DDK - Die Deutschen Klassiker

Hi all

Looking for suggestions:

About 18 months ago I replaced my quite hard Michelin's for Pirelli Centuratos - the grip is certainly improved and gives more confidence in faster cornering however the front seems to have become quite bouncy - I have checked the tyre pressures and adjusted them to the suggested pressures from Longstone - as I remember 23 PSI ?

I have also checked the shocks and they are in working order.

So am I doing something wrong or is this the characteristic of the Pirellis ?


I would like to upgrade the front anti roll bar but only if I know that the tyres are acting as they should.

It could be that I have got used to the firm suspension of my daily (BMW M Sport) but thought that I should check if anyone else has experienced this with the Pirellis.

All the best

Regards Jeremy
1956 356A T1

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Are all your bushes in good condition - including the arb ones ?

What shock absorbers are fitted on the front ?

If you haven't already got them, I'd recommend Koni shocks (set to their softest on the front).

Upgrading to a thicker (17mm) arb would be the next step ...

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I'd also say that 23psi is too low - I found 26psi (F) & 28psi (R) suited mine (GT-style 356C) but I was running Avon CR6ZZ tyres.

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Jeremy,

About 20 years ago I had my car's front wheels off the ground for couple of weeks doing a job underneath the car. Finished the job and taking it for drive the front was really bouncy I could not work it out, I could push the car up and down and the shocks seemed to work and return but the bounce did not not go away. I still had the original Koni shocks stamped Porsche on them, and as everything else seemed okay to me I bought then two new Spax adjustable shocks that were on offer. Directly I replaced them the car was back to normal !!

I wondered or have wondered if air had entered the old Koni ones. I haver never established why they failed in the extended position but they did. The Spax ones have lasted well. I bought new Koni for the rear must be 10 years ago.

I have no other suggestions the tyres I have several different makes over the 53 years I have driven this car and never had bounce like the shock problem. Keep us informed I am interested to know how you get on.

Roy

Andy is right, I think that tyre pressure you are using it a bit on the low side. I have 185/70/15s Sprint Classics and use 26psi front and 28 psi on the rear to be better. I too have Konis, which are on the softest setting, and the ride is nice and plush, and feels very planted; but I am planning on adjusting them a little to firm things up a touch.

I had new KYB shocks on the car when it came from the USA, and they were terrible! Way too hard and jiggly.

Thanks for all your comments - it is really appreciated


I did have the tyres on 26psi but there was still this bounciness hence why I checked the Longstone website and was a little surprised by the low pressure guidance. I still have the Michelins so might do a test run with those on - that would then take the tyres out of the equation !

I will check the bushes - this is something I have not done for just over a year

I have Koni shocks - they were set in the middle as I was told to some years ago - but it would not be difficult to go soft and see how that reacts - at the same time while they are off, I will see if they are leaking or anything like that.

I will do each part and do my test drive route to see how each change reacts and if it stops the bouncing.

I was planning on the 17.5mm anti roll bar as the next improvement but wanted to make sure that all other areas have been covered off !

I will try to put a summary together for us all - if I have any success !! just got to wait for a suitable day to do this, avoiding recent gritting etc... !!

All the best

Regards Jeremy
1956 356A T1

Hi Jeremy, I had bounciness, so I replaced the front shocks, with Konis (bought from Andy!). I had sent thee to Andy Storer at Leda Suspension to rebush and dyno test. On his advice I set them to 3/4 hard and installed them. Great improvement. I then fitted a 17.5mm ARB from PRS and this has further improved the front end poise in corners, and incedentally it has also improved the way the car rides potholes...I'm on Avon CR6ZZ tyres which are very stiff, and I'm running 22 psi after much road testing. W

Thanks Winston

Sounds as if I was on the right track with the ARB from PRS

Just got to get the shocks checked and adjusted and all the bushes checked then !

Thanks a lot

Regards Jeremy

Jeremy if my left right tyre pressure balance is slightly off I get a bouncy frontend. I bought a digital tyre gauge off eBay for £5 which helps.

Sent from my M2004J19C using Tapatalk

Cheers Neil

I have become a bit obsessed with tyre pressures of late but will certainly make sure that they are matching

Many thanks

Regards Jeremy
1956 356A T1

Morning everyone

So I have been busy since all your emails and suggestions

I jacked up the car and checked for any play with the wheels. I found the offside had a little play in the the kingpin which I have cinched up - no play now. I also greased up all suspension parts too.

I then removed the shocks and found that they were already on their softest setting. I gave them a clean and swapped them round on each side, could not find anything untoward.

Tyres are now 26psi front and 28psi rear - there does seem to be some improvement with the tyre pressures but there still seems to be bounciness.

So I am confused !!!

One other item that seems to be exaggerating the issue are my seats, these are normal style and pretty springy. So this might be making the slightest bounce in the front worse with the bounce in the seats ?!?!?!!?

Couple of options might be to try next is maybe firm up the shocks by one turn or put my Michelin shod Sprintstars on the front to do a comparison ?

Maybe I am being too picky ?

Once I have done all I can then the upgraded Anti Roll Bar will follow !!

All the best

Regards Jeremy
1956 356A T1

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Maybe see if there is another 356A owner local(ish) to you that may let you have a drive of their car for comparison ?

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If you go to the front of the car and push down on the front how hard is it to get deflection? Does it easily bounce and down or do you have to really work quiet hard to get any up and down movement?

My car its hard to get any movement the shocks were set to medium. Only the smallest of movement if you press down
on the wings.

I think the softer the setting the more the bounce. Maybe my logical thinking is wrong but my car has no bounce.

Roy

Thanks for your responses

I think I will try one turn from softest and test drive and keep moving to the header setting until I find a suitable ride setting.

I know that the shocks work, while they were off I put them to full harness and could not compress them manually but could when set to softest.

I will try to get a ride in Ian MacMath's 356 next time I see him, which would be great as I can also experience his Speedster/GT seats !!

I will keep you posted

All the best

Regards Jeremy
1956 356A T1

I had problems with my car bouncing a few years ago, quite badly on the motorway.

The suspension was quite stiff after sitting for some time. I changed the dampers and the problem went away. I think part of the problem was old grease stiffening things up also.

I wouldn't think the ARB would be connected unless as these only come into play when cornering to keep your car level to the ground (I could be wrong as I'm no expert).

Good luck with it.