august Posted December 17, 2006 Report Share Posted December 17, 2006 does anyone know if the 604 springs are compatible with the 505? And if so, does anyone know the spring rates? ...still in search of a cheap spring upgrade solution. Quote Link to comment Share on other sites More sharing options...
Bean Posted December 18, 2006 Report Share Posted December 18, 2006 Hey August - 604 springs should be heavier - but if you use them I'd guess the car will sit quite high. Spring rate will be higher - but the ride height is calculated into the spring - so a lighter car is going to sit higher. I noticed the 505's I've stripped sit noticibly higher with just the interior gutted... I think we're going on our own to try one of the known combos to see if it works for our driving style - something like VM's volvo front and MB rear maybe... Rabin Quote Link to comment Share on other sites More sharing options...
Metako Posted December 18, 2006 Report Share Posted December 18, 2006 the 14mm 604 spring may have potential depending on your current wire thickness: http://www.aussiefrogs.com/forum/showthread.php?t=39971 15% stiffer than 13.5mm GTi/turbo, and if we cut coils and leave 5 coils instead of 5.3 we may get the desired lowered ride height. I didnt think you could just heat and bend springs but Thanos seems to have success with it. Wish I could find the other 604 spring so I could try them on the car! What is your current wire thickness? here's a pic of the 604 spring with 5.5 coils left. Will cut it again so only 5 coils left (and look again for the other spring). Quote Link to comment Share on other sites More sharing options...
august Posted December 19, 2006 Author Report Share Posted December 19, 2006 the 14mm 604 spring may have potential depending on your current wire thickness: http://www.aussiefrogs.com/forum/showthread.php?t=39971 15% stiffer than 13.5mm GTi/turbo, and if we cut coils and leave 5 coils instead of 5.3 we may get the desired lowered ride height. I didnt think you could just heat and bend springs but Thanos seems to have success with it. Wish I could find the other 604 spring so I could try them on the car! What is your current wire thickness? here's a pic of the 604 spring with 5.5 coils left. Will cut it again so only 5 coils left (and look again for the other spring). thanks Metako. have you or anyone else compared the complete set of 505 -> 604 springs (front and rear?), like are they the same ratio as far as thickness / spring rate front to rear as the 505? in the future i would really like to find something that's an even increase (F+R) in rate to try to keep the balance somewhat in check. what about jumping back to stock springs for a second: cutting one coil off the front turbo springs lowers the front end a perfect amount IMO (still need you get you better pictures Metako), but cutting one coil from the rear lowers the car a lot more then the 1 coil off the front (i recently learned this the hard way). so I'm trying to figure out how to keep it in 'balance' when cutting the rear springs. I'm guessing 1/2 -> 3/4 would be right, but i'm really not sure. argh aussiefrogs has some great spring info for sure. where is that spring database they are all talking about though, i can't seem to find it!?! Quote Link to comment Share on other sites More sharing options...
Metako Posted December 19, 2006 Report Share Posted December 19, 2006 here's the link to the database. Hasnt really got much info though. http://www.aussiefrogs.com/forum/showthread.php?t=27966 there is a 604 register on Aussiefrogs (link below), maybe you could ask there, but is the front/rear weight balance the same on the 604 as the 505? I guess you could work out the spring rates of your proposed new springs and make sure the f/r balance is similar to the origional. Once you have found/made rear springs with the correct rate to balance with the fronts, and if the height was not correct, you could always get a spring maker to "re-set" the spring to the desired height ie compress it or stretch it, without changing it's rate. http://www.aussiefrogs.com/forum/showthread.php?t=18218 Quote Link to comment Share on other sites More sharing options...
Bean Posted December 20, 2006 Report Share Posted December 20, 2006 There are some spring calculation equations - like the ones Metako used - that should allow you to calculate the spring rate of the springs of the front. Knowing the rate and the length of the spring means you can then calculate the spring rate after some has been cut. Should be able to calcualte the increase with one coil cut - then do similar calcs on the rear spring to find how much to cut to get a similar increase. Should also be able to calculate the ride height change... I have text book from school and an entire section was spring design - just need to dig it up when I get back home. Rabin Quote Link to comment Share on other sites More sharing options...
Johnny Posted December 20, 2006 Report Share Posted December 20, 2006 Is that book of yours discussing car-springs design or general spring-design? I know that springs are springs, no matter the application they are used in, but I don't know what one wants to achieve when changeing springs and struts. I know the formulas and how to use them for calculating such things like hight, spring rates and such. I just don't know what to use them for . It would be great if someone could explain the basics. If anyone's interested, I could make a little excel-sheet that could calculate what you want. The only problem is that my formulas uses SI-units (N,m etc..). Quote Link to comment Share on other sites More sharing options...
Metako Posted December 23, 2006 Report Share Posted December 23, 2006 that would be great Johnny! Maybe include a conversion table for lb/sq inch to NM, and inches to mm etc. Quote Link to comment Share on other sites More sharing options...
Bean Posted December 24, 2006 Report Share Posted December 24, 2006 Text book is just general spring design - but like you said a spring is a spring. Should be able to get close results since we can determine the length and number of coils manually, plus there's documentation of the spring rates - so with all that info we should be able to reverse engineer a spring calc that we can then use to spec out springs. All in theory now- but I can't see how it won't work. I'm currently in Charlottesville VA visiting my bro and his family for Christmas though - won't be back till the new year. Rabin Quote Link to comment Share on other sites More sharing options...
Johnny Posted December 29, 2006 Report Share Posted December 29, 2006 Hehe, I have made the spreadsheet now but I can't upload the it because I'm not permitted to upload a file with that file extension. =/ Maybe admin could fix this? the extension is .xls Quote Link to comment Share on other sites More sharing options...
august Posted December 29, 2006 Author Report Share Posted December 29, 2006 Rabin, sounds really good, let us know when you get back... Johnny, try zipping the archive, or using rar or 7zip so the extention is different. if worse comes to worse i'd imagine you could upload with no extension, or a .xls_ extension, and just tell people to rename I talked to a local Peugeot mechanic about this and he's confirmed that he's installed 604 rear springs in the rear of a 505. He didn't cut them though, and as you can imagine, the rear ride height is quite high Also, while at the yards up north a few days ago, we were scoping out a volvo 240. The front springs look identical visually, so I'm really looking foward to checking that out. (props V-M!) Quote Link to comment Share on other sites More sharing options...
Johnny Posted December 29, 2006 Report Share Posted December 29, 2006 I renamed it to .txt instead. just rename it to Springrates.xls and it should work. See it as a first edition Springrates.txt Quote Link to comment Share on other sites More sharing options...
august Posted December 30, 2006 Author Report Share Posted December 30, 2006 I renamed it to .txt instead. just rename it to Springrates.xls and it should work. See it as a first edition nice one johnny! I've uploaded it here as well: http://www.505turbo.com/august/technical/Springrates.xls Quote Link to comment Share on other sites More sharing options...
Johnny Posted December 31, 2006 Report Share Posted December 31, 2006 I think that it needs too be checked by someone else before really thrusting it. The default spring-data should be accurate for standard springs (D in front, A in rear). Everything matches the spring-data from to sheets except one thing: On the D-type it is stated that when a force of 3550N is acting on the spring, the springs length is 232mm. IE, it has been compressed 498-232 = 266mm. But when you test this in my sheet then the spring is compressed 232mm. Altough the spring-rate matches. Another strange thing is that the stress is way too high for the front spring.... Something is wrong but I just can't see what. Quote Link to comment Share on other sites More sharing options...
Metako Posted December 31, 2006 Report Share Posted December 31, 2006 well done Johnny. Someone has offered me a 604 spring but I'll have to wait a couple of weeks till he comes to my state with it. Good to hear about the 604 rears working on the 505 August. Any idea what wire thickness the 604 rears have? Happy New Year to all on the forum! Quote Link to comment Share on other sites More sharing options...
Metako Posted January 3, 2007 Report Share Posted January 3, 2007 Johnny, been playing with the table and wondering what "spring decompression" is. What measurement does this relate to? Also do the std turbo springs have 8 free coils, and the rears 10? Are all the other calculations dependent on these base values being correct? It seems to work great apart from these questions. Quote Link to comment Share on other sites More sharing options...
august Posted January 4, 2007 Author Report Share Posted January 4, 2007 hmm, i just heard from victor that he saw a set of billstein coil overs on a 505 at the track once. he was thinking there was a peugeot part number for them, but this seems idea. if we could get something that's already been tuned for a 505 (!!!). we need to do some research on this one for sure Quote Link to comment Share on other sites More sharing options...
Metako Posted January 4, 2007 Report Share Posted January 4, 2007 more good info from Thanos: somewhere else he states that the factory believes the best Front to Rear ratio with 505 springs is 1:3 (eg 100lb" and 300lb"), whereas he has found a ratio of 1:2.5 is better (eg 120lb" and 300lb") for handling as log as you increase front camber to at least 2.5 degrees, which would probably occur if you lowered a 505. Works_coupe_suspension_2.doc Works_coupe_suspension_3.doc Quote Link to comment Share on other sites More sharing options...
Johnny Posted January 5, 2007 Report Share Posted January 5, 2007 Johnny, been playing with the table and wondering what "spring decompression" is. What measurement does this relate to? Also do the std turbo springs have 8 free coils, and the rears 10? Are all the other calculations dependent on these base values being correct? It seems to work great apart from these questions. Ooops, "decompression" was a bad choice of word, compression would have been better. Spring (de)compression is simply how much the spring compresses with a force (P) acting on it. This relates to the weight of the car and the spring rate. Actully, the std turbosprings (if the std turbospring is the A-spring) has 8.75 coils. I don't know how many coils the rear spring has. There's another thing though: The table subtracts a value from the total coils to determine the "active" coils. I have this value fixed to 1.5, but this is not accurate. Actully, this value could change depending on how the spring looks. I have made a new version of the table so that you can choose this value instead (I call it n*), and I've also included a little table to help you choose this value. And there's another thing, the G-modulus (modulus of rigidity) seem to be different depending on what spring we're talking about. How I know this? I have made another spreadsheet that calculates G-modulus and then I altered the n* parameter to see which n*-value gave a resonable G-modulus (It should be around 80kN/mm2). The G-modulus seem to be either 79 or 81, depending on the particular spring. (the other values I got was way off) Also, and the n*value seem o be either 1 or 2. In the updated version I've included a table for the standard springs (A-G, I think) that includes coils, G-modulus and n*, although it is incomplete. I got some data on 505 front springs from Toni's site and then compared it to the document found here under resources and found 4 matching springs, the data from Toni's site had info on the coils of the springs. Link to the document on Toni's site: http://www.peugeot505.info/files/sb/sb_1984_xx_my84_n05.pdf I've also changed the formula for the rideheight, it assumed that the distance between the coils are the same the whole way of the spring. Because I've realised that this is not true, I changed the spreadsheet so that you enter the height of the spring before cutting and after. I belive this would yield a more accurate result. The new version also calculates the frequency of the spring for those interested. This requires that you weigh the spring. I will post this update tomorrow. more good info from Thanos: Do you know if he got that info from counting coils on an actual spring or if that data is from factory sheets? Quote Link to comment Share on other sites More sharing options...
august Posted January 5, 2007 Author Report Share Posted January 5, 2007 more good info from Thanos: somewhere else he states that the factory believes the best Front to Rear ratio with 505 springs is 1:3 (eg 100lb" and 300lb"), whereas he has found a ratio of 1:2.5 is better (eg 120lb" and 300lb") for handling as log as you increase front camber to at least 2.5 degrees, which would probably occur if you lowered a 505. yeah i'm not too sure about that ratio, i'd go the other way. the 505 turbo has always seemed too soft in the rear when your asking a lot IMO. maybe like a 100lb" and 350lb"? a while back i cut one coil off the front turbo springs. it seemed to lower the car the 'perfect' amount, not too low, not stock rally car height. it still had a great ride, but was more responsive, and had 'sharper' steering. now i know this is pretty hoopty, but i had a wood box in the trunk with 2 subs, and 2 amps. the box was super heavy, and it lowered the rear so it was about equal with the front. well, it looked great, but as you could imagine: track car in the front, citroen DS in the back. so i decided to ditch the sub box, and cut the rear springs. the guy who cut the rear springs cut one coil (as i asked), but also heated up the coil so the cut side of the spring was 'flat'. when i picked the car up, it was a bit lower then i expected (came to about a 3 inch drop in the rear, so the rear tire is well into the fenderwell) but i was curious to see how it would handle. surprisingly enough, it's really really balanced (i would say its an improvement over stock handling). the 'lowering ratio' seems stiffer in the rear over the stock spring ratio. when driven hard, the handling is really similar, and if anything, it has less understeer (which would make sense). Rabin, i'd be curious to see what you have to say about the F+R spring rate ratio, and how you think it could be improved (if at all). Quote Link to comment Share on other sites More sharing options...
Johnny Posted January 5, 2007 Report Share Posted January 5, 2007 Here it is, just change the extension to .xls I get the F:R ratios to 1:2.44 std and 1:2.13 with just the front springs cut 1 coil. And F:R 1:2.42 when both front & rear are cut 1 coil. Springrates2.txt Quote Link to comment Share on other sites More sharing options...
Metako Posted January 13, 2007 Report Share Posted January 13, 2007 Good work Johnny! I've just measured some 604 rear springs and they had 16mm wire which would be a useful upgrade (if coils were cut) on the 15.5mm wire used on GTi's and Turbos. I also went for a ride today in a 504 which has been lowered using springs on the front that had 14.5mm wire and about 4.5 coils and it wasnt too hard, just nice and firm. The owner said they were new Holden (GMH) Commodore "Race springs" with one coil cut, so I will try to follow up where to buy these, though I think I will still try cut 14mm 604 springs first as soon as I get the one I am waiting on. The 504 owner was also using Konis which he got from the US from ebay. They seemed to work really well at damping the harder springs. Quote Link to comment Share on other sites More sharing options...
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