Too stiff up front? Koni front vs. Bilstein rear

[sugarwood]

At my DE tech out, the tech said my car seemed very stiff up front.
When he pushed down on the rear bumper, he could get the rear to bounce once.
But when pressing the front bumper, he could barely get it to move and bounce.
Is this normal?

I noticed my front shocks are green, and my rear shocks are yellow.
Could one explanation be the PO have installed extra stiff shocks in the front?

I suppose this could also be worn bushings, which would make the ride a lot stiffer and harsher, as new rubber is softer and more forgiving.

[prschmn]

If your front is Green-those are Bilsteins-verify by looking for a roll pin at the bottom-above the ball joint. Yellow rears are Koni adjustables-you may want to check the setting.
And the fronts could be a number of valving options-you need numbers off the insert...

[Reiver]

With the weight difference/imbalance I put Boge stock shocks up front and Bilsteins in the rear with heavier sways on both ends....nice balance.
Both ends suspensions rebuilt with stock rubber except the rear spring plates.
A nice street set up that is still aggressive but not crazy uncomfortable.

[Drisump]

Stiff up front would likely result in understeer. My 3.2 has Bilstien greens all the way around. Seems to be a nice, crisp street set up. Cheers

[Monza_dh]

Green Bilstein HD inserts up front with Sport yellows in the rear is a popular combination. I have both and agree that there seems to be more travel in the rear but there's not much weight up fronte compared to the rear obviously.

If it barely moves maybe there is more of an issue with arm bushings or indexing?

[sugarwood]

The suspension rubber might well be original fro 1986.
I might try to tackle that project this year.

How would bad arm bushings stiffen the suspension?
(I know nothing about how suspensions work)

[Trackrash]

Originally Posted by sugarwood

At my DE tech out, the tech said my car seemed very stiff up front.
When he pushed down on the rear bumper, he could get the rear to bounce once.
But when pressing the front bumper, he could barely get it to move and bounce.
Is this normal?

Sounds normal to me. At least that is the way my 911 has always been. To get my car to bounce in the front, I have to jump up and down in the trunk. My car's handling is neutral.

Was this "tech" experienced with 911s? I have never seen a "tech" bounce a 911 to check for shocks, doesn't work that way on 911s, IMO.

How does your car handle? Does the front feel stiff over bumps. Stock torsions?

Stock green Bilsteins in front and Sport yellows in the rear sounds like a common set up.

[tobluforu]

Mine is the same way up front. In all honesty, I think boge up front worked better than the hd's I have in there now. But my car is also very low.

[sugarwood]

I have no reference point to answer "How does your car handle?" I like it. I enjoy the stiff suspension compared to my commuter car. It's nice and firm so the car doesn't feel like it's going to topple over in bumpy turns, but it's not "kidney crushing" like I've heard people describe sport bushings. On a one hour drive, I have no comfort issues whatsoever.

The tech guy is experienced, but I am learning that unless someone can give me some empirical measure or evidence of what is wrong, I can't put much weight into that voodoo feedback. "The rear seems a bit squirrely" ....."The front seems too stiff" I suppose these are subjective descriptions. On the flip side, the guy wasn't try to upsell me on frivolous work, so I do think he's being honest in whatever he's observing.

The stiff bumper test sounds normal enough, but I still plan a bushing refresh this year.

[suckho]

My front and rear shocks were completely done, but there was no bouncing if I pressed it down (by sitting on bumper). After removal, I tested each shock absorber and they were very loose and did not return at all. I don't believe bouncing is good measurement for these cars.. maybe on some (all?) american cars, but not these.

[sugarwood]

Isn't the entire point of a shock absorber to prevent bouncing?
If a car does not bounce with a bad shock, what is the purpose of the shock?

A shock absorber is also called a "damper".
Like when the spring compresses, it will overshoot back.
So, the damper controls the recoil.
If there is no uncontrolled recoil, then I don't see what the shock is supposed to do.

[Bill Verburg]

Originally Posted by sugarwood

Isn't the entire point of a shock absorber to prevent bouncing?
If a car does not bounce with a bad shock, what is the purpose of the shock?

A shock absorber is also called a "damper".
Like when the spring compresses, it will overshoot back.
So, the damper controls the recoil.
If there is no uncontrolled recoil, then I don't see what the shock is supposed to do.

The whole point of shocks is to control wheel motion, by absorbing energy from the unspung(moving) assembly. The KE of the unsprung assembly is converted to heat by passing oil through various orifices in the shock.

Bouncing isn't a particularly effective diagnostic tool.

green front is usually Bilstein HD, as someone mentioned look for the roll pin near the bottom of the strut
yellow rear is more likely Bilstein Sport

these are gas shocks that are very durable, one failure mode is a blown gas seal at the rod guide, usually but not always a dribble of oil will be seen around the chromed shock tube. The only way to test is to remove the shock and check that it still extends itself due to gas pressure after compression. More modern and expensive gas shocks will have a Schrader valve that a pressure gauge can be hooked up to.

[michael lang]

Originally Posted by Bill Verburg

Bouncing isn't a particularly effective diagnostic tool.
yellow rear is more likely Bilstein Sport

Both of these statements are 100% correct. I have Bilstein Sports on front & rear of my car and the rears are what color...yellow. When I first ordered them, I thought Pelican sent me the wrong ones because they when they arrived they were yellow but when I spoke with customer service, they explained the Sports were yellow so I got exactly what I wanted.
I have been a DE tech inspector on and off for several years, I don't perform an inspection on a vehicle's suspension based on "bounce", I am looking for fluid leaking at each one of the corners of the car and to make sure the bushings are not so dry rotted and cracking that they are coming out of their housing like the trailer arm for the rear mono balls or the spring plates. Plus I'm looking at the tires which will tell me if there are any suspension issues with a car and also inspected the ride height will also give you clues if anything is wrong.
There is absolutely nothing wrong with the way your car was inspected, the inspector was doing exactly what he is supposed to do. My suspicion is, there is nothing wrong with your car except maybe the shocks being unbalanced to compliment each other by the previous owner or the previous owner to that person or the guy before him. Point is, if there is no noise, no fluid leaking, car sits level from the left/right, front/rear there's probably nothing wrong with your car. Go have fun at your DE.

[RichardNew]

They did a bounce test? Seriously?

Shocks and struts are the last thing to change on your car.

"It’s critical that you get the spring package right before you start playing with shocks. Once you get the springs right you can start to tune the package with shock absorbers. Koni feels that you should utilize shocks and sway bars as tuning devices only after you get the spring package correct. You don’t start with shock absorbers. Koni suggests that you regard shock absorbers as a precision tool for that final handling correction."

With different brands on the front and rear you have an interesting situation. Here's a whole bunch on shock information.

Richard Newton