Offset Transmission Crossmember

[BruiserOutdoors]

This has me scratching my head, feeling in over my head!

My setup: 408w stroker -> speed gems 2" adapter -> 6r80w -> Altas 3.0

I am in the process of fabbing a crossmember to support the 6r80w/Atlas. When clocking the Atlas, I found a potential happy medium degree/angle, shoved some wood wedges to space the Atlas away from rubbing the Frame, and went to work on designing brackets to utilize the factory crossmember holes.

I welded in a cross bar support to the braces I had machined to do the final cut and fit outside the vehicle. Upon inspection, my cross bar is "crooked"! It is offset further back on the passenger side (even though its spaced CCW, if I remove the spacers, the stagger will get worse I think). The transmission mount is nearly 1" staggered in relation to the frame.

This has been stumped, not sure which way to turn. Do I roll with it and finish building the crossmember (it looks absolutely ridiculous not being square!) ? Will the angled output shaft (not parallel with rear axle u-joint) cause me issues?

 

[hossbronco]

I’m surprised you haven’t gotten any comments on this yet. My only suggestion would be to try loosening the motor mounts and see if repositioning your engine slightly will buy you enough movement at the crossmember.

 

[hossbronco]

I’ll post your photo for you.

 

[BruiserOutdoors]

I’ll post your photo for you.

Thanks Hoss!!!

 

[BruiserOutdoors]

I’m surprised you haven’t gotten any comments on this yet. My only suggestion would be to try loosening the motor mounts and see if repositioning your engine slightly will buy you enough movement at the crossmember.

Slotting the motor mounts appear to only make the stagger worse. The wedge/spacers actually help the stagger.

 

[nvrstuk]

Your double carton joint will not be affected with that angle.

I can't see in the picture the attachment point between your bracket and the cross member.

I can see that the crossmember is not 90 deg side to side.
Without seeing how you're attaching it to your transfer case ( I'm assuming with 2 bolts that run vertically between the transfer case and and your cross member) I would weld your cross member at 90ﾟ to the frame and then just offset the holes for the 2 bolts that would bolt the cross member to the transfer case. In this case the passenger side bolt would not be equal distance front to rear- They might be offset by as little as quarter of an inch, maybe 5/16s

If you remove the wood wedge does the transfer case Go back to its original position and rest against the frame?

If it does you need to slot the 4 mount motor mount bolts that go into the engine block so you can rotate the engine independent of the mtr mount.
That way you are making the holes slotted slightly to allow the engine to rotate a degree or 2 without putting the rear motor mount in a bind.

It's important that whatever preload you have on the front motor mounts is the same as your rear motor mount-shouldnt be any if you slot those 4 mtr mount bolts ever so slightly.

I've been gone for two weeks or else I could have posted pics. No cell for 10 of those days.

The 2 bolts in my attached pic

 

[nvrstuk]

Here's another pic with an example of a little piece of blue tape where each of your new motor mount holes might be for your Atlas- - exaggerated a lot just to give you an idea

 

[BruiserOutdoors]

Here's another pic with an example of a little piece of blue tape where each of your new motor mount holes might be for your Atlas- - exaggerated a lot just to give you an idea

Thanks for the input and photos Brian. Squaring up the cross bar (will be 2x3 rect.) Is a good idea. I plan to use a standard transmission mount pedestal that fits the AA adapter holes with 2 studs that will go thru the rect tubing.

The Atlas will "spring" back against the frame with the wedges removed.

 

[nvrstuk]

You could leave it that way but I'd fix the bind against the frt mts.

The angle in my pic doesn't help much!

I had to hold the camera almost on the grd so I was guess-timating framing the pic correctly.

Looks like a combination of red Moab dirt and beach sand!! lol

 

[Broncobowsher]

A long time ago I did a V8 in a Ranger. Had a brand new roll of dental floss and tied one end to the pinion on the rear axle (centered) and pulled it tight to the crank pulley. It was a 2-piece driveshaft as well. it was anything but a straight line. Left and right it was all over the place. The engine was installed with a good twist, as in the tailshaft of the transmission was something like 4" off the straight line. They just did what it took to fit everything in there. In the end I pretty much just copied the original engine install. Centered the fan in the factory fan shroud and put the transmission in the factory crossmember mounting holes. It is not what you would expect. You would never see it just looking, unless you knew what you were looking for.

The Bronco has the engine a couple inches toward the passenger side. So many people never realize that. I remember installing headers and was scratching my head why the ratchet that fit great on the driver's side was such a tight fit to the inner fender on the passenger side.

I know the slots in the motor mount towers generally allow a lot of roll positioning of the engine. But those are sloppy slots. Loosen the nuts and I bet you can get a fair bit of transfer case side shift without binding stuff up.

 

[BruiserOutdoors]

New consideration/realization as I attempt to unbind things:

So the passenger motor mount (factory frame mount) is significantly "shorter" (horizontally) making the engine sit towards the passenger frame rail. Why did Ford do this? And how was it accounted for as you get to the back of the transfer case? If everything is square, I would imagine that the output shaft would be offset towards the passenger side similarly, putting it out of line with the rear yoke of the drive shaft. Any explanation?

EDIT: I just realized the rear 9" yoke is offset to the PS. DUH! I am used to working on chevy's ......




I am fighting measurements, not knowing where my end result should fall.


Some measurements I've taken:

- Inside frame rail to center of balancer (PS = 10.375, DS = 13.375.... yes 3 inches!) Is this off what it should be?

- Inside frame rail to center of output shaft of Atlas Transfer Case (PS = 11.375", DS = 12.125") Does this need to be centered between frame rails?

- Inside frame rail to center of transmission tailhousing (PS = 11.0625", DS = 12.1875"). This is close to the 1" offset that is claimed to be the norm for EB's (or is it 1" offset at the motor mounts?)


Trying to figure out when I know things are where they are "happy" and not in a bind. Trying to avoid excessive side load wear on drivetrain so I can fab the crossmember in the correct location.

 

[nvrstuk]

Triple check your measurements as I am doing this EXACT same thing on Shorty.

I am building a complete frame (less 20").and I am offsetting the engine to the PS like all stock Broncos are.

Exactly, I will get the exact dimensions for you off mine but the measurements from one side to the other should be very close to 2" difference. Meaning your engine is offset 1" to the PS.

This was done for D20 to frame clearance.


I just got my temporary mtr mts built today so I can totally understand what you are asking about.

Do not center btw frame rails but make the back the exact same as the front. So if the frt is offset 1 1/2" so should the rear.

You can verify this by taking inside frame width measurements at each point meaning if inside the frt frame is 23 1/2 and the back is 23 1/2 then you offset the crank (engine) the same distance side to side.

My frame I took OE measurements off of was the same width inside the frame rails. Looks like your's isn't??

Move the t case to the PS, make your mount, weld it up and keep moving.

 

[bmc69]

New consideration/realization as I attempt to unbind things:

So the passenger motor mount (factory frame mount) is significantly "shorter" (horizontally) making the engine sit towards the passenger frame rail. Why did Ford do this? And how was it accounted for as you get to the back of the transfer case? If everything is square, I would imagine that the output shaft would be offset towards the passenger side similarly, putting it out of line with the rear yoke of the drive shaft. Any explanation?

EDIT: I just realized the rear 9" yoke is offset to the PS. DUH! I am used to working on chevy's ......




I am fighting measurements, not knowing where my end result should fall.


Some measurements I've taken:

- Inside frame rail to center of balancer (PS = 10.375, DS = 13.375.... yes 3 inches!) Is this off what it should be?

- Inside frame rail to center of output shaft of Atlas Transfer Case (PS = 11.375", DS = 12.125") Does this need to be centered between frame rails?

- Inside frame rail to center of transmission tailhousing (PS = 11.0625", DS = 12.1875"). This is close to the 1" offset that is claimed to be the norm for EB's (or is it 1" offset at the motor mounts?)

gin
Trying to figure out when I know things are where they are "happy" and not in a bind. Trying to avoid excessive side load wear on drivetrain so I can fab the crossmember in the correct location.

ahh...I think we all assumed you knew about the offset to passenger side for the engine and trans. That's a "taken for granted" on EBs. LOL. I always figured it was to make more "room" for the front driveshaft.

 

[BruiserOutdoors]

ahh...I think we all assumed you knew about the offset to passenger side for the engine and trans. That's a "taken for granted" on EBs. LOL. I always figured it was to make more "room" for the front driveshaft.

Still seems way out of wack being ~3" different at the motor. As NVRSTK said, should be 2" different measurement wise. When I move the tailhousing of the atlas towards the PS frame rail, I'm hoping this corrects itself.

 

[nvrstuk]

Keep posting up progress reports.

If you would like you could call me later since that saves typing dozens of msgs.

I'm not the highest pay grade on this list but I can help ya get moving in the right direction.

 

[BruiserOutdoors]

Keep posting up progress reports.

If you would like you could call me later since that saves typing dozens of msgs.

I'm not the highest pay grade on this list but I can help ya get moving in the right direction.

thanks for the generosity! Will keep you posted.

 

[bmc69]

I'm not the highest pay grade on this list but I can help ya get moving in the right direction.

Wait ...wuht??..there is a pay grade?..and pay??? I been taken advantage of for so many years..

 

[nvrstuk]

Bruiseroutdoors-

Get this figured out and looking good?

 

[BruiserOutdoors]

Bruiseroutdoors-

Get this figured out and looking good?

Been busy with the holiday weekend/family get-togethers. Hoping by end of the day tomorrow to get it figured out

 

[nvrstuk]

I understand the weekend and company.

Same here...