johnnydiii

Hi. We are contemplating a Boxster track car project. Really need only the shell and there are a lot of very cheaper older Boxsters out there to use as a starting point. I have searched the web a lot but have not found very good answers as to the differences in track and wheel base between the various model years. I get the impression that the track was widened in the mid 2000s but I can't find anything that says that the wheelbase has changed other than in the new 2013 Boxster. My questions are these:

1. Are the suspension attachment points the same for all model years up to and including 2012?

2. Since we are going to to be modifying this car heavily, can all the trick GT3 control arm and drop link mods be made to any model year Boxster from 1st gen to MY 2012?

3. Are the attachment points on the chassis the same for mounting of all the transmissions? We intend to use a 2005-on Boxster S 6 speed transmission in the build. Related, anybody know if all 6 speed trannys are the same regardless of whether they were in the S or not? Were there any changes to the internals on the transmissions? We want the stoutest 6 speed that is available.

I really appreciate any information that the group can provide. Thanks!

gfl

I think it is "yes" to all the above.

Grant

DOUGLAP1

In 1998, Porsche added some reinforcement in the rear monocoque structure, which was supposedly required to allow running 18" wheels. Other than that there is absolutely no difference that I can tell in any 986 or 987 Boxster or Cayman suspension.

Yes you can run GT3 LCA's on front and rear of any of these cars, though you really only need them on the front. For the money, I would go with the RSS version as they are completly solid bearings, whereas the real GT3 unit has rubber bushings. The only downside is that the RSS units are subject to more shock loading due to the lack of rubber, so the heavily stressed upright attachment bolt should be changed each year.

As far as the gearbox, I believe all 6 speeds are identical to the 911 6 speed. This is not really a good thing, as there are two inherent problems: 1- The gearing of the 6 speed is really too tall unless you have over 300 ft-lb of torque. Heck this thing does 74 MPH in 2 nd gear, and you never can use 6th on any normal race track. and 2- The 6 speed is dimensionally longer than the 5 speed from the bell housing to the differential output shafts. This means that the CV joints are always "working" with the half shafts angled toward the front of the car. I believe this is the root cause of why these cars are unusually hard on CV joints and rear wheel bearings.

There is a guy in Finland who is running a 986S with a 5 speed gearbox from an earlier car, so it is proven, and I believe would be faster for a pure race car. Go over to 986forums and look for "Kroggers" in the Comeptition section.

Paul 996

All of the 987 chassis 6 speeds from 2005+ are the same. Those years have much better gearing as well.

gfl

... from 1997-2012 have exactly the same control arms and thus mounting points. If the track changed, it is minor. All can thus use the GT-3 adjustable control arms, etc.

Grant

Paul 996

If it isn't clear I am referring specifically to the 6 speed transmission itself.

For the record the 986s and 987s have different front control arms and front trailing arms.

gfl

.... the rears are the same as 986, and the fronts show a different part number. Yet the look identical, and from what i have been told, are interchangeable. I'd need to see two side by side. The rears are certainly the same - part # and all.

Grant

N0tt0N

At the risk of raising an older thread, if the front LCAs are identical why does RSS have different 986 (356s - non-hydraulic thrust bearings) and 987 (361s - hydraulic thrust bearings) versions? What are hydraulic thrust bearings anyway? I can't seem to find the term in searches - at least for LCAs.

gfl

See above - fronts are different, rears are same

G

N0tt0N

Spoke to the excellent folks at RSS. They use the Porsche terminology (non-hydraulic vs hydraulic) which they understand can be confusing as their part does not have a hydraulic thrust bushing. As pointing out there is a fitment difference between the fronts of the 986 and 987 with the 987 being taller. Good news is that the difference between the 356s and the 361s is the bushing piece which can be purchased separately as part 318. $200 vs. $1000.

Excellent customer and technical support from RSS. Thanks!

sjfehr

I was mistakenly sent a 997 GT3 front sway bar for my 986, and can confirm it does not fit an otherwise stock 986 front suspension. So, there are some differences.

Turb-OH Brad

GT3 front sway bars require GT3 drop links. With the correct drop links, a GT3 front bar will fit all 986, 987, 996, and 997.

sjfehr

The 997 GT3 sway bar (997 343 701 95) will not fit a 986; the nub-to-nub dimension is about an inch longer and the bushings won't fit the brackets. You have to use a 996 GT3 bar on 986/996 and a 997 bar on 987/997.

The out-of-frame bushings are aligned; this is the offset between the stock 986 bar on the left and 997 GT3 bar on the right. I don't have a photo of the 996 GT3 bar, but it matches the 986 stock bar bushing locations.