73 S shock question

[Haasman]

My 73 911S 9113300709 needs shocks. It has been upgraded to 2.8 and is a fast car. It was built with Koni shocks (COA) and at least one shock has failed.

I am looking for suggestions-

My preamble: I am considering replacing the Konis with Bilsteins but it would mean replacement of the front struts. I believe I want to choose Bilstein Sports. A valued member has suggested only going to Bilstein HDs, because of the "too stiff compression". I haven't heard of this before. I am aware that Koni does rebuild their shocks in Tennessee I believe. Finally, I like and prefer gas charged shocks. I am not likely to scramble under the car to adjust the Koni shocks. I am very familiar with Bilsteins and Bilstein HDs. I will probably will never x-cross this car. I might track it but I am more interest in a well sorted, great handling fast car that me and the Mrs. can run with confidence anywhere any time.

Now, with all that being said, let me have it .... what do you think.

Sincerely,

Haasman

[John Z Goriup]

I strongly recommend the Bilstein, however I think all you'll need are the HDs. These were the standard shocks on the air-cooled Turbo 911s and are eminently suitable for the kind of driving you describe........they offer a very pleasant and effective ride without hammering you, the Mrs. or the car. I think you'll find the Sports shocks too firm for the street, since they are another 20% stiffer than the HDs. I don't believe there is any need whatsoever for re-valving a new set of Bilstein HDs. I have the HDs on my car ( '70 911T with a 3-liter which is used in the exact same driving you describe ) and find them perfect. If, after a time, you find you want to change the response of the HDs, you can always have them revalved at that time.

May I recommend Elephant Racing for the parts and installation..........for several reasons. You won't find a more competent supplier of top-quality suspension components and expertise, with a complete range of product offerings and installation / maintenance skills and abilities.........all at fair prices. You'll be in good hands with Chuck Moreland, proprietor, guiding you through a suspension review and suggestions, since if one of your Koni shocks has failed, I would think you'd want your entire suspension inspected for bushings, ball joints, etc. while you're in there.

See you Saturday at Canepa's ??

JZG

[Haasman]

I should add that a RS suspension is not objectionable to me. Obviously my S wouldn't be a RS (torsion bars/sway bars etc)

Thanks for the reminder John. We will be out of state this weekend.

Haasman

[Chuck Miller]

Haasman,

I have an original equipped Koni 73S that I put Koni Sport shocks on a few years ago... and I will have to say THEY DON'T MAKE IT EASY.

These are the 'new' (been around for years) 'yellow' Koni Sport shocks and inserts. The font inserts adjust through the top in the trunk with a handy plastic key. The rears are straight bolt-on replacements after you pre-set'm on the bench.

Now the fun part.... Koni sells Porsche replacement front inserts for almost everything except original Koni struted cars. Yes they do make'm but you have to really look hard to find them. Now when you do find them they will be sold to you WITH THE WRONG GLAND NUT. You will have a new Koni insert with it's new gland nut, that WILL NOT fit your old Koni strut. You will then have to call Koni USA in Kentucky an ask Jason (I hope he still works there) to sell you two new adaptive gland nuts # 73.25.01.011.1 for about an extra $15 each.

I'm not sure but I think you STILL have to go through this same dance if you order the stock red Koni inserts...

The shocks are fine.... the hassle is a PITA........

You can also get the nuts here:
http://www.automotion.com/koni-perfo...r-porsche.html

Pics of difference...

Hope any of this helps.....

[NorthernThrux]

I'll have to bookmark this for my future interest if I need to replace my Konis that came on the car (orange ones). I am intrigued by the comment that Koni will rebuild them. Is that true ? Certainly helps keep things original. If they do, is it roughly price competetive with the new yellow shocks ?

Ravi

[RSTarga]

Yes they still rebuild some of the shocks, you have to call them with the shock number for a quote. The Koni yellows are excellent shocks. I know everyone here prefers the Bilsteins but every bilstein I've ever had in the front gets a clunking noise from those inner bushings.

[Haasman]

I never have heard this .....
"......but every bilstein I've ever had in the front gets a clunking noise from those inner bushings."

Anyone else experience this?

Haasman

[chris_seven]

There seem to be several issues with front struts and making changes:

The Yellow Koni Inserts are incompatible with early Koni Strut casings for two reasons: (apart from the Gland Nut)

1. They are a different length
2. They have a small diameter post welded on the bottom of the insert and this doesn't fit the inside radius of the casing.



The post also does allow the insert to wander a little and this can cause long term issues.

We usually make up a 'bung' to drop into the bottom of the leg. This bung matches the radius , corrects the height and locates the insert.



It is commonly said that the Yellow inserts make the ride too harsh but there is overlap in damper rates between the original and the yellow inserts



Bilsteins shouldn't clunk and I have seen several threads on this subject over the last few years and there are a few reasons that this can occur, but I have used Bilsteins on Rally cars since the Seventies and never had this problem on a regular basis.

1. The DU bushes that locate the 40mm OD insert in a Bilstein Casing can wear with a significant amount of use. This ususally
takes many years and many tens of thousands of miles.
The bushes are replacable although the ones now sold by Bilstein in Europe are much shorter than the originals and around 3 x
the price of a GBB bush from a bearing shop.

2. Early SWB Boge legs are commonly converted to use a Bilstein insert and the current part sold by Bilstein (There used to be
two different Part Numbers available) are just a little too short and have some axial clearance. It needs a few shims dropping
into the casing to eliminate the clearance and allow the gland nut to lock the insert into place.

3. Later Boge casings can also commonly fitted with a Bilstein Insert made specifcally for the job.



I have seen examples in the UK where a standard Bilstein/Bilstein inverted insert has been fitted to a Boge leg.



These inserts are too small a diameter and will never locate correctly - the common practice is then to fill the gap with damper oil to stop the noise !!!

There have been some threads about this on some UK sites. I believe this is a reallybad practice and fundamentally dangerous.

The subject of HD Bilsteins is interesting as there is no rating specified as HD in the factory data.

If, as has been said, the HD is the standard Turbo setting then these are the 'softest' Bilsteins currently available:

Front is 148/108 rebound and bump and rear is 194/150.

The Part Number for the rear shown on the PP site is 24-001694 and this is the above setting.

I must say these settings seem a bit too 'comfort' oriented for my liking.

[Chuck Miller]

Chris,

Thanks for the comprehensive run-down on this...

As far as my 'Sport to original Koni strut set-up' ....we did figure out we needed a 'locator' at the bottom of the strut, so we made a couple of delrin o.d/i.d. bushings.

All and all it's VERY strange to me why we have to go through all this homework.... but then again, the manufacture of period specific vintage parts is no money maker for a big contemporary multinational company.

... and so it goes

[vtrich]

As you can see from my posting number, I'm really new to the early car world so pardon me if I'm way off base.
I always understood that the Bilstein HD and sport were differentiated by the length of the damper piston, where
the sport application would be used on a car that was lower than stock allowing full movement and
the HD on a stock ride height car. However, that seems to be inconsistent with my current 911 (3.2) because
it has HD on the front and Sport on the rear. That seems to be a common setup for my car, but since it was
installed by the previous owner I don't have any really good comparisons, except that I really like the way the car
handles.

I'm saying this all simply to place my vote in favor of Bilsteins. I've owned many cars with both Koni and Bilstein
shocks and I suppose this is somewhat personal, but I have always like the feel of the Bilstein cars better.

Just a noob $.02.

Rich