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Atlas Support

Waterchicken

Waterchicken

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Mar 17, 2021
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There doesn’t seem to by any new tech on mounting an atlas in a rig since irate started. I know it was always a very controversial topic on PBB back in the day. So what’s everyone got to say? I was nervous about mounting a 4 speed separate from the trans in my XJ since it’s a tin can with body flex and everything. So I mounted the Altas and transmission together. I only know of a few people that have done this. Just looking to see what else has been done since this hasn’t been talked about in a few years. Current setup in my XJ is a LS/400/4speed Atlas. I haven’t run the atlas yet but I was running a 241OR behind the 400 for a while and never had an issue. I think the 4speed weights about 40ish pounds more than the old 241 so I really had to think about supporting that weight. Interested to hear what has been working for everybody.
 

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Ok I'll try and contribute some tech. This will be a good reminder to crawl under my rig and check things out since it just sits in my shop. I'll grab pics tomorrow.

I have a J10 with AMC 360/nv4500/atlas 4 speed and tons.

IIRC I have two of those regular/universal tranny mounts like what you can buy off the shelf at vatozone. One for the nv4500 and one for the atlas 4spd. They are both bolted to the same skidplate.

I definitely don't have any type of supporting ring on the end of the atlas.

I built the truck in 2009 and ran UA 2011. Drove it to moab several times. Towed my camper to the dunes several times and lots of wheeling. Never had an issue....
 
I wish the various manufacturers of aftermarket cases and doubler boxes would just provide a fuckin pair of bosses or tapped holes in the damn thing so people could use that instead of having a stupid overhung load on a tailhousing that's probably marginal from the factory (or just pure inadequate garbage if it's a GM or ZF5).
 
My motor, tans, and atlas is poly mount. Atlas is hung from the top and th400 is bottom mount. Imo it dont matter what you do as long as the mounting type you use matches throughout and nothing is mounted directly on skidplate so it doesnt see any up force from hits. I like the atlas support ring design but I have friends who do not mount the atlas anywhere with successful results as well. As for the 4 speed atlas, if it was mine, I would support the weight with the support ring.
 
I used the GM trans mount at the trans and the back of the 205 as close to center as the brackets would allow. The engine has round poly bushing which don't offer much misalignment. The GM mount has a lot of flex in all directions compared to the bushing style which has very little movement unless its rotating around the pin. Twisting and or moving a bushing style off of axis takes truck payload type forces, not something that is needed for the tail end of a aluminum trans. Engines sure, as the block is solid and fairly heavy and the bushing isolate the vibrations.
An important force to remember when picking mounting locations is driveline force when its high centered on a rock and pushing the T case upward.

F62D2B1F-3D0D-4AF7-A7BE-E6A773E59C9C.jpeg

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I always thought a single point mount in plane with the engine mounts was the preferred way to go. Essentially a tripod of sorts.

Seems everyone posting above is using multiple points with good results. I imagine it is less important in a tube chassis with good triangulation as opposed to a stock railed something or another though.

FWIW I plan to run a rear support on my Th350/Blackbox/205 combo with a bracket bridging/tieing the 205 to the trans on the underside.
 
The Unknown said:
I always thought a single point mount in plane with the engine mounts was the preferred way to go. Essentially a tripod of sorts.
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Any three points form a plane. The angle of the plane relative to crank center-line and separation from crank center-line matters for NVH stuff in ways I don't fully understand.

The Unknown said:
Seems everyone posting above is using multiple points with good results.
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You can get away with it if two of the points are close enough and flexy enough. Lots of OEMs have done this over the years.

The Unknown said:
I imagine it is less important in a tube chassis with good triangulation as opposed to a stock railed something or another though.
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Correct
 
The Unknown said:
I always thought a single point mount in plane with the engine mounts was the preferred way to go. Essentially a tripod of sorts.

Seems everyone posting above is using multiple points with good results. I imagine it is less important in a tube chassis with good triangulation as opposed to a stock railed something or another though.

FWIW I plan to run a rear support on my Th350/Blackbox/205 combo with a bracket bridging/tieing the 205 to the trans on the underside.
Click to expand...
i am curious how yours comes out.

here is mine its a magnum not eco but kinda close to same.
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These are old pics from like 2015, but I mounted mine on a bushing cradle that was supported by the inner skid plate sheet and bolted between the doubler and the Atlas.
There was then a piece of AR400 that covered the hole skid. These pics might make some sense, but the main thing is the weird mount. It uses poly bushings at like a 5" spread. This was for an SM465 to a Klune Goliath, to an Atlas II 4.3 in a TJ.

IMG_20150807_203048_zpsdu6snpth.jpg


IMG_20150807_205826771_zpsefdwaam4.jpg


IMG_20150807_210732_zpsvywmd9di.jpg


IMG_20150827_203821_zpslvaeroib.jpg
 
The engine needs two points of the tripod which are usually center of gravity for the block. This means the block cannot rotate or torsion with frame twist as this is probably the most common frame flex with a ladder style frame and even tube chassis.
That means the rear drivetrain should be able to twist or rotate in the chassis lengthwise. Up or down and side to side is minimal as most chassis are stiff in these planes. One rear mount is great for the tripod but doesn’t support the added weight of a heavy case and doubler so a second mount is needed along the length at the tail end of the case. Tripod V turns into Y by adding a fourth mount. The fourth mount can still rotate and twist with the third as they are inline so no rotation force is fighting with the chassis. Separating the tail of the Y into an H doesn’t allow the rotational flex. The closer the tail of the Y is to the centerline the better.
As stated earlier the mount type plays a big part in if the drivetrain can twist and rotate versus being almost solid.
 
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HYDRODYNAMIC said:
The engine needs two pints of the tripod which are usually center of gravity for the block. This means the block cannot rotate or torsion with frame twist as this is probably the most common frame flex with a ladder style frame and even tube chassis.
That means the rear drivetrain should be able to twist or rotate in the chassis lengthwise. Up or down and side to side is minimal as most chassis are stiff in these planes. One rear mount is great for the tripod but doesn’t support the added weight of a heavy case and doubler so a second mount is needed along the length at the tail end of the case. Tripod V turns into Y by adding a fourth mount. The fourth mount can still rotate and twist with the third as they are inline so no rotation force is fighting with the chassis. Separating the tail of the Y into an H doesn’t allow the rotational flex. The closer the tail of the Y is to the centerline the better.
As stated earlier the mount type plays a big part in if the drivetrain can twist and rotate versus being almost solid.
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Having cracked tcase housings before with an H style mount. I'm a believer in this. Everything will move no mater what so may as well plan for it.
 
This is what we did with mine. I have cracked this mount in half before. (Probably after a nasty roll) but the skid plate underneath kept everything "together" and I was able to drive it out. FWIW this is behind a low output 2.5L/AX-5.

build 036.jpg
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YotaAtieToo said:
Having cracked tcase housings before with an H style mount. I'm a believer in this. Everything will move no mater what so may as well plan for it.
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I too have leaned the hard way on an h mount less then a year to break the ears off the transmission. After that went atlas tail support without a single issue 4 years later
 
Mine is mounted off the front output housing bolts, then to the frame, think of like a factory Ford NP205 mount.
 
I'll be the odd duck here.


I did the traditional 3 point mounting system in my rig and then went beyond that.

I had a transfer case try to escape one time:laughing:

When I built my last rig The cross member was a bit extreme.

It was basically a tray that was bolted to the inside of the frame.

No bushings.

Mounted the trans the way you should. right in the center as you would find from the factory.


Bushing/mounts at the frame points is a recipe for disaster

That isn't where the twist happens,

It happens in the middle of the system.

From there I added 2 more mounts on the transfer case.

One on the rear output and one one on the front output.

The one in the rear was merely to support the back of the transfer case.

And the one on thee front was to prevent the transfer case from twisting and letting the bolts come loose.

Which has happened to me before. I can't get any pictures because I cant lift anything right now and I didn't get any when it was in the the rig before we took it apart. I'll look around though because I'm sure the mounts are currently with me and I know the case is, but I cant pick up the case and move it around.

The rings were built up in cad and are a little light, but they weren't built to support the power train just to support the transfer case and keep it from twisting.

It worked well in my last rig so I'll be doing it again in the next rig.
 
my th400+np205 has 3 point system. 2 rubber bushing from t case ends an one is supporting from adapter. engine has same bushings



picture.php
 
I did LS with poly mounts, NV4500 stock rubber HD mount on its own crossmember bolted to frame, no mount on NWF eco, TMR tail housing mount on Np205 which is poly, on its own crossmember. (will likely one day tie an antiwrap bar itnto this. Both cross members are 1/4 wall 2x2 square. 1/2" gr8 bolts on both sides.

I haven't wheeled it yet and not sure if I should swap the HD rubber joint on the NV4500 out for a poly mount or not. But seems strong as hell in the Y config.
20221012_174230.jpg
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Just finished this up today. Thanks to this thread, I adjusted my plan a bit. I was planing to install the rear transfer case support off center, out by the front output. From this thread, I installed it inline with the trans mount.

IMG_20230112_175129.jpg


IMG_20230112_163833.jpg




My situation is a little different in that I'll be using alum bushings in the engine mounts due to headers being right next to them. Poly bushings would just melt. The trans mount is a hard poly and the TC support is a softer poly. Hopefully that works out.
 
gt1guy said:
Just finished this up today. Thanks to this thread, I adjusted my plan a bit. I was planing to install the rear transfer case support off center, out by the front output. From this thread, I installed it inline with the trans mount.

IMG_20230112_175129.jpg


IMG_20230112_163833.jpg




My situation is a little different in that I'll be using alum bushings in the engine mounts due to headers being right next to them. Poly bushings would just melt. The trans mount is a hard poly and the TC support is a softer poly. Hopefully that works out.
Click to expand...


Anyone care to critique my mounting job? I just want to make sure there's nothing i screwed up or some glaring issue that will rear it's ugly head down the road.

The part I'm questioning is that if I run a string line from the engine mount to the transfer case support (in side view) the trans mount is ~2" higher than the string line.
 
gt1guy said:
Anyone care to critique my mounting job? I just want to make sure there's nothing i screwed up or some glaring issue that will rear it's ugly head down the road.

The part I'm questioning is that if I run a string line from the engine mount to the transfer case support (in side view) the trans mount is ~2" higher than the string
Click to expand...
 
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