Lowering: Opinions on H+R springs/HD Bilstein shock setup
01-14-2003, 11:09 AM
#31
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Nol,
I called the bilstein customer support number on their website for most of the information I got.
There *IS* a review of the Bilstein HD + H&R springs Gert sells in the archives:
<a href="http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic;f=3;t=006005#000000" target="_blank">Review of Bilstein HD + H&R springs</a>
happy shopping....
sean
I called the bilstein customer support number on their website for most of the information I got.
There *IS* a review of the Bilstein HD + H&R springs Gert sells in the archives:
<a href="http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic;f=3;t=006005#000000" target="_blank">Review of Bilstein HD + H&R springs</a>
happy shopping....
sean
01-14-2003, 12:53 PM
#32
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</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Christer:
<strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Danny, my car is 'in the shop' as I speak getting Gerts H&R coilovers with RS sways front and rear installed (amongst other things). Glad to hear yet ANOTHER happy customer on full coilovers. They are not that cheap but from what I have heard absolutely excellent!</strong>[/QUOTE]
Yes they are Christer. I really cannot say enough about them! I used to own front engine P-Cars and I used to love how neutral my 968 was. Very forgiving and balanced so I was horrified with the stock 993 on the track. The H&R setup reminds me exactly how the 968 was. Well balanced, neutral and forgiving.
As a matter of fact on my new race car project I'm going to trust again H&R and try their new RSS Club Racing coilover kit...Hopefully my deal is going to go through shortly and I will be reporting on this suspension by mid February.
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
<strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Danny, my car is 'in the shop' as I speak getting Gerts H&R coilovers with RS sways front and rear installed (amongst other things). Glad to hear yet ANOTHER happy customer on full coilovers. They are not that cheap but from what I have heard absolutely excellent!</strong>[/QUOTE]
Yes they are Christer. I really cannot say enough about them! I used to own front engine P-Cars and I used to love how neutral my 968 was. Very forgiving and balanced so I was horrified with the stock 993 on the track. The H&R setup reminds me exactly how the 968 was. Well balanced, neutral and forgiving.
As a matter of fact on my new race car project I'm going to trust again H&R and try their new RSS Club Racing coilover kit...Hopefully my deal is going to go through shortly and I will be reporting on this suspension by mid February.
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
01-14-2003, 04:55 PM
#34
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Sean, Thanks <img border="0" alt="[thumbsup]" title="" src="graemlins/bigok.gif" /> ! I remember reading that thread but it was before I was aware of the package sold by Gert, I never connected the two. Gert's site still doesn't mention any spring rates on the H&R-HD kit, but he does for the H&R coilovers. I found some H&R spring rates in the archives as FR 240-260 RR 280-310.
DC, It is reported earlier in this thread the HD's are valved to match the M030 ride. In that case I would think they are not optimal for the RS springs. The RS is lower and stiffer still compared to M030, just my 0.02$.
I've posted before and repeat here that spring rates given for different coilover sets indicate different approaches to setting up the 993:
H&R coilovers : FR 290-310 RR 350-370
Bilstein PSS-9: FR 225-250 RR 400-685
Note how the front to rear spring rate difference is much higher for the PSS-9 and how the front rate is relatively soft with a very stiff rear. These differences should show up when driving cars with these two systems IMHO. Also, I wonder if the Bilstein HD's are valved consistent with the PSS-9 approach, i.e. for a softer FR and stiffer RR.
If I recall correctly the H&R set-up is more akin the factory M030, but it uses all progressive springs where M030 has progressive springs front only. The progression does not appear to be that strong though at 20 lbs/in (or am I missing something?).
Enjoy <img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />
Nol
DC, It is reported earlier in this thread the HD's are valved to match the M030 ride. In that case I would think they are not optimal for the RS springs. The RS is lower and stiffer still compared to M030, just my 0.02$.
I've posted before and repeat here that spring rates given for different coilover sets indicate different approaches to setting up the 993:
H&R coilovers : FR 290-310 RR 350-370
Bilstein PSS-9: FR 225-250 RR 400-685
Note how the front to rear spring rate difference is much higher for the PSS-9 and how the front rate is relatively soft with a very stiff rear. These differences should show up when driving cars with these two systems IMHO. Also, I wonder if the Bilstein HD's are valved consistent with the PSS-9 approach, i.e. for a softer FR and stiffer RR.
If I recall correctly the H&R set-up is more akin the factory M030, but it uses all progressive springs where M030 has progressive springs front only. The progression does not appear to be that strong though at 20 lbs/in (or am I missing something?).
Enjoy <img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />
Nol
01-14-2003, 10:24 PM
#36
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I probably will never see track, have been thinking of HD+M030 Row spring+sway bars and am just waiting for the right time ($$$) to pull the trigger. Let me see if I can get this straight : This kit has no problem with fitments as long as it's installed with US stock height. With Row height, the rear shocks are a little too long? I really don't mind a little lower like the row height (1" front and 3/4" rear).
Any comment on HD with Us Stock spring/sways? What is the predicted result?
Thx
Any comment on HD with Us Stock spring/sways? What is the predicted result?
Thx
01-14-2003, 11:04 PM
#37
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hn,
The predicted result with the US spring/sways M032 or M030 should be very good - however, I don't know of anyone who has done the replacement this way. Although I don't have exact numbers, the folks I talked to at Bilstein told me that the HDs had been valved for the M030 springs, but that they were perfectly compatible with the M032 setup.
Nol,
The missing component is the progression rate - eg. the change in lbs/in per inch (eg lbs/in*in). I believe, based on the little bit of research I did last week, that the H&Rs have a lower rate of change of spring rate, hence the smaller variation in the top & bottom rates. Incidentally, I think this is one of the reasons why the damping level changes on the shocks of the PSS-9 system are so effective at changing the characteristics of the suspension "stiffness"
As far as the design of the progressive springs themselves, the PSS-9 is a clearly superior design. It uses 2 springs of different rates instead of a progressively wound coil, the latter of which typically results in a much more highly non-linear composite spring rate. Meaning you get a rate of change of rate of change of rate of change (ad infinitum) I can give a more mathy explaination - if people are truely interested, here's what I wrote on 3/27/2002 - to which EJ simply replied: huh?
"Let me try and explain what an inversely progressive spring is, and how it might be constructed). First recall that the spring law (also known as Hooke's Law) states:
Fspring = -K * x
This means that the force a spring exerts is proportional to both the spring rate (k) and the distance of spring travel. In reality this is just an approximation which works well for springs constructed in equal diameter coils out of a consistant material. However, it is possible to construct a spring where the force law is quite different, perhaps becoming proportional to the square of the spring travel, for example...
In the case of an inversly progressive (or simply progressive) spring, the spring rate, k is not constant, but changes with the spring travel:
K = A*x + B (progressive)
K = -A*x + B (inversly progressive)
Where B is the spring rate at 0 travel, and A is the slope (or "progressiveness") of the spting rate. In the case of an inversely progressive spring, A is negative, so that with increasing spring travel, the spring rate is reduced. Plug this into our linear spring equation above, and we get:
Fspring = (A*x + B) * x (progressive)
= A*x^2 + B*x
Fspring = (-A*x + B) * x (inversely progressive)
= -A*x^2 + B*x
So...how does one build a spring with a spring rate that is proportional to spring travel ?? The easiest way is to vary the spacing of the coils, for example compare a linear spring:
< lost picture of a constant coil spring >
To a progressive spring:
< lost picture of a H&R or M030 front type spring >
If you look at the picture, you will notice that the coils are wound non-uniformly with the progressive spring. You can imagine how with the progressive spring the spring rate will increase as the force F is applied and the spring travel increases in the x-direction.
An inversely progressive spring is similar in construction, except that the loosely wound coils are constructed with a material that is less complient or non-complient up to a certain applied load. Thus, this portion of the spring doesn't compress at all until a certain threshold is overcome, and the loose winds then bring the overall spring rate down"
Does that answer the question - Probably just more confusing eh. Grin.
sean
The predicted result with the US spring/sways M032 or M030 should be very good - however, I don't know of anyone who has done the replacement this way. Although I don't have exact numbers, the folks I talked to at Bilstein told me that the HDs had been valved for the M030 springs, but that they were perfectly compatible with the M032 setup.
Nol,
The missing component is the progression rate - eg. the change in lbs/in per inch (eg lbs/in*in). I believe, based on the little bit of research I did last week, that the H&Rs have a lower rate of change of spring rate, hence the smaller variation in the top & bottom rates. Incidentally, I think this is one of the reasons why the damping level changes on the shocks of the PSS-9 system are so effective at changing the characteristics of the suspension "stiffness"
As far as the design of the progressive springs themselves, the PSS-9 is a clearly superior design. It uses 2 springs of different rates instead of a progressively wound coil, the latter of which typically results in a much more highly non-linear composite spring rate. Meaning you get a rate of change of rate of change of rate of change (ad infinitum) I can give a more mathy explaination - if people are truely interested, here's what I wrote on 3/27/2002 - to which EJ simply replied: huh?
"Let me try and explain what an inversely progressive spring is, and how it might be constructed). First recall that the spring law (also known as Hooke's Law) states:
Fspring = -K * x
This means that the force a spring exerts is proportional to both the spring rate (k) and the distance of spring travel. In reality this is just an approximation which works well for springs constructed in equal diameter coils out of a consistant material. However, it is possible to construct a spring where the force law is quite different, perhaps becoming proportional to the square of the spring travel, for example...
In the case of an inversly progressive (or simply progressive) spring, the spring rate, k is not constant, but changes with the spring travel:
K = A*x + B (progressive)
K = -A*x + B (inversly progressive)
Where B is the spring rate at 0 travel, and A is the slope (or "progressiveness") of the spting rate. In the case of an inversely progressive spring, A is negative, so that with increasing spring travel, the spring rate is reduced. Plug this into our linear spring equation above, and we get:
Fspring = (A*x + B) * x (progressive)
= A*x^2 + B*x
Fspring = (-A*x + B) * x (inversely progressive)
= -A*x^2 + B*x
So...how does one build a spring with a spring rate that is proportional to spring travel ?? The easiest way is to vary the spacing of the coils, for example compare a linear spring:
< lost picture of a constant coil spring >
To a progressive spring:
< lost picture of a H&R or M030 front type spring >
If you look at the picture, you will notice that the coils are wound non-uniformly with the progressive spring. You can imagine how with the progressive spring the spring rate will increase as the force F is applied and the spring travel increases in the x-direction.
An inversely progressive spring is similar in construction, except that the loosely wound coils are constructed with a material that is less complient or non-complient up to a certain applied load. Thus, this portion of the spring doesn't compress at all until a certain threshold is overcome, and the loose winds then bring the overall spring rate down"
Does that answer the question - Probably just more confusing eh. Grin.
sean
01-14-2003, 11:39 PM
#39
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Someone said that hte Bilstein HD are "too long" for the ROW M030 springs and ok for the US M030.
Shouldn't there be a Bilstein HD sold in Europe that is optimal for the ROW M030 springs? Difference from the Bilstein HD part # for the US M030 springs.
Shouldn't there be a Bilstein HD sold in Europe that is optimal for the ROW M030 springs? Difference from the Bilstein HD part # for the US M030 springs.
01-14-2003, 11:40 PM
#40
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</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by DJF1:
Like I said previously I have the H&R COILOVER kit, not to be confused with the H&R and HD combo.
This system is PSS-9 like without the adjustability of the PSS-9.I did not need the adjustability either. I paired it with the M030 sways and IMO it was the best money ever spend! Stiffer than the M030 setup, closer to the RS spec, no fitment problems with sways or perches and lowers the car to RS spec if you wish without a problem. The shocks for this kit are made by bilstein but valved to H&R specs to precicely match the springs. The car is transformed on or off the track. Cornering is flat and the car is very balanced.
It really amazes me how this kit is never in someones options! It is an incredible upgrade if you dont mind the stiffness associated with an RS style upgrade and have track work in mind...[/QB]</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">I agree completely with DFJ1, as I have the same set-up: H&R coilovers with RoW M030 sway bars 22mm front and 21 mm rear (from the Turbo). I have been very happy with this set-up. It fit perfectly-I know this because I did it myself in my garage over a weekend. No monoballs, extra drop links, etc required. Best of all, good bye understeer!
Jason
Like I said previously I have the H&R COILOVER kit, not to be confused with the H&R and HD combo.
This system is PSS-9 like without the adjustability of the PSS-9.I did not need the adjustability either. I paired it with the M030 sways and IMO it was the best money ever spend! Stiffer than the M030 setup, closer to the RS spec, no fitment problems with sways or perches and lowers the car to RS spec if you wish without a problem. The shocks for this kit are made by bilstein but valved to H&R specs to precicely match the springs. The car is transformed on or off the track. Cornering is flat and the car is very balanced.
It really amazes me how this kit is never in someones options! It is an incredible upgrade if you dont mind the stiffness associated with an RS style upgrade and have track work in mind...[/QB]</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">I agree completely with DFJ1, as I have the same set-up: H&R coilovers with RoW M030 sway bars 22mm front and 21 mm rear (from the Turbo). I have been very happy with this set-up. It fit perfectly-I know this because I did it myself in my garage over a weekend. No monoballs, extra drop links, etc required. Best of all, good bye understeer!
Jason
01-15-2003, 01:00 AM
#41
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Damn Sean! Reading your post I felt like I was back in school trying to figure out what my Physics teacher was trying to say! <img border="0" alt="[ouch]" title="" src="graemlins/c.gif" />
01-15-2003, 05:13 AM
#42
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Sean,
that explains why my progressive springs (H&R) feel inconsistent - car will do a double set when cornering. From what you've said, sounds like the PSS-9 coilovers with tender springs (inversely progressive) is the way to go.
that explains why my progressive springs (H&R) feel inconsistent - car will do a double set when cornering. From what you've said, sounds like the PSS-9 coilovers with tender springs (inversely progressive) is the way to go.
01-15-2003, 11:00 AM
#43
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MetalSolid -
I doubt your H&R springs are truely "inversely progressive" as I describe above. Such springs are very expensive to produce, requiring exotic multi-phase materials. On top of that, they would be a lousy choice for an auto suspension for the simple fact that they give LESS resistance the further they are compressed (up to a certain limit of course). This would give really bizzare handling. I am not aware of any true "inversely progressive" springs on the market for automobiles. If you can point me to an example, I would be very interested.
I am almost certain that what you describe as a "double set" is due to worn shocks. Here's why:
The shocks in any suspension are the damping elements, and as such yeild a resistive force that is proportional (at least) to the rate of change in their length. This means that the faster you try and compress a shock, the more resistance it offers. A worn shock will typically offer nearly the same resistance as new when compressed fast, but *FAR* less when compressed slowly.
In a turn, the initial turn-in will be damped at a much higher rate than once the susepension is "set" in the turn. At this point, a worn shock will offer far less resisitance, and the suspension will "reset" to the new lower resistance. Thus, a "double set".
Coincidently, I've seen marketeers (No offense to Mike in Chi
) use the therm "inversely progressive" to describe regular progressive springs for 2 reasons: 1) the negative sign in front of the spring rate in Hooke's Law, and 2) because the spings taper from large to small coils "inversely" (from top to bottom). This just makes us engineers cringe. Grin.
All of this discussion has given me motivation to write a comprehensive Spring-Mass-Damper FAQ as it relates to our suspension systems. It would be fairly mathy - but I think I could explain most things with good diagrams and "laymen's terms". Would people be interested ?
sean
I doubt your H&R springs are truely "inversely progressive" as I describe above. Such springs are very expensive to produce, requiring exotic multi-phase materials. On top of that, they would be a lousy choice for an auto suspension for the simple fact that they give LESS resistance the further they are compressed (up to a certain limit of course). This would give really bizzare handling. I am not aware of any true "inversely progressive" springs on the market for automobiles. If you can point me to an example, I would be very interested.
I am almost certain that what you describe as a "double set" is due to worn shocks. Here's why:
The shocks in any suspension are the damping elements, and as such yeild a resistive force that is proportional (at least) to the rate of change in their length. This means that the faster you try and compress a shock, the more resistance it offers. A worn shock will typically offer nearly the same resistance as new when compressed fast, but *FAR* less when compressed slowly.
In a turn, the initial turn-in will be damped at a much higher rate than once the susepension is "set" in the turn. At this point, a worn shock will offer far less resisitance, and the suspension will "reset" to the new lower resistance. Thus, a "double set".
Coincidently, I've seen marketeers (No offense to Mike in Chi
) use the therm "inversely progressive" to describe regular progressive springs for 2 reasons: 1) the negative sign in front of the spring rate in Hooke's Law, and 2) because the spings taper from large to small coils "inversely" (from top to bottom). This just makes us engineers cringe. Grin. All of this discussion has given me motivation to write a comprehensive Spring-Mass-Damper FAQ as it relates to our suspension systems. It would be fairly mathy - but I think I could explain most things with good diagrams and "laymen's terms". Would people be interested ?
sean
01-15-2003, 03:22 PM
#44
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Thx Sean for the reply.
</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Bill 993:
<strong>Someone said that hte Bilstein HD are "too long" for the ROW M030 springs and ok for the US M030.
Shouldn't there be a Bilstein HD sold in Europe that is optimal for the ROW M030 springs? Difference from the Bilstein HD part # for the US M030 springs.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Exactly! Straight forward installed ROW set up/height with life time warranty on shocks <img border="0" alt="[jumper]" title="" src="graemlins/jumper.gif" />
</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Bill 993:
<strong>Someone said that hte Bilstein HD are "too long" for the ROW M030 springs and ok for the US M030.
Shouldn't there be a Bilstein HD sold in Europe that is optimal for the ROW M030 springs? Difference from the Bilstein HD part # for the US M030 springs.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Exactly! Straight forward installed ROW set up/height with life time warranty on shocks <img border="0" alt="[jumper]" title="" src="graemlins/jumper.gif" />
01-15-2003, 04:45 PM
#45
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</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Sean Spicer:
<strong>I am almost certain that what you describe as a "double set" is due to worn shocks. Here's why:
{snip}
All of this discussion has given me motivation to write a comprehensive Spring-Mass-Damper FAQ as it relates to our suspension systems. It would be fairly mathy - but I think I could explain most things with good diagrams and "laymen's terms". Would people be interested ?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Sean, the explanation of why worn shocks produce the 'double set' was the key point of interest for me -- thanks!
<strong>I am almost certain that what you describe as a "double set" is due to worn shocks. Here's why:
{snip}
All of this discussion has given me motivation to write a comprehensive Spring-Mass-Damper FAQ as it relates to our suspension systems. It would be fairly mathy - but I think I could explain most things with good diagrams and "laymen's terms". Would people be interested ?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Sean, the explanation of why worn shocks produce the 'double set' was the key point of interest for me -- thanks!