[cstavaru]

First, I think that if you want the best track times, you should forget the gear-type LSDs and go with a clutch-type LSD. No one (with rear traction) is using gear-type LSDs in professional races.

This leaves you very few options.

If you are in Taiwan, I guess it doesn't matter if you import from Europe or US ? You also seem to have enough money In this case, I would recommend the Drexler LSD from Germany. I would say it's one of the best LSDs, and it's used by BMW Motorsport cars (not the M cars, but the cars that compete in races for BMW). I do have it and it's great.

By the way, as far as I know, the Alpina B3 GT3 (based on the 335i coupe automatic), which recently beat the BMW M3 GTS (450hp) at the track, uses KW V3 suspension (maybe specially tuned) and Drexler LSD.

As far as the suspension, I would recommend going with the KW ClubSport suspension with camber plates. Even if it's a twin-tube suspension (as opposed to the monotubes which are supposedly better) the KW has such a good track record that they must be doing something better than some others. Or at least get the adjustable camber plates from them. You are losing alot of front end grip in corners over the M3 if you are not using camber plates.

[jippii ensio]

What's your camber currently? The more camber, the quicker times.

KW V3 is progressive spring set-up, i.e. not really track oriented. HP Autowerks has upgraded many kw V3s into various other setups that are more track oriented.

[tres]

power means nothing without control

Originally Posted by DefactoM6

Hmm...well I guess you took out a fair amount of the things I would've adressed on the table. That being the case, yes obviously you need an LSD, that said, IMHO, the advantage an OS Giken would provide over a Wavetrac or a Quaife is probably questionable, given the number of successful race teams who have used Quaife ATB units just like the ones available for your car(can't speak about Wavetrac, but it's essentially the same thing). If you really wanted a clutch-type LSD, you could also have Diffsonline build you one to your exact specifications. FWIW, Diffsonline builds the diffs for BMW Motorsport's M3 GT2s in ALMS, as well as Turner Motorsports' Grand Am M3s. Personally, that's the route I'd go. You can deal with Diffsonline directly, or get them through Turner; I'd do the former.

That said, I'd look to other variables causing you to be 3.8 seconds off the pace of a stock power M3 on identical tires and te37s. IDK, something just sounds off. I could believe an LSD shaving 1-1.5 seconds a lap on a 2 minute lap time, maybe closer to the 1.5 because of the power you have, but being 4 seconds/lap slower than a stock power M3 with a similar if not inferior suspension, equal tires, same weight (if not heavier)...with the same, competent driver behind the wheel...it's just not making sense.

[Sered]

Originally Posted by tres

power means nothing without control

control means nothing without power

This make-a-cliche' game is fun

[DefactoM6]

Originally Posted by tres

power means nothing without control

I agree, it's why I'm curious about what his alignment specs are, and what his tires were (before). I can't speak for you (even though we have near-identical suspension setups), but I would imagine that you would have confidence that your car would be significantly quicker than a stock M3 around a track for a hot lap (though IDK what you have for brakes, mine would be totally cooked after a lap or two), and we don't have the power he does.

[cstavaru]

Originally Posted by DefactoM6

I agree, it's why I'm curious about what his alignment specs are, and what his tires were (before). I can't speak for you (even though we have near-identical suspension setups), but I would imagine that you would have confidence that your car would be significantly quicker than a stock M3 around a track for a hot lap (though IDK what you have for brakes, mine would be totally cooked after a lap or two), and we don't have the power he does.

As far as I know, Dinan Stage 3 with all of the Dinan suspension mods (and they have a lot !) wasn't able to outclass an M3 around the track, so this is saying something:

[JamesM3M5]

1) Drexler LSD is the best, bar none. Expensive, but will give you the best rear grip and fastest laps. Do not get a Quaife or Wavetrac. They are not nearly as good in any aspect for a rear wheel drive car. The Drexler is more tunable than any other diff for more dynamic accel and decel lockup. In the USA, we have Dan at Diffsonline that builds the fastest road-race E9x diffs in the country, but I don't know whether he can ship to Taiwan.

2) Big front bar - BIG. Small rear bar.

3) -4.0 camber front, +8 to +10 degrees caster - as much as you can get

4) -2.2 camber in the rear.

5) Total front toe -0.20 to -0.40 degrees (or 1.0 to 2.0mm per wheel toe OUT), total rear toe +0.20 to +0.40 degrees (or +1.0 to +2.0mm per wheel toe IN)

6) As little rake as possible, 5-10mm difference between the front and rear jack points on the rocker. The lower the rear is, the better. If the front is too low, grip suffers dramatically.

7) As much rear weight as you can bear - weight distribution should be at worst 50/50 front/rear, best would be 52 to 53% rear with a full tank of fuel. I guarantee that you can turn faster laps with an extra 100lbs in the trunk, provided you get on the power as early as possible.

[Javier]

first world problems

[Sered]

Originally Posted by Javier

first world problems

YOLO?

[DefactoM6]

Originally Posted by JamesM3M5

1) Drexler LSD is the best, bar none. Expensive, but will give you the best rear grip and fastest laps. Do not get a Quaife or Wavetrac. They are not nearly as good in any aspect for a rear wheel drive car. The Drexler is more tunable than any other diff for more dynamic accel and decel lockup. In the USA, we have Dan at Diffsonline that builds the fastest road-race E9x diffs in the country, but I don't know whether he can ship to Taiwan.

2) Big front bar - BIG. Small rear bar.

3) -4.0 camber front, +8 to +10 degrees caster - as much as you can get

4) -2.2 camber in the rear.

5) Total front toe -0.20 to -0.40 degrees (or 1.0 to 2.0mm per wheel toe OUT), total rear toe +0.20 to +0.40 degrees (or +1.0 to +2.0mm per wheel toe IN)

6) As little rake as possible, 5-10mm difference between the front and rear jack points on the rocker. The lower the rear is, the better. If the front is too low, grip suffers dramatically.

7) As much rear weight as you can bear - weight distribution should be at worst 50/50 front/rear, best would be 52 to 53% rear with a full tank of fuel. I guarantee that you can turn faster laps with an extra 100lbs in the trunk, provided you get on the power as early as possible.

Listen to James. He knows what he's talking about.

[cocoturkey]

Originally Posted by JamesM3M5

1) Drexler LSD is the best, bar none. Expensive, but will give you the best rear grip and fastest laps. Do not get a Quaife or Wavetrac. They are not nearly as good in any aspect for a rear wheel drive car. The Drexler is more tunable than any other diff for more dynamic accel and decel lockup. In the USA, we have Dan at Diffsonline that builds the fastest road-race E9x diffs in the country, but I don't know whether he can ship to Taiwan.

2) Big front bar - BIG. Small rear bar.

3) -4.0 camber front, +8 to +10 degrees caster - as much as you can get

4) -2.2 camber in the rear.

5) Total front toe -0.20 to -0.40 degrees (or 1.0 to 2.0mm per wheel toe OUT), total rear toe +0.20 to +0.40 degrees (or +1.0 to +2.0mm per wheel toe IN)

6) As little rake as possible, 5-10mm difference between the front and rear jack points on the rocker. The lower the rear is, the better. If the front is too low, grip suffers dramatically.

7) As much rear weight as you can bear - weight distribution should be at worst 50/50 front/rear, best would be 52 to 53% rear with a full tank of fuel. I guarantee that you can turn faster laps with an extra 100lbs in the trunk, provided you get on the power as early as possible.

James, Thank you very much for taking the time to give me a great lesson.

My current setup is shown as following:
Front: -3.10 camber with 10 degrees of toe in
Rear: -1.00 camber with 0 degree of toe

Since I only have kw v3 suspension system, I wasn't able to do much with camber so I replace my original guide support with e46 (or e36... i don't remember) M3 guid support, and I swap the left guide support with right guide support to make -3.1 camber. Otherwise the largest camber I could get with original e92 guide support was only -2.1 camber. I guess that changed the caster a little bit too.

I don't know about my caster settings. I don't know much about the effects of different caster settings... would you mind to tell me the significance and characteristics of caster settings?

I am planing on doing widebody to my car with 40mm wider on each side. I was hoping I could get 18" 10.5J square setup with TE37 SL with hoosier R6. Do you think it's a smart move? What is the best choice for front and rear tires specs you would recommend?

I have a race event coming in about 3 weeks. I don't know if I have enough time to order LSD from Drexler or Diffsonline. If not, I will probably go with OS Giken... do you think OS Giken Super lock or TCD is good enough?


sorry that I had to ask so many questions at once... We just had our 1st FIA Grade 2 track opened up a year ago. Before that, we didn't even have a nice international level tracking field here in Taiwan. The knowledge about tracking is so limited here. I really hope I could learn a thing or two here. Thank you very much for your help. I really appreciate it.

[cocoturkey]

Originally Posted by cstavaru

First, I think that if you want the best track times, you should forget the gear-type LSDs and go with a clutch-type LSD. No one (with rear traction) is using gear-type LSDs in professional races.

This leaves you very few options.

If you are in Taiwan, I guess it doesn't matter if you import from Europe or US ? You also seem to have enough money In this case, I would recommend the Drexler LSD from Germany. I would say it's one of the best LSDs, and it's used by BMW Motorsport cars (not the M cars, but the cars that compete in races for BMW). I do have it and it's great.

By the way, as far as I know, the Alpina B3 GT3 (based on the 335i coupe automatic), which recently beat the BMW M3 GTS (450hp) at the track, uses KW V3 suspension (maybe specially tuned) and Drexler LSD.

As far as the suspension, I would recommend going with the KW ClubSport suspension with camber plates. Even if it's a twin-tube suspension (as opposed to the monotubes which are supposedly better) the KW has such a good track record that they must be doing something better than some others. Or at least get the adjustable camber plates from them. You are losing alot of front end grip in corners over the M3 if you are not using camber plates.

Thank you so much for the information. I will look into Drexler LSD and see what they have to offer.

[cocoturkey]

Originally Posted by DefactoM6

What are your specs? You're welcome to PM them if you don't wish to add confusion to the thread, because I'd definitely be interested in seeing what they are. I agree, the choice is difficult. If it's any vote (though it might add to the confusion), I have 2x Diffsonline diffs for my M6 (Primary: 4.10 motorsport gears, 4 clutch, 30/90 variable ramp, REM polished (same or better than an OS Giken) and a 3.64, 2 clutch, 40% lock for long distances), and a Wavetrac in my e92. I'm happy with all of them. That said, there are definitely fewer compromises with the Wavetrac, IMO. For example, I never notice it in a parking lot. Ironically, I'm more likely to end up on the track with my e92, and I still went Wavetrac. Again, this is all for what it's worth. Everyone's going to have a different opinion on the matter.

I have written down my alignment specs in the previous post. Please take a look at them and see if you find something interesting or suspicious.

[MDORPHN]

Originally Posted by cocoturkey

My current setup is shown as following:
Front: -3.10 camber with 10 degrees of toe in
Rear: -1.00 camber with 0 degree of toe

That's a very odd alignment, especially for a track car.

You want 0 toe or just a bit of toe OUT in front and you definitely want some toe-in in the rear.

Go with James' suggestions.

Neil

[tres]

I think its all about balance the right amount of horsepower with the right suspension tuning. And of course the driver and his concentration endurance level. caz sometimes when you get your braking ref points down, your tires and brakes start wearing and your ref points is thrown off a little. Thats when your concentration comes into play.

Originally Posted by DefactoM6

I agree, it's why I'm curious about what his alignment specs are, and what his tires were (before). I can't speak for you (even though we have near-identical suspension setups), but I would imagine that you would have confidence that your car would be significantly quicker than a stock M3 around a track for a hot lap (though IDK what you have for brakes, mine would be totally cooked after a lap or two), and we don't have the power he does.

[DefactoM6]

Originally Posted by MDORPHN

That's a very odd alignment, especially for a track car.

You want 0 toe or just a bit of toe OUT in front and you definitely want some toe-in in the rear.

Go with James' suggestions.

Neil

+1000. I hope the 10 degrees of toe in on the front was a typo, otherwise your car must drive itself with you fighting for dear life, lol. Even 1.0 would be scary. For your application, I'd start with 0 toe in the front, maybe slight toe out; any more than 0.1-0.2 deg out will probably make the car feel darty and unpredictable to you. And as for the rear, on a multilink rear, you definitely want some slight toe in, because 0 toe at rest in the rear will become positive toe on acceleration, which will make the rear wheels steer themselves. I tend to like starting with lower toe in on the rear and working up to the bare minimum I need to make sure that I'm not all over the place, so I'd start at 0.1 toe in and work up from there as needed.

Camber also seems a bit wild...I'd have the rear at least at -2.0 for that front camber you're running.

Bottom line, if the specs you ran are as you typed them...I actually wouldn't be shocked if you picked up a significant amount of speed just by doing a proper alignment. If you don't already have them, I'd get some adjustable rear toe arms, upper links and guide rods, as it'll make dialing things in much easier. Definitely get an LSD; whether it's Drexler, Diffsonline, or OS Giken, all are great and will be a significant improvement, and I'm sure that any one of them can be arranged to be ready in time for your event. If you do a 255 square setup (it's possible, Dinan has done it, I believe the specs are for a 9" front wheel at et47), you should be turning significantly better times than before. If it were my car, I'd put my money into that kinda stuff, plus things like revalving/respringing your KWs (or better yet, selling them and going with a proper damper setup like a JRZ RS1, Moton, Ohlins, etc), playing with different bars, bushings/bearings, etc than dropping money on a widebody kit.



And FWIW, the Lumma design bodykit is that...a bodykit; if you want to do body stuff to lower your lap times, and you're really serious about kicking ass (and it seems like you are), then I'd look into building proper aero...a proper front splitter/undertray/canards, side pods, proper rear diffuser (don't be fooled by the descriptions around the forums, nobody sells a bolt on diffuser for this platform), and a wing done properly.

[cstavaru]

Originally Posted by cocoturkey

I am planing on doing widebody to my car with 40mm wider on each side. I was hoping I could get 18" 10.5J square setup with TE37 SL with hoosier R6. Do you think it's a smart move? What is the best choice for front and rear tires specs you would recommend?

I think that you would have so many seconds to gain with proper tires, a LSD and proper track-focused alignment.
A widebody kit would not even do anything for you, maybe hurt your aerodynamics because of lack of proper wind tunnel R&D from the manufacturer.

You can already put 255 tires in the front (or at least 245 - I have them with no rubbing on 18x8.5ET35 wheels and I could easily put a 255 with no problems but I have a sedan)...

[enrita]

put the same car with different LSD on a track and let a racing driver test it. maybe they can feel a very tiny difference but seriously a hobby driver wont have a clue.

[rismo]

Tyres, supsension - JRZ for example, linear ones and you will not regret a LSD of Drexler.

[rismo]

Originally Posted by enrita

put the same car with different LSD on a track and let a racing driver test it. maybe they can feel a very tiny difference but seriously a hobby driver wont have a clue.

I agree, but not completly, Drexler let me drove with a street adjusted setup and a track config.
This was absolutly noticable during cornering. Only the fact that the Drexler can be adjusted migth be a pro compared to other types.
But again or street use, you will have your LSD set anyway conservative to not ´burn´ it down to quick....

[JamesM3M5]

You can absolutely tell the difference between a Quaife and standard Salisbury style limited slip (such as a Drexler) once you try to put power down coming off a turn.

[cleex024]

well whats the difference between drexler and os giken? the logic seems the same except more clutch plates with osg. I have the super lock and feels great with no noise whatsoever and locks up great...but i swear on a straight line i feel like the helical lsds would do better as i feel like it would slide out less.

even with the osg seems like the car doesnt track completely straight when im on it. i am running about 370 whp and only time i lose traction is in first but it does slightly slide out to the right. either way the lsd has transformed the car and i love it. got it from vac and their finned race diff cover which i would probably say go with the shorter version if the car is a dd.

if i had to do it over id probably still go with the os giken over drexler, wavetrac and quaife mainly because i get full lock and os giken has only replaced 1 clutch pack since they opened on customer cars. they almost guarantee that it will last the life of your car so they have a great record and you dont have to replace the fluids too often. however you do have to use their fluids and its $50 a liter and takes 2 liters.

the full pumpkin cost me $3100 and vac installed it for $400 but only because i got a few different things from them all at the same time. not too bad because its less than $1000 from a quaife fully installed.