Gap between leaf spring and hanger

[lpukas2]

What is everyone concessive on this? The related parts are Dorman leaf springs 97-400 and Crown J8127712 brackets. It appears that the bushings in the leaf spring are too narrow by 1/4". Ignore the crappy bracket from Crown, that will be addressed. From what I gather, pretty much all new leaf springs for the older vehicles are around 1/4" too narrow.

I do have a set of Omix 18271.05 coming today.

Just run washers?

Swap the brackets to custom 2.75 wide ones. (Trying to keep everything somewhat OEM)

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[tgreese]

Add washers to fill the gap.

Usually Crown is better stuff than Omix.

[Stuka]

I am assuming this is the rear hanger for the front spring. However, in the photo that looks like the front eye of the spring. The rear eye of the front spring should be much larger, and the bushing should be wider. There is often some gap there, as newer bushings arent as wide. But its a pretty small different. For both of my FSJs one washer filled the gap.

The stock springs are 2.5" wide. 2.75" wide hangers are going to be too wide. The stock hanger is a bit wider than 2.5 as the rear bushing from the factory was a bit wider than the spring for better NVH.

[lpukas2]

It took me a few to realize what you are saying Stuka. I did not realize the front eyelet is a smaller diameter than the rear. I also pulled up the overall width of the bushing, the front is narrower than the rear.

I will fit the bracket to the rear of the spring and see how it looks (2 more brackets should have shown up today). If it's good, it looks like I can replace the front bushing with P/N RB-140

I plan on using these brackets for both the front and back.

Front - RB-85 1.25 OD 9/16 ID overall length of 2.6875
Rear - RB-170 1.5 OD 9/16ID overall length of 2.875

RB-140 - 1.25 OD 9/16 ID overall length of 2.875

[sierrablue]

I'd recommend poly bushings over the rubber actually. Better feedback, WAAAAAAAAAY easier to install, and it allows the suspension to actually pivot, instead of just twisting the rubber into a pretzel and then coming back. Should last longer too. That hanger is going to be too wide for either end.

Also your spine doesn't like the frequency rubber puts out with vibrations. Not as big of a deal with a spring seat and stuff there (vs a tractor seat from the '20s, where they discovered it), but still something to consider.

[Yeller]

Hmmmm..... I spend a lot of time and effort changing from poly to rubber to clean up NHV and squeaks. Poly is typically denser and transfers vibrations more. If its an option I always choose rubber over poly.

[Stuka]

Hmmmm..... I spend a lot of time and effort changing from poly to rubber to clean up NHV and squeaks. Poly is typically denser and transfers vibrations more. If its an option I always choose rubber over poly.

Yeah, the squeaks from poly bushings drive me nuts. No matter how much you grease them, they squeak. They are great for auto cross and road racing, as they tighten things up. And offroad they will allow the spring to rotate better. But the NVH they produce is not great for vehicle being used on the street.

[lpukas2]

Well, it looks like the RB-140 - 1.25 OD 9/16 ID overall length of 2.875 will work. Going to use washers to get everything mocked up. Going to stick with the rubber bushings for now.

On another note: How does the placement of the spring look? Currently the spring pin is 1" forward of where it originally was. I am a bit concerned with having the axle forward 1", not that there is much room to play with it. Axle will be placed SOA for now and will see what the weight of the drive train does to the springs.

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[sierrablue]

IMO these things already have springs that are PLENTY soft--if it's stock and everything works properly you've got to be looking for NVH. At least on the Wags--I'm sure the trucks are a little harsher due to the stiffer rear springs.

I put poly bushings up front and the old rubber ones in the back still squeak far more loudly than the front ones...not even greaseable bolts. You can feel that the suspension moves much better and gives better feedback with them--without being more harsh.

But I'm weird. I like a stiffer suspension and prefer feedback and a solid, tight driving feel, and as long as I'm not being bucked all over the place (aka everything moves smoothly), over something that floats along like a boat and doesn't feel bumps.

Looks like lift springs (in which case NVH is out the window anyway imo, on a leaf spring setup)--I would just trust that the manufacturer changed it due to the lifted geometry, unless you run into issues with it hitting the steering or something.

[Stuka]

IMO these things already have springs that are PLENTY soft--if it's stock and everything works properly you've got to be looking for NVH. At least on the Wags--I'm sure the trucks are a little harsher due to the stiffer rear springs.

I put poly bushings up front and the old rubber ones in the back still squeak far more loudly than the front ones...not even greaseable bolts. You can feel that the suspension moves much better and gives better feedback with them--without being more harsh.

The rubber bushings can't squeak. They are emulsified to the spring and the center, so they cannot move at all (Unless the rubber is torn of course). If the rear squeaks, its something else. Poly bushings squeak like crazy in every vehicle I have dealt with. Its the reason they are often greaseable, but its the only way to try and make them squeak less.

NVH isn't really about being stiff. Its about minor noise, vibrations, and harmonics coming into the chassis/cabin from the rotating assemblies. You can have super soft springs, and still get bad NVH.

Not saying you can't like poly bushings, plenty of people do, and they do have some advantages. They just arent for everybody.

[Stuka]

Well, it looks like the RB-140 - 1.25 OD 9/16 ID overall length of 2.875 will work. Going to use washers to get everything mocked up. Going to stick with the rubber bushings for now.

On another note: How does the placement of the spring look? Currently the spring pin is 1" forward of where it originally was. I am a bit concerned with having the axle forward 1", not that there is much room to play with it. Axle will be placed SOA for now and will see what the weight of the drive train does to the springs.

image_50457089.jpg

Hmm, If you measure spring eye to center pin for both halves of the spring, what do you end up with? Those springs (97-400) are supposed to be 74-91 FSJ specific. The center pin should be offset, and typically the springs have "front" painted on them so as to not put them in backwards.

The front spring hanger looks to be in the right place. For reference, another member did this same thing on his J-Truck, lots of photos here. Though its worth noting he also did a shackle reversal, so there is some difference there. Though the spring hanger locations should be the same. viewtopic.php?t=18528

[SJTD]

I'm drawing a blank, what's NVH? In my world it was non-volatile hydrocarbons.

I read a lot about urethane bushings squeaking but the ones on my CJ never have. Always wondered about that. Prolly will start now.

What I don't like about them is they rely on the flanges for lateral support and there's usually not a lot of thickness there. My son's Toe-yota solid axle kit's bushings don't even touch in the middle nor did they come with sleeves to keep one from overtightening the bolts, squeezing the shackles together and crushing the bushings. Also allows bending the frame mount.

Granted that's not the fault of the urethane.

Maybe they're required when you have huge travel but gimme good ole rubber.

[Yeller]

I'm drawing a blank, what's NVH? In my world it was non-volatile hydrocarbons.

In automotive engineering, NHV = Noise - Harshness - Vibration

We all have different backgrounds and its surprising how often acronyms crossover to mean entirely different things in different industires.

[SJTD]

You had me thinking I had goofed up but in in the earlier posts they were using NVH rather than NHV.

Not that I knew what NHV meant either.

[sierrablue]

IMO these things already have springs that are PLENTY soft--if it's stock and everything works properly you've got to be looking for NVH. At least on the Wags--I'm sure the trucks are a little harsher due to the stiffer rear springs.

I put poly bushings up front and the old rubber ones in the back still squeak far more loudly than the front ones...not even greaseable bolts. You can feel that the suspension moves much better and gives better feedback with them--without being more harsh.

The rubber bushings can't squeak. They are emulsified to the spring and the center, so they cannot move at all (Unless the rubber is torn of course). If the rear squeaks, its something else. Poly bushings squeak like crazy in every vehicle I have dealt with. Its the reason they are often greaseable, but its the only way to try and make them squeak less.

NVH isn't really about being stiff. Its about minor noise, vibrations, and harmonics coming into the chassis/cabin from the rotating assemblies. You can have super soft springs, and still get bad NVH.

Not saying you can't like poly bushings, plenty of people do, and they do have some advantages. They just arent for everybody.

I've heard dried old rubber squeak before, unbroken. The poly in my dad's Mustang and in mine has never really squeaked, certainly not louder than anything else. Wouldn't stiff fall into the harshness category? And I mean super soft springs are only gonna fix harshness pf the three.

I appreciate it. I just haven't seen anything wrong with them and given the function advantages I personally don't see using rubber. Just my opinion tho.