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Changed to poly body mounts

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dyeager535, Jan 21, 2003.

  1. dyeager535

    dyeager535 1 ton status Premium Member

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    Went to the shop to pick up my cam and lifters, couldn't stand to wait, so bought poly body and engine mounts.

    Started at 3pm on Sturday, "wrapped up" just after midnight.

    Ran into just a few problems. I'm *guessing* from reading previous posts, that the rear most body mount is different between the years. There was no way in heck that I could have swapped the mounts without pulling the tank, and thats what took so long..couldn't siphon the gas (nothing to put it in) and it was about 25 gallons worth.

    Anyways, the instructions say to discard the rear bushing "holder" which doubles as the nuts for the bumper supports on either corner. I just cut the top of that mount off, so that the bushing could sit on it, and kind of hold it in place. I can't imagine trying to remove those two nuts they want you to use, on either side, through the frame.

    Of course, the upper core support bushings that came from a donor truck were already poly (good waste of time pulling those lol) so I ended up with two spares. I also spent a lot of time drilling two holes in each "cup" washer that holds the lower bushing in place on both mounts, since they hold water and rust everything so bad. Cheap drill bits don't last long.

    Other than pulling the tank, the most difficult thing was jacking the body up high enough to remove the old mounts. Since the suspension lifts the truck up as you try and remove the body weight, it takes a lot of wood blocks.

    Instructions were easy enough to follow, although I didn't quite grasp that you had to strip the rubber from the front body mounts and re-use the metal. Nowhere was there mention that the tank would be in the way for that back mount "bracket". It was SO close to coming out of the small hole at the back of the frame (where the rear crossmember attaches to either frame rail) but it just wouldn't fit.

    Went out and tried to find something to twist the truck up on, but living in the city sucks for that. Finally found a small pile of broken concrete to pull a wheel up on, and at least so far, all the creaks and other noises the body used to make, are gone.
     
  2. imiceman44

    imiceman44 1 ton status

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    Hey dorian a trick when you don't want the springs to unload when you raise the body is to put a chain around the frame and the axle when it's loaded, that way the chain will hold frame down when you raise the body.
    We use the same trick with soft springs when we want to change a tire and the hi lift doesn't go high enough to lift the tire off the gound.
    /forums/images/graemlins/thumb.gif
     
  3. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    I've done the chain around the axle-to-frame trick before... works like a charm for trucks hitting 900+ on the RTI ramp! /forums/images/graemlins/grin.gif

    -Dan
     
  4. reddog64

    reddog64 1/2 ton status

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    yeah poly mounts are sweet.. did mine with the body lift.. big difference in body roll...

    I got my rear ones in on the 74.. a bit tight on the fingers.. but after a few brres i got them in there.. had to buy a new wrench.. couldnt get the old one out... it fell out somewhere between here and the farm though... haha /forums/images/graemlins/rotfl.gif
     
  5. Sandman

    Sandman 3/4 ton status Author

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    I've got my new body mounts in a box waiting to go on. Maybe I can get to it next week. /forums/images/graemlins/grin.gif
     
  6. 90K5

    90K5 1/2 ton status

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    Dorian, do they squeak a lot, or at all? Thats the only thing i dont like about poly stuff...
     
  7. Sidepipes

    Sidepipes 1/2 ton status

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    90K5, I have poly everything(a-arms,swaybar, body, trailing arms, control arms) in my vette, no squeaks at all. Just properly lube them during installation and they are no problem. They are about 5 years old now, maybe 15,00 miles on them and they still look brand new
     
  8. Sandman

    Sandman 3/4 ton status Author

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    I put those poly bushings in the rear control arms of my '71 SS Chevelle and I could not believe the difference it made in handling! I plan on putting poly everywhere now.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Poly body mounts shouldn't EVER squeak.

    If they squeak, that means the body is sliding around, and no matter what material it is, theres a problem.

    So...no, mine don't squeak.

    Contrary to some, I will NOT use poly for anything other than swaybar endlinks, body mounts, engine or tranny mounts. Poly binds, thats why it squeaks, and if it binds, its not good for suspension. You can lube it to "fix" the problem temporarily, but I don't want to be lubing bushings that didn't need lube from the factory.

    Trucks probably have less of a problem with poly in suspension components due to the sheer weight, and the fact that handling isn't very good anyways, but on a vehicle (like a performance car) that you can feel every little handling charecteristic in, you don't want something that binds.
     
  10. Sidepipes

    Sidepipes 1/2 ton status

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    Dorian I'm going to have to call you on that one.

    The reason Poly bushings are used in suspension is because of less deflection than in an equivilant rubber. Yes all out race applications use aluminum bushings but that is where ride quality does not matter. Poly is a good alternative to someone who wants a stiffer suspension yet doesn't want all out race parts.
    If your bushings are "binding, It means they are not operating correctly or they are moving too much. the outer and inner surfaces of the bushing should not move!!!! the differences in movement between the outer and inner races of the bushings should be absorbed by the bushing........ thats what they were designed for!

    In cases of extreme articulation or weight, I can see a poly bushing being a detriment.... they are stiffer and are more likely to split than the equivilent rubber bushing. But in performance vehicles they are a good compramise between rubber and aluminum.
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    If poly squeaks without lube, something is moving, and something is binding up. It's that simple. It doesn't matter WHATS binding, but any time you have binding, you have resistance to travel. (when dealing with bushings) I've known people to install poly on rear control arms, and end up with 2" of variation in rear ride height. Why don't GM apps. squeak?

    There have been posts on here about poly "coming apart" and it sounds to me like it's either A) from too much weight, or B) too much weight coupled with poly's resistance to "twisting". It's so stiff, it crumbles and cracks, instead of tearing like stock bushings do when they get old.

    Now, poly isn't a bad COMPROMISE between rubber and something like del-a-lums for people that don't want to spend tons for bushings. It's just that its not ideal. My whole post was really as it relates to trucks: these trucks handle like crap, and no matter how much poly or special bushings you put on it, it will NEVER handle like a car. The point being that I think poly on a truck in suspension applications is pretty pointless...you'll be VERY hard pressed to tell the difference between poly and *GOOD* rubber bushings in a truck. And if you can't tell the difference, and GM rubber lasts for 20+ years, why use something that is going to potentially annoy the hell out of you?

    I realize the importance of "stiffer" bushings, and so did GM. Thats why some apps used different rubber compound bushings. (Base Camaro vs 1LE for instance)
     
  12. imiceman44

    imiceman44 1 ton status

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    I second everything Dorian says here and I had the same response in a similar thread about a month ago.
    If you want articulation poly is not your thing.
    It could be good on the snow or the dunes but not on rocks where your axles are going to twist and that will twist the springs not just up and down movement.
    But if you are not convinced from our experience then by all means try them yourself.
    /forums/images/graemlins/deal.gif
     
  13. 90K5

    90K5 1/2 ton status

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    Thanks everyone, i'm probably going to do this soon then. I asked because there are some poly shackle bushings on the rear springs and they squeak real bad and drive me crazy
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    I've got poly body bushings on my car already, but it's not driveable yet. Did the swaybar endlinks, and they worked fine.

    I've never heard of anyone complaining of the poly car body mounts either, and I know a fair amount of people that run them.
     
  15. Sidepipes

    Sidepipes 1/2 ton status

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    I think if your bushings are binding you are asking too much of the bushing...I personnally don't think a poly bushing is good on a 4X4 in which you want articulation. By Design Poly restricts movement better than rubber which causes the bushing to move in its housing..... a bushing is not supposed to move in its housing. The problem is not the bushing binding.... the real problem is why does it bind.

    The reason I answered this was to the last line in your second post where you stated "Trucks probably have less of a problem with poly in suspension components due to the sheer weight, and the fact that handling isn't very good anyways, but on a vehicle (like a performance car) that you can feel every little handling charecteristic in, you don't want something that binds." Damn right you want something like a poly bushing in a performance car.... less bushing deflection means your suspension operates more accurately through its travel whcih is what you want in a perforamnce car.
     
  16. Michael

    Michael 1/2 ton status

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    In Herb Adam's suspension guru book he unequivocally states poly (suspension) bushings are BAD......due to binding.
     
  17. Sidepipes

    Sidepipes 1/2 ton status

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    I'm not trying to be rude, but who is Herb Adam's? I've never heard of the name.
     
  18. Michael

    Michael 1/2 ton status

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    You're not being rude at all. If ya don't know someone, ya just don't know 'em. /forums/images/graemlins/wink.gif I'll admit Herb doesn't hang out around "our" type of vehicles much, but he is definitely with it on suspension design. You can usually find his book at B&N, Hastings, Borders.....pretty cool info.
    Herb Adams
     
  19. Panther

    Panther 1/2 ton status

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    If I can digress for a second, this discussion on poly being bad is only for suspension bushings right? Everyone agress poly body mounts are good?

    I just priced a set of Energy mounts and was going to get them soon.

    Speaking of brand, which brand mounts does everyone have?
     
  20. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, its kind of gone off topic, but basically, yoyr body shouldn't move on the bushings, (thus no need for lubricant to prevent squeaking) so poly is a good material.

    Much stiffer than rubber, (also more resistant or impervious to oil, etc) which theoretically ties the body and frame together better than the original rubber ones. Translation? Suspension components do more work, the frame and body do less, since they are now acting together, instead of the frame moving, then the body. Should be less likely to hear the body creak and moan, and the doors should be easier to open with the suspension twisted up. Not to mention the roof shouldn't flex as much /forums/images/graemlins/smile.gif
     

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