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Nasty "Clunk" from rear of car on Acceleration

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  • Nasty "Clunk" from rear of car on Acceleration

    Hi All, I just finished posting on the new member section and thought I'd get started with my first question to you all. Just quickly, for those who may not have read my intro I live in Victoria BC and got last week a '92 Caterham Super 7 with 19,000K using the Kent 1700cc cross flow motor. This car has a solid rear axle with drum brakes.

    My problem is (and I knew about it when I bought it) when I accelerate from a stop I hear a rather loud, hard "Clunk" somewhere in the back end (solid rear end, not IRS). As best I can tell (but who knows) the clunk is coming from the RR area. FYI, I have restored from the ground up many older English classic cars, so I'm fairly good with a wrench. But before I take stuff apart on this car to investigate I thought it best to ask you all your thoughts and advice.

    Are there any known issues with this?
    Is the end of the axles from the diff to hub splined each end or is there "U" joints in the hub?
    What donor car did the whole rear end assembly come from so I can source parts?
    Is the diff (crown and pinion) pre-stressed I think it is called or can it be bolted in and out with ease?
    Any tests I can preform to figure it out before pulling stuff apart?

    Any good web links you know of that cross references parts of this to to others? Or any good links for this car at all?

    Sorry for all the questions.... Pat

  • #2

    Check out Blatchat the forum for the Lotus Club of Great Britain. Much more history and many more technical posts than on our small site. Someone here may know the answer but if it's happened to others in the UK you'll find it on Blatchat.



    • #3
      Welcome. :)
      As Doug suggested, I went to Blatchat, clicked on "Search", "Tech Talk", and "from the beginning", entering the terms "live axle clunk". This yielded 26 results.
      If you are not a member there, you cannot post on Blatchat, but you can search and read, as well as PM any user by clicking on their user name.
      | | Sean


      • #4
        Rear prop shaft U joint maybe? Slide underneath the car and give it a wiggle.
        A day you don't go a hundred is a day wasted


        • #5
          Change your A-frame bushing. They do not last long - especially being exposed to heat and diff oil.

          If you still have the clunk - report back, but this should be the first thing you check on a live-axle car with a clunk.


          • #6
            Good point on the "A" frame bushing, but being a newbie to these cars I have no idea what to order, what car the "A" frames are from and or where to order Caterham (if specific) parts. Can you advise please? Thanks, pat


            • #7
              I'm not aware of a cross source for the A frame bushing. You should be able to contact anyone who sells caterham/lotus parts.

              Here are a few places to try (no affiliation)

              Dave Bean Engineering -(209) 754-5802
              JAE -805 967-5767
              Kampena - 415-341-3822
              Sevens and Elans - 978-772-3777


              • #8
                The best source is Caterham itself in the UK. They have a good online parts catalog and you can do it all by email.

                If you don't have the build manual for your car see if you can find it online someplace. There is one you can download from this website under the resources page but it's for the DeDion cars.

                Perhaps another member will have one he can copy for you.

                There is also a Caterham USA dealer in Irvine.



                • #9
                  same thing happen to my 98 live axle last month and it was the left side A arm link that was loose, we just tighten it up and changed the center bushing from the A arm (eaten by the rear dif leak), cost about $10 and the problem was fixed.
                  Good luck


                  • #10
                    I'd like to clarify what the "A" arm is. On my IRS cars the "A" arms are the upper and lower "A" arms, that hold the susp to the upper and lower mounting points. As I have a solid rear axle, I don't have what I would refer to as "A" arms. Now, there is a "V" arm that bolts on to the bottom of the diff pot and angles outwards (each side) forward. Is THIS what you refer to as the "A" arms?

                    Also, I jacked the car up and there is no slop in these joins, suggesting the bushing. Could I expect slop or not (I'm guessing not except for when under power which is a lot stronger than me!).

                    Thanks, Pat


                    • #11
                      The A frame is what you have referred to as the "v arm," yes.

                      I've never really tried to feel for slop underneath the car. When the A frame wears out, sometimes you can feel it by pulling and pushing side to side on the rear bodywork (or rollbar) of the car (getting a pendulum affect going) while the car sits on the ground.
                      Last edited by GWise; June 16, 2014, 12:59 PM. Reason: clarification


                      • #12
                        I just got a couple of "A" frame bushings from the Caterham online store. Not very expensive about $10 for the pair and about the same to mail to you,depending on where you are of course.


                        • #13
                          JAE in Goleta usually has the bushings in stock. That's where I get mine. They're cheap and it's one day shipping via UPS here in SoCal.

                          '62 Lotus Seven
                          '84 Turbo Esprit (x2)
                          '14 Evora
                          '77 Esprit S1 (RIP) :(

                          "A man must keep a little back shop where he can be himself without reserve. In solitude alone can he know true freedom." -Michel De Montaigne 1588


                          • #14
                            These are Y16 half bushes that are available from the sources listed above. The last pair I bought were from Caterham USA. No need to go to the UK for these.
                            I'll never have to buy another set as I have converted over to a spherical bearing. Best improvement ever on a Lotus for locating the rear axle (in conjunction with a strengthened axle housing).