ice Needed on Front Shocks/Struts, Koni/Boge, Early vs. Late Options

[andys]

Got one good opinion "over there". Soliciting others.

I've got two options on shocks if indeed they are interchangeable. I'm doing a 911 front swap from a '89 Carrera. These are Boge struts with gas shocks; the black ones in the photos below.

When I disassembled the 914 struts, I found Koni adjustable inserts. The red shocks in photos below.

Should I consider trying to adapt the Koni inserts into the Boge struts? I seem to recall someone did a nice write-up on the different interchanges, and I think Koni inserts fit the Boge struts with a certain mix of parts (retaining spanner, spacer, etc). Since I have a machine shop, I can make whatever spacers I need if the adaption is even possible or worthwhile.

Another question I have has to do with which shock would be better suited to my setup. My car is a LS1 V8 swap with 6 speed trans. I have Koni double adjustable (Yellow) rear coil overs with 200# springs, Engman chassis stiffening kit and suspension ear reinforcement. The front T-bars are stock Carrera (18.8mm?). I would prefer to get the shocks reasonably close to matching the T-bars and the weight of the car. This is mainly a street car with of course a couple of visits to Willow Springs for a HPDE or two. Opinions?

Thanks,

Andys

[Bruce Hinds]

Andy,
It's been a long time since I put the 78 SC struts in my teener, but I was told at the time that I should use shocks for the teener, not that they fit different, but because the valving was different for the rear engine car and it would handle funny with the 911 shocks in the 914. I didn't need any special parts.
Bruce

[TravisNeff]

I believe you can find out what is interchangeable on the paragon-products.com site

[Richard Casto]

First, I can't speak to what might work well for your car. But if I was me and you already had Koni Yellow/Sport in the rear, I would consider putting Koni Yellow/Sport in the front as well.

Regarding the Koni Red, 911 Boge and 914 struts. Someone correct me if I am wrong, but aren't most 914 struts Boge? Have you tried removing the OEM Boge inserts from the 911 Boge strut and putting the Koni Red insert into the 911 Boge strut and use the hardware from the 914 Boge strut?

Basically I am thinking you may already have the required hardware in hand. I believe that the Koni strut inserts are sold on the assumption they are going into a Boge strut (as that was the most common style). And that you get a centering ring and a gland nut that work with the Boge strut. On the 911 and 914 Boge struts, at a minimum the spindles are different, but maybe the tops (diameter, thread, etc.) are the same? This way you might be able to use the same centering ring and nut on either strut. If for some reason the tops are not the same (such as maybe there is an early/late Boge gland nut?), I think you could probably find someone who might have the correct ring and nut but are not using them.

Worse case I would talk to Koni at their tech help line or Jason at Paragon to find out what works.

[andys]

I spoke with Jason @ Paragon; he was very helpful and yes Koni does (or did for my early Koni's) make a nut spacer to adapt their shock to the late Boge strut spanner nut.

What I would like to avoid is to over spring and over dampen the 914 front with the 911 stuff. Perhaps I can install the 911 complete, then worry about tuning it after I see the result.

BTW, that topic title should read "Advice Needed" not "ice Needed."

Andys

[brp986s]

I've heard of places that rebuild konis, but I have not done it. I bought bilstein 3.5" struts, took out the inserts and brought them to bilstein near san diego and had them revalved to 914 specs. It seems you want custom specs. They will ask for those when you drop them off. I don't know how you'll determine that.

Here is a table that was posted here some time back that correlates torsion bar diameter to spring rate:

SIZE ( mm) SPRING RATE ( Lb/in)
18.8 110
21 173
22 210
23 250
24 296
25 350

[MLedesma]

Uhmm, correct me if I am wrong but your Boge struts look like they actually have Bilstein inserts in them. Boge struts usually have a much thinner extension (similar to the Koni) on them. It looks like somebody did exactly what you except using the Bilstein instead.

Matt

[andys]

Matt,
Sorry I'm not particularly Porsche fluent, but I wasn't aware that Bilstein inserts will fit the Boge struts; anyone??
brp986s,
As a past racer, I always look toward adjustability options as I realize how important it is to tune the suspension to the conditions (street or track). I think the 914 T-bars are 17mm. The Porsche torsion bar conversion table I have differs significantly from the info you posted; do you perhaps have a link? Maybe someone has yet another conversion table (or link) to help establish the correct info?

BTW, does the foam T-bar seal go between the A-arm and the cross member, or between the cross member and the T-bar adjuster cap?

Thanks,
Andys

[Richard Casto]

IIRC, the Boge struts is the most common one used by Porsche. So for those who make replacement inserts (Koni, Bilstein, KYB, etc.), they designed their replacement inserts to work directly with the Boge strut because that is what most people have. It's the reason why Boge struts are the best starting point because everything fits.

I don't know Boge/Bilstein strut inserts well enough to tell you what type of insert you have right now in your 911 strut.

[Richard Casto]

Here is a good thread to read...

http://www.914world.com/bbs2/index.php?sho...ic=390&st=0

[andys]

Here is a good thread to read...

http://www.914world.com/bbs2/index.php?sho...ic=390&st=0

Richard,

Thanks for the link; it's a good read.

Andys

[bandjoey]

Where and who has the best prices on shocks and springs? thanks for the thread insert. Bill

[brp986s]

Matt,
Sorry I'm not particularly Porsche fluent, but I wasn't aware that Bilstein inserts will fit the Boge struts; anyone??
brp986s,
As a past racer, I always look toward adjustability options as I realize how important it is to tune the suspension to the conditions (street or track). I think the 914 T-bars are 17mm. The Porsche torsion bar conversion table I have differs significantly from the info you posted; do you perhaps have a link? Maybe someone has yet another conversion table (or link) to help establish the correct info?

BTW, does the foam T-bar seal go between the A-arm and the cross member, or between the cross member and the T-bar adjuster cap?

Thanks,:
Andys

the table is in a pdf that I have. In it is mention of http://tech.rennlist.com

[charliew]

Andy I know this is old but did you figgure out the black inserts are bilstein? Thats what I think they are because of the larger shaft. I have some bilsteins for either the 911 or the 914 it's one part number for either car that I am going to try and they have the large shaft.