Drivetrain mounting ideas (1 Viewer)

[Elfman]

STILL working on the NV4500 install. I've run into the classic stumbling blocks along the way here and I'm searching for some alternate mounting solutions for the T-case/ Trans. This project is CRAMPED!!!! All the way from garage space to space in the rig for this friggin humongous trans! Any way I've posted some pics of the mach up. Problems... no way to really disassemble in the future without major effort. Welding in the current configuration is going to be near impossible with my MIG. Don't really want to move frame crossmember.

Detail: 69FJ40, Gen1 SBC, NV4500 adapted to 3spd Tcase,

Q#1- Is bolting mounting brackets to the frame (if properly boxed) ok?
Q#2- Has anyone used the holes on the bottom of a AA adapter for mounting rather than the AA crossmember you see in these pics?


Pictures of your solutions very helpful.

 

[spotcruiser]

I didn't want to use the propeller mount for mine, so I made a mount to go under and use the mounting holes on the AA adapter. My mounts are bolted to the frame, but I sleeved the bolt holes with heavy tube, so there's no compression of the frame box.

 

[Elfman]

I didn't want to use the propeller mount for mine, so I made a mount to go under and use the mounting holes on the AA adapter. My mounts are bolted to the frame, but I sleeved the bolt holes with heavy tube, so there's no compression of the frame box.

View attachment 1427943

View attachment 1427944

EXCELLENT SOLUTION!!!! Thanks for the pics. Is the rubber isolator an AA part?

 

[spotcruiser]

The rubber mount is a GM transmission mount (TCI 952500) that you can buy at Jegs/Summitt/other places. You need to extend the slots on the mount base just slightly (less than 1/8") to work with the AA NV4500 mount.

 

[Elfman]

Gents, my compliments to your fab skils.
These both seem like venerable solutions. Thanks for the hope, ideas and PN#.

 

[Tin basher]

That gm trans mount comes in two heights as well the one pictured looks like the tall one

 

[RustyNailJustin]

What motor mounts are you using? Bushings at the block or the chassis?

 

[Elfman]

What motor mounts are you using? Bushings at the block or the chassis?

If I understand the question correctly they are on the chassis.

 

[RustyNailJustin]

If I understand the question correctly they are on the chassis.

View attachment 1428499

Got ya. I was curious because the trans mount should be the same as the motor mounts. What I mean by that is similar bushings mounted similar.
You will be fine using those motor mounts and the GM style mount at the adapter.

 

[Elfman]

What are the reasons why no one is using the factory holes in the bottom of the frame rail for mounting? Too weak? doesn't line up?

 

[Elfman]

In my cases, more effort than they are worth... plus they don't usually line up... plus exposes bolt heads to ground grinding... plus probably a bit weaker(grade 8 3/8" bolts x4 > 8mm x 4-6)

Grinding and weakening bolt heads isn't a big deal for a skid plate... but if it is drivetrain, failure means drivetrain on the ground. No thanks.

The alignment of holes could be usable with some trick fab, but the grinding and size of bolts is a good point. Stay tuned for some mach up photos. Hopefully tomorrow night.

 

[lcwizard]

Like @Lil'John we used the mount in the adapter then built a second crossmember so we could spread a skid plate under the t-case.
The 4500, being iron, probably would endure some rock contact. I'm not as confident about the aluminum t-case

 

[lcwizard]

@lcwizard is correct that I'm missing a skidplate in my pictures. That is going to be separate and after the front/rear linked suspension go in A keen observer would also note it was a 4l80 transmission with doubler and split case, not nv4500 and 1 piece case.

Here is NV4500 + skid plate using a split case using same style transmission mount:
View attachment 1435506
View attachment 1435507

Those are 1/2" bolts going into the frame.

yeah I noticed the Black Box and the deep pan on the slushbox. Pretty sure that combo is a tough fit in a 40 of somewhat normal proportions.
Regardless of the case selection the answer to the thread is, personally , I wouldn't use the 8mm holes that held the stock skid plate to support the running gear. Use cross bolts like you see in either of these two cross members. LilJohn has two 1/2" per side. We are using two 7/16" per side. 3/8 would even be OK as they would be put in a shear position. A single 3/8 gr5 has a shear of about 7000 lbs ( probably 2500 for the cheap imported bolts ). Bolting upward puts the bolt in tension. A tension joint requires a lot more diligence. Over torqued and the joint may fail in time from external tensile loads. Over torquing a bolt also encourages hydrogen embrittlement or stress cracking. Under tightening may cause the bolt to loosen in time.
If you place the bolts sideways through the frame the loads are carried in shear and there is no concerns about over or under tightening.
Use a locknuts and get close to proper torque and you're fine

 

[Elfman]

thanks for all the input. That linked suspension oughta be killer! I really like the appearance of @lcwizard 's skid plate/ crossmember combo and I think in time I will add to what I've started with here. getting the taper for the mounting tabs to match the frame was difficult as I didn't expect it to be so apparent. I selected channel iron for strength and ease of fabrication based on my toolage. The next step is mounting the angle iron to the frame. Problem: lands over one of those pesky holes in the frame.