I've read a ton of threads about this but I haven't seen much actual daily driver feedback on the current
B6 front B8 rear offering for the early C4's? I know they aren't ideal, I know they aren't valved the same as
my original Z51 ones were (that I don't have fronts of anyway). I know there are better adjustable options
available but I don't want to get into all that if I can help it.

But do they actually work alright-enough for spirited and normal street use? Not hard as a rock, not bouncing up and down, not porpoising
front/rear, etc, etc?

I currently have original Delco Bilstein's on the rear and some black body made in USA generic ones on the front.
They really aren't *that* bad all in all tbh, the rear will bounce once now and then over dips, but I really don't have
much to compare them to on this chassis. I'm still in the shakedown/getting to know you phase so I haven't driven the car hard enough
to see if it does anything dumb but so far it's behaved about as expected.

Shame Koni does not have any coverage for these.
When in doubt I usually just buy KYB and have had good service from them on a number of
vehicles but none of them were sprung as tightly as this one, and I don't think they are
all made in Japan anymore either so who knows what's up with them. Boge/Sachs used to make
good dampers too but that isn't a given at all anymore either.

ETA: 5892ST on the fronts now which seem to be Monroe OE Spectrum, which I've used in the distant past and considered squishy garbage. Maybe these things just aren't picky about shocks if you aren't pushing them really hard?

 

long story short if u want a stiffer ride (usually associated with higher performance driving): if u plan on lowering, get a b8 AND if u are sticking with factory ride height, get the b6.

however if u want the base-ish shocks, so not the z51, get the b4.



I think that the closest replacement we can get to z51 is the b6. And a lowered z51 would be b8.

https://www.facebook.com/midasgarage...40aB7S9Ucbxw6v



for myself, b8 all the way. unless its on my daughters el cheapo 84, i went monroe sensitracks that were cheap as chips. the bilsteins are awesome. i wish i could tone down the rebound slightly but not bad enough that id bother with dual adjustable. cheers.

 

Are the B4 even an option? Bil USA didn't list them.
I'm a daily driver on BAD Oklahoma roads, like omg who built this garbage and thought it was alright to drive on bad.

 

Just replaced the Bilsteins on my non Z51 96 LT4. This is a sunny day cruiser that I open up once in a while. No track days. Thus I replaced with the softer option, can't recall if that's the B6 or B8. The original shocks weren't blown but I've noticed a huge improvement in ride quality.

 

Bilstein seems to indicate that one should be using a B6 on the front regardless of the suspension option (and it's all they offer) and they specify the B8 for a Z51 rear.
That's mostly what I was curious about, having the stiffer one on the rear. I know these are kind of a one size fits all damper now vs the originals.

 

I put the B8's at all 4 corners of my "relatively soft" 96' LT4, and they are fantastic.

 

B8 isn't offered for the front of early cars unless I'm missing something.

 

​​​​​​If nothing is changed and your car has the Z51 option, go for new Z51 bilstein shocks. The shocks are designed to the spring rate, so unless changing springs do not change to a base bilstein shock.
The springs / shocks have been designed to compliment each other for a particular purpose, if you want a more comfortable ride you should change springs and shocks to base.

If you want to improve the handling for track use dual adjustable coilovers are the way to go, however be warned get support brackets to distribute the load on rear shock mount. Have seen a few break the aluminum lower bolt mount of the rear suspension knuckle. There are some aftermarket metal brackets available that support the load on the shock mount, that bolts to the upper lower trailing arm mounts on rear suspension knuckle.

Of course I would recommend new front rear suspension bushes, the old rubber ones wear and that wear can only be seen once disassembled.

Cheers
Gerard

 

I replaced the KYB's that were on my '84 Z-51 when I bought it with B6 front and B8 rear. The B8 rear is all about rebound control since the stiff spring takes care of compression. My impression is that there is no more of the bouncy feeling in the back but the front feels a little "floaty" for lack of a better description. Perfectly fine for cruising. Hitting a big depression at the end of a bridge is one smooth motion.

 

There are no new Z51 Bilstein shocks available for an 86. You can currently buy what may or may not be a correctly valved B6 for the front and a B6 or B8 for the rear.
That's it.
If you could buy stock Delco Bilstein's that were correct for the car/suspension they'd be in the mail by now.

I am suspicious of putting a B6 on the front and B8 on the rear as Bilstein suggests for a Z51 car unless someone with experience can give me some assurance that it's by design.
I'm concerned that a B6 rear may not damp the Z51 spring rate sufficiently as well.
I have been in the auto parts business long enough to know that ANY manufacturer will quite being as attentive to details as they should once sales figures drop below
a certain point, and apparently shocks for a C4 are below that point now. Koni doesn't even bother and they are my preference in general.

I have an XJS with KYB Gas-A-Just on it (all six) that has held up well for 30K or so and deals with the roads around here quite well but that is a 400lb heavier car with much softer
springs and a suspension system pretty famous for good ride quality while still hanging into fast corners so I don't know that it's a fair comparison.
I've run Bilstein HD's on Mercedes and Volvo's and been happy with them but they both had a lot more leeway for daily rough road use than the C4 does.
It's really not intolerable now tbh, better than I expected a z51 car to be, but having mismatched dampers bothers me and I can't help but wonder if there are gains
to be had in either ride quality or handling dynamics, or both.

 

I've read that before about the increased rebound for the rear of the Z51 spring, my originals (150K) will now and then bounce once on the right kind of dip in the road that I assume is from wear/age.
I know your springs are a lot stiffer than mine being an 84, you're ok with the B6/B8 for general use though? I'm not a track guy, just bombing around on the street and into corners harder than I should
now and then. The B6 can't be any worse than whatever generic AC Delco or Monroe or whatever is on the thing now I wouldn't think.

 

There's no question the ride is stiff, but it's period correct which I like and the combo of Bilsteins and Toyo RA-1's makes it a cornering dynamo. My wife loves cruising in it but I get a mild rebuke if I take corners too fast for her taste.

Overall I am quite happy for cruising around on back roads. I'll seek those roads out as I hate the freeway and the car does a bit of tramlining in the ruts.

 

Thanks for the info.


Oddly my motley old 86 is really good on the interstate. I really expected it to be a lot worse all in all than it is. I hadn't been in one in 25 years when I bought it.
It's pretty well behaved all in all given what I make it drive over here.

 

Bilsteins are high quality monotube shocks, but they tend to ride pretty harshly. If Koni isn't making shocks for the early C4s, then Ridetech is, and think those are better than Konis anyway (they are quality monotube Fox dampers). They are also adjustable for rebound, and unlike the Koni rears, the adjustment ***** are easy to access without taking anything apart. You'll be able to get a better ride for street use when desired, and you can stiffen them up for more spirted driving needs. After Dark Speed might also have a good solution in their Viking line.

 

I had the new 1986 Z51 Bilstein fronts on my shock dyno as I thought it worked very well with the OEM 1986 Z51 leafs. Rebound would not control the 1984 Z51 front spring as well, and the compression would feel stiffer.
Best way to go is to get some Viking double or triple adjustable shocks only, and it can get to a coilover for not much money later on. Or Ridetech, they are good quality, but don't necessarily have the coilover acme threads. Or QA1 double adj for a cheap twin tube.

Match the rebound curve to the spring wheel rates as a starting point and most good shocks will come with a force/velocity curves... much easier said than done of course, but that's what I do.

 

If I buy adjustable shocks I'll spend the next six months adjusting them and making spreadsheets and just generally driving myself crazy so I'd really rather not, and most of those are way more money
and quality than a 150K miles daily driver (and me as a driver) is worth.


I ordered the B6 front/B8 rear setup for $404.39 shipped which seems pretty reasonable. I'll report back how they are. I think if this car was not a Z51 option I'd have just bought the
KYB's for half the price. We'll see I guess.

Near as I can tell from googling, when the Fg3 option came alone they had Bilstein's on non z51 cars, and the z51 cars had the same front shock but a different rear.
Maybe that's what Bilstein is currently going for with the B6 front/B8 rear deal. Being that I'm not totally turned off by 150K originals on the rear and whatever
Monroe on the front maybe I'm just not too picky on these cars, or I don't know any better. Ignorance is in fact sometimes bliss lol...