Boxer suspension upgrade

bjunc · Jun 9, 2025

sherpa23 said: ↑

fairly lengthy list for the internals during the major.
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Nice. What are you having done?

FerrariIcona · Jun 10, 2025

bjunc said: ↑

Hi all,

It's come up a little bit in some of my other project threads, so I figured I'd consolidate the conversation into a dedicated thread.

Basically, I'd like to make some non-intrusive improvements to the suspension. There's more body roll than I think there should be, the front floats a little too much, and there's maybe a bit too much understeer. None of these are major problems, but I do notice them and I think (hope) most of that can be addressed by swapping out the Konis with coilovers that have adjustable compression and rebound, as well as the ability to adjust the ride height (preload the springs). I have a feeling a stiffer front spring is part of the equation as well. I'm not looking to run low-profile tires or dramatically change suspension geometry. Reducing the fender gap in the rear would be great, but that's not really the main goal.

After doing some research, I mostly settled on Ohlins TTX 36 (not the race version that requires frequent rebuilding). I spoke with their US team, who answered a lot of my questions, and then suggested I work with PSi in Sonoma California who has a lot of experience working with Koni, Ohlins, and Ferraris.

Packaging reasons might mean going with the inline version (ILX 36), or maybe remote reservoirs, etc.. After we come up with a theoretical setup, they'll ship me "dry" versions for mockup before building the final versions. The whole process will likely take a few months, so I'll post here as progress is made.

Fun fact, PSi actually works on Sammy Hagar's black boxer (which he still has). Apparently, Sammy wanted the car lowered; which PSi did the work (but recommended against). This really messed with the suspension geometry and Sammy had them change it back. I get the sense that 0.5" lowering is fine, but after an inch or so, things start to get messed up and would require a lot more work.

Lastly, PSi mentioned that the Konis can actually be modified quite a bit. I've seen others convert their Konis to height adjustable (eg Carobu), but I think you can even make the damping externally adjustable as well (PITA to adjust otherwise). That might be a Plan-B if things don't work out with the Ohlins.
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My Konis are modified with threading and BBi is lowered to where she should be. Drives great and takes bumps better than some more modern Ferrari.

sherpa23 · Jun 12, 2025

bjunc said: ↑

Nice. What are you having done?
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I sent you a pm.

bjunc · Jul 7, 2025 at 8:02 PM

Status update.

The new shocks are almost finished. We're just waiting for springs (Eibach). I should be getting all shocks ready for install in the next two weeks. I'm also working on an at-home alignment setup; which won't be ready for another few weeks. Unless I get antsy, I'll likely end up waiting to install the shocks until I can do a proper setup since I'm sure the new shocks and ride height change are going to mess with things.

Attached are a few pics of a front shock. PSi painted the new top eye extension in Koni orange.

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bamaman · Jul 10, 2025 at 8:16 AM

boxerman said: ↑

A cobra has a lot of weight in the front and a pretty unladen rear, so the rear will let go long before prob due to power and be easier to gather up. Front engine cars can do lurid controlled slides, you don't see that too often in mid engine cars, and even then only on modern ones with systems to prevent it all getting too far. Stands to reason with all the mass centred once rotation starts harder to stop, more like a spinning top thana pendulum, thats part of what makes a me car such a fast turn in handler and better able to use the max of all 4 tires but so hard to gather up. the worst imno are modern audis where the a fair bit of the engine sits in front of the front axle, of sourse when a bend comes the heavy part of the car wants to then keep going straight, so they use massive width front tires and electronics, most anything can be made to work even if not ideal. And boxers despite that heavy crankshaft sitting up high and less than mnodern suspesion geometry can be made to work way way better.

yes you can save a boxer esp with modern rubber and some nice rear width. Boxers are also cars that talk to you esp from the front end, so yes you can and should flirt with its limits. the caveat is the rear, doesn't talk nearly much and when it shouts mama mia then its oy vey.

Im curious where in FL we can find any roads to flirt with these limits, besides the odd 3000 degree onramp. I hear up by Ocala somewhere, and there is anew private track being built near ft pierce

i posted here years ago the driving impression at good wood on Nick masons BBLM. A BBLM is basically a reclothed lightened boxer with more hp, the suspension and fame really pretty much the same as a road car. It was faster around goodwood than Nicks F40 on the same day, we know a F40 is lighter and Hp between the two prob similar.
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I woke my neighbors an drove ex LeMans #70 BBLM #38179 on the roads in LA (lower Alabama) for a few blasts around town. I agree that it was similar to the road car. However, being lighter with the wider tires and more power, at non racing speeds it was a bit wide as it trundled along. among traffic making wonderful sounds. As a lawyer who knew lots of judges, I am glad I never had to explain the need to drive it on the street.

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