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LCG HIJKLMNOP
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Mount bushings at both sides and one in the middle, allz the gives. Like this I - I . Seriously though, hard mounted shit comes loose as things move/twist/etc, bushing mounted stuff doesn't.
 

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Mount bushings at both sides and one in the middle, allz the gives. Like this I - I . Seriously though, hard mounted shit comes loose as things move/twist/etc, bushing mounted stuff doesn't.
Even worse, sometimes the part that comes loose isn't the bolted connection.
 

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Discussion Starter #163
Too much give is no good for those of us with tight clearances.

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LCG HIJKLMNOP
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Even worse, sometimes the part that comes loose isn't the bolted connection.
I read that on the internet too but here's the thing, in actual use it hasn't proven to be worse. What comes loose in your experience? In my experience the twisting of the frame in the middle caused 7 of 8 3/8" grade 8 bolts to break. I though it was overkill to use 8 3/8" grade 8 bolts and tap pads but hey, I was wrong. Similar to twisting a cookie sheet from both ends, the middle doesn't like to not be able to move. I don't think it was all the 4.0 jeep hp that broke it but that's just a hunch.

Too much give is no good for those of us with tight clearances.

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I'm not sure what poly bushings your using but the ones I have don't give much. They've outlasted my JJ's in my suspension so far. Combine the limited movement with the fact that they're mounted 12" away from the 3rd mount, how much movement do you think you're actually getting? Just my observations and experience with it.

I'd challenge you to get .200" of movement in the bushing, that would be about 1 degree of movement at 12" If you can't accommodate 1 degree of rotation of the drive train, you have other problems.

Just my $.02. Build is cool and coming along good!
 

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Discussion Starter #165
I read that on the internet too but here's the thing, in actual use it hasn't proven to be worse. What comes loose in your experience? In my experience the twisting of the frame in the middle caused 7 of 8 3/8" grade 8 bolts to break. I though it was overkill to use 8 3/8" grade 8 bolts and tap pads but hey, I was wrong. Similar to twisting a cookie sheet from both ends, the middle doesn't like to not be able to move. I don't think it was all the 4.0 jeep hp that broke it but that's just a hunch.



I'm not sure what poly bushings your using but the ones I have don't give much. They've outlasted my JJ's in my suspension so far. Combine the limited movement with the fact that they're mounted 12" away from the 3rd mount, how much movement do you think you're actually getting? Just my observations and experience with it.

I'd challenge you to get .200" of movement in the bushing, that would be about 1 degree of movement at 12" If you can't accommodate 1 degree of rotation of the drive train, you have other problems.

Just my $.02. Build is cool and coming along good!
Honestly, your probably right. My concerns would be with firewall and exhaust clearance but I won't know til I can find a transfercase. And I'm not sure when that will happen cause I can not seem to find one already pulled which means I need to cruise around local junkyards and pull one myself. With boating season here and me making a lot of progress on my wrangler it might be a little while unfortunately

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I read that on the internet too but here's the thing, in actual use it hasn't proven to be worse. What comes loose in your experience? In my experience the twisting of the frame in the middle caused 7 of 8 3/8" grade 8 bolts to break. I though it was overkill to use 8 3/8" grade 8 bolts and tap pads but hey, I was wrong. Similar to twisting a cookie sheet from both ends, the middle doesn't like to not be able to move. I don't think it was all the 4.0 jeep hp that broke it but that's just a hunch.
So based on a sample of one it's better for you. That's not statistically relevant. In my experience nothing has come loose because I used 3 mounting points. The vast majority of the time it works fine with outboarded trans mounts, but I have no interest in being the exception. It takes 3 points to establish a plane, using 4 points is overconstrained and now rather than your powertrain having 3 points attached to the twisting cookie sheet, you now have 4. The 2 rearward points being further separated from one another than the original single point now have more relative movement between them during chassis twist, so the same bushings are now trying to deflect much further under the same amount of movement. Plus instead of twisting(single bushing typically mounted cross-car) they're trying to deflect radially(dual bushings typically mounted fore-aft), which is even harder to do. There are 2 bushings absorbing that movement now, but the relative movement is likely a lot more than double what the single connection point was, so now even more of that stress is getting transferred into the bolted connections as well as the transmission housing and engine block. Will it fail? Probably not. Is it more likely to? Yep.


Edit: I just reread the posts above and want to clarify. I wasn't saying the single center bushing AND 2 outboard bushings was worse. That's better than either scenario on its own. I was saying even worse than a bolted connection coming loose is that sometimes the hard parts like the transmission case itself fail.
 

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Discussion Starter #167
This is all the info I was hoping to get when I first asked the question, thanks for all the responses.

Except now I think I'm going to re work the cross member on my wrangler too.

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LCG HIJKLMNOP
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So based on a sample of one it's better for you. That's not statistically relevant. In my experience nothing has come loose because I used 3 mounting points. The vast majority of the time it works fine with outboarded trans mounts, but I have no interest in being the exception. It takes 3 points to establish a plane, using 4 points is overconstrained and now rather than your powertrain having 3 points attached to the twisting cookie sheet, you now have 4. The 2 rearward points being further separated from one another than the original single point now have more relative movement between them during chassis twist, so the same bushings are now trying to deflect much further under the same amount of movement. Plus instead of twisting(single bushing typically mounted cross-car) they're trying to deflect radially(dual bushings typically mounted fore-aft), which is even harder to do. There are 2 bushings absorbing that movement now, but the relative movement is likely a lot more than double what the single connection point was, so now even more of that stress is getting transferred into the bolted connections as well as the transmission housing and engine block. Will it fail? Probably not. Is it more likely to? Yep.


Edit: I just reread the posts above and want to clarify. I wasn't saying the single center bushing AND 2 outboard bushings was worse. That's better than either scenario on its own. I was saying even worse than a bolted connection coming loose is that sometimes the hard parts like the transmission case itself fail.
I forgot I need to check normality on my data set in order to post on the internet.....my bad. Congratulations on knowing the 6 degrees of freedom, that's something at least. I completely get the 2 motor mounts and 1 trans mount constraining a drivetrain, I agree. I suggested bushings at the outer ends as a solution for a removable crossmember due to the forces it experiences on it's own and the failure I've had with it rigid mounted.

It's all good, it all works until it doesn't. Sometime it never doesn't.
 

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I forgot I need to check normality on my data set in order to post on the internet.....my bad. Congratulations on knowing the 6 degrees of freedom, that's something at least. I completely get the 2 motor mounts and 1 trans mount constraining a drivetrain, I agree. I suggested bushings at the outer ends as a solution for a removable crossmember due to the forces it experiences on it's own and the failure I've had with it rigid mounted.

It's all good, it all works until it doesn't. Sometime it never doesn't.
Yeah I took your initial response about a bushing at the trans and crossmember ends as joke/sarcasm. Took me a bit to piece together what you were actually getting at, that's why I added the edit to my last post.
 

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Discussion Starter #171
Np208 transfercase is in and clocked to tuck into the floorboards nicely. It hangs a little below the frame rails but I would rather have that then start hacking into the bottom of the tub. Started checking for driveshaft clearance and it looks like there is plenty of room. Gotta finish the steering box mount and trans cross member before the final clearance check then I have a lot of welding to do.


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Discussion Starter #172
I haven't been putting a lot of work into this lately, just collecting parts. I got a trunion kit for the rockers, and pretty much everything else to get the motor fired, and I scored a deal on a willwood brake/master cylinder set up. Thinking a hydroboost setup would be a nice complement to the cam so I have been researching that. I have never setup a hydroboost system before, anybody have opinions/experience on them?


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Yeah, go to the junk yard and pull one off an nbs silverado. Use a pump from the same truck, I'd buy new and pull the supply sensor thing out of it. The throw of the push rod can be fixed by moving the connection point to the brake pedal, or cut and drilled.
 

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Discussion Starter #174
Yeah, go to the junk yard and pull one off an nbs silverado. Use a pump from the same truck, I'd buy new and pull the supply sensor thing out of it. The throw of the push rod can be fixed by moving the connection point to the brake pedal, or cut and drilled.
Thanks for the tips!
I briefly looked at, and took some measurements of the booster on my duramax and at first glance looks like it would work.

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Discussion Starter #179
If fitment is an issue, some 90s mustangs, and some astro vans also had smaller hydroboost units. This is my planned route on the cj2a.
Fitment shouldn't be an issue, but I will remember that in case it does play an issue, thanks!

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Discussion Starter #180
Over the summer I lost all forward gears in the 4l60e in my wrangler...and well...I stole the 4l60e I had built for this truck to keep the wrangler going for the summer. As of yesterday the willys truck now has a 4l80e! I got a 2008 2wd one with supposedly only 90,000 miles. The output shaft is splined all the way so I should be able to get the right adapter for my np208 and just cut the splines on the output shaft down. The best part about a 2wd 4l80e is that is has a vss signal built into it already so I dont have to worry about trying to machine the adapter for one and adding a tone ring.

Going to order the rest of the parts needed to get the drive train bolted together this week and then start plugging away at getting it all put together and in the truck for good.


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