504 rally car/604 donor car
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  1. #1
    Fellow Frogger!
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    Default 504 rally car/604 donor car

    Well, a friend of mine decided he is joining the frog brigade and asked me to help him build (or rather come up with a suggestion for) a 504 rally car. I am always happy to have new playmates so I gave him a couple of ideas last week and today he called with an update. He located a 504 rally car candidate and a 604 donor car. He already put small deposits on both vehicles and if it is a go he will be picking them up on Friday.

    The candidate rally car is a 1970 or 71 504 sedan, with four on the floor but appears to have originally been a column shift as the e-brake is by the steering wheel and not in the center console. Original owner (!) accident free, rust-free body, interior kind of tired, but it’s to be replaced by buckets and rollcage. Best shifting, most quiet transmission he recalls in a 504. The motor, he was told, is from an early 505 and looks like an XN1 to him and has a single carburetor. He is not sure what the motor is, but it appears that the car may be the lighter version. Any way to find out the type of motor and the weight of the car? (frame and engine numbers, etc)

    The potential donor car is a 1977 604 SL with automatic and carbs, leaking lots of tranny fluid but otherwise good, with great interior and 15 inch 505 alloys.

    Our main concern is to get the handling dialed in. The target is to get one to two degrees negative camber up front and slightly stiffer ride and a wider track in the back.

    Here is what we are thinking for the 504 suspension/steering set up:
    Front: 604 power steering rack and pump, crossmember, brakes, swaybar, struts, triangulation arms, basically the entire steering/suspension system except for springs and shocks. The springs will be similar to the STI but an inch and a half lower and around 20% stiffer (100 lbs/inch). Shocks will be Kayaba’s similar to the STI. Custom strut tower bar.

    Rear: 604 rear trailing arms, drive shafts and brakes, 19 mm sway bar. The springs will be similar to the STI but an inch lower and around 25% stiffer (285 lbs/inch). Shocks will be Kayaba’s similar to the STI but a bit stiffer.

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    15 inch 505 alloys all around with 195/60/15. I will also look for a J differential from a 505 to give it a bit more spunk.

    Do you see any problems with the plan or can you suggest alternative options?

    Thank you

    Thanos

    P.S. There is a whole lot of stuff left on the 604 and I have some ideas but I want to keep this post at a reasonable size, so I will post at another time regarding the 604 carcass.

  2. #2
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    Quote Originally Posted by Thanos
    Well, a friend of mine decided he is joining the frog brigade and asked me to help him build (or rather come up with a suggestion for) a 504 rally car. I am always happy to have new playmates so I gave him a couple of ideas last week and today he called with an update. He located a 504 rally car candidate and a 604 donor car. He already put small deposits on both vehicles and if it is a go he will be picking them up on Friday.

    The candidate rally car is a 1970 or 71 504 sedan, with four on the floor but appears to have originally been a column shift as the e-brake is by the steering wheel and not in the center console. Original owner (!) accident free, rust-free body, interior kind of tired, but it’s to be replaced by buckets and rollcage. Best shifting, most quiet transmission he recalls in a 504. The motor, he was told, is from an early 505 and looks like an XN1 to him and has a single carburetor. He is not sure what the motor is, but it appears that the car may be the lighter version. Any way to find out the type of motor and the weight of the car? (frame and engine numbers, etc)

    The potential donor car is a 1977 604 SL with automatic and carbs, leaking lots of tranny fluid but otherwise good, with great interior and 15 inch 505 alloys.

    Our main concern is to get the handling dialed in. The target is to get one to two degrees negative camber up front and slightly stiffer ride and a wider track in the back.

    Here is what we are thinking for the 504 suspension/steering set up:
    Front: 604 power steering rack and pump, crossmember, brakes, swaybar, struts, triangulation arms, basically the entire steering/suspension system except for springs and shocks. The springs will be similar to the STI but an inch and a half lower and around 20% stiffer (100 lbs/inch). Shocks will be Kayaba’s similar to the STI. Custom strut tower bar.

    Rear: 604 rear trailing arms, drive shafts and brakes, 19 mm sway bar. The springs will be similar to the STI but an inch lower and around 25% stiffer (285 lbs/inch). Shocks will be Kayaba’s similar to the STI but a bit stiffer.

    15 inch 505 alloys all around with 195/60/15. I will also look for a J differential from a 505 to give it a bit more spunk.

    Do you see any problems with the plan or can you suggest alternative options?

    Thank you

    Thanos

    P.S. There is a whole lot of stuff left on the 604 and I have some ideas but I want to keep this post at a reasonable size, so I will post at another time regarding the 604 carcass.

    That all sounds good, is this to be used on bitumen as it is being lowered?
    You will have a lot of negative camber on the front with the 604 arms AND lowering but would be OK with power steering.
    The 604 brake connections will be metric and the pipes will have a different flare to the early 504 so some work will be required there.
    All early 504s had the handbrake under the dash whether they were floor or column shift.
    Graham

  3. #3
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    Quote Originally Posted by GRAHAM WALLIS
    That all sounds good, is this to be used on bitumen as it is being lowered?
    You will have a lot of negative camber on the front with the 604 arms AND lowering but would be OK with power steering.
    The 604 brake connections will be metric and the pipes will have a different flare to the early 504 so some work will be required there.
    All early 504s had the handbrake under the dash whether they were floor or column shift.
    Graham
    Thank you for the response Graham.

    You are correct, the set-up I am describing is for bitumen (I am assuming you mean paved track) hence the reduced ride height. There are also two races annually on unpaved roads (the classic Acropolis being one of them) and for them we would swap springs and shocks to increase the height. One thought is to use the original 604 springs and shocks (I am assuming that this would raise it more than the stock 504 height) or standard issue STI springs and shocks. I am not sure what the 604 springs are like, I will calculate spring rates once I have them in front of me and I measure the coil thickness and count the number of active coils. We will then decide whether we will use them or the 505 components. What would be your preference?

    Regarding the brakes, I was thinking about swapping the ENTIRE 604 set-up including lines and e-brake. Will that work?

    Interesting about the e-brake location in early 504's, I never new that. Any guesses as to the weight based on the fact that it is an under dash e-brake, 4-on-the-floor model?

    As an aside: I am amazed by the depth of knowledge in this forum and I put this forth for everyone's consideration: Perhaps an "Ultimates" article can be co-authored by the five or more "guru's" (you know who you are) that goes sort of like this: The ultimate 205 GTI will have (motor, brakes, suspension, ECU, gearbox etc)... And compile a list like this for the 205, 504, 505, 306 etc. You can start with a couple of cars and keep adding to the list. Think of the number of people who will benefit from this information and the interesting cars built.

    Thanos

  4. #4
    Budding Architect ???? pugrambo's Avatar
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    the 604 brake lines will not fit into the 504

    the line for the rears in the 604 actually goes through the cabin of the car, i suppose you could do the same for the 504 but it would be better to use new lines with the double flares on them for the 604 brakes

    as for ride height, yes the standard 604 springs will raise the 504 at the front but the rear would still be about the same

    the 604 fronts are also fairly soft
    3 x '78 604 SL

    1 x '98 306 GTi6

    1 x secret project

    1 x '98 406 STDT troop carrier and i don't care if it stinks, i don't sniff it's arse Death by wank tank

    1 x '99 406SV 5spd wagon, time to burn more fuel

    1 x 1994 605 SV3.0


    WTD long range fuel tank for 605

  5. #5
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    Quote Originally Posted by pugrambo
    the 604 brake lines will not fit into the 504

    the line for the rears in the 604 actually goes through the cabin of the car, i suppose you could do the same for the 504 but it would be better to use new lines with the double flares on them for the 604 brakes

    as for ride height, yes the standard 604 springs will raise the 504 at the front but the rear would still be about the same

    the 604 fronts are also fairly soft
    The 604 springs are far too high and soft, my car was very high at the rear also when I tried this.
    1984 STi / 1985 early GTi springs are very good. The early ones will be probably too high.
    I don't think there is any basic weight difference between early and late 504s except that the later Australian ones have heavy intrusion bars in the doors.
    Of course air conditioning sun roofs etc will add weight. Any increases in the later cars would be due to this and other added equipment.
    Graham

  6. #6
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    Quote Originally Posted by GRAHAM WALLIS
    The 604 springs are far too high and soft, my car was very high at the rear also when I tried this.
    1984 STi / 1985 early GTi springs are very good. The early ones will be probably too high.
    I don't think there is any basic weight difference between early and late 504s except that the later Australian ones have heavy intrusion bars in the doors.
    Of course air conditioning sun roofs etc will add weight. Any increases in the later cars would be due to this and other added equipment.
    Graham
    Thank you Graham and Rambo. So here is the plan based on your feedback: I will go with the original ideas for paved track, switch to the 84/85 STI set up for dirt. (Would you know the wire thickness and the number of coils for these STI springs?) As for the negative camber, I like about one to one and a half degrees. Any suggestions what to do if it turns out to be way more?

    I will intitially attempt to go the economy route and use the entire brake set-up from the 604, e-brake, lines and all, and pass the rear brake lines through the cabin, which I actually prefer for safety reasons. (That was an unexpected bonus). If the lines look scetchy I will convert to the Goodridge connections, as I do have a few odds and ends laying around.

    Interesting about the 604 springs. I am assuming that since they are taller and softer they have more coils than the 504 or 505 springs. I wonder if by cutting them we can customize height and spring rates to something helpful. I guess I will know more once I have them in my hands.

    Picking up the cars Monday or Tuesday. I can't wait!


    Thanos
    Last edited by Thanos; 25th August 2005 at 07:18 AM.

  7. #7
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    Quote Originally Posted by Thanos
    Thank you Graham and Rambo. So here is the plan based on your feedback: I will go with the original ideas for paved track, switch to the 84/85 STI set up for dirt. (Would you know the wire thickness and the number of coils for these STI springs?) As for the negative camber, I like about one to one and a half degrees. Any suggestions what to do if it turns out to be way more?

    I will intitially attempt to go the economy route and use the entire brake set-up from the 604, e-brake, lines and all, and pass the rear brake lines through the cabin, which I actually prefer for safety reasons. (That was an unexpected bonus). If the lines look scetchy I will convert to the Goodridge connections, as I do have a few odds and ends laying around.

    Interesting about the 604 springs. I am assuming that since they are taller and softer they have more coils than the 504 or 505 springs. I wonder if by cutting them we can customize height and spring rates to something helpful. I guess I will know more once I have them in my hands.

    Picking up the cars Monday or Tuesday. I can't wait!


    Thanos

    Sorry, I don't have the specs for the STI springs but the fronts have two blue markings. These springs were also fitted to the 505 turbos and the early rally springs were about the same rate. I tried taking turns out of 604 springs but they still seemed too soft.
    Graham

  8. #8
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    Quote Originally Posted by GRAHAM WALLIS
    Sorry, I don't have the specs for the STI springs but the fronts have two blue markings. These springs were also fitted to the 505 turbos and the early rally springs were about the same rate. I tried taking turns out of 604 springs but they still seemed too soft.
    Graham
    Thanks, Graham. For reference, I believe the 505 springs you like have the following specs: Front 85 lbs/inch, rear 210 lbs/inch for the normal version ( STI?) 240 lbs/inch for the strengthened version (turbo?). I hope this is useful. By the way, you can calculate spring rates if you know coil thickness, coil diameter and active coils (number of coils that are free to move) by using the following formula:

    spring rate in lbs/inch = 11500000 times the coil thickness in inches to the fourth power divided by the coil diameter in inches to the third power, divided by eight, divided by the number of active coils.

    For example the front springs have 6.2 active coils, 13.25 mm thickness and 150 mm diameter. Using the formula we calculate 82 lbs/inch, which is really close to the measured 85 lbs/inch.

    And for people like me who have been away from school for a long, long time, 2 to the third power is 2X2X2=8, two to the fourth power is 2X2X2X2=16. To go from millimeters to inches divide by 25.4.

    This way you don't have to decipher the color code system and you can even use springs from other cars. You can also calculate the effect of removing coils on stiffness.

    Thanos
    Last edited by Thanos; 27th August 2005 at 04:06 PM.

  9. #9
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    Quote Originally Posted by Thanos
    Thanks, Graham. For reference, I believe the 505 springs you like have the following specs: Front 85 lbs/inch, rear 210 lbs/inch for the normal version ( STI?) 240 lbs/inch for the strengthened version (turbo?). I hope this is useful. By the way, you can calculate spring rates if you know coil thickness, coil diameter and active coils (number of coils that are free to move) by using the following formula:

    spring rate in lbs/inch = 11500000 times the coil thickness in inches to the fourth power divided by the coil diameter in inches to the third power, divided by eight, divided by the number of active coils.

    For example the front springs have 6.2 active coils, 13.25 mm thickness and 150 mm diameter. Using the formula we calculate 82 lbs/inch, which is really close to the measured 85 lbs/inch.

    And for people like me who have been away from school for a long, long time, 2 to the third power is 2X2X2=8, two to the fourth power is 2X2X2X2=16. To go from millimeters to inches divide by 25.4.

    This way you don't have to decipher the color code system and you can even use springs from other cars. You can also calculate the effect of removing coils on stiffness.

    Thanos

    Thanks for the info Thanos. Yes 6.2 turns are the ones. The early STis had 7.5 turns.
    Graham

  10. #10
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    Quote Originally Posted by GRAHAM WALLIS
    Thanks for the info Thanos. Yes 6.2 turns are the ones. The early STis had 7.5 turns.
    Graham
    The 7.5 turns STI springs sound the same as the 504 sedan springs which are rated at 70 lbs/inch . They are also made from 13 mm wire instead of 13.25.

    Thanos

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