PSA: Turner J Stock Springs are Available Again

[moatilliatta]

Group N dampers are too stiff for Jstock springs.

[ForcedFirebird]

So spill the beans.

[Digitalwave]

Group N dampers are too stiff for Jstock springs.

Maybe that is true, but the Turner J-Stock dampers were the same valving as Group N (300/300 front and 200/200 rear).

[craz azn]

Maybe that is true, but the Turner J-Stock dampers were the same valving as Group N (300/300 front and 200/200 rear).

I think J Stock is softer, at least in compression. Like, 300/175 or so. I can't remember what rears were offhand.

[Digitalwave]

I did see someone else say that the shocks were 300/175 and 200/125, but I am not sure the source of that. On the other hand, here is a quote directly from Will Turner himself, taken from S14.net:

Me: "Do you think the springs will still perform well with normal B8's that are revalved and bump stops cut down? Not as good as your solution modifying the entire shock but I imagine it's better than nothing no?"

His response: "Yeah,

If you revalue the fronts to 300/300 or 300/200 and cut the bump stop they would be great… and revalve rears to 200/200"

Thread for reference: https://s14net.vbulletin.net/forum/s...rings-are-back

Now since the rates are derived from Group N rates, it makes sense that they used the Group N valving. HOWEVER, the J-Stock springs are progressive, so I could certainly see using less compression damping than the linear Group N coilover springs used.

[ForcedFirebird]

I have an alternative to the J stock rear inverted Bilsteins.

not inverted, 1/2 shorter, same valving if anyone is interested.

and

another shock inverted about the same length but with monoball bottom eyelet.

Still curious about this.

[craz azn]

I did see someone else say that the shocks were 300/175 and 200/125, but I am not sure the source of that. On the other hand, here is a quote directly from Will Turner himself, taken from S14.net:

[/B]

Thread for reference: https://s14net.vbulletin.net/forum/s...rings-are-back

Now since the rates are derived from Group N rates, it makes sense that they used the Group N valving. HOWEVER, the J-Stock springs are progressive, so I could certainly see using less compression damping than the linear Group N coilover springs used.

Here is an older thread where it was referenced on what J Stock is, which is remarkably similar to what techs at Bilstein also recommended back then. From personal account, I've driven a few E30s on-track, both with JS and Grp N dry setup shocks, and yes while similar, they are not the same. FWIW, I much preferred the J Stock spec shocks.

https://www.bimmerforums.com/forum/showthread.php?562920-Shock-Valving-How-to-read-it-and-what-springs-to-match

[BlackbirdM3]

I have a set of the J stock Bilsteins, the fronts seemed like they had WAY too much compression damping, the rears, under damped. I tried the rears on the car, I felt sea sick after one drive, so off they went. I went back to the TC Klein revalved Koni Sports. They have far less compression damping, but more rebound damping. The rebound damping is however a little higher (and adjustable). It makes the car perfectly balanced.

Will

[moatilliatta]

Still curious about this.

If wanting a set we can try and get a group by together so they would be at a reasonable price.

[TKuhl]

So I just finished installing a set of JStock springs and thought I'd share the results. This should give a good idea of what changes regarding stance since all I changed was the springs and pads.

original alignment numbers based in the most recent documented that are with the car,, dated 2013 so isn't it be perfect t but its all I got to go on.

car is a 1991 318is with original equipment, Koni Sport shocks that came with car when I bought it. Original springs with 266k miles

swap was new JStock springs,, same Koni dampers,, new 9mm and 3mm pads in front,, New thick stock pads in back plus 9.5mm condor spacers in back.

original measurments to center wheelarch were 25 3/8" front and 24 1/8 rear (forgot to measure to pinch weld)
with jstock it became 24 front and 23 3/8 rear, so essentially 1 1/4 inch front drop and 3/4 rear

Base of pinch weld now 6.5 front and 7.5 rear.

camber moved only about -.6 in front and -1 in rear which surprised me it seemed alot more than that.
toe moved -.04 in front and -.1 in rear these are based on old paperwork though...

I also learned the driver side sits about 1/4 inch lower than the right side both before and after spring swap.

[TKuhl]

I forgot to say, camber is now -1.5 on stock perches (I don't have adjustable plates yet)

[moatilliatta]

Thanks for the update.

Those shocks are way under dampened, will ride much better and handle better with a match set of shocks.

If its just mainly you and a half tank of gas, you can shuffle different spring pads around to help out with your ride height, Or maybe best on a set of scales if you're more interested in corner weights VS ride high matching.

Also, A sway bar causing preload may change these numbers.

I wish I knew what the difference between early and late rear fender gaps were.

[TKuhl]

I bet youre right,, i bugged Blackbird for advice and sort of following his setup... I bought the jstock bilsteins for the front, and planning to install them with vorshlag camber plates later this summer. I signed up for my first autoX this March so a couple events on current setup then a couple on the future setup should be good comparison. Currently it corners great over stock obviously, but its bouncy even with koni turned all the way -1/8 turn from full stiff.

Basically I'm just starting to get my feet wet with the racing stuff, so I'm doing my best to match all the interweb research with a tapemeasure. I think if this summer goes well and I get hooked (very likely) ill have to find a local shop to really dial in the corner balance etc.. at this point,, tape measure says i have 1" rake and my control arms are dead level so i think aside from the konis its about as good as can get it, on paper anyways...can't wait to try it all out!

[moatilliatta]

I found a shorter rear shock, but it’s not inverted. It’s not cheap. But it’s rebuildable and exactly to Jstock.

[Digitalwave]

GroupN Bilsteins for the rear are still available in the UK and aren't too expensive. I think I paid about $350 shipped for the pair. They are shorter than Bilstein Sports and have the same valving as the J-Stock Bilsteins did (200/200).