Modifying Bilstein Shocks

[Shankenstein]

As usual with my discussions, please pretend that budgets are infinite, safety concerns are non-existent, and nothing is impossible.

Some people have noticed that Bilstein shock absorbers have common components, serviceability, and straight-forward designs. To this end, it's been shown that off-the-shelf dampers can be converted to full-blown "take apart" motorsport dampers.

http://farnorthracing.com/shocks_2.html

MX-5 Forums:

It's very simple actually. Just drill a hole in the lower (conical) part of your damper. Place the hole where your future valve will be. The air would come out, so the pressure would be released. Then push down the upper cup little bit and take out the first (top) ring. That will release the upper cap to move up. Then, on some Bilsteins there is a lower ring too (under the cap). Remove that one too, so you can slide out the piston. And that is pretty much it.

Once everything is out, with a compressor apply pressure through the hole you made. Do point the damper down or somewhere safe as the separator will come out with a big "boom" and will fly away if the pressure is so high, etc. Then install the valve, clean inside very well, put back the oil separator and make sure it will never touch the piston when fully compressed, and will never go all the way to the bottom either. Ideally you want to put the separator as high as possible. If you do not want the valve and do not want a separator anymore, then put an external reservoir through that hole you made. Then put back the oil, slide the piston, put the lower ring, fill up all the way to that ring and little bit above, so when you put the upper cap the oil kind of spills out (so you make sure there is no air in there), then you put the upper ring and it is done. The last thing - through the valve you put down there, inflate with nitrogen. 200 PSI is about right. Hope this helps.

Evo X forums:
http://www.evolutionm.net/forums/evo...ml#post1964697


Question 1:
What platforms are available for our platform?

B6 & B8 would be cheap and simple... but with a limited selection of springs available.




B14 would have standard springs available and height adjustment.


B16 would add adjustable damping (if that's a good thing).



Question 2:
Is it better to build up from a universal motorsports damper?


Threaded lower mounts or weld-on brackets aren't rocket science. Then cut threads into the upper stub to match any of the lovely FRS/BRZ upper mounts on the market today (CasCam anyone?).


If you were going to DIY the ultimate damper, what would you do?

[Racecomp Engineering]

I know that first part says "It's very simple..." but I can't stress enough how not simple that whole process is.

Yes anyone can take a drill to their shocks with the right knowhow and commitment but its not a good idea for everyone. If you dont have a shock dyno then you're not revalving shocks on your own.

The B14 coilovers are IMO the proper starting point as its a shorter shock body. Just needs linear springs and depending on rates chosen a revalve too.

The universal motorsports shock (or MDS) is awesome. But a bit more upfront cost.

- Andy

[Shankenstein]

Originally Posted by Racecomp Engineering

I know that first part says "It's very simple..." but I can't stress enough how not simple that whole process is.

Yes anyone can take a drill to their shocks with the right knowhow and commitment but its not a good idea for everyone. If you dont have a shock dyno then you're not revalving shocks on your own.

The B14 coilovers are IMO the proper starting point as its a shorter shock body. Just needs linear springs and depending on rates chosen a revalve too.

The universal motorsports shock (or MDS) is awesome. But a bit more upfront cost.

- Andy

That was in a discussion among autocross/track superstars. Robispec and some SCCA champs were involved.

This is not for the bolt-on guys, but for those who value a take-apart shock without the price... I'm curious what the options are.

[M23]

Either...

Custom re-valve B8/B6 to match your springs (if you want it better/perfectly matched, than OTS B8/B6's). $420.

or

Get some Hyperco or Swift linear springs for your B14/B16 (with accompanying upper top perches and other small misc parts, helper springs perhaps, etc.). These springs and parts are relatively inexpensive.

RCE can help you out with either decision with their vast knowledge.

[Shankenstein]

Ran across some useful info on the Honda forums about a guy who built his own shock dyno and revalved his own shocks. Lots of cool tinkering, with pictures and explanations.

http://honda-tech.com/road-racing-au...oject-2415915/

I may not go that rogue... but modifying some B14's could be a fun project.

[Ro_Ja]

I would like to rebuild my B14s to use Hyperco springs, but I have no idea what rates to run. :\

[M23]

Originally Posted by Ro_Ja

I would like to rebuild my B14s to use Hyperco springs, but I have no idea what rates to run. :\

@Racecomp Engineering

[Ro_Ja]

Originally Posted by M23

@Racecomp Engineering

Yeah, I already tried posting in the RCE/CSG ask anything thread. I got no response.

[M23]

We've messaged each other before regarding conversion to linear springs. The only thing you need (aside from the hyperco/swift springs) would be custom upper spring perches for the narrower ID linear springs (since the B14/B16 reuses the oem stock upper perches/hats; which are wide/big/oem diameter on the top section of the spring (it tapers)). He also suggested using helper springs and helper spring separator. I forget which exact rates he recommended (I don't have that account anymore and cannot review my old messages); but, I think it was around the 6-7kg spring rate range for OTS valving. Of course, it would be best to re-valve them (at an additional $420 on top of the cost of new linear springs/perches/helpers/separators). You will also have to figure out what the best spring length to get is (you don't want to end up having the finished setup too high or too low; even with the range of adjustability).

[Racecomp Engineering]

I can give some better recommendations later on spring rates. Bear with me...

- Andy

[cdrazic93]

Originally Posted by Shankenstein

Ran across some useful info on the Honda forums about a guy who built his own shock dyno and revalved his own shocks. Lots of cool tinkering, with pictures and explanations.

http://honda-tech.com/road-racing-au...oject-2415915/

I may not go that rogue... but modifying some B14's could be a fun project.

Whatd you do in your spare time?

Oh you know, just built a shock dyno and revalved my own shocks, no biggie.

[Ro_Ja]

Originally Posted by M23

We've messaged each other before regarding conversion to linear springs. The only thing you need (aside from the hyperco/swift springs) would be custom upper spring perches for the narrower ID linear springs (since the B14/B16 reuses the oem stock upper perches/hats; which are wide/big/oem diameter on the top section of the spring (it tapers)). He also suggested using helper springs and helper spring separator. I forget which exact rates he recommended (I don't have that account anymore and cannot review my old messages); but, I think it was around the 6-7kg spring rate range for OTS valving. Of course, it would be best to re-valve them (at an additional $420 on top of the cost of new linear springs/perches/helpers/separators). You will also have to figure out what the best spring length to get is (you don't want to end up having the finished setup too high or too low; even with the range of adjustability).

Good to know. I have the HVT camber plates, so I can just order the perch piece that can convert to 2.25 springs. I can grab a pair of spring dividers, helpers, and main springs from my work. Do I need a solution for the rear? (Currently using OEM upper mounts)

Do you know what diameter the springs are on the B14? 2.5? Could I theoretically just get the same size in Hyperco and save myself the hassle with the upper mount? I don't really need the wheel/tire clearance the 2.25 offers. (Edit: Actually, this wouldn't work because the bottom of the spring tapers in on the lower spring perch, correct?)

[M23]

Originally Posted by Ro_Ja

(Edit: Actually, this wouldn't work because the bottom of the spring tapers in on the lower spring perch, correct?)

Exactly. Linear/swift/hyperco are straight up and down; whereas Bilstein are tapered, small on bottom and oem-big on top.

Actually, you don't need nice aftermarket camber top hats to convert or make this work (though of course it wouldn't hurt). You just need custom upper perches (which in turn, press/rest between the upper spring and oem top hats). Basically, it would be similar to how RCE T0 and T2 work with oem top hats. I've lost all my old messages with RCE about doing this; but it would be basically trying to make/transform the Bilstein coilovers into RCE linear coilovers.

[M23]

I did some simple cost calculations. And, I think you'd get the most bang for the buck by just getting RCE T0 or T2 (cheaper/same-price..and at the same time already built (no down time) and valved correctly).


RCE T0: $1700 (non-adj)
RCE T2: $2400 (2-way-adj)

vs

B14: $1100 (non-adj)
B16: $1900 (1-way-adj)

B14 Modded ($400 revalved, $400 springs/parts: appx +$800 total): $1900
B16 Modded (revalved/springs/parts: appx +$800 total): $2700


Even T0 would be the same price as a Tarmac/Spec-R + revalved B8/B6 setup:
Swift Spec-R or Tarmac: $375 or $330
B8 or B6 shocks: $900
Total: $1275
Revalved Total (+$420): $1695