Bushing Installation Question

"Chris F." wrote in news:4975ecbd$0$5491$ snipped-for-privacy@news.aliant.net:

It was pressed in, not glued. All the OEM bushings are pressed in and cannot rotate.

Yes, that's so the rubber doesn't eventually tear loose from being torqued all the time.

Which will eventually wash off and the bushing will start squeaking.

The trailing arm has only one bushing, and that's the great big one in the middle.

Body height is a function of the road spring, not the bushings.

The reason you tighten the suspension bolts with the suspension at its normal loaded resting attitude is so the bushings won't be torqued when the car is sitting normally.

I'd personally be worried about that big loose Prothane bushing being able to work its way out of its hole.

Disassemble the suspension. Bring the arms to a garage with a press. They'll have the old and new swapped in a half-hour.

There's nothing wrong with urethane bushings properly installed. Yes they do rotate in their shells - I think typical installation is to remove the rubber from the old shells and press the urethane into the old shells, after they've been thoroughly cleaned. I used them on my daily driver Scirocco years ago and they were still fine when I sold the car. Instead of using grease, however, I got some powdered graphite - rubbed it into the surface of the bushing until it was a uniform pencil lead color and then installed it. No squeaks after several years of daily service. The "gorilla snot" grease does eventually wash out and causes squeaks.

The only real downside of the poly is that it causes a harsher ride than rubber. IT's a tradeoff - if you want more precise handling, you have to put up with a little more NVH.

nate

Nate Nagel wrote: Instead of using grease, however, I got some powdered graphite -

Or you can just buy "Polygraphite" (a trade name of either PST or Energy Suspension, I forget which) bushings, which are polyurethane with the graphite already embedded in the rubber itself. They're the only way to go in urethane if you ask me.

Well, I plan to thoroughly cover everything with undercoat once installed, to make sure water never gets near that grease.

For me it wasn't so much a question of handling, it was price; the Prothane kit was much cheaper and more readily available than original Honda parts. The poly bushings are also supposed to last much longer. And better handling is very desirable, since this car will mostly be driven on bumpy back roads. Is it possible to compensate for the increased vibration, by using higher quality shocks/springs and/or lowering the ride height?

I used those on a '69 Valiant once (it is PST BTW;) I would still rub some extra graphite in there. I didn't do it on that car, and they creaked a little.

nate

All of that will degrade ride quality on bumpy roads, except for using a variable-rate shock absorber if you can find one. Lowering springs are generally higher rate and will result in a stiffer ride.

nate

Hard bushings transfer high-frequency vibration to the chassis more readily than rubber, which causes a general increase in NVH in the cabin. Its a path for vibration from the unsprung components directly to the chassis, and changing shocks/springs/etc won't affect it at all. The factory made a compromise on bushing stiffness to make the cabin quieter and more comfy. If they didn't HAVE to do that, they'd use solid metal or other hard coupling materials (Delrin, for example) and eliminate all compliance in the bushed joints. Urethane is just a little more to the "performance" side of the compromise than the factory rubber, which is on the "comfy" side of the compromise.

Some suspension designs are made with the rubber bushings in mind and switching to a urethane or delrin can cause bind in the suspension or even damage to the car or suspension bits because those materials do not deflect the way rubber does. These designs are probably limited to some cars with solid rear axles and such.

"Chris F." wrote in news:497743a0$0$5463$ snipped-for-privacy@news.aliant.net:

You cannot keep road splash off the bushings.

Any undercoat will crack and flake off quickly. Remember, those bushings are moving with the suspension.

Ask yourself: WHY are they much cheaper?

I doubt that. The OEM bushings already last over 15 years. Longer in places that do not experience rust.

Then stay with the stock bushings. Urethane bushings will make the ride a lot harsher.

What tells you that you need to replace the bushings, anyway?

Drive more slowly.

Actually I'd bet that virtually every car on the road has at least SOME link in its suspension that relies on the flex of a bushing to "cheat" on the geometry a little. Except for perhaps rear leaf springs on solid axles, where the spring itself is the cheat.

Well, I wouldn't necessarily say it will be a "lot" harsher. Harder bushings transmit more *high* frequency small-amplitude vibrations- stuff like grooved concrete and rough chip-seal pavement will be more apparent. But you won't feel speed bumps, potholes, washboarded asphalt, or other large-amplitude suspension movements all that much differently than with stock rubber.

Steve wrote in news:wuqdnS45tZkXNerUnZ2dnUVZ snipped-for-privacy@texas.net:

Feels that way, in any case.

I guess if you're young and like loud mufflers the added jitter won't bother you. Me, I'm too old for all that.

But you won't feel speed bumps, potholes, washboarded

True. Bushings don't seem to have much to do with sudden large inputs.

Maybe that's why the poly bushings are greased and allowed some movement - to imitate the flex of rubber? I haven't ordered the large T-arm bushings yet, I'm considering getting polyester ones which are (according to the manufacturer) 25% softer than polyurethane. I'm assuming these two (one on each trailing arm) transfer the most vibration, so if the new ones are soft enough maybe there won't be such a big gain in vibration. Either way, isn't anything bound to be an improvement over the original, worn-out bushings? Most were badly cracked and some were actually flaking apart.

"Chris F." wrote in news:4977b258$0$5464$ snipped-for-privacy@news.aliant.net:

They don't. They just allow the most MOVEMENT. That trailing arm squirms around all over the place in all directions as the suspension does its work. The big bushing is sort of the central datum point for all the arm's motion.

Any harshness would be due to all of the smaller bushings in the system (and there are a lot of them on this car).

You'd think. But so long as the rubber isn't almost separated from the steel sleeves, the bushings are still pretty much doing what they're supposed to do. Other than a busier ride, you won't feel a lot of easily perceptible change in the vehicle's behavior with new urethane bushings.

The cracking and flaking you see is usually just at the outer edges. It looks bad, but the internal bonding is still OK.

You want a real change in the car's behavior? Replace the shocks. Bet your fronts have about had it by now.

Yes, the struts and springs are all original, and well-worn after 20 years and 262,000 km of wear (all struts are showing signs of leakage). I plan to replace them also, but the question of what to replace them with is a subject for a future topic.....

"Chris F." wrote in news:497898a3$0$5463$ snipped-for-privacy@news.aliant.net:

They're leaking? Then you will see a BIG difference in handling once the shocks are replaced.

If your Honda is 20 years old, you don't have "struts", you have what Honda calls "dampers". These are shock absorber assemblies that incorporate the spring mounts. Unlike struts, these units have no suspension locating function.

Forget the bushings. Do your shocks instead.

OEM is about $180 each and will last another 20 years. Aftermarket is cheaper and might last five. The shocks are easy to replace, even when you need to swap the springs over.

Sounds like the front suspension on a '65 Falcon to me. Ford also played with putting the shock through the spring to save space while not actually using it as a suspension link. What a PITA....

Have you ever actually worked on a 1965 Falcon (or Fairlane, or Mustang from the same era)? The Spring and shock were mounted above the upper A arm. They acted on the upper A arm and against a pocket formed in the engine compartment sheet metal. Removing a shock was not particularly difficult, even though it was inside the spring. You just disconnected the shock at the bottom, unbolted it at the top and pulled it out. Nothing particularly difficult about it.

Ed

What about high-end brands like Koni or Bildstein?