Bottoming out

Bottoming out

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Bull McCabe

Original Poster:

245 posts

252 months

Saturday 5th May 2018
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I have a 2500 running on adjustable AVOs all round, double springs and dampers on the rear.
I bought the car last year from an area of the country with better roads, so when I got driving on local roads the silencer in the middle of the car would bottom out on poorer surfaces. I wound the dials up on the shocks, which reduced the frequency of the car bottoming out, but this was at the cost of the ride being very harsh, which meant having to rapidly reduce speed when hitting a slightly uneven stretch of tarmac. Cars following on must have thought I was suddenly running on one cylinder as they glided along what seemed a smooth stretch of road.
I have recently raised the ride height and softened the shocks, which has made a huge difference, the changes in road surfaces are barely felt and the car is a much more pleasant ride, but it looks slightly odd riding higher. The flat corner plates of the chassis are 160mm from the floor. I will say that although the car is much more relaxed on poor roads, it feels slightly less precise and taut on a nice A road.
Reading through the history, a previous owner (from about 20 years ago) had written a letter to the next owner. In this letter he mentions that he cut the silencer out to solve the problem of the silencer hitting the tarmac, he actually says he liked the sound the car made without the box. Obviously, at the time the car didn't have adjustable suspension and this solved the problem.
I am wondering if I can find a happy medium of reasonable ride height, handling and comfort if I remove the silencer, lower the height and have the shocks somewhere in the mid range.
Will the noise of running without a silencer be too much to bear or should I just try to reach a compromise by making adjustments until I find the best settings for me?

Edited by Bull McCabe on Saturday 5th May 23:32

Bull McCabe

Original Poster:

245 posts

252 months

Monday 7th May 2018
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Thanks for the replies,

Over50, my exhaust is set as high as possible. There is minimal clearance between the chassis and the exhaust. I could try to alter the brackets for the rubber mounts to try to get it as high as possible, but I don't think it would take much before the exhaust would vibrate against the chassis. I will look into it next weekend though, because half an inch could make a big difference.

280i, yes, perhaps some more details would be good. It's a shame I only saw your reply now, as I had the car up on the lift earlier and could have taken some pictures. I know the car has had some suspension upgrades in the past, so perhaps I could post some photos up as soon as I get it back on the lift. I will try the level on the wishbones and let you know. I will post up some more info soon.

Thanks again

Bull McCabe

Original Poster:

245 posts

252 months

Tuesday 8th May 2018
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Alan,

I am running 185/65/15 at the moment. The car was running on 165/70s but they were 15 years old and far from confidence inspiring in the wet. Many sections of the local roads are poor and don't have camber to allow the rain to run off, so it is not unusual to find standing water so I was keen to put some new ones on with a decent wet rating. The car bottomed out on the tyres I got it with, which is why I firmed up the shocks. I was just fishing to see if there were any tips I could pick up. I have since wound the height down again, to a mid point and firmed the shocks slightly and it does seem a slight improvement. I will just keep fiddling to try and find the optimum.
The exhaust system is a Heath Robinson with the 2 silencers welded in, so I can also have a look to see if I can find silencers with a shallower depth.

Thanks again for the replies.