Having sorted the front shocks- and made a slight improvement to the suspension noise, I decided to move on to the rears. I was also aware that corroded rear springs had appeared on the last MOT list of advisories so it was probably a good time to swap those too- although to be fair a slightly corroded spring would probably last for years!
Anyway I bought two MAPCO rear shocks 20509 with new top mounts (Sachs 802 580) as well as two Blueprint rear springs. The job is relatively simple and straightforward provided that the parts supplied are correct. Obviously you cant can't compare new to old until you have stripped the old, but you can at least make sure that the new top mounts do fit the new shocks! I failed to do this and came to regret it.
The first step is to jack up the rear- although this is strictly only necessary if you are changing the springs- you can change the shocks without raising the car!
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| I jacked using a pad under the rear spring seat |
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| ... and supported the car at the rear jacking points using axle stands with pinch seam adapter pads. |
The top mount is hidden below the trim, and removing the trim is in many ways the trickiest part of this job. Slide the back seat forward and fold the backs down.
There are two pop fastenings each side in the carpet-like lower trim- pop these out using a flat lever from beneath
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| Trim retaining pop button |
and fold the carpeted trim on the sides of the boot inwards. You will need to unclip the top vinyl trim panel (through which the seat belt passes) to move the trim out of the way.
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| Folding the boot trim inwards towards the centre of the boot- having loosened the upper vinyl C pillar trim |
... but its not necessary to free the carpet trim entirely... Which is just as well as I was baffled by these white nylon clips that attach the front edge of the boot side trim to the C pillar at the rear if the rear door. They are glued to the underside of the trim and somehow clipped onto the edge of the C pillar. I could find no way of releasing them and attempts to do so simply broke the glued bond and pulled them off the carpet trim. Luckily you don't have to release them to get at the shock absorbers. If you know how to unclip these please let me know.
White nylon clip attaching front of boot side .trim to C pillar... Here its pulled away from the trim but remained firmly clipped to the C pillar
... and the seat belt can stay through the C pillar top trim.
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| The C pillar trim can be popped off completely using a flat lever from underneath- note the yellow pop fastening- a second one has fallen out of the upper plastic bracket and will need to be replaced. Apart from these this trim piece is held by flat tabs along the opposite edge |
This exposes the top of the rear shock absorber. It would have been perfectly simple for this shock to have a regular square or hexagonal section- or possibly even an internal Torx or hex socket so that it could be easily held whilst loosening the shock top nut. For some reason it has an odd lozenge shaped 5.2mm projection that fits a special tool if you have one. If not then the recommendation is to grab it with a pair of mole grips or adjustable spanner whilst you loosen the nut beneath. It works but it lacks finesse and it can't accommodate much force! I think it would be better to use a good adjustable spanner... Or best of all buy the Nissan tool (6.2 mm size)
Remove the road wheel and support the suspension arm with a trolley jack
Working from under the car remove the shock absorber lower bolt (16mm)
Remove the top bolt completely and then remove the shock from under the car.
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| Old shock absorber removed. |
You can then lower the jack to relieve the spring pressure and push the arm downwards to remove the spring. This can be a bit awkward as its held in rubber cups top and bottom. Try to leave the lower cup in position because it has three mounting tangs and so its a little more fiddly to refit than the upper which is a simpler push fit in the body.
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| Old spring in lower cup |
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| Lever the arm down to fiddle the spring out |
In my case the lower rubber mount came out with the spring despite my efforts so I cleaned up the seat...
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| Cleaned up seat |
... and refitted it with the new spring. The new spring will only fit one way, the top end is smaller and locates in the upper rubber mount, its too small to locate in the lower.
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| New Blueprint spring in position. |
New shocks- MAPCO 20509
The new shocks come with dust covers, top mounting rubbers and spacer. Do not forget to prime them by pumping them through their full stroke 3-5 times in an upright and vertical position before fitting.
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| The top mounts supplied with the new shocks- mistakenly I had assumed that these were intended for use! |
Here things went wrong! Check that the top mounts supplied are actually suitable for your car. I opted to use those that came with the shocks but these would not tighten up on the car body- a fact I didn't discover until everything had been refitted and the car back on its wheels!
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| Strut fitted using the top mounts supplied with the shocks |
Before tightening, refit the wheel and lower the car.
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| Top mount tightened down- the shocks could still slip around! |
To cut a long story short the mounts that came with the shocks are not suitable for the Micra- they will not locate positively in the holes in the body intended for them, or at least not at the levels if torque I was able to exert using mole grips to hold the strut. You need the correct top mounts for the Micra- and for the K12 at least these are the Sachs 802 580; they are shaped to fit closely into the hole in the body. However even this wasn't a solution immediately because although these top mounts were a perfect fit in the car body (and indeed onto the old shocks) - they simply would not fit the new shocks. Investigation showed that the old Nissan shocks have a 9mm shaft, and both old and new Sachs top mounts have a 9 mm bore. The Monroe dampers have a 10mm shaft and come with mounts that also have a 10mm bore. At present I'm not sure if I ordered the wrong shocks or whether the new ones have simply been made to a different (wrong) spec, I am awaiting confirmation on that. I am however now unable to return the shocks because their strut ends became damaged in my unsuccessful attempts to tighten the rubber onto the body (remember the unsatisfactory arrangement necessitating the use of mole grips- this is not suitable for any significant force). Consequently, I am hoping that different top mounts are available made to fit both the Micra and the new shocks! I would prefer to swap the tops which is much cheaper than buying new shocks. If these are not available then I will have to try and ream out the top mounts I do have until they fit.
At this point then I had to abandon the installation and refit the old shock absorbers. This is how I know that you can swap the rear shocks without raising the car- as having refitted the wheels and lowered it, I was loathe to lift it and remove the wheels again. Access is a little cramped but its perfectly feasible to remove and re-insert shock absorbers simply working from underneath the car standing on its own wheels. With the trim already removed removing swapping the shocks back for the old was a mere 10 min job!!
I had ordered the shocks from "buycarparts.co.uk" which seems to be a UK subsiduary of Autodoc GmbH in Germany. However I never got a response (still hope for advice) and went ahead to modify the top mounts. I drilled these out in the lathe to 9.8mm and then reamed them to 10mm. This is quite awkward but if you fit the metal spacer tube into the rubber mount you can clamp that in the chuck and it holds everything well enough to allow this minimum level of machining.
The spacer tubes were next, I
couldn't enlarge the bore of the Sachs spacers as this would leave the walls too thin. I therefore intended to use the 10 mm spacers and hope that the rubber can compress to accommodate any extra thickness. Here I got another surprise as the spacers in the 2 Sachs boxes were of different lengths and both were shorter that the Mapco spacer. I think this must mean that the spacer length Isn't critical as long as it permits the two rubber components to be compressed. It seemed the Monroe spacer might be too long for this so I machined them both down to the length of the longer of the two Sachs spacers
Fitting the rear shocks then proceeded in a very simple manner. The only problem being that I was unable to torque the top nuts to 20Nm because I couldn't hold the shock absorber shaft whilst using a torque wrench. However 20Nm isnt greatly tight and I found it was spanner tight using a test bolt on the bench. I did up the nuts as best I could and I dont think they will will be far off. Overall I think I would invest in the Nissan tool if doing this again (you need the 6.2mm size).
Be careful when refitting the trim and line the yellow floppy fastenings behind the stiff upper trim with their sockets using a long screwdriver poked in the side before popping the trim back on.
Yellow floppy fastener behind stiff upper trim. Position these using a long probe eg a screwdriver so they will engage with their sockets.
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