there are two vacuum hoses between eng bay and trans -- what do they do? -- can they leak? 

 

[bigfoot72]

Now I am not a transmission expert at all - but I think there are two vacuum hoses between eng bay and trans -- what do they do? -- can they leak? 

I was going to look at the vacuum lines today. I'd be surprised if there was a leak of some sort

 

[Bentworker]

They may have knocked the vacuum line off the modulator if they pulled the driveshaft

 

[bigfoot72]

UPDATE

The vacuum line that connects from the transmission to the manifold was disconnected. Car shifts fine now. So happy this problem was solved! Thank you everyone for your advice

 

[midlife]

Vacuum problem sucks, doesn't it?

 

[Carolina_Mountain_Mustangs]

You should keep the old axle. You can remove the studs and put in lathe and run between the centers in the axle and take a skim cut on the face and put new studs in.