F45 to F55 Suspension Conversion
04-12-2010, 01:23 AM
#1
Instructor
Thread Starter
F45 to F55 Suspension Conversion
I followed TAGDENNIS’s lead and purchased a conversion kit GM # 12499507 from Fichtner Chevrolet (Bob Wendorff – Parts Mgr @ 800-234-5284) since their price with shipping was $204 less than obtainable on the Internet. 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).
Contact me if you have any questions, I can send you a pdf copy of the GM instructions if interested. It isn’t a cheap upgrade but neither was the original F45 option on the C5.
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).
Contact me if you have any questions, I can send you a pdf copy of the GM instructions if interested. It isn’t a cheap upgrade but neither was the original F45 option on the C5.
04-12-2010, 09:23 AM
#2
Drifting
Member Since: Feb 2002
Location: Park Ridge Illinois
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Congrats, you'll love the difference! I did my conversion without the kit and used parts from a wrecked 03 anniversary car.
11-04-2012, 02:57 AM
#3
upgrade kit same parts as standard F55?
Can someone please confirm what Jason says works? Are the F55 standard parts exactly the same as the ones in the F45 to F55 upgrade kit, most importantly, is the controller the same?
11-04-2012, 11:59 AM
#6
11-04-2012, 07:03 PM
#8
Melting Slicks
I will say that hardly anyone seems to post/talk about this particular conversion on a frequent basis.
I went with the Hotchkis Sport Sways and kept the F45 system for now since I only have 25k miles and no real shock/handling issues.
But, sooner or later I will have to decide on sport shocks, coilovers, F45 shocks or F55 conversion.
So, any input along the line of deciding on those options would be of interest to me and probably some others.
Since I'm mostly performance street driving/canyon carving with a little autocrossing thrown in, the answers are not really as clear cut from a cost/benefit perspective as they would be if I was often tracking and or doing frequent serious autocrossing.
I'm hazarding that the most expensive option is F55 conversion ($4500-5000?), followed by lite coilovers ($5,000-1900?), followed by C6 ZO6/shocks & springs or maybe by Bilstein Sports & Z51 springs ($800-600?) if street ride is important. But, I'm only guessing. So perhaps there are more than a few of us that would benefit from thoughts/comparisons along these lines.
Anyone with an F55 system that switched to coilovers and who is either happy or now regrets the change? Thanks. Also, would love to hear from F45 to F55 converters who can detail the real world benefits. Not meaning to thread jack. Sorry if I am.
I went with the Hotchkis Sport Sways and kept the F45 system for now since I only have 25k miles and no real shock/handling issues.
But, sooner or later I will have to decide on sport shocks, coilovers, F45 shocks or F55 conversion.
So, any input along the line of deciding on those options would be of interest to me and probably some others.
Since I'm mostly performance street driving/canyon carving with a little autocrossing thrown in, the answers are not really as clear cut from a cost/benefit perspective as they would be if I was often tracking and or doing frequent serious autocrossing.
I'm hazarding that the most expensive option is F55 conversion ($4500-5000?), followed by lite coilovers ($5,000-1900?), followed by C6 ZO6/shocks & springs or maybe by Bilstein Sports & Z51 springs ($800-600?) if street ride is important. But, I'm only guessing. So perhaps there are more than a few of us that would benefit from thoughts/comparisons along these lines.
Anyone with an F55 system that switched to coilovers and who is either happy or now regrets the change? Thanks. Also, would love to hear from F45 to F55 converters who can detail the real world benefits. Not meaning to thread jack. Sorry if I am.
Last edited by B747VET; 11-04-2012 at 07:29 PM.
03-19-2013, 01:11 AM
#10
got it
I finally bit the bullet and bought the upgrade kit 12499507. The original F45 shocks in my 98 are making wheezing noises over any kind of rough road now, even though they still work nicely I would say, they make the car sound like something from the junkjard. After 15 years, time to replace the shocks, right?
At $2100 or so and no sales tax it's not such a terrible deal and looks even cheaper than replacing the magnerides on newer corvettes. I decided I wouldn't be able to drive the car as my DD without the comfort of the adjustables, at least not on the 3rd world streets of LA, and it seems I will be getting an awesome upgrade with the magnerides at the same time.
Will update with the experience once I find a free weekend and an empty garage to swap them in.
At $2100 or so and no sales tax it's not such a terrible deal and looks even cheaper than replacing the magnerides on newer corvettes. I decided I wouldn't be able to drive the car as my DD without the comfort of the adjustables, at least not on the 3rd world streets of LA, and it seems I will be getting an awesome upgrade with the magnerides at the same time.
Will update with the experience once I find a free weekend and an empty garage to swap them in.
04-04-2013, 03:07 AM
#11
Done
Finished installing. My first impression is it's pretty darn great. Drives like a Cadillac in tour and very tight yet smooth in sport. Like a Ferrari?
Now here some advice. I'm pretty disappointed with the instructions above, in particular because I snapped the 24mm bolt trying to torque it to the ridiculous 162 ft/lb, 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 it should only be tightened at 107 ft/lb. I think no one tightens it to the 162 because it's a herculean effort and then they don't mention it - I could feel the second bolt about to snap at 140, so it seems universal.
Enough about the bolt. The next thing that I noticed was that the shocks don't take 2 seconds to expand as claimed above, but rather explode out (as they should I figure). They are a b*tch to compress ALL the way down which is needed to wiggle them in. 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. And yes those zip ties did break when I only used single loops. 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 MUCH longer installing each shock. More like 2-3 hours each. Each bolt has little room for a wrench + extensions, 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 how big the fish is they catch, unless you're somebody that works on a lot of cars all the time.
What's weird is I didn't hear mentioned either that the new computer installs upside down compared to the old one, and one part sticks out too much to put that trunk compartment top back on. Nothing that important, but weird no one mentions it.
A lot of nail biting work and money, but worth it.
Now here some advice. I'm pretty disappointed with the instructions above, in particular because I snapped the 24mm bolt trying to torque it to the ridiculous 162 ft/lb, 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 it should only be tightened at 107 ft/lb. I think no one tightens it to the 162 because it's a herculean effort and then they don't mention it - I could feel the second bolt about to snap at 140, so it seems universal.
Enough about the bolt. The next thing that I noticed was that the shocks don't take 2 seconds to expand as claimed above, but rather explode out (as they should I figure). They are a b*tch to compress ALL the way down which is needed to wiggle them in. 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. And yes those zip ties did break when I only used single loops. 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 MUCH longer installing each shock. More like 2-3 hours each. Each bolt has little room for a wrench + extensions, 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 how big the fish is they catch, unless you're somebody that works on a lot of cars all the time.
What's weird is I didn't hear mentioned either that the new computer installs upside down compared to the old one, and one part sticks out too much to put that trunk compartment top back on. Nothing that important, but weird no one mentions it.
A lot of nail biting work and money, but worth it.
Last edited by nuts105; 04-04-2013 at 03:27 AM.
04-04-2013, 03:21 AM
#12
I'm guessing they may run out of the kits soon. A lot of places sell them at list price now. The computer seems special to the upgrade kit as I couldn't even find the part number listed. Even the shocks might be custom but maybe not. I doubt they still make the kit.
