Suspension tune and handling journey

[literarymadness]

BDA:  I don't know if you have the same Spax as me, but I have the krypton gas ones from R&D which actually have 28 clicks. According to the brief two page manual from the Spax website, you adjust in increments of four.  Maybe the tech guy was thinking in terms of double click adjustments and that is why he said 14 levels.  I have my front set at 16 clicks. I have Protechs on the rear set halfway.  And thanks for posting that chart. 

[BDA]

I got mine back sometime in the later '90s and I don't think I have the documentation that came with them anymore (but maybe I should look through my papers because I wouldn't have thrown them away on purpose). I have emailed with SPAX tech support and he wasn't sure if I had the older shocks with 14 clicks or the more modern ones with 28. In case you don't remember from earlier in this thread, I have 250/130 springs. It sounds like your springs are similar.

[literarymadness]

BDA:  I just recently replaced my rear shocks and had them sent pre-loaded from Barry Spencer from Spencer Motor Sports.  Barry is a factory-trained Lotus Technician who worked in their engineering department. He is SCCA Solo 2 champion and he one it in a highly modified Europa.  He sets up any older model Lotus for racing.  I went for his Autocross suggestion of 150 lbs in the front and 120 lbs in the rear.  Paul (Pfreen) uses 250 lbs. in the front and loves them.  I lowered my rear to 6 inches.  My front is 5 1/2 inches.  It handles fairly neutral.  I think this thread you started has been one of the most useful for guys who want to really dial in their Europas.

[EuropaTC]

Well, that's very encouraging news and it sounds like there's more to come.  My dampers are relatively stiff with similar springs so if you are 11/24 & 9/24 (or 28 ?) then I'd bet there's a few more clicks to go before you start to become unhappy with the ride. 

I haven't had Spax dampers in a long while, in fact it probably dates back to the late 70s/early 80s so memory is definitely hazy but I do recall that adjusting the screws felt like there was no real resistance. I can also remember getting confused where I was with them, which probably explains why I've never had any since !

Great post on the chart. I haven't read that book, what's your overall opinion because from that chart it sounds like something I ought to get ?

Brian

[BDA]

Things are definitely going in the right direction.

You can do a search for "Carroll Smith" and see the books he's written. They are all still in print. I only have three of them and I have to admit that I have not taken nearly full advantage of the information in them (that's obvious by the fact that it took so long to get where I am with my car's handling!). They have a wealth of practical information but, of course, it is centered on race cars but there are lots of intersections with street cars.

Prepare To Win is about preparing a race car. It goes into topics as plumbing, basic metal work, welding, suspension bearings and bearing installations, suspension alignment, electrics, instruments, and fuel cells and more. It's a practical primer on putting together a race car so it discusses safety wiring, aircraft hardware, throttle linkages, etc. and even discusses records, paperwork, and organization.

Tune To Win was more about tuning what you built in Prepare To Win. There are chapters about the racing tires; weight, mas load and load transfer; suspension geometry; steering geometry; rates and rate control - springs and anti-roll bars; cooling; handling; and several other topics. The chapter that analyses suspension walks you through slip angles and their effects and goes into cutting out paper dolls (paper representations of the suspension) to graphically show you what happens at different roll scenarios. At some point, I plan to get more into that.

Nuts, Bolts, Fasteners, and Plumbing Handbook is really more than what it sounds like. In Prepare To Win, Smith discusses different aircraft bolt and nuts and when to use them, but in Nuts, Bolts, Fasteners... he is more analytical and discusses the characteristics of metal; stress, strain, load, and fatigue; thread physics; bolts and bolted joints; female threads; locking devices; washers; high performance plumbing; and more. There is stuff about different bolt and nut specs, information on some pretty fancy bolt/washer/nuts, failure analysis, threaded inserts... It's more analytical than his previous two books but there is some practical information. Interestingly, he says that he wanted to name this book Screw To Win but I think his publisher talked him out of it!

As I say he has other books that sound interesting to me and maybe to you too. He has a wealth of knowledge and his style is informal and easy to read. I wouldn't sell myself as any example, but I try to follow his general advice when I can. For example, I try to safety wire any bolt that does not have a lock nut on it (I readily admit that some are just too hard to get to so I fall short sometimes!), but I like aircraft bolts and I use them whenever possible. I was about to say it's overkill - and I guess the cost is - but I like the fact that they have a grip length meaning that the threaded portion is not in shear if sized correctly. They are made of steel that is similarly strong as a grade 5 bolt but because you don't have the extra stress risers and reduced diameters from all the threads in SAE bolts, they are actually stronger in practice.

If you're just interested in exploring the handling and analyzing your suspension (and it seems you've already done some work in that regard), I would advise Tune To Win. Prepare To Win is a great reference on building a car. The Nuts, Bolts, Fasteners... book is probably more information than a hobbyist car enthusiast would need.

[literarymadness]

BDA: Just ordered Tune to Win.  Gratitude for the info.  I am an information junkie.  His Engineering to Win has a Lotus Formula 1 on the cover.  Once again, this has been a tremendously insightful thread.

[EuropaTC]

Now that is what I call a book review, you ought to be on commission !

I don't think I'd go for the "Prepare" book because I'm not about to start building anything and I doubt that I'll need the high tech approach of "Nuts, Bolts, etc" but the "Tune to Win" sounds very much up my street.  I have a few books on suspension design and realise that they all cover the same basics but there's something about reading a different author which often gives me a slightly different or deeper understanding and always reinforces what I've already learnt.

That's something else on the "to buy" list....   

Brian

[surfguitar58]

If you're just interested in exploring the handling and analyzing your suspension (and it seems you've already done some work in that regard), I would advise Tune To Win. Prepare To Win is a great reference on building a car. The Nuts, Bolts, Fasteners... book is probably more information than a hobbyist car enthusiast would need.

Regarding the nuts, bolts and fasteners book, I have a question that is going to expose me as a total newbie at auto repair: When do you use Never-Seez/Copaslip type anti seize goop and when do you use Loctite type thread locker? I'm thinking mostly suspension components, since that is my next project, but also high and low temp engine components and basically everywhere. Does anti-sieze diminish the holding power of Ny-loc nuts? Would Loctite be unnecessarily redundant with Ny-loc nuts? The two products would seem to be at cross purposes to each other, but I want my parts to come apart easily in a few years, but I also don't want them to shake loose. Thoughts?
Tom

[EuropaTC]

Hi Tom,

It's always better to ask what you might think is a dumb question than to make an even dumber mistake !

Personally I don't use thread lock or even anti-seize compounds on nuts/bolts and I know that might be a controversial statement to make. Nothing wrong with either compound, I've just not considered it needed on my cars.  One thing that irks in my mind is how much (if any) an additional compound makes to the torque loading on a critical item. I know we did tests with dry bolts and various lubricants when I was working and some made a significant difference although it's probably down to the amount you use.

I use nylock nuts on either new or wire-brushed dry bolts and when tightened up correctly they've been fine. If it's something I consider very critical and where I know I won't see the assembly under normal conditions (like the front of the trailing arms) then I've added a split pin outside of the nylock, drilled after tightening.  Whenever I've checked the pin is still "loose" so ostensibly it's been a waste of time, but that bolt slackening off could easily go into toe out which you really don't want, so I feel happier with a pin there.

I do put grease or waxoyl (a waxy underseal) all over the final assembly and don't normally have problems undoing things later.

Brian

[BDA]

I don't think anti-seize will seriously degrade the nylon locking but I would expect that that it would diminish it a bit. Some people use anti-seize on every bolt and nut (IIRC, Certified is in that camp). I don't. It's not that it's not a good idea, but for a car kept in a garage and gets very limited exposure to rain, I don't think it's really necessary. That will ensure that the two won't get rusted together - something most people who wrench on old cars has cursed. Anti-seize is also very good to use on spark plugs in an aluminum head. One place I've used it recently is on the conical face of my lug nuts. I have conical lug nuts that mate with steel inserts in my wheels. When I was torquing them I felt the nut grab or drag against the insert which would give me a false torque reading. I did not put it on the threads. Torque values are usually assumed to be taken on dry fasteners, putting anti-seize on the threads and torquing to the same value would impart more tensile stress on the stud than a dry reading (part of any torque reading is the torque required to overcome the friction of the threads sliding against each other). For that reason, unless a wet torque spec is listed, I would not use anti-seize or other lubricant on a torqued fastener, but I would ensure the threads are clean.

It makes no sense to use loctite and anti-seize together. I use blue loctite when there is no other locking mechanism such as a lock nut or safety wire and I will want to be able to take that joint apart without a lot of drama. I know lock washers can work but Mr. Smith has convinced me not to rely on them unless I have no choice. I use red loctite on things I never want to come apart. It will require heat to undo red loctite. I think I read in Prepare To Win that there is actually a primer or a preparation product that is supposed to be used before using loctite, but I just use lacquer thinner when I'm motivated and a clean rag when I'm not. I advise using lacquer thinner, not the dry rag.

Prepare To Win is a good reference for things like this. Of course, he is writing for people wrenching on race cars so they don't normally have to contend with rust, but Mr. Smith explains a lot of assembly practices that are applicable to our situation. I probably should reread it.

[jbcollier]

If a bolt slides through a bore, you should use anti-seize on the shank of the bolt.  Especially if the bore is a dissimilar metal.  A good example would be the long bolts through the rear uprights. Also the upper pivot pin in the front suspension.

You should always use ant-seize with SS fasteners to prevent the threads from galling.  As an aside, never use ungraded SS fasteners as anything but ballast.

Thread locking compound only works on clean, dry threads do you can’t mix anti-seize and thread lockers.

Whether you should use anti-seize on “everything” depends on your local climate.  Wet climates result in significant corrosion issues while dry climates may have practically none.

[BDA]

I'm reviving this thread since I have continued to experiment (at a leisurely pace, unfortunately). Maybe everybody has gotten all they need or want from the thread up till now. I'll post this in case anybody might find it useful or entertaining.

If you go back to the beginning of this thread, you'll see my spring rates are F:250#/R:130# and that there was some question about how many adjustment steps my SPAX shocks had. One tech support guy I emailed wasn't sure if it was 14 or 28. Another said it was 14. Well, I got the front shocks up to 13 and still felt I had too much tendency for the car to try to swap ends (colorful term for oversteer), so I adjusted it another two clicks stiffer. It didn't feel any different going from 13 to 14 than from 14 to 15 so I'm guessing I have more adjustment than 14 clicks! I adjusted the fronts to 15 clicks. I had adjusted the rears up to 12 clicks because I theorized that what I felt was an oversteer might actually be a symptom of the same thing that causes the car to "wander" at highway speeds. This seemed to make it marginally worse in the turns so figuring that was caused by the greater roll resistance, I back down on the rear shocks to 9 clicks which was better.

Since the easiest adjustments I can make are shock adjustments and alignment (changing roll stiffness would require either different springs are fabricating and fitting a new anti-roll bar), I felt like I'd gotten pretty much at the end of my shock adjustments. I had a pair of 100# 13" springs lying around so I figured I'd replace my 130s with them. I raised the spring perches a half inch (I should have calculated it because to keep the same ride height in the rear required a 1.1" rise in the spring perches), and figuring the softer springs would allow softer shock settings, I went down another two clicks to 7. I expected this to have noticeable understeer but it didn't. I liked it better and thought I might like softer springs all around but until I got them, I would experiment with what I had.

The next iteration was to raise the rear spring perches another .6" (which should have put the rear ride height at about where it was before I changed the springs - I didn't measure it though) and check the camber. In spite of the fact that I hadn't fooled with it since the shop aligned the car, the camber was messed up. I set the camber to about -1.4°. It was a good improvement but occasionally, at about 80 mph, it would feel as though the car was being pushed around as though in a strong wind. Otherwise, it was pretty stable most places with a bit less of the feeling that the rear wants to swing around in a hard turn.

A couple of takeaways - first, writing this makes me realize that I'm really not attacking this in a very organized manner. For example, I should re-measure the important things before each test such as alignment. Second, I wasn't surprised that a 30# difference in the rear springs made a substantial difference but I was surprised that the balance (at least as I could feel it - and I wouldn't argue that my but is less sensitive than when I was young but then it might never have been very sensitive!) was not more screwed up. I know have F:250#/R:100# springs. I think Certified Lotus said that Dave Bean sold fast road springs that were F150#/R:115#. I'm anxious to try that. Third, it's interesting how there are such a wide range of setups depending on how people like it and I suspect how they drive. Driving around town with F:250#/R:130# was never a problem. It was firm but not jarring. With the shocks stiffened, it was pretty stable on the highway but I didn't feel it was neutral enough for my taste. I know others like that setup pretty well. I think I gave it a good chance of working. I had a very helpful conversation with JR73 awhile back and his rates seemed crazy to me. It expect he is a much better driver than I and that could be why he liked his setup. We're all different!

[BDA]

Thanks, Tom! I'm thinking mine are a bit more modern because when I got past 14 clicks, the 15th felt like the 14th, 13th, 12th, etc. In fact I found a note I made where I went to the 16th click. Also, I think I got mine in '90s. I took a closer look at my rear shocks and saw a number stamped on the shock so I thought I might call the SPAX folks and see if that number meant anything to them.

[Clifton]

I know have F:250#/R:100# springs. I think Certified Lotus said that Dave Bean sold fast road springs that were F150#/R:115#. I'm anxious to try that.

If you think you have oversteer with a 250 f / 130 r, you will definitely have oversteer softening the front that much. Are you testing oversteer limit on the street or track/autocross?

[BDA]

Well, that is a thought. I assume that Dave Bean or somebody there who knew has ass from a hole on a ground devised their suggested rates (F:150#/R:115#). It seems reasonable since they are both a similar multiple from the stock rates which I know to work pretty well. Of course my original rates (F:250#/R:130#) are also similar multiples of the stock rates and I wasn't able to get comfortable with them. I wish I had a lot more springs to try!

I haven't tried any autocrosses (I'm not sure I could get a helmet on but I ought to give it a try). I have a look I drive that has some S-type series of corners, a long sort of a sweeper on to a highway, some straight highway, and a rater tight exit off the highway. I think it can tell me what I want to know but there is traffic to deal with so it's not ideal.