burkett.j

Thanks for the help everyone. I'll avoid the add-a-leaf and just go ahead for the new springs when I can get the money together.

RocketMouse

Another thing to do before starting the project is once you order the parts you will need.... start daily giving the bolts a good shot of PB or something over a few days time to help. Also... do yourself a favor and order new U-bolts too. You don't want to reuse old torqued bolts. They are cheap to replace too.
I agree... last April I pulled my 21 year old nearly collapsed rear leaves off and replaced them with a pair of full Crown 755lb HD ones and couldn't be happier. Nearly a year now and they are settled and working perfect. If yours were nearly flat like mine were... you'll actually notice a decent little lift out of the HD ones. And definitely go with a new bushing set, they are dirt cheap. New springs, why use old worn out crap back on them? You can reuse the old stock shackles if they're in good shape, just put new bushings in. I think it only cost like 10-15 bucks a side... well worth it IMHO. Got a great deal on them from Quadratec at the time.
Just FYI...the HD ones do ride a little stiffer than others and definitely more than stock...but I've never noticed mine bouncing around or an overly rough ride.

Dave51

You could get the bolt set from Tubur. They're good quality and at a good price. Just tell him to package them well.

Also you're going to need some sort of gimmick to get the bushing in the springs. If you've got -0- tools you're going to need some stuff. Either Google or ask for ideas (don't ask me tho, I've got the 20 ton hydraulic press).

third coast

I looked at those but they are not at all similar to OEM suspension bolts. His bolts as shown in the photo in the For Sale section of this forum are not flange head bolts, the head is not as beefy and they do not have the factory locking material applied to the threads. The threads do not appear to have the reduced diameter lead-in or flutes at the first few threads that I expect would help get the bolt started correctly and clear any rust and debris from the nut inside the frame. I would hate to get that far and have the non OEM bolt screw up the inaccessible nut that is welded into the frame. The Chrysler bolts are made in the USA so I don't wonder about quality and material properties like I would with what might be a made in "wherever the cheapest place is" bolt. For critical suspension bolts I don't mind paying more for the correct spec part. Chrysler put a lot of design features into that bolt for a reason - good enough for me.

Photo is an original bolt I removed from my '91 XJ so you will not see the locking material. Wish I had taken a photo of a new one.

Dave51

Dave51

I know what you mean. I have an 0331 head that I got from...

Oh wait...

Dave51

Yeah here's the bolt I took out of my 2000:



OK so maybe it was the bushing that was missing "design features", but somehow I can't help thinking their primary concern was cost...

Dave51

And truth be told, my transaction with Tubur wasn't all that smooth. The bolts were placed loose in a Priority Mail Box, and because of their weight rattling around in there the the busted box open. By the time I got it 4 of the 6 bolts were missing. So he says

So I'm like "I have to go thru that cause you didn't pack the stuff properly?" Well, whatever, I eventually got my money from the Post Office (yeah that happens overnight).

At any rate, IMO the bolts are OK.

TrailerTrash

I think that all the thought went into what bolts to use. They made a good choice. Then they had a party to celebrate the decision and they all got ****faced. Then the next morning they were all hungover and designed the weld-a-nut-inside-of-a-pocket-and-weld-the-pocket-to-the-frame nightmare.

My transaction with Tubur was excellent. Bought a master kit and used most of it installing my lift.

third coast

I am afraid this is might turn into a bolt thread. My fault - engineering background so I can't help it. I know Dave is interested and others in the future might learn something but for those that are not interested feel free to skip this post. It is long and rather technical. I agree that the hidden welded nuts are not great when we work on these after rust has set in but that setup is there, we can’t practically do anything about it and we are talking about bolts now anyway. We can do something about the replacement bolt we use.

The more I thought about these bolts the more important I found the OEM design to be. As I mentioned in my earlier post this is not a run of the mill inexpensive bolt. Chrysler engineers selected it for good reasons. I am sure the cost analyst team ask why a cheaper bolt couldn’t be used. Beyond flange bolts not requiring washers that would be another part number to procure/stock and that can go missing during assembly a flange head bolt has several distinct advantages. Keep in mind that these bolts see high loads in use. Maintaining proper torque on the bolt is essential to ensure various parts of the bolted joint stay clamped together and distribute loads properly to ensure long life of the components and safe driving. Lets look at this:

* The flange head of the OEM bolt is sturdier than a standard hex cap screw discussed in earlier posts, thus it can take more abuse from the high loads of this application.

* Standard washers are typically a softer material than the bolt and will deform under the high compressive stresses they must maintain. Under high loads they will dish or indent, significantly reducing the clamp force. Flange bolts do not have this problem as the washer is effectively part of the bolt head and has the same strength.

* If someone chooses to leave the washer out entirely this is much worse. Using a plain hex head bolt will increase the pressure under the bolt head significantly and potentially beyond what the steel can support, resulting in deforming the surface and result in loss of clamp load with time. Lack of a washer on a cheap bolt can also result in the fillet, or radius between bolt body and head, being heavily loaded where it rests on the sheet metal of the spring box. This can excessively fatigue the bolt to the point of failure.

* Tightening torque values were determined with the OEM bolt. Substituting bolts of a different type and finish, or using washers, will result in different torque-tension characteristics that may result in problems down the road. (A decent percentage of the applied torque is absorbed at the bolt head and threads in the nut, thus changing the actual clamp load)

* The large clearance hole in the washer can result in eccentric loading, or loading the bolt head on a smaller section of the washer and metal below it. High localized loads can distort the materials, resulting in reduced clamp load.

* Note the OEM bolt in my photo in post 19 has a larger diameter near the head. I expect this is to pilot the bolt snugly where it goes through the body spring box to better accommodate the loads.

* The OEM bolt has a reduced lead-in diameter at the end, making it easier to get it started properly in the nut.

* Flutes are cut into the first few threads, potentially to help clear debris in the nut from the manufacturing process, including paint and undercoating that could affect clamp load. For a vehicle with many years and miles that feature could help clear dirt and rust from the hidden nut.

* An aftermarket blue type of thread locker could be applied prior to assembly to help keep things tight if using bolts without the factory applied material. In my case I coated the inside of the spring bushings metal sleeve with anti-seize to help prevent the issue Dave had with the bolt rusted to the sleeve. In the case of the welded in hidden nuts there would be no surefire way to get the bolt through the anti-seize coated sleeve without scraping off the thread locker material and heavily contaminating it with anti-seize. I doubt it would be effective after that.

You can see there is a lot going on with that bolt. The guy selling leaf spring bolt sets said they are the correct specifications. NO WAY!!!. I expect it is an uninformed error on his part but he should not be selling something that could be safety critical without validating the parts ability to meet OEM requirements. One failure of the suspension bolts he sells as "correct specifications" and someone gets hurt or hurts someone it will not end well for anyone.

Dave51

Well, actually not a bad place for it.

I have 2 comments, both related to

The thing about the flange vs. washers is irrelevant. There is zero none nada -0- zip naught lateral pressure involved here. The springs don't go sideways and even if they did the pressure would be absorbed by the bracket.

What does happen though is that there is plenty of rotational strain placed on the bolt, so if you don't slather it in thread locker it will loosen up. I initially didn't put threadlocker on cause I was doing some fitting or something (forgot why) but the bolt loosened up in just a few days.

Dave51

But this is an interesting thought. If the bolt is sloppy in that opening perhaps the hole in the bracket could get enlarged, or at the least get a nuisance click (I did have nuisance clicks, don't know exactly where from. Disappeared after adjusting everything with the 48" breaker bar). Would need to mic up OEM vs tubur bolts to really analyze this tho.

third coast

Good - it looks like I have encouraged some technical thought on this subject. Dave, as usual, has some good points. The comment about no "lateral pressure" is probably mostly correct relative to side loads due to spring movement. There is bound to be some but we can ignore that for now. By 'lateral pressure' I believe you are thinking about tension on the bolt, or the load trying to stretch the bolt and separate the components. Most bolted systems rely on the preload, or tension, of the bolt to work properly. This preload is achieved by torquing the bolt. XJ suspension bolts are specified to be torqued to somewhere between 95 ft-lb to 115 ft-lb depending on the location and the spec you are looking at. That is fairly high - as high or higher than lug nut torque. Torquing the bolt puts the bolt in tension and the components being attached in compression. This 'lateral pressure' or bolt tension is essential for the joint to remain tightly clamped under all conditions, as I believe is the design intent on the leaf spring and control arm. Without the preload on the bolt the loads and resulting issues increase significantly. Any deformation of washers (they can exhibit plastic deformation) and the spring box will result in relieving the tension on the bolt, or a bolt and nut that are no longer tight. That is not what we want.

More later. I want to think more about this setup but it seems that the bolted system of the leaf spring components is a rather complex system of loads where the design intent needs to be respected for proper performance and safety.

third coast

I did run across info that mentioned that spring clunking, snapping and popping can be the result of worn bushing or bolts allowing spring end play, worn or broken spring shackles, or loose U bolts allowing excessive spring movement. I expect inadequate spring bolt torque along with an opened up through hole in the spring eye mount would present similar symptoms as worn bushings or bolts. Torquing everything seemed to cure the noise in your case.

third coast

Dave: Looking at my old bolts I noticed something interesting. You bushings may have been degraded to the point they were letting water in but loss of bolt preload may have been a contributing factor. If the bushing is in good condition and everything is clamped together properly water should not be able to get into the bushing sleeve. See my photo and post here: https://www.cherokeeforum.com/f46/19...1/#post3596415