transmission crossmember - Pontiac GTO Forum
Pontiac GTO Pontiac GTO Forum

» Auto Insurance
Wheel & Tire Center

Go Back   Pontiac GTO Forum > The 1964-1974 Pontiac GTO > 1964-1974 Tempest, LeMans & GTO Technical Discussions
Register Home Forum Active Topics Photo Gallery Garage Search Today's Posts Mark Forums Read Auto EscrowInsurance

GtoForum.com is the premier Pontiac GTO Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
Old 11-07-2012, 12:50 PM   #1 (permalink)
 
Join Date: Oct 2012
Location: Texas
Posts: 555
My Photos: (7)
transmission crossmember

Installed 455 with th400 into '66 Lemans convertible. (originally had 326 w/st300). Used original motor mounts, and location is perfect. Used original shift cable and bracket, re-drilled bracket at transmission- detents at shifter still line up-will even go into first if you press the button on shifter. Installed th400 yoke onto original driveshaft. Fit like a glove. Installed driveshaft (previously shortened 5/8") onto short output on trans., there is 3/4" between output and shoulder of yoke, (should be o.k., yes?). Only real problem seems to be the crossmember to frame mounts. Installed center bolts on trans. to crossmember, and mounting holes are 6 1/4" away on both sides from frame mount holes. Am I relegated to having to weld the frame mounts to the new location, or is it possible to use a piece of say, 1/4" plate steel on either side and use the existing holes to attach, to make up the difference? Or, is there a different crossmember I can use? I'm pretty excited about this, and need to go CRUISING SOON,!!!!!!!!!! (or I shall surely perish). THANKS!!!!!
gjones is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 11-07-2012, 06:32 PM   #2 (permalink)
64-67 Expert
 
geeteeohguy's Avatar
 
Join Date: Feb 2008
Location: Fresno, California
Posts: 6,797
My Photos: (2)
The '67 GTO was the only A body Pontiac to use the TH400 trans. And '67 was the first year. The transmission cross member and its location is unique. A '67 GTO cross member is pretty tough to find, and even then, your mounting holes on the frame will be off, as you discovered. To convert your '66, you will need to fab up your own mounting system, or fab up a custom cross member. It's about the only PITA part of the entire conversion.
geeteeohguy is online now   Reply With Quote
Old 11-07-2012, 06:33 PM   #3 (permalink)
64-67 Expert
 
geeteeohguy's Avatar
 
Join Date: Feb 2008
Location: Fresno, California
Posts: 6,797
My Photos: (2)
I forgot to mention, the '67 GTO CONVERTIBLE cross member is entirely different from the hardtop and post cars. Very rare, as it's a one-year, one-model application.
geeteeohguy is online now   Reply With Quote
Old 11-07-2012, 09:43 PM   #4 (permalink)
 
Join Date: Oct 2012
Location: Texas
Posts: 555
My Photos: (7)
66 crossmember

Thanks geeteeohguy, I pretty much assumed that was the answer. I really hate to butcher up a beautiful original piece like that crossmember (it made me kind of ill to bend & drill that little shift bracket at the transmission pan, as it was in excellent shape. But it works). Do you have any ideas as to whether or not my plate steel method will work? From frame brackets to crossmember, I'll use a piece of steel 3" wide x 9 1/4 long, line up the holes and bolt it together with case hardened bolts & washers. Then maybe weld an angle iron under that at the frame. Also, is that 3/4" clearance at the yoke to tailpiece o.k.? Cranked the 455 up today- SMOOTH AS SILK !!! I'm getting pretty antsy to drive 'er.
gjones is offline   Reply With Quote
Old 11-08-2012, 09:12 AM   #5 (permalink)
64-67 Expert
 
geeteeohguy's Avatar
 
Join Date: Feb 2008
Location: Fresno, California
Posts: 6,797
My Photos: (2)
I'm no engineer, but I know that whenever you divert a load from the straight line, the support system must be much stronger....a straight span is much stiffer/stronger than a U-shaped one. You'd be putting all the load on the bottm of the "U", and it would want to bend and sag. I think the best plan would be to bite the bullet and drill mounting holes in the frame where they need to be and do a straight forward install. Realistically, it's never going back to stock.
geeteeohguy is online now   Reply With Quote
Old 11-08-2012, 11:24 AM   #6 (permalink)
 
Join Date: Oct 2012
Location: Texas
Posts: 555
My Photos: (7)
crossmember

Gotcha. Was hoping for a "trick" of some kind- it's o.k., though. talked to a welding shop, we'll have 'er fixed up within the week! Thanks again.
gjones is offline   Reply With Quote
Old 11-09-2012, 08:29 AM   #7 (permalink)
 
allpawl66's Avatar
 
Join Date: May 2008
Location: PA.
Posts: 325
My Photos: (0)
Rule of thumb for yoke insertion insert fully in than back it out 1" . That allows for travel for rear to move with suspension . Also rule of thumb for drive-shaft measurement as well .
allpawl66 is offline   Reply With Quote
Old 11-09-2012, 01:53 PM   #8 (permalink)
 
Join Date: Oct 2012
Location: Texas
Posts: 555
My Photos: (7)
driveshaft

I understand the one inch rule, only I got 3/4 inch on final installation. Hopefully that'll be o.k.
gjones is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

  Pontiac GTO Forum > The 1964-1974 Pontiac GTO > 1964-1974 Tempest, LeMans & GTO Technical Discussions


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
68 conv. crossmember 1coolduck 1964-1974 GTO General Discussion 2 11-04-2012 02:46 PM
transmission crossmember question SammyLJ 1964-1974 Tempest, LeMans & GTO Restoration Discussions 1 03-08-2012 03:34 PM
Oil pan on crossmember MaL 1964-1974 Tempest, LeMans & GTO Technical Discussions 12 07-04-2011 11:49 AM
66 GTO crossmember mount brackets rays66gto 1964-1974 GTO parts for sale (Price & Pictures Required) 3 10-09-2010 07:02 PM
Missing Crossmember Bushing! wakerider017 Drive train, suspension, alignment and brakes. 0 05-06-2006 11:37 PM

Powered by vBadvanced CMPS v3.2.2

All times are GMT -5. The time now is 10:55 PM.



Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
SEO by vBSEO 3.3.2
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.