Modifying Bilstein Shocks

[Racecomp Engineering]

Originally Posted by bholliday

Andy, have the the dyno plots for the Bilstein B14 been posted somewhere or, is that something you have done on your own equipment?

They have not been posted. I would have to ask Bilsteins permission to post and I'm not sure they want me to.

- Andy

[bholliday]

Thanks. I've been thinking about shock options and was just curious if I had missed it.

[Shankenstein]

Not sure if it's 100% accurate for the 86 platform, but for the Lexus GS, some guys were able to revalve BC Racing shocks using Bilstein 46mm parts.

http://www.clublexus.com/forums/gs-f...ml#post8860594

BC Racing coilovers include top hats, come with springs, and some include external reservoirs (if that's your bag). I'm sure their build quality isn't quite Penske-level, but this could be a really interesting option for some people.




Also, got in contact with a fellow who does alot of shock tuning (with a Rhoerig) in New England. Will update as things progress.

[Shankenstein]

Mildly interesting finds:
- Apex'i uses 44mm pistons.
- AST uses 44.5 and 50mm bodies for their inverted applications.
- Bilstein's standard pistons are 36mm and 46mm. No combinations like Penske, though
- Fortune Auto uses 50mm pistons.
- JIC uses 40mm pistons.
- JRZ appears to use 44mm pistons.
- KW uses 33mm pistons.
- Megan uses 44mm pistons.
- Neo Motorsport uses 25 mm for twin tube pistons.
- Ohlins's standard pistons are 25, 36, 40, and 46mm. They have some interesting designs
- Penske's standard pistons are 45mm and 55mm. They're gorgeous!
- Ridetech uses 46mm pistons
- Tein uses 22mm for twin tube pistons
- XYZ Racing uses 45mm pistons
- Zeal uses 38mm for B/B2, 42mm for B6/S6, and 45mm for SF series

Not sure how interchangeable anyone's parts are... but it's good to start learning which parts are easily available (read: Penske, Ohlins, and Bilstein).

[cdrazic93]

Quick question; what does piston size advertantly effect in the damper feel?

[Shankenstein]

Originally Posted by cdrazic93

Quick question; what does piston size advertantly effect in the damper feel?

Not an expert, by any means... but Pressure Difference * Area = Force.

Bigger pistons have more available area for generating the pressure differential. The pressure differential is still defined by:


Things get complicated, since area is a fuzzy concept here. It's an equivalent area, because some of it is resisting and some of it is flowing. Flow rate (Q) and density also start getting funny as you push towards higher Reynolds numbers (measure of turbulence). Shock oil is relatively incompressible, but if you crank up the pressure differential, the turbulence will cause the air suspended in your shock oil to cavitate/foam. When the fluid becomes compressible, the physics start breaking down and the shock becomes less effective.

Also, bigger piston diameters usually accompany bigger rod diameters, which can transmit the resisting force more easily.

[cdrazic93]

Total engineers answer to that question, lol I love it

[Shankenstein]

Originally Posted by cdrazic93

Total engineers answer to that question, lol I love it

[Shankenstein]

Quick update from the take-apart world.

Ballpark quotes for everyone!

Penskes = $7k for non-adjustable, $7.5 - 8k for double adjustable, $8.5 - 9k for triple
Bilstein MDS = $7k, bring your own springs

[Shankenstein]

Got confirmation from BC Racing about some interesting things:
- Their coilovers use 46mm pistons that can be substituted with Bilstein/Ohlins parts.
- They sell replacement parts so that your local suspension shop can revalve/rebuild using BC components.
- Their shop in Florida can build a set to spec, and service is pretty inexpensive.
- Parts are not peened or staked... just loctite on the shock nut.

It seems like the BC Racing ER series would make a fine platform for Frankendamper. The external reservoir would allow for easy depressurizing and re-pressurizing. The piston/shim options are endless, and spare parts are cheap.

With everything set to full hard, you can set the valving for autoX and track usage... then open the adjusters for street.

My main concern with BC is corrosion. Their "black chrome" coating on the threads is more likely to gum up, compared to Bilstein's 3-layer plating.

[Calum]

Originally Posted by Shankenstein

Got confirmation from BC Racing about some interesting things:
- Their coilovers use 46mm pistons that can be substituted with Bilstein/Ohlins parts.
- They sell replacement parts so that your local suspension shop can revalve/rebuild using BC components.
- Their shop in Florida can build a set to spec, and service is pretty inexpensive.
- Parts are not peened or staked... just loctite on the shock nut.

It seems like the BC Racing ER series would make a fine platform for Frankendamper. The external reservoir would allow for easy depressurizing and re-pressurizing. The piston/shim options are endless, and spare parts are cheap.

With everything set to full hard, you can set the valving for autoX and track usage... then open the adjusters for street.

My main concern with BC is corrosion. Their "black chrome" coating on the threads is more likely to gum up, compared to Bilstein's 3-layer plating.

For the potential price difference, just anti seize the hell out of them every few months. Or get a can of rustcheck and spray them down.

[cdrazic93]

Originally Posted by Shankenstein

Quick update from the take-apart world.

Ballpark quotes for everyone!

Penskes = $7k for non-adjustable, $7.5 - 8k for double adjustable, $8.5 - 9k for triple
Bilstein MDS = $7k, bring your own springs

Last time i checked the 7500 series double adjustable can be made for this platform with the addition of springs for ~$3200? Thats what i got from the Penske development thread.

[Shankenstein]

Originally Posted by cdrazic93

Last time i checked the 7500 series double adjustable can be made for this platform with the addition of springs for ~$3200? Thats what i got from the Penske development thread.

I put up the prices from my local Penske dealer. I'm guessing that includes shipping and some mark-up.

According to latest from ANZE, the prices for Penskes are: Link to PDF price sheet
- $4300 for single adjustable
- $5090 for dual adjustable (inline)
- $5905 for dual adjustable (ext res)
- $7415 for triple adjustable (ext res)

Ryan from Penske hinted that they would be based on the 7500, 8300, and 8760.

[cdrazic93]

Originally Posted by Shankenstein

Ryan from Penske hinted that they would be based on the 7500, 8300, and 8760.

Thats a huge mark up! Lol i wonder if they would be able to retro fit an 8765 in there? Because racecar.

That single adjustable from ANZE with Penske internals is a huge contender for the JRZ and MCS crowd.