Announcement

Collapse
No announcement yet.

Front suspension mod

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Front suspension mod

    Has anyone either managed or considered replacing the front torsion bar and Herald damper setup with a coil over. If it is possible or has been unsuccesfully tried can anyone offer advice i.e. spring rate, open / closed length etc.... OR why it did not work. Many thanx
    Jon
    Mk2 SWB Marina Roadster with a 1800 Fiat Twin Cam engine and 5 speed Abarth gearbox built in 1987
    - I have no idea what I am talking about........ but my advice is always free! -

  • #2
    Re: Front suspension mod

    Jon,
    I'm sure that I have seen this done.If my memory is correct the torsion bar was cut away just aft of the bottom arm inboard pivot thereby keeping most of the original setup but minus the tosion arm.A coil over was then placed in the same location as the original damper.Afraid that I'm not aware of spring rates etc.I also have a feeling that it had a Fiat or Alfa twin cam unit.Will dig thro' old files etc. to see if I've any further info

    Comment


    • #3
      Re: Front suspension mod

      Hi again Jon,
      Further research has provided the following info:
      A chap called Paul Hasling converted his Fiat twin cam engined roadster to coil overs primarily to overcome the exhaust system clashing with the torsion bars.He used Westfield adjustable units produced by Spax.Rear axle was also from Fiat 132,the spring mounting pads apparantly matching the position of those on the marina axle.Hope that's of some help!!

      Comment


      • #4
        Re: Front suspension mod

        Intriguing...do you know if any additional bracing was added anywhere? It seems to me that the torsion bar provides a degree of restraint to prevent the lower arm potentially pivoting about it's single bolt...wouldn't removal put undue strain on the tie-bars and generate what might loosely be described as "variable geometry"...? A pukka lower wishbone would seem to be a safer option IMHO...mind you, I'm not a suspension designer so would be interested in any other views..!
        Marlin Roadster, LWB...1860 B Series + Ford Type 9
        Renault Espace 54mm front calipers, vented discs, cycle wings and adjustable tie-bars.

        Comment


        • #5
          Re: Front suspension mod

          Hi Jez, Im still sharpening my H2 but I think Jim Jacksons car had a home brew front susp. The Triumph front end on the chassis is different right back to the scuttle.Unlike the Marina chassis it lays flat ie parallel to the ground. With a bit of luck I will finish the drawings in time for the next mag.
          Ben Caswell probably not the last word on anything here!!

          Comment


          • #6
            Re: Front suspension mod

            Jez,
            Regretably I don't have a lot of details,most of my info is from seeing the vehicle only on one occasion and a few notes i've kept.You raise an interesting point about additional bracing but again from memory i think Paul linked the top end of each coilover with a transverse bar which also doubled as a headlamp bar.I'm no suspension engineer either[ex RAF Airframes] so as such don't feel qualified to comment on the integrity of the setup.According to my notes I saw this roadster back in 1996 so without photo's and only a few scribbled notes you'll have to bear with me on any further input.Hopefully the car still exists and someone else can fill in the finer points.

            Comment


            • #7
              Re: Front suspension mod

              Jez,
              You are correct that the torsion bar adds additional "stability" to the lower susp arm. However this is probably fairly negligable. What you must remember is that ALL suspension design is compromised for road cars. Unfortunately we do not like to hear / feel every bump and pot hole whilst driving our expensive exec saloons. Therefore much effort / cost is put into designing out this NVH (noise, vibration, harshness) whilst keeping a rewarding driving experience. If the world really was flat (perfectly) then we would all drive cars that were designed like race cars. Every joint would be a spherical bearing / rod end and the geometry would be set for neutral handling with progressive oversteer characteristics and there would be no geometry movement in the suspension design at all. However on our roads as they are today you would need to have the bearings replaced every 2000 miles and most of the nuts and bolts tightened as well as your internal organs repositioned. This is one of the reasons cars use subframes. The suspension can be mounted more rigidly whilst the frame mounting bushes absorb the noise etc...thus making for a more pleasant ride.
              Car design is all about compromise. Cost to build, cost to own and now cost to dispose of. If you read one of the many books available on suspension design, they all tell you that there is no "perfect" design, just compromise. Just remember the next time you pick up that polybush catalogue, it might make your car feel more taught but it will increase the NVH value.
              Lesson over.
              Mk2 SWB Marina Roadster with a 1800 Fiat Twin Cam engine and 5 speed Abarth gearbox built in 1987
              - I have no idea what I am talking about........ but my advice is always free! -

              Comment


              • #8
                Re: Front suspension mod

                Message originally posted by: tom
                heres a very late reply!!!! my marina based marlin has front coilovers - torsions cut short and mounted in bearings can supply pics if rqd

                Comment


                • #9
                  Re: Front suspension mod

                  Hi Tom,
                  Pics would be great. I am still contemplating what to do here for the best results. You can either post them here for all to see or email them to me at jon.cox(at)blueyonder.co.uk
                  Mk2 SWB Marina Roadster with a 1800 Fiat Twin Cam engine and 5 speed Abarth gearbox built in 1987
                  - I have no idea what I am talking about........ but my advice is always free! -

                  Comment


                  • #10
                    Re: Front suspension mod

                    Tom, I'll second Jon's request for pictures, plus some comments on before/after ride quality if possible..!
                    jezcox<at>tesco.net.
                    Marlin Roadster, LWB...1860 B Series + Ford Type 9
                    Renault Espace 54mm front calipers, vented discs, cycle wings and adjustable tie-bars.

                    Comment

                    Working...
                    X