Started Suspension Work--Need Help to get it Right

[Mr D]

03 GTP. 125K mi. First time working on suspension.

Bought the car about 9mo ago, terrible, soft, squishy suspension, and rear was sagging about 1". Finally getting around to doing the struts. I shopped around and decided to spend $ on fronts for now, and do minimal on rear. I went w/ KYB Excel-G, f #339015 & r #339148. I chose these because of their fitment for '04 Monte Carlo spec handl & '07 Monte Carlo w/ 17"/18" wheels. I plan on getting 18" wheels this year and did not want orig ride, wanted improved handling.

Rears--I just got new strut and Monroe top plate, and reused everything else. New KYB seems to be exact same size on what was on their (like OE struts).
1st, I thought ride height was a factor of the spring, but the new struts (w/ orig springs) raised the back about 1".
2nd, the handling is drastically improved.
But, 3rd, they are loud--rattling and squeeks.
What gives? What can I do to quiet the ride?

Fronts--I did the day after rears--HT Motorsports coil over kit w/ 350lb springs.
1st, unbelievable changing strut system could have such a huge impact on the car, all-around improved handling & practically eliminates body roll even @ higher speeds. All cars should have coil overs.
2nd, 350lb is WAY TOO heavy for my use, streets, car-rattles and bangs like crazy-so I am putting 275lb springs on this weekend.
3rd, WAY TOO loud for my urban dd, so does anyone w/ co have suggestions for isolators or anything to quiet them down?
4th, bad vibration @ low speed & under hard throttle. Intitally I had dropped it about 1.5" and shaking was almost frightening, so raised it 1/2" and still shakes but managable now. So I ordered ZZP engine & tranny spacers. I was thinking of using them for a template and making some from 1/4"-3/8" stock, so I don't have issue of mount bolts not being long enough.
Is that going to correct issue?
5th, taking to shop for alignment when I get new springs on.
What bolt holes should be expanded for camber adjustment, top or bottom?
And should they be expanded inward towards tranny, or outward towards wheel?

On a last note, for those looking to upgrade, my experience with Richard @ HT Motorsport has been good, I would recommend to friends and family to do biz w/ him. Seems to be small shop, but he seems to care about his work and seems to know what he's doing.

Thanks!

 

[Bio248]

something is wrong with the rears if they are making noise. make sure everything is tight, namely the upper nut holding the strut shaft. it's fairly natural that it would raise the rear end with fresh suspension components.

for the fronts, weird that 350# springs would be too much for you. that's a fairly typical spring rate for a set of coilovers, really. find some spring isolators for the springs and make sure all of the rubber mounts are in the correct position and orientation. the vibration is a known issue with lowering. the spacers should help with this, but while you are down there replace your motor and trans mount which may be the culprits of nearly all of the vibration anyway.

for the alignment adjustments, slot the upper holes.

overall, nice review. glad people are going more for the coilover route instead of springs.

 

[Mr D]

Thanks Bio.

A co-worker told me at lunch to check the strut nut, said he had similar problem until he tightened it down "all the way". It ought to be a real joy to get to the nuts with the struts on, lol.

Ya, concrete jungle. People don't get it until they live here and drive on the mean local streets. Construction trenchig, speed bumps, speed humps, sink holes, and the potholes here will jump out in front you from no where. I asked Richard about spring rates, he said 95% of his orders are for 350#, so I went with that, and they are great on the open road, but I rarely get to drive on the open road, even the "freeway" is 30 mph bumber-to-bumber most of the time I use it.

Hope to do spacers this weekend, and will inspect mounts then. I've been suspicious of them. Just more $.

Should I slot the holes inward, outward, or both?

 

[Bio248]

dont worry, i know where you're coming from. milwaukee streets are trash. i have been through chicagoland enough times to know i hate driving there.

the slots should be slotted both directions. do some basic geometry and figure out what you need to do, but you really dont have to slot them much. an inch of adjustment is usually like 4-5* of adjustment for camber.

 

[Mr D]

Great.

Thanks again Bio.

 

[Mr D]

HOLY SH!T--I'm sooo F'N HAPPY! Bio, you're aewsome.

Took 10min, 90'/# 12V hammer drill on front top nuts, tightened down about 1/4" ea, allen & open wrench on rears, drvr made about 1 rotation & pssngr about 1/2 rotation & ALL GOOD! Amazing, my 1st time doing struts...

Rides like its supposed to.

Kepping the 350#s. & can't wait for traffic to clear so I can do a few on/off ramps. after 9mo of plugs, fluids, filters, hubs, brakes, wipers, ignition, lights, gauges (EBCM still needs rebuild-lol)...my car is finally safe to drive my way.

& thanks theotherNick for the how-to w/ pics.

Better, Stronger, Faster.

 

[Bio248]

glad to hear everything went together well for you.

 

[Mr D]

I got the m&t mnt spacers in this weekend. Ordered from ZZP, 1/2" alum(?) stock. The holes on the tranny mount were way too close together & had to be drilled out. But works as advertised, slight vibration at idle, not an issue to me, and corrected accelloration vibration.

DId not replace mounts themselves, 1/2 because I really did not know what I was getting into, and 1/2 because my local parts stores did nnot have them in stock. Tranny mount looks pretty good considering, motor mount looked more worn, no visible signs of leaks. I will likely replace them in the next few weeks w/ solid rubber mounts, but car handles pretty good for now.

Thanks again!