nuts105

An older thread was just closed by some admin..and I think other should be able to chime in as there isn't a single thread on this subject with enough info.

I just installed the upgrade kit # 12499507 on my '98 A4 vert with 15 year old F45 system. I bought the kit somewhere else with ok experience, but others have pointed to Fichtner's having good prices.

The instructions are clear enough, but there are pitfalls:

I snapped the 24mm bolt trying to torque it to the ridiculous 162 ft/lb per manual, and had to order an overnight replacement at $40 shipping cost. If I had had any experience at these high torques, it would have been obvious this is nuts. And a query for this comes up quickly with a service bulletin about snapped bolts and that the right torque is 107 ft/lb. I'm guessing no one tightens those rear shock bolts to the 162 because it's a herculean effort, and then they don't mention it - I could feel the second shock bolt was about to snap at 140, so it seems universal.
The shocks have to be compressed all (!) the way down with zip ties for enough wiggle room to properly position them. You need to double loop them otherwise they will (!) break. When they do break, the shock expands explosively. It would have been very scary (to me) if the ties snapped in there while the shocks were not aligned yet. Because it might be pretty impossible to compress them again from there or remove them. The next really scary thing was that the connector on top of the rear shocks, being very fragile and all, is the same size as the hole through which you have to move it while plugged on top of the shock. If those damn zips snap while you're forcing it in position, you can forget about that connector. Careful!

I spent a lot of time installing each shock. Like 2-3 hours each. Each bolt has little room for a wrench + extensions, building a net of zip ties and compression, wiggling the shock into position, adjusting the secondary jack, removing the connectors all the way back there, all takes time. I feel people are about as honest with their times as with the size of the fish they catch, unless you're somebody that works on a lot of cars all the time.
The new computer installs upside down compared to the old one and has an attachment about double the size, and that part sticks out too much to put that trunk compartment lid back on. Nothing that important, but weird I don't see it mentioned anywhere.
So why do this nail biting work and spend two grand?

Because...I love love love the new ride! It's like sinking into a sofa on my commute on the tour setting. If you use the c5 as a DD, and still have the F45, you are so missing out if you don't take the opportunity to upgrade to the F55. Compared to a classic Cadillac boat ride (say '79 CDV..), it has the fantastic slow motion bounciness that keeps you level at all times, yet you still feel all the road imperfections as an informational undercurrent. And of course when you don't go in a straight line, it tightens up even in tour to keep a good grip.
It's just such an awesome ride. Let's call it precise comfort. Of course the sport mode should be comparable to the fixed suspensions, but even there you feel a smoothness and preciseness that I don't recall from a non-adjustable.
While this is nothing new for C6 drivers with F55 I suppose, I feel I have the best car with the best tech on the planet with ample torque for fun: I replaced all the wearable parts, but didn't do any bolt ons other than the sway C06Z6 sway bars.
If this ever was not enough, I'd add a supercharger. For now I truly don't feel the need.

Bill Curlee

Im glad that you were able to accomplish this up-grade. I remember a post on this topic and procedure a while back but i didnt save it.

I had F-45 on my 98 Coupe and I HATED IT.
Once I drove the ZO6, the adjustable shocks made me hate the 98 even more. If I would have kept the car, I would have deleted the F-45 option and installed C5 ZO6 springs and sways C6 ZO6 shocks

I have not driven a car with F-55 so I have no opinion on that set up.

Good Job on the swap and excellent write up.

Bill

vettegroves

Thanks nuts105 for posting this again. But still not much talk on this. I've been seriously considering for a while the f45 to f55 conversion. Seems most that have f55 (already was on car) don't like it, but others that installed it like it....
u still love love love it?
is the kit still available? how much and where?

Smoken1

I will say that the C6 shocks and Z51 bars are the way to go with 4-10ohm resistors.
One at each corner so you get no codes forget that adjustable crap

Plasticman

I changed from F55 to Bilstein Sport shocks, and have not notice any difference (F55 shocks were leaking badly at 30K miles).

Note that I always kept my F55 in the "Sport" setting. "Tour" setting was way too soft for me.

Best price I found last year was over $600 per F55 shock - uninstalled. I got the 4 Bilsteins for $360 (plus $75 for a tuner to program out the F55), it did not make sense to keep the F55 system.

I will never purchase another vehicle with that system.. highly over rated.

Plasticman

nuts105

The yahoo mail idiots probably move CF to spam so I never see if anyone replies.
Yes I still love the suspension. I can take dips at 30mph in sport like I was on rails, that would completely unsettle my new daily driver car at 20mph. Sport is very tight. Touring is comfy - only problem is it can bottom out on curbs, but still less than the old one. I don't know if they wear out fast, but a few anecdotal cases don't scare me. All I know is that they are a factor of 10 better than the F45 ever was. I really never had been impressed with anyone's car's suspension before, with the F55 I know you can be.

Patches

Here's my "relocated" F45.



I swapped in LG GT2 CO's recently - fully adjustable. Can't wait to get it back out on the road.

jackthelad

The thing I love about F45 (still working, BTW) is the comfortable highway ride - and these days, most of my mileage is, sadly, highway vs. backroads. Until one of them starts leaking, I am not ready to give that up.

mikeam

Me too! But opposite of you, I'm backroads and Performance mode!

KGoodwin

Here is what I saved from 2010: Purchased a conversion kit GM # 12499507 from Fichtner Chevrolet. Fichtner ships direct from GM which took 3 days. I went with the F55 upgrade since the incremental cost over replacing the F45 shocks seemed worth the cost. The upgrade kit is complete for the F45 optioned C5, the supplied instructions are excellent although a little on the generic side. Here are my main suggestions:
1. The rear shocks are RH and LH specific and the Jumper harnesses (from the F55 shock tower to the existing pigtail attached on the frame) are front and rear specific. Mark them as soon as you open the box.
2. The F45 shocks are not under tension (can easily be compressed by hand) so they remove without a problem.
3. Not so with F55 shocks which are under tension. I found McRat’s zip tie method to work as advertised (your normal Republican bondage scene). There are some good shock replacement DIY procedures that supplement the shop manual. McRat’s are at http://fuzzydiceracing.com/test.htm in addition to http://www.c5forum.com/diy/shocks.php McRat complained about having to double up on the zip ties because he thought his were cheap. Even the expensive ones break so doubling up on the zip ties is mandatory in my estimation.
4. Compress the F55 shocks as far as they will go. Make sure you have the zip ties aligned so you don’t have to rotate the upper and lower sections of the shocks when installing them in the frame towers as this will likely break the zip ties. The shocks will take two seconds to expand (they don’t explode open) but you don’t want to chance it. Have everything properly lined up when you cut the zip ties. I had the upper bolts started and the lower portion of the shocks as close to the mounts as I could place them although the lower portion of the F55 shocks can be manipulated into position without a major effort after cutting the cable/zip ties.
5. The only panic attack I had was connecting the 90-degree electrical connector to the top of the F55 front shocks. It appeared that there was no way of getting the connector pushed onto the top of the shock from the underside of the car. It can be easily done from the wheel well if you approach the shock connection from the center line of the car; that is, bringing the 90-degree connector in from the back side and not in from the front where there isn’t enough room between the plastic cowling and the shock post. I preferred to remove/push back the window washer reservoir on the driver’s side/the coolant resoiviour on the passenger side to gain full access to the top of the shock. (No need to drain anything.) Pushing the connector onto the shock takes a little effort and at these prices, you want to be aligned properly.
6. My F55 shocks measured 1.1 to 1.2 ohms when testing the installed connector as per the F55 instructions.
7. I couldn’t get my torque wrench using a crow-foot onto the front shock’s upper mounting bolt but since it is only required 26 Nm, I used my calibrated muscles.
8. Replacing the F45 controller with the F55 controller was trivial. I didn’t even know a computer was located in the rear interior storage tub. The two electrical connectors are keyed (no way you can install them incorrectly) but in comparing the relative position of the F45 connections to the F55 ones, the connector that was on top is now of the bottom and vice versa.
9. The wiring pigtail for the original shock is attached to the frame and is used with the new and exactly the same F55 connector on the supplied harness. Take some effort in using a small screwdriver to remove the old connector since the little 10 cent plastic holdown attached to the frame (GM 12186353) costs $6 at your local GM dealer and in Houston had to be special ordered from Michigan (I found zip ties where a dealer repair must have broken the pigtail holdown. The ties obviously did the job but it wasn’t how GM had manufactured the car.)
10. Again the supplied instructions are very clear. It took me about an hour per wheel (I take my time and clean everything including the electrical connections) plus another hour to jack up and remove the wheels - so in all a good day of being a shade tree mechanic (even without McRat’s Corona supplement).