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AMX Crossmember |
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mbwicz
Supporter of TheAMCForum Joined: Feb/20/2019 Location: Buffalo, NY Status: Offline Points: 1991 |
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Posted: Sep/10/2020 at 9:52am |
My 70 AMX had engine swaps in its history, and the motor mount area of the crossmember was torched out to fit the other engine(s). I acquired another crossmember from someone I trust. I believe that the one that was damaged was original to the car, the bolts holding it to the chassis were a bear to remove. 4 bolts with tapered seats and fine threads, like a European car's lug bolts.
Yesterday I got out the new crossmember to sandblast it, and notice that the 'replacement' piece appears to have had only one tapered seat bolt per side, and there is a witness that a flat washer was used on the second hole. My gut feel is that the tapered bolt was used to positively locate the crossmember to the chassis. Is there any reason to not trust one tapered bolt and one 'standard' bolt per side on this replacement crossmember? In the pic, the original one is on the top, and the pen is pointing to the lack of a tapered seat on the replacement. Thanks for any opinions. Mike |
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1970 AMX, one step forward, one step back. Both steps cost time and money.
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1948kaiser
AMC Addicted Joined: Jan/25/2015 Location: south west flor Status: Offline Points: 833 |
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my 72 gremlin with the factory v8 uses one bolt per slide and the one stud and a wheel nut per side. the stud gets put in first using anti-seize. takes two to hold the cross member up. then start the lug nut onto the stud and hand tighten to hold it in place. then the bolts using anti-seize should start by hand NO WRENCH and go in easily. that way they will not be cross threaded. the lug nuts line up the cross member into the correct position.
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Heavy 488
AMC Addicted Joined: Apr/27/2019 Location: In the Status: Offline Points: 3553 |
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If there was a problem with 1 taper per side i believe it would have been stumbled across many moons ago.
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AMXFSTBK390
AMC Addicted Joined: Oct/22/2013 Location: SF Bay Area Status: Offline Points: 3489 |
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I recently rebuilt the 390 in my 68 AMX. The engine cross member is mounted exactly as you described.
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Questions are powerful tools...what's in your toolbox?
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mark09
AMC Nut Joined: Dec/14/2012 Location: indiana Status: Offline Points: 281 |
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The pen points to where a weld-nut is missing/knocked off.
Should have 4 tapered "blocks" to locate. 2 get stud-bolts 2 get 1/2" Lug nuts. 1 nut and 1stud-bolt per side
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Mopar_guy
Supporter of TheAMCForum Joined: Jun/07/2009 Location: Ohio Status: Offline Points: 4826 |
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That's the way every 71-74 Javelin I've worked on is. I think they took 2 of the blocks out as a running change to save money because it's not necessary.
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"Hemilina" My 1973, 5.7 Hemi swapped Javelin |
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mmaher94087
AMC Addicted Joined: Apr/01/2008 Location: Arizona Status: Offline Points: 1691 |
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Mopar_guy is correct. I had NOS cross members and they all were the later type made for 71 - 74s.
Edit to include: If you are concerned about concours correct then knock two tapered nuts off your old crossmember with a cold chisel and use two old tapered bolts from the old assembly when installing the new. Edited by mmaher94087 - Sep/10/2020 at 7:34pm |
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Mike
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401MATCOUPE
AMC Addicted Joined: May/20/2010 Location: Salisbury, MD Status: Offline Points: 5367 |
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Mike M is 100% correct it was a running change to the crossmember. The old P/N supersedes to the one with single taper washer. It was a mid year 1970 change from what I have seen from parting out dozens of 70 Javelin's and AMX's.
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Ross K. Peterson
68X,GoPac,343,AT,52A(1stCar) 68X,GoPac,390,4sp,52A 69X,GoPac,390,4sp,64A 70X,GoPac,390,4sp,87A,8 70X,GoPac,390,4sp,BBO,8 70 Jav SST,390,AT,BSO 74MatX,401,AT,Prototype 74MatX,401,AT |
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mbwicz
Supporter of TheAMCForum Joined: Feb/20/2019 Location: Buffalo, NY Status: Offline Points: 1991 |
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Thanks for all the replies. I figured it was a running change along the way. Amazing all of these little details that show up when you start looking closely.
Mike |
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1970 AMX, one step forward, one step back. Both steps cost time and money.
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Steve_P
AMC Addicted Charter Member Joined: Jun/28/2007 Status: Offline Points: 3805 |
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Running change as Ross said. The second design is better. Two tapered locators like used in the first design will "fight" each other when it comes to front/rear location.
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