Announcement

Collapse
No announcement yet.

Should new Bilstein sports feel this still.

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • hardtailer
    replied
    Originally posted by caneswell View Post
    I've measured the motion ratio whilst I was there at ~0.62 (the ~0.9 numbers stated online are for the centre of the contact patch, so quite different at the edge of the rim.
    Which travels did you measure and how did you calculate your motion ratio?
    Since the edge of the rim is solidly attached to the contact patch the motion ratio at the edge of the rim has to be the same.
    One of main characteristics of a McPherson strut suspension is that the motion ratio is almost 1, apart from that the motion ratio of 0.9 stems from official BMW documents, so it would be a shame if you'd base further calculations or decisions on a wrong assumption.

    Leave a comment:


  • stevesingo
    replied
    Mine is about the same, although I have the Sport Evo front fenders/wings which have a 10mm larger arch, so I would say I am using 10mm more of the available wheel travel than your good self.

    Leave a comment:


  • caneswell
    replied
    565-570mm left to right (probably not the most level driveway) How does that compare? Wheel looks to be pretty concentric in the arch.

    Leave a comment:


  • stevesingo
    replied
    Good info. What is your ride height from bottom of wheel rim to wheel arch?

    My ride quality on 155lb/in front spring at stock ride height is pretty good mostly. Where I do notice an imbalance front to rear is when hitting compressions at speed. The front does feel quite firm compared to the rear. I think I will conduct the same test as you at the weekend.

    Leave a comment:


  • caneswell
    replied
    OK so measuring at the wheel rim (16x8 ET23) i'm getting ~105mm of travel from rest to fully extended on my standard (>170k mile!!) front springs.

    I've measured the motion ratio whilst I was there at ~0.62 (the ~0.9 numbers stated online are for the centre of the contact patch, so quite different at the edge of the rim)

    This means I'm sat at 65mm of shock compression from a total 82mm. Giving me 28mm of wheel rim travel before they contact, which doesn't seem to be very much and the bump rubbers must be very soft as I'm not noticing a sharp increase in rate when driving. Certainly seems like you will have to trim them when lowering. I'll see if my Bilstein contact has any feedback as to why they are like this.

    Leave a comment:


  • stevesingo
    replied


    I did some Googling and it would seem the Bilstein bump stops are about 75mm long



    And if this E28 example is anything to go by, available in different hardness.




    Leave a comment:


  • nauqneyugn
    replied
    So basically I need to trim my Bilstein's bump stops!

    Leave a comment:


  • caneswell
    replied
    The Bilstein rep also stated that their shocks could be compressed a further 65mm on the bump stops up to their max test load of 5000N, so they must be significantly longer than the stock versions...

    Why are they designed to basically run on their bump rubbers??

    Leave a comment:


  • stevesingo
    replied
    Stock Bump Stops measure 52mm

    Leave a comment:


  • stevesingo
    replied
    I suspect that almost all of the 82mm is used up. 82/0.926 MR is 88.5mm of wheel travel. If you measure your ride height from bottom of the wheel rim to the wheel arch with the car sat on flat ground, jack it up and repeat. I'd besurprised if it is less than 75mm.

    I have a set of stock bump stops in the garage. I will measure them and report back.

    Leave a comment:


  • caneswell
    replied
    I've also had confirmation from Bilstein that the B6 34-003350 travel length before bump stop is 82mm.....will check how much of that I'm using tonight.

    Leave a comment:


  • caneswell
    replied
    It does seem that manufacturers are unwilling to offer kits with a similar front to rear stiffness ratio as stock, especially in Europe. I guess it's playing it safe towards an understeer balance. The closest combination I've found, by requesting the rates from various manufactures, would be to use the following:

    Front = Vogtland E30 4 cyl 951010VA (Front their 951017 kit) = 24N/mm (137lbf/in) - Free length is stated as 260mm on the TUV certificate
    Rear = KW E30 Touring 22061 = 65.2N/mm (372lbf/in) - 200mm free length

    I'm not entirely sure where these will end up regarding ride height yet, but sure it can be tweaked with spring pads. I don't want to go too low.

    The TUV certs are here:
    KW (ST) = http://docs.kwsuspension.de/ga20001-1199-12.pdf
    Vogtland = http://shop.vdf-springs.com/media/pd...86-96-FBKB.pdf

    Although from these numbers I don't see how the Vogtland supplied spring rates can work out. They seem almost identical to the H&R springs at ~188lbf/in....But two different people at Vogtland gave me similar numbers...

    Leave a comment:


  • stevesingo
    replied
    In lb/in

    H&R Sport 29663-1 - 188/285lb/in- -1 3/8 Euro Market All 4cyl. Not M3 Specific, so presumably the ride height drop is referenced from a non M3 4cyl model)
    H&R Sport 29664-1 - 188/285lb/in- -1 3/8 Euro Market All 6cyl. I had a set measured at 200/285 which is consistent with the 12.5mm dia wire as opposed to 12.0mm of the 29663.

    H&R 29818-1 - 256/319lb/in- -1 Euro Market All 4cyl Cabrio
    H&R 29729-1 - 171/313lb/in- -1 Euro Market All 4cyl Touring

    H&R Sport 50406 - 188/342 -1 front -0.75 rear USA Market M3 Specific

    That is all good info

    Leave a comment:


  • caneswell
    replied
    Great info Steve

    As you know I've been looking into this a bit recently too. With regard to the US only 50406 H&R springs I've had confirmation from H&R reps in Europe that these are different to the EU offered parts and aren't available in Europe at all.

    I also received the following info from H&R in Europe regarding spring rates:
    29663: 33N/mm front and 50N/mm rear
    50406: 33N/mm front and 60N/mm rear
    29664: 33N/mm front and 50N/mm rear
    29818-1: front 45N/mm, rear 56N/mm

    29729-1: front 30N/mm, rear 55N/mm

    Confused though as to why they state the same rate for 29664 and 663 as the wire diameters are different.....



    Leave a comment:


  • stevesingo
    replied
    Bilsteins

    As far as I understand there are the following dampers available in Europe from Bilstein for the E30.

    Front_______Rate___Wheel Rate___Application
    34-003350_233/75.5___200/65____M3 sport/325i HD
    34-046926_300/300___257/257____GpN
    34-236406_280/150___240/129____GpN Rally


    Rear_______Rate___Wheel Rate___Application
    24-020275_160/55____180/62____M3 sport/325i HD
    24-060653_140_60____157/67____M3 sport/325i HD
    24-000642_200/200___225/225____GpN
    24-233267_260/120___292/135____GpN Rally

    I believe in the USA the B6 are known as HD and the B8s known as Sports, for use with lowered suspension.

    As you can see the same dampers are used for the 6 cyl cars and the M3, only the application differs.

    In the table I have converted the damper rates to damping rates at the wheel using the same formula as used for the spring rates;

    mr*mr*dr

    where

    mr=motion ratio
    dr=damper rate

    The motion ratio for the front damper is the same as the spring at 0.926 as the spring sits concentric with the damper. For the rear, the damper is separate from the spring and further from the pivot point than the wheel so the motion ratio is 1.06.

    In view of the problem that the front seems too stiff, even in my case where the rear sprung wheel rate is higher than the front, there must be cause for this. My next step is to measure how much of the damper travel I am using when the car is static, then remove the insert, measure the full damper travel (the only data I can find is for 34-003350 Front B8- 597mm extended and 515mm compressed =82mm travel)and bump stop length and calculate how much travel is remaining before the bump stops come in to play. From what I can see on the web, the bump stops seem to be about 3-3.5” long, so I would hope I have at least 3” damper travel before I come in to contact with the bump stops.

    When you look at the stock bump stops, they are about 1.5” long. When we consider the lower spring rates and damping rates of a stock car in comparison to one with Uprated springs and dampers, I can’t see any reason why we should need a longer than stock bump stop.

    Leave a comment:

Working...
X