Johnnybgoode

I completed all of the suspension mods on my SS. Car rides fairly stiff but handles great and I'm quite happy with it. Had to swap out the SLP Level 1 springs for Eibach Prokit but left the SPL's on the rear and I think this provides quite a good set up. Nice stance, front (26.5") rear (26.75") and a bit stiffer/taller spring in the rear. Just expensive and a lot of dicking around to get it the way I like it.

Had the car aligned as follows:

Caster 4.5 / 4.7
Camber -.8 / -.9
Toe 0 / 0

My question is if I hit a bump in a fast sweeper the rear of the car feels like it wants to step out a bit. Just my seat of the pants feel. I'm wondering if this is just me feeling the car being more neutral and responsive or if it is something else I have done.

The car has the stock 32MM front bar on it but I upgraded to the 21MM rear bar, new poly end links and poly bushings all the way around as well. I'm not sure if this is what I am feeling. I also installed SLP rear LCA's with poly bushings. I lubed these and torqued to factory spec's. I also installed a Spohn adjustable TA and have adjusted the rear to be perfectly centered with the suspension loaded and also torqued all rear bolts with the suspension loaded and nothing feels loose when I try and push the car from side to side so I'm pretty sure I have everything tight.

The only thing I can think may be a problem is that it was very difficult to properly torque the LCA's to the body on my jack stands. I'm wondering if these were not quite tight (manual says 80 ft/lbs for the bolts and 60 ft/lbs for the nuts, which I'm at) would it make the rear-end feel loose? Should I be tightening these things up more? say to 100+ ft/lbs?

There are no bangs or rattles everything seems tight, just this funny seat of the pants feeling that the rear wants to step out when I hit a bump in a long sweeper. Probably just my imagination, but don't want to end up in the ditch some night either.

Any ideas are welcome. Cheers Scott

trackbird

iTrader: (4)

Shocks.

The bump is upsetting the car because the shocks are not damping the wheel motion and keeping the wheels on the ground. A wheel that is airborne is not making grip. While the tires are in the air, the rear of the car will start to go in a straight line (the tires are no longer making it turn and it will continue in a straight line which is why it "steps out").

I'd consider finding a shock to match that spring. As each spring and vehicle is different, I'd hate to make a recomendation as to what will work. I am using Koni DA's, so I just adjust until that problem "goes away". You may check with Sam at www.stranoparts.com for a revalved shock for your application.

Also, I'd consider removing those poly bushings on the rear. When the body leans in a corner, those bind up. Once they bind up, the axle becomes harder to move. This has the same effect as adding more spring rate. It is hard for your shocks to do their job when the effective rear spring rate keeps changing (each corner has a different radius and the body roll will vary with radius and speed). So, you ahve a few things working against you. I'd start there.

TTopJohn

He's got bilstiens on there, which should be enough to damp the SLP springs (SLP Eibachs I assume?)on the rear.

I think it's just that the rear is too stiff, due to the 21mm bar in combination with the poly LCA bushings. So I agree that ditching the poly LCA bushing is the way to go.

Johnnybgoode

Thx for the advice Guys. Yes I forgot to mention that I have a new set of SLP Bilsteins installed which hopefully should be matched for the rear springs, and yes they are SLP Eibacks.

I will look in to new LCA's. I bought them before reading the advice on this site, they are actually nice pieces, very beefy but I can see that they may bind.

If I upgraded to a 35MM front bar do you think this would provide a better balance?

Also the back end is not coming off the ground it just feels loose sometimes, like if I'm driving down a straight highway at 60-80 MPH and wiggle the wheel back and forth the back just feel loose (feels like it is swaying back and forth, not firmly connected to the car). If the LCA's were not tight enough is there a chance they could be changing the angel of attack/tracking of the rear tires and this is what I am feeling? I know the rear end is not moving back and forth since the PB is keeping it centered and it's completely tight (and beefy) so I'm wondering if the front of the rear suspension could somehow be moving? But I guess I'd probably hear some clunking or banging which I'm not.

Anyway Thx in advance for any further thoughts you might have.

trackbird

iTrader: (4)

The swaying is possibly a result of too little rebound damping. More rebound damping will "speed up" the response of the car and less damping will allow the car to transition more slowly (and possibly sway). However, you will have some "motion" in the vehicle, if you have too much rebound, the car can be very nervous and will "skate" and slide over bumps.

I read your original post to say that in a mid corner bump it was "hopping" and the rear was stepping out. That is typically a damping problem. I understand that those shocks are a "matched set", however, they were designed for street use for the general public. Meaning, this is why they are a little on the soft side. They had to try to make everyone happy and couldn't run them as stiff as a performance shock for a true racing application would be. When I say "stiff", I actually mean "aggressively valved". Stiff, in and of its self, is not always the right answer.

I've played with settings on my Koni DA's and can tune out or tune in the rear "stepping out" over mid corner bumps. So, I can tell you it can be changed and possibly fixed with correct shock settings. However, your poly lca's are not making finding that setting easy.

lsx24

iTrader: (45)

I would have to agree with Trackbird, but also have you checked the free play on your PH? That may be indicitive of an axle that steps out.

69TA

iTrader: (263)

To: Mitch and Trackbird,
Are you suggesting that this guy should go with a set of spherical rod ended LCA's? I ask, as I was thinking about switching out my Poly LCA's (I think mine are binding as well).

I currently have a SPOHN spherical rod ended PHR and it transistions real nice but it's quite noisy.

In your oppinion will changing the LCA's make a big difference? There's no grease fittings so will they hold up under street use? And will they be even louder than my PHR.

Thanks,
Kevin

mitchntx

iTrader: (14)

Kevin, a good rod end will last a long time. I've had LG Motorsports rod ends on my car for over 2 years and they are still quiet. I clean them once a year with brake cleaner and use a spray on graphite for lubrication.

A good rod end should give you no clunking noise. Some report an increase in road noise, however, I can't hear it over the exhaust and radio.

A good rod end costs the vendors $40-50 each ... so, getting a rod ended set of LCAs for $200 is impossible. That's dealer cost for just the ends ....

When I went to a rod end LCA, the car's characteristics changed dramatically. When I had poly ends, the car would turn and then at some point, would snap ... sometimes oversteer, sometimes understeer. This was the instant the bushing bound in the mount.

With rod ends, the car is now predictable and controllable. It reacts the same way each time.

Nothing like the queezy feeling one gets, sliding the car through T1/2 at Texas World Speedway at 120 mph and not knowing what to expect the *** end of the car to do.

trackbird

iTrader: (4)

See my post (post #16) here:

https://ls1tech.com/forums/suspension-brakes/202648-going-run-bmr.html

I think Spohn has upgraded his parts to the better rod ends. I don't know when this took place and I don't know if you have an old part with the "lesser" ends on it. Usually, PHB's are not noisy, even rod ended ones with cheap ends on them. The shock loads are not usually high enough to make it rattle, in most cases anyway.

Rod ends trade comfort for handling. Mitch pretty much covered it. It is a decision that you have to make for yourself. Some don't mind, some hate them. Some guys say they are quiet (mine usually are), some guys say they are obnoxious (cheap ends, sensitive driver?). So, only you can decide.

Johnnybgoode

Mitch what you describe as the car snaping is exactly what I am experiencing. I can even make it happen at relatively low speed going around a tight turn in my sub division. Crank the car really hard and the backend will all of a sudden snap and I sometime have to catch the car.

So I am thinking I should replace these poly LCA's. What kind would you recommend? Double ended or poly spherical?

Thx a bunch Scott

trackbird

iTrader: (4)

Either.

Poly/spherical will help to eliminate the worst of the binding that poly is known for and transmit less noise to the vehicle in the process. So, it is a much better compromise than poly/poly.

Heim/Heim will make sure the rear stays essentially "bind free" throughout its range of motion. The negatives are that you have 4 rod ends to replace if/when they wear out (they are a wear item and do eventually wear out) which will cost more money. The other thing is that they don't damp any of the vibrations that a poly/heim LCA might absorb. Is it a big deal? Not to me. Good rod ends are not that noisy, at least not until they wear out.

My thoughts.

skytower31

iTrader: (4)

A bit of a hijack, but I installed some Spohn rod/rod LCAs a few weeks ago and they are VERY noise. Over any bump in the road, they make a horrible clunk noise that sounds like the rear end is going to fall off the car! I have checked them many times for tightness and they are tight as can be. They sound like they are banging around loose back there. Could I have some bad rod ends on there? These were brand new from Spohn a few weeks ago so unless I got an old set, these should be the QA1 ENDURA 2000 Series (XMR12/XML12). Any recommendations would be great.

69TA

iTrader: (263)

Hey Skytower31,
I know what you mean. I have a Spohn rod ended PHB and she too makes a lot of banging noise. After awhile I just got used to the noise. It's the nature of rod ended parts.

If you are interested in swapping your LCA's out, I have a pair of new tubular LCA's with poly ends w/grease fittings.

Regards,
Kevin

skytower31

iTrader: (4)

Seems like according to these guys they shouldn't make that noise. I dunno...if anything, maybe I'll swap to a poly/rod setup.

Trojan T/A

iTrader: (1)

skytower, at the next meetup, give me a ride and I will tell you if the noise is normal. My rod ends dont make much noise except when driving over something like a lane marker. This is a louder than stock sound and obvious that there is no rubber cushion anymore. And after we check yours out, you can try to troubleshoot my problem which no one can figure out.

skytower31

iTrader: (4)

Cruising down the road at highway speeds they are very quiet. Lane markers or large cracks in the road will set them off. Or on surface streets, even minor surface variants will cause the loud noise.

We shall have to compare next time we are all together.

trackbird

iTrader: (4)

Some do sound that way, but QA1's XM series shouldn't.

skytower31

iTrader: (4)

So you think I could have some non QA1's in there or damaged QA1's?

trackbird

iTrader: (4)

QA1 makes several series of rod ends. Some are ok, some are bad, and the XM series are very good. If they are XM series, they will have 2 "black stripes" on opposite sides of the bearing (the ball in the rod end) that are where the ball is assembled into the housing and then filled with a polymer. Also, the housing will be a thick housing with square edges (not the tapered look you get when one is crimped in place), it will be a much heavier housing than many others.

http://www.qa1.net/rodends/endura/endura_xmrxml.html

You can see the shape of the body and the drawing shows the two black "stripes" that I mentioned.

Hope that helps!

skytower31

iTrader: (4)

That definately helps. That is what mine look like. I have also realized that it is mainly the passenger side that is making all the noise so I think I have some faulty ends. I'll try contacting Sphon. Thanks for all your help everyone