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  • Roadster Rear Springs.

    I thought I would do a little research on alternative sources of rear springs as the Marina parts seem to have virtually dried up and I was looking for something a little stiffer than the very soft two leaf spring I presently have.

    It looks as if Ford Cortina Mk 1 and 2, Capri and Escort Mk 1 are all 2 inch wide and 48 inch long. I also checked the Superflex reference numbers and although the model numbers are different it looks as if dimension references are the same. A quick look at eBay confirmed that there are springs about.

    Ride heights etc would be a question of suck it and see but I thought I would offer this up in case no one else has been there.

  • #2
    Re: Roadster Rear Springs.

    One source of new or retempered springs is http://www.jones-springs.co.uk/ .

    l have not spoken to them recently myself but in pursuit of the perfect spring, they may be the people to talk to.

    What I have never found is a specific retempering service for torsion bars.

    Messing about with suspension can lead to some interesting effects and appaling handling characteristics including porpoising, which needs very little explanation.

    The loading on a Marlin Marina Roadster is very different to a Marina car or commercial. Some vehicles when fitted with commercial, larger diameter torsion bars, and standard two leaf rear springs have been recorded, swapping to standard car torsion bars helped the balance and handling enormously.
    I am pretty convinced that most of the compliant suspension comes from tyre wall deflection, Roadsters tyre pressure is nominally around 20psi to get decent handling, the front torsion bars being far too stiff. The weight distribution of the engine over the front axle is significantly different, the Standard Marina rack is bolted to the firewall behind the engine, the Marlin Roadster rack is in front on the engine. So even trying to base things on standard Marina parts is a dramatic compromise of convenience.

    I dimly remember a series of articles in Pitstop that attempted to explain the complexities, but I can't find it right now but it has been described in many interesting books.
    MOC member since 05/97
    1984 Marlin Roadster SWB.
    1800TC, Unleaded ported head, stage 2 cam. Ford Type 9 gearbox, Dolomite Sprint rear axle fitted with MGF disc brakes.
    Three core radiator, Renault Clio vented front discs.
    The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.

    Loads of Marlin Reference can be found documents here or there.

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    • #3
      Re: Roadster Rear Springs.

      Someone I met at car show recently spoke highly of The Mancunian Spring in Manchester 0161 877 1788



      I have not dealt with them personally

      Comment


      • #4
        Re: Roadster Rear Springs.

        I've had a look at both those companies and they are obviously very capable. You have to trust a company in Darlaston they don't have lightweights there !

        The Marina based Marlin is a bit of a strange brew as Steve says . My own experience is that there was originally such a mismatch in spring rates with a rock solid front end an over soft rear that it felt very odd. Actually my first drive was an exercise in survival as I had 30 psi in the tyres and the steering turned out to have several degrees of toe out with the result that in a straight line the car was determined to swap ends constantly. Subsequently I found the front suspension needed 6mm of shims on one side and 9mm on the other to achieve 1 degree of negative camber.

        Currently I have a softer front end but still an over-soft rear and after a ride in a Roadster with thicker van rear springs I feel this is my next move.

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        • #5
          Re: Roadster Rear Springs.

          Originally posted by velovol View Post
          The Marina based Marlin is a bit of a strange brew as Steve says . My own experience is that there was originally such a mismatch in spring rates with a rock solid front end an over soft rear that it felt very odd. Actually my first drive was an exercise in survival as I had 30 psi in the tyres and the steering turned out to have several degrees of toe out with the result that in a straight line the car was determined to swap ends constantly. Subsequently I found the front suspension needed 6mm of shims on one side and 9mm on the other to achieve 1 degree of negative camber.
          Intrigued...presumably you mean by packing out the lower arm eyebolt bracket..?
          If so I don't see how as surely there is sufficient length of thread to do that and fit a nut, plus the spline on the eyebolt side of the chassis bracket would not be adequately supported in the chassis rail..? Did you machine the chassis bracket at all..?
          Genuinely interested, as I'd considered using shims to even out the camber but concluded the tolerances to do so were non-existent without radical surgery.
          Marlin Roadster, LWB...1860 B Series + Ford Type 9
          Renault Espace 54mm front calipers, vented discs, cycle wings and adjustable tie-bars.

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          • #6
            Re: Roadster Rear Springs.

            There was a write up in Pitstop many moons ago whereby a member who was touring Tuscany had the misfortune to break a rear spring. The ex Ferrari mechanic in the local garage fitted springs from a Fiat Panda I believe. Apparently the handling was transformed!

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            • #7
              Re: Roadster Rear Springs.

              Originally posted by lil_red_roadster View Post
              Intrigued...presumably you mean by packing out the lower arm eyebolt bracket..?
              If so I don't see how as surely there is sufficient length of thread to do that and fit a nut, plus the spline on the eyebolt side of the chassis bracket would not be adequately supported in the chassis rail..? Did you machine the chassis bracket at all..?
              Genuinely interested, as I'd considered using shims to even out the camber but concluded the tolerances to do so were non-existent without radical surgery.
              I packed my eyebolts out from the chassis by about 3-4mm each side when I built PKK in the 80's and it improved handling.
              - 9th owner of T693 SSC possibly a factory built Ford based V8 Sportster
              - 4th owner of Q309 RNV, an early Cabrio built by Bob Copping, owned Doug & Liz Billings for 16 years
              - 9th Custodian of JRR 929D, Triumph Vitesse based special Paul Moorehouse built prior to the Triumph Roadster kits.
              - 8th owner of Roadster chassis number 2395. Now owned by Barry!
              - Builder of chassis number 2325 (PKK 989M) in the mid 80's. Now owned by Eric & Lynne.

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              • #8
                Re: Roadster Rear Springs.

                I had a Riley 1.5 (that had torsion bar front sus) and packed the inner end of the lower arm out, using large diameter washers. I was running 7 inch wide revolution wheels and was after a flatter footprint. But the short wheelbase coupled with the wide track made the car almost square.

                I guess youthful driving couple with the power and configuration of the wheels caused most off the spins!!

                Comment


                • #9
                  Re: Roadster Rear Springs.

                  Correcting the camber was something I had put off for a long time but turned out to be surprisingly easy and paid off a big dividend in terms of handling as originally I had about 1 degree positive and about 2 or 3 degrees positive on the other side.

                  Give the nuts on the eyebolts a soak with Plus Gas or WD 40 for a couple of days running as they won't have moved in a while and then undo them. If they won't move I find a bit of a jerk to tighten first loosens them followed by a big bar to undo. Lever the lower arms outwards and then cut a thin card template with a 12mm (I think) hole and slide it onto the eyebolt and mark the oval outline of the eyebolt base. I made several shims in both 1 mm and 3 mm steel drilling them first and then cutting them out with a 0.8 cutting disc in an angle grinder. There are several devices you can use for setting camber, originally I used a modified Kart pendulum set up but recently bought a Gunson bubble instrument with a magnetic base that can be conveniently attached to the brake disc.

                  Remember to jack the wheel hub to where the wheel slides onto the studs and keep fitting shims until you get to the desired setting, one degree seems to be the generally accepted best figure. A white typists correcting pen works well for marking out metal. I used a drop of Loctite Nut Lock for the final fitting of the eye bolt nut. Despite having to use 9 mm of shims on one side the eyebolt nut still fully engaged. So all in all quite easy

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                  • #10
                    Re: Roadster Rear Springs.

                    I am sure I would have remembered that car ! Actually I passed my driving test in one of those and don't remember it having very re-assuring handling even as standard.

                    Comment


                    • #11
                      Re: Roadster Rear Springs.

                      I was looking for some information on Marina specs on the internet and came across a very interesting little bit of information on Wikipedia that may explain the Marina's wandering back end.

                      Apparently one of the original floor pan features was to use a central spine as a hard point for mounting components and taking load inputs in this case the inclined shock absorbers which as well as being less efficient at this angle led to bump-steer of the rear axle, which is exactly what feel is happening. I though it strange that this happened with Marina rear suspension whereas Capri and Cortina suspension with virtually identical springs and axles but vertical shock absorbers behaved (for the period) with much better handling.

                      Maybe a change to vertical shock absorbers is a vital first step for Roadster handling ?

                      Comment


                      • #12
                        Re: Roadster Rear Springs.

                        Many people swear by Spax adjustable shocks for the rear, including me.

                        Admittedly I am a fair amount of ballast and on some local roads I could easily bottom out the rear suspension. Spax shocks improved both comfort and handling.
                        MOC member since 05/97
                        1984 Marlin Roadster SWB.
                        1800TC, Unleaded ported head, stage 2 cam. Ford Type 9 gearbox, Dolomite Sprint rear axle fitted with MGF disc brakes.
                        Three core radiator, Renault Clio vented front discs.
                        The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.

                        Loads of Marlin Reference can be found documents here or there.

                        Comment


                        • #13
                          Re: Roadster Rear Springs.

                          I always had them set on a couple of clicks up from the softest setting which improved the comfort but would not help the axle location…
                          Mk2 SWB Marina Roadster with a 2.0L Pinto built in 1986

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                          • #14
                            Re: Roadster Rear Springs.

                            I agree with Steve Green that Spax are up there with the best available shocks. However this was my Eureka Moment as I realised that the sideways push of the shocks was what I was feeling. I hadn't really appreciated that it was possible to make a solid rear axle bump steer but somehow BL achieved the impossible.

                            Once summer is over I have to seriously look at possible relocations of the rear shocks in a vertical position, I am thinking of possibly in front of the axle with weld on mounts inside of the chassis tubes.

                            Comment


                            • #15
                              Re: Roadster Rear Springs.

                              The top shock mount is off set to the mounting depending on which way they are bolted up it may be possible to improve things by turning them round to make the shocks a bit more upright.

                              If the car is bump steering from the rear I would suspect the front spring eye bush or a broken spring.

                              I tow a considerable trailer(see my Avatar) with my hybrid and have never had any trouble.
                              Ben Caswell probably not the last word on anything here!!

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