FJCamper wrote: ↑Tue Sep 29, 2020 9:08 am
PS: We do run braided steel brake flex lines, no soft factory rubber.
This is a heck of a good discussion!
One of the reasons I don't use the braided lines is it is hard (no pun intended) to do a "squeeze check" to see if the internal material has hardened or swollen closed.
The swollen fuel and brake line problem is not a new problem and add to that, the long running soft lines (including the braided lines), after a period of of time, if the clamps are not close enough, you can get some "sag" which, if deep enough, can allow air pockets to form (pause and take a deep breath). Also (not usually in the soft transition use like the brake line join for suspension travel) the radius of braided line is minimal because of the braiding (again, stretching and compression of materials) but then rubber line can be bent too tight and the bend can collapse/pinch the line shut. One of the reasons I still rely on formed metal lines.
FJCamper wrote: ↑Mon Sep 28, 2020 4:30 pm
VW's and 356/911 Porsches were known for their light steering. That was because of large diameter steering wheels, narrow tires and light front ends. No power steering was considered necessary, until 1989 in the 964 which introduced 205 width tires.
Finally, under racing conditions, if you get the wider rear tire adhesion in proportion to the front tire adhesion, you can power through a fast corner without first going into over or understeer and correcting. On the street it will not matter, but racing it does.
So, long story short is, go as wide as possible front and rear so long as steering weight/other geometry is still acceptable and just tune suspension around the extra rear grip? With the realistic 150hp or so most of us will ever run in these cars do you not end up with a point of being massively overtired in the rear and get uncorrectable plough if you go, say, 175/55R16 front 225/45R17 rear like and early Elise
FJCamper wrote: ↑Mon Sep 28, 2020 4:30 pmAt one time, a quick steering adaptor was sold for Type 1 VW's that took a complete turn out of lock-to-lock steering. We had one back in our autocross days. It increased steering effort enough that small diameter aftermarket steering wheels were no fun on our Ghia. But how light is light and how heavy is heavy is subjective. Different drivers have different tolerances.
Curious question. Is there a reason no one has ever put out spindles with extended tierod arm attachment point (not sure what its actually called)? That would give you the quick steer while decreasing steering weight unlike the quicksteer kits that just extend the pitman arm. Plus if you do that just minorly and extend the pitman arm just a dash as well you should be able to keep all the geometry perfectly stock AFAIK. Is there something I'm missing here, or does it all just come down to tooling costs being too high?
FJCamper wrote: ↑Mon Sep 28, 2020 4:30 pmsingle 23.8mm on the Blitzwagen, modified with a front bias only pressure bias adjuster because of the 4-piston Wilwood calipers
Are you just using 4 pots on stock rotors?
Ol'fogasaurus wrote: ↑Mon Sep 28, 2020 9:24 pmQuestion: on the brakes, are you running a single chamber master cylinder or dual chamber unit and would it/did it make a difference? Just curious.
FJCamper wrote: ↑Tue Sep 29, 2020 9:08 am
We use a single 20.6mm master cylinder on the Ghia, and a single 23.8mm on the Blitzwagen
Is there any advantage at all to a single circuit system? I was under the impression the only functional difference between a single diameter dual circuit and single circuit system was the redundancy of the dual.
theKbStockpiler wrote: ↑Tue Sep 29, 2020 8:12 am
Besides for doing a test and seeing if the (width) of the tire is being overloaded with force, how do you tell if more width would be better or just a wast of rubber as in more friction, unsprung weight, steering resistance, etcetera ? A wider tire is not going to allow weight transfer to the outside of the car in a turn for example.
Not a direct answer to your question directly, but here is a great video on is wider is just better for track (side note, but this dudes channel is just awesome as a whole. He also has a great video on wheel diameter and talks a lot about subjective handling characteristics)
If you do a search on braided fuel lines you will get a wrong/incomplete answer as braided fuel lines go back to at least the Korean war and maybe back to WWII (not sure just when on this). I remember reading about them being on military equipment but not sure if it was in stuff like tanks, trucks or just aircraft.
I also remember seeing them on jet engine (I found a couple of good photos but can't down load them) but in short or complex runs among the hard lines but joining pieces of the engine together. I suspect that their flexibility was needed during the assy and/or maintence and yes, the fuel in jets were covered in the original designs of the braided lines. If I remember correctly there are or was Mil-spec coverage on them (I never looked them up when I had access to Mil-specs but since the fittings (you hear them referred to a AN fittings which AN is a misnomer as the are in different designs in several different Mil-specs and the AN needs more coding and drawing details do "describe" fittings) we use are covered in several different Mil specs. I assume that the line [as originally designed] are in there too). I spent a year and a half in "Power Plant and Strut" (the Pratt and Whitney engines) but did not deal with the engine itself but, again, heard a lot of detailed talk.
The guys started using braided line discovered them when they found the when in the military and they started showing up in show cars sometime in either in the late 50's or 60's. Anyway, like anything else there are good uses for them and bad uses for them but one can't think linearly about them either.
eskamobob1 Is there any advantage at all to a single circuit system? I was under the impression the only functional difference between a single diameter dual circuit and single circuit system was the redundancy of the dual.
From what little I have gotten into this in the past a lot of the load is to the front brakes as that is the direction you are usually heading (if this is what you are asking) with the rear brakes supporting. I seem to remember that at one time there was an adjuster you could use to balance the front and rear (in single circuit brake systems) needs but since I haven't seen or heard of it for a long time so I am not sure if they are available or street legal (in some states anyway). The dual chamber MC (one for the front and one for the rear brakes) was supposed to deal with the balance but that was for normal driving conditions.
With track racing, Auto-cross, drifting and other non-stock driving techniques (I intentionally left off off-road and sand) the balance might need to be adjusted but FJ knows more about that than I think I do. I got into it a bit in the 70's and the start of the 80s but got costed out of it quickly.
My description of the master cylinders we use was ambigious. By "single cylinder" I mean one dual circuit cylinder, as opposed to two single circuit cylinders as found on a bias-bar configuration.
And Fog, I am in complete agreement with custom-bent steel tube brake lines wherever possible. And for us, where it is not possible, braided steel hoses. Now, for street cars, I have no objection to rubber hoses. I like the way you can diagnose common brake problems just by touching the hose to feel pulsing or detect obstruction.
Now as to the notion that mfgs could make built-in quick steering by providing extra holes in the steering knuckles or pitman arm. I cannot think of any engineering reason they couldn't but there is probably such a low demand for that the mfg's just dismissed it.
And a closing comment on the general concept of wider rear ties being precise handling tuners, it depends on how identical the tire construction is. For instance, our Hoosier Speedster tires are bias ply. They havd more predictable breakaway than radials. So width differences as applied to bias ply construction as compared to radials would not be the same.
FJCamper wrote: ↑Tue Sep 29, 2020 1:55 pm
My description of the master cylinders we use was ambigious. By "single cylinder" I mean one dual circuit cylinder, as opposed to two single circuit cylinders as found on a bias-bar configuration.
And Fog, I am in complete agreement with custom-bent steel tube brake lines wherever possible. And for us, where it is not possible, braided steel hoses. Now, for street cars, I have no objection to rubber hoses. I like the way you can diagnose common brake problems just by touching the hose to feel pulsing or detect obstruction.
Now as to the notion that mfgs could make built-in quick steering by providing extra holes in the steering knuckles or pitman arm. I cannot think of any engineering reason they couldn't but there is probably such a low demand for that the mfg's just dismissed it.
And a closing comment on the general concept of wider rear ties being precise handling tuners, it depends on how identical the tire construction is. For instance, our Hoosier Speedster tires are bias ply. They havd more predictable breakaway than radials. So width differences as applied to bias ply construction as compared to radials would not be the same.
FJC
I am in complete agreement with custom-bent steel tube brake lines wherever possible.
I refer to the pictures I see of moving the brake lines under the car rather than (for bugs any way) having them on the floor by the tunnel. Even up the sides of the tunnel can get the sag. Again, I only recommend the rubber hoses for the hard line connections as there are too many potentially bad things that can happen (or not be traceable) with a tube with a wire cage around it.
Now as to the notion that mfg. could make built-in quick steering by providing extra holes in the steering knuckles or pitman arm. I cannot think of any engineering reason they couldn't but there is probably such a low demand for that the mfg. just dismissed it.
I can: the loading that goes into something like that requires a specific edge margin from any sides of the arm or other holes when reusing an existing part. Adding heat or even from drilling can take the temper out of the pitman arm's material. I also have seen the pitman arms lengthen and shortened which I am a bit nervous about especially when I see some of the welds . I have seen a lot of things in my life that makes my back side "pucker".
And a closing comment on the general concept of wider rear ties being precise handling tuners, it depends on how identical the tire construction is. For instance, our Hoosier Speedster tires are bias ply. They have more predictable breakaway than radials. So width differences as applied to bias ply construction as compared to radials would not be the same.
So true. And, you don't mix bias with radials as the sidewalls work differently to a certain extent. Seen the mix of tires tried before with not so good of an outcome. Trailers rarely use radials as bias ply tires work better especially under loads or so I have been told.
pics are worth a thousand words . For those that don't know how these work , there is a pivot ball that the threaded rod moves in the tube . turn the cable one way and it moves towards one push rod and away from the other , changing the mechanical force on the mastercylinders , like a see saw.
I've a good friend that builds front running Formula Vee race cars , I was able to adapt what they use . girling 11/16 master cylinders , I've just got stock from callipers (69 Ghia) and the usual aftermarket rear disc kit . I'll be up grading the rear to bigger brakes off a local ford falcon in the future . My car is heavier in the rear due to a 091 box and type 4 engine .
Wheel alignments and suspension set ups will change to suit different driver tastes . recent example of a formula vee. the original driver liked toe out on the front to help turn in and lower rear suspension (more neg camber) where as the new driver likes 0 toe and less neg camber . same car, very close lap times just different set ups .
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Back to tires. 1301-1303's , all have about 1 degree of camber either front or rear. So if the car is loaded the same as it is aligned while driven, the front tires should wear faster than the rears but wear evenly (flat). My thinking here is with an average beetle being driven on public roads would not benefit from being able to rotate the wheels from front to rear. When the fronts tread gets too shallow ,replace.
I disagree with some of this.
While it may be different with torsion bar suspension......with struts like super beetle and 411/412....having 205-55-15's on the front end are a LARGE step up from 195-60-15s. Yes...the front end of a 412 is light...lighter than a type 3 or bug even....but with proper air pressure and shock valving...and with proper re-adjustment for toe-in and camber the adhesion in cornering with the wider tire is far better.
Again...it may not help is much in a torsion bar set up....but 195 is not the limit. But I do feel you can go too far. I cannot see on a VW...the need for much over a 205 in the front.
The steering resistance change is typically the castor issue. Also...when going up in tread width....watch your profile to keep the total sidewall where you need it....but also be aware...that as you decrease side wall you reduce spring action and have to be able to compensate on shock valving. Ray
I read in another thread that because the front tire pressure is so low ,it makes the contact patch much larger.I did not think of this aspect at all. Does anyone go higher than 18psi for the front under any circumstances?
theKbStockpiler wrote: ↑Fri Oct 02, 2020 8:17 am
I read in another thread that because the front tire pressure is so low ,it makes the contact patch much larger.I did not think of this aspect at all. Does anyone go higher than 18psi for the front under any circumstances?
Yes, tire pressure does affect the tire contact patch with the ground but it also affects the sidewalls and how they work too (rolls, squat and leave it for example).
From another post I did today (but the text is edited slightly for more discussion):
"pictures of tire footprint due to tire pressure changes"
Do a search using this as a search text (I can't copy to edit the pix to a form that can be posted here) and look for one picture that is a cross-section of a tire. that clearly shows the high, normal and low pressure foot print/tread print.
One of the problems with the picture (there is one really good pix and it shows tires as the tread would sit with normal pressure, high pressure and low pressure but it doesn't show to contact effect caused by the side wall flex changing, not just because of the tire pressure changes, but it doesn't show the foot print as when turning or going around a corner where one side of the tire can be lifted slightly (or more) which also can affect the pattern you see in some of the pictures.
I found 18psi on the fronts for street use gave me pretty even wear across the tread. On my race set up I work to temperatures, for my R spec Dunlops 22 - 24 hot gave me a reasonably even temperature gradient across the tread. Though it was a bit higher on the outside due to cornering forces and alignment. The 22 - 24 hot was about 18 cold. I'd be interested to hear other peoples experience.
Circling back to the 195 vs 205 fronts, I think for street tyres you could definitely get the 205's to work as they should have good grip at all temperatures, but I think it is a moot point wether they will shorten stopping distances or improve cornering enough to warrant the work on clearance for turning, sorting wheel offset and steering weight. The 195 argument on the track is about getting enough heat into the tyre to stick even though I already use a soft compound. With more power and/or aero you could definitely get wider tyres to work (heat up) as we typically see on a Porsche.
Re the wear front versus back, it just depends how much rubber you lose every time you take off
intuitively I'm against not being able to rotate the tires but I have had cars that really did not need to have the tires change location to straighten up the wear. For the hell of it I gave the advice from AirCooled.net some honest thought that maybe having a staggered setup was not just a novelty and be worth it. I never paid that close of attention to my daily driver when I had one that was a acvw. I plan on making over 125 hp but I also don't want to have wide tires on the car that it does not need for cruising either. Judging from what's available , I think 185's in the front and 195's for the rear would fit my needs.
more important than say 10mm of tyre width , ie 185 or 195 , is the quality of the tyre itself . When I bought my Ghia it had directional Cooper tyres(205/50r16) , first time in the rain with the 2600cc fitted , I was merging onto a freeway , 4000rpm 3rd . put my foot down for a gap in the traffic and lost traction big time and was thankful I was on a straight bit of road .
I then fitted the AD08 Yokohama tyres on the rear. way higher wet and dry grip level . Now I have to be doing something intentional to spin the tyres . I'm guessing I'll get about 35,000km out of them ,which is great for a high performance tyre .
For the road I just run a mid price range tyre on the front , 195/55r16 . I don't push the car at stupid speeds around corners on the street so their grip is ok , also it's best to have less grip in the front than the rear . Under steer is easier to recover from and less dangerous than over steer .
. I have seen a lot of things in my life that makes my back side "pucker".
Does anyone go higher than 18psi for the front under any circumstances?