Ride Quality---shock comparison

[Bill Verburg]

Originally Posted by faverymi

Bill:

Can you share who provides this service?

Thanks

Bilstein San Diego or Elephant Racing

[tirwin]

Originally Posted by Driven97

I'm being pedantic, but that's backwards. Digressive shocks ramp up forces very quickly at low shaft speeds for good body control in transitions, then taper the gain off at high shaft velocities for bumps.

You made me question my memory. I went back and looked at the plot that came with my re-valved Bilsteins. I had to guess at what a linear curve would've looked like but my plot is not nearly as aggressive on the low force/velocity as your picture indicates so I wasn't thinking of it in as stark of a contrast as your picture indicates.

I think the main point is that the curve is non-linear and can be customized. I suspect that the people who do this sort of work have what they believe is their own 'secret sauce' setup that varies based on vehicle, setup and owner wishes, so apples/apples comparisons are probably tricky.

In my situation, I have raised spindles, adjustable bump steer tie rods ends, 21/28 t-bars, new bushings, etc. I love the setup. For me, I was able to achieve a much less rough ride quality and get a tighter handling experience. I was afraid it would be more harsh than when I started but it has been quite the opposite. I love the fact that I can hit a pothole or big dip in the road and have full suspension travel and no upsetting of stability. It was a huge improvement for me, but maybe not everyone's cup of tea.

Getting back to the OPs issue, the harshness can come from several things. Basically something is not dampening road force or force is being transmitted through components. Most likely worn out components like bushings or struts.

My point was IF you are changing the struts then take Bill V's advice and consider digressive curve. If you already had the Bilsteins, it would be a no-brainer because revalving the old ones is cheaper than buying new ones.

[Jameel]

I think all my posts end up at the same destination: fix it right and be done with it. I know what I'll be doing this winter.

I did talk with Elephant racing and they did say the Bilsteins are much better all around than the stock Boge shocks. I think I'll make the switch.

[myslateblue911]

Originally Posted by tirwin

You made me question my memory. I went back and looked at the plot that came with my re-valved Bilsteins. I had to guess at what a linear curve would've looked like but my plot is not nearly as aggressive on the low force/velocity as your picture indicates so I wasn't thinking of it in as stark of a contrast as your picture indicates.

I think the main point is that the curve is non-linear and can be customized. I suspect that the people who do this sort of work have what they believe is their own 'secret sauce' setup that varies based on vehicle, setup and owner wishes, so apples/apples comparisons are probably tricky.

In my situation, I have raised spindles, adjustable bump steer tie rods ends, 21/28 t-bars, new bushings, etc. I love the setup. For me, I was able to achieve a much less rough ride quality and get a tighter handling experience. I was afraid it would be more harsh than when I started but it has been quite the opposite. I love the fact that I can hit a pothole or big dip in the road and have full suspension travel and no upsetting of stability. It was a huge improvement for me, but maybe not everyone's cup of tea.

Getting back to the OPs issue, the harshness can come from several things. Basically something is not dampening road force or force is being transmitted through components. Most likely worn out components like bushings or struts.

My point was IF you are changing the struts then take Bill V's advice and consider digressive curve. If you already had the Bilsteins, it would be a no-brainer because revalving the old ones is cheaper than buying new ones.

Tim,

I just switched from 16's to 15's on my 83' SC Coupe running Toyo R1R 205/50 & 225/45. Then I had the car lowered to a similar profile as I had when running the 16's. Once those changes were made, The ride quality seemed to suffer becoming noticeably more "harsh". I have been trying to decide if going with a 60 aspect ratio tire on my 15's would not only raise the car up a bit (it is very low right now) but also create a more compliant ride.....Now I am shifting my focus to the suspension on my car to perhaps make the ride more smooth and less jarring.

I was intrigued by your statement in this thread.....

"For me, I was able to achieve a much less rough ride quality and get a tighter handling experience."

This sound like exactly what I would like to achieve. Any specific tips you can provide for me on my suspension set up (bushings, shocks, etc...) would be greatly appreciated.

[Driven97]

Every complaint about bad ride quality has the words "car is lowered" in there. I wonder if it's a coincidence?

[Tremelune]

Originally Posted by Driven97

Every complaint about bad ride quality has the words "car is lowered" in there. I wonder if it's a coincidence?

I think this is it precisely.

My car was at roughly stock height (within 5mm of 16mm up front and 108mm in the rear, as measured from torsion bar center to hub center) and the ride quality was just what I was looking for, and the roll was fine. It drove like your brother's. I brought it to a highly regarded race shop to dial in the height more precisely and have it aligned and corner balanced and they convinced me to lower it an inch or two. Now it drives like your car. No other changes were made.

I try to avoid terms like "stock", "US", and "Euro" when discussing ride height as I've found they mean different things to different cars and different people. Most measure from the fenders anyway, and that introduces variables like tire size, pressure, and chassis variations.

Modern shock internals (custom digressive valving) will get you a better compromise of motion control vs ride quality, but I strongly suspect raising your car will get you the ride your after. That said, it's a grand either way, and with new shocks you'll have better damping, which will also be a benefit if you decide to raise the car in the future.

Actually, what's the story with that? If you raise/lower a car an inch or so, should damping ideally be changed to compensate?

[Bill Verburg]

For a given set of t-bars and sway bars and assuming the shocks aren't bottoming, ride quality is solely a function of bushings, shock and tire sidewall characteristics.

For a better ride
use rubber bushes, the softer and more compliant the better
use softer, taller sidewalls at lower pressures on narrower wheels
use more compliant lower rate shocks digressive valving tames the low speed response no matter the rest of the valving character

For better performance
use stiffer rubber or solid bushes
use shorter stiffer sidewalls at higher pressures on wider wheels
use higher rate shocks but still w/ digressive (or more esoteric) valving

Of course there is an upper and lower limit to all the above, you need to stay w/i the design range of the equipment.

All else being equal lowering alone isn't going to degrade ride, But the lower you go the more bump and the closer to the shock motion range limit you get, so that other steps may be necessary.

w/ 7 & 8 x15s ranked from worst ride to best
205/50 & 225/45
205/55 & 225/50
195/65 & 215/60
185/70 & 185/70

205/55 & 225/50 on 7 & 8 x16 will have a better ride than the same on 15 because of the taller sidewall, on 6 & 7 will have a better ride than on 7 & 8 because the sidewalls have more play etc etc.

[Tremelune]

Indeed, I suspect our suspensions are beginning to bottom out on modest bumps and potholes. There was a pronounced change in the ride quality of my car when it was lowered with no other changes.

[H-viken]

Originally Posted by Bill Verburg

205/55 & 225/50 on 7 & 8 x16 will have a better ride than the same on 15 because of the taller sidewall

Bill, since the height of the side wall is a fraction of the section width of the tire, would the sidewalls not be identical, whether it's a 15" or 16" wheel? The outer diameter would be different though.

Johan

[Bill Verburg]

Originally Posted by H-viken

Bill, since the height of the side wall is a fraction of the section width of the tire, would the sidewalls not be identical, whether it's a 15" or 16" wheel? The outer diameter would be different though.

Johan

There about a 1% difference in effective radius, which is what you are riding on, and which is due to sidewall deformation for RA1 (just a typical example) 225/50 x15 vs 225/50 x16 when mounted on the same 7" width wheels, The actual amount varies by an individual tires idiosyncrasies

[KNS]

Isn't it common thinking that Boges ride more "comfortably" than Bilsteins? I realize Bilsteins are a higher quality shock, can they be valved for more comfort?

[tirwin]

Originally Posted by myslateblue911

Tim,

I just switched from 16's to 15's on my 83' SC Coupe running Toyo R1R 205/50 & 225/45. Then I had the car lowered to a similar profile as I had when running the 16's. Once those changes were made, The ride quality seemed to suffer becoming noticeably more "harsh". I have been trying to decide if going with a 60 aspect ratio tire on my 15's would not only raise the car up a bit (it is very low right now) but also create a more compliant ride.....Now I am shifting my focus to the suspension on my car to perhaps make the ride more smooth and less jarring.

I was intrigued by your statement in this thread.....

"For me, I was able to achieve a much less rough ride quality and get a tighter handling experience."

This sound like exactly what I would like to achieve. Any specific tips you can provide for me on my suspension set up (bushings, shocks, etc...) would be greatly appreciated.

Some background...

I acquired my '83 in 2011. Back then you could get a solid SC for around $15k. I thought I was going to track the car. By the time I finished getting most of the major projects done, SC prices went up significantly and now I have angst about tracking it like I had originally intended (and my job is getting in the way now!). The reason I'm saying this is because I'm not sure I would've made all of the same decisions in hindsight.

When I first got the car, the ride quality was pretty awful. It was a completely stock setup of 16x6/7 Fuchs with Continental Extreme Contact DSW(?) tires. If I drove over railroad tracks it made my teeth rattle. If I hit a pothole it speed it seemed to de-stabilize the car. The front ride height had been lowered. The angle of the tie rod to the A-arm was severe. Nothing had been done to account for bump steer. When I would back out of my driveway or drive over a speed bump the steering rack would jerk left/right.

When I started thinking about refreshing the suspension I started reading Craig_D's thread -- '78 SC Elephant Racing Suspension Rebuild.

At some point I happened to be on a business trip in the Bay Area and I had a 1/2 day free so I called Chuck Moreland at Elephant Racing and asked if I could drop by. Chuck sat down with me and we discussed a plan. If I was to do it over again I would probably have done the rubber bushings but I am still pleased with the setup.

Here is what we did:

Rear
ER adjustable spring plate
ER polybronze spring plate bushings
28mm SAW torsion bars
Sent Chuck Bilsteins for digressive curve revalve
Rubber sway bar bushings
Adjustable sway bar drop links
Rubber trailing arm bushings (originally bought monoballs but decided against them)

Front
ER Spherical control arm bushings
21mm SAW torsion bars
Sent Chuck Bilsteins for digressive curve revalve
Raised the front spindle (20mm if I remember correctly)
Adjustable sway bar drop links
Rubber strut top camber plate bushings
Loemforder ball joints
Turbo tie rods
ER adjustable tie rod ends

Now I'm running 17x7.5/9 Linea Corse wheels. Tires are 225/45/17 front and 255/40/17 rear.

I spent some time trying to find the comment in Craig_D's thread and couldn't find it but I remember him talking about the feeling of hitting a big dip on the freeway where they were doing some paving. He was expecting a jarring hit and instead it was nothing. I would say that is the feeling I have now. The suspension is tight but compliant. Having full suspension travel makes an amazing difference.

The only thing left on the "to do" list is adjustable sway bars.

Bottom line -- "feel" is subjective. If you're considering making a change, try to find some locals who have different setups and go for a ride with them to see if you think you would be happy with it.

[chrismorse]

Originally Posted by Jameel

I think all my posts end up at the same destination: fix it right and be done with it. I know what I'll be doing this winter.

I did talk with Elephant racing and they did say the Bilsteins are much better all around than the stock Boge shocks. I think I'll make the switch.

Changing T bars, ride height or bushings all require corner balance and re-align.
This is not a small cost, so, get these parts carefully selected.

Changing shocks, wheel tire, or anti roll bars does not.

But, you need to be honest with yourself and the sales people you are relying on for critical advice.

There is a powerful demon drawing you toward a full on, kick ass, racing suspension.

Good luck,
Chris

[PorscheRally]

Originally Posted by Bill Verburg

For a given set of t-bars and sway bars and assuming the shocks aren't bottoming, ride quality is solely a function of bushings, shock and tire sidewall characteristics.

For a better ride
use rubber bushes, the softer and more compliant the better
use softer, taller sidewalls at lower pressures on narrower wheels
use more compliant lower rate shocks digressive valving tames the low speed response no matter the rest of the valving character

For better performance
use stiffer rubber or solid bushes
use shorter stiffer sidewalls at higher pressures on wider wheels
use higher rate shocks but still w/ digressive (or more esoteric) valving

Of course there is an upper and lower limit to all the above, you need to stay w/i the design range of the equipment.

All else being equal lowering alone isn't going to degrade ride, But the lower you go the more bump and the closer to the shock motion range limit you get, so that other steps may be necessary.

w/ 7 & 8 x15s ranked from worst ride to best
205/50 & 225/45
205/55 & 225/50
195/65 & 215/60
185/70 & 185/70

205/55 & 225/50 on 7 & 8 x16 will have a better ride than the same on 15 because of the taller sidewall, on 6 & 7 will have a better ride than on 7 & 8 because the sidewalls have more play etc etc.

Hi Bill,

This is great info for me.

Based on the above info, can we say that 17" wheels will never have the street ride comfort of the 16" wheels or any of the 15" tyre combinations?

The reason I am asking this question because I have 15"&16" wheels but the tyre selection/availability for these wheels getting very difficult over here in our market whereas 17" have a good selection. Although, I don't have 17" wheels in hand I am planning to buy some quality 17" wheels however I don't want to sacrife the street comfort ( mainly city driving and highways but also considering some rather poor surface back roads - broken asphalt with patholes etc )

Of course, I am aware of the fact that tires are the critical part of the equation but I am also prepared to equip my own car (1986 3.2 - may be 3.4 later on ) with the correct suspension bits. I have been reading the related topics but couldn't see much info with the suspension set up with the 2 or even 3 way adjustable shocks. I don't know, may be they are preferred more with the track day drivers and not much taken into consideration by the owners who is seeking for the most comfortable street cars.
For example, apparently KW came out with the so called variant 3 shocks for the G model cars which seemed very interesting. However, KW only has the low speed and rebound adjustability but not the Hi speed adjustability. That is pre-set. This made me think twice because, if I understand correct, we can get the best ride quality ( comfortable street driving with occasional canyon carving let's say ) with the professionally revalved digressed Blisteins and matching TBs, swaybars etc.
So, this is a bit confusing.
Shouldn't the 2/3 way ( especially the 3 way adjustability) be the best of the best when it comes to comfort setting if required.
I understand that normally, 2/3 way adjustable shocks mainly intended for the track and/or motorsport use but is not there any other KW like shocks which would give us a
comfortable but tight ( if needed or desired) modern day ride ?
Am I totally thinking in the wrong direction or is it just the matter of a budget for the project ?
Last but not least, for example, is there a way to have 17" wheels set up and still have a great comfort with the correct ingredients with the adjustable shocks and the matching components ? ( with the acceptance of the limits of the chasiss torsional flex which can not be changed on a road going car )
Regards
Kerem

[Trackrash]

I think that some of you are not considering the intended use of the car and how sticky the tires you are running.

When I was running, on 7 and 8 x 16" Fuchs, Bridgstone potenzas with 19 and 26mm torsions with 19mm sways, and raised spindles, and lowered to 24,5 and 24", all was fine. Even when autocrossing.

Then I changed to R compound tires, Toyo RA-1s. Suddenly my car was leaning and pitching on the autocross tracks.

So now its 22 and 30mm torsions with 22mm sways and Koni externally adjustable shocks. The larger torsions are a trade off. They are a little harsher over small bumps but actually better on dips and potholes, since the suspension doesn't bottom out. Bottoming out will will rattle your teeth for sure.

Where did this leave me? If I have my shocks set on soft and my tire pressure is on the lower end of the acceptable range, it rides fine. If I set my shocks up like I want them on the track and have the tires up to optimal pressure for the track I don't even want to drive it on the crappy roads around here.

Life is all about compromises. How low and stiff do you need to go?

[Trackrash]

Another thing to consider is the firmness of the driver's seat.

A compliant seat, like the longhoods came with, will go a long way to dampen sharp road inputs.

[911pcars]

"So when driving around rough city streets or highways with pronounced expansion joints, my car exhibits more of a sharp "bang-bang" and I can feel it in the seat."

As with many threads on a car forum, a straightforward diagnostic question segues to lists of preferred mods and other related topics. In this case, complete front end overhaul with aftermarket/factory pieces to personal suspension setups. Revalving shock curves is way overkill for a street car, but folks w/large budgets do manage to find various ways to spend it. Upgrades are fine, but perhaps overkill as it relates to diagnosing an obvious malfunction rather than "what's causing the noise?"

As some had suggested, check both front/rear suspension for abnormal wear. It could be worn bushings (sway bar support, control arm, upper shock mount), or an internal shock malfunction.

It also could be a part that is loose (anything related to suspension, steering, etc.).

Worn shocks should have been replaced as a set.

A trusted local Porsche tech can help wonders.

Sherwood

[myslateblue911]

Originally Posted by Bill Verburg

For a given set of t-bars and sway bars and assuming the shocks aren't bottoming, ride quality is solely a function of bushings, shock and tire sidewall characteristics.

For a better ride
use rubber bushes, the softer and more compliant the better
use softer, taller sidewalls at lower pressures on narrower wheels
use more compliant lower rate shocks digressive valving tames the low speed response no matter the rest of the valving character

For better performance
use stiffer rubber or solid bushes
use shorter stiffer sidewalls at higher pressures on wider wheels
use higher rate shocks but still w/ digressive (or more esoteric) valving

Of course there is an upper and lower limit to all the above, you need to stay w/i the design range of the equipment.

All else being equal lowering alone isn't going to degrade ride, But the lower you go the more bump and the closer to the shock motion range limit you get, so that other steps may be necessary.

w/ 7 & 8 x15s ranked from worst ride to best
205/50 & 225/45
205/55 & 225/50
195/65 & 215/60
185/70 & 185/70

205/55 & 225/50 on 7 & 8 x16 will have a better ride than the same on 15 because of the taller sidewall, on 6 & 7 will have a better ride than on 7 & 8 because the sidewalls have more play etc etc.

Mr Verburg,

Excellent reply as always. I appreciate your thoughtful consideration. This information is helpful

[myslateblue911]

Originally Posted by tirwin

Some background...

I acquired my '83 in 2011. Back then you could get a solid SC for around $15k. I thought I was going to track the car. By the time I finished getting most of the major projects done, SC prices went up significantly and now I have angst about tracking it like I had originally intended (and my job is getting in the way now!). The reason I'm saying this is because I'm not sure I would've made all of the same decisions in hindsight.

When I first got the car, the ride quality was pretty awful. It was a completely stock setup of 16x6/7 Fuchs with Continental Extreme Contact DSW(?) tires. If I drove over railroad tracks it made my teeth rattle. If I hit a pothole it speed it seemed to de-stabilize the car. The front ride height had been lowered. The angle of the tie rod to the A-arm was severe. Nothing had been done to account for bump steer. When I would back out of my driveway or drive over a speed bump the steering rack would jerk left/right.

When I started thinking about refreshing the suspension I started reading Craig_D's thread -- '78 SC Elephant Racing Suspension Rebuild.

At some point I happened to be on a business trip in the Bay Area and I had a 1/2 day free so I called Chuck Moreland at Elephant Racing and asked if I could drop by. Chuck sat down with me and we discussed a plan. If I was to do it over again I would probably have done the rubber bushings but I am still pleased with the setup.

Here is what we did:

Rear
ER adjustable spring plate
ER polybronze spring plate bushings
28mm SAW torsion bars
Sent Chuck Bilsteins for digressive curve revalve
Rubber sway bar bushings
Adjustable sway bar drop links
Rubber trailing arm bushings (originally bought monoballs but decided against them)

Front
ER Spherical control arm bushings
21mm SAW torsion bars
Sent Chuck Bilsteins for digressive curve revalve
Raised the front spindle (20mm if I remember correctly)
Adjustable sway bar drop links
Rubber strut top camber plate bushings
Loemforder ball joints
Turbo tie rods
ER adjustable tie rod ends

Now I'm running 17x7.5/9 Linea Corse wheels. Tires are 225/45/17 front and 255/40/17 rear.

I spent some time trying to find the comment in Craig_D's thread and couldn't find it but I remember him talking about the feeling of hitting a big dip on the freeway where they were doing some paving. He was expecting a jarring hit and instead it was nothing. I would say that is the feeling I have now. The suspension is tight but compliant. Having full suspension travel makes an amazing difference.

The only thing left on the "to do" list is adjustable sway bars.

Bottom line -- "feel" is subjective. If you're considering making a change, try to find some locals who have different setups and go for a ride with them to see if you think you would be happy with it.

Thanks for your reply. The pictures of your car are beautiful. I wish I could say I got in on the Porsche party 5 years ago when SC's were only 15k. I acquired mine just about 1 year ago and paid substantially more for it. But I love it and at this point I am just trying to get it dialed in.

Did you do the suspension work yourself? Or did you take it to someone in your area?

[Bill Verburg]

Originally Posted by PorscheRally

Hi Bill,

This is great info for me.

Based on the above info, can we say that 17" wheels will never have the street ride comfort of the 16" wheels or any of the 15" tyre combinations?

The reason I am asking this question because I have 15"&16" wheels but the tyre selection/availability for these wheels getting very difficult over here in our market whereas 17" have a good selection. Although, I don't have 17" wheels in hand I am planning to buy some quality 17" wheels however I don't want to sacrife the street comfort ( mainly city driving and highways but also considering some rather poor surface back roads - broken asphalt with patholes etc )

Of course, I am aware of the fact that tires are the critical part of the equation but I am also prepared to equip my own car (1986 3.2 - may be 3.4 later on ) with the correct suspension bits. I have been reading the related topics but couldn't see much info with the suspension set up with the 2 or even 3 way adjustable shocks. I don't know, may be they are preferred more with the track day drivers and not much taken into consideration by the owners who is seeking for the most comfortable street cars.
For example, apparently KW came out with the so called variant 3 shocks for the G model cars which seemed very interesting. However, KW only has the low speed and rebound adjustability but not the Hi speed adjustability. That is pre-set. This made me think twice because, if I understand correct, we can get the best ride quality ( comfortable street driving with occasional canyon carving let's say ) with the professionally revalved digressed Blisteins and matching TBs, swaybars etc.
So, this is a bit confusing.
Shouldn't the 2/3 way ( especially the 3 way adjustability) be the best of the best when it comes to comfort setting if required.
I understand that normally, 2/3 way adjustable shocks mainly intended for the track and/or motorsport use but is not there any other KW like shocks which would give us a
comfortable but tight ( if needed or desired) modern day ride ?
Am I totally thinking in the wrong direction or is it just the matter of a budget for the project ?
Last but not least, for example, is there a way to have 17" wheels set up and still have a great comfort with the correct ingredients with the adjustable shocks and the matching components ? ( with the acceptance of the limits of the chasiss torsional flex which can not be changed on a road going car )
Regards
Kerem

Based on the above info, can we say that 17" wheels will never have the street ride comfort of the 16" wheels or any of the 15" tyre combinations?

I hate to make blanket statements, In general that's probably true, but there are many variables that can also come in to play.

for tires w/ the same OD
15s will have a taller sidewall than 17, this leads to a cushier ride because there is more flex
track tires will ride differently from a/s or hi perf street tires
new tires will ride better than old tires
run flats will ride worse than regulars

I know nothing about KWs, but in general most street shocks aren't adjustable while many race shocks are. Adjust-ability is a two edged sword, it's easier to adjust them wrong than right. all the modern race shocks I know about come w/ either a digressive or more esoteric valve scheme, that's most of the battle right there. I still like Bilstein as a very durable, reliable product, the only thing that needs to be altered is the stock linear valve stack, I don't understand why they haven't updated these, their newer products like PSS shocks are all digressive.