bouncy car

[al joyce]

Hi,

I have a 1960 convertible and it is very bouncy. I bought a pair of new shock absorbers to go on the rear. So far I have removed the off side one and discover that the old shock absorber has more resistance than the new one which so far I have not bothered to fit as I am unsure that this is going to be better. So my question is why is the ride so bouncy and what should I do about it?

[svenedin]

A few questions:

1) Is your car entirely standard suspension front and rear?
2) When you say bouncy, does the car bottom out on the suspension e.g when going over a speed hump?
3) What is the general condition of the front and rear suspension (leaf springs, bushes etc)?
4) Are they the correct leaf springs?

Bouncy (i.e not being damped) does sound like a damper issue. I personally would fit your two refurbished dampers at the rear and see what happens. You may have the same issue at the front however. The drop links being in good condition are of course essential for proper operation of the dampers.

Tyres do affect the ride too. The type of tyre, make of tyre and inflation pressure.

I have a 1969 factory convertible that I have completely rebuilt the suspension of front and rear. That includes refurbished dampers x4, new leaf springs (from a specialist spring manufacturer), new polyurethane bushes and pads, new drop links. The handling has been transformed. It was a marathon of work but long overdue. I have had the car for 34 years and I had become too used to it being skittish, imprecise and wandery. The tired worn out leaf springs had far too much give and the back was very bouncy. Dampers were also in poor condition.

Stephen

[kevin s]

The old dampers have probably got very old fluid in them, could well be this breaks down when it's in use and you lose damping, you probably could just change the fluid (this made ours much better), but my experince is they then develop leaks, I'm giving up on lever arms and going telescopic!

[myoldjalopy]

Yes, I entirely changed the fluid in the front dampers a while back in my car, and they then both developed leaks. But why should that happen?

[svenedin]

Yes, I entirely changed the fluid in the front dampers a while back in my car, and they then both developed leaks. But why should that happen?

Because the seals are worn out

Stephen

[kevin s]

it must be more than just that, ours were bone dry but within a week of changing the fluid (they were full of the old stuff) it's pouring out.

I wonder if the modern stuff has different creep proprties to the original

[svenedin]

it must be more than just that, ours were bone dry but within a week of changing the fluid (they were full of the old stuff) it's pouring out.

The old oil may be decades old and may have been topped up over the years but never drained and changed. The oil breaks down chemically into a thin fraction and a sludge. The sludge probably has some effect to bung up the leaky old seals. When there's new oil in there it leaks through the worn seals because most of the sludge has been drained out but the new oil probably dissolves any remaining sludge. A similar thing happens when cleaning out old radiators. They weren't leaking but once cleaned up and refilled they do.

Stephen

[kevin s]

The old oil smelt awful, not like gear oil more fishy and as you say some of it had a lumpy stringy cosistency.

I might yet have a go at repairing the old ones depends if I can find the time.

[svenedin]

The old oil smelt awful, not like gear oil more fishy and as you say some of it had a lumpy stringy cosistency.

I might yet have a go at repairing the old ones depends if I can find the time.

Yes the old oil absolutely stinks. I suppose it is possible the original oil contained Whale oil but I do not know for sure. Certainly my grandfather who was a clockmaker used Whale oil and some vegetable derived oils too. Basically they go off eventually but petrochemical oils also chemically change over time.

Stephen

[philthehill]

Was the new rear damper(s) filled with oil and exercised before fitting?
The damper should be mounted as per the BMC Manual and exercised to get the oil all around the damper and to exclude air. Once exercised top up the damper with oil - then the damper can be fitted to the car.

[al joyce]

Thanks everyone for the replies. Not quite sure what "excised" means? The dampers came from ESM and I assumed they were good to go straight on.

I have read that people do not like the new springs from ESM so is it possible to get old ones re tempered and if so where?

[svenedin]

Exercised. Clamped in a vice and the lever moved up and down.

You could enquire with a spring manufacturer whether they can re-temper your springs. If not, get new ones. Mine came from Jones Springs and I am very pleased with them.

Stephen