After the next setup FF,the half n half,how are you goin to set up the diff?? The static slip? Ideally,would you set it 75 lb/ft? Let us know tomorrow when your done brother. Appreciate the time and effort you put in here for the boys.
Would 75 lb/ft of static drag be enough to impact, noticeably, 0-100kph times for a stop-light racer?
No, for a roadie on road tyres, 75 lb/ft with the 40% (both ways) GT4 diff is too tight. I'll leave it at 35 lb/ft if it's still over 50 when set half and half staggered. If half half split puts it to 45-50, I'll do that. Drag racing... is that when boys dress up as girls and run really fast? Not something any Ferrari is much good at.
well thats because boys usually are bigger boned , so the dresses are very tight , and this results in slower times. .
The ramp angles combined with excessive static preload, on a road car with a tight turning circle, tend to promote chatter when turning slowly. A race car typically has a reduced turning lock (wide wheels/brake ducts etc), so it's ok. A good oil can reduce or eliminate the chatter, but I'd rather avoid the cause, than attempt to fix the symptom. Anyway, ran out of time to play with the GT4 diff, so put it in with 36 lb/ft preload. I've got another in bits on the bench, and I'll do the stacked/staggered/half half test again some day soon.
O.K. and chatter does what besides make noise? What happens to how a car behaves when "too Tight" that is what is important?
Not much, other than excessive rolling resistance on lock (try pushing it around the garage!) Chatter causes shock loads to the drive line, and is uncomfortable and unnecessary. Let's not get all rocket science like over a diff.... Go karts don't have them, nor do Aussie V8 supercars.
I would definately put all the friction surfaces into play for a track car. I'm working on obtaining a quote for alternate angle ramps (I am a rep for Modena Engineering in the States). As stated prior, the downside to too much diff clutch preload is increased potential corner entry understeer. Best, Rob
Are you really, I wondered who he used over there. Maybe I could get stuff from you, because he won't answer his phone and when I go there he dodges all the questions, if he's there (usually away or out). I HAVE had a few 360 Diffs off him, and some 360 gears too, but FRIKKIN hell he's hard to deal with!
Cool on the ramp angles project I want to try playing with this. Can you compensate for the entry understeer by trail braking and jumping on the gas as early as possible? Or does a ramp angle change give you the benefits without the corner entry understeer negative?
a quick google gets this... which should help you get your head around it. http://icpcitation.com/variloc_tuning.htm http://icpcitation.com/variloc_theory.htm
to rebuild a rear end, ring and pinon for a pf cab 2, upon disasembly of the car we notice it had WAY TO MUCH play due to a bad bearing probably,so we need ring and pinnon, don't know the ratio yet, on monday i will take it appart and post pics you know i did a search and found nothing about this, i'll try some more and if not, i will open a thread about 250 rear ends
Good Idea. In the mean time, contact Symbolic and/or DK Engineering for parts and good information. I think I have a manual somewhere too..... need to have a look.
THANKS, and the manual would be of GREAT assistance!!, i'll take pics on monday, and start a thread about it with pics and a detail report
Actually, the diff is stock set-up...zero preload. Ernie is rebuilding his G Box in my garage at his pace and leisure. I'm just looking over his shoulder since I've done it a half dozen times and the comraderire is fun. I think he should shim up the diff to see what happens but he is thinking leave it stock or stagger plates mostly because he is at that point in a project where he just wants to find the time to finish it and the weather is getting really good in So. Cal....
I really am working on this thing at a turtles pace. But as FBB said I do want it back on the road as summer has arived in sunny So Cali. I'm just gonna stagger the plates and clutches. My car is going to live the vast majority of it's life on the street, so I'm not so concerned with exit corner speed as if it were a track only car like FBB's 348. ------------------------------------------------------------------------ However on a side note. While I was putting the lay shaft back together I noticed something interesting on the synchronizer sleeve. There are are notches on the under side, the side where the teeth are, that the pad and knuckle for the synchro sleeve fit in. One of the notches is deep, and the other two are more shallow. When putting the sleeve on, you need to make sure that it goes on properly so that it can side over the synchro rings and gear properly. Now for what I noticed. If you put the sleeve on one way, pad and knuckle fit into the deep notch. However if you rotate the sleeve the other way, one tooth, the pad and sleeve fit into the smaller notch. When I have the sleeve positioned so that the knuckle was in the deep notch, it took a bit more force to get the sleeve to slide over the gear. When I rotated it so that the knuckle was in the shallower notch is took less force to move the sleeve onto the gear. Now I'm thinking that having the sleeve positioned so that the knuckle is in the deep groove yeilds to the notchyness of the 348 gear box. I am seriously considering setting it up so that the pad and knuckle are sitting in the shallow notches. My thinking is that this will take the notchyness out of the gearbox and lead to smotther shifting. But before I do this, I would like to find out if the smaller notches are a result of machining, or were they put there on purpose, and as in typical Ferrari fashion they don't tell anyone about it. My concern would be that if I did it would pop out of gear, or if I wanted to put it in neutral the sleeve wouldn't want to cooperate. It's seems like it would be fine, but what do you guys think?
I think that you may be on to something. DO IT FOR THE BROTHERHOOD! EDIT: one of the 550 drivers, I think in Kuwait right now, mentioned that his transmission had been rebuilt by an old Ferrari pro to shift fast and shift smoother than any transmission that he'd ever used...one has to wonder what the old pro did.
