vagmag (05-10-15)
αντιγράφω από το πιο πάνω θέμα σχετικά με τα διαφορικά , κάποια πράγματα που φάνηκαν ενδιαφέροντα.
Σχετικά με το διαφορικό από Μ3 Ε46/Ε92after driving (and drifting) some thousand miles with my stock gkn viscolok unit i was sure to need a proper torque sensing clutch-type lsd which will react and lock/unlock way quicker and with direct connection to gas pedal movements. the viscolok is a really slow performer who locks and unlocks slowly and smoothly.
quite ok for non-performance street driving and slippery, snowy road conditions. but annoying when driving on the track or drifting the car where you need direct control and quick response of your rear axle behaviour.
the stock diff is a speed-sensing unit. it has no accel/decel values as it has no ramps where the diffaxles run up and down generating pressure depending on the torque applied, as in a torque-sensing clutch-type lsd design.
with the stock unit you necesserily need different wheel speeds over a certain amount of time (meaning: one spinning wheel) to activate the sheerpump which generates the pressure on the clutches. the engagement is smooth... as is the disengagement.
so one wheel spins for a short while, diff starts locking smoothly (and can lock up to 100% which means no matter how big the torque difference left/right will get, it remains locked), then after locking a while there is of course no more difference in wheel speeds and the sheer pump will disengage and releasing the pressure on the piston. so the diff opens up smoothly. if there is still a huge difference in traction l/r it will again start from the beginning... on and on...
so with this unit you will have no corner entry and mid understeer at all (except the amount of preload it is set to.... this is what you feel when turning in low speeds and a lot of customers are complaining about... also here in this forum).
but on corner exit, when hitting the gas quite hard, this unit will not lock immediately but let the inner wheel spin for a while
Σχετικά με το διαφορικό από Μ5 Ε39and last but not least i have an old friend of mine here as well. an "old" zf lsd unit from a M5 E39 which also fits into the E92 rear axle. but as this unit locks quite weak in stock configuration, i am massively modifying this unit to fit more clutchpacks and/or use different ramp angles. this unit is performing well if modified correctly
any clutch-type lsd with preload does the same... and you can change the amount of preload by changing the cupsprings.
the downside of preload is understeering! the more preload, the more understeer!
yes i have some m5 e39 units here. they come with only 2 clutchpacks and a 2-way setup which does 25% lockup on both, accel and decel.
and it has pretty much preload.
i developed a rebuild kit that fits plug and play with the double amount of clutches. so it locks 45% in both directions. clutches are higher quality than standard, too. if you want preload and/or even more lockup you need some exchange parts like different pressure rings, modified topcaps...
so the basic unit itself is a great basis but it comes as standard with a pretty low locking setup and wears out quickly.
too much lockup on decel means it has some turn-in understeer. but bevor turning in there normally is a certain need to brake hard. and if you do that (especially in a quick corner, where you cannot brake on a straight line) the rear end gets nervous and wants to spin the car. therefore you have the decel lockup that helps keep the car straight and stable under hard braking. if you have dsc switched on or dont brake hard anyway you don't need decel lockup. if you drive and brake hard on quick racetracks, you definitely do need it to be quick!
turn in understeer then has to be reduced via other setup parameters (coilovers, swaybars, camber, square tire setup, ...).
Ερώτηση σχετικά με street drifting
A) at least 45% with medium preload or even a higher lockup like 65% would be quite good!
B) in general the best would be as much clutchpacks and as steep ramps as possible.
the maximum you can get with the zf is 6 clutchpacks and according to the locking value you want to have you (or i) need to choose the ramp angles required. i have super steep ramps here from 85°, 80°, 75°, 70°, 65°... and down to 30°.
C) it always depends on your focus and budget. most people want a well working lsd that locks well, has not to be rebuilt too quickly and (mostly) is still cost effective.
depends on the basis. a setup with 4 clutchpacks can be built very easily in a E39 M5 stock lsd core. if you want 6 clutchpacks, the lsd core needs to be removed (ringgear, bearings) and cnc machined. then everything needs to be installed again.
yes, you can possibly say "more lockup = more sideways fun" although it is a little more complex of course.
ερώτηση σχετικά με ποσοστό εμπλοκής στο άφημα του γκαζιού... no! more lockup always means more understeer! if the locking value is higher this means the axle is locked more/longer and if two wheels are connected together and rotate at the same speed this means understeering! no matter of we speak about acceleration or deceleration. pretty easy...
and, to answer your next question in advance already: "more lockup = more sideways fun" is also true, because if you hit the gas (too) hard midway a corner both wheels spin and the car will slide sideways.
ερώτηση σχετικά με την προφόρτιση ή preload
preload is static lock!
lock = understeering!
dynamic lock (generated via the ramps and applying a force on them) can be reduced or stopped anytime via applying less force or hitting the clutch pedal. the static lockup generated via the preload will always stay there!
but preload helps smoothing the load changes (while hitting and lifting the gas pedal). the lsd reacts more predictable. and the cupspring used to generate this preload can balance the wear of the clutches that are getting thinner after time.
i also build lsd setups without preload for some of my racing customers. if you know how to drive these setups and don't mind the short rebuild intervals this is a pretty perfect setup for experienced race drivers.
i currently also drive a setup without preload in my street-driven e92 because i like the extreme load change behaviours ;-)[/I]
gnvsls (06-10-15)
Προσανατολίζομαι λοιπόν στο να φτιάξω ένα διαφορικό, με δισκάκια, 45% στην επιτάχυνση και 45% στην επιβράδυνση , με μικρό ποσοστό προφόρτισης.
Αν υπάρχουν φίλοι από εδώ μέσα , που έχουν κάποια εμπειρία ή γνώσεις , θα εκτιμούσα τη γνώμη τους, όπως και από όποιον καταλαβαίνει περισσότερα.
Να διευκρινίσω, ότι δε θεωρώ κακό το διαφορικό του Μ3, ούτε ότι μπορώ να το φτάσω στα όριά του. Έχω καταλάβει πως συμπεριφέρεται στο δρόμο και μου είναι αρκετά διασκεδαστικό, αν και νομίζω ότι καταλαβαίνω αυτήν ην ανεπαίσθητη καθυστέρηση στο απότομο βύθισμα του γκαζιού. Επίσης μάλλον σε επιθετική οδήγηση σε δρόμο και όχι πίστα μάλλον είναι πιο εύκολο να πας γρήγορα.
Από την άλλη μάλλον θέλω να δοκιμάσω κάτι "καλύτερο" , πιο άμεσο για υπερστροφή ισχύος.
vagmag (09-10-15)
M5 E39 ...
Οι σκέψεις μου είναι λίγο πιο κοντό βήμα ( 3,62 ) για ακομα καλύτερο άρπαγα ( της 3ης σχέσης ) ..... , κ να γίνει το διαφορικό 45% ή 65% .
Το 65% κοστίζει περισσότερο .
Η χρήση είναι κυρίως στο δρόμο , όπου προσπαθώ να υπερστρεφω παντού ακομα και τώρα με το μαμά βήμα αλλά κ το μαμά διαφορικό .
Το θέμα που διαβάζω είναι το παρακάτω κ προσπαθώ να καταλάβω .
https://www.m3post.com/forums/showth...=788992&page=9
Γράφει λοιπόν :
B) in general the best would be as much clutchpacks and as steep ramps as possible.
the maximum you can get with the zf is 6 clutchpacks and according to the locking value you want to have you (or i) need to choose the ramp angles required. i have super steep ramps here from 85°, 80°, 75°, 70°, 65°... and down to 30°.
Έχει σχεσει αυτό με το 2 που γράφεις κ εσυ ;
Μιας κ δεν έχω βρει κάποιον άλλον να απευθυνθώ , κατέληξα σε αυτόν ... Να μου φτιάξει .
Τώρα μένει να του εξηγήσω αυτό που θέλω .... Ή αν έχεις κ κάποιον άλλον να προτείνεις θα βοηθούσε κ αυτό !
Μονο οταν θα καταλαβεις που παει..Λες δεν γ@μιεται,ειναι το ταξιδι που μετραει....
vagmag (10-10-15)
Διαβάζοντας αυτά που έγραψες κ βλέποντας το παρακάτω βιντεάκι ...
Καταλαβαίνω οτι :
Α) το διαφορικο που εχω τωρα ειναι 1.5way , πράγμα που με καλύπτει για τη χρηση που θελω ( υπερστροφικη οδήγηση κ οχι αγωνιστική ) ,
Β) με τα νέα δισκάκια κάνω πιο σφιχτό το διαφορικο ( 45% ειναι αρκετό )
Γ) η προ φόρτιση ειναι καποιο εσωτερικό "ελατήριο " , κ δεν ειναι απαραίτητα κακή
Δ) για να γινει πιο επιθετικό , πιο άμεσο το διαφορικο , πρέπει να αλλαξουν΄ οι γωνιές της ράμπας . Τι μοίρες εχει τωρα κ σε τι μοίρες θα πρότεινες να παει ;
Αν θελεις διόρθωσε με στα παραπάνω που έγραψα .
BILL007 (11-10-15)