how far back for 4r70w crossmember?

[oldiron]

I am finishing up the 4r70w trans with the AA kit. Will notch the factory crossmember tonight.. Anyone have a solid number on how far back I need to move the xmember. My searching suggests around 2-2 1/4" . Can someone confirm this before I start cutting?
Thank
Greg

 

[Broncobowsher]

Which AA kit? There are a couple different ways of using AA kits, they are not the same.

 

[oldiron]

Its the 50-2704E kit for the 4r70W. adapter is 6". And it appears that the threaded holes for the mounts are not centered, i.e. the rubber mounts will fit in the machined pocket but the hole is way off.

 

[widowmaker77]

Its the 50-2704E kit for the 4r70W. adapter is 6". And it appears that the threaded holes for the mounts are not centered, i.e. the rubber mounts will fit in the machined pocket but the hole is way off.

Did you grind the end of bushing into a cone shape? They have to be modified to fit.

Jason does a pretty good job explaining

 

[Mori]

Which AA kit? There are a couple different ways of using AA kits, they are not the same.

Can you elaborate on that? I am about to buy an AA kit for my 4R70W to Dana 20 but I didnt realize there different ways of using AA kits. Please educate me. Thanks.

 

[Broncobowsher]

Can you elaborate on that? I am about to buy an AA kit for my 4R70W to Dana 20 but I didnt realize there different ways of using AA kits. Please educate me. Thanks.

The two off the top of my head...
The new output shaft and 1-piece adapter (like shown above). Original design started as an AOD adapter and updated to the 4R70W. You must rebuild the transmission to install the output shaft. Uses stock Bronco style transmission mount.
The other, often called the "ZF adapter". It works with a 4WD version of the 4R70W. Does not require a transmission rebuild (if starting with the right transmission in good shape). It uses a modern single transmission mount. But you have stacked adapters (transmission, factory 4WD tailhousing, aftermarket "ZF" adapter, transfer case). The more parts stacked, the more tolerance stack up you will have.

 

[Mori]

Can you elaborate on that? I am about to buy an AA kit for my 4R70W to Dana 20 but I didnt realize there different ways of using AA kits. Please educate me. Thanks.

Thank you. I never thought about going the ZF route, but now I better understand the advantages and disadvantages of the different ways of using the AA kits. Thanks Again.

 

[BUCKWILD]

I have found variances so I gust put the trans in and make new brackets for the frame and bolt them into the stock holes. i make a longer bracket with angle iron and reenforce it

 

[904Bronco]

The two off the top of my head...
The new output shaft and 1-piece adapter (like shown above). Original design started as an AOD adapter and updated to the 4R70W. You must rebuild the transmission to install the output shaft. Uses stock Bronco style transmission mount.
The other, often called the "ZF adapter". It works with a 4WD version of the 4R70W. Does not require a transmission rebuild (if starting with the right transmission in good shape). It uses a modern single transmission mount. But you have stacked adapters (transmission, factory 4WD tailhousing, aftermarket "ZF" adapter, transfer case). The more parts stacked, the more tolerance stack up you will have.

In addition... The first kit mentioned by Broncobowsher above moves the T-case back 1.5" and the second kit moves the T-case back 3"

 

[oldiron]

Did you grind the end of bushing into a cone shape? They have to be modified to fit.

Jason does a pretty good job explaining

I didnt. My wife found that video about an hour ago. The AA instructions dont mention this at all..in fact they say to use the stock tc mounts. On another note, the bushing sleeves provided in the kit dont fit either.
Thanks for the reply
Greg

 

[oldiron]

In addition... The first kit mentioned by Broncobowsher above moves the T-case back 1.5" and the second kit moves the T-case back 3"

I've triple checked my measurements and the difference between the c4 and this adapted 4r is 2 3/8" I plan at this point to engineer a fair amount of adjustability into the mount and call it a day.

 

[widowmaker77]

I didnt. My wife found that video about an hour ago. The AA instructions dont mention this at all..in fact they say to use the stock tc mounts. On another note, the bushing sleeves provided in the kit dont fit either.
Thanks for the reply
Greg

My bushing sleeves didn’t fit either. I believe they want you to use their kit provided sleeve inside the original but that didn’t work. So I ended up just using the original ones but I don’t like the way it fits. Too much slop. All in all I’m not too happy with this kit for the amount of money it costs. Personally I’d rather have the bolts go through the adapter with nuts like the original instead of screwing into aluminum threads.

 

[Broncobowsher]

I'm pretty sure I ditched the stock transfer case bushings and used some Jeep CJ traction arm bushings (from the spare junk bin). Couple drops of thread lock to keep the bolts from backing out.

 

[904Bronco]

Anytime that I have used aftermarket adapters, I have had to modify the Poly doughnuts and large washers to fit.
The metric bolts provided to hold the adapter to the Transmission housing don't grab all the threads, so I reuse the factory ones or buy longer ones.
The black and white directions provided can be a little vague for first timers...

Not complaining, just a fact... Being anal retentive is not a sickness