Builds Cruisermatt's FJ62 Build-up

[cruisermatt]

Currently working on re doing my motor mounts before i pull the broken transmission out (as it's locating everything and I can actually sort of move the truck around under it's own power, albeit forwards in 2nd gear only). Unfortunately the 80 series rear link bushings i had been very happy with for the first two years of the engine swap started suddenly degrading hard a few weeks before I left for my trip and throughout the trip completely degraded into nothing, this resulted in the passenger side frame mount ripping completely off the frame on the Rubicon. Not sure if it's the heat, the flex gaps in the rubber that those bushings have, or if it's just because they had 250k miles as control arm bushings before they were engine mounts, but I think this setup was just a touch too rigid which was a contributing factor in the bellhousing cracking, and I should have plated the frame on the passenger side to begin with so I decided to just re-do the setup. The joys of experimentation. And I'll never resort to those awful AA universal motor mounts

Time for a new setup.

I'm using a Envoy/Trailblazer bracket/mount on the passenger side (this is actually a driver's side bracket and mount but I only have this side for whatever reason so it get's used, no functional difference other then some clearance needed on the AC compressor bracket). I've accumulated a nice pile of various mounts and brackets from LS engines I've pulled from different applications, this one seemed to offer the most amount of cushion/fluff and seemed to be the easiest to build for as it sits pretty flat compared to the more common Tahoe/Silverado mounts that need a weird, inverted 45-degree mounting. As mentioned I only needed to make a new frame bracket. I'm thinking this large fluid-filled mount will take out that harsh impact loading the passenger side (compression) sees when flooring it in low gear. Regardless, this time I way overbuilt the frame mount for this side, all 1/4", including the frame spreader plate.

For the driver's side I'm sticking with a bushing/bolt setup, however loosing the 80 series suspensions bushing for a much larger (and fully rubber filled) leaf spring bushing for a Jeep Cherokee, it's large and has a easy OD, 2.5", and I had 2.5" pipe on hand, and it was about $8 and could get it same-day. Plus common easy replacement is a nice bonus.
Just need to finish welding the other side bracket to the frame and I will work on some frame tabs for this this side.

 

[cruisermatt]

Driver's/Tension side engine mount re-made to accept the Jeep spring bushing. Nothing fancy, re-used my laser cut 4-bolt plate, welded some 2.5" schedule 40 pipe to it, and the spring bushing presses in nicely after knocking down the pipe's weld seam with the die grinder.

 

[GLTHFJ60]

I'm not sure this is a good idea. Having a cush PS mount, solid rubber DS mount, and solid rubber trans/t-case mounts. The cush PS mount is going to crush more than the others, and cause bellhousing and/or trans mount stress.

 

[cruisermatt]

I'm not sure this is a good idea. Having a cush PS mount, solid rubber DS mount, and solid rubber trans/t-case mounts. The cush PS mount is going to crush more than the others, and cause bellhousing and/or trans mount stress.

until you take frame flex into account, which I didn't with my original setup.
The DS mount and the trans mount are sleeved rubber bushings, but they're rubber, not solid. There's flex there. Minimal but it's there.

i choose the cushy mount for the passenger side not only because of it's cushion in compression but also available flex left/right and forwards/back as well

I should mention i am also considering adding a crossmember under the engine bridging the frame mounts.

 

[GLTHFJ60]

The crossmember will reduce frame flex, not increase it.

I've always understood that each drivetrain mount should compliment the others. All cushy or all solid rubber, or all solid poly, etc.

 

[cruisermatt]

The crossmember will reduce frame flex, not increase it.

I've always understood that each drivetrain mount should compliment the others. All cushy or all solid rubber, or all solid poly, etc.

Correct, why would I want to increase frame flex? I don’t.

I don’t agree that the second part is a rule. In my opinion it is more of a case by case basis. For example we know a completely solid mounted drivetrain in a super stiff race car chassis works. But a completely solid mounted drivetrain in a regular leaf spring 60 chassis probably wouldn’t work, maybe with a 2F/H42 where everything is cast iron and super heavy, but certainly not with all the lightweight aluminum parts I have, aluminum transmission tailhousing, bellhousing, engine block, etc

My point being I don’t think a blanket statement rule applies.

The problem with having everything soft mounted in my setup is my low gearing and relatively higher horsepower. Throttle response and driver’s side mount longevity becomes a problem

 

[cruisermatt]

I also didn’t mention that I actually think I have too much rotational allowance at the transfer case with the parallel bushing. So I think too much transfer case movement and a ridgid engine mounting that I had before, combined with 60 series characteristics, led to my issues.

I think a bit more engine mounting flex allowance and a bit LESS transfer case mounting movement allowance and I’ll be golden.
I’ll be sticking with a poly bushing at the transmission but rotating it 90 degrees.

 

[underseaer]

I love this forum because sometimes I think I know things about vehicles... and then I read something like this and realize "oh no, i definitely don't actually know anything at all"

 

[The Phoenician]

I love this forum because sometimes I think I know things about vehicles... and then I read something like this and realize "oh no, i definitely don't actually know anything at all"

It's why I stopped reading, only pictures for this guy.

 

[NeverGiveUpYota]

 

[cruisermatt]

I love this forum because sometimes I think I know things about vehicles... and then I read something like this and realize "oh no, i definitely don't actually know anything at all"

Both @GLTHFJ60 and I really like to dig deep into the details and really analyze this stuff and make sure we aren’t doing things blindly. we’ve become good friends as a result

 

[GLTHFJ60]

The problem with having everything soft mounted in my setup is my low gearing and relatively higher horsepower. Throttle response and driver’s side mount longevity becomes a problem

Right, stiffening the frame is going to focus more of the movement in the drivetrain mounts.

The centerline of rotation for the drivetrain should be the crankshaft. My thinking is that if you have dissimilar mounts ds/ps on the enigne, then you've moving the centerline of rotation towards the stiffer mounts DS+trans mounts, which would put MORE stress on the driveline cases and bellhousing. I'd guess you'll wear out transmission mount(s) faster as a result.

In my situation, I have the same (relatively soft) mounts on the engine, mounted pretty parallel to each other, with two poly mounts on the trans/tcase on the centerline. It's been a solid setup for me.

I understand your dilemma, but I think the issue wasn't the fact that your PS mount is too stiff, but that it couldn't hold up to the stresses of being a motor mount.

Anyway, I understand your line of thinking, and am interested to see if it works well. Post pics of your newly revised driveline mounts once you're done.

 

[cruisermatt]

The centerline of rotation for the drivetrain should be the crankshaft.

Currently my trans mount is very close to the crankshaft axis and is un bound. Several who have seen my setup think that is the root of my issues, basically forcing the engine mounts to do all the work because the transmission can pivot back and forth on its poly bushing. Which it definitely did this when the motor mounts were worn out which is why the frame bracket broke.

 

[cruisermatt]

Yes what I'm doing is unconventional but if it's not clear so is everything I do to this truck

 

[GLTHFJ60]

Currently my trans mount is very close to the crankshaft axis and is un bound. Several who have seen my setup think that is the root of my issues, basically forcing the engine mounts to do all the work because the transmission can pivot back and forth on its poly bushing. Which it definitely did this when the motor mounts were worn out which is why the frame bracket broke.

I disagree. Factory FJ60 mounting arrangement has the trans mount close to the centerline. What do you mean "unbound"? The drivetrain is supposed to rotate around the trans mount.

Bracket failures due to failed mount bushings should be blamed on the mount bushings themselves, not necessarily on the mount locations.

 

[cruisermatt]

I disagree. Factory FJ60 mounting arrangement has the trans mount close to the centerline. What do you mean "unbound"? The drivetrain is supposed to rotate around the trans mount.

Bracket failures due to failed mount bushings should be blamed on the mount bushings themselves, not necessarily on the mount locations.

The factory 60 trans mount is a 8” wide rectangle and not a bolt through a sleeve.
Yes the drive train should move around that center line however I think should have some resistance. Like I said I think there’s a “Goldilocks” solution for me and I think I am there. A bit more, not a ton, engine freedom via a more cushioned compression side mount and a slightly more restrictive transmission mount.

I’ll drive it before I change the transmission mount so we’ll see how it looks. Only in 2nd gear but should get a decent idea.

 

[Cruiserdrew]

I was on the Rubicon that same time frame (started Saturday and finished Wednesday) and we should have crossed paths. Maybe you went by me when we were camped at Spider lake, which is off the trail a bit. Otherwise, I don't see how we missed you.

How did the climb off the slabs go for you? That can be tricky uphill as can the whole Big Sluice complex. How did you get past Decision Tree on upper Big Sluice? Good for you for sticking it out. Not wise but glad you made it work.

Bad luck with all that damage. I don't like ratcheting lockers either and believe all that loading and release stress increases the risk of parts breaking.

 

[cruisermatt]

I was on the Rubicon that same time frame (started Saturday and finished Wednesday) and we should have crossed paths. Maybe you went by me when we were camped at Spider lake, which is off the trail a bit. Otherwise, I don't see how we missed you.

How did the climb off the slabs go for you? That can be tricky uphill as can the whole Big Sluice complex. How did you get past Decision Tree on upper Big Sluice? Good for you for sticking it out. Not wise but glad you made it work.

Bad luck with all that damage. I don't like ratcheting lockers either and believe all that loading and release stress increases the risk of parts breaking.

I started at Tahoe Sunday morning and finished for the night just past Mile marker 4.2. Basically didn't stop other then when I broke and when I was waiting behind those Jeeps.

There was only a few spots that were challenging but i still got over them all. Not sure what Decision Tree is but I'm going to guess it's the one I dented my right fender on is it the squeeze between the tree on the right side and big rock on the left side (when running the trail backwards) that's on the rightmost part of the trail? Past the hard part going up Big Sluice?

I think with a proper rear locker like an ARB or Harrop I would have done the whole trail in 8ish hours and been off it that evening.

 

[Cruiserdrew]

Yep, that's the tree.

The trail can be done in a day but that's a boat load of work. 2 days is better, 3-4 days even better so you can camp more than 1 night in a single spot. Saturday to Wednesday was nice and relaxing and we didn't break anything significant.

That really is epic carnage, and I can't believe the locker damage did not damage the axle shaft too. Or maybe I missed something. But as I said, that was a fearless move to continue after that break. I for sure would have gone back to the springs, done some field repairs and gone home (though cadillac hill, uphill this year was no daisy filled field).

 

[cruisermatt]

Yep, that's the tree.

The trail can be done in a day but that's a boat load of work. 2 days is better, 3-4 days even better so you can camp more than 1 night in a single spot. Saturday to Wednesday was nice and relaxing and we didn't break anything significant.

That really is epic carnage, and I can't believe the locker damage did not damage the axle shaft too. Or maybe I missed something. But as I said, that was a fearless move to continue after that break. I for sure would have gone back to the springs, done some field repairs and gone home (though cadillac hill, uphill this year was no daisy filled field).

I lost probably seven hours combined due to the Jeep Jamboree delay and the breakage, and I was on the trail for only a few hours the next morning.
Nope, the stock axle shafts look flawless. 80 axle for the win.

As for turning around and heading back, you have to understand something. I wasn't even thinking about which direction I should go, I was just hoping I could get the truck to move more then ten feet under its own power. It was going nowhere in front-wheel drive even with the front locker. And I was broken 10 miles into the trail. After I got the rear put back together and it actually drove on it's own, I just decided to try the next obstacle and see what happened. And then repeated that a few more times. After that, and having traveled so far to do run this trail, I wasn't going to be denied just because of a few broken parts.