4r70 cross member

[papy]

for those of you who have done the mods to the stock cross member how did you manage the frame mounted portion of the OE cross member that needs to be moved back - in my case i believe it is 3" ?
4r70w from a 96 explorer

drill/tap into the frame doesn't seem like a solid option - the original mounting holes have nuts or reinforced somehow and tapped from the inside of the frame

JP

 

[fordguy]

for those of you who have done the mods to the stock cross member how did you manage the frame mounted portion of the OE cross member that needs to be moved back - in my case i believe it is 3" ?
4r70w from a 96 explorer

drill/tap into the frame doesn't seem like a solid option - the original mounting holes have nuts or reinforced somehow and tapped from the inside of the frame

JP

Mine was 1 1/2 . Are you adding an adapter ring? I bought to used mounts, used the original holes, and extended by cutting and adding length I needed. BC Broncos has a nice one, but it is not cheap.

 

[papy]

Mine was 1 1/2 . Are you adding an adapter ring? I bought to used mounts, used the original holes, and extended by cutting and adding length I needed. BC Broncos has a nice one, but it is not cheap.

i vaguely remember reading somewhere that the 4r70 from and AWD was 3" longer and the 2WD was 1.5". It doesn't make sense to me but that's what i read- i have yet to bolt everything up

i was just thinking about adding some length to them. using the original holes i think is best

thanks

JP

 

[fordguy]

Does not matter if you are using the AA adapter, the cases are the same. I believe the AWD is actually shorter and is same bolt pattern as Atlas and NP205.

 

[papy]

this is what i read a few years ago which is why i thought the 4x4 version was longer somehow but it did not make sense to me then and now lol

everything else i have read says its 1.5" back

https://classicbroncos.com/forums/threads/starting-a-4r70w-swap.297364/#post-3222299

JP

 

[davisjstone]

I notched the original crossmember and made some extended crossmember mounts that used the original mounting holes. I copied the idea from a thread on here. I don't weld, so dropped it off at a fab shot and they helped me. I think I added 3" or 4" to the length.

Helpful threads:
https://classicbroncos.com/forums/threads/4r70w-crossmember-fab.271057/
https://classicbroncos.com/forums/threads/4r70w-advanced-adapter-help.319212/

 

[904Bronco]

I notched the original crossmember and made some extended crossmember mounts that used the original mounting holes. I copied the idea from a thread on here. I don't weld, so dropped it off at a fab shot and they helped me. I think I added 3" or 4" to the length.

I was posting but yours popped up B4 I could finish...

 

[papy]

I notched the original crossmember and made some extended crossmember mounts that used the original mounting holes. I copied the idea from a thread on here. I don't weld, so dropped it off at a fab shot and they helped me. I think I added 3" or 4" to the length.

Helpful threads:
https://classicbroncos.com/forums/threads/4r70w-crossmember-fab.271057/
https://classicbroncos.com/forums/threads/4r70w-advanced-adapter-help.319212/


View attachment 961688

I was posting but yours popped up B4 I could finish...

thanks for posting pics- nice brackets! i have several sets of the OE brackets so the plan is to cut them to the desired length and weld them together

JP

 

[papy]

I was posting but yours popped up B4 I could finish...

I was posting but yours popped up B4 I could finish...

would you happen to have the link to that thread? could have some more info i can snag up

JP

 

[904Bronco]

As stated make your own.

I bought some made by one of the bronco vendors once upon a time and I was disappointed by the quality of the pieces... Tolerances were so tight that they gave you Allen head bolts to fit it in the corner holes.

I do like the mounting Kit that Tom's sells, but when you have all the factory parts you need, it was just easier ($$) to make the mods myself.

Maybe you aren't doing a frame off? I make the mods to the crossmember, bolt it to the trans AA adapter and then drop it the engine/trans/t-case into position. With the motor mounts in the proper position, I can then drill the two holes needed on top of the frame brackets.

Be sure to chase the holes in the frame. New bolts, grade #8 is what I suggest. Cheap insurance.

With the 4WD 4R70W and the AA adapter kit that has the spacer ring, the t-case shifters are 3" back. With the 2WD drive trans or if you remove the factory 4WD rear case, (which means you have to go into the trans to replace the output shaft) and you use the standard rear AA adapter that makes the t-case shifters 1.5" back.

I have Not used the AA 4WD trans with the AA adapter, so I am not certain if this means that the frame brackets need to be longer???

 

[papy]

this is excellent! thank you

JP

 

[Oldtimer]

I needed 1 inch for my 4sp top loader install. I slotted the brackets and extended them with a cut up bracket.

 

[turbotim2]

I notched the original crossmember and made some extended crossmember mounts that used the original mounting holes. I copied the idea from a thread on here. I don't weld, so dropped it off at a fab shot and they helped me. I think I added 3" or 4" to the length.

Helpful threads:
https://classicbroncos.com/forums/threads/4r70w-crossmember-fab.271057/
https://classicbroncos.com/forums/threads/4r70w-advanced-adapter-help.319212/


View attachment 961688

I did the same, 3" angle iron, 1/4" thick and 8" long. Used stock frame bolt holes. The 4R70W, AA adapter and D20 was 1-1/2" longer than stock.

 

[papy]

great! appreciate all the info

JP

 

[papy]

I notched the original crossmember and made some extended crossmember mounts that used the original mounting holes. I copied the idea from a thread on here. I don't weld, so dropped it off at a fab shot and they helped me. I think I added 3" or 4" to the length.

Helpful threads:
https://classicbroncos.com/forums/threads/4r70w-crossmember-fab.271057/
https://classicbroncos.com/forums/threads/4r70w-advanced-adapter-help.319212/


View attachment 961688

As stated make your own.

I bought some made by one of the bronco vendors once upon a time and I was disappointed by the quality of the pieces... Tolerances were so tight that they gave you Allen head bolts to fit it in the corner holes.

I do like the mounting Kit that Tom's sells, but when you have all the factory parts you need, it was just easier ($$) to make the mods myself.

Maybe you aren't doing a frame off? I make the mods to the crossmember, bolt it to the trans AA adapter and then drop it the engine/trans/t-case into position. With the motor mounts in the proper position, I can then drill the two holes needed on top of the frame brackets.

Be sure to chase the holes in the frame. New bolts, grade #8 is what I suggest. Cheap insurance.

With the 4WD 4R70W and the AA adapter kit that has the spacer ring, the t-case shifters are 3" back. With the 2WD drive trans or if you remove the factory 4WD rear case, (which means you have to go into the trans to replace the output shaft) and you use the standard rear AA adapter that makes the t-case shifters 1.5" back.

I have Not used the AA 4WD trans with the AA adapter, so I am not certain if this means that the frame brackets need to be longer???

so how do you figure out the slope/degree* of the custom frame brackets to know where to drill the holes?

 

[fordguy]

I did not worry about slope, I just slotted it an 1 1/2 back . Will get a pic tomorrow.

 

[Oldtimer]

so how do you figure out the slope/degree* of the custom frame brackets to know where to drill the holes?

The holes in frame are sloped (same Ford bracket can be used on left or right frame rail).
The frame at that point is level with floor of bronco bed, and ground if front and rear suspension lift is proper.
I suspect that the angle may be the same as crank centerline angle, but have no way to verify.

 

[904Bronco]

The holes in frame are sloped (same Ford bracket can be used on left or right frame rail).
The frame at that point is level with floor of bronco bed, and ground if front and rear suspension lift is proper.
I suspect that the angle may be the same as crank centerline angle, but have no way to verify.

As said above... Use the old brackets as a guide where to drill the holes in the new L - bracket. Your new L - brackets will be side specific.