Big LSD Shootout... OS Giken, Drexler, Titan, GKN, ZF...

[driftflo]

Originally Posted by driftflo

today i built a new prototype lsd for my E46 M3 racer:
http://www.m3racing.de/e46umbau.html#20

nearly all parts are custom made or modified to my specs.

would also fit in a E92 of course... and i possibly will build another one for it, if it will handle like i expect it to! ;-)

yesterday i went racing with the above diff. i liked it pretty much in combination with sticky michelin slicks and on dry tarmac.

the first rollout was with pretty worn out michelin cup tires a few weeks ago and i had to much lockup for the little grip they provided. so as i thought, this is too much lockup for a high performing allround lsd but it is perfect for racing with slicks!

there was also some doubt about my racing experience (and if i can judge about what lsd setup a racecar needs) as i operate a drift-school and drift a lot myself. indeed i do not earn money with racing (unfortunately *g*) but i like it a lot and do it in my leisure time.
so i think i can judge a lsd not only for its sideways abilities but also concerning racetrack performance.

here is the video from yesterday racing at hockenheimring f1 track:


car is on kw competition 3a coilovers, (used) michelin slicks, stock engine, stock gearbox, i=4.10 final drive, 65% lsd with 6 clutchpacks...

here is the whole conversion documentation:
http://www.m3racing.de/e46umbau.html

[Leglessracing]

Hi there,
Have you tried the Quaife diffs at all?
Also I'm running a m3 DCT as a track/race/time attack car. Have you had any experience with putting the 4.1 diff in a dct car?

[driftflo]

i have tried torsens in other cars. better than open but not good enough for racing and high performance usage. if you want the highest performance you will need to use a clutch type unit.
and if you choose a torsen, i would prefer the wavetrac over the quaife units.

4.1 would be very short for a dct car. i built some 3.62 final drives for these cars and the customers are pretty happy with it.

[Leglessracing]

Ok great, which is the best clutch type diff that you have experience with for high performance if Torsen is not the best? I was asking motorsport24 what they use but they never got back to me! I'm in the UK which makes their parts easier to get.
I was thinking of a 3.62 but heard that some of the Team Schrimer cars were using the 4.1 diff? Do you have any issues using the 3.62 diff on a Dct car?

[driftflo]

if you read the thread you will see that there is no "best" brand, the setup is the key!
i can set you up a drexler, titan or my own zf-based unit in a way it will fit your needs. it depends on the amount of money you want so spend. if you want a drexler core it is more expensive then if i use a zf core. setup and internal parts can be done identical.

i do also send parts to the uk, that would be no problem.

i never heard of a dct car driving a 4.1 final drive. i guess the schirmer car is a 6mt... then 4.1 makes sense!
if you switch a dct to 3.62 (or any other ratio), you should have the dct software reprogrammed that you will have smooth shifts in auto mode. if you drive in manual only or dont mind a little harsher gearchanges no programming is required. i have a programmer here in germany who has the software for the 3.62.

the dct cars with my 3.62 lsd units run flawlessly! i just got an email from one of them a few days ago that he still loves this mod a lot.

[Leglessracing]

Ok great. Thanks for the info! What are your prices? Feel free to pm me if it's easier for you. It will be going in a race car build so a good setup is what I need!
My car will be getting the software reprogrammed once done and there is the possibility of a motec ecu going in the car too so reprogramming will not be a problem.

[driftflo]

pn is out...

[mef]

Hi all,

This thread is of great Interest to me and has got me thinking!

I have an E87 1 series asphalt rally car which has the E90 M3 stock diff on 3.85 ratio. The engine is an E36 S50b30 3 litre producing around 300bhp and I have a Tractive 6 speed sequential gearbox which has drop gears to make the overall final drive into 4.6:1

I have been using the car now for over 3 years on mainly UK asphalt rallies plus a couple of Belgian events too.

The car is generally very good but one thing that I have suffered with from day one is severe understeer which I have so far been unable to dial out. I've tried all sorts of front and rear spring rates and anti roll bar combinations to no avail and I recently realised that the diff is the only item that I've never changed or thought about. I have had experience in the past of fitting an over tight lsd that caused considerable understeer in a rwd lightweight kit car so I was wondering if it could be the M3 gkn diff that could be the source of my problem?

I have a spare lsd unit so today I conducted a test and found that the lsd has a considerable static preload, it seems to require quite a lot of force to break the drive between the shafts.

So maybe this is the problem, the diff is very tight and will only get tighter once the differential wheel speed is sensed. Also my car, although heavy at 1250kgs is probably a lot lighter, especially at the rear end than the roadgoing M3 that the diff was designed for.

So I am possibly looking at fitting something like an E39 M5 LSD which I understand is a conventional plate LSD like a ZF or maybe a modified version, what do you think?

Any comments or suggestions would be greatly appreciated!

Cheers

Martin

[mef]

You say you can supply a pre-built LSD core like yours which sounds perfect for me, is this from stock, how much do you charge and how soon could you get this to me in England? send me a PM if you like, I am serious about doing something very quickly to get rid of the GKN viscolok unit for my rally car.

Thanks,

Martin

[driftflo]

hey martin,

i am not sure if the understeering really comes from the viscolok. it has some preload indeed, but not that much that this will lead to massive understeer. the dynamic lockup is generated slowly, so when you hit the gas after the apex you should have no traction for the first moments but not understeering! under braking the unit is open (except preload).

anyway, for a race/rallycar i would strongly recommend a clutch type lsd! so if you swap the unit you can check if the understeering is gone. if it is still there, you definitely have to search outside the differential.

i will send you an email with some options for pre-built LSD cores that will fit your needs.

[mef]

Thanks, the understeer comes when I am trying to get on the power on a sweeping hairpin bend, like of the race track at Anglesey where there are 3 of these similar bends, the car turns in but as soon as I'm on the power it just pushes out. I have to back off or go down a gear to get it into oversteer which is not fast. The car in front accelerates around the corner and gets away! We noticed that the preload in the GKN was quite high, ie a 1m long bar with quite a lot of effort to turn the side flange.

I am very keen to replace the GKN unit with a modified ZF type, Im not sure which is the best and least expensive choice, either buy your LSD unit outright or purchase an old M5 E39 complete diff for £500 and rebuild the LSD with new and extra plates, maybe that would cost just as much so not worth it?

Charles Schmid in Belgium says that the OS Giken is perfect, Patrick Snijers often drives his 1 series rally car with good success! He's not sure which spec, S or X. This is the car seen in the second video clip near the start of this thread, 1st page!

Please send me the prices,

Cheers,

Martin

[mef]

I made a decision and decided to go with the "Driftflo" ZF type conversion! its on order.

Martin

[italyix]

Originally Posted by mef

I made a decision and decided to go with the "Driftflo" ZF type conversion! its on order.

Martin

Going to pull the trigger soon on this as well!!! Please post pics when you get urs.

[mef]

There was a bit of a delay caused by the money transfer and the bank (wrong details) but now it's on its way, will post some pics etc when here.

Martin

[mef]

Its arrived and looks the business! No time to fit it though for the Monteberg rallysprint in Belgium this coming weekend.

I'll get some pics up and get it installed in May.

Thanks "Driftflo"

Martin

[dhoggm3]

Don't know what's wrong with your OS Giken but mine locks up fast and puts the power down amazingly well. It went on the car with the VF620 SC, and it was a fabulous mod. Highly recommended.

[driftflo]

the setup was wrong! so what setup did you install?

and did you ever drive another clutch type lsd? or is this your first one ever?

[driftflo]

the funny thing about os giken lsd units is that all customers that claim they are completely happy with their units start to be silent when it comes to any questions about their setup details. tom from eas does not reply anymore, nore does dhoggm3.

as long as no one of the guys with the "working" osg units share their setup (that i can try myself then) i would not suggest this unit to anyone else!


on the other hand i received some emails where osg drivers ask me to source some spare parts for their failing axle bevel gears and spider gears.
osg says, not a single unit did fail so far?!

[italyix]

Email sent for unit inquiry.

[driftflo]

got it and just replied... thx!

[italyix]

Originally Posted by driftflo

got it and just replied... thx!

$$$ on its way

Cant wait to get it!

[italyix]

Finally US Customs released the package and this beauty showed up at my door steps Saturday.

Will be a while before I get it installed, and will post results when I do.

The unit is solid to say the least. Housing is machined and feels nice and sturdy.