[W126 Coupe] Brake Pads

[Divov]

Yesterday I took my anti-roll bar and rear shocks through to Bilstein.
Chatting to Ted Garstang of Bilstein, I said I wasn't happy trying to overcome the over-steer characteristics by stiffening the rear shocks and felt that stiffer anti-roll bar was the right way to go. 
He said why? They were not going to alter the damping rate - only the rebound rate so the car would still squat the same under power so I wouldn't know any difference.
Interesting that he alluded to seal issues on the AMG shocks but said that wasn't a problem because they could fix them with a minor mod. He said that they were still old technology (circa 1980) and the new Bilstein's had different pistons & seals. They would strip my rear shocks and check & have a look as perhaps they already had the maximum rebound valving in which case he would see if there were any of the newer pistons which could be adapted to fit the old AMG shocks. He recons he can do it.

In reply to Mike Ramay, disconnecting the SLR seems very simple. Bilstein here did the job and what I understood is there is a load sensing gismo which gets locked by putting a 5 mm bolt through it when it is at the level position and then the fluid no longer passes through and they just disconnected the shocks and removed them and the spheres.You have to fit H & R springs as the oe springs are too soft and that's it. My cars SLR reservoir is still full and apparently it is a doodle to reconnect the SLR when I want to.

Jonathan, the revalving etc is all done by Afrishox here which is Bilstein South Africa. There must be that facility in the States surely?

On the anti-roll bar: Ted took one look at it and said only a quality car like MB make such a beautiful item. He loved the swaged on washers which prevent the bar sliding laterally in the rubber mounting bushes and the flat section that goes to the wheels. Said only Benz bother to do quality work like this! He said by replacing the rubber mount with aluminium billets will definitely have the effect of increasing the roll stiffness and said it is easy to do. All you need is 2 pairs of aluminium blocks 40 ox 135 ox 20 mm. Clamp each pair in a drill press and drill the hole at the joint of the 2 blocks so as the sandwich the bar between. A 5$ homemade mod. Merc's oe saddle bracket stays in the tool box.

  ----- Original Message ----- 
  From: Jonathan Hodgman 
  To: Mercedes Coupes Mailing Lists 
  Sent: Wednesday, April 04, 2007 1:53 AM
  Subject: Re: [W126 Coupe] Brake Pads


  I agree, if you loop a Mercedes you have some definite issues... The only way I can get them to oversteer is abrupt steering inputs and a heavy right foot.  

  I'm partial to running the same size tyres all around on my cars..with the track rubber getting the power down was never a problem.  I think the next set I'll be trying will be Yoko's AO32's..they should be even stickier then the Corsa's.  

  At the moment given that I'm not actually racing, just running about the track making 3 series (or rather their drivers) look bad..  I'll be curious to see how those machined rear mounts come together.  I'd like to find someone who could fab up polyurethane bushings for our cars...but I fear pricing will be a bit over the top. 

  My infrared thermometer gave up the ghost two days before my last track event..I hope to get another soon so I can keep a log of tyre temps etc....  

  Who is re-valving your shocks? I have a set of AMG valved Bilsteins that I need to send out re-building @ which point I plan on having them put on a shock dyno to compare to Bilstein's HD's...we shall see. 

  Good times!

  Jonathan



  On 4/3/07, Divov <divov at tiscali.co.za> wrote:
    Carroll Smith, in one of his excellent books on race car preparation, wrote that most race car drivers resist the race engineer dialling in more over-steer characteristics in to the car - and yet their lap or sector times improved. Mild over-steer is much easier to drive. Our 126's all have designed under-steer which is what makes them such safe and predictable (and pleasant) cars to drive at high speed. There are no gremlins hiding in the woodwork. My track experience on the BMW range of about 15 years ago showed the opposite. If you were not careful these cars (3, 5 & 7 series) would bite you badly. Mr average was far safer in a Merc.
    Take any big Benz since the W116 on a skid pan and it is almost impossible to induce over-steer - even on a skid pan! They are such mild and good natured beasts.
    As marvellous as mild under-steer may be for road use, it is not the quickest way around a race track in extreme driving.

    Almost in another life (22 years ago) I raced (and rallied) fairly seriously and have only just returned to play in a fairly Mickey Mouse race category. I know my weakness is race car set up. I tend to subconsciously drive around the cars deficiencies and not recognise them.
    Your points on racing on slicks are spot on correct.
    However, anyone as untalented as I am at understanding feed-back from the car has no chance on slicks because the grip is so prodigious that it masks the handling deficiencies.(and yet there was more good things to come).  I want to stay on road tyres until I feel that I have more or less got the handling well sorted.

    Reading tyre temperatures tells one a lot about what the chassis is doing. It doesn't need a brain surgeon to tell you that on a 126, the front wheels are doing a disproportionate amount of the work. You are wasting power to 'plough' the car against the under-steer characteristics.
    The question I ask myself is since our cars inherently under-steer, why are we putting wider rubber on the rear wheels? Dog logic says a wider foot print can only make it worse. The rears are already not doing their fair share of work. Is this because it looks "Sportive" or monkey see monkey do?
    As a joke, in one of the practice sessions I intend to switch them around, wider tyres to the front and take a few lap times and see what happens. 
    I will report back to this forum....

    In the mean time I am having stiffer rebound rate settings done to my rear shocks and removing the rubber mountings to the rear anti-roll bar and replacing them with drilled aluminium billets to increase rear roll stiffness. If this is still not enough I shall fit two stock anti-roll bars. That may be too much...
      ----- Original Message ----- 
      From: jflyer2 at aim.com 
      To: mbcoupes at mbcoupes.com 
      Sent: Tuesday, April 03, 2007 9:54 PM
      Subject: Re: [W126 Coupe] Brake Pads


      I recently saw several track type street tires in a catalog from The Tirerack. They look like race rubber with a few grooves. Sort of like a racing rain tire. If you're using the car for the street as well as the track, they might be something to look at. 

      Otherwise, go for race rubber. Race tires will make you feel as though the car is on rails until they break loose then its another story. With street tires you can feel when they are at the limit of adhesion. With race tires, they give almost no warning before they let go. It seems like they are either stuck like glue or driving on ice. 
       
      -----Original Message-----
      From: jhodgman at gmail.com
      To: mbcoupes at mbcoupes.com
      Sent: Mon, 2 Apr 2007 8:51 PM
      Subject: Re: [W126 Coupe] Brake Pads


      Hello Alec,
      I know how it goes...My Pirelli's came gratis from a Very kind friend of mine!!

      I would NOT run two different tyres front and rear, you will have truly evil handling..one end sliding @ one level and the other @ another. 

      Still, running a street based tyre on the track is a HUGE compromise.  I went out in a friends BMW w/ PS2's and even in the passenger seat I could feel the tread squirming.  I believe if you get a proper set of rubber you will be Very impressed as to how well your car handles. 

      Sounds like a Very interesting series!  That's something I would like to do over on my side of the pond..perhaps as I get more track time in I'll look into actual racing:) 

      Have  you removed the heater core? Blower motor?  I would think you could do some lightening of the bumper/crash supports.  

      Here is the car I was/am running:
      http://blueridgemb.com/?p=6

      You can also watch a clip of a track w/e here:
      http://www.youtube.com/watch?v=ZJyC_lugMJw

      Your 500/560 project sounds like a Lot of fun:)  Should you be interested I can also help w/ hotter cams as well as the exhaust.  Is the engine from the saloon an ECE?  I would run the VIN through the Russian Mercedes club site and check: 
      http://www.mbclub.ru/mb/vin/index.html?lng=eng

      Can you run items such as custom drive shafts (thinking carbon fiber).  Also, check the backing plate on your diff, an aluminum one is available if it's not already.  Are you allowed to remove chassis grommets?  There are Lots on these cars and I'd wager they would add up to a worthwhile amount of weight. 

      Also, feel free to contact me off list anytime:
      blueridgemb at gmail.com

      Jonathan 





      On 4/2/07, Divov <divov at tiscali.co.za> wrote: 
        I'm working on a shoe-string budget.
        I didn't choose the Bridgestone's other than they were what was lying about in the workshop!
        I am fitting (again they are lying about!) 2 half worn Dunlop SP Sport 7000D size 205/55ZR16 91W for the front for the next race on 21 April.
        They look more track suitable as they have a V groove pattern as opposed to the Bridgestone's which are block tread.
        I'm planning on leaving the Bridgestone's on the rear as they are still good. Is that an evil thing to do??
        I don't think these Bridgestone's are run flats. Maybe I'm wrong...

        The rear has quite a marked neg. camber and the fronts are at 2 degrees.
        I have taken a chance running 16" wheels instead of the standard 15". It is not actually allowed but until someone picks it up I shall continue. 
        17" are out of the question!

        You running 250KW at the wheels!  Wow - What a beast!! What have you done to get all those beans?

        By the way I am building a purpose racer and racing the 500 is only as a stop gap so as to get accepted in the class & the association. 
        They bent the rules to let me race 'on probation' as the cut off date for Historic racing is 1977.
        As they politely wrote "Your continued participation will depend to a large degree upon the acceptance of your participation by your fellow competitors and what they feel about you racing with them" In other words don't be a pig or a moving chicane or an out of control idiot. After two events the guys seem quite happy and have come to realise that this is not a joke entry and the car is very much under control and, much to their amazement, a serious competitor. The other classes (the more serious boys) watch our races and I was paid some very flattering compliments after the last race meet where they came to me and shook my hand and said they can't believe what they were seeing. My category includes the predictable assortment of Alfa's MGB's small Ford's Triumph TR6 Porsche 911's Morgan +8 AC Cobra and even a Lotus 23 BDA. So yes, the Benz is a bit of an odd ball in this company. 
        People here simply don't race a Benz so the crowds like it as it is so totally different. Benz's are supposed to be for old goats with big cheque books and fat stomachs!

        So, the master plan is as follows:
        I have another 500SEC in to which I have fitted a 560 motor & box from a smashed saloon. I got the wiring harness with all the computers etc and I now need someone to wire up the car. It still has the 500 back axle. On this car I have gone on a witch hunt to reduce weight. Class rules dictate that the interior must retain all the original trim & carpets.
        I have ditched the aircon & all its components. Removed sunroof motor, rear window motors etc, changed front seats to light weight racing seats (permitted). 
        I have to retain all the glass (no Lexan or perspex) & no fibreglass panels are permitted. I am hoping to shed 2 to 3 hundred kg's.

        I suppose I shouldn't be getting too carried away on the present car and rather get on with finishing the real race car.
        Yes, I am dead interested in the AMG headers and down pipes which I would want for the real car. Let me know what sort of numbers we are looking at.
        I would like to pick your brains on the 560 to get some real grunt and I'm spoiling to mix it with the 911's. With the 500 I can forget it. It's a dog.

        Regards
        Alec
          ----- Original Message ----- 
          From: Jonathan Hodgman 
          To: Mercedes Coupes Mailing Lists 
          Sent: Tuesday, April 03, 2007 12:04 AM
          Subject: Re: [W126 Coupe] Brake Pads


          Oh, my fronts took utter abuse, but the car isn't pushing, @ least not like it does when I over cook it on the street.  My left front tyre was all but done after the w/e, while the other three were looking OK (only 3 left hand turns).  Perhaps you might try changing out your suspension for more conventional bits?  Also, are you allowed to run larger wheels?  16's give you a little too much sidewall IMHO.  How do you have your front suspension set?  I'm running 2 degrees negative camber up front (I usually run 1on the street)...  

          I would also recommend getting rid of those Bridgestone RE71's and getting a more track oriented tyre.  >From the pictures I am seeing you have Way too many tread blocks and the tread wear is Very high for running on the track.  The only 71's I could find were of the runflat variety, if yours are the same I'd say that's one more reason to move onto a different tyre.  Runflats are not an ideal track tyre. 

          My car should be making about 250KW @ the wheels.  I am also running a 2.82 gleason style locking diff..  I never shifted below 3rd on the whole track, and only shift twice..once up to 4th on the back straight and then back down again while braking for the next turn.   

          The 220KW version is a mix of cams, pistons, displacement, computers, EHA differences etc..

          My car used to have the full AMG active suspension, but they/it was known for having issues/prone to leaks and was thus switched back to conventional suspension.  



          I noted your other post on exhaust, should you be interested I am duplicating AMG's headers for our cars as well as mandrel bent stainless down pipes.

          Or, in the next year or so I should have my TT setup sorted and available to interested parties;-) 
          Jonathan



          On 4/2/07, Divov <divov at tiscali.co.za > wrote: 
            I am amazed that you say your car doesn't understeer because these are understeering cars by design which is what makes them so safe and docile as street cars. 
            Next time you race, as you pit, jump out and feel your tyre temperatures. My front tyres were very considerably hotter than the rears which clearly shows they are working a hell of a lot harder. I felt in some corners I was 4 wheel drifting - tyres screaming like hell - but just kept the power full on as there was still enough road left and the car was stable. In the tight stuff I was definitely having understeer. Only a total of 30 - 40 miles race distance and previously 50% worn front tyres were totally trashed. Its a right hand corner circuit so left outer smooth and right side inner smooth.
            I only have 170KW compared to a Euro 560 which has 220KW so you can use your extra power to break rear traction and hang the back out.
            A difference of 50KW is massive. Where does a 560 get all this extra grunt? Surely not just from an extra 600cc?
            I had my car on a Dyno and got 150hp on the wheels which the guys said was exactly par for a 500 on their dyno. 
            Note that we are at 6000ft altitude and as a rule of thumb we are 17% down on coastal power output & no 2 dyno's read the same so it is comparing apples to bananas.

            I have considered using double stock anti-roll bars because the design of the merc anti roll bar is not as simple to fabricate as on many other cars and also I happen to have a spare AR bar. Just have to figure out a mounting arrangement which I don't think will be too difficult.
            Re: tyres used. See my previous post - Bridgestone RE 71.
            Pressures were cold. (tyres filled with Nitrogen - not air.)
            Re: Shocks - I am using the Bilstein AMG adjustable shocks. Front were set full soft and rear set full hard.
            Springs: Front are cut down stock springs and rears are H & R's replacing the self levelling suspension.
            Lowered front by a whopping 85mm (previously my car always stood particularly high in the front) & rear by about 70mm
              ----- Original Message ----- 
              From: Jonathan Hodgman 
              To: Mercedes Coupes Mailing Lists 
              Sent: Monday, April 02, 2007 6:55 PM
              Subject: Re: [W126 Coupe] Brake Pads


              Hello Alex,
              Yes, very different conditions as well! Road Atlanta is fairly long, 4.088k. My brakes were OK aside from the one hard stop from from 230 kph down to 80 or less kph.  Right before this run is the 2nd hardest braking point on the track.  Brake fluid was about 20 hours old when I went out;-)  

              To be honest, the car doesn't really understeer..  I have switched all my springs for fresh H&R's, running 2 nib in the front, 3 nib spacers in the rear.  I'm using Bilstein HD shocks all around.  The next time I go out I'm going to add spring rubbers to the shims as I'm getting a bit too much compression on the drivers side.  What tyres are you running?  I was using Pirelli P-Zero Corsa's 255/40/17's. 

              Are those tyre pressures hot or cold? I was running 2.75 bar in the front, 2.85 bar in the rear.  I found in raising the rear above that caused it to get a little loose..  

              I've have heard differing opinion on running a thicker rear anti roll bar..  Some say it will upset the handling, others say it handles much better. 

              Jonathan
              I know one fellow down in AU actually managed to double up on the rear bars, and he was thrilled w/ how the car handled.

              On 4/2/07, Divov <divov at tiscali.co.za > wrote: 
                Hi Jonathan,
                Bridgestone RE 71  205 55 VR 16 front
                                                     225 50 VR 16 rear
                tyre pressures 2.8 bar front
                                          3.2 bar rear

                Track is very short & very tight. Lap times 58 sec!
                Max speed down main straight is only 150kph then braking into a hairpin bend.
                Back straight maybe 130/135 kph braking into hairpin.
                Two other braking points.
                Brakes never have a long time to recover.....
                Very different conditions to your track.
                Lichtenburg circuit has a reputation for being hell on the brakes.

                How fresh is your brake fluid?
                I had boiling fluid until I flushed it out & put in fresh fluid.

                What have you done to counter the under steer?
                Are you still on stock rear anti roll bar?

                I think I need to make up a new one 16mm diam in place of the stock 14mm item.
                Is that going to be enough? - time will tell.

                I also melted the sensors long ago. Don't bother will them on the track.

                Alec

              -- 
              Blue Ridge Mercedes/AMG East
              Offering Enthusiast Service, Restoration and Modification.
              Providing quality parts to discriminating customers in all parts of the world. 
              Located in the Greater Atlanta area.
              http://www.blueridgemb.com
              http://www.AMGEast.com

              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)
              2006 Z4 3.0Si M spec 6sp 

------------------------------------------------------------------

              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.




          -- 
          Blue Ridge Mercedes/AMG East
          Offering Enthusiast Service, Restoration and Modification. 
          Providing quality parts to discriminating customers in all parts of the world.
          Located in the Greater Atlanta area.
          http://www.blueridgemb.com
          http://www.AMGEast.com

          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)
          2006 Z4 3.0Si M spec 6sp 

----------------------------------------------------------------------

          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.




      -- 
      Blue Ridge Mercedes/AMG East
      Offering Enthusiast Service, Restoration and Modification. 
      Providing quality parts to discriminating customers in all parts of the world.
      Located in the Greater Atlanta area.
      http://www.blueridgemb.com
      http://www.AMGEast.com

      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)
      2006 Z4 3.0Si M spec 6sp 
The MB Coupes Website!W126 SEC Mailing ListPostings remain property of MB Coupes, L.L.C.
--------------------------------------------------------------------------
      Check Out the new free AIM(R) Mail -- 2 GB of storage and industry-leading spam and email virus protection.



--------------------------------------------------------------------------


      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.




  -- 
  Blue Ridge Mercedes/AMG East
  Offering Enthusiast Service, Restoration and Modification. 
  Providing quality parts to discriminating customers in all parts of the world.
  Located in the Greater Atlanta area.
  http://www.blueridgemb.com
  http://www.AMGEast.com

  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)
  2006 Z4 3.0Si M spec 6sp 


------------------------------------------------------------------------------


  The MB Coupes Website!
  W126 SEC Mailing List
  Postings remain property of MB Coupes, L.L.C.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.pairlist.net/pipermail/mbcoupes/attachments/20070404/88fc4a8e/attachment.html>