Today, I had to replace the upper shock bushings on my 04. I replaced the shocks about a month ago. I found out the hard way that the supplied upper bushings needed to be a narrower length to fit the OE mount with OE washer nut combo. So I utilized a bench grinder and removed enough poly(from both sides of bushing, slowly) to seemingly fit the non-threaded portion of the mounting stud. The finished bushings before install where smooth sanded and lubricated with wht lithium/teflon lube. I did leave them long enough to compress a bit(2-3mm) as the nut combo was torqued down though. The washer seams to encroach about 1mm on to the non threaded portion of the mounting stud.
I didn't know if I left them to long or not? should they have any compression applied in this position? When I replaced them today, I trimmed them to the open space, measured between the washer and stud base. So they seem to have no compression installed now. One of the bushings I had to use this time, was split down a seam from the orig. install. The split is about 4-6mm long, so i don't expect it to last, but In my on-line searchings I cant find a poly bushing with the (approx.) 30mm length needed for this app. Any Ideas or experiences please. Thanks
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I know that compressing urethane bushings destroys them. I don't know how much they can take. I myself have had rotten luck with them to the point where I think rubber would have been better and longer lasting.

 

Mine would attest to that but, how do they work as sway bar link bushings, spring eyelets, engine mounts and all that? All I can guess at this point is that rotational compression does this sort of bad? Thanks for the chat back. Seems we live in the same general location " poverty" he he.

 

First experience was with a damper on the tie rod of a lifted 82 F100.
Gabriel, in fact.

When they quit (went to pieces more like) it was one of the convincers to dump the project truck. Rubber is still available.

Rubber cracks over time if it dries out - but it doesn't (apparently) EXPLODE

I would prefer bushings made out of KEVLAR.

 

Yep, Kevlar it is. Explode, really describes the likes of this issue. But dump a whole project, I'm to darn stubborn . I'v removed this set of shocks acouple times to many as it stands, and will prob. have to again. Yikes. But with new or good bushings they ride real nice.

 

I got to a point where I wanted to get into Ranger trucks, for a lot of reasons. To this day I wish I had not sold ANYTHING to the clowns around me because they go halfway and scrap stuff.

But I had an engineless truck, and no desire to persue it. Other trails were in front of me so what they did was their own damned fault.

KEVLAR now - that resists a bullet hit, but gives and has friction resisting properties. It would also be a lot stiffer.

I like it, but don't know who makes anything like that for suspensions.

 

Contact Skyjacker, back in the day they replaced the front bushings no charge for me and it had been a few years since I bought the shocks... looks like the're using chinese polly these days

 

FWIW: In the application you have shown there (single shear) I would have thought the poly bushing would have sleeved on the inside at least ...

imho, If you are using poly in single shear on a shock, it would be a good idea to have it sleeved on the inside and outside.

imo, Going by the photo and your description, it sounds like you are inserting the poly into the mounting eye of the shock (outside sleeve), leaving a huge amount outside the metal ring, and squishing it down. You can't do this, it has to be fairly flush and the washers have to be almost flush against the metal ring/mount and you can't crank it down. Otherwise you will split (tear) the bushing.

There should also be an inner sleeve to ride against the stud if any part of the bushing will be outside the eye/ring of the shock mount.

 

rebocardo, And others, thanks for your replies. The upper mounting stud OD matches the ID of the bushing, and wouldn't accommodate a insert. The stud mount isn't threaded its entire length, becoming 5/8ths Smooth OD at the point of shock, bushing , stud contact( same as supplied insert for lower bushing). The amount of compression was my greatest concern upon initial assembly, I noted the almost 1/4" compression of the bushing to seat the retainer. My original reaction was to shave down the poly inserts, but was unsure as to the final compression. Looking at the bushing units that did utilize a inner sleeve I thinking that slight compression would help centrally locate the shock on the bushing. But after bushing modification, the slight (1/16th or so) amount of remaining length must have contributed to the ultimate failure.
I now have them mounted with bushings that are shaved down to match the open space left after the capture nut/washer are secured. I measured the space without the bushing/shock installed and came up with 30mm. This space doesn't leave much shoulder on the bushing but it looks to be enough to keep the shock from interfacing with the mount or washer? I guess time will tell, but as Bern mentions, there does seem to be some durometer difference in the two spare bushings I ended up using. I haven't found a vendor that swears to have a tougher poly mix yet but I'll be looking. Thanks again.

 

Yikes, It happened again. About 400 miles. I talked to a gent at a local shop today and he suggested switching to a rubber mount bushing. He added that rubber gives better isolation and that poly was is used to fight ozone v rubber problems encountered in Califonia. I dont know about the whole ozone speel but something is definatly amis with this setup. ? Did I need to burp the shocks before install? I thought I heard here, that they may need cycling or something to remove a possible air pocket? Seems after so many miles I would have felt a problem there though. This will be the fourth bushing for this shock. As mentioned above, Im sure that different manufacturers produce different quality of bushings, mind you the eight other bushing have faired well so far( steering stab. and all). Ive found Bushings from many suppliers, I just don't know who's to try next. The ones that come with the shocks are pasty red . Does black hold up better? Are clearer red units stronger. Man,O,Man, I am thinking new, new shocks.

 

> eight other bushing have faired well so far( steering stab. and all)

There is a difference between compression and shear, especially single shear on that style bushing/shock mount. Maybe something is just a bit off on that side.

> He added that rubber gives better isolation

true vs. normal poly.

> that poly was is used to fight ozone v rubber problems

true, plus, oil/salt/uv

> encountered in Califonia.

encountered everywhere.

 

Thanks reb. for the clarification. I haven't found a rubber hour glass shock bushing available, besides one for a Saab based shock( no dementions listed) . I do know , I have a need to rotate the wheels on the rig. The side with the most recent destruction does have some wedging of the tread blocks going on ( rotation past due ). I'm looking at other manufacturers bushings, and hope to find a poly set( 2pc or single unit) to try again as a replacement. Rebocardo you mention the outer / inner sleev relation to the bushing. On the upper mounts of all the rigs shocks and the inner steering stab. mnt. the bushings all had to be narrowed to fit with little-no compression. I think I mentioned the narrowing process elsewhere, But the last set that went in to the upper fronts were narrowed to not compress in the installed position. the bushing does slightly ( about 1.5mm ) extend out from the outer ring ( shock eyelet), and has a snug fit over the nonthreaded, mounting stud bushing mounting surface. This mounting surface of the stud appears to be of the same mechanical interface with the bushing as the inner collars provided for install over threaded mounting bolts used elsewhere ( all lower mounts ). In the case of the upper front mounts the narrowing of the bushings leaves less bushing extending beyond the outer ring providing greater support for the bushings that are shredding? I've found on other enthusiast sites the mention of a poor batch of poly bushings, that skyjacker admits to and maybe thats the units I have been dealing with ( even the free replacements my retailer provided x 3-2pcs (maybe thats why they where free) )? One thread mentioned the same destruction of the bushings, and the user received new bushings from skyjacker, after a call to them. With winter on the doorstep here, I hope to find a set soon to remedy this constant issue I've had. Thanks again for your reply.

 

Looking through the net catalogs Ive found that a two piece ( each side conical) bushing set is available for shock eyelets. The set i mention has a shorter combined length that may not require any mod. to fit( 1.05"v1.47"orig supplied poly), but the two piece units may not meet in center due to the approx. 30mm( 1.18") mounting location ? Prothane prt#19-915 blk, as it would be, seems to spec out, to slightly apply more preasure to the outer (inside) surface of the shock eyelet, but being two pcs may reduce torshinal shear in this app.? Sorry, I'm ratling on this one.