Modern trailing arms for the 914?, 986 carriers/calipers/e-brake, more adjustability, more tire? |
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Modern trailing arms for the 914?, 986 carriers/calipers/e-brake, more adjustability, more tire? |
horizontally-opposed |
Jan 26 2021, 12:21 PM
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#1
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Advanced Member Group: Members Posts: 3,431 Joined: 12-May 04 From: San Francisco Member No.: 2,058 Region Association: None |
I've been reviewing past discussions on these (links below) off and on, having test fit a 215/60R15 Pirelli P6000 on a 911R wheel into both rear fenders of my narrow-body 914. It seems doable, but it's going to take some massaging on the outer fender, custom spacers, and—maybe—narrowed trailing arms. Which got me to thinking about the current state of the 914 trailing arm, which is the same it's been since 1970.
Basically, those heavy, non-adjustable steel trailing arms are one of the very few things on the 914 that hasn't been addressed or evolved by the aftermarket. I'm running PMB-rebuilt trailing arms with PMB-rebuilt calipers, and can redo them again with reinforcements and/or some reshaping, but I wonder how hard would it be to do blade-type trailing arms of similar strength with less weight and/or more adjustment. Could a 911 spring plate, or a triangulated or otherwise reinforced version of it, be adapted? Looking at the basic design of the 914 arm, it doesn't look all that complicated, but I'm no engineer. EDIT: Possible use of a machined 986 wheel carrier, an aluminum casting by Brembo that incorporates the 986 e-brake and 986 four-piston caliper mounts, comes up later—a very interesting idea from @Chris914n6, particularly as the castings are available for $100-200ea used or new from Porsche. Bolting that carrier to a new steel trailing arm with a lower damper mount seems viable to me, but here to learn. The custom work to narrow factory 914 trailing arms looks extensive, but has been done by both @914timo and @sixnotfour as well as, it looks like, Rich Johnson. I could see doing it in the process of moving to 911 e-brakes and 986 2.5 brakes, maybe, but I wonder if a group buy might attract a 914 vendor we all want to support? Relevant threads: http://www.914world.com/bbs2/index.php?sho...p;#entry1247827 http://www.914world.com/bbs2/index.php?sho...ailing&st=0 http://www.914world.com/bbs2/index.php?sho...238144&st=0 http://www.914world.com/bbs2/index.php?sho...234391&st=0 |
horizontally-opposed |
Jan 26 2021, 08:08 PM
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#2
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Advanced Member Group: Members Posts: 3,431 Joined: 12-May 04 From: San Francisco Member No.: 2,058 Region Association: None |
^ Several people have narrowed the trailing arms. I've had 205/60s and 205/55s in my stock rear fenders over the years with no issue. Others have gone up to 225/50R16 or 225/50R15 in stock fenders "with a bit of work." That work has varied. There are a number of threads.
215/60s are hardly "balloons," as that's the factory aspect ratio/overall diameter for all 15-inch applications. I happen to love the bulging sidewall with 215/60—but it's a matter of taste as 50- or 45-series rubber looks incorrect on these old cars. Again, a matter of taste/preference. Agree on dynamic clearance, and well aware of that phenomenon, but feel that can be dealt with on the fender side and a wheel spacer. Trailing arm/brake line clearance was a bigger problem when I did the test fit, so it would be good to address it. Trailing arm question came after reviewing threads of others' experiences in sneaking more rubber into a narrow body car. Many of them narrowed the trailing arms, particularly with wheels that tuck the tire inward with the 911R offset (my preference), which I believe is preferable as an offset to a standard 15x7 Fuchs—both technically and visually. Finally, trailing arm question is prompted by the idea of paying for a second round of work on my trailing arms. By the time you narrow a pair, adapt 911 e-brakes, add new bearings, etc, one begins to wonder if you want the same old boat anchor—and if you're alone. Curious if Dave Darling remembers who built/offered/canceled the blade type arms with camber/toe adjustment at the rear of the arms. Unsprung weight is always nice to get rid of, too—and I know several people building 914s that might be able to justify a better option for the rear arms. Perhaps the economics/demand is different now than it was then—but the hours involved in reworking old trailing arms may help offset the cost of something better. The right design should have merit regardless of what wheels are used. If it provides more tire clearance on the inside, well, that's a boon. |
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