[W126 Coupe] Help! : diff ratio's

[Divov]

Hi Jonathan,
The local used Merc spares dealer is being very kind to an old fool trying to race an SEC.
He has offered me a unit on exchange for R1000 ($145) which is 'for nothing'.
Importing would 'blow the budget'!
I raced last Saturday back at Swartkops and did a best lap @ 1min 27sec  compared to 1.31 before suspension mods.
I felt that I under-performed (excuse: I was feeling ill) and feel I should be able to do 1,25's. 
It was amusing that the Merc started on the line next to a Lotus 23 & a Porsche Turbo on the other side.
They both out-dragged me (surprise) but it is interesting that I do identical lap times. I'm quicker under braking & thro the corners.....
To be fair, both those cars are driven by total paw-paws. - it's not that I'm so good!
After the race I found that the R/F calliper was dragging quite badly and that couldn't have helped...

For the next race I have fitted the bigger (and twin pot) 560 callipers and front discs. I am going to drill the discs.
I have also switched to racing brake fluid : Ferodo Formula Racing (boiling point in excess of 300C / 572F) 
Mineral not synthetic. I have an aversion to synthetic brake fluids.
I am also switching to semi slick tyres:
Dunlop Formula R - 205/50R16 87V front
Dunlop Direzza 02G - 225/45R16 89W rear
We got a deal through the association that these semi's cost about the same as a road tyre. What a win.
I also plan to change the diff as in one place the car kept hunting between 2nd & 3rd gear exiting a tight section. 
There is a section of rumble strip after a tight corner when entering a very close by sweep and even with foot flat this caused the car to change to 3rd and, as I passed that, she kicked back down to 2nd (@ about 5500rpm) again and then back to 3rd a few moments later. With the closer ratio diff I want to be in 3rd and stop all these unnecessary gear changings.
The box seems to change at the red line (6000rpm) when left to its own devices if I'm foot flat.
The next project is to find some more power.
I have been warned against fitting locally reprofiled cams so I guess I'm going to have to invest in some imported cams.
Anyone got any experience with them?
I have looked at the stock heads and there doesn't appear to be much that porting is going to achieve. 
There is no room for bigger inlet valves but one could go a lot bigger on exhausts.
Is there any point in that? I think there is an optimal ratio of inlet to exhaust size?
So, just with a free flow exhaust, will cams achieve much??
Alec D.
  ----- Original Message ----- 
  From: Jonathan Hodgman 
  To: Mercedes Coupes Mailing Lists 
  Sent: Thursday, April 26, 2007 6:26 PM
  Subject: Re: [W126 Coupe] Help! : diff ratio's


  Hello Alec,
  The 2.65 to my knowledge is Not LSD.  However, I think the japanese spec 560's have 2.65 LSD diff's.  Also, I think you can look for some LSD R107 2.82's in europe.

  Good luck!

  Jonathan 


  On 4/26/07, Divov <divov at tiscali.co.za> wrote:
    Thanks for that!
    It looks like the 2.65 diff is the item I need to lay my hands on.
    Where did you say you parked your car at night? !!
    Regards
    Alec

    ----- Original Message -----
    From: "Dawid Loubser" < dawidl at solms.co.za>
    To: "Mercedes Coupes Mailing Lists" <mbcoupes at mbcoupes.com>
    Sent: Thursday, April 26, 2007 5:27 PM 
    Subject: Re: [W126 Coupe] Help! : diff ratio's


    > Not at all, Alec... I am way more ignorant than you, trust me.
    >
    > ASR = "Anti-Slip Regulation" a.k.a. Traction Control.
    > Electronic countermeasures to prevent wheel spin under 
    > any circumstances. The 560SEC was the first car in the world
    > with that fitted. An easy way to identify a car with that
    > fitted is just to look at the instrument cluster. There's an "ASR" 
    > warning light next to the ABS, etc, and there is a big yellow
    > warning light with an exclamation mark in the middle of the
    > speedometer that lights up whenever ASR is in action.
    >
    > D.
    >
    >
    > On 26 Apr 2007, at 3:59 nm., Divov wrote:
    >
    >> Dawid,
    >> Pardon my ignorance, what is ASR?
    >> Alec
    >> ----- Original Message ----- From: "Dawid Loubser" 
    >> <dawidl at solms.co.za>
    >> To: <satish at tummala.net>; "Mercedes Coupes Mailing Lists"
    >> < mbcoupes at mbcoupes.com>
    >> Sent: Thursday, April 26, 2007 3:31 PM
    >> Subject: Re: [W126 Coupe] Help! : diff ratio's
    >>
    >>
    >>> Hi Satish, 
    >>>
    >>> Thanks for the useful info. My 560SEC has ASR - does this
    >>> automatically
    >>> mean it has a 2.65 ratio? Or was this a model-year-difference?
    >>>
    >>> thanks, 
    >>> Dawid
    >>>
    >>> On 26 Apr 2007, at 1:28 nm., Satish Tummala wrote:
    >>>
    >>>> LSD diffs have a tag requiring special hypoid gear oil located on
    >>>> the 
    >>>> right lower corner of the rear case.
    >>>>
    >>>> Most 560SECs had 2.47 diffs with LSD standard.  Some 560s with
    >>>> ASR had
    >>>> 2.65 rear ratios. 
    >>>>
    >>>> Most 500SECs had 2.24 diffs without LSD.
    >>> The MB Coupes Website!
    >>> W126 SEC Mailing List
    >>> Postings remain property of MB Coupes, L.L.C.
    >>
    >> The MB Coupes Website!
    >> W126 SEC Mailing List
    >> Postings remain property of MB Coupes, L.L.C.
    >
    > The MB Coupes Website!
    > W126 SEC Mailing List
    > Postings remain property of MB Coupes, L.L.C.
    The MB Coupes Website!
    W126 SEC Mailing List
    Postings remain property of MB Coupes, L.L.C.




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  1996 S600 Euro "Scharnhorst"
  1991 560 SEC Full Euro ECE
  1991 560 SEC 226Hp/271ft/lbs:)
  1989 560 SEC AMG (N.Amer 250/295)
  1987 560 SEC US Spec
  1986 560 SEL AMG 6.0L 32V
  1986 560 SL  White on Burgundy
  1985 500 SEL Euro (Parts Car)
  1985 300 CD For Sale
  1980 280 SE Euro
  1978 300D TMU
  1987 560 SEL 162K Midnight Blue on Gray RIP:(
  1987 560 SEC Sold
  1992 E300D 140K Champagne on Parchment tex (Sold) 
  1990 560 SEC 154K Anthracite on Gray (Sold)
  1988 300 TE 160K Burgundy on Palomino (Sold)
  1980 280 SE US 185K (Sold)
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