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T84 to T90 Swap |
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northcoastsailor 
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Joined: 30 May 2018 Location: California Status: Offline Points: 58 |
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 Topic: T84 to T90 SwapPosted: 30 May 2018 at 2:14am |
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Good afternoon.
I recently bought a 45' Willys MB (Sorry, not a CJ2A). A previous owner swapped in a T90 transmission which I am fairly happy with keeping. The install was less than stellar, however. The original cross member was utilized to mount the T90 (moved aft a few inches), and was bolted to some L-stock with bad welds to the frame. I want to eventually do a frame off, and am wondering if a CJ2A crossmember properly drilled and bolted into the MB frame will give me the adequate droop I need to keep the T90. I am also prepared to put the hump into the MB tub floor. Also, should I look at sourcing CJ2A clutch actuation components and relocating their mounts (if not done so yet)? I'd have asked this question on MB centered sites, but I figure the backlash would be less here concerning my molesting of an already molested MB. I plan on using this as a near daily driver during the summer months, and would like to keep the reliable T90.
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oldtime
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Joined: 12 Sep. 2009 Location: Missouri Status: Offline Points: 4184 |
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Posted: 30 May 2018 at 2:23am |
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The T84 is shorter OAL than a T90.
The T90 is bolted to fore/aft centerline of the rear engine support crossmember.
So the T90 rear engine support crossmember needs be moved aft of T84 location. This change also effects the clutch control rod and control cable lengths. Edited by oldtime - 30 May 2018 at 2:37am |
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Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963) Zero aftermarket parts |
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northcoastsailor
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Joined: 30 May 2018 Location: California Status: Offline Points: 58 |
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Posted: 30 May 2018 at 4:53am |
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The conversion has already been done and the current crossmember (the original MB modified) has been moved aft. I just want to know if using a CJ2A crossmember bolted to the frame will give me the same adequate positioning of the T90 while cleaning up the appearance of the undercarriage.
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oldtime
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Joined: 12 Sep. 2009 Location: Missouri Status: Offline Points: 4184 |
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Posted: 30 May 2018 at 3:39pm |
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It's been 35 years since I had a Ford GPW... but from what I recall the rear engine support crossmember (AKA transmission crossmember) is nearly the same as the 2A crossmember.
The main concern is that MB, the GPW and the 2A all used the addition of horizontal bolts to secure the crossmember. A large outrigger bracket is attached at this #2 body mount position. The large outrigger bracket is part body mount and part crossmember support. Ideally the complete bracket should have been moved aft on the frame. But then doing that moves the #2 body mount bolts. You might also consider installing a 3A, 3B or early CJ-5 crossmember in lieu of your modified MB crossmember. Can you post a pic of what you have ?
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Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963) Zero aftermarket parts |
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northcoastsailor
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Joined: 30 May 2018 Location: California Status: Offline Points: 58 |
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Posted: 30 May 2018 at 6:34pm |
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I can't for another week or so. The owner took the original bracket, moved it back to match the T90's mounting location, and added L stock to gain the necessary distance below the frame to accomodate the T90's depth, and then attached the rear engine mount (crossmember) to that.
I was thinking of the late 2A - 5 crossmember that bolts vertically into the frame. |
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oldtime
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Joined: 12 Sep. 2009 Location: Missouri Status: Offline Points: 4184 |
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Posted: 30 May 2018 at 7:46pm |
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All of the later crossmembers intended for L or F 134's will work.
Avoid the V-6 crossmembers.
The offset and the depth are correct for T90's. The only functional difference is how these attach to the frame rail. (meaning two bolts per side.) |
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Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963) Zero aftermarket parts |
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Joe DeYoung
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Sponsor Member x 2 Joined: 20 July 2005 Location: Madison WI Status: Offline Points: 3358 |
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Posted: 31 May 2018 at 12:13am |
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OldTime, that's a great idea to us the 3A style cross member as conversion. much easier than relocating the 2a bracket.
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Joe DeYoung
to many jeeps, parts, and accessories to list here, but apparently enough to keep me in trouble with my wife. |
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northcoastsailor
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Joined: 30 May 2018 Location: California Status: Offline Points: 58 |
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Posted: 16 Feb. 2019 at 9:51am |
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So I've mounted the 3A crossmember in place temporarily. Question now is whether the frame rail should be reinforced where the crossmember bolts up to the frame. How do the original frames address this?
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athawk11
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Joined: 18 Jan. 2012 Location: Arvada,Colorado Status: Offline Points: 4151 |
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Posted: 16 Feb. 2019 at 2:24pm |
The 3A frame was constructed using heavier gauge steel, thus no additional structural support needed.
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1- 1946 CJ2A
2- 1949 CJ3A |
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northcoastsailor wrote: