Tuesday, November 30, 2010

Playing with the shocks

When I first got the car way back in 1998, I felt the back was a little inclined to float at speed, and commented to my favourite Alfa mechanic about it. In response he stiffened the rear shocks, mentioning afterwards that he had to take the back axle out to do it.

That comment made me wary of touching them again, and even though ever since I've found the car a bit too stiff, I've left the shocks alone. Driving it again after six years though, it definitely felt not just stiff, but over-damped, so the shocks went on to the list of items to be addressed.

Sunday had been designated as a day to take the car for an extended drive and see what was what, but with the weather being so bad, instead I spent a few hours just looking the car over and starting to address a few things.

First item on the list was to identify the shocks and confirm how they are adjusted. Turned out they are Koni Reds. The Reds are Koni's direct replacement for the OEM shock. The question remains of how these ones are valved - are they standard 105 Alfa spec, and do they differ front to back (Alfa 105 series cars have very soft rear suspensions and much firmer front).

Reds are adjustable for rebound, although Koni recommend installing them set to fully soft, and adjusting only for wear. Adjustment is a bit fiddly to do because in theory you should remove the shock from the car.

I decided to set the fronts to full soft as an experiment as they are more accessible (rears sit inside the springs), and found that after disconnecting the upper mount I could easily collapse the shock and engage the adjuster. Both front shocks were set about half a turn from full soft, and I reset them to full soft.

Next I confirmed that the rears are also Koni Reds. At that point I was inclined to wait until I had a spring compressor so I could remove the springs and get at the shock properly, but in the end decided that there was nothing to be lost by giving it a go in-situ. Once again I disconnected the top mount. Because of the closed shock tower there was no way to get my hand to the shock body to collapse it, but I was able to use a screw driver to gently push on the top mount stud and collapse the shock. With fingers reaching between the spring coils I was then able to turn the body and engage the adjuster. Again, both shocks were set about a half turn from fully soft, and I reset both to fully soft. Next time I might try disconnecting the lower mount instead, as I think it might be easier to push the shock up from below when engaging the adjuster. It might also be better to support the car on the chassis instead of part of the unsprung mass, which compresses the spring and shock.

With the wheels back on the car, I dodged rain clouds for a quick test drive. Definitely a change - car felt more compliant, and I could feel the suspension moving more. First impression was that possibly the front needs a bit more rebound, but back seemed better. Actually I think that the back would probably benefit from more compression damping, but certainly not rebound.

Test drive showed up another small problem - the gear knob which I had put on the previous day came loose. 5 minute job with an allen key to fix that, and the new knob, with a longer body to extend the throw, is a nice improvement to the shift.

Following the test drive, made an attempt to discover why the auxiliary electric fan isn't working - it will be needed once the weather gets hotter. Traced the wire and confirmed that the fuse is good, but will need a multimeter to investigate further.

I discovered (and created!) two more issues during the afternoon... The wing mirror, which was a bit wonky anyway, caught on the car cover when I was taking it off, and broke off. While doing the shocks I took the opportunity to give the suspension a bit of a shake test at each corner. The FR caster arm has a tiny bit of play in it, which is probably the ball joint and will need to be sorted. Rest of the suspension looked good, but if one BJ is failing there will be others.

1 comment:

  1. Well, turns out I wasn't as clever as I thought I was with the shock adjustments. See this post for details: http://timsricciardi.blogspot.com/2010/11/worlds-stupidest-alfa-owner.html.