cyteone

iTrader: (1)

I recently installed a set of 4.10 gears & Slp bolt in subframe connectors. After installing and driving the car around, I noticed that it is very harsh in the rear. When I hit bumps I now feel a distinct thud from the rear end when the suspension compresses.
It reminds me of my brother's 91 firebird with 140k because his suspension is beat. My car has always felt way better on bumps than his, but it started acing more like the 91 after the subframe install.
Is it harsher because the subframe connectors made the car tighter removing play from the chassis and now the shocks have to make up for the added stiffness?

I have Decarbon shocks with about 70k... was thinking of getting some Koni 4/4s. Would this make the car feel a lot smoother in the rear?

While turning I've noticed a slight squeak that seems to be coming from my rear end. A Buddy of mine suggested this might be worn bearings in the rear end and that after the 4.10 install they will wear out faster. The new gears also whine a bit on the freeway. The car feels like it accelerates and handles great other than these few things.
I was thinking of getting a Mac rear cover Girdle, do these help make the rear end quieter? Any suggestions for making the rear quieter?

Any advice would be greatly appreciated.

DirtyHO'SS

Some gears are louder than others. Were they installed properly? I doubt a cover (girdle) would make the rearend quiet.

cyteone

iTrader: (1)

A shop called Rearend Specialties did the gear install, I would think that they were installed properly but you never know. The gears are stock GM from an s-10. They were used maybe this is why they are louder? The looked like they were in great condition before installing.

Element

iTrader: (5)

Koni's will do a lot to make the rear end feel better. You may also want to check your bushings - if they're still stock, they probably look pretty nasty after ~17 years.

As far as the girdle, I've had one on my 10-bolt since the 4.10s went in and it still whines like a banshee. It's just an all-around useless axle.

soulless

iTrader: (3)

The thud you here is your shocks bottiming out, more than likely. The decarbon shocks are known to be an issue.

meine96ws6

iTrader: (4)

They aren't supposed to "thud".. my shocks have about 78k on them and I don't get anything like that.

DirtyHO'SS

They were used maybe this is why they are louder?

Might be part of the problem, you never know with used gears. Hopefully they are just loud and maybe you wont have problems

Sam Strano

iTrader: (41)

The addition of the SFC's took compliance out and added some spring rate to the chassis and now you are feeling what is really going under the car more--and yes, better shocks like Koni 4/4's (which I still have on special for $939.99/set) will make a HUGE difference over 80k miles deCarbon's in terms of ride harshness.

As for the whine... This isn't unheard of when adding boxed or tubular LCA's as they transmit more noise up to the body. It's rare to hear that with no LCA change you see such a difference. But the LCA's do bolt up at the back of the SFC's.... so it could be more of the same you just gave harmonics a path to travel and get closer to you.

cyteone

iTrader: (1)

Thanks for the heads up on the shocks, but I have a buddy who bought a set of konis for a 99 Camaro and never installed them and he is willing to sell them to me for $750.
I do plan on getting a set of your lowering springs and sway bars when I get some extra funds.

I checked out my bushings today and most look okay (not cracked) except for the shock & panhard bar bushings. I'm gonna replace them when I do the rear shocks.

If I run the front konis on the lower perch, and do the heater hose mod in the rear, I 've heard this lowers the car 1/2 -3/4 in. Will this mess up the suspension geometry? Will I need an adjustable panhard bar and LCA relocation brackets?

SS4Luck

iTrader: (10)

anytime you change ride height you will more than likely need something to re center the rear.


the gears could be louder because they are used. Who knows if they were installed and the wear pattern is the same, if its off just a hair it will make them louder cuz your pushing on parts of the gear that have never been used before

cyteone

iTrader: (1)

Got my Konis today and started to take the old shocks out. I got the fronts out and am going to take them to a shop tomorrow to have the coils switched to the new shocks. Will finish installing tommorrow. I can't wait to drive the car. I will post results once finished.

libertyforall1776

iTrader: (2)

The "thud" you are hearing I will bet is the exhaust hitting the body somewhere -- check that and see if your exhaust is tight and bushings are good... Also, are your bumpstops in good shape? Your shocks may be shot too... Also, I would weld in the SFRs for more stiffening.

z28bryan

iTrader: (7)

My exhaust usually hits my underbody under accelleration. Not really going over bumps. It hits due to slight engine rotation counteracting the rotation of the driveshaft.

Gear whine I thought was usually caused when not installed right. Maybe the SFC's cause you to hear it more transmitting the sound better.. but they are still whining

cyteone

iTrader: (1)

Got the koni shocks installed on the car. I used the lower perch and did the heater hose mod in the rear. The car looks much better but now I scrape pretty bad when pulling out of my driveway.

I measured the car from the ground to the fender gap; without shocks and hose mod it was 26 1/2 inches in front and 27 1/4 inches in the rear. Now it is 25 1/2 in the front and 26 1/4 in the rear, so it lowered the car about an inch.

The shocks did not fix the sound coming from the rear, so I jacked it back up to look at it again. I found the rear control arm on the passanger side will move side to side if I push on it. The bolt and nut that hold it together are very tight, I could not get it any tighter. Why would the control move side to side if the bolts are tight? Is it because the bushing is kinda beat? It looks like there is a little play between the control arm and the mount on the car, like the control arm isn't wide enough to sit tight.

libertyforall1776

iTrader: (2)

^ Sounds like new bushings are in order. Might want to look into replacement LCAs as an alternative...

Sam Strano

iTrader: (41)

Sounds to me like the press fit of the bushing in the control arm isn't any good and allowing the arm to move around (the bushing will stay in place when bolted in). That means new LCA's. I had this happen on front arms that have had a lot of bushing changes and eventually the bushing just won't stay put in the arm....

cyteone

iTrader: (1)

So I guess I will be getting a pair of rear lower control arms with new bushings. I can't justify spending $28 for each sides bushings when sets are about $110.

What is the point of the adjustable control arms? Are they needed for street use? If they make the car handle a little better then it might be worth the extra $$$.

What about LCA relocation brackets, should I do these at the same time? The description states; "Relocation brackets have two settings to allow the lower control arm to be lowered either 2" or 3". Do I need these if I'm lowered an inch?

If I get adjustable control arms would I still need brackets or do they do the same thing?

Sam Strano

iTrader: (41)

Adjustable arms are to square the axle/body up when viewed from above. They don't make the handling any better unless the axle is kind of cockeyed in the car. That generally only happens on cars that have been wrecked, or maybe have had LCA brackets welded on incorrectly (or on some aftermarket axles that don't have the best QC ever).

Brackets do a different job than adjustable LCA's. And I don't think they are required, in fact from a handling side the car is more stable at your mild drop without them. But they can add rear end grip in a straight line... though you'd want to keep the arms as level as possible if you opted for them. They are best used on cars with lowering springs, but based off your numbers, your car is pretty low--so you could use them if you wanted without trouble.

cyteone

iTrader: (1)

Thank you Sam, that is exactly what I wanted to know.

I will be going with UMI non-adjustable arms and no LCA brackets. I know I need an adj. panhard bar too but that will have to wait as I just spent all my money on shocks.

Sam Strano

iTrader: (41)

I've got the full UMI line..... take your pick.