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Discussion Starter · #1 · (Edited)
Hey guys, I've found some good low-cost mods for a Boxster that's really worthwhile if you're sensitive to chassis flex. This doesn't really improve performance, even though a lot of aftermarket companies might claim so. However, for someone like myself who hates the little bit of "reverb" vibration emanating through the car's structure over rough roads or even normal bumps, this is great couple of mods. It does increase steering precision at very high g loads as well, but it's a minor difference.

So onto the mods. For the 987 chassis, Porsche decided not to include the diagonal braces in the front compartment that the 997s have.



The mounting holes for these braces are already in place in the 987, you only need to buy the braces and the 6 bolts for this to bolt right on.

Parts:
99650423301 (DRIVER SIDE)
99650423401 (PASSENGER SIDE)
90037810001 Hexagon-Head Bolt M10 X 45 2
90007501003 Hexagon-Head Bolt M6 X 12 4

If you're on a budget, go ahead and buy the braces used on Ebay or something, otherwise they're still only $130 USD or so. The bolts can be bought anywhere or ordered through a dealer as well. These braces will slightly improve steering precision when the suspension is loaded up in corners. The difference isn't huge, but it does work. Why Porsche left them off the 987, I have no idea.

The next mod is a lower suspension brace. This one made a fairly noticeable difference in reducing overall chassis structural vibrations over bumps. And luckily it is also extremely cheap to make.



It is basically the $100 Techno brace from Pedro's garage.

Parts:
One 24" 0.75" square aluminum bar
Two M10x55mm bolts with 1.5 pitch treads (could sub for M10x50 or M10x60)
Two 10mm washers

Cost will be below $20. What you need to do is undo 1 sway bar mount under the car, undo the 2 nuts on the most rearward (towards the back of the car) mounting point of the rear suspension. Pound out the studs that the nuts were screwed onto. Insert the aluminum bar and slot it right above where the 2 studs used to be. Mark the holes onto the bar by using marker or spray paint, take the bar out, drill out the holes (10mm diameter, 3/8 drill bits will get it really close, 3/8" = 9.6mm). Insert the new M10x50mm bolts and push the washer between the bar and the bolt head, and use the original nuts to tighten the bar onto the car (48ft/lb). Reinstall the sway bar mount (17ft/lb for the 2 bolts) and you're done.

This reduced chassis vibration/reverb by a good 75%, I'm actually amazed Porsche didn't reinforce the aluminum plate which mounts onto the same bolt holes, it's a missed opportunity to make the car feel much more solid.

I also bought an aftermarket front and rear strut tower braces for my 987 Boxster S, however I think the Porsche OEM front diagonal braces will be enough for the front, and the rear one didn't do much at all, plus it was very difficult to fit a 986 rear strut brace in a 987, I wouldn't recommend it.

The overall feel of the car is now much closer to a coupe than before. I never thought the Boxster lacked much in terms of out right grip in the corners, but the steering precision was just a touch off when you're cornering right at the limit, now that's much better. The best part is that a lot of the squeaks and rattles are gone, and the ride overall just feels calmer. A lot of the bumps on the road used to make the structure of the car reverb just a tiny bit, making it feel a bit busy. Now it is more solid and "refined" if you will.

As for the 987 Cayman, it already has a top, so I doubt these braces will make much of a difference. That said, how can you go wrong for less than $100 in parts for these braces?

-Lucas
 

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I use the Pedro bar on my 2007 Cayman S and it really really improves steering feel and cornering on both normal roads and track (Sebring). It has been the best mod I ever installed on any car I modded!
 

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Thank you OP! Do you have pictures of the installed diagonal braces in the front? I can see the mounting holes on the firewall which would require removing of the plastic cowl trim but after a quick look it wasn't obvious where the other end mounts to.
Thanks in advance...
 

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Confirmed that front diagonal brace does NOT fit a 987.1 Cayman. The attachment point on the firewall is present but the bolt holes on the strut towers are not there. Best picture I can find showing the attachment points is this one: Strut tower brace - 2 point - Front-Rennline, Inc.

If anyone is interested in the front brace (left/right diagonals and all bolts specified in the first post), PM and I’ll give a good deal. Since it was a special order item I don’t think I’ll be able to return them.
 
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