Koni Shock Setting for any 356 Carrera

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Bill Sargent
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Koni Shock Setting for any 356 Carrera

#1 Post by Bill Sargent » Sat Oct 26, 2019 3:10 am

My 59 A cab with the 2 liter 4 cam motor was bouncing quite a bit with the Boge shocks - seems like the shocks are too soft to cope with the extra 100 pounds of motor. Since it has the 2 liter 4 cam motor I figure the closest comparison is a Carrera II.

I have purchased a set of the Koni Classic shocks for the car. Does anyone with a Carrera II have experience on a good setting for the shocks - both front and rear? Absent other advice I plan to set them at the half way point of their adjustment. I have the same shocks on my bone stock 64C cab set all the way soft and they are good for that car.

Thanks in advance for any direct experience that you can pass on.
Last edited by Bill Sargent on Sun Oct 27, 2019 12:39 am, edited 1 time in total.
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Thomas Sottile
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Re: Koni Shock Setting for Carrera II

#2 Post by Thomas Sottile » Sat Oct 26, 2019 9:38 am

I can’t see how 100 lbs could make such a difference possibly the shocks are just bad

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Re: Koni Shock Setting for Carrera II

#3 Post by Martin Benade » Sat Oct 26, 2019 9:49 am

My konis did not please me much until they had a few hundred miles on them, then they rode much better. I am pretty sure I didn’t imagine this.

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Re: Koni Shock Setting for Carrera II

#4 Post by Bill Sargent » Sat Oct 26, 2019 3:39 pm

I guess I should have been more specific.

Does anyone owning or maintaining a Carrera II have a recommendation on Koni Shock settings?
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Re: Koni Shock Setting for Carrera II

#5 Post by C J Murray » Sat Oct 26, 2019 4:13 pm

Do the torsion bars need need to be stiffer?
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Re: Koni Shock Setting for Carrera II

#6 Post by Martin Benade » Sat Oct 26, 2019 9:16 pm

I know I wasn’t a person with that hands-on knowledge but I am afraid the number of Carrera II s that are actually driven and have Koni Classic shocks may be tiny.

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Re: Koni Shock Setting for Carrera II

#7 Post by Bill Sargent » Sun Oct 27, 2019 12:23 am

Per the parts books:

Torsion Bars
front torsion bars were the same for 356 A, B & C/SC.
rear torsion bars were the same for 356 A, B and SC. 356 C got a softer rear torsion bar.
Shock Absorbers
front shocks for the A super and Carrera were called out as Koni with a different part number. All other 356 A, B and C had the same front shock part number, including the Carrera IIs.
Rear shocks were called out as Koni with a different part number for the A super and A Carrera. Koni's were a parts book option for the Carrera II

As far as torsion bars go, my car would be the same as any Carrera so I do not think torsion bars are the problem. Plus the car is not bottoming out. It is bouncing without sufficient damping after bumps, especially at the rear; hence my thinking the shocks are the problem.

Shocks on the car are Boge purchased from Stoddard (with Porsche part numbers stamped on them) in early 80s and have about 4K miles on them. They have no free play and feel fine by hand - but perhaps over the course of time they have gone bad.

Since it appears that 356 A carreras came with Koni's, and all other Carreras had this option, that widens the potential pool of owners who might have useful information. I will check with Chip Perry off line.
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Re: Koni Shock Setting for any 356 Carrera

#8 Post by Harlan Halsey » Sun Oct 27, 2019 3:30 am

Bill,
I don't have a Carrera II but I do have an A Carrera and an SC. Both have had the same Konis as long as I have owned them, more than 30 years. I set Koni's one turn up from full soft, and that's it.

In general shock absorbers are really spring dampers. The damping can be under damped, that is "bouncy" the car goes through several cycles; critically damped, the car overshoots once, that is the condition you want; or over damped, it returns to neutral without over shooting at all. A shock which is too weak either by design or wear allows the car to "bounce". It is easy to test shocks just by pushing a fender down, Konis damp only the rebound. Some racing shocks are "50/50" meaning that they resist the compression as well as the rebound but that tends to result in an unnecessarily hard ride on the street.

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Re: Koni Shock Setting for any 356 Carrera

#9 Post by Vic Skirmants » Sun Oct 27, 2019 7:02 am

"Per the parts books:

Torsion Bars
front torsion bars were the same for 356 A, B & C/SC.
rear torsion bars were the same for 356 A, B and SC. 356 C got a softer rear torsion bar."

Not exactly: The A and B cars had the long torsion bars, while C cars had the short ones.

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Re: Koni Shock Setting for any 356 Carrera

#10 Post by C J Murray » Sun Oct 27, 2019 9:24 am

Vic Skirmants wrote:
Sun Oct 27, 2019 7:02 am
"Per the parts books:

Torsion Bars
front torsion bars were the same for 356 A, B & C/SC.
rear torsion bars were the same for 356 A, B and SC. 356 C got a softer rear torsion bar."

Not exactly: The A and B cars had the long torsion bars, while C cars had the short ones.
And pre-A had short ones that were larger diameter making them the stiffest.

I am surprised the big Carrera lump didn't get slightly larger diameter torsion bars in back.

The clock position of pushrod 356s is different for Speedsters and coupes and Carreras must be different. Have you corrected your camber in the rear?
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Re: Koni Shock Setting for any 356 Carrera

#11 Post by Martin Benade » Sun Oct 27, 2019 9:59 am

I don’t believe Konis only damp rebound. I think only rebound can be adjusted. Does anyone know how the various versions differ?

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Re: Koni Shock Setting for any 356 Carrera

#12 Post by C J Murray » Sun Oct 27, 2019 10:15 am

The adjustment on basic Konis is rebound only. Rebound adjustments are more noticeable than compression changes. Rebound can make a dramatic change in car balance during cornering and braking.
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Re: Koni Shock Setting for any 356 Carrera

#13 Post by Geoff Fleming » Sun Oct 27, 2019 12:17 pm

The Carrera 2 also was equipped with the compensator spring at the rear, which, as the name implies, compensated for the weaker torsion bars, ( and heavier engine), by giving the rear more support. It did nothing to substantially increase the handling though, in fact, would actually exert downward force against the axles which is not something good for a swing axle car.
Without the compensator, the rear end of the car would sit very low, so the bar gave a bit more up- lift against the transmission and added somewhat to the driving comfort in daily road use.

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Re: Koni Shock Setting for any 356 Carrera

#14 Post by Jeff Adams » Sun Oct 27, 2019 12:40 pm

Studying the little spec book on this subject, I found what may be some incorrect information. From what I know, the info on the Pre A through B cars is correct.
Pre A: 25mm diameter, 553mm length "short"
A and B: 24mm diameter, 627mm length "long"
A and B with camber compensator bar: 23mm diameter, 627mm length "long"

The 356C and Carrera 2 is where it can get confusing, especially when looking at the spec book. The standard 356C bars are 22mm diameter and shorter than the A/B bars. However, the spec book shows the diameter at 22mm (correct) but length at the same 627mm "long" as an A/B car. However, the C bars are shorter and used with a closed end cover. Not sure of the overall length on a C.

Carrera 2 cars were made in both B and C versions. All Carrera 2's came standard with a compensator bar from the factory. However, the 356C Carrera 2 did not use the same short length 22mm diameter bar as the standard pushrod engine C and SC. It used the same setup as the 356B, 23mm diameter bar 627mm length. I am not sure what the engineering (or bean counter) reason was for not using the shorter 22mm "C" on 1964 and 1965 Carrera 2 cars.

Bill - for your car, a 1959 356A Cabriolet with the heavier 2 liter engine that was never used by the factory that year, there is no factory standard for bars and installed angles. My subjective opinion would be:
24mm rear bars. No factory camber compensator. Vic's camber regulator, street version. 1 to 1.5 negative rear camber. With 24mm torsion bars and Vic's bar, not sure what angle to set the trailing arms at to get the desired ride height and camber setting.

Shocks, I am not really a fan of the Boge's on any 356. The Koni's seem to give all cars a better feel. Hard to say if your current Boge's are the cause for your car bouncing, the only way to know is install a new set of the same shocks or go to Koni's. I like to start softer at about halfway in between and move up from there. Shocks are easy to disconnect and adjust, so be ready to try some different settings and let us know what you like. I am thinking somewhere between halfway and three quarters is what will be best.

Looking at the online version of the Porsche parts book, the same shock was used on both pushrod and Carrera cars: "Vibration damper blue, 644.333.501.13" I think part of your question is whether there was a different shock used just for Carrera 2. I don't think so. If there was, good luck finding that exact shock today in good condition. Current issue new Koni's for 356 are probably the best you are going to get.

Your post is timely for me, as we have a customer who is getting ready to build the same car: a 59 Cabriolet with a 904 engine. This thread and your experience will help me out. Vic and John Willhoit, feel free to chime in here and agree or disagree.
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Re: Koni Shock Setting for any 356 Carrera

#15 Post by Jeff Adams » Sun Oct 27, 2019 1:18 pm

Here is some more random trivia and thoughts related to the torsion bar page in the little spec book.

I don't think the camber compensator bar came out until 1960. However, the spec book shows what setup should be used for 356A. As a retrofit? Does anyone know if the compensator came out and was available in 1958 or 1959??

Most people seem to agree that the compensator bar did nothing to improve handling. However, the spec book shows all 356B GT having bars installed. What did Jennings and other hardcore racers use back in the day? I would think the standard 24mm bar and no compensator would be the way to go.

The spec book shows entries for both 356B GS and GT Carrera Roadster, which is curious as this was not a standard production car - only 2 were ever made both special order. One was a GS, one GT. The 356C Carrera 2 GT entry is also weird, only one ever made. All the rest were T6 356B cars

Part number 644.333.101.01 is a 24mm bar, for either left or right. The 23mm camber compensator bar and 22mm 356C bars have different part numbers for left and right. Anyone know why?

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