[6T5 Cat]

I'm in the process of installing a GearVendors over/under drive unit in my 65 Catalina. If you are considering installing one in a 65 to 70 full size Pontiac be ready to do some cutting on the trans hump. Notice that the cut goes back far enough to take out a portion of the front seat brace on the underside. If anyone is interested, I"ll take some pictures of the underside when I take the trans down (again) to fab a new hump. I am just getting back to working on the car since I had a Brain Hemmorage 1-1/2 years ago. Installing the new engine, installing a shaker hood scoop and doing this project has been good therapy, but my recovery has been very frustrating at times. Bob

[68Prix]

Bob, I am glad to hear you are making a recovery, and that this is good therapy. I am interested in the details, I was considering this upgrade to my 68 GP. Do you have a console you are going to use? and how does it affect that if you do? Does the seat still mount in the stock location? Pat

[65FATCAT]

I've thought about doing that conversion as one of those "way down the road" projects, keep us posted on the progress and by all means keep posting pictures, this may become a sticky one day.

[Fat Cat]

Welcome back to the hobby and glad to hear your recovery is going well. I just picked up a GV unit and am very interested in your progress and obstacles you've come across! Mine will be going in my 66 Catalina.

One thing I noticed right from the get go is the stock transmission mount doesn't appear to fit the GV unit.... did you have to fab a different mount to the crossmember?

[65catalina]

Bob,
That is great information. It doesn't look like it would work with a floor shift model because you had to cut right where the floor shifter mounts.

[67 Lamnas]

Originally Posted by 6T5 Cat

I'm in the process of installing a GearVendors over/under drive unit in my 65 Catalina. If you are considering installing one in a 65 to 70 full size Pontiac be ready to do some cutting on the trans hump. Notice that the cut goes back far enough to take out a portion of the front seat brace on the underside. If anyone is interested, I"ll take some pictures of the underside when I take the trans down (again) to fab a new hump. I am just getting back to working on the car since I had a Brain Hemmorage 1-1/2 years ago. Installing the new engine, installing a shaker hood scoop and doing this project has been good therapy, but my recovery has been very frustrating at times. Bob

Bob,

Very encouraging to hear you're back at it......

I have a GV in my '67 Lemans.........installation was similar to yours only some massaging of the trans tunnel.....not any cutting, though....

I only WISH I would have had the common sense to replace my 40 year old sagging body mounts BEFORE I had started the floorpan mods......I may not have had to do any or as much massaging........

Hindsight is always 20/20.....right??

[JKrull66]

Put one in my 66 GTO 4 spd. A little more work wacking your 4 speed to make it work. Added a 2 inch wide strip across the top and massaged it all into place. Worth the work... Fun stuff.
Good luck,
John

[AROWHED]

Great pics, please keep them coming.

[6T5 Cat]

Thanks to everyone for your thoughtful and encouraging comments.

68PRIX: Pat, the console will not work because the largest part of the GV unit required that I cut the part of the hump away that locates the shifter. And, the the bench seat will not work because of the same problem; the largest part of the unit is where the smallest part of the hump was located to accomodate the small cutout in the bottom of the seat. Buckets seats will work ok.

FatCat: You are correct that the original trans mount will not bolt up. The GTV unit uses the A body type mount which is 1/2 inch wider than the F/S bolt pattern.

I've done a lot of measuring and found a few issues that should be mentioned:

The stock 65 trans mount measures 1 inch thick and will not bolt up to the GV bolt pattern. Same goes for the replacement trans mount that's available through Ames, and it is also thicker at 1-3/8 inches. The Ford Mustang 6 cylinder engine mount that a lot people have mentioned as an alternative for the 65/66 F/S trans mount is 1-9/16 inches thick and must be re-drilled to match the bolt pattern of the GV unit. Another trans mount alvailable is the stronger poly mount which is 2 inches tall.

Eventhough it is 1 inch taller than stock, I've chosen to go with the poly mount, and I'll explain why. The GV unit trans mount is the same as an A body TH400 mount in location and height positioning. The 65 F/S TH400 mounting location is 1-1/8 inches farther aft and 1/8 inch higher in position. In addition to having to move the xmember forward 1-1/8 inches, the GV unit makes the trans sit 1/8 inch higher at that reference point along the centerline of the vehicle. Even that small amount must be considered because the trans yoke is now around 9 inches further back and will affect the u-joint angle. To compensate for the higher mounting position, taller poly trans mount, and the extended lenght of the trans, I calculated the desired height of the u-joint and modified my trans cross member to allow the trans to establish correct driveline angles. Also consider the shorter drive shaft will result in more exaggerated angles, too. In the end, the xmember will be 1-1/4 lower in the center. Here's a couple of pix.

I can only handle working a few hours a day because the stroke zapped me in so many ways...so please bear with my work pace. I'll report my progress and supply pictures. I hope this information will help someone who does this mod to their darksider in the future. I'll take 67Lamnas and JKrull66 word that the work is worth the effort. Bob

[BILL BOWMAN1]

Glad to see you back at it Bob. Let me know if I can help you with anything. I like to lift heavy things! LOL

[Fat Cat]

Wow, thanks Bob for the additional info. You really got it nailed down pretty good with all the adjustments to the xmember. After I did some more thinking, I started realizing more of this complexity, so I'm glad you mentioned what you did.

Now with my situation, it's not an option to loose my console and floor shifter that I spent oh so much time fabbing in last winter. I don't know until I dig into it more, but if I can get the GV to sit even a bit lower in the tunnel, I should be able to get the driveshaft angle back to normal with the adjustable upper contol arms I have on the rear axle. From what you've seen, is there any chance of dropping it down another 1/4 - 1/2" ?

[mike nixon]

Dumb question. Can you put the trans crossmember in a press and Persude it [or a large sledgehammer and a couple blocks] down at the mount area far enough to clear? I know 3/4 " is feasable because I've had to do that a few times in the past to increase clearance in the tunnel.

Mike

[6T5 Cat]

Hi Bill, good to hear from you. I'll take you up on the help sometime, and just to make you happy, I'll save all of the heavy lifting for you!! .

Mike: The BFH idea is good but there wasn't enough overall width to bend it down as mush as needed without the xmember becoming unstable on the sides.

[6T5 Cat]

Fat Cat I'll be installing the modified xmember tomorrow for a test fit and will have better clearance densions to give you. As it is now, I could probably take another 1/2 inch off if necessary and reinforce the bottom side.

[Fat Cat]

Yeah, let me know what you come up with and how much more room can be made. I can't foresee myself digging into my install for at least a couple months, but I like to know what I'm in store for to plan it out!

[6T5 Cat]

I have good news for those of you considering this mod for your 65/66 B-body; the GV unit will fit without cutting the floor with the changes I made to the xmember and by removing a portion of the front seat brace. Keep in mind that I am using the short tail shaft th400 from an A-body goat. Here are some pix of the modified xmember, underside of the floor mod to the seat brace, and the resulting trans hump clearance. I wound up using the Mustang 6 cylinder motor mount for my trans mount. Also I moved the xmember forward 1-1/4 inches. I'll send more pictures later when I repair my floor trans hump. I pulled a muscle in my neck so my work is on hold until it heals up.

[6T5 Cat]

Here's a couple of how I cut the floor brace. I'll post pix of the finished brace when my neck muscle gets better. Bob

[Fat Cat]

Very impressive work! That xmember looks amazing! It really looks like you were able to make quite a bit of extra room for the GV to fit under the trans tunnel without issue. What changed? Was it mostly from the thinner Mustang mount or did you drop the xmember mount even lower than before? Like I mentioned, I really like how nice of a job you did on the xmember, however I'm contemplating making my own now since there's a fair amount of modification involved anyway. That way I can also provide clearance for my 3" exhaust.

You mentioned using the short shaft th400 from a GTO.... what's the difference with that tranny? I always assumed that the bodies of the trannies were the same from the short shaft GTO's to the long shaft full size cars. Assuming that was the case, once the tail shaft is removed and the GV installed it should be the same either way....? Please clarify.

-Steve

[6T5 Cat]

Thanks for the kind words, Steve. The short tailshaft in the A-body cars is 4-1/2 inches long and the fullsize cat uses the long tailshaft which is 9-1/2 inches long. The GV extension (they have 2 sizes for the th400) has to match the length of tailshaft you have. Notice in the pix of my new trans the length of the extension between the trans housing and the GV unit.

I cut the center of the xmember mounting pad down 1-1/4 inches, then shaped and welded a 1/8" steel plate to it. Subtracting the difference in ht. of the motor mounts gives a total drop of 7/8". That put the extended length of the trans u-joint at the proper hgt., too. Bob

[68Prix]

Keep up the good work, I am sure thinking about this now that the unit can be tucked in there and not have to worry about the shifter and console. I hope your neck gets better also. Pat