MisterMidlifeCrisis

I've got a 2011 base coupe with F55, upgraded to Z51 sways. I also have played with the ride height, lowering it moderately up front,and barely any in the back, and also did a crude corner weighting before an aggressive Pfadt-specified street alignment. Wanting a hair more roll stiffness, I ordered these from Pfadt:



Just sitting there, the material is way stiffer and a lot less compressible than the OEM bushings. The front bushings also have been pretty significantly ovalized on their outer sides because the mount point is a bit too outboard and so the bar's bend starts before it exits the bushing.

The poly bushings also seem a little larger than OEM (or maybe the OEM ones are just compressed into a smaller size). The Pfadt bushings take quite a bit of torque on the bolts to snug up the holding plates.

It took about an hour from beginning to end to install the bushings. The difference is immediate and pretty significant. The roll stiffness is noticeably higher, and it also seems the spring rate is a bit higher (probably because with the new bushings, the bars don't rotate well in the bushings yet). There isn't any more NVH. The cornering limits are higher, and transitional handling is much sharper.

Now the bad. The car now skips a bit on chatter bumps when loaded up in the corners, almost as if it's too stiff. And when it skips and catches under throttle, it can grip and hook almost violently. The breakaway is more sudden and a little harder to catch. The handling balance is now more sensitive to throttle manipulation when cornering, moreso than I'd prefer.

I think for canyon carving, where you keep 10-20% in reserve, it's now better, but for driving on a track, it's more demanding that the driver be skillful and I'm positive I will have my share of ham-fistedness.

Has this been the same experience for others who have swapped bushings? Did you then do anything to the suspension to try and change the handling?

niteriderc5

excellent insight...I felt the same way about Pfadts sway bar poly bushings. I ended up going back to OEM for just the rear. It's much cushier and stays more planted over rough cornering

el es tu

The less rubber, the less slop. The car should be easier to push harder, but harder to eek out the last amount of handling.

If youre having trouble with mid turn throttle control, you can do a few things to cause understeer, and/or add more grip to the rear.

running the softer bushing in the rear and stiffer up front is a free option that Id look into first. also you can drop your rear tire pressures a bit (Id start with 2 psi)

condition of your tires can also have huge impact on this - what tires are you running, how old are they, and how much tread do they have - also are they cracking?

if the car still doesnt feel the way you want it to, and you want to keep it relatively stock, you can just upgrade the front spring to z06 (balances out the relatively stiff rear spring that your car comes with), and/or front swaybar to the zr1.

TMyers

It is doing what is suppose to do. A couple of things to do. First did you lube the crap out of bushings. I put it on heavy and let it squeeze out. This insures you have no dry spots. FYI I drive my car every day and you will need to re lube about once a year. It will also loosen up with time. When you re-lube next time you will find that the paint has been worn away. IMO when that happens it is great.

MisterMidlifeCrisis

Yes, more planted at every speed, and ultimate cornering limits are higher, with the one exception being chatter bumps at mid-corner upset the balance more than before because the tire becomes airborne more easily.

The throttle sensitivity in handling balance is greater than before, which would be fine except that I don't often hit my corner entry speeds exactly. So, if I have to let off the throttle significantly, I get quite a bit more oversteer, whereas if I go in too slow and get on the throttle a bit early, it seems to understeer more too. It's not a problem if I get the corner entry speeds right, but on a track, I maybe only get it right about two out of three if I'm going well. It is easier to place the car, but if I have to make a more major correction in placement or attitude, the throttle alters the handling balance too much for my liking.

I did drop tire pressures a couple of PSI to try it, but it still skips on chatter bumps that didn't use to upset it.

MisterMidlifeCrisis

The bushings came with two tubes of really thick, sticky lube, and I used it all. Where did you get replacement lube? This is a daily driver for me too.

So, after the paint wears off, did it change the roll stiffness?

And like we were talking a while back, the base front spring is a little too soft and the extra roll stiffness lets the car corner harder, which magnifies the spring rate imbalance. I've really got to get a Z51 front spring installed soon.

TMyers

I don't know who makes the lube, I have just called Pfadt and they sent me some.

After the paint wears off the sways work better by reducing binding. This may just be in my head but it seems to me the suspension works better as some miles got put on it.

Yep, front springs are a problem, to much dive entering a corner. I have got used to it and actually like it now. Get most if not all the braking done before the corner. If I enter to hot the car will understeer. To much throttle on exit and it will oversteer. Just right and I can drift it a bit. Just takes practice. Actually I will be interesting in your results.

MisterMidlifeCrisis

Wow, you won all those trophies on a base front spring?? Okay, I won't complain any more!

Well, maybe just a little bit. Just like the poly bushings seemed to have increased the sensitivity of the handling balance to throttle and braking in mid-corner, it also seems to have increased the sensitivity of the handling balance to turn-in. There seems to be less tolerance of going in a bit too hot and having to be hard on the brakes than in any of the models I drove at Spring Mountain, and even there, the GS seemed the most forgiving, the Z06 the sharpest, and the ZR1 the least forgiving, but even then more so than my car with the spring imbalance.

TMyers

Yep, I have learned to brake early, set the car and then use the throttle to keep the car set. If I pick the throttle up to early, prior to mid corner the car will push. To hard on the throttle after mid corner to exit and it can snap. As I said after 2 years running like this I have gotten use to it and actually will induce oversteer/understeer if I am not online with the corner. This is in autocross only though.

This year I am thinking of putting Johnny O'Connell Sway Bars on. With going up to the r-compounds last year even the Z51 sways lean pretty good.

Again I look forward to seeing your change with the springs and if the F55 shocks will handle them. I really hate the front springs on the big track. Down in Portland the front straight is about 150mph slowing down to 35mph for the chicane. Hard on the brakes and it feels like the rear end is airborne.

Pfadt Racing

The lube that we send out with all of our poly kits is Energy Suspension: Formula #5. We've found it really does work the best, and is really resistant to breakdown via moisture or road contaminants.

You can get it through most of the online parts stores in either little tubs or big tubes for zerk fittings, the big tubes are pretty expensive and I imagine given the viscosity of the lubricant relatively hard to pump out of a gun.

MisterMidlifeCrisis

I'm not near your driving skill level yet, and having some lean helps provide me information as to how hard I'm cornering. My prior experience with a really stiff sway bar was years ago and not a good one. It seemed that by keeping the car really flat, when the tires let go, they let go suddenly and were hard to recover. The same car with the same tires but with a bit more roll probably had slightly less ultimate cornering grip, but the limit was easier to find and much easier to recover once it was exceeded. Is that your experience too?

I definitely have the suspicion that the dampening of the F55's is not quite as good now at 11k miles as when they were new. I get a little bit of pogo'ing in tour mode, in certain places where I never had it before, but that also goes away in sport mode. For a smooth, high friction track, I can see where they might not be adequate.

MisterMidlifeCrisis

Yeah, the stuff is pretty gooey, and was hard as heck to get off my hands too. I don't see how it would easily wash off, but I'll pick some up just in case.

Are there any symptoms that I need to relube other than noise?

Pfadt Racing

Not really. If you go a pretty long length of time without servicing them that's perfectly normal. You might want to add it to a yearly checkup list and that should be great.

MisterMidlifeCrisis

Thanks. Will do. They seem to be getting more compliant as I get a few hundred miles on them, and maybe the bit warmer weather helps too as we're finally making it into the low 60's now after a really brutally cool and wet winter.