66gt350
Active Member
Found out this one the hard way this weekend. No I'm not talking about the easy difference in valve bodies or input shafts...
It all started out with Sabrina's new mustang. When she bought it, it had a race ready C4 in it, with a reverse pattern manual valve body that the PO wanted to take out of the car. We didn't want to drive back down to Sacramento, so he gave us a tranny to swap out. Well...this weekend, I go through the tranny to make sure that it wasn't just a POS core. It appears to have been rebuilt recently. So out with the old and in with the new.
The engine is the original 5 bolt bellhousing, so we take it off and put it on the new C4. We get it in with no problems. The problem arises when Sabrina goes to put in the driveshaft. It won't bolt up. The yoke is fully in the tranny, and the driveshaft is too long -- it won't bolt up to the rear end. I'm laying under the car scratching my head on what's going on. The tranny is bolted up correctly and everything looks good. I grab a tape measure and start measuring up the old vs. new tranny. The original tranny is shorter than the new one!! WTF!! The new tranny is an older body with the vent tube coming out of the side, where the new one has a vent on the top of the tailhousing. The main housing is similar, since the bellhousing bolts to the front pump, unlike the '70 C4 I
have under the bench that the bellhousing bolts to the main housing.
I had always thought that bodywise a C4 is a C4 is a C4...the only differences was the changes in valve bodies and '70's have a larger input shaft. I guess that's what I get for thinking!! I guess tomorrow, it's off to the driveline shop to get a driveline shortened by 1".
It all started out with Sabrina's new mustang. When she bought it, it had a race ready C4 in it, with a reverse pattern manual valve body that the PO wanted to take out of the car. We didn't want to drive back down to Sacramento, so he gave us a tranny to swap out. Well...this weekend, I go through the tranny to make sure that it wasn't just a POS core. It appears to have been rebuilt recently. So out with the old and in with the new.
The engine is the original 5 bolt bellhousing, so we take it off and put it on the new C4. We get it in with no problems. The problem arises when Sabrina goes to put in the driveshaft. It won't bolt up. The yoke is fully in the tranny, and the driveshaft is too long -- it won't bolt up to the rear end. I'm laying under the car scratching my head on what's going on. The tranny is bolted up correctly and everything looks good. I grab a tape measure and start measuring up the old vs. new tranny. The original tranny is shorter than the new one!! WTF!! The new tranny is an older body with the vent tube coming out of the side, where the new one has a vent on the top of the tailhousing. The main housing is similar, since the bellhousing bolts to the front pump, unlike the '70 C4 I
have under the bench that the bellhousing bolts to the main housing.
I had always thought that bodywise a C4 is a C4 is a C4...the only differences was the changes in valve bodies and '70's have a larger input shaft. I guess that's what I get for thinking!! I guess tomorrow, it's off to the driveline shop to get a driveline shortened by 1".
