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Gremlin driveshaft loop |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5787 |
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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.
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I've finally given up drinking for good...........now I only drink for evil.
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6762 |
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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.
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PacerLarry
AMC Apprentice Joined: Aug/02/2010 Location: New Lenox, IL Status: Offline Points: 103 |
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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.
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PROSTOCKTOM
Supporter of TheAMCForum Joined: Jun/20/2010 Location: Indiana Status: Offline Points: 2427 |
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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
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tomslik
AMC Addicted Joined: Mar/07/2008 Location: Colorado Status: Offline Points: 680 |
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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 |
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67 american 290/4speed |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5787 |
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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.
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I've finally given up drinking for good...........now I only drink for evil.
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5787 |
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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.
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I've finally given up drinking for good...........now I only drink for evil.
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PROSTOCKTOM
Supporter of TheAMCForum Joined: Jun/20/2010 Location: Indiana Status: Offline Points: 2427 |
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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
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PacerLarry
AMC Apprentice Joined: Aug/02/2010 Location: New Lenox, IL Status: Offline Points: 103 |
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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.
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amxdreamer
AMC Addicted Joined: Jul/30/2008 Location: Vancouver, BC Status: Offline Points: 8494 |
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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 |
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Tony
Vancouver, BC 1970 AMX 1972 Badassador AMO#10333 |
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