BC vs. Tom's 4R70W crossmember differences

[skrit]

What is the difference between the two besides price? Everything I've read on both seem to have issues with fitment, needing to grind and modify things. Is there a true bolt on option?

I saw this thread on the BC option but the thread dies without a conclusion/solution: https://classicbroncos.com/forums/threads/4r70w-crossmember-issues.314660/

 

[904Bronco]

I prefer Tom's... I used their crossmember on my last EB build and just picked up another for a 4R70W that I am doing for a Firefighter buddy.

I had to make these mods > increased the slots, longer #8 hardware with washers. Once done it fit perfectly.
I have done the factory crossmember mod as well, AA instructions could use a freshening and better pictures, but cost is good. Rubber isolators have to be ground on to fit.

Doug

 

[skrit]

I prefer Tom's... I used their crossmember on my last EB build and just picked up another for a 4R70W that I am doing for a Firefighter buddy.

I had to make these mods > increased the slots, longer #8 hardware with washers. Once done it fit perfectly.
I have done the factory crossmember mod as well, AA instructions could use a freshening and better pictures, but cost is good. Rubber isolators have to be ground on to fit.

Doug

That's great @904Bronco! Thanks for the pics! Seems like a simple mod - did you have to grind any on the AA adapter or cut the washers to fit like I've read elsewhere? Any chance you remember the length of bolts you ended up using?

 

[904Bronco]

That project was almost 3 yrs ago... I do seem to recall that the top washer(s) and doughnut(s) needed trimming to fit.

 

[Ol'Blue]

I'll be doing the 4r70w swap in a few months and curious as well. Both cross members seem to hang down more than the modified stock one. Any issues with exhaust or ground clearance?

 

[toddz69]

I really wish someone would make a crossmember for this conversion that mimicked the stock setup where the exhaust and the front driveshaft can go UNDER the crossmember. I recently helped with an engine swap that used a crossmember like this for its NV4500 transmission. I had to cut the exhaust in half to get it out for the engine removal. What a pain.

Todd Z.

 

[lars]

I really wish someone would make a crossmember for this conversion that mimicked the stock setup where the exhaust and the front driveshaft can go UNDER the crossmember. I recently helped with an engine swap that used a crossmember like this for its NV4500 transmission. I had to cut the exhaust in half to get it out for the engine removal. What a pain.

Todd Z.

Something like this?

 

[rocknhorse76]

Something like this?

View attachment 927894

Mine is similar but not as fancy as yours

 

[lars]

Mine is similar but not as fancy as yours

I see you have the same kind of front driveshaft as I do!

 

[gnsteam]

I prefer Tom's... I used their crossmember on my last EB build and just picked up another for a 4R70W that I am doing for a Firefighter buddy.

I had to make these mods > increased the slots, longer #8 hardware with washers. Once done it fit perfectly.
I have done the factory crossmember mod as well, AA instructions could use a freshening and better pictures, but cost is good. Rubber isolators have to be ground on to fit.

Doug

I used the Tom's cross member as well. And I had to do the same mods as 904Bronco. Plus I had to add a 1" riser shim between the AA adapter bracket and the cross member. The shim was need for additional front driveshaft clearance at the cross member and exhaust clearance issues.
See my build thread. Listed below in my signature line. There are pictures and explanations of the mods. Look at page 15, post #282. And pade 18, post #349.
I did not mention increasing the slotted holes but I did have to do that as 904Bronco did.

 

[Tricky Dick]

I really wish someone would make a crossmember for this conversion that mimicked the stock setup where the exhaust and the front driveshaft can go UNDER the crossmember. I recently helped with an engine swap that used a crossmember like this for its NV4500 transmission. I had to cut the exhaust in half to get it out for the engine removal. What a pain.

Todd Z.

I got Tom's AX15 crossmember and it looks functionally identical to that 4r70 on above. Not a fan of how low it hangs down, it gives up a lot of ground clearance for no reason but it was quick and easy up front. Eventually I'll have to make something better.

 

[Jaybr]

I'll be doing the 4r70w swap in a few months and curious as well. Both cross members seem to hang down more than the modified stock one. Any issues with exhaust or ground clearance?

I bought the Tom's crossmember and it wouldn't work with my Duff's 2 into 1 exhaust so I ended up just modifying the stock crossmember.

 

[bigmuddy]

Im using what is essentially a modified ZF crossmember from BC broncos. I do have one of the modified stock crossmembers that one of the parts houses was selling before they went under as well. I will eventually move on to something better but the tranny is in the rig at the moment, so thats a step in the right direction!

 

[rocknhorse76]

I see you have the same kind of front driveshaft as I do!

Hahaha yeah I took that pic during reassembly. The shaft is back in there now

 

[bigmuddy]

Speaking of driveshafts, I have an atlas II behind my 4r70w and the rear driveshaft (aftermarket) did fit but probably could use a slight trim on the splined end. The front wasn't even close.

Prior to this I was running a ZF with a dana20, in case someone runs across this thread in the future.

 

[fordguy]

I have made several, just take two frame brackets and add the needed length and use the stock holes. The crossmember can be modded by cutting out a section for clearance and flipping over and welding back on. You will have to cut the rubber mounts for clearance. You can pick up frame mounts for 20 dollars.

 

[skrit]

Update:

Received my Toms crossmember this week and got it installed. Other than trimming the washer and rubber mount - no other mods were needed (i.e. increasing bolt slot size, etc.). Instructions could have been much better but that's what this forum is for . A little tight at the D20 front output but I think it'll be fine. If not - I'll add what appears to be a spacer plate that is no where described in the instructions.

Also notice - the rear webbing of the center adapter bracket is facing towards the rear which is per the instructions. I had it backwards before I read through them.

 

[badandy73]

Update:

Received my Toms crossmember this week and got it installed. Other than trimming the washer and rubber mount - no other mods were needed (i.e. increasing bolt slot size, etc.). Instructions could have been much better but that's what this forum is for . A little tight at the D20 front output but I think it'll be fine. If not - I'll add what appears to be a spacer plate that is no where described in the instructions.

Also notice - the rear webbing of the center adapter bracket is facing towards the rear which is per the instructions. I had it backwards before I read through them.



View attachment 928427 View attachment 928428 View attachment 928429 View attachment 928430 View attachment 928431 View attachment 928433

@skrit

Been watching this thread and I've got the same thing going on with the Tom's unit. The clearance between the front output and the top of the cross member is too tight. Front driveline H-block doesn't clear, even with their lower profile HD (Tom Woods) shaft.

I contacted them about it a while ago when I went to install my new front driveline, and they said they'd work on some spacer plates- looks like they made it into their kit. I ended up having one cut myself out of 1/4" plate and going to give that a try.

 

[gnsteam]

Update:

Received my Toms crossmember this week and got it installed. Other than trimming the washer and rubber mount - no other mods were needed (i.e. increasing bolt slot size, etc.). Instructions could have been much better but that's what this forum is for . A little tight at the D20 front output but I think it'll be fine. If not - I'll add what appears to be a spacer plate that is no where described in the instructions.

Also notice - the rear webbing of the center adapter bracket is facing towards the rear which is per the instructions. I had it backwards before I read through them.



View attachment 928427 View attachment 928428 View attachment 928429 View attachment 928430 View attachment 928431 View attachment 928433

Have you actually installed and tested the front drive shaft clearance and the cross member. Here is a picture of mine without any shim.
Without a shim my drive shaft hit the cross member and was above the pinion yoke. How much suspension lift do you have? I have the Duff 2.5" lift. I ended up with a 1" shim, because I had the material on hand. I may have gotten by with as little as 5/8" shim. You can see in the second picture, where the paint is scuffed on the crossmember from the driveshaft.

 

[ntsqd]

Looks to me like installing the U-J U-bolts on that yoke is all kinds of not fun.