Panicked, and ordered the Banski Motorsports trailing arms on clearance

[55 Rescue Dog]

Although the stock dog bones I have are fine, but obsolete, I was worried the Banski adjustable C4 trailing arms might end up not being available, and go out of production too, so I ordered a set at 20% clearance price. Near as I can tell they only have 4 sets left, since I just bought one. Got the $32 boots too. There is no fuckin way I would use poly on the trailing arms. With up to 3 degrees of rotation under load they will bind, and be unpredictable, and change over time as they wear in. Maybe when Porsche, and BMW use poly I will change my mind.
http://www.ebay.com/itm/C4-Corvette-...-/151834813454

[chevynut]

I suppose when you have the crappy looking 1996 fiberglass dogbones these will look better but IMO the stock aluminum non-adjustable dogbones are "best" and it would be a waste of money to change them. You might think the adjustability is nice, but it's just one more thing to align and then to go out of adjustment and wear. OH, and GM didn't use adjustable dogbones, so they can't be good . And once those heims wear (and they will) they're going to be clattering down the road. Ask people who use heims on suspension parts about the wear and noise.

http://www.clubcobra.com/forums/shop...int-noise.html

I don't know where you get 5 degrees of rotation on the dogbones. I proved to you that over a full 3" of upward travel there's about 1.6 degrees of camber gain. That's split between the two bushings so they rotate around 0.8 degrees each....AT FULL UP or down TRAVEL. 0.8 degrees is virtually nothing. Is your car really going to be bouncing up and down 6"? If it does, you should panic about that.

Tens of thousands of C4 Corvettes probably have poly bushed dogbones. They work just fine.

[chevynut]

Many sourced discuss poly versus OEM rubber bushings. I know you think rubber is the "best" but most people don't. That's why just about everyone with a performance car replaces the rubber bushings with poly.

https://www.eeuroparts.com/blog/2120...poly-bushings/

"There’s no rule, but OEM bushings generally range between 50A and 70A durometers, which is not actually too far off from the street poly bushings. The difference is that polyurethane bushings don’t weather and degrade like rubber because the chemical makeup is a synthetic polymer. Rubber is made from the sap of rubber trees, and is much more susceptible to the effects of heat, chemical contact, and age. Another main difference is that rubber twists and deforms, and polyurethane doesn’t. If you are twisting a poly bushing, expect it to tear. That’s why it’s important to always keep them lubricated."

There are pros and cons to everything. You have to decide what you're going to put up with.

[55 Rescue Dog]

Don't know how much it will help, but the heims on these are Teflon lined. Yes, I know they can be noisy like the race shocks on my Camaro are, but everything on that car makes noise like a mechanical symphony. Are the heim joints on coil overs, camber, and toe rods, etc. quiet, or just noisy when used on dog bones? Always wondered what the best way to lube poly bushings would be without taking the suspension apart every few thousand miles?

[NickP]

Don't know how much it will help, but the heims on these are Teflon lined. Yes, I know they can be noisy like the race shocks on my Camaro are, but everything on that car makes noise like a mechanical symphony. Are the heim joints on coil overs, camber, and toe rods, etc. quiet, or just noisy when used on dog bones? Always wondered what the best way to lube poly bushings would be without taking the suspension apart every few thousand miles?

Regardless of the fact that I'm not on your Christmas Card List, when you receive your new goodies, I would be interested to know if there is a manufacturer listed for the rubber boots. Consideration might be given to acquiring extras due to vulnerability in the open along with normal driving.

[chevynut]

Besides the front a-arms, the dogbones are probably the WORST place to use heims on a suspension IMO. They'll transmit vibrations from every pebble and crack on the road to the frame and to the car. You can read lots of reports on this BIG tradeoff on the internet. Also, the dogbones are always under fairly heavy loading whether accelerating or braking, and that's going to cause wear. Teflon isn't very tough stuff from my experience, and it "cold flows". There's not much surface area inside those heims to absorb the thrust and I doubt there's measurable cushioning from the teflon.

For a track car they might work great as far as predictable handling, but if you were building a track car you would be concerned about the CG and power. I think you're going to hate the heims on the street....most guys do because of the vibration and noise.

Those heim "condoms" are interesting though . Speedway and others sell seals that fit on each side of the heim that I think look better and that's what I plan to use.




I used P-S-T Polygraphite bushings on my suspension rebuild and greased everything well. Most reports I've seen say they don't squeak as bad as straight poly. I guess I'll see how they work.

"One of the primary problem areas in classic muscle car suspensions is the use of rubber bushings. They were cheap to manufacture for mass production and provided isolation from road noise and vibration, but rubber has a significant trade-off – its relatively soft durometer (hardness) allows for significant deflection of the chassis components under load. The rubber bushings twist and deform as the suspension components rotate, causing premature wear and unpredictable handling. Rubber eventually dry rots when exposed to the elements and degrades in the presence of grease and oil. PST perfected polyurethane with the introduction of POLYGRAPHITE® - a special formula incorporating a low-friction graphite lubricant into the actual bushing material. With POLYGRAPHITE®, you get the near-zero deflection performance of polyurethane with a self-lubricating bushing. As an added benefit, POLYGRAPHITE® is impervious to grease, oil, weather, and other natural elements and will never dry rot. PST has the most complete line of POLYGRAPHITE® bushings available for your musclecar. Replace components as needed, or save time, money, and reap the ultimate performance benefits by installing one of our Complete POLYGRAPHITE® Kits on your vehicle today!"

[Rick_L]

Depending on the exact materials used for a polyurethane bushing (or any polyurethane part), they can be susceptible to weather and just plain aging. Some polyurethane compounds will deteriorate with exposure to water. Polyether based polyurethanes are less sensitive than polyester based polyurethanes in this regard. There are also polyurethanes that are thermoplastic and others that are thermoset, with differing resistance to exposure.

That said, I am no chemist, and I don't know what compounds that are typically used by PST, Energy Suspension, and other automotive suppliers do with aging and exposure.

I do know this - I have seen things like shoe soles and dead blow hammers simply crumble with age. Also I have seen some problems with industrial applications of polyurethane. Ironically in the industry where I worked, we made many products from polyurethane, using it for water resistance and "waterproofing" as well as its toughness and elasticity. Ironically, water will win out vs. these products. It's a matter of time, product cost, and negative factors of competing materials.

I do agree about the isolation behavior of an elastomer vs. a rod end bearing.

[55 Rescue Dog]

I can understand why a rod end on a shock without a spring can be noisy, or a dog bone when coasting without a load on it, but when loaded they should be fairly quiet. Maybe coil overs can be quiet since it has pre-load on it, but things like sway bars can rattle for sure, or anything constantly changing directions with little load.
And, as far as the Banski trailing arms being adjustable, I can't think of anything they could be adjusted for other than a slight wheelbase correction so both sides are exactly the same to square up the front, and rear in case there was any dog tracking. I'm also assuming that to set rear toe, unlike the front, it has to be done off of the centerline of the chassis since the toe rods are not linked together?

[chevynut]

I can understand why a rod end on a shock without a spring can be noisy, or a dog bone when coasting without a load on it, but when loaded they should be fairly quiet. Maybe coil overs can be quiet since it has pre-load on it, but things like sway bars can rattle for sure, or anything constantly changing directions with little load.

Shocks are pretty much always going to be loaded, imo, unless the wheel comes off the ground. A dogbone's load alternates when accelerating or braking. Both are under forward thrust (compression) when accelerating, and the top one is under forward thrust when braking while the lower one is in tension. I assume both would be unloaded or in slight tension when coasting or downshifting. As the heims wear, I would expect the lower one to start making noise first. But even when not worn out, they will transmit a lot more vibes.

I'm also assuming that to set rear toe, unlike the front, it has to be done off of the centerline of the chassis since the toe rods are not linked together?

The front is exactly the same. To do the front toe alignment correctly the steering should be centered and each steering rod adjusted separately.

[55 Rescue Dog]

Shocks are pretty much always going to be loaded, imo, unless the wheel comes off the ground. A dogbone's load alternates when accelerating or braking. Both are under forward thrust (compression) when accelerating, and the top one is under forward thrust when braking while the lower one is in tension. I assume both would be unloaded or in slight tension when coasting or downshifting. As the heims wear, I would expect the lower one to start making noise first. But even when not worn out, they will transmit a lot more vibes.



The front is exactly the same. To do the front toe alignment correctly the steering should be centered and each steering rod adjusted separately.

Not that it is a big deal, but the shock mounts unload in rebound on every bump trying to resist the spring. Under acceleration the top dog bone is in tension, and lower one compressed, and opposite on braking. The front toe could be set to zero with the steering wheel half turn off center, which you wouldn't want to do of course, but it would go straight down the road. But the rear could be set to zero with both wheels pointing left or right, which would make it dog track. No problem setting it up on a alignment rack, just a little more challenging to do at home without stringing the centerline of the chassis is all.