Jump to content
Sign in to follow this  
Buchanan Automotive

968 "Green Stripe " clutch pressure plate

Recommended Posts

This week we installed a new clutch into a customers recently purchased Porsche 968 & with this 968 being a near concourse condition 968 & with the customer very unhappy with the amount of effort required to push down on the clutch he ( the owner ) wondered was there something we could do to reduce the effort needed , because as is his wife refused to drive it & to give you some guide on what this car was like to operate the clutch , well, it felt just like my 968 & all the other 968's I / we have driven in the last 20 + years & thats because the only clutch kit you could purchase from Sachs  "Never" ever came with the special 968 pressure plate , from Sachs the "kit" ( aftermarket least expensive ) pressure plate was for the 964 ( 911 , 1990-1993 "Blue Stripe" ) = heavier clutch pressure plate diaphragm spring.

So even though this 968 was relatively low kms indicated and the overall cosmetic condition is exceptional I was pretty sure it has had a clutch replacement done at some stage in its life & it was the the Sachs ( aftermarket) 968 clutch kit & that means it gets the only pressure plate Sachs can supply = the 964 "blue Strip " one = heavier than normal clutch pedal pressure 

So we removed the old clutch from this 968 and sure enough it was the blue strip ( 964 one ) , but before I removed it I wanted to find out if Porsche Germany could still sell us the correct one ( green stripe )  = less pressure & correct one for the 968 & the great news was they had stock of the "green Strip" one in Germany & yes it has its very own part number , now this is where it get interesting because when I last enquired about these years & years ago they ( the 968 one ) was NA or even NLA which means you buy what you can & that made the Sachs ( aftermarket) kit the only choice .

Note 1 )   When new the 968 had a clutch components ( 3 ) & dual mass flywheel made by three different companies , the pressure plate ( green stripe ) was made by Lockheed in the UK , but the 968 only clutch plate ( friction plate ) & the 968 only release bearing assembly were made by Sachs of Germany & naturally the dual mass flywheel was made by LUK of Germany & the 968 dual mass flywheel is unique to the 968 

Note 2 )  Some years after the 968 was discontinued the Lockheed (  Porsche genuine only ,green strip ) pressure plate spare parts stocks were used up & at some stage later Porsche has had them remade & the new Genuine Porsche 968 "green Strip" pressure plate is made in Italy , how do I know its made in Italy ?  , the one I ordered from Porsche Germany two weeks ago & when we opened the box , on the alloy pressure late casing it states "made in Italy " not the UK , like the rear original ones were , and it had the "Green Stripe " identification of pressure plate spring force

So we did the usual , removed the old dual mass flywheel & had the surface lightly radial machined to get rid of the hot spots ( very important for getting rid of clutch shudder ) and being a relatively low km 968 , the condition of the internal springs within the dual mass were OK ( not many machine shops will or want to machine a dual mass ,because the surface moves unless locked in some way , new spigot bearing , new 968 Sachs friction plate , new Sachs 968 release bearing , new flywheel bolts  & new pressure plate bolts & the new genuine Porsche "Green Stripe " 968 pressure plate 

Oh my God , what a difference , it brings back memories of what these were like when there were new at the Porsche dealership I worked at all those decades ago , its that good , nothing else compares to it for use as a road car 

I have already order the same for my 968 , its that good I don't even want to drive my 968 much more until I get rid of the incorrect pressure plate 

Regards

Bruce & Sean Buchanan
Buchanan Automotive

Share this post


Link to post
Share on other sites

Bruce,

I would love to get your thoughts on the clutch history and offerings for the 944 S2 and Turbo models. What is your preferred clutch plate, pressure plate, flywheel combination for these (I realise it will depend on torque etc for a modified Turbo)? How do you feel about the recent Spec 'push' type offerings that eliminate the clutch fork and slave cylinder?

Share this post


Link to post
Share on other sites

Great info Bruce,

Pedal pressure was a concern for me as well but I just thought of it as good exercise! 

I noted the price increase in clutch operating cylinder and managed to get one at the old price. In doing that I noted the S2 one was much less in price but exactly the same with one exception being the angle of the bleed screw. This was for clearance at the rear but on measuring found I should be able to use one so got a spare. Porsche also do not list a seal kit for the 968 one but the one listed for S2 is the same dimensions so could be used rather than buy the whole unit if that is the problem.

Also interested on above unit for 968 ?

Cheers, Mark.

Share this post


Link to post
Share on other sites

Hi Justin , as you know the clutch size & the flywheel size are different between the 944S2 & the 951  .

So lets take the 944S2 , as a road car we only use the standard 944S2 "Sachs " clutch kit & the operating pressure is nice , meaning the clutch pedal pressure is quite light and as a road car , the Sachs kit is perfect

944S2  ( road registered ) and mostly used on the road , but occasionally used at a Porsche Club Supersprint events , the standard Sachs clutch kit is fine "So" long as the human driving the car at the track matches the RPM in down shifting perfectly , because the standard 944/944S2 road clutch plate ( friction plate ) will not tolerate too many poor down shifts that results in partial rear wheel "Chirp" / lock up , you will break the center out of these road clutch' s  , we do keep in stock a competition clutch plate for this poor driving style , but the stronger 944 /944S2 ( track )  friction plate will cause a lot of clutch SHUDDER in road driving , very hard to live with as a road car , but it will not break on the track being driven poorly .   We generally get the owner of the said car to supply what ever they think they want or they think is the "Go"
--------------------------------------------
951 ( road registered ) and even with some Porsche Club Supersprints , we find the standard "Sachs " clutch kit is fine , even with the 951 with around 350 - 400HP , no issues at all , however saying that we tend to ( on clutch replacements ) use a Sachs combination }

Clutch plate  }  from Pelican parts ( example only ) the Sachs "Sport" spring hub .w/organic lining  ( Higher Friction ) , these have less springs , but bigger ones , quite a good clutch plate , in fact Sean uses this very plate in his 580+ HP 3.0L 16v 951

Pressure Plate  }   Standard 951 ( Sachs ) pressure plate

Release bearing } Standard 951 ( Sachs ) release bearing
----------------------------------------------
Sean's 3.0L 16v 951 uses }

Clutch plate  }  The Sachs one mentioned above

Pressure plate }  KEP  stage 2

Release bearing  }  standard Sachs 951 release bearing

------------------------------------------------

Regards
Bruce Buchanan

 

Share this post


Link to post
Share on other sites
1 hour ago, Buchanan Automotive said:

Hi Justin , as you know the clutch size & the flywheel size are different between the 944S2 & the 951  .

So lets take the 944S2 , as a road car we only use the standard 944S2 "Sachs " clutch kit & the operating pressure is nice , meaning the clutch pedal pressure is quite light and as a road car , the Sachs kit is perfect

944S2  ( road registered ) and mostly used on the road , but occasionally used at a Porsche Club Supersprint events , the standard Sachs clutch kit is fine "So" long as the human driving the car at the track matches the RPM in down shifting perfectly , because the standard 944/944S2 road clutch plate ( friction plate ) will not tolerate too many poor down shifts that results in partial rear wheel "Chirp" / lock up , you will break the center out of these road clutch' s  , we do keep in stock a competition clutch plate for this poor driving style , but the stronger 944 /944S2 ( track )  friction plate will cause a lot of clutch SHUDDER in road driving , very hard to live with as a road car , but it will not break on the track being driven poorly .   We generally get the owner of the said car to supply what ever they think they want or they think is the "Go"
--------------------------------------------
951 ( road registered ) and even with some Porsche Club Supersprints , we find the standard "Sachs " clutch kit is fine , even with the 951 with around 350 - 400HP , no issues at all , however saying that we tend to ( on clutch replacements ) use a Sachs combination }

Clutch plate  }  from Pelican parts ( example only ) the Sachs "Sport" spring hub .w/organic lining  ( Higher Friction ) , these have less springs , but bigger ones , quite a good clutch plate , in fact Sean uses this very plate in his 580+ HP 3.0L 16v 951

Pressure Plate  }   Standard 951 ( Sachs ) pressure plate

Release bearing } Standard 951 ( Sachs ) release bearing
----------------------------------------------
Sean's 3.0L 16v 951 uses }

Clutch plate  }  The Sachs one mentioned above

Pressure plate }  KEP  stage 2

Release bearing  }  standard Sachs 951 release bearing

------------------------------------------------

Regards
Bruce Buchanan

 

I've got the KEP Stage 1 PP, Sachs Sport disc combo and I really like it. Factory smooth engagement and only slightly more pedal effort than the stock PP. Holds ~500Nm just fine, perfect combo for a moderately powerful 951 IMHO. Have you had any issues with the clutch fork and the Stage 2 PP? I remember reading that the clutch forks used to break fairly often with the extra clamping force.

Share this post


Link to post
Share on other sites
11 hours ago, 9fan said:

Great info Bruce,

Pedal pressure was a concern for me as well but I just thought of it as good exercise! 

I noted the price increase in clutch operating cylinder and managed to get one at the old price. In doing that I noted the S2 one was much less in price but exactly the same with one exception being the angle of the bleed screw. This was for clearance at the rear but on measuring found I should be able to use one so got a spare. Porsche also do not list a seal kit for the 968 one but the one listed for S2 is the same dimensions so could be used rather than buy the whole unit if that is the problem.

Also interested on above unit for 968 ?

Cheers, Mark.

Hi Mark , the slave cylinder ( I think that is what you mean ? ) is different on the 968 compared to a 944S2 as the bore dia is different which means different piston and seals , & yes the seal kit is only available for the  944 / 944S / 951 / 944S2 up to & including the 1991 year model & also fits the early 928 series slave cylinder  ( up to 1986 )

Where as the clutch master cylinder ( R / H / D ) 931 , 944 , 944S , 951 , 944S2 up to & including the 1989 model part number = 478 721 171 is quite different to the Clutch master cylinder ( R/H/D ) 1990 year model onwards 944S2 , 951 & 968 , part number 945 423 149 00 

Regards
Bruce Buchanan

Share this post


Link to post
Share on other sites
10 hours ago, Buchanan Automotive said:

Hi Justin , as you know the clutch size & the flywheel size are different between the 944S2 & the 951  .

So lets take the 944S2 , as a road car we only use the standard 944S2 "Sachs " clutch kit & the operating pressure is nice , meaning the clutch pedal pressure is quite light and as a road car , the Sachs kit is perfect

944S2  ( road registered ) and mostly used on the road , but occasionally used at a Porsche Club Supersprint events , the standard Sachs clutch kit is fine "So" long as the human driving the car at the track matches the RPM in down shifting perfectly , because the standard 944/944S2 road clutch plate ( friction plate ) will not tolerate too many poor down shifts that results in partial rear wheel "Chirp" / lock up , you will break the center out of these road clutch' s  , we do keep in stock a competition clutch plate for this poor driving style , but the stronger 944 /944S2 ( track )  friction plate will cause a lot of clutch SHUDDER in road driving , very hard to live with as a road car , but it will not break on the track being driven poorly .   We generally get the owner of the said car to supply what ever they think they want or they think is the "Go"
--------------------------------------------
951 ( road registered ) and even with some Porsche Club Supersprints , we find the standard "Sachs " clutch kit is fine , even with the 951 with around 350 - 400HP , no issues at all , however saying that we tend to ( on clutch replacements ) use a Sachs combination }

Clutch plate  }  from Pelican parts ( example only ) the Sachs "Sport" spring hub .w/organic lining  ( Higher Friction ) , these have less springs , but bigger ones , quite a good clutch plate , in fact Sean uses this very plate in his 580+ HP 3.0L 16v 951

Pressure Plate  }   Standard 951 ( Sachs ) pressure plate

Release bearing } Standard 951 ( Sachs ) release bearing
----------------------------------------------
Sean's 3.0L 16v 951 uses }

Clutch plate  }  The Sachs one mentioned above

Pressure plate }  KEP  stage 2

Release bearing  }  standard Sachs 951 release bearing

------------------------------------------------

Regards
Bruce Buchanan

 

Thanks Bruce. I appreciate the info.

You have me curious on the differences and interchangeability of the S2 and Turbo clutch/pressure plate kits. What clutch did you end up using in Nik's white 944 S2 3L 16v Turbo? From what I've read he started with a stock S2 setup. I've heard from one or two people that recommend the Turbo clutch plates as a more sturdy upgrade for S2's. I'm not sure if that's even possible though and what the limiting factor is (clutch plate thickness, diameter etc). I gather there are stronger than stock kits for S2 that don't shudder and can handle more abuse and/or torque.

Share this post


Link to post
Share on other sites
On 10/8/2018 at 10:07 PM, OzJustin said:

Thanks Bruce. I appreciate the info.

You have me curious on the differences and interchangeability of the S2 and Turbo clutch/pressure plate kits. What clutch did you end up using in Nik's white 944 S2 3L 16v Turbo? From what I've read he started with a stock S2 setup. I've heard from one or two people that recommend the Turbo clutch plates as a more sturdy upgrade for S2's. I'm not sure if that's even possible though and what the limiting factor is (clutch plate thickness, diameter etc). I gather there are stronger than stock kits for S2 that don't shudder and can handle more abuse and/or torque.

Hi Justin , they are NOT interchangeable , meaning the 944 S2 ( stepped ) flywheel has to take the smaller diameter 944/944S2 clutch plate & matching smaller pressure plate ,where as the 951 clutch plate ( larger diameter ) will not fit , you can NOT intermix 944/944S2 flywheel & clutch parts with the very different 951 flywheel & 951 clutch plate ( larger ) 951 pressure plate ( larger ) , even the 951 release bearing is different , even the 951 clutch fork is different

You can not fit a 951 flywheel into a 944S2 because the trigger wheel teeth number are different ( engine will not run ) , + you need a 951 Bell Housing & then a 951 engine wiring harness & 951 engine management system

Now with Nik's old car , it started life as a standard 944S2 coupe ( 2nd hand car ) and Nik experienced the performance of Sean's 3.0L 16v 951 ( E85 fuel ) and was entranced .

So we started with a 3.0L 944S2 , the advantage there is we have the 3.0L 16v engine & the low ratio final drive as opposed to the standard higher ratio 951 final drive ratio that we do not want , but we were going to NEED from the Very Beginning of the build  the 951 clutch set up & the 951 flywheel ( different number of trigger teeth and correct dia for the 951 clutch ) , we then needed a 2nd hand 951 engine bell-housing  & a 2nd hand 951 engine harness & 951 ECU's ( engine management ) & running a piggy back Vitesse system

Naturally we had to lower the compression ratio of the engine , stronger aftermarket pistons & stronger aftermarket con-rods , custom made inlet manifold & custom made exhaust manifold & a Vitesse stage 5 turbo & the car runs two maps , one for E85 & another for 98 premium unleaded

We knew from the start what we needed to control the 580+ HP and that was }

951 Flywheel
951 Bell-housing
KEP II  pressure plate ( for a 951 )
951 / Porsche / NEW clutch fork ( remember we did this years ago when we could still purchase the new fork from Porsche )
Sachs 951 sport clutch plate ( because it will be driven on the road we needed to reduce shudder as much as possible)
951 release bearing

The above clutch has been in the car for years and years & has copped a flogging & still working

Regards
Bruce B

 

Share this post


Link to post
Share on other sites

Thanks Bruce. I should have realised it would never be so straight-forward. So it’s a bellhousing, flywheel and ECU on top then. 

I was looking to future-proof my next clutch install on the S2 with a higher rated Turbo model but it sounds like it may not be worth it. There goes my 3L 16v turbo build for now. :P 

Share this post


Link to post
Share on other sites

All this talk of green stripe or blue strip or heavy or light clutches and such nonsense....Another reason why a tiptronic box is the way to go 🤩

Share this post


Link to post
Share on other sites
11 hours ago, OzJustin said:

Thanks Bruce. I should have realised it would never be so straight-forward. So it’s a bellhousing, flywheel and ECU on top then. 

I was looking to future-proof my next clutch install on the S2 with a higher rated Turbo model but it sounds like it may not be worth it. There goes my 3L 16v turbo build for now. :P 

Hi Justin , you do not have to do the 3.0L 16v Turbo ( project ) like we did , we just wanted to use a known "Strong " clutch / drive-line set up from the word go & we knew full well that at 580+ HP accelerating flat out coming out of a corner at a race track with 11' wide rear wheels with new very stick "R" spec tyres , something has to give and a small"ish" 944/944S2 clutch will not do the job we need to make that part of the equation as reliable as possible , so hence the 951 set up

Remember Porsche spent a lot of money at the time to change all those parts on the original  220HP 951 ( 1986 model ) , meaning from the very beginning the 951 had }

Different bell housing
Different flywheel ( larger contact area for a larger clutch )
Different ( larger / stronger ) clutch pressure plate
Different ( larger stronger ) clutch friction plate
Different clutch fork
Different release bearing

And all that re-engineering expense was for a 220 HP (1986 - 1988) 951

When you think of it , its all quite logical & its not rocket science

Regards
Bruce Buchanan 
Buchanan Automotive

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×