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U-bolts on a D35 -> D44 swap

mhead

NAXJA Forum User
Location
Encinitas, CA
I've finally swapped in a D44 for the D35 in the back of my '92 XJ, I6 Auto tranny. When I got the D44 I was told it was from a '87 XJ. I guess the spring perches are just a little thicker on the D44 than the D35 since the U bolts are just a little short. No problem on the inner where the nut screws on completely, but on the outer where the stabilizer bracket attaches, the nuts screw on only about 1/2 way.

Can I leave as-is? Any source for U bolts that are just a tad longer?

Thanks!
 
Get longer U-bolts....
 
junk yard if you dont have teh cash for new ones. They streach over time and that is why most companies sell new u bolts with their kits. Get out the tape measure and hit the yard or parts storei have seen many people with - u-bolts off of something in the yard for $5 in their parts list...
 
Look in the yellow pages for a heavy duty truck parts supplier. They may be able to make them, or they can point you in the right direction. I have one down the street from me, and it only cost me $25 for all four. They came with all nuts and washers. You really want to replace with new ones. They stretch alot quicker than you think. Mine are about 4 months old, and I was able to tighten them up a full turn the other day. And no, it's not because they became loose.
BTW, the u-bolts are just soft steel, that is why they stretch and should'nt be re-used
 
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dont' ever put used ubolts on an axle. that's just foolish and asking for problems. ubolts are like $5 each and can be custom made in any length and diameter and material. just buy a new set.
 
There is nothing wrong with re-using u-bolts. ( a fable made form the aftermarket suspension companies)

Another idea is to get rid of the sway bar bracket. Are you going to keep the sway bar? Most guys that wheel get rid of it. Make sure to try it and see if you like it without.

Otherwise get new u-bolts. Don't run them without the full nut on the bolt.

hinkley
 
88woody said:
BTW, the u-bolts are just soft steel, that is why they stretch and should'nt be re-used


No they are not.

U-bolts in the size for a jeep axle are all grade 8 bolts. TS might sell some crap but if purchased for the automotive use, they will be grade 8.

The stretch because of their shape.

hinkley
 
Mark Hinkley said:
There is nothing wrong with re-using u-bolts. ( a fable made form the aftermarket suspension companies)
depends on how much wear they have seen, but for the price, why not replace them and be worry free? i can see how saving your scratch makes sense, but something cheap and plentiful like ubolts, just replace them, overtightening is common, lotsof people just crank them up way over spec which leads to stretching and ultimately failure. if you have been really good to them, then fine, reuse them, if you don't know their history, don't take the chance.
 
Great! Thanks for the info. I can afford to replace them and I will. Does anyone have a www site where I can simply order the things?

Thanks!
 
mhead said:
Great! Thanks for the info. I can afford to replace them and I will. Does anyone have a www site where I can simply order the things? Thanks!
Not positive, but you should be able to get them locally, without having to wait for shipping. The axle tubes on a Dana 44 should be 2.75" in diameter, aren't they bigger than the D35s? I just had some made for my 8.25" axle at my local spring shop. They custom made them while I waited for $6.00 apiece. 4 ubolts = $24.00. Just call around, I am sure you have more choices available in Cali than up here. When you find a place, bring in an old bolt and get them to make you some longer ones. If you want to find them online, Tomken makes them, and I have purchased stuff from them, they seem pretty good. Others can chime in here. http://www.tomken.com
Brent.

Oops, just checked tomken, they actually don't have them for the Dana 44. Sorry, my bad!
 
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Island XJ said:
depends on how much wear they have seen, but for the price, why not replace them and be worry free? i can see how saving your scratch makes sense, but something cheap and plentiful like ubolts, just replace them, overtightening is common, lotsof people just crank them up way over spec which leads to stretching and ultimately failure. if you have been really good to them, then fine, reuse them, if you don't know their history, don't take the chance.

So how many times have you, yourself seen u-bolts fail? Most if not all u-bolts fail from lack of tightness.

This is why the response from me:

Island XJ said:
dont' ever put used ubolts on an axle

Just a wrong statement. The one quoted above is much better because of your explanation. But to say NEVER (don't ever) is just SOBI( or whatever the term is).

hinkley
 
Beej said:
The axle tubes on a Dana 44 should be 2.75" in diameter, aren't they bigger than the D35s? I just had some made for my 8.25" axle at my local spring shop.
D35 = 2.62" axletubes.
D44 = 2.75" axletubes
C8.25 = 3.00" axletubes
 
Hey Yucca, from experience I have found that there are actually three different tube diameters on D35's on XJ's over the years. Don't remember the breakdown, but they kept changing the tube thickness and diameters. As it turns out the size on my rig was the same for the D35 and the D44 I replaced it with.

The only safe way to get the right size is to measure. If you don't have a set of calipers, take a tape and wrap it around the axle and measure the circumference. Then divide that number by 3.14
 
That figures...
rolleye.gif
 
old_man said:
The only safe way to get the right size is to measure. If you don't have a set of calipers, take a tape and wrap it around the axle and measure the circumference. Then divide that number by 3.14

WOW! That's like using your high school math! :D


hinkley
 
Mark Hinkley said:
But to say NEVER (don't ever) is just SOBI( or whatever the term is).

hinkley

Hinkley commits SPOBI by calling SOBI!

Stop
Putting
Out
Bogus
Information

:D :D :D
 
Mark Hinkley said:
So how many times have you, yourself seen u-bolts fail? Most if not all u-bolts fail from lack of tightness.
Brett's obviously too sensitive to respond, so I will speak for him. :D
We both saw ubolts fail on another guy's ford on the trail earlier this year. The guy said he couldn't understand why they failed; he only had 1" blocks, but he explained to us that he had torqued them to over 150lbs (!). When we looked at them they were all stretched and had sheared in the lower part of the threads. The threads looked like they had unraveled or something.
That's probably why he's taking the safe road and recommending they be changed. That, and he also just likes to hear the sound of his own voice too, maybe that's part of it!
We shouldn't be too hard on him just because he is a bit of an opinionated black and white thinker, he's very knowledgable about offroading and has built some pretty interesting stuff. So far, he's been able to help me with everything I have asked....knock on wood. ;)
B.
 
Hinkley, thats those grades you missed when you were in reform school. :jester:

I just checked and you are ahead in the voting. That must have cost you a lot of beer.
 
Thanks for the above advice. I had U bolts made locally. Cost $8.50 each one. I made a couple of mistakes which I regret so here's what I learned:

My D44 has 2.75" diameter axle tubes. My XJ has no lift or blocks although I have a pair of Rancho heavy duty leafs. Distance from the top of the tube to the top of the leaf is 2" with an additional 0.312" thickness for the retaining plate and 0.125" thickness on one U for the anti-sway plate.

I've learned that shops don't make the bolts. They just bend ones that they purchase. Bolts come straight in two inch increments.

I measured the diameter of my old U bolts on an un-threaded section. Got 0.430" so I naturally assumed that the bolts were 7/16. I ordered 16" long 7/16 threaded bolts. Trouble is that I didn't realize that the bolts are not simply threaded rods, but actually have smaller diameters over the unthreaded length with larger diameters where the threads are. Here's how my 7/16 U compared to the stock D35 (old) U:

Measurement Old D-35 New 7/16
Thread Pitch dia. 0.465 0.432
Unthreaded dia 0.430 0.405

So the 7/16 that I specified resulted in a smaller diameter, giving only about 88% the strength of the old U. I screwed up.

I'm guessing that the best U is a 1/2" which should give 1/2" thread pitch with a somewhat reduced unthreaded diameter. Should fit the retainer and anti-sway plates since these have 0.570" diameter holes. I tried screwing a 1/2 nut onto the old U. It screwed on well for the full depth of the nut but then siezed. I'm guessing that the thread on the old U is metric and close to 1/2"

The length (16") of my U gave 1.125" of thread above the tightened nuts. I could have used 14" length but I was unsure about the bend allowance I should use to compute the length of the bend so I went longer. New U have 4.5" of thread length so there is plenty of room for error on the long side.

Things worked out reasonably if I simply ignored the bend allowance and computed the effective bend radius as the radius from the center of the axle tube to the center of the U. In my case this was 2.75"/2 + (7/16)/2". I didn't take into account that the actual diameter of the U was 0.405" and not 7/16"


So I guess the best advice is to use 1/2" bolts that are 16" long, longer if there are blocks between the alxe spring perches and the leafs.
 
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