Bilstein shocks---B6 series or AK series???

Anthony P

Active Member
#1
doing some research and reading. the part #'s have been updated. the old part #'s F4B...translate to the B6 series today. reading about them on Summit here, I find there is the B6 series and an AK series. there must be some difference in the valving. anyone know specifically what?

lots of old threads talking about the HD B6 series is the choice to make. but i don't believe the AK series was around in 2009. not really a cost difference. just curious about either series on a stock suspension, street car.
 
#2
The AK series is indeed new.
Bilstein's promo materials indicate it's a race shock designed specifically for series where the dampers must be affixed to factory attachment points. That could mean anything, but likely points to higher quality internal parts as opposed to magic racing damping curves.

It could be a better B6, but I can't find specifics on valving or construction. You'd have to ask Bilstein directly.
 

Anthony P

Active Member
#4
Thanks @Turbo6inKY for the info and pdf. from the pdf and your note, I'm thinking the AK series may be spec'd for road race circuit like IMSA meeting the installation qualification of the governing/sanctioning body.

while summit does not really specify a difference between the two series and cost is similar (B6 are $69 each, AK are $59 each), on RockAuto, the classification and pricing of the AK series is drastically different.

RockAuto has the AK series grouped as "original ride quality" with pricing at: front $108; rear $103 per unit. B6 series are grouped as "increased handling/performance" and are priced about $66 each.

Info on the B6 from RockAuto...

B6 Performance; For Stock Ride Height

Bilstein B6 Performance dampers are a performance upgrade to OE dampers designed to be paired with the OE factory spring.


Now I have enough info to carry an intelligent conversation with Bilstein tomorrow. I'll post what I learn.
 
#5
Thanks @Turbo6inKY for the info and pdf. from the pdf and your note, I'm thinking the AK series may be spec'd for road race circuit like IMSA meeting the installation qualification of the governing/sanctioning body.

while summit does not really specify a difference between the two series and cost is similar (B6 are $69 each, AK are $59 each), on RockAuto, the classification and pricing of the AK series is drastically different.

RockAuto has the AK series grouped as "original ride quality" with pricing at: front $108; rear $103 per unit. B6 series are grouped as "increased handling/performance" and are priced about $66 each.

Info on the B6 from RockAuto...

B6 Performance; For Stock Ride Height

Bilstein B6 Performance dampers are a performance upgrade to OE dampers designed to be paired with the OE factory spring.

Now I have enough info to carry an intelligent conversation with Bilstein tomorrow. I'll post what I learn.

That AK series may also be valved assuming a lighter-than-street-trim car. Most race cars are pretty stripped. Taking 1000 pounds off the chassis would definitely require different valving.

But that's just me speculating. Bilstein will have the answer when you call them. Report back what they tell you!
 

Anthony P

Active Member
#7
Hi John, good catch. been reading through a bunch of literature this morning and called Bilstein. Rep discussed...

for our cars, the B6 series shocks are still the prime choice and continue to have the lifetime warranty.

The AK series is a spec shock for circle track racing (dirt or paved) or autocross circuits (SCCA, etc). The valving is looser so as to permit the front to rise and rear to squat when accelerating out of turns, etc. Warranty is only 90 days for the AK series.
 
#8
Hi John, good catch. been reading through a bunch of literature this morning and called Bilstein. Rep discussed...

for our cars, the B6 series shocks are still the prime choice and continue to have the lifetime warranty.

The AK series is a spec shock for circle track racing (dirt or paved) or autocross circuits (SCCA, etc). The valving is looser so as to permit the front to rise and rear to squat when accelerating out of turns, etc. Warranty is only 90 days for the AK series.
If the AK valving is as stated, don't get them.
I'm already packing the front tires coming out of turns with the B6s. The AKs would make that even worse.
 

b4black

Well-Known Member
#10
Side note - the front Bilsteins come new bolts for the lower mounts. The are standard, but the speed nuts on the control arms are metric. You can force them to work, but better off going the hardware store and getting the right bolts.
 

~JM~

Wrinkled Member
#12
Side note - the front Bilsteins come new bolts for the lower mounts. The are standard, but the speed nuts on the control arms are metric. You can force them to work, but better off going the hardware store and getting the right bolts.
The original shock mount bolts can be re-used. You should probably put some anti-seize on them. Be gentle, the original speed nuts break easily. Don't try to force the Bilstein supplied bolts. You will most likely break the speed nut. Then its grinder & chisel time.
 

Anthony P

Active Member
#13
thanks @~JM~, been cleaning up various small batches of hardware and restoring the phosphate finish using Palmetto Enterprises solutions. really won't know what I will reuse until I get elbow deep into the job. sometimes it is easier to clean, Evap-o-rust and/or glass bead and boil hardware while other times it's easier to just buy a pack of 5, 10, 25, or 50.
 

Anthony P

Active Member
#15
@~JM~, wow that was a process. Reminded me of similar pain doing the shocks on my '83 Cutlass Supreme back in 1988. The top fasteners for the rear shocks were just a rusted mess. So I had a muffler shop take a torch to those fasteners. The mechanic suggested when I get to the front shocks, it's easiest to just use a long extension and break-off the top. I read someone suggested that in your thread. The bottom fasteners were not a problem - just a spray of penetrating oil the day before. They spun off no problem and were cleaned up and re-installed.

For the GN, this shock work should be no problem. The old yellow Monroe Gas-matics installed in 1992 only have 4467 miles on them and the hardware still looks new.