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Old 01-26-2018, 09:42 AM   #1
Mr Bear
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Poly Suspension Bushings Notes

So, spent the last two weekends working on the 87 GMC Jimmy getting all the suspension work done.

Previous effort included checking the frame horn for cracks and installing a reman power steering box with a borgeson extreme duty intermediate shaft.

Ball joints were fine so was limited to replacing the tie rod ends with moog and the drag link ends as well. Drag link is visually parallel to the ground but shortly ill have an angle finder and can check it for sure. Also installed a new Rancho steering stabilizer shock. No slop in the tilt steer, realigned with slightly increased toe in, about 3/8". Removed the super large 11.5x32 tires and replaced then with factory size.....speedo now correct, ride more stable, plenty of body roll but at least it mostly go's where I aim it.

Last weekend, I used the energy suspension shackle bushing kit for the rear of the front leaves. A couple findings of note. Buy more grease....I used both the energy grease and dielectric grease. The bushings fit snugly into the shackle and frame holes. The energy sleeves require a clamp or bolt and nut to press them thru the poly bushings once the bushings are installed on the truck. Also, note the energy set with its new sleeve is 3.25" wide. this is .25" narrower than the inside width of the shackle with the factory bushings and sleeves. However, there was no issue with the install as the reduced width works fine with my original 2 leaf spring pack. I have yet to install the front spring eye poly bushings, a much bigger job and I'm not yet ready to spend the time drilling and pressing out the factory metal sleeved bushings. Went for a weeks driving, 140 miles daily round trip for work and overall, much improved but still requires a relaxed posture to drive it straight. Very much better on rough single lane country roads. Stiff arm it though and I find myself adding to the body roll and darting left right, especially at night with my aging eyes. Ride is generally a bit firmer/more precise. Hardest part of the shackle bushing job was clearance from my PS side dual exhaust head pipe.....once the frame shackle bolt was out, I had to reverse it, nut inside, to put the bolt back in.

Came home last night and decided to loosen the nuts on the front sway bar ends and install prothane bushing set on it. Fortunately its a southern truck, and a jack on the 1 1/8" wrench easily broke the end bolts free. Again, with the prothane, buy more grease.....I used prothane and dielectric grease. The prothane end bushings were an easy sip fit into the sway bar eyes and the metal sleeve a firm hand push fit into the poly bushings. I removed the sway bar, truck on the ground, level. As hoped, there was no torque on the bar and once broken loose, the end bolts simply backed out by hand. Given I felt no torque on the bar with weight on the suspension, I am satisfied my original 2 pack front leaves are in pretty good shape, no significant sag and the negative arch with weight on must be by design. I have to assume these springs are flat or only slightly positively arched when removed. The prothane bushings over the bar are nicely made, split for install and grooved to hold grease. I installed the same as the egg shaped factory rubbers, split facing the rear of the truck. They fit the clamps and 1.25" bar nicely. Hardest part of this job was breaking the end bolts loose and getting a wrench on to the back side of the upper clamp nuts. I'm looking forward to riding for a week to see what improvements are noticed.

About all I have left to do is get after those front spring eye bushings and sleeves and get to lowes for an angle finder and check my caster. but looking at the axle I can't imagine the angle is less than the factory spec of 8 +/- 1 for the 87 Jimmys.

I know its always going to wander a bit, being short bed, solid axle, elliptically spring and heavy, but the work does make it much easier to drive relaxed. 65 mph on the highway, Beast rolls dead straight hands off the wheel and at lower speeds on rough country roads, pretty much the same straight line performance.
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Old 01-27-2018, 02:54 AM   #2
68Timber
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Re: Poly Suspension Bushings Notes

Good write up. Do you have any problems with the steering wheel not returning to center on it's own after installing the Rancho steering stabilizer? I installed their single-shock model on a 76 K5 I had years back and had that problem. When I replaced the front spring and shackle bushings on my 85 a few years ago, the fronts were egged out so bad they couldn't do their job anymore. Much improved ride after that. I still need to do the front sway bar and rear spring and shackle bushings, but you can definitely feel a big ride improvement when you start replacing those bushings. You bought the white and blue Jimmy, right? Pics?
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Old 01-27-2018, 08:13 AM   #3
Mr Bear
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Re: Poly Suspension Bushings Notes

Yes, the white one with the blue rhino liner on the bottom.

I had noticed, somewhere after replacing the steering stabilizer and before replacing the overly large 11.50 Goodrich TA tires that Beast needed a touch of help returning from a turn....I'd say it returns 90% by itself and the last bit is by hand. Id not attributed that to the rancho steering stabilizer but I've not checked caster/camber yet either. (Probably check caster today, camber not so much, there's seemingly not much adjustment/changes one can make there, at least not easily.) Is this a common issue with the rancho shock? (was thinking of going to duals since the power steering is so powerful, I was thinking two might be the ticket to dumb it down a bit. Would be nice if the power steering could be dual phase, power in the parking lot and lots less power at speed)

I have some more driving to do, (an advantage of a 140 mile daily round trip to work, by the weekend I have a great feel for whats changed and or needs further work).

But, a 50 mile drive yesterday was amazing. Good road and bad, the poly bushings on the sway bar were the most significant positive improvement to date. I suppose its a combination and the results were so noticeable because nothing else in the front steering and suspension is worn, but WOW! So much so that i'd have to say, the poly sway bar bushings give a positive feel that is greater than the sum of all the other suspension and steering work done before.

Beast suddenly became easy to drive. Mostly one handed and very relaxing. The body roll feels completely different, roll is not as deep or sudden....as such, I don't feel I need to input corrections at the wheel. All of a sudden I can sip coffee on a rough road, talk to the wife in turns and except when scratching my butt, I pretty much stay in my own lane!
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Old 01-27-2018, 03:00 PM   #4
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Re: Poly Suspension Bushings Notes

Caster is on the money, both sides at 9 degrees. Drag link is perfectly parallel to the ground and the camber is 0 degrees on both sides. Nothing more to do but drive.
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Old 01-27-2018, 09:21 PM   #5
68Timber
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Re: Poly Suspension Bushings Notes

I think the Rancho stabilizer is too big and dual stabilizers might make it worse, and I'm basing that guess on them being made for much larger tires on lifted vehicles. If you have 90% return to center, that's great compared to the 76 I had.

I have to replace my steering box shortly, it's old and worn with lots of play. I thought about doing the Jeep XJ steering shaft upgrade but decided to replace the rag joint with a new one instead. Based on your review I'm going to do the sway bar bushings at the same time. Hopefully that'll cure my loose wheel.
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Old 01-29-2018, 11:23 AM   #6
Mr Bear
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Re: Poly Suspension Bushings Notes

Good luck. Ride in this morning was pretty good. I have more trouble with seeing in the dark (oncoming glare) than with the steering now. As for rag joint, spent my Christmas money and just went with the Borgeson extreme duty (no rag joint). Figgered the double u joints would probably outlast the rags that are available. None of the replacements seem to be as good as the originals.....

As for the poly bushings, I am amazed at the difference from worn rubber on the sway bar to poly. It comes at the end of a lot of front end repairs so I know its working with good parts....but as I said, the difference is more noticeable than all the other work that came first.
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Old 01-29-2018, 11:41 AM   #7
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Re: Poly Suspension Bushings Notes

When I did the Prothane bushings on my shackles, I modified the urethane bushings (slotted the insides) and drilled and installed grease fittings in my shackles. I had heard nightmare stories of the squeaking that can occur over time and decided to be able to grease the bushing occasionally from the outside.

It's just a test because I do not know how urethane will hold up with automotive grease but it's been more than 2 years and they seem fine.
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Old 01-29-2018, 12:31 PM   #8
Mr Bear
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Re: Poly Suspension Bushings Notes

Long time ago, about when poly was just coming on the market, or at least just long ago, I put PST poly on the front and rear of an impala. As I recall, no squeaking and no worries. Made that old floater feel a bit more precise too.
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Old 01-29-2018, 02:35 PM   #9
68Timber
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Re: Poly Suspension Bushings Notes

Do you have a link to the Borgeson joint you used?

I've always used the grease that comes with Energy Suspension bushings, never had any squeaks.
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