GTI project

[zracre]

I bought this thing for $200...I would like to make it into a rallycross car with some friends on a super cheap budget...anyone have any stock pieces laying around? we are gutting it and putting stock springs back on it.

[Bill Miller]

What all are you looking for Evan? I've got an A2 16v Jetta that's been picked pretty clean, but may still have a few things left. I definately have some stock front springs.

[zracre]

I could use them! Im going to put on some new struts but would like stock height springs...I will also make some skid plates. I know the shift linkage is a mess so any bits that are common in there that are laying around...also any suggestions to make it a better rally car...

[Bill Miller]

No problem, I can hook you up w/ the front springs. I've also got a compelte A2 shift linkage rebuild kit. It has every part that you can replace in the shift linkage. I've also got the rear springs, but I don't want to take the back end apart, as it makes it hard to move the shell around. Somebody did want some of the rear brake stuff (calipers are gone), so if he wants the axle, I can probably hook you up w/ the rear springs. LMK

[Conover]

I think you need a happy bar on that thing!

Super cheap rear sway bar!

24"-26"x3" of steel plate 3/16" works good, welded to the front(open) side of the rear axle beam, makes a great super cheap rear sway bar, you can get the steel at Lowes, the welding is up to you. I put ont on my $160 A2 Gti 8v and it's great in combo with the Shine springs, and the ABA that car is wicked fun! I think I've got less than 1k in it too, that's the best part!

Kirk Calls it the Johnny Cash car. . ."one piece at a time, and it didn't even cost me a dime. . . ."

[Bildon]

I second Cameron's sway bar idea. But if you want to go even cheaper... get some thick U-bolts and a peice of (3" I think) square thick walled tubing and bolt her in there. Cheap ugly and effective.

Here's a pic of the C. Miller Wolrd Challenge VWMS Jetta that I was crewing for a couple weeks back. Notice the rear bar was completly welded closed.
http://www.bildon.com/pub/MidoHio/images/Races%20067.jpg

[Conover]

I notice that they also have replaced the factory "sway Bar" with an adjustable one, hmm. ..

[Knestis]

That seems awfully obvious, in hindsight. Hmm.
K

[Conover]

That seems awfully obvious, in hindsight. Hmm.
K
[/b]
Well, we have another rear beam in the shop, let's get to it!

[wclark]

I think you need a happy bar on that thing!

Super cheap rear sway bar!

24"-26"x3" of steel plate 3/16" works good, welded to the front(open) side of the rear axle beam, makes a great super cheap rear sway bar, you can get the steel at Lowes, the welding is up to you. I put ont on my $160 A2 Gti 8v and it's great in combo with the Shine springs, and the ABA that car is wicked fun! I think I've got less than 1k in it too, that's the best part!

Kirk Calls it the Johnny Cash car. . ."one piece at a time, and it didn't even cost me a dime. . . ."
[/b]

I am converting my rally A2 GTI to a hillclimber. These paved mountain roads in Vermont arent as smooth as most road race circuits so the spring rates need to be a notch lower to keep the car settled. I have been running my gravel setup, except for a shorter firmer spring since I startd hillclimbing acouple seasons ago. This is 10" 300F/200R coilovers, no front bar and the stock GTI rear (bar). Balance is pretty good but body lean is excessive making my contact patch a little outside edge heavy even with a lot of camber. I am probably getting too much weight transfer onto the rear off the starting line too. I think I want to move the front springs to the rear, get a set of 400 for the front, put the stock front bar back in and add a rear bar. I dont want to go much firmer than those springs because the uneveness of the pavement.

I like the above idea of the welded in plate for the rear sway bar and have one on hand. My question is, anyone have any idea what the "wheel rate" of an axle beam configured this way turns out to be? I know the sway bar isnt the same as a spring, but I cant think of a better term to describe its effect on a single wheel - for comparison between bars.

Thanks,
Walter

[wclark]

I welded in the 3" x 3/16" plate. Mine is about 26" long.

Before doing so I used my scales to measure the "rate" of the stock rear beam and then measured it the same way after welding in the plate. The set-up I used to measure it was to remove the lower bolts from the shocks and swing them out of the way so the shocks and springs dont add anything. I braced one end of the beam at the left wheel with a 2x4 that rested on the axle behind the spindle on the bottom and on the shock tower at the top. Then I lowered the car onto the scales until the weight of the beam and tires were on the right rear scale and the 2x4 was just contacting at both ends. I lowered the car 1" then 2" and observed the scale. I subtracted the first weight from the second 2 measurements to get a "pounds/inch of deflection" value.

Before adding the plate I measured 80 pounds per inch. After I TIG welded the plate in place I measured 240 pounds per inch.

The 80 pounds is about half what I would have expected based on what Per Schroeder listed he calculated in his Volkswagen Sport Tuning book and I have not been able to find out why, but I suspect it has something to do with measuring the deflection end-to-end versus some sort of middle-to-end calculation. To decide if I has some sort of fatigued axle beam or just a different value I measured a second GTI beam I have as a spare. The technique was slightly different since this one wasnt installed but I came up with the same 80 pounds per inch.

If my theory about why my values are different than what Per listed are correct then the plate does about the same thing as he indicated a 25mm solid bar does (about 500 pounds/inch).

It should be interesting to see if ordinary mild steel, like this plate, welded to whatever the beam is made from measures the same after a season of hillclimbs.

It would also be interesting to see what others have measured for the "wheel rate" of other anti-sway setups, but I am not holding my breath. Seems everyone just slaps something together, declares it awsome and goes driving. I started compiling a spreadsheet of spring rates and (as best I could) swaybars that others say they are using with success, and I used some formulas to relate them to each other within each vehicle to produce a single number to compare one setup to another I looked for some common "truth" around spring and sway ratios for the A2. What I found was anything but common wisdom (other than agreement that stiffer springs and firmer rear bar are good) which surprised me considering these have been around and have been raced for at least 20 years. I know people have preferences based on driving style but the variation in the relationships of springs and swaybars (between and among) amazed me.

[Knestis]

... Seems everyone just slaps something together, declares it awsome and goes driving. ...
[/b]
...or in my case, I take more understeer out of the car by whatever means are handy at the time, think it's all loosey-goosey, then get used to it in three weekends and want more. Lather, rinse, repeat. :)

(We haven't resorted to toe on the rear end because we primarily do enduros and want the car to roll as easy as possible for efficiency.)

If you are looking for Truth with a capital T, you're in for a long search but your test was pretty elegant and data - even John Deere data - is valuable. Thanks for posting this.

K

[Eric Parham]

If you are looking for Truth with a capital T, you're in for a long search but your test was pretty elegant and data . . . is valuable. Thanks for posting this.[/b]

Ditto :)

Dick Shine at SRS used to post the torsional rates for his swaybars, but I didn't see them when I checked his website this past summer. As I recall, the A1 bar that we got from him was rated about 1200 lb/in, and the A3 bar was rated about 900 lb/in. The original A3 bar was to be left in place, but the original A1 bars typically came off to save unsprung weight. There used to be two different versions of each, so I'm not sure if what he's currently selling are the same as my older ones. I think we went with the stiffest available in both cases.

[Nomex95]

I just added Dick Shines rear bar 2 races ago for my A2. Eli told me to buy the bar that was below the stiffest one that they have. I found the bar great at LRP at the runoffs. Just took a little while to get used to it in the left hander. Once I saw that the rear would stick it was preety good. I was running a old 28mm rear sway bar before which was fine but Dicks bar does feel better.

[wclark]

Dick is just down the road a bit so I know him pretty well, but we hardly ever see each other any more. I used his camber plates, spherical bearings and had Eli put together my first coilovers when I was building the GTI as a rally car. Eli set me up with 10" 300F/200R which never made it to the first stage. For gravel I quickly learned the standard formula with the A2 was softer. Front springs around 225-250, rear 150-180, no front bar and the stock rear bar. Longest springs you can fit over the shocks (I used 14"). Seems keeping the tires on the ground is way more important than maintaining camber or corner to corner weight transfer. I have used the 10" springs a lot though. The New England Hillclimb Association clubs (SCCV, SCCNH, KSCC) put on about 8 events each summer and I was encouraged to participate by Shine as well as the chief rally scrutineer for the RA (was SCCA) in the northeast, Don Taylor. So I put those 300/200 springs on along with a set of Victoracers and took the rally car hillclimbing several times a year. It wasnt hugely competitive because of the weight and limited suspension tuning, but it was hugely fun, and very inexpensive. Swap the springs and tires, lower the car, align and corner balance it and it was good to go.

Rally events have gotten too expensive for a guy like me who is partially retired, so I decided I would strip the rally bits off the car to cut the unnecessary weight a bit and just do hillclimbs. I think the 300/200 springs are a pretty good fit for most mountains because while paved they tend to be...well, mountain roads with heaves, patches and broken pavement. The springs need to be stiff enough to not bottom out too much but not so stiff as to punt the car into the trees because there is a frost heave at the apex of a fast turn. I was warned away from overly stiff springs by a few VERY experienced and successful hillclimbers and overthe last 3 years have seen second hand what can happen to one of these if theowner gets to carried away with spring rate while looking for another second per mile. My car feels well controlled and balanced but even with 4 degrees of camber I still put more heat in the outsides of the tires than insides so figure there is some room for a better contact patch allowing a slightly narrower (and potentially faster) tire with similar cornering grip.

I decided that over this winter I would improve the handling a notch by getting the camber under better control. I was pointed to this forum by a former GTI IT racer. Based on reading what road racers were using I saw a few approaches to this that went from very stiff springs and no swaybars to quite soft springs and huge bars. The common wisdom in all is higher rear wheel rates relative to the front compared to stock. Not unlike the rally setup. I began looking for some golden ratio (a number) that racers regardless of desire for suspension stiffness might approach for balance and presumably quick times, but found a very wide range instead. The major piece of data I am lacking is consistent swaybar rate information. When I decided to measure mine as a starting point, I quickly saw it was off by a factor of 2 when compared to what Per published. Dick promised to get back to me a couple weeks ago with some info but he has been tied up with events and I have been working for a change so havent the time to bug him in person. My springs are soft by road race standards but likely pretty close to as stiff as I can stand them, I figured to work mainly on swaybars. Without a lot of quantative data to work with I decided to start cheap with the OEM front bar (15mm on the 86-87 GTI by the way) mounted in urethane bushings and something similar in terms of increase in the rear (both interms of being cheap and in terms of % increase of wheel rate). Seemed like the 3/16" plate offered me the cheapest avenue and frankly the lack of data wasnt much different than for the $200-400 bars. The rear plate went on first and has been measured. I just completed refurbing the front and installed the stock bar again (I swapped out the armored rally control arms for lighter seam welded units and put in fresh spherical bearings, plus I cleaned up the old swaybar, installed the new swaybar bushings and rebuilt the endlinks). I havent measured the front bar rate yet but plan to tomorrow if the storm outside doesnt have EVERY leaf down in the gutters and yard by then.

[Eric Parham]

I just added Dick Shines rear bar 2 races ago for my A2. Eli told me to buy the bar that was below the stiffest one that they have. I found the bar great at LRP at the runoffs. Just took a little while to get used to it in the left hander. Once I saw that the rear would stick it was preety good. I was running a old 28mm rear sway bar before which was fine but Dicks bar does feel better.
[/b]

Not sure if Eli's recommendation for the softer bar was based on what your particular car had already (spring rate, etc.), or if there was some other reason. As I recall, some of the older A2/A3 bars used to crack the axle where the bolts went through. I can't quite remember, but I think that was solved by moving the mounting location to an area that was less brittle. My A3 bar has never had a problem, but it hasn't been raced (yet) either.