TheAMCForum.com Homepage
Forum Home Forum Home > Competition > Drag Racing
  New Posts New Posts RSS Feed - Gremlin driveshaft loop
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

Gremlin driveshaft loop

 Post Reply Post Reply Page  12>
Author
Message
WesternRed View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Aug/03/2010
Location: Australia
Status: Offline
Points: 5787
Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Topic: Gremlin driveshaft loop
    Posted: Oct/25/2018 at 11:01pm
Has anybody got some pictures/details of how they constructed and installed a driveshaft loop in a Gremlin? Now that I am running in the 12's, I probably need one, just not sure of the best way to go about it. Car is running the stock floor pan.
I've finally given up drinking for good...........now I only drink for evil.
Back to Top
Trader View Drop Down
AMC Addicted
AMC Addicted


Joined: May/15/2018
Location: Ontario
Status: Offline
Points: 6762
Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Oct/26/2018 at 12:19pm
Don't have any pictures. A friend wanted one and he took dryer duct material and riveted together the loop, attachment tabs. He used longer seat belt bolts to bolt from the bottom thus not needing to cut or drill.
I just fabricated the loop from his model. I used 1"x 3/16" for the oval loop that fit the tunnel and welded two tabs on an angle to attach to the bolt holes.
He installed it so I never seen it afterwards, stated it fit up just fine.
He blew a u-joint (not much damage done) but wanted to contain the driveshaft if it ever happened again.
Back to Top
PacerLarry View Drop Down
AMC Apprentice
AMC Apprentice
Avatar

Joined: Aug/02/2010
Location: New Lenox, IL
Status: Offline
Points: 103
Post Options Post Options   Thanks (0) Thanks(0)   Quote PacerLarry Quote  Post ReplyReply Direct Link To This Post Posted: Oct/26/2018 at 2:44pm
Not sure what you are running, but per NHRA rules, a drive shaft loop must be a minimum of 2 inches wide and 1/4" thick. I cut a 2 inch piece of 5" schedule 40 pipe (.258 wall thickness). Cut that across the diameter for 2 "C" shapes. Then 2 pieces of 1/4" x 2" flat bar welded in between them gave me the oval shape. 

Mounting braces then get welded and attached to the car where you see fit. Mine is integral to the trans mount. Again, per NHRA spec, the loop cannot be more than 6 inches back from the center line of the U-joint.
Back to Top
PROSTOCKTOM View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar

Joined: Jun/20/2010
Location: Indiana
Status: Offline
Points: 2427
Post Options Post Options   Thanks (0) Thanks(0)   Quote PROSTOCKTOM Quote  Post ReplyReply Direct Link To This Post Posted: Oct/26/2018 at 3:12pm
Having blown a front u-joint apart at 115 mph I can tell you to build it wider than 2" and cover the entire u-joint area. I shot the cap into the floor pan and it cut it's way 3/4 the diameter of the cap through the floor pan. I little more and it would have shot me in the leg. The last one I built was 4" wide and I also now run billet yokes with 1350 series joints. I got lucky the first time and going to make sure if it ever happens again I am prepared for it.

Tom  
Back to Top
tomslik View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Mar/07/2008
Location: Colorado
Status: Offline
Points: 680
Post Options Post Options   Thanks (0) Thanks(0)   Quote tomslik Quote  Post ReplyReply Direct Link To This Post Posted: Oct/26/2018 at 4:41pm
Originally posted by PROSTOCKTOM PROSTOCKTOM wrote:

Having blown a front u-joint apart at 115 mph I can tell you to build it wider than 2" and cover the entire u-joint area. I shot the cap into the floor pan and it cut it's way 3/4 the diameter of the cap through the floor pan. I little more and it would have shot me in the leg. The last one I built was 4" wide and I also now run billet yokes with 1350 series joints. I got lucky the first time and going to make sure if it ever happens again I am prepared for it.

Tom  


ya know, I've got a winter project now.....never though about the u joint coming apart and doing nasty stuff BESIDES just pole-vaulting the car

67 american 290/4speed
Back to Top
WesternRed View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Aug/03/2010
Location: Australia
Status: Offline
Points: 5787
Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Oct/26/2018 at 5:44pm
PacerLarry, when you say integral to the trans mount, do you mean attached to the trans cross member?

Our regs also call for 2" x 1/4" flat bar or 7/8" moly tube.
I've finally given up drinking for good...........now I only drink for evil.
Back to Top
WesternRed View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Aug/03/2010
Location: Australia
Status: Offline
Points: 5787
Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Oct/26/2018 at 6:33pm
I gather integral to the trans mount would look something like this:



Might be an opportunity to upgrade from the OE style trans mount in the process.
I've finally given up drinking for good...........now I only drink for evil.
Back to Top
PROSTOCKTOM View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar

Joined: Jun/20/2010
Location: Indiana
Status: Offline
Points: 2427
Post Options Post Options   Thanks (0) Thanks(0)   Quote PROSTOCKTOM Quote  Post ReplyReply Direct Link To This Post Posted: Oct/26/2018 at 11:33pm
I guess I should tell the rest of the story. The only thing that saved me was I had a balance tube welded in between the exhaust pipe. It beat it into a smashed mess, broke the extension housing, cracked the transmission case, and cracked the bellhousing. This is the best part of the story. It happened in late afternoon 5 miles from town. My friend Tom owns a transmission shop and we pulled the trans out, tore down a another transmission to replace all my broken parts. Rebuilt that case with my guts/valve body, replaced both u-joints in a spare driveshaft, and had that car out drag racing on the highway again by 11:30 pm that night. Next morning I had a new exhaust balance tube replaced and started building a wide driveshaft loop. That was in the summer of 1992 and to this day I have never taken the subject of driveline safety for granted. 

Tom

Back to Top
PacerLarry View Drop Down
AMC Apprentice
AMC Apprentice
Avatar

Joined: Aug/02/2010
Location: New Lenox, IL
Status: Offline
Points: 103
Post Options Post Options   Thanks (0) Thanks(0)   Quote PacerLarry Quote  Post ReplyReply Direct Link To This Post Posted: Oct/27/2018 at 11:03am
Red, your picture is similar to my setup. I had to fabricate a crossmember when I replaced my 258 with a 360 as my Trans was no longer in the factory location. For the body mounts, I used two pieces of 1/2" plate, and 3/4" tube crossing over to the Trans mount. For my drive shafts loop, I used two supports welded to the outside plates of the crossmember so the whole unit is a triangle.
Back to Top
amxdreamer View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jul/30/2008
Location: Vancouver, BC
Status: Offline
Points: 8494
Post Options Post Options   Thanks (0) Thanks(0)   Quote amxdreamer Quote  Post ReplyReply Direct Link To This Post Posted: Oct/27/2018 at 5:50pm
I know guys that have used these and just mounted with the seat rail studs. Not sure if that is approved so perhaps someone more familiar with the tech requirement can add to this.



Edited by amxdreamer - Oct/27/2018 at 11:41pm
Tony
Vancouver, BC
1970 AMX
1972 Badassador
AMO#10333
Back to Top
 Post Reply Post Reply Page  12>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2019 Web Wiz Ltd.

This page was generated in 0.422 seconds.
All content of this site Copyright © 2018 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or