Hello, I'm installing a used GV from a friend that decided to convert his Challenger to a 5 speed manual.
My car is a '70 Charger. Every reference that I have read about these units mentions the need to dimple the tunnel for clearance of 2 nubs in the GV case. Oddly, MY case clears by a large amount. I have seen pictures of other b body installations and they all show the GV unit tucked up higher. I measured from the headers to the floor as a reference before and after swapping the unit in and the motor/trans are in the same position. This GV unit is one of their early units. Maybe they made some changes to the trans mounting pad?
The trans crossmember will not fit with the added girth of the extension housing, it hangs about an inch below its stock position. Something is obviously wrong. My options that I am aware of include:
1) Modify the crossmember with the GV/trans in its current position.
2) Raise the tail end of the GV/trans until it sits within 1/4" of the tunnel and modify the crossmember to fit via hogging out the mounting holes.
My question is with the acceptable angle of the GV/trans though. The car is lowered as you see in the pics, so it's not as if I will have the extreme driveshaft angles that would be present in a truck or van.
I may call the guys at GV tomorrow, but I feel a bit of a cheapskate since I bought this one used. I'd like to hear from customers if I could.... Thanks guys!

If the motor and transmission was properly installed in the first place (which I assume it was) then that is where it needs to be when you are done. Otherwise you will create a host of new issues such as improper drive line angle and interference problems.

I've done both GV swaps Auto and manual in B bodies using the earlier GV's,...in order to maintain proper driveline phasing, I needed to modify the factory transmission mount in both cases, although your attempting to position the engine/transmission driveline in the factory position, the shortened driveshaft will have a new increased angle, best to have the shaft made up, put everything together, then rephase the driveline, you may need to use perch shims to angle the pinion down, or lower the driveline angle a few degrees, with your car being lowered, it might help in that area, you want the engine/tranny centerline running parallel with the pinion centerline, in other words the tranny tail end pointing downward, and the front of the pinion pointing upward, but yet both on the same parallel angle to each other, the shaft should be no more 2 degrees opposite this parallel relationship of the engine and tranny,....get an inclination meter from a local machine shop supplier, no guessing

mike

I had to dimple my tunnel on my Supper Bee for the GV. The only other modifications were a shorter drive shaft and shimming the axle to obtain the proper pinion angle. From the picture of you car this is a long shot but, I am wondering what is the condition the rubber in your engine and transmission mounts? Maybe the engine has settled due to worn mounts. I have solid engine mounts and a urethane transmission mount on mine. Here is another suggestion, not related to your current problem. The GV controller kept randomly dropping the GV out of overdrive under cruse conditions. I by passed the controller and wired the engagement solenoid directly to the foot switch. Both the GV and I are now much happier.
Here is another bit of information I got from talking to the GV tech guys. The controller is very sensitive to voltage spikes, i.e. you turn the ignition on and the controller powers up, you then turn the switch to the start position. The voltage drop and rise from the starter engaging and dropping back off raises cain with the controller causing it to do strange things like shutting down etc. Mine was shutting down. The solution to this is the wire the controller to a switched circuit directly form the positive side of the battery that won’t see any voltage spikes during start up. I did this and it fixed my problem until I installed electric cooling fans on Da Bee. The voltage spikes returned when the fans came on. That is why I by passed the controller.

Great info, Thanks!
Regarding the positioning: The old trans mount was a factory rubber unit, and it was thrashed! It came out in several pieces. The trans yoke end was/is closer to the right side of center than the left, so for some time, the driveshaft has been working out of phase. It even had scuff marks where it had rubbed the rh muffler. Zero vibrations though. Am I just lucky there? The motor mounts are the Schumakers, left is the interlocking type, RH is standard and they are both in good condition. I want to tuck this GV up against the body as close as I can for ground clearance reasons. With the way that the trans and driveline were out of alignment before, yet still vibration free, is it wrong to believe that by repositioning the trans/GV to true centerline and tucked up as I have seen it done elsewhere, that it will be okay? Thanks again.

In your earlier response you mentioned

"Raise the tail end of the GV/trans until it sits within 1/4" of the tunnel and modify the crossmember to fit via hogging out the mounting holes."

Rather than hog the holes why wouldn't you just shim the mount between the adapter & the mount? Personally I'd raise the trans till it touches, do the dimples others have mentioned & then adjust the driveline angle as needed... The higher you tuck the trans/OD the better the ground clearance plus your header will also tuck in tighter...

I purchased a used GV unit also but for a truck application. I have made several calls to GV and talked with Mike. I had to get a few small parts from them and they are great to work with even though I did not buy a new unit from them. Good luck.

Don't guess on the driveline angles, most common problem for people trying to install aftermarket OD drivelines, and don't be afraid of modifying the floor or tranny mount/crossmember, the benefits of a good running OD offset the headaches of a bad vibrating driveline because your afraid of "altering" the car from stock......purchase an inclination gauge, and learn how to use it, measure your driveline angles on the car, as it sits compressed on the suspension, ok to work on a lift, as long as it's a drive on ramp style, you don't need level ground (within reason), if you reposition the car,to perform work at a later date, remeasure all the angles to confirm your progress

Mike

Some things I understand right away and other things take a little time.
Dayclona; I have the prop shaft in a shop. It should be done late today or early tomorrow.
Great advice from all and the help is truly appreciated.

This unit has the fixed yoke on it. Its an early unit but was rebuilt in 2006. With the car on jackstands and the rear axle jacked to its position at rest, I measured 38 1/2" from the center to center of the GV yoke to the 3rd member yoke. I told the counterman that number. He told me that this would be the center position of the travel for the slip yoke in the shaft.

The early GV units had a fixed yoke! The driveshaft has the slip yoke in it toward the front like the driveshafts in a 4wd.