ISO-K Bushings - Energy Suspension VS Prothane

[Montclaire]

Ok, there seem to be two main manufacturers of poly iso-k bushings, Energy Suspension and Prothane. I just bought the ES kit but haven't installed it yet. It looks like the bushings have an integral steel support, and they are all round, although two out of eight halves are taller than the others. Summit is listing these for $112.26.

https://www.summitracing.com/parts/ens-5-4111r

The other kit is from prothane, with what look to be two major differences. One, there does not appear to be a reinforcement sleeve in the center of the bushing halves. And two, the bottoms are square-sided, like the originals. The price is much lower at $62.37.

https://www.summitracing.com/parts/ptp-4-101

So the question is, has anyone installed either kit? Did you have issues with the Energy Suspension bushings due to the round (as opposed to oblong) shape? If I knew about the prothane kit before I ordered, I probably would have gone for the cost savings.

Thanks

 

[idrivemopar]

I am using the prothane kit, no issues.

 

[Montclaire]

I'm guessing you would not need the plate with the ES bushings since they have the metal sleeve?

 

[rumblefish360]

The plate? One on top, one underneath.

https://static.summitracing.com/global/images/instructions/ENS-17262.pdf

 

[Nacho-RT74]

He meant the one on bottom of the top section, with the oval bushing. The ES one got that bushing BUT not the plate on flat portion like original does.

original oval bushings are made with the flat portion in one piece

 

[Montclaire]

He meant the one on bottom of the top section

Right, if I remember correctly, that positively locates the bushing stack in the k-member. It looks like the integral sleeve on the ES units would perform the same task, while you would need to reuse your original plate with the prothane bushings (nothing there to hold it but poly).

 

[Montclaire]

I'm starting to wish I just waited for a set of the DC cast iron ones.

 

[idrivemopar]

Are you talking about this metal sleeve? If I remember correctly, mine were the same size as the bushing, so they wouldn't fit even if I wanted to use them, plus as you can see by the photo they were completely rusted out. I didn't use anything, should I have ?

 

[Montclaire]

I didn't use anything, should I have ?

Well, if you think about it, what's to keep the k-member from shifting and slicing through the poly? The only thing to stop it would be the tube insert that the bolt passes through. On the ES bushings, the oblong sleeve SHOULD take the place of the factory plate, and guard against that happening, shouldn't it?

 

[Nacho-RT74]

I don't think thats too critical on a poly mount which is harder than the rubber piece

 

[rumblefish360]

OH! I see. I don’t remember those being on my later year Magnum.
I picked up the by durometer (sp?) parts from Mopar years back.

 

[idrivemopar]

I'm not too worried about it as Nacho mentioned, its a harder material than the original rubber. Also, when I had my k-frame out, I smoothed out the openings for the bushings, plus I had it powder coated, so it shouldn't be too rough on the bushings.

 

[Montclaire]

Might want to pull one after 5000 miles or so and see how it's holding up.

 

[Nacho-RT74]

my assemblies were so destroyed than I had to make new the internal square bushing/spacer too. My uncle works with iron and stuff and he made allmost exact copies to the originals, welded to also new big washers on top. He even got me those gold finished to prevent rust, like the originals ( dunno how do you call that finish job in english... just like the midland ross brake boosters )

 

[mopar73dge]

I used A Just Suspension iso bushing kit back in 2002, you need to use the shims and tube . The original had a square tube which was molded into one rubber bushing. Use washers since they are loose now. not molded. The tech manual suggested using the same amount of shims if they were originally present. After 16000 miles they are holding just fine, torque to 250 FT LBs min. Every year I spray silicone WD 40 into the hole of the frame section above the rear bushing area to keep moisture and rust away from the weld nut, if I ever want to remove them they will come out easier. It will keep the 45 year plus box area from rusting any further. I have one rubber original used bushing in excellent original shape with the molded washer I would sell. For some reason the rubber dougnut held up and did not rot all the other pieces rotted The front parts were the best shape.

 

[Nacho-RT74]

yes, fronts are allways better shape because the wheels don't splash on them like the rear ones

 

[69bfan]

I am hoping to have an OE style available by mid January. We have finished up the metal work and made the molds for the rubber slugs. We will hopefully be testing them before Christmas to insure that they fit and function as the originals.

 

[nstyle73]

I used a set similar to the Prothane bushings from Just Suspension back in 2004. I think this would have been when the poly stuff was just really taking off. I pulled the K-Frame last year and there were no issues. The bushings barely looked used, that was only about 15K miles though.

 

[Montclaire]

While we are on the subject, I'm surprised that the k-member mounts get all of the attention, while you never hear about the torsion bar crossmember bushings. I have to think there is a ton of slop to be eliminated there as well?

 

[idrivemopar]

I didn't notice any slop in the torsion bar cross member mounts, but they were rubber and certainly squished out like the k-frame were. I replaced those with urethane bushings, and also grade 8 bolts, as the old bolts were fatigued and stretched.