Top Mounts Early and late / 968

[924Srr27l]

Does anyone know if the later Top Mount shock absorber piston position is Higher
than the Early Type ?

The Early 924S / 944 ones had a Rubber Donut underneath the plate, the
later ones the Rubber block was thicker above it and I'm wondering if
the position of the piston rod is higher up on the later types which would
have an effect of allowing more travel.

I know The strut bracket distance went smaller and the hole spacing different and also the
Spring ID went smaller too, I also suspect the later cars were lower than the Early 944
and maybe the Top mount design was changed to place the piston rod further up for more travel ?

R

 

[924Srr27l]

You'll be able to find answers to all of your questions when they occur. No matter what the issue, one of the learned folks here will have an answer for you..
regards
Pete

 

[Waylander]

the 968 top mounts 951 343 018 04 are now NLA according to PET

 

[924Srr27l]

the 968 top mounts 951 343 018 04 are now NLA according to PET

Probably, but I was hoping to find out if the early and late types position the top
of the piston rod in the same or a higher position?

The Strut Angle to the stub axle (Spring Motion Ratio) is different on from 924s / early 944
v later offset 944's & 68, I wonder if because of this more acute angle Porsche decided to have more
rubber about the top mount plate as opposed to underneath like the early Doughnut design ?

R

 

[924Srr27l]

Ground Control USA (To Major Tom!)

Make these Top Mounted, Adjustable Suspension Strut Top mounts, where their extra height
mounted on top of the Chassis gives the Piston rod and Shock Absorber more suspension travel.

The Gold Plates Bolt up from underneath strut towers.

This saves buying new shock absorbers with shortened stroke piston rods and is ideal for lowered Road
or Track based cars.

As you can see they have a good rage of Castor an Camber adjustments which can be done on the car at the road
or trackside, but they do use a Spherical bearing which will NOT absorb any vibrations and chassis jolts like the
OE Rubber mounts do, and it's this that I'm looking for a solution.

I'm either thinking design and have a made a Vibration material Spacer, or have plates made as above which
the OE Mounts can bolt inside the centre.

R

 

[944Turbo]

I have the KLA fixed spherical bearing plates on my coupe - they did not noticeably make an adverse difference to the amount of vibration/harshness or noise into the car, the sphericals were shot after about 20k road miles though, and needed replacement. I did cut up an old neoprene backed mousemat and fitted it to the top of the damper rod to stop dirt and spray from getting to the underside,
Tony

 

[924Srr27l]

I have the KLA fixed spherical bearing plates on my coupe - they did not noticeably make an adverse difference to the amount of vibration/harshness or noise into the car, the sphericals were shot after about 20k road miles though, and needed replacement. I did cut up an old neoprene backed mousemat and fitted it to the top of the damper rod to stop dirt and spray from getting to the underside,
Tony

Ok, but were these solid mounts used with Standard 952 shock absorbers and Springs or Different ones, and what Diameter Rims?

R

 

[944Turbo]

With standard 1990 Turbo shocks with techart springs and then later with leda shocks and springs all with 17" rims, 968 MO30 ARBs, big black calipers, up to around 330Bhp, They were used with various track rubber but most of the miles were on the road on road rubber.
http://www.klaindustries.net/strtmnt/strtmnt.htm
My lower wishbones have a delrin front bush and 944 MO30 rears.
Tony

 

[924Srr27l]

With standard 1990 Turbo shocks with techart springs and then later with leda shocks and springs all with 17" rims, 968 MO30 ARBs, big black calipers, up to around 330Bhp, They were used with various track rubber but most of the miles were on the road on road rubber.
http://www.klaindustries.net/strtmnt/strtmnt.htm
My lower wishbones have a delrin front bush and 944 MO30 rears.
Tony

Ok thanks, I'm still not 100% convinced that any NON rubber mount (solid mount) won't be felt from the cockpit!
I'm thinking of designing a top mounted plate first that will take the rubber do-nut and try that.

My car is so much lighter than any transaxle it does not have the same amount of loading and hence all the parameters,
spring rates and valving need to be very different from the normal road orientated Suspension kits from Spax, GAZ, AVO, KW, and Bilstein etc..because they are too hard.

I've spoken to all of their technical departments and they all informed me their kits are too hard for such a lightweight car so I will have to find a different route with some calculations etc.. Which is pretty much what i've done.

Spax Sport Inserts (Not RSX) and 190 Lbs Front 2.25ID race coil springs, which will be changed next year to 2.5ID 163Lbs. The rear T bars are 220Lbs but the Motion ratio brings these down to approx 140lbs, as does the front motion bring the current 190's down to an actual 160lbs. The Front is harder than the rear but slightly saved by 18mm ARB. The tyre pressures also reflect the LOAD loss at 26psi all round on 205/55/16 all round.

R

 

[Indi9xx]

The GroundControll kits are great, I have used them on 944's, 968's and 964's

I have also used a number of different kits on 924's and 944s over the years and not noticed any additional road noise, which really shocked me when I first drove one of the modified cars all the way to essex back to back with a standard car.

 

[924Srr27l]

The GroundControll kits are great, I have used them on 944's, 968's and 964's
I have also used a number of different kits on 924's and 944s over the years and not noticed any additional road noise, which really shocked me when I first drove one of the modified cars all the way to essex back to back with a standard car.

Not suspension Kits ? I'm referring to Spherical bearing top mounts v the OE Rubber ones.

R

 

[Indi9xx]

Me too, not used anything else they make, just the adjustable top mounts.

The originals are pretty reliable, mainly the bearing goes which can be replaced, but now the cars are getting old, the rubbers are beginning to perish and are certainly changing in their dynamics of rigidity/flex and potentially even geometry.

They will go into production again, if they are not available again already, a bit like 968 M030 anti roll bars or 944 sills.

 

[924Srr27l]

Me too, not used anything else they make, just the adjustable top mounts.
The originals are pretty reliable, mainly the bearing goes which can be replaced, but now the cars are getting old, the rubbers are beginning to perish and are certainly changing in their dynamics of rigidity/flex and potentially even geometry.
They will go into production again, if they are not available again already, a bit like 968 M030 anti roll bars or 944 sills.

Ok, when you said you'd "used a number of different kits" this sounded to me like Suspension not top mounts.

So you've used the GC Mounts, top or underneath versions?

I'd be shocked if a Spherical bearing top mount was not Harsher than OE Rubber Mounts, my 924S uses the same as the early 944's and the Rubber Do nut and bearing is still available hence I fitted brand new ones,

The early style have the Rubber lower set in the plate, the later 86? onwards the "puck" is higher up which
I heard was because of the Increased Strut Angle? with the longer wishbone / ET50's Offset front suspension?

Do you know what the two different front suspension motion ratio's are 924S & early 944 v late 944 & 968 ?
I wonder if the scrub radius changed too or they adjusted the design somehow? I still maintain having owned
all 4 (track width) incarnations the "best front end feel & Turn in" is the narrow track 924S ,
and NOT the early 944, or later 944 / 968. Maybe it's the Power steering that disguises this but it shows up more with a Manual rack?


R

 

[Indi9xx]

I was shocked also.

Some of the first solid top mounts I used were TAS items in the 1990's which were solid billet aluminium with a replaceable spherical ball and holes all around the outside, so you could turn the whole assembly and dial in more camber while reducing caster, which on the one hand seems counter productive, but in the real world with any one application you are often finding yourself wanting more of one or the other and not able to dial in any more due to the limits of the standard adjustment.

These were on a 968 where I wanted more caster than available, but also wanted a more rigid overall geometry.. I warned the customer that it would probably not unpleasant on the drive to and from the track, but when I delivered the car back to him in Essex (About 140 miles away from Bournemouth) I was amazed that on the whole journey there wasnt an increase in road noise, which considering my daily at the time was a 968 CS I was very used to how they sounded... The only increase in road noise was during one patch of the M25 that used to be (or maybe still is) concrete and on every expansion joint the car sounded like it had a bad CV joint at road legal speeds.

As recently as this summer we fitted a 924S with some adjustable KW top mounts, which again did not sound overly noisy on roads. But then again, most of the road noise in cars isnt mechanical noise transmitted through the suspension in my opinion, but noise generated by the tyres, which is then picked up by the bodywork near the tyre and transmitted into the car... I think with solid top mounts you might have a different story with a worn out wheel bearing, where the rumbling is transmitted through the suspension and into the body though, where a solid top mount combined with a bad wheel bearing would probably sound much worse than on a car with rubber top mounts.

 

[Indi9xx]

And yes, the redesign in top mounts was mainly because the shock absorber angle is different in a late offset car.. But also I believe (in 944s) it was because of the increase in weight also, which required the top mount to be a little stronger perhaps.

 

[924Srr27l]

I was shocked also.

Some of the first solid top mounts I used were TAS items in the 1990's which were solid billet aluminium with a replaceable spherical ball and holes all around the outside, so you could turn the whole assembly and dial in more camber while reducing caster, which on the one hand seems counter productive, but in the real world with any one application you are often finding yourself wanting more of one or the other and not able to dial in any more due to the limits of the standard adjustment.
These were on a 968 where I wanted more caster than available, but also wanted a more rigid overall geometry.. I warned the customer that it would probably not unpleasant on the drive to and from the track, but when I delivered the car back to him in Essex (About 140 miles away from Bournemouth) I was amazed that on the whole journey there wasnt an increase in road noise, which considering my daily at the time was a 968 CS I was very used to how they sounded... The only increase in road noise was during one patch of the M25 that used to be (or maybe still is) concrete and on every expansion joint the car sounded like it had a bad CV joint at road legal speeds.
As recently as this summer we fitted a 924S with some adjustable KW top mounts, which again did not sound overly noisy on roads. But then again, most of the road noise in cars isnt mechanical noise transmitted through the suspension in my opinion, but noise generated by the tyres, which is then picked up by the bodywork near the tyre and transmitted into the car... I think with solid top mounts you might have a different story with a worn out wheel bearing, where the rumbling is transmitted through the suspension and into the body though, where a solid top mount combined with a bad wheel bearing would probably sound much worse than on a car with rubber top mounts.

Blimey, there's a blast from the past ! Steve Fell Trans Auto Sport that was! now he's doing Compbrake. I also worked in the Road & race tuning Industry in the 90's
when TAS was a Supplier.

Maybe I take a punt on the GC top mounted Top mounts then, I could fit a 3mm thick gasket (shaped anti vibration material)
KW V3 have that high compression valve which makes the ride comfortable over potholes and high speed compressions, Intrax also have something similar
which I like the sound of.

Is this also why the 968 CS Top mounts have weighed sections on them for vibration resistance?

R