Thanks for being here. I'm sure this video won't be agreeable to all and that's okay. Tell me your experiences. I measure everything and prove to myself that what I think works actually does. Want to see where I get the force data for my recently purchased Bilsteins. Click this video below. Not many of you watched it because its pretty technical. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-8M2uUN5Psw4.html
Just something I learned 40 years ago. I replaced the Boge struts and shocks with gas KYB's. Wanted the stiffer ride so gas made sense. When I tore them down there was oil in the tube. I thought the old shocks were shot and the money spent was well worth it. My 72 T was lowered about 1.5 inches, being a light weight it rode terribly. Pogo and harsh. I talked to a old racer and he informed me that the oil was to dissipate heat from the insert to the shock housing to help the friction heat buildup transfer. Believe about 50 ml any viscosity. He also said majority of people want to use stiffer shocks to increase performance. He said the proper way was to adjust the spring rate for the track condition and shocks for road conditions, bumps, dips, rough and so forth. The shock adjustment was to control the speed of compressing and rebound. However, now we have damping systems like in =my Acura TLX SH AWD A spec that with computers and drive mode selection controls compression and rebound rates
I may be with you on this. I just did my 997 with the B6 package with stock springs and they are too stiff. I have PASM so when I need track mode I have access to that.
Tom very informative, if you have to take the struts apart again, you can wrap the top of the strut nut with Emory cloth , then put the pipe wrench on it won’t raze a sharp bur and it makes for a professional job . Working here on the east coast sometimes a pipe wrench and heat is needed .
Tom, I'm famous now...ha ha ha! Excellent video and content covering the shocks. I too like the Koni's and they were recommended by a few people before I started my project. Looking forward to going back and catching up on some of your missed videos. Hope you are doing well! -Shane
Great video. Wow, didn't realize how much disassembly is involved to change Porsche front shocks. The Jag is easier up front, but changing all four in the rear is a lot of work. Your new seat looks comfy. I must have missed that video.
Thanks Jeff. You are the first to mention the new seat. I haven't finished that video. The Sparcos are sold, so I had to sit on something! Stay tuned for details on the new seats. It wouldn't have been so bad if I didn't have to change the spindles. That was only because I changed brand.
I think you did the right thing going to softer shocks with no gas pressure. Now do this. I have discovered that a really easy and surprisingly effective way to significantly make the ride better in my cars is to, lower the tire pressure. In my 928 i find 28-30psi works good. in my 1940 Fargo/Canadian Dodge pick up I run 25 front and 22 rear (18 & 20 in. rims, super light truck) This truck was undriveable at 32 psi pressures. Just experiment with your car and see what happens. don't go to low or it won't handle good. I don't really care about tire wear since I only can put 2-3ooo km per year so the tires will last many years even at low pressure. Actually all 4 of my vehicles run on somewhat under inflated tires. When you have terrible roads in your area like me, you need to have a car drive nice or you won't drive it and get that enjoyment out of it; so that's what I have been doing for a few years now and So far it has become a pleasure to drive all of them again. Good luck
Great point. Tires heights and pressures do make a huge difference. I like 28psi cold on the front, but I hope to experiment more. The tires on Mac are 60 series so they can flex a lot which helps. I didn't like the 50 series that were on it before. Thanks for bringing this up.
Valuable review of your experience. Good follow up content for discussion on date of manufacture diffs and yet another for spindle alteration. Didn’t know about the Koni’s. Great context on functional aspects of suspension and relationship to damping rates and real world application. One thing porsche had going with original Bilsteins was earlier tire compliance and greater sidewall height. Would also be interested to hear what you think of the adjustable coil over options out there.
Thanks! Lots of stuff to continue on with and that is what this car is for; to experiment and share data/insights. It bothers me that not even the most basic data is available for shocks. There is also no disclosure of performance changes. I measured a digressive nature on the Bilsteins which contradicts others work from 10 years ago. When did that change happen? Why is one size fits all? I hope to get coilovers soon. KW is top of the line and fully adjustable. Big price tag! Might be worth it? Until then I'm pretty happy with the Konis. Stay tuned for more front suspension geometry changes and anti-roll bars!
@@GarageTimeAutoResto Clint can set you up with KWs, you’re probably aware. Ive seen Ohlins coilover solutions out there too, beyond inserts, something I’ve been exploring yet not convinced in value. That said, love the oem applications, interchangeability, modularity and after market support we’ve begun to find in classic Porsches. As you suggest, application factors in and damping science is great place to start. I love my current Bilstein coilover conversion (also Clint) though I’m running thicker profile TB15s. Handles well and soaks bumps extremely well, though I’m not clear on how much is damping vs tire compliance or spring rates. Starting where you are is the way to go. TY from all of us for amazing content.
I didn't even mention custom valving, but there is a lot of that out there too. I too am grateful for the options, but as they say buyer beware, ha ha.
Great info on the struts. I need to get some 3.5" struts for my build as I want to install "S" model calipers on my '72.... I used to have adjustable koni's on a 944 Turbo. They were adjustable with a white know at the top of the strut, where you did not have to remove them? Too bad you can't get those Koni's to make adjustment easier.
Good plan to use the 3.5" struts. Have you driven a 911 with early S brakes? They are little squishy in my opinion. I believe the yellow Konis are adjustable from the top. Nice feature but more stuff on compression.
Excellent, thanks. I'm working on a lightened C4 Corvette, and I expect to remove about 325 lbs total, including roughly 10 lbs (20%) of wheel and tire weight at each corner. I'm starting with the softer factory 'Base' suspension, but I may find that the car becomes quite stiff and jittery, having lost a bit more than 10% of its total weight along with the reduction in both un-sprung _and_ rotating weight of the wheels. The fresh KYB Gas-A-Adjust dampers currently on it do seem pretty well-judged for the stock setup, so maybe I won't have a problem. But if I do find it too harsh, I want to go with high-quality double-adjustable dampers. It appears that Koni offers only Yellows for my car, and I think those might also be too stiff for my taste. So, I may try QA1's double-adjustable shocks, which are currently $238 per corner. That's enough for me to proceed with caution, but they seem like well-made components. Just thought I'd share that source, in case anyone else is struggling to find a damper solution for an unusual combination.
Had a similair experience. With an alfa romeo, but a light rear wheel drive car nonetheless. Original shocks are not gas-pressure shocks. Bilstein B6 was way too rough. Koni Yellow was the move.
Bilstein is always super confusing. On my e46, the HD shocks had the same damping as the Sport, but were made for regular ride height springs whereas the Sport was made for lowered springs. So even in their naming across lines they aren't consistent if the Porsche HD vs Sport are actually different damping.
Good point. There's no telling what you're going to get. Someone else confirmed what you are saying. Apparently everyone gets the sport damping now with two different lengths. B6 and B8 (short). My recommendation is don't buy the new Bilsteins for an early light car as the title says.
The lighter the car, the softer the springs and dampening rates need to be. If using lower springs just check the shock has enough travel in compression and rebound. 1.5" in both directions would be nice if you can get it.
Man I have not heard such a display of misunderstanding about the how and why of a monotube gas shock function or the effect of the gas pressure in a long time.......the gas pressure chamber is so that there is NO air in the part holding the oil...When any shock/strut compresses there must be provision for the oil displaced by the rod, or shaft coming into the body..Your 40mm inverted Bilstein shaft is 10mm in diameter and approx 160mm long..it displaces that much oil..Many ordinary struts have 18mm or 20mm shafts about 160mm on many cars, 210 on that 88 Volvo a few feet away...The traditional way to allow for displacement of oil was to simply leave a space inside the shock with no oil..shaft comes into body, oil level risies...The valving, a stack of very thin steel shims sitting on the piston at the end of the rod deflect...the damping is an effect of the size and shape of the holes in the piston, the dia and thickness of the steel shims, and the oil viscosity... But conventional non-gas (the mono-tube, floating gas piston nitrogen charged shock was invented by Dr.F DeCarbon and patented in 1949 and Bilstein paid licence to begin manufactur in early 50s..Patent ran out in 1976, May or April...) shock are in essence like a butter churn..Cycle them and the oil aerates..Those holes and shims selected to meter oil at a given viscosity now are metering an emulsion of oil and air..and an emulsion full of air doesn't offer much resistance... Also your inability to compress the Bilstein with your hand and compress the Koni means nothing useful. Shocks move at and have a little more weight and force behind them when mounted on the car...MANY US based "experts" cycle shocks when testing on a machine at a speed of maybe2-3"/s...Bilstein's standard compression and rebound test speed is 0,52 m/s or 20.47 inche/second.. Like the speed in a sharp edged bump or a pot hole. Long in short is the insert is just valve too stiff on compression damping. But I think in time you will find the Konis will also be somewhat harsh on high shaft speed compression damping---like pot holes...Fine on bumps that look like sine-waves. They have been so on the old "Special D" red things from the 60s, for both cars and bikes and same to at least the early 90s when last I mounted some on a Saab 900 16v and was requested to remove them just 3 days later and mount up some second hand Bilsteins....which were fine, and customer once again happy.. Maybe you just got a duff pair.
Thanks for your long and thoughtful comment. I'm not making up a story about shock piston cavitation, it's real and is a function of gas pressure. Watch this video if you don't believe me. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-GBcRBOikb8c.html I never said the gas was or wasn't in a separate a chamber and maybe I should have. I'm also aware of shock speeds and have done my own testing at various speeds. 20in/sec is wicked fast and I couldn't get there driving my lightweight car. Watch this video, hand pressure is very relavant on a car that only ways 375lbs per corner. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-8M2uUN5Psw4.html My whole point of this video was to discuss how shocks behave on my lightweight 911. On a heavy Volvo Bilsteins are fine.
I bought some KYBs for my 912. They are terrible. Someone told me KYB meant “Kills Your Butt”. I haven’t tried Bilsteins on it. I have Bilsteins on my old defender- but obviously a much different kind of car overall- they seem great.
Kills your butt made me laugh 😂. I had some KYBs on an old El Camino that had a little bike valve that you could add air. Awesome when my jet ski was in the back. Glad you like Bilsteins on your defender. Like I said they are well suited for heavy stuff.
Great info thanks! I really needed to hear most of this video. I also have boge spindles and want to raise them. My car is also light, tho not nearly as light as yours. Have considered coil overs have you?
Thx, I'm open to coilovers and they are the natural progression as my driving improves. Right now I'm trying to learn the car without over building it if that makes any sense. Having said that, I already added gussets and stiffeners for future coilovers. I made these decisions before paint, while I was in there so to speak. Raising the spindles corrects a bunch of geometry when the car is lowered. Stay tuned.
good video and a ton of great points on suspension at the end. but dont think the bilsteins are all bad... not all b6's are valved the same. 1000 lakes spec b6's have half the rebound damping that the HD b6's do. i think there is a total of 4 or 5 different valving specs for the b6 damper. b8 has a different progression to its valving curve. koni classic is an emulsion shock so they tend to get overwhelmed/overheated easily with heavy use like rally but are great for the daily use.
I agree that Bilstein's aren't bad. I even said this in the video, but they aren't right for my lightweight car without serious work. Their mysterious part numbers and dampening data is frustrating.
@@GarageTimeAutoRestoi agree, the part numbers are a pain to sift thru. if it helps, the numbers they use for rebound/compression damping are one tenth of the pressure it takes to compress the damper (in Nm/s). seeing this thing at 1800 lbs, most off the shelf valving specs will feel over damped. performance shock may be able to revalve your old b6 for your current featherweight status. super helpful and informative fellas.
Why not put in the Sachs? They were also standard with the Boge strut casings....and cheaper than Koni..... Koni now has the yellow with in-car adjustable, using the supplied plastic turn handle. i'm changing mine (1985 Carrera), and trying to decide on Sachs or Koni in-car adjustable...Sachs don't adjust at all, but some people swear by them... Sachs about 130 or less, Koni 185.....
Professor, you are right on track.. No one wants a race car ride on the street. Hopefully, the spindle relocation will bring the sweet spot for the Koni's. If, I am correct, it will correct bump stop issues from being lower than stock?
Agree, I live in a very urban place that seems to always be under construction or the roads are just worn out! Can't enjoy a car that can't hit bumps. Raised spindles do a lot of things. Like you said, additional suspension travel, but it also helps with bump steer and roll center geometry. You may remember that I modelled the rear suspension in CAD to understand the turbo geometry and how the rear roll center can be adjusted. I added extra camber holes in the chassis. Will do the same analysis for the front. That will help understand the sweet spot that I'm talking about. The shock itself also has a sweet spot. Fun stuff!
At 8:10 you compress the shock, but there isn't a "Spring" to rebound the shock. That's not a good test. Suspension is very tricky on a car that has both low weight (due to a plethura of deletes) and no sound damping. That kind of vehicle is a track dedicated creation, not really for the street.
@@GarageTimeAutoRestoOf course they do not. However, you are comparing B6s to Konis; in which the Konis have "adjustable" dampening & the B6s do not. In this instance, if you had used the B8s - the shaft would have been shorter providing for a more appropriate travel (given the ride height of your vehicle). For a Street car, I would also recommend the Konis - as where the Bilstein's tend to be for heavier weighted vehicles.
Great video! So in your quest for more compliant/comfortable suspension, why not raise the ride height or consider a smaller torsion bar? I have a stock weight car, new Bilstein HDs, 17/21mm bars, and my first moves in winter will be to go back to stock bars and raise ride height, I think.
Thx. Are you saying you have a front 17mm torsion bar? Or is that your away bar size? If so where did you get it? I'm not opposed to raising ride height. My car currently is at 25.7" to the front fender lip. So it's not slammed by most standards. I can't remember what the stock European height is? Anyone here know? How long ago did you buy the Bilstein HD?
@@GarageTimeAutoResto the front torsion bars are 17mm, rears are 21mm. I bought nearly every part for my full suspension rebuild in October 2020 from Elephant Racing. I was going for the US ride height but ended up with the European by mistake.
My ride is a little bumpy, especially a lot of pitch forward and back over a lot of bumps, so I think I’m over-sprung. The cornering is excellent though, and it doesn’t bottom out like it did when every part in the poor thing was clapped out. I have the polybronze bushings, so there’s more thunk over each bump, but it articulates so nicely I’m hesitant to change back.
Are you going to do something to match the rear or close enough? Been club racing SCCA for over 20 years, a stiff body and compliant suspension seems to work better for me. Keep in mind that the tyre is an air spring and critical part of the suspension.
The rear feels close enough for now, but I'm not going to fine tune it until after the 6 cylinder engine goes in. Currently its a 4 cylinder which is much lighter. I'm envious of your track record, ha ha. Looking forward to more track time and since I'm a beginner I want to set the car up easy to drive. Which is soft tires, and compliant suspension. I'm not looking to eek out every .10 sec. I just want to have fun! I agree about the tire difference compliance. For example when I had the cookie cutter wheels and old 50 series tires the ride was even worse. Now, I have new 60 series tires and I like them much better. They squeel well before they break free and they are very predictable and easy to learn with. Thanks for your encouraging comment. I agree 100%
Appreciate your videos. Am about to do this on my 87, going with the red in front but note they don’t have a red for the rear. Thoughts on if I am best just going with the stock sachs in the rear, the yellow adjustable Koni, or something else?
I have an 87 too and the Bilsteins are fine in that car. It's all about the cars weight. I wouldn't mix and match front to rear unless you are great and adjusting and revalving
This was my fear when spec'ing the suspension for my light-ish weight hot-rod, so thank you for validating my Konis purchase 🙂 ... Like you, I have the RSR bushings up front (in the rear as well, that was quite a job) - but I got the top-adjustable Konis (yellow) and I'm running 21/31 torsion bars (anticipating track usage.) Yes, the instructions for the Konis are like hieroglyphics. Did you put any coolant in the Boge bodies before installing? Anyway, I only got a little bit of seat time in this arrangement before the car went onto a shipping container, but I can tell you it wasn't harsh at all with the dampers set to full soft. I know a lot of guys don't like dampers like this (complaining they never use the adjustment), but having previously had easily adjustable shocks in "fast" daily-driver, I know it is a godsend when you're driving some more sensitive passengers about! Great video as always!
Thanks, I didn't put any coolant down in the strut when I installed them. I'm curious to feel if they get warm at all during a normal long ride. Do your yellows have an adjustment on the top so you don't have to remove anything? I'm glad you like them so far.
@@GarageTimeAutoResto I'm not sure what the coolant is for, to be honest. I checked with some folks online (i.e. google search) and sure enough, that's what you're supposed to do! (50ml or so?) Also, thank you for demonstrating that the Konis don't return. I was not familiar with shocks like that and it gave me a bit of anxiety before installing them, thinking they might be faulty. The yellows (8641-1039Sport & 8210-1159Sport) are super easy to adjust with everything installed - they give you these little removable plastic knobs which you pop on the top and you simply twist them one way or another for firmness. The real test is when my car arrives in 3 months or so (fingers crossed) ... We moved from the relatively smooth roads of Australia to Europe, so we'll see if I made a mistake with my chosen setup!
Great explanation and application for the suspension concept. I also like the comments and discussion it generates. Will the sway bar set up stiffen the suspension feel if you hit a bump with only one wheel? Also new seats???
Thx and yes new seats! Will do another video on seats and why I swapped them. You are right about the sway bar adding stiffness. That's why I haven't put them on yet. I want to get one thing working right at a time. If only one wheel hits a bump then it will certainly add to the suspension stiffness. BTW, all the aftermarket bars are too stiff. So what should I do?
It was more of a question since my understanding of the suspension physics is really basic. This is why I appreciate your explanation on the topic. Maybe an Ajustable sway bar set up like the RSR has? My 68 911 was a race car and it came with it. Haven’t tested it yet but I like the ajustability.
Have you considered GAZ inserts? Although it's apples to oranges, I'm building a VW Super Beetle for autocross which would be a similar concept. I don't have GAZ, build like the idea
I haven't, but I'm open to it. I wish the manufactures would share the performance data. That would save a lot of money and grief of just trying stuff. I'll call them and see if they want to collaborate.
Awesome! For right now I'm extremely happy with this installment. I'm lost In the woods on my car, I think it has the stock damperd, don't know for sure though. I lowered it... and with the rack spacers and shorter tires the ride is awful... bump steers too. It's not modded to be lite I'm a 260 #'r.. Any suggestions? I'd like it a little lower than stock with the correct rubber but have no clue where to start.
How low did you go? My car is 25.7" to the fender lip and the control arms point down slightly. Maybe 5 deg. If yours are pointing up, then you need to correct it. First confirm what torsion bar size you have. 18.8mm is stock and the lightest available. Then confirm that you aren't bottomed out on the bump rubbers. Check out this video on how to do that. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-R9wu0NZYK0E.html Also make sure nothing is bent or binding. You may need to raise the spindle heights to restore the factory geometry if you want your car low. That means cutting off the spindles and welding them higher up on the strut tube. If you do all the above you'll have a great driving car. Bump steer is not good. Raised spindles will help with that too.
No. It's not about which brand is better. It's about application. Bilstein makes an incredible product, just not specifically for this application. Or perhaps not within the confines of the budget 😉 I installed Bilstein yellows on my MK6 Jetta GLI and it was night and day difference over the factory configuration. Cadillac smooth, but also firm and tight when it matters. But on say a MINI, you will run into a similar problem as this Porsche. The same yellows are Uber harsh, and you get significant wheelhop. On MINI's Koni, or Sachs are the best way to go. Simply because both of those brands have factory equivalent replacements, better suited for the daily grind.
That's what I'm saying. The stuff you buy today isn't the same stuff. Sure you can send new struts back to them and ask for them to be re-valved, but to what spec? Such a pity that all the data is secret. .
@@GarageTimeAutoResto At the same time we bought the RSR parts from the factory. I think they wre bought from Porsche's racing department when Porsche was building the 2.8 RSR's
