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4R70W Crossmember trouble

chris

Contributor
No more Rock Crawler
Joined
Nov 27, 2002
Messages
1,889
I have been working on the 4R70W install and have the trans mounted to the engine ok, I am using the AA adapter which fits fine. I originally modified the stock crossmember as per the crap AA instructions but the cross member seemed to be shifted to one side to work with the stock frame mount holes so I decided to purchase a cross member from Toms figuring I miss measured something with the stock crossmember I modified.

The crossmember came in today and I mocked it up but the transmission is still too far to one side to make the holes, I can't figure out why. I have removed the engine mount nuts and jacked up the motor trying to see if it needed to twist but there's no play there.

I've looked at flipping the crossmember the other way but that would put it too far back. The transmission bracket is in place just as the instructions call for it.

I had taken the engine out of the frame to paint the frame, it's the original frame, the same extreme motor mounts and the motor was in this frame with a C4 before and fit with no issues.

I'll give Toms a call next week but may one of you has run into this issue?
 

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MWM

Newbie
Joined
Apr 21, 2016
Messages
8
I had the same issue as you when I installed my 4r70w with the Tom’s crossmember and WH’s extreme motor mounts. Mine was about 3/4” off (yours seems to be quite a bit more) and what I did was use a ratchet strap around the tail housing to the frame to get it to line up so I could slide the bolts through. You may have to loosen your motor mounts slightly and retighten after you get the bolts through the crossmember.
 
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chris

chris

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I had the same issue as you when I installed my 4r70w with the Tom’s crossmember and WH’s extreme motor mounts. Mine was about 3/4” off (yours seems to be quite a bit more) and what I did was use a ratchet strap around the tail housing to the frame to get it to line up so I could slide the bolts through. You may have to loosen your motor mounts slightly and retighten after you get the bolts through the crossmember.
I haven't gone that far but I have put some side pressure on and it's hit the stops as far as the engine mount goes. The mounts are loose now and there's no play there.
 

71 CA Bronco

Sr. Member
Joined
Nov 25, 2015
Messages
732
Different cross member and mounts but I had the same issue. I ended up dumping the extreme motor mounts and went back to stock. Lossened everything up and bolted up the transfer case. It was easier to joggle the engine around with transfer case bolted up. It might help to put a hoist on the motor to take the weight off while you are joggling everything around. There should be a lot of movement available when everything is loosened
 

MWM

Newbie
Joined
Apr 21, 2016
Messages
8
I had to use the extreme motor mounts to get the extra height needed to get clearance from the lower pulley on the Explorer serpentine setup to the frame. If you don’t need the extra height maybe stock mounts would be best. I did put a lot of pressure on it with the ratchet strap to move it over. Other than drilling new holes in the crossmember this was what I felt was the best option at the time.
 

904Bronco

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Bronco Guru
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Sep 28, 2004
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San Martin, CA
Similar experience, Tom's, well I didn't really get an answer that I found acceptable.

I had to loosen motor mount bolts each side and lift the pan with a block of wood and floor jack to get things settled in place. But that was after I had to slot the holes on the support bracket.
Not much Aftermarket seems to just Bolt up :mad:
Pictures of the slotting...
 

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chris

chris

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Similar experience, Tom's, well I didn't really get an answer that I found acceptable.

I had to loosen motor mount bolts each side and lift the pan with a block of wood and floor jack to get things settled in place. But that was after I had to slot the holes on the support bracket.
Not much Aftermarket seems to just Bolt up :mad:
Pictures of the slotting...
904Bronco, great pictures! Looks like we have the exact same issues. I thought about drilling it out but you can see in the the picture attached that there is a brace welded in there and will prevent that. Even with the motor mounts loosed up and lifting the engine up I can't move it over far enough to make a difference.

I am going to see what Tom's says today but your not giving me a good feeling on that! lol

I think what I will end up doing is making a plate with 3/8" steel and welding in a set of studs on each side to match the offset holes.

The transfer case output is within 3/4 inch of being dead pointed at the 9inch rear, I really don't think moving the trans over 1.5 inches over to fit the holes is a good idea as it would throw that alignment out. It's in the natural position now. I also think it would put too much stress on the motor mounts if I were to pick up the motor and try twisting it to make it fit.

I believe this bracket was made for the AOD so maybe it fits that dead on but it's not working for the 4R70W very well, maybe they just need to add the extra holes to accommodate it.

I'll let you all know what Toms says today. And your right, nothing aftermarket fits, I always find that making one modification leads to one or more to make it work. Part of the hobby I guess.
 

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chris

chris

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Similar experience, Tom's, well I didn't really get an answer that I found acceptable.

I had to loosen motor mount bolts each side and lift the pan with a block of wood and floor jack to get things settled in place. But that was after I had to slot the holes on the support bracket.
Not much Aftermarket seems to just Bolt up :mad:
Pictures of the slotting.
So I had a nice conversation with one of the guys at Toms yesterday. He had a Bronco with an older AOD in the shop and he grabbed a new crossmember off the shelf and guess what, it was different and did not match the holes. He said it looks like they made some wrong.

He is having the Fabricator build me a new one and will ship it out in the next few days. He says he expects I will still need to force it the last 1/2 inch or so due to the Extreme Motor mounts and an option would be to go back to the stock motor mounts to gain a little wiggle room.

So now I wait again unfortunately.

As a side note, I am a little concerned with the lean back now. With the C4 the front serpentine pulley was just clearing the front crossmember, with this rear crossmember I have a lot more clearance and I am concerned that the valve covers will hit the fire wall, they were real close before. I thought someone posted about a spacer on the rear cross member just because of that reason?
 

tasker

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all knowing of nothing
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Jun 2, 2006
Messages
20,241
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NH
had to "massage" the custom crossmember my good friend Dave made up....took some time but eventually went together great
df.jpg
 

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71 CA Bronco

Sr. Member
Joined
Nov 25, 2015
Messages
732
Going back to stock motor mounts will give you more clearance between the firewall and tighten up the clearance on the crossmember. That was an issue with mine as well.

The spacer on the trans mount will help with your engine angle but the motor mounts are still a bit higher compared to stock. Least that was my experience.
 

lars

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Jun 29, 2001
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As mentioned, stock mounts will give you more lateral wiggle room. If clearance between the lower serpentine pulley and the crossmember is a problem, there are a few options. Someone on this board found a smaller diameter pulley (off a Saab, I think) that might resolve it. Another is to use a washer between the frame horn and the motor mount, to space it up a bit. Yet another, some have notched the crossmember to gain clearance. Lucky for me, for the usual "all Broncos are different" reason, mine fit fine.

And when I swapped in my NV4500 almost 20 years ago using an AA crossmember, holes weren't even close. Out came the drill motor, made new holes. Seems to be A Thing.
 
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chris

chris

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I swapped the Extreme Motor Mounts for stock motor mounts and the difference between the bracket location is amazing.

The first picture is the Extreme Motor mount and the whole assembly is too far to the Drivers side, the second picture now almost brings it to the hole and according to the Toms guys I should be 10 1/2 inches from the center of the Transfer Case Yoke to the Pass side of the frame which it now is. So with some luck the new cross member shoudl bolt right in. I hope so because the exhaust tubing is damn close to the trans and frame, not a lot of space left there.
 

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Cooter_76

Sr. Member
Joined
May 18, 2004
Messages
858
As mentioned, stock mounts will give you more lateral wiggle room. If clearance between the lower serpentine pulley and the crossmember is a problem, there are a few options. Someone on this board found a smaller diameter pulley (off a Saab, I think) that might resolve it. Another is to use a washer between the frame horn and the motor mount, to space it up a bit. Yet another, some have notched the crossmember to gain clearance. Lucky for me, for the usual "all Broncos are different" reason, mine fit fine.

And when I swapped in my NV4500 almost 20 years ago using an AA crossmember, holes weren't even close. Out came the drill motor, made new holes. Seems to be A Thing.
This is the smaller diameter idler pulley I used.
 
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