GC New Technology Fronts and three Install DIY's

CSBM5 · Mar 18, 2007

Excellent information, especially the details of the new GC design potential front clearance issues with rears up front! Is there anything else that is changed with the red Konis? How about at the rear?

Thanks,
Chuck

CSBM5 · Mar 18, 2007

Wow, I just read your DIY write-ups, and that is a huge contribution to the board! Thanks for taking the time and effort required to document all of this work. You might want to edit your original post to include direct links to these articles.

I don't currently need the install info, but I sure can appreciate its value and the knowledge that this info is available for the future. There's nothing like having practical first-hand pointers available when you start a job like this one.

Cheers,
Chuck

Lscman · Mar 18, 2007

This writeup needs to reside in the dedicated E39 forum, instead of splitting the topic. The Tech Tips area mixes E39 with E60 which makes no sense bercause the two cars share almost no technology. Separate DIY/Tech Tip sections compete with popular model-specific sections and seldom function as intended.

Pics of the front shocks & resulting sidewall clearance would be very helpful.

I will try to withhold drawing "firm conclusions", until I see details about the system.

Questions come to mind. As we know, spacers between 4mm and 9mm do not maintain hub centricity and oversize spacers cause fender lip interference when running wider rear wheels up front with streetable camber setting:

Potential problems seem to have been created for folks running 9.5" rear wheels (hypothetical only):

-do the sleeve collars extend down into the tire sidewall bulge area?
-will 3mm spacers be adequate?
-fender lip clearance at full jounce with appropriate spacers??
-useable front ride height collar adjustment range??

Potential improvements seem to have been made for folks running 8" wheels (hypothetical only):

-approx 1/2" more jounce than stock
-approx 3/4" more jounce than Dinan
-lowest ride heights possible with 8" front wheels
-better handling with lower ride heights

If 9.5" wheels actually work with this new configuration, I'd love to hear it. Waiting.......

jaj Discussion starter · Mar 18, 2007

CSBM5

Thanks! I thought long and hard about tackling the job by myself, and having done it, I feel really good about it. When I had FSD's installed last year, I had the dealer do the work, and they did a great job, but it was expensive and the expense was an obstacle to any fine-tuning. I concluded that with all the issues around coil-overs and adjustments and so on, that being able to do it myself was a necessary part of the equation. It's nice to know that it's possible to do it solo, and if you do things in the right order, it's actually pretty easy.

Lscman

I'll have to find a decent camera and take some pictures. All the ones I've done so far have been pretty ho-hum, and it's the details that matter with this stuff.

The new style front dampers are a smaller, shorter Koni damper installed inside a machined GC strut tube. As with everything GC, it's a work of art. The assembly resembles what Koni calls a "wet kit", except the outer tube is a purpose-built unit made by GC for the E39 rather than a gutted stock damper.

I'm thinking about getting a pair of 10mm hubcentric spacers (H&R #2075740) to try with my 275's. They would provide about 8mm of inside clearance, and they might work ok outside if the camber's cranked up to 2 degrees or so. It'll be a case of trying it and seeing if it works.

As for your specific questions:

-do the sleeve collars extend down into the tire sidewall bulge area?

The lower perch can wind down that far, and if it did it would use 11mm of the available 19mm of clearance with 245's. The lower perch distance from the knuckle is determined by the spring length and rate combined with the ride height. I'm pleased to report that the damper body is long enough that the perch can be adjusted high enough to provide over 14 inches of front height, although not much more with 7" - 430# springs.

-will 3mm spacers be adequate?

I doubt it. I think you need 5 or 6mm at a minimum by calculation. I'll get around to measuring at some point.

-fender lip clearance at full jounce with appropriate spacers??

Excellent question - dunno yet.

-useable front ride height collar adjustment range??

I haven't explored this one at all - I was more focused on getting the job done and getting my 14" height.

Something I didn't mention in the first post is that I installed an Eibach 18mm rear bar as well. It will tend to bias the handling more toward oversteer so I'm thinking that I'll do my first DE this year with the 245 fronts. Once I know that the whole package is balanced and the car's not tail-happy, I'll turn my attention to the 275 fronts again.

Cheers
JJ

doug · Mar 18, 2007

This is good info-- thanks. I've been thinking of doing a GC setup as well.

As of this Spring I'll be running 275's w/ stock rims up front so I'd be very interested to hear more about your experiences. How'd you choose a spring rate, btw? Was 430/380 GC's suggestion?

Kin Mak · Mar 19, 2007

I was going to go for GC coilovers but due to the fact I hear the bottom out a lot and the fact that Irish roads are just full of potholes.

Also the fact you cannot adjust the rear rebound/compression without taking apart the rear just seems ridiculous. I don't see the point in having it adjustable when you really can't do it easily.

So until the new release comes out that allows adjustment of the rear by just jacking up the car my next coilover purchase will be Bilstein.

Great info on instaling the coilover tho.<O

</O

jaj Discussion starter · Mar 19, 2007

Doug

The 430F/380R combo is the Discovery Automotive setup. They posted it quite a while ago on this board, and they confirmed it again when I emailed them.

I went out and did some shopping this afternoon - some highway driving, some city, some dodging potholes in parking lots. The conclusion? Perfectly driveable just the way it is. No bottoming, either.

Kin

The adjustment of the rear is a pain if you need to do it. What you really want is the GC/Koni yellow front setup (which I believe is still available) with the Bilstein rear. That's a combo that's easily adjustable and gives you the most clearance at the front for wide tires.

Cheers
JJ

Redshift · Mar 19, 2007

Fantastic contribution, JJ. I've been waiting for more information to come out on the newer style Konis (and the top-adjustable rears as well) before I made the jump and upgraded my spring rates to something a little more stiff. You seem to be in the same position I was in back in '04 when I had one of the very first GC systems for an E39 M5 and had it installed right away and began tracking it.

Since then I've got some bottoming issues, even with a raised ride height, and my springs are just too soft for my tastes.

Once these issues work out down the road, I plan to do some upgrading, and thanks to your detailed DIYs, I may attempt them myself instead of having someone else do it.

Thank you for all your hard work.

Lscman · Mar 20, 2007

Kin Mak;999035........[COLOR=black said:
Also the fact you cannot adjust the rear rebound/compression without taking apart the rear just seems ridiculous. I don't see the point in having it adjustable when you really can't do it easily........

Dampers that are easy to adjust are generally counterproductive for street drivers. Adjustablility allows the damper to be calibrated for a specific setup, as each spring and chassis combo has an optimal damper setting. Koni Sport SA meets this criteria. Once dialed in, the damper setting should generally not be tweaked toward an underdampened or overdampened setting for any reason. The best practice is to set it right and forget it. The optimal Koni damper settings are known for various E39 spring rates, so there is little or no guessing involved. The rear E39 Sport dampers are set between 1/2T from full soft to 1-1/2 T from full soft, depending upon the spring chosen. Stiffer springs require more damping.

Here's a list of situations where adjustable dampers are actually useful:

-a racer with a detailed log book and many days of practice may have some luck pre-tuning dampers for certain conditions at a given track (rain, cold, warm etc). A unique setting that provides gains under particular conditions will result in losses under other condtions. Such a tweaked setup only works on a short closed track circuit, not street with varying condition.

-a racer with a detailed log book might be able to tweak dampers for a particular track. This would only be possible after measuring lap times for repeatability & tiny gains over many hours on a 2 mile closed circuit stretch of track.

-a racer with a log book might want to change springs for each track and reset the dampers to match the new springs. The struts on a BMW can not be pulled off in 10 minutes for spring replacement like a Corvette. This makes it tough and limited opportunities exist.

Here's a list of situations where adjustable dampers are nothing more than a silly toy:

-a street driver softens dampers beyond optimal setting without changing springs. This deteriorates handling and causes the car to heave and pogo as if it has worn out shocks. This is not more comfortable, just different. Handling is sub-par.

-a street driver stiffens dampers beyond optimal setting without changing springs. This deteriorates handling and causes the car to become unstable & unforgiving under aggressive transient meneuvers or poor traction conditions.

doug · Mar 20, 2007

Rick, again... thanks for helping to further demystify suspension tuning. cherrsagai

CSBM5 · Mar 20, 2007

It can and does get a bit more involved than above since in shock damping you are really dealing with two separate regions of performance: 0 to 2 in/sec or so which is the range of shock piston velocity that you can impart through the brakes, steering wheel and accelerator, and secondly, 2 in/sec and above piston velocities which is the range of velocities a shock sees when responding to pavement inputs -- and these can get pretty high, i.e. 15 in/sec..

Now add in rebound and compression on top of the above, so in a sense you create four zones of shock performance.

With a standard Koni for example, when you adjust it, you only effect the rebound damping curve. It moves the whole curve up and down on the chart (plot damping force on y-axis versus shock piston velocity on x-axis). On a double adjustable shock, you get to move the compression damping curve also. However, few shocks give you the option of adjusting the "low speed" damping range (driver input range) and the "high speed" range (road input range).

The tuning of that "driver input range" in both compression and rebound is where most of the meat is in working out the best handling shock response for a given spring/sway bar combo. How hard you make the compression damping directly relates to the transient behavior of the chassis since you create a dynamic additional spring rate in a sense. Blending that region with the high shock velocity zones creates the damping combo that "works" best.

When you really look into this stuff, you quickly realize that it is not just a simple "shock absorber" at all.

Heck, on top of just looking at shock velocity curves, if you then get into the shock piston acceleration curves and the derivative of acceleration (rate of change of acceleration), you start looking at an even deeper level of how to "tune" a shock absorber, and the problem complexity ratchets up yet another level.

Chuck

Lscman · Mar 21, 2007

CSBM5 said:
It can and does get a bit more involved than above since..................

When you really look into this stuff, you quickly realize that it is not just .........

Chuck

Indeed. The additional detail you provide is very significant & advantageous to experienced racers and/or teams who maintain detailed log books and have substantial technical skill.

My experience with amateur racers over the last 20+ years shows that only the top couple percent of drivers possess the sensitivity, skill and experience to independently optimize both rebound and compression settings. You need years of track tuner experience and lots of track "test and tune time" to properly calibrate DA's. The vast majority of drivers will tweak and twiddle settings totally out of whack. I watched the #1 USA Champion Solo II driver (with about 10 years experience) totally screw up a setup trying to adjust for weather conditions and a particular turn. An experienced techno wizard can occasionally find gains from a better quality DA damper such as Moton, that's been dialed in by someone with the necessary skill and track test time.

For most drivers, default compression settings are generally a safer bet than dual adjust. This is why SA dampers are so competitive in the SCCA, even when they are combined with springs that are almost triple the normal OEM spring rate.

Significant lap time gains on M5 will come from highly elevated spring rates with decent dampers. A DA premium damper combined with comfy aftermarket sport lowering springs is not the hot ticket.

If the M5 was well-supported in the aftermarket, we could have both....DA premium dampers combined with appropriate 500+# track springs. We need to choose a Corvette or similar to get that.

Need4Spd · Mar 20, 2007

When you really look into this stuff, you quickly realize that it is not just a simple "shock absorber" at all. Heck, on top of just looking at shock velocity curves, if you then get into the shock piston acceleration curves and the derivative of acceleration (rate of change of acceleration), you start looking at an even deeper level of how to "tune" a shock absorber, and the problem complexity ratchets up yet another level.

Yep. Totally agree. Which is why I decided that for my street ride, I'd leave the velocity curves to Koni. The FSD has at least two different curves, one for high velocity inputs (potholes, bumps), and one for low velocity (steady state banking, slalom).

Need4Spd · Mar 22, 2007

For most drivers, default compression settings are generally a safer bet than dual adjust.

This, of course, is why I went for the Koni FSDs on my street setup. No fiddling possible. Is it ideal? Probably not. But closer than I'll bet I'm capable of dialing in.

jaj Discussion starter · Apr 6, 2007

Update on Front Suspension Clearance w/275's

I just trial-fitted my 275 PS1's on stock rear rims on the front with the 3 mm spacer so I could measure the clearance between the back of the tire and the threaded adjustment cylinder. Recall I have the new technology GC front setup.

The measured clearance to the threaded sleeve is about 2 mm. I could put 0.090" of feeler gauge blades through the rubber-to-aluminum gap, but no more.

This is NOT ENOUGH clearance to run 275's on the front unless you use a wheel spacer thicker than 3mm. The thinnest hub-centric spacer is an H&R 10 mm product.

I've spoken to Jay about it, and there are a couple of solutions that might work. After I've called him back with the measurements next week, I'll pass on what I learned. One solution may make it possible to stop using the wheel spacer entirely - I hope it can actually be implemented.

Cheers
JJ

CSBM5 · Apr 6, 2007

jaj said:
I just trial-fitted my 275 PS1's on stock rear rims on the front with the 3 mm spacer so I could measure the clearance between the back of the tire and the threaded adjustment cylinder. Recall I have the new technology GC front setup.

The measured clearance to the threaded sleeve is about 2 mm. I could put 0.090" of feeler gauge blades through the rubber-to-aluminum gap, but no more.

This is NOT ENOUGH clearance to run 275's on the front unless you use a wheel spacer thicker than 3mm. The thinnest hub-centric spacer is an H&R 10 mm product.

I've spoken to Jay about it, and there are a couple of solutions that might work. After I've called him back with the measurements next week, I'll pass on what I learned. One solution may make it possible to stop using the wheel spacer entirely - I hope it can actually be implemented.

Cheers
JJ

Is this with the new design GC front strut? The old design seems to work fine.

Chuck

ard · Apr 7, 2007

Did Jay discuss the new rears? These will have Konis that can be adjusted without the parcel shelf dissassembly. He mentioned a rework of the 60mm threaded collar to maintain the clearance- I am curious as to what you find. I'm going to give it a whirl when the rear Konis arrive.

A

jaj Discussion starter · Apr 7, 2007

Jay and I didn't talk about rears except for a new machined stud that replaces the rear bottom bolt so you can remove the shocks without disturbing the "14mm threads that go into that insanely expensive aluminum rear suspension knuckle", but I wasn't aware of a new damper type as well.

I'll actually be visiting GC on a driving trip to California in about three weeks - I'll know a lot more after that. I'm taking my two adult children to Disneyland, and we're driving 2/3 of the way just so I can drop in on D/A and GC. Am I insane or what?

Cheers
JJ

doug · Apr 7, 2007

JJ-

Please let me know what Jay says. I've been watching these GC threads closely. I'm putting 275's on the front so anything to make that not possible is a deal breaker for me. I understand the old-style Koni's work now, but how long will these be available? Maybe Jay has thoughts on what can be done w/ the new-style dampers? Thanks.

Lscman · Apr 7, 2007

Who predicted this tire clearance issue after hearing the strut tube was shortened?

JJ, could you possibly turn your steering wheel full lock and take a few digital pics of the perch, tire sidewall and Koni tube area?

Hopefully a couple mm of tire clearance can be found without re-engineering this whole setup. If not, here's what I think..

....the front-mounted 9.5" OEM rear wheels on 3mm spacers provide greater benefit than shortened struts (even with their improved jounce & chassis lowering capabilities). The PSS9 & KW crowd may feel otherwise, but I think the ability to inhale the biggie wheels is mission-critical and VERY desireable from a handling perspective. The factory 8" wheels simply cook their tires off under severe duty & no amount of chassis balance tuning can fix that. The skinny 8" wheels simply will not work on a 2 ton noseheavy performance car. Hopefully Jay can find a few mm of clearance to fit these wheels.

Jay Morris may not realize that some folks are already getting some fender lip rub with 9.5" wheels & 3mm spacers & owners of $75K sedans don't take this lightly. This is with a stock suspension setup, or more commonly, a setup that has ~1/4" to 3/8" LESS jounce travel than stock (early GC coilover, K-MAC or Dinan). If jounce travel is increased to a value GREATER than stock, the large wheels with 3mm spacers will probably not work even with max neg camber setting. Clearly, it should be noted that additional jounce can be limited or nicely leveraged thru the use of bigger and softer bumpstops. If added jounce is not "limited", the tires will eat the fenders or vice versa. Added jounce with optional bumpstops for various wheel options would be optimal. IMO, not many folks will accept a front wheel size limitation, as this is what kills KW and PSS9 sales for E39 application.

-----------------------------------------------------------------------------

The optimal setup for E39 M5 and 540i would seem to meet these criteria:

1) Jounce travel equal to stock (approx 3/8" more than early GC). More jounce than OEM creates totally unacceptable fender clearance problems when running 9.5" non-stagger wheel setup.

2) Need a couple mm of tire sidewall clearance in front with 9.5" rear OEM wheels, 275's and 3mm spacers.

----------------------------------------------------

I think jounce travel and tire clearance might be addressed by moving the damper rod and strut mounting hardware upward so it protudes into the engine bay ala Mustang. This trick makes shortened rods unnecessary. It also maintains strut tube height and the threaded perch assembly remains above the tire bulge. This also allows the upper spring perch to be raised, minimizing coil bind. The strut tower center hole is large enough to allow the rod to move off-center for camber adjustment. The strut mounting hardware does not need to reside inside the strut tower as there's plenty of hood clearance. There's fewer strut tower clearance issues than OEM, since the spring diameter is almost halved from stock.

P.S.: My 540i has 9" wheels. Looks like I can run oversize spacer and get by...assuming the added jounce doesn't result in fender contact..:grinyes:

jaj Discussion starter · Apr 7, 2007

Lscman

You've been saying all along that GC is not for the faint of heart, and this thread is all about that!

The point of my posts here is to inform people, but definitely not to complain! I am very happy with GC's customer service, recognizing that it's not as plug and play as other products might be. The fun part is that if you have a question, you can phone the guy that designs the parts and talk to him about it. That's value-added!

Jay is very aware of what's important to the E39 community! The original Koni yellow based version of the front is still available for delivery. My opinion is that with further development, the new system will be better than the yellows. But it's not quite there yet.

The perch clearance to the tire is no different with the new setup than the old. The height of the lower perch is determined by a "stack" made up of the strut-top bearing assembly and the compressed spring. The shorter damper means you can lower the car further but the lower perch will hit the tire at the same ride height it used to hit - the geometry involved is fixed by a triangle defined by the steering knuckle angle, the size of the lower perch, and the size of the tire & wheel assembly. The design of the strut doesn't play a part.

Jay thinks that by putting on a different adjusting sleeve with no lower threads, a stock GC part, there will be clearance for 275's with 3mm spacers. It's a trivial change, and I have the measurements to compare so we can be sure it will work before we go taking things apart. It's an easy fix for me too - ease the strut out from under the fender, take off the bearing, the spring and the lower perch, exchange the threaded sleeve and put it back together. New ones would just be made that way of course. However, if you wanted to slam your car, you'd need the longer threading to be able to get the perch down lower.

It's the second, more aggressive, option that I'm more excited about, frankly. That involves taking advantage of the fact that the new front damper insert is only 46 mm in diameter. If we can mill a flat on the side of the GC alumimum tube and trim away or shorten the adjusting sleeve we can create a larger tire clearance. Milling it far enough to actually expose the 46 mm damper body creates 4 mm more tire clearance than the stock damper. Ergo, 275's would work fine with no wheel spacer at all! For those of us tracking the car, this is a real breakthrough. I'd pay extra for it, in fact.

I'll let you know how my discussions with GC go! Jay's the expert and he may have reasons why this won't work, so for the moment it's just an interesting concept and nothing more.

Cheers
JJ

doug · May 18, 2007

jaj said:
Jay is very aware of what's important to the E39 community! The original Koni yellow based version of the front is still available for delivery. My opinion is that with further development, the new system will be better than the yellows. But it's not quite there yet.

Jay thinks that by putting on a different adjusting sleeve with no lower threads, a stock GC part, there will be clearance for 275's with 3mm spacers. It's a trivial change, and I have the measurements to compare so we can be sure it will work before we go taking things apart. It's an easy fix for me too - ease the strut out from under the fender, take off the bearing, the spring and the lower perch, exchange the threaded sleeve and put it back together. New ones would just be made that way of course. However, if you wanted to slam your car, you'd need the longer threading to be able to get the perch down lower.

I'll let you know how my discussions with GC go! Jay's the expert and he may have reasons why this won't work, so for the moment it's just an interesting concept and nothing more.

Cheers
JJ

JJ- I just wanted to follow up on this most informative thread to see if you ever got back to see Jay, and what he had to say. Thanks a lot.

jaj Discussion starter · Apr 7, 2007

Photo, as requested. This is with 8" front rim and 245 tire. Ride height is 14-1/8". Front end was off the ground so the suspension is at full droop in this shot.

Cheers
JJ

CSBM5 · Apr 8, 2007

Good work JJ! It's great to see that someone like yourself is taking the lead on this and working with Jay for a solution.

From looking at your pic, it appears that you are almost at the maximum ride height available with your current spring? This link show the yellow GC setup with stock wheel/tire, but it is taken from a much different angle. This again is Redshift's car, and since he was one of the first GC installs, he has something like 370 lb/in or 350 lb/in springs up front. At the setting shown, his ride height was around 12.5", so it was raised significantly. However, it at least shows some comparison to your pic.

As far as milling the strut tube goes -- don't do it. That tube is under continuous cyclic loading in compression, and you do not want to introduce a stress concentration to one region like that.

Chuck

jaj Discussion starter · Apr 8, 2007

Chuck

I probably didn't explain it very clearly - the heart of the strut assembly is a Koni single-tube damper that sits inside an 50 mm diameter aluminum tube. The tube and the damper both contribute to the structural integrity of the unit, and the damper could probably do the job on its own. In the photo, the red cylinder visible between the top of the knuckle and the bottom of the adjusting sleeve is the 50 mm aluminum tube, not the damper. And, just to be clear, I wasn't planning on milling anything myself - it would have to come from GC that way - Jay's the expert and if he's ok with it, so am I. To be clear, he hasn't said one way or the other - it's a work-in-progress.

As for the flat itself, it's only 1 mm or so deep. It's a trim, not major surgery.

In fact, it may not be necessary to mill it at all. If we can get the adjusting sleeve out of the way, the unmilled 50mm tube provides just enough clearance to run 275's on stock 9.5" rims without 3 mm wheel spacers. You get the same clearance as you get with Koni FSD's with the 3mm spacer. I know this because I have a set of FSD's, and while you do get a small black mark on the shock tube there are no visible marks on the tire.

The second part of the mod is shortening the adjusting sleeve and moving its support ring up so that a 275 tire doesn't run into it. This approach limits the available adjustment range, but as Lscman has pointed out before, your ride height for the track should be around 14" or more, and for daily driving that's a good height as well. Those limits don't change if you remove the part of the sleeve you can't use anyway. The photo doesn't correctly show the geometry - I angled the camera to show how it's all put together, but the tire looks higher than it actually is. I'm guessing that I can probably lower the car about 1" (to 13") before there's a problem with 275's.

As for ride height, yes, I've adjusted it as high as it will go to get 14-1/8" with 430# 7" springs. When I had the alignment checked by the dealer after the install, the ride height with a full load of sandbags and lead shot was within 5 mm of stock both front and rear. We set it to 2 degrees negative camber in the rear and 1 degree (for the street) in the front. Front and rear toe is right on the factory settings. I'll push the front camber to 2 degrees for the track.

Cheers
JJ

Lscman · Apr 8, 2007

I did not realize that Jay was employing his new GC red composite Koni solution. This must be similar to the clever technology he used for the '05 and up Mustang. Some of Koni's default metal hardware has been removed from the tubing top to restore jounce. This is good.

It seems the lower perch can indeed be jacked well above the tire sidewall bulge, so the new shock body is not too short.

Looks like details might be worked out, if the body of the shock can be reduced or relieved a bit, to create a couple mm of clearance for 275's.

jaj Discussion starter · Apr 8, 2007

More pix, more measurements

After another couple of hours of rolling around on my creeper and measuring things, here's what I know.

1. If you just put a 275 Michelin PS1 on the front with no spacer, the tire "just" touches the threaded adjustment tube. The only part of the sidewall that touches is the anti-curbing strip although the very bottom of the lettering might get there as well. You can turn it easily - the drag is no greater than just the brake rotors in the calipers.

2. A "forensic" look at the KONI FSD tire mark (see picture below) suggests that a 46mm diameter shock tube would remain unmarked. The mark was on the FSD after a track day with speeds to 130 MPH with 275's and 3 mm spacers, so the sideloads were about as high as they can get.

So what does it all mean? Picture 1 has the whole story:

The upper felt-pen mark indicates where the bottom of the adjusting sleeve has to be to maintain a minimum clearance of 7 mm between the tire and the strut. The lower marking (black band) shows where the "flat" needs to be cut. The flat should be about 0.6" high and about 1.5 mm deep and that will give you about 6.5 mm clearance from the tire to the strut. The tire will touch occasionally, but only lightly.

The second picture shows the FSD with a tire mark on it. I compared the location of the mark with the installed components, and the "flat" that I propose is in the right place to create space to prevent the marking. The mark is 20mm wide, suggesting that the tire sidewall was deflected by 1.8 mm.

The last picture is just for fun. What's the difference between an FSD and a stock Boge? The damper bodies are the same length, but the stock rod is THREE INCHES shorter than the Koni rod! No wonder the stock ones are a breeze to get out from under the fender! Who'da thought?

Cheers
JJ

CSBM5 · Apr 8, 2007

Excellent work JJ. I'm sure Jay can use this information -- you've probably already pointed him to this thread.

Good job!

Chuck

jaj Discussion starter · May 19, 2007

Jay's the expert on this stuff and has implemented the design changes. I haven't posted on them because I haven't installed them yet. I'm hoping to be in one place long enough next weekend (Mem day weekend) to put them in and take a few happy snaps for all of us.

I have trial fit some prototype parts already though, and it looks like 275's with no spacer will work.

Cheers
JJ

Lscman · May 19, 2007

Anxious to see/hear details.:thumbsup: :cheers: :blabla: :applause:

GC New Technology Fronts and three Install DIY's

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