Hi there? Does any one here knows any difference between the FHP springs for 550M/575M parts#175886 front & 175887 rear vs #208678 front & 208679 rear? Thanks Alex
$100 says terry knows my guess is that there is a factory spring and the other is the cosmo spring. never really sure if they both have the same spring rates.
Non-technical answer : on the UK parts site the latter are listed as GTC rather than FHP - this is also shown on the FNA TSB 1265A
Jimmie Gets a cigar. The HGTC springs (208678/9) are made by Cosmos and the FHP springs (175886/7) are made by Cagnola for the factory. The FHP springs are over twice the cost of the HGTC springs, for some reason. Compared to the stock 575M springs (16348/9 and 169985/6, similar spring types, one carried over from the 550) the FHP springs are made of heavier wire (15 mm vs 14.3/14.5 mm F and 12.5 mm vs 12.2/12.5 mm R), are shorter (238 mm vs ~275 mm F and 259 mm vs ~283 mm R uncompressed) and have 10-13mm shorter compressed length, and about the same dynamic loads on all three, F & R. This provides a stiffer ride, less roll, and less pitch than the standard springs. In my opinion, the HGTC springs are a compromise in between standard and FHP springs, softer than the FHP and stiffer than the standard springs. This is consistent with the smaller than FHP HGTC rear anti-roll bar with standard 17 mm, FHP 21 mm, and HGTC 19.5 mm bars. Now all we need is a 575 HGTC owner to take a micrometer and measure the diameter of his car's F & R spring wire and, just to make sure, his rear anti-roll bar, and we will know for sure. I have seen no specs on the HGTC springs or shock absorbers. Only the tech bulletin posted in multiple threads here. Later, I will make a table of spring characteristics and post it in the 575 Assembly/Serial Number thread. Taz Terry Phillips
Thank you Terry, Very detail information. I have my 575 came standard new car FHP option with the Cagnola springs (175886/7) worked really good for regular road driving, but significantly soft when agressive driving on the track. After upgraded the GTC suspension ECU for the 575M, the new ECU parameter setting seems to control the shocks and springs a lot better for track agressive driving while still brings comfort for regular road driving. Now, for my 550 which came standard with (169985/6) in which I am installing the Moton Club Sport shocks with factory springs as the Moton people recommended. I can feel that the (169985/6) springs are not firm enough and sporty enough to work with the Moton shocks, so I need to order the (175886/7) or (208678/9) for to work with Moton shocks. It looks like I will go with the (175886/7) springs. Thanks again.... Alex
Alex- It would be a big help to us if you could give us either your 575M's Serial Number (last 6 numbers in VIN) or Assembly Number (under the hood/bonnet forward of the large black metal panel, no. 5 below) so we can see whether the HGTC ECU will fit our cars. We know the HGTC ECU will fit all 575Ms after Assembly Number 52556 (SN ~1353XX), but are not sure it will fit earlier cars. I would buy one if it fit and so would several other owners. Taz Terry Phillips Image Unavailable, Please Login
Hello Terry, My 575M Vin is 131726, Jan. 2003. My friend who has a 2005 575M GTC car had a problem with his suspension warning light often came on in which he purchased another GTC suspension ECU, and yet problem not solved, later his problem was found due to a small wire with poor connection. So wire fixed, problem fixed, than he gave me this extra GTC ECU to me in which I install onto my 131726 575M. It works as you can immidiately tell while driving it, but the problem is the suspension warning light will lit, and we can not turn it off. So I live with it for already two years, still enjoy the sensational driving feel the GTC ECU offers. Thanks and hope this will help you. Alex
Alex- That is what I was afraid would happen. At ~Serial Number 1353XX (Assembly No 52556), a steering position sensor was introduced and the wiring harnesses and shock/suspension ECU and Motronic ECU were changed to provide the steering sensor data to the shock absorbers to speed up shock absorber reaction time. The 456/456M had a steering sensor throughout production, but the 550 and early 575Ms (through ~ Nov/Dec 2003, early MY 2004) did not. The HGTC ECU you have installed is looking for that steering position data from your Motronic ECU. Since it is not there, the ECU gives you a suspension warning lamp. On a car built after the steering sensor was installed, a code would be set indicating a steering position sensor error that could be read with an SD2/3 if there was a sensor failure. Your Motronic ECU, however, does not even have that code programmed into it, so you just get the suspension lamp with no way to diagnose the problem. Taz Terry Phillips
Hello Terry, Thanks again, I think you are right about the suspension warning light on. Let me know if you have any suggestion and or solutions for it? Or should I just continue driving it the way it is now? Thanks Alex
Alex- It will not hurt anything, but will mask any real suspension warnings you get. None of those pose any danger to the car, however, so it is not a big deal. Every time you have your car serviced, you can ask your technicians to use the SD2/3 and see if there are any real suspension codes set in there. Likely there will not be any. If the light does not bother you, keep on trucking. You may have the same problem with your Moton shocks on your 550, unless they have an ECU fix. Incidentally, the FHP steering ECU will fit your 550 and will improve the steering feel and response. Taz Terry Phillips
Thanks again, we have tried to block the suspension warning light and TPMS using SD2, no luck there. Will live with it the way it is now. Alex
how does the novitec / kv (?) suspension block the light ? i wonder if there is a way to trick it into thinking it is getting a signal...
The previous owner of my 575M replaced the springs with the 208678/9 combination which is the HGTC versions. Diameters of the spring wire are 15mm F and 13mm R. He didn't replace the rear sway bar which is a 17mm standard.
Cambo- Thanks for the information. It appears the FHP and HGTC springs are virtually identical for the front, then, and the HGTC rear springs are actually stiffer (13 mm wire vs 12.5 mm wire). So my guess was incorrect. That could explain why the rear anti-roll bar was decreased in diameter as they fine tuned the suspension. The HGTC rear anti-roll bar is 210888 and the bushings (2) are 210897. Taz Terry Phillips
