Koni or Bilstein ? Options

[Fazasport]

I am looking to replace the rear shocks and front strut inserts on my 1970 914. I will be using the car for tours, rallies, spirited driving and maybe an occasional Autocross not for track work. I am interested in a firmer ride than stock but not a harsh ride. The car does not have front or rear anti-roll bars currently.
If choosing between Koni or Bilstein which would provide the LEAST harsher ride quality?
I will also replacing the rear springs. With that in mind, should I stay with the stock 90lb springs or substitute that 100lb springs from the 914-6?

[Jack Standz]

We too are running Bilsteins all around, 100 pound rear springs, stock 911 front and stock 914 rear sways bars, raised spindles by 19mm with turbo tie-rods and stock 911 torsion bars. Our car is lower than stock and we run 16 x7 front and 16x8 964 wheels (D90) with 185/50 front and 245/35 rear tires.

When first driving this combination (with new control arm and trailing arm bushings), it was awful. Very harsh. Did not like it. Now after around 3k miles, it’s much better. Street only, so maybe next time less rear spring and softer torsion bars.

However, the current plan is to restore our ‘72 to very close to stock, but with the addition of front and rear 914 sway bars, leave spindle height alone, stock 4 lug Mahle wheels, etc. Already have stock rear springs and shocks/struts all around, wheels, sway bars, etc.

[mepstein]

We too are running Bilsteins all around, 100 pound rear springs, stock 911 front and stock 914 rear sways bars, raised spindles by 19mm with turbo tie-rods and stock 911 torsion bars. Our car is lower than stock and we run 16 x7 front and 16x8 964 wheels (D90) with 185/50 front and 245/35 rear tires.

When first driving this combination (with new control arm and trailing arm bushings), it was awful. Very harsh. Did not like it. Now after around 3k miles, it’s much better. Street only, so maybe next time less rear spring and softer torsion bars.

However, the current plan is to restore our ‘72 to very close to stock, but with the addition of front and rear 914 sway bars, leave spindle height alone, stock 4 lug Mahle wheels, etc. Already have stock rear springs and shocks/struts all around, wheels, sway bars, etc.

OK. I'm certainly no suspension expert but in my opinion, it's not the springs that are making the car harsh. The 19mm and 100lbs were on a stock 914-6. That car didn't ride harsh. I have found that some Bilstein HD shocks are very stiff and hash riding but not all of them. Maybe they don't have good consistency or maybe there are different production facilities and they are assembled slightly differently. Maybe they just need to break in. I don't know. Your tire size is also extremely low profile. Cars form the 70's definitely used the higher profile tires for shock absorption.

I bet if you went to higher profile tires and got the existing shocks rebuilt with custom valving, you would transform the ride for the better.

[Jack Standz]

We too are running Bilsteins all around, 100 pound rear springs, stock 911 front and stock 914 rear sways bars, raised spindles by 19mm with turbo tie-rods and stock 911 torsion bars. Our car is lower than stock and we run 16 x7 front and 16x8 964 wheels (D90) with 185/50 front and 245/35 rear tires.

When first driving this combination (with new control arm and trailing arm bushings), it was awful. Very harsh. Did not like it. Now after around 3k miles, it’s much better. Street only, so maybe next time less rear spring and softer torsion bars.

However, the current plan is to restore our ‘72 to very close to stock, but with the addition of front and rear 914 sway bars, leave spindle height alone, stock 4 lug Mahle wheels, etc. Already have stock rear springs and shocks/struts all around, wheels, sway bars, etc.

OK. I'm certainly no suspension expert but in my opinion, it's not the springs that are making the car harsh. The 19mm and 100lbs were on a stock 914-6. That car didn't ride harsh. I have found that some Bilstein HD shocks are very stiff and hash riding but not all of them. Maybe they don't have good consistency or maybe there are different production facilities and they are assembled slightly differently. Maybe they just need to break in. I don't know. Your tire size is also extremely low profile. Cars form the 70's definitely used the higher profile tires for shock absorption.

I bet if you went to higher profile tires and got the existing shocks rebuilt with custom valving, you would transform the ride for the better.

Tend to agree with you. Stock 911 front control arms with 911 torsion bars added stiffness. The 100 pound rear springs probably not too much.

New struts, new shocks, and new CA/TA bushings added stiffness/harshness, but the car is quite a bit less harsh now after breaking in, but still definitely stiffer than stock. The front 911 anti-sway bar, probably not a big contributor to harshness.

Yes, the low profile tires probably increased harshness some, but the wide and somewhat sticky rubber with low side walls added to a new LSD in the restored 901 transmission, it was something that just needed to be explored (IMG:style_emoticons/default/biggrin.gif) . These tires are somewhat past their "sell by" date due to the length of time it took to get this car back on the road so are being replaced with 195/50 and 225/50.

[mepstein]

We too are running Bilsteins all around, 100 pound rear springs, stock 911 front and stock 914 rear sways bars, raised spindles by 19mm with turbo tie-rods and stock 911 torsion bars. Our car is lower than stock and we run 16 x7 front and 16x8 964 wheels (D90) with 185/50 front and 245/35 rear tires.

When first driving this combination (with new control arm and trailing arm bushings), it was awful. Very harsh. Did not like it. Now after around 3k miles, it’s much better. Street only, so maybe next time less rear spring and softer torsion bars.

However, the current plan is to restore our ‘72 to very close to stock, but with the addition of front and rear 914 sway bars, leave spindle height alone, stock 4 lug Mahle wheels, etc. Already have stock rear springs and shocks/struts all around, wheels, sway bars, etc.

OK. I'm certainly no suspension expert but in my opinion, it's not the springs that are making the car harsh. The 19mm and 100lbs were on a stock 914-6. That car didn't ride harsh. I have found that some Bilstein HD shocks are very stiff and hash riding but not all of them. Maybe they don't have good consistency or maybe there are different production facilities and they are assembled slightly differently. Maybe they just need to break in. I don't know. Your tire size is also extremely low profile. Cars form the 70's definitely used the higher profile tires for shock absorption.

I bet if you went to higher profile tires and got the existing shocks rebuilt with custom valving, you would transform the ride for the better.

Tend to agree with you. Stock 911 front control arms with 911 torsion bars added stiffness. The 100 pound rear springs probably not too much.

New struts, new shocks, and new CA/TA bushings added stiffness/harshness, but the car is quite a bit less harsh now after breaking in, but still definitely stiffer than stock. The front 911 anti-sway bar, probably not a big contributor to harshness.

Yes, the low profile tires probably increased harshness some, but the wide and somewhat sticky rubber with low side walls added to a new LSD in the restored 901 transmission, it was something that just needed to be explored (IMG:style_emoticons/default/biggrin.gif) . These tires are somewhat past their "sell by" date due to the length of time it took to get this car back on the road so are being replaced with 195/50 and 225/50.

You may already know this but your 50 series front tire will be smaller diameter than your 50 series rear if the rear is wider. I believe you would use 55 on the front for a more similar diameter, maybe even 60.
Also, with bigger diameter tires, you can play around with tire pressure a bit more.
Don't underestimate comfort as a factor for enjoyment.