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Thread: Big problems shock absorbers Bilstein B6

  1. #106
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    Quote Originally Posted by Johnm400 View Post
    lol, be hard to do with the mountings. Seriously though, im wondering if Bilstein are machining them back to front. It does seem strange that the fronts and rears are exactly too low and high by the about the same amount
    Can you post some measurements? Circlip position as supplied, as corrected etc may help others identify if they have the same issue.

  2. #107
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    Quote Originally Posted by samdale View Post
    Can you post some measurements? Circlip position as supplied, as corrected etc may help others identify if they have the same issue.
    I already did. The fronts need to be 10mm higher than they are supplied at and the rears 12mm lower.

  3. #108
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    Some thoughts.

    There has been no change in Bilstein Sport units for the MKIV in years. I bought several sets this year and all are the same as ones bought ten or more years ago. Possible issues that come to mind. Incorrect seat castings supplied. (Unlikely, check the casting numbers on them). Front / rear springs mixed up. (Seen this before). Tired springs that have taken a set. (NEVER seen this with Supra stock springs).

    Bilstein Sports used with stock springs lower the car the car front and rear between 10 and 15mm. A spring seat 10 mm lower does NOT lower the car by 10mm. It lowers it the geometric ratio of the bottom arm length from inner bush to outer ball joint relative to the damper mount hole in the arm. The ratio is different front to rear. A ruler on a bottom wishbone or rear lower arm, preferably off the car, will give you that ratio. I can't remember it without referring to my notes.

    Re gassing Bilsteins needs a specialist muffle jig, although I have converted them to a Schraedar valve in the past.

    You need to machine new circlip grooves, not use a spacer, the circlip retention depends on the seat encompassing the clip. I machine new grooves all the time for custom set ups.

    Finally I *THINK* if you use Soarer springs on the Supra Bilstein Sport dampers you get the effect you are discussing. The best tech advice comes from Bilstein themselves in Germany, but the tech guys mainly only speak German.

    Some generic fitting reading: https://www.bilstein.com/uk/en/blog/...tion-mistakes/

    Some interesting reading on suspension technology generally implemented after the MKIV production life: https://www.zf.com/master/media/en/corporate/m.../dmpfungsmodulefrpkw.pdf

    Finally, having to have Bilstein machine grooves at different heights to use a supposedly stock MKIV TT spring set on stock Bilstein Sport dampers smells extremely fishy to me, I think the real issue has not really been discovered here.
    Regards, Chris Wilson. No PM's PLEASE, use e-mail!
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  4. #109
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    Quote Originally Posted by Chris Wilson View Post
    Some thoughts.

    There has been no change in Bilstein Sport units for the MKIV in years. I bought several sets this year and all are the same as ones bought ten or more years ago. Possible issues that come to mind. Incorrect seat castings supplied. (Unlikely, check the casting numbers on them). Front / rear springs mixed up. (Seen this before). Tired springs that have taken a set. (NEVER seen this with Supra stock springs).

    Bilstein Sports used with stock springs lower the car the car front and rear between 10 and 15mm. A spring seat 10 mm lower does NOT lower the car by 10mm. It lowers it the geometric ratio of the bottom arm length from inner bush to outer ball joint relative to the damper mount hole in the arm. The ratio is different front to rear. A ruler on a bottom wishbone or rear lower arm, preferably off the car, will give you that ratio. I can't remember it without referring to my notes.

    Re gassing Bilsteins needs a specialist muffle jig, although I have converted them to a Schraedar valve in the past.

    You need to machine new circlip grooves, not use a spacer, the circlip retention depends on the seat encompassing the clip. I machine new grooves all the time for custom set ups.

    Finally I *THINK* if you use Soarer springs on the Supra Bilstein Sport dampers you get the effect you are discussing. The best tech advice comes from Bilstein themselves in Germany, but the tech guys mainly only speak German.

    Some generic fitting reading: https://www.bilstein.com/uk/en/blog/...tion-mistakes/

    Some interesting reading on suspension technology generally implemented after the MKIV production life: https://www.zf.com/master/media/en/corporate/m.../dmpfungsmodulefrpkw.pdf

    Finally, having to have Bilstein machine grooves at different heights to use a supposedly stock MKIV TT spring set on stock Bilstein Sport dampers smells extremely fishy to me, I think the real issue has not really been discovered here.
    Chris, thanks for your input.

    Quick point. Side by side, the Bilstein seat height to bottom bolt eye distances are different than the original Toyota shocks. The fronts are shorter and rears longer, Surely this has to have the effect of lowering the front and raising the rear because the spring is sat at a different height?

    Take the fronts for example, surely if the distance from bolt eye to spring seat is shorter then its has to lower the ride height? I dont see how it cant?

    And the rears, if the distance from bolt eye to spring seat is longer then it surely has to lift the ride height?

  5. #110
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    Correct it will put rake on the car. the fronts lower the front, the rears raise it (a tiny bit due to the geometry of the arms).
    Regards, Chris Wilson. No PM's PLEASE, use e-mail!
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  6. #111
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    Quote Originally Posted by Chris Wilson View Post
    Correct it will put rake on the car. the fronts lower the front, the rears raise it (a tiny bit due to the geometry of the arms).
    Chris, im now even more confused. You agree with my last post so how can this be?

    Do you think my Bilsteins were machined wrong from the factory? (Bilstein say the measurements were all correct).

    Luckily the car is sitting perfectly now that they machined new circlip grooves but it would be interesting to get to the bottom of this.

  7. #112
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    Sorry, typo / brain fade / distracted, the rear Bilsteins will, with a given spring, raise the rear a tad. just the front will be lower. I believe they correctly saw that with the well loved lowering springs the rear of the car would be put into very poor geo, the MKIV does NOT like to be run low at the back, the geo goes to pot faster than at the front, and there's not a lot of travel anyway. I don't think there's anything wrong with your dampers.
    Regards, Chris Wilson. No PM's PLEASE, use e-mail!
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  8. #113
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    Bump

    Quote Originally Posted by Iky View Post
    Theres a little spacer type thing on top of the rod. Is this correctly fitted?
    Which way up do these little collars go?

    Also, there's 2 different sizes of collar, what goes where?
    Last edited by samdale; 18-09-19 at 19:08.

  9. #114
    I'm part of the furniture Authorised Trader Chris Wilson's Avatar
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    Thicker little bit at the bottom, toward the lower end of the damper, but it won't affect the ride height.
    Regards, Chris Wilson. No PM's PLEASE, use e-mail!
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    Suspension development and geometry specialist, Supra work and other cars too! 07971-952084
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  10. #115
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    Quote Originally Posted by Chris Wilson View Post
    Thicker little bit at the bottom, toward the lower end of the damper, but it won't affect the ride height.
    I thought as much. When I was playing around with them it seemed to make sense and the bump stop fits over it snugly. Next question is if the bump stops need a haircut when being used with lowering springs?

  11. #116
    I'm part of the furniture Authorised Trader Chris Wilson's Avatar
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    DO NOT cut the bump stops. The car should never be on the bump stops except in extreme situations, like a hump backed bridge taken far too fast, if there's not at least 1.5 inches clearance static, it's too low. Once the damper tops hit the bump rubbers the spring rate goes insanely high with unpredictable effects on handling. I see plenty of mashed up bump rubbers, the cars invariably drive like dogs. Constantly running on the bump stops will put insane loads into the suspension components.

    As an aside there have been times when I have deliberately designed a suspension system to run permanently on specialised Koni race bump stops, they used to be available in many different lengths, shapes and durometer readings. The last time I did this was in a one make BMW championship series for a local guy. He is a very capable racer but was always finishing down the field. He said springs and dampers were supplied by the series and could not be changed. He was sure the front runners cars handled very differently to the also rans. I watched videos of the series and saw the also rans were rolling about in the corners, the front runners barely rolled at all. ARB's were also fixed spec. So what were they doing?

    I read the rule book analytically and worked out the fast guys must be running trick bump stops to increase spring rate via that means. Nothing was said about bmp rubbers. Yippee, got `em! He tried various trick rubbers and eventually won the championship. Was it cheating? No, no more so than a factory TVR racer that had a transaxle fitted. The scrutineers tried to fail it, but the rules just said that the original gearbox casing must be used in its original position. it was, but the internals were absent with the input shaft welded to the output shaft, taking drive from the crank straight through to the rear mounted transaxle. Another wheeze was the regs said a lightweight propshaft could be used. With transaxles the inertia in the prop makes rapid gear changes hard on the gearbox / transaxle, so it became the first UK race car to run a (hugely expensive back then) carbon fibre propshaft. Again the scrutes hated it but what could they do...? The thing wiped up for 18months with the hugely talented privateer Steve Cole at the wheel as the regulations were deemed to have to be kept the same for a minimum of that period. That's what race designers do first, read the regs and look for loopholes Even little things helped it. It had to run the original roof, a soft top. It flapped about creating drag, so they doped it with aeroplane wing cloth dope until it was a rigid as a steel hard top, but far lighter. The chief engineer for TVR at the time was a Kraut, Chris Schirle, ex F1, the guy was awesome, he taught me a lot about rule books and interpretation He'd probably be good for Boris in the Supreme Court right now Trick bump stops are kludges strictly for the race track though, where "proper" suspension more suited to the needs is banned by set rules.
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    Last edited by Chris Wilson; 19-09-19 at 15:07.
    Regards, Chris Wilson. No PM's PLEASE, use e-mail!
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  12. #117
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    Hi, i've got a very similar problem to what is being described here. Basically the rear sits sky high but the front is really quite low (to the point of scrubbing). Furthermore, the rear nearside is much higher than the offside. These are billstein dampers with eibach lowering springs. the car is a TT, i've checked the spring part number and they're correct and also fitted the right way round.

    Is there a common fitment problem that might cause the rear to sit much higher? I've read about slackening the control arm bolt, refitting, then tightening up the bolt once the car is on the ground?

    picture of nearside front and rear attached.

    IMG_20190824_201009.jpg IMG_20190824_201000.jpg

  13. #118
    I'm part of the furniture Authorised Trader Chris Wilson's Avatar
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    If you still have the stock rear springs fit those and see how it sits?
    Regards, Chris Wilson. No PM's PLEASE, use e-mail!
    Race and performance road car servicing and preparation in north Shropshire. Race and road car engine building and tuning.
    Suspension development and geometry specialist, Supra work and other cars too! 07971-952084
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  14. #119
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    Quote Originally Posted by Chris Wilson View Post
    If you still have the stock rear springs fit those and see how it sits?
    Alas i don't. the car came with a random set of mismatched coilovers in the boot, but already sat on the bilsteins.

    Odd that there's so many threads on cars sitting high at the rear on bilsteins! Suspect it's like you mentioned on the phone yesterday, there's an error in fitment that can cause this somehow.

    if not, i may send you them to machine an additional circlip groove into or something.

  15. #120
    I'm part of the furniture Authorised Trader Chris Wilson's Avatar
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    I want to see them ON THE CAR before machining anything, something very odd here. How much compression is on the rear springs when fitted woth the dampers off the car? They will need a bit of existing preload if we are going to move the lower seat lower. Are Eibach springs a common denominator by any chance?
    Regards, Chris Wilson. No PM's PLEASE, use e-mail!
    Race and performance road car servicing and preparation in north Shropshire. Race and road car engine building and tuning.
    Suspension development and geometry specialist, Supra work and other cars too! 07971-952084
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