Central WA Baja

[baja5]

The difference in the arms could account for it as well. I know with bolting on my new lowers that the link pins don't seem to be exactly parrallel. So, I had to shim the spindles out more that I would normally like to avoid binding through the cycle. Unfortunately, I learned from Getrdone, that even though arms are welded up in a jig, when you weld one side then flip them to do the other side some distortion can occur. I would think if you can shim the side that is out to match the other side, you should be able to eliminate most of the bumpsteer. Not optimum when you pay a bunch of money for parts that should be identicle but I have learned that sometimes you just have to improvise.

[CentralWAbaja]

Wow the project is looking great.
I have not started with the bump steer issue yet, you lead I will follow
Like the levels!

Thanks...Yea my guys get a little irritated with me when I don't get the levels and lasers back in the tool trailer before Monday morning

[CentralWAbaja]

In my quest to understand this concept/theory that is called "Bump steer" I keep reading more and more that I can find on the web.

At this point what I am describing is not exactly bumpsteer per say... as it is more about watching the effect that cycling the suspension has on the steering shaft. Thus effecting the other wheel. Not really taking into account that the toe is changing through out the cycle and if one king pin is not moving completely free...it will just force the input on the rack vs changing the toe on the wheel that is being cycled.

So at this point I think I will start back where i started with rack mount... set the toe at "ride height" and then cycle both sides up and down measuring the change in toe as it is cycled and then go through the adjustments to see how it effects the toe.

Am I on the right page yet?

Am I starting to understand the theory?

[Leatherneck]

I think you are starting to get it. It seems like not a big deal but if you have one that is not setup right you will be in for a direction change when you hit a bump, land after air or compressing the susupension. Measure them on full extention and through the cycle to compression and see how much a diff there is in your measurements. Your on a roll now.

[CentralWAbaja]

Thanks for the feedback Leatherneck.... You too Baja5

So here is the direction I headed today.

Started with the rack mounted at 20* to the beam.... remember that the beam is laid back 5*

Then clamped two 4 ft levels to the brake rotors, centered on the top of the hub. I made to marks 16 inches each way of center(representing a aprox 32" tire) ALL of my toe measurements then came off of these marks.

Measured off the floor to the center of the hub at full droop & then at full comp.
Full droop = 17-1/2"
Full comp = 34-1/2"
Difference = 17" (x.40) = 6.8" rounded up to 7" for ride height
Ride height = 24-1/2" off the floor (approximately...I am a long ways from setting it for real)

I then rested the suspension on a set of blocks 24-1/2" tall (Ride height). Set the toe at 0" (measurement was exactly 64" on my levels) I then cycled both sides to full comp and measured to the marks on my levels again.
Front marks = 65-1/2"
Rear marks = 62-1/2"
Total toe in/out = +3"

Repeated the process with the suspension resting at full droop
Front marks = 65-5/16"
Rear marks = 62-13/16"
Total toe in/out = +2-1/2

I then did the same exact process 4 more times with the rack set at 25*-27.5*-26.2*-25.5* each time re adjusting the toe to 0 at ride height.

I'm not including pics of all of this....but it did happen.

Here is a chart of the rest of the measurements. ( sorry it's a little fuzzy )


Definitely looking for feed-back here.

I know that the travel# is not realistic. I will be losing some at the droop end of things for sure as there is no way i will get my shocks mounted with the arms that far down. And the extreme change in toe really comes on in the last little bit of droop so I may be having to let that dictate where the travel is limited in order to keep that toe number acceptable?

I guess that next question I have is the location of the rack front to rear? As well as up and down? All of the pictures I have looked at, it seems as though I am close, but how much does minimal changes there affect the final bumpsteer?

Is it worth trying to mess with that stuff?

Seems like if try to go up... it would help the droop and hurt the comp? I don't think I want to do that?

And if I could go forward... it would help both? But the lower part of the mounting plate is against the beam already so I would need to start cutting on that.

All of this is really just so I can go forward with confidence that the beam is in the right spot? (laid back 5*) I will probably just tack the rack mount in for now and do this whole exercise again after the upper shock mounts are located.

Sorry for all of the questions.... Just trying to get my head around this stuff. With any luck, I am headed the right way now and somebody else will benefit from this post in the future.

Thanks Again

[CentralWAbaja]

OK.... it's been 2 weeks.... nobody wants to talk about bump steer? ....Again?





That's fine we'll table that for now and move on. I "Think" I am headed in the right direction anyway

I know we all like pictures of our cages coming together sooooo....Have a look at these.

This is how I spent last Sunday and today.




Forgot to take a pic of the nice cross tube, that took me a couple hours to bend to match the arc in the dash...next time. (You can almost see it in the 1st pic)

And yes there is a lot of triangulation yet to happen.



I think we all like pics of cool hand made parts as well.... so this was todays project.

I know you carpenters will love this one.... used an old structural beam bucket for the steel....








To make these....



I know...No CAD design....No laser cutting...But dang, they took me all day and I think they look cool




But most of all......





I cut the tack welds....And....My doors opened for the 1st time in like 4 months Amazing how a guy could get excited about that....but hey, I am a simple man

[Ol'fogasaurus]

Daron, I just went back though all your posts and I have a question. The hoops you have over your tunnel, what are they for? Unless I missed an explanation, they are pretty wide in comparison to the tunnel. Your build is very interesting and fun (read as informative) to follow. You did choose a difficult way to go with the widening and lengthening of a whole VW (I am happy to see you did not try to tackle widening the roof line)

By-the-way, we get over the hill (Cascades) to the east side of the state quite often and usually go via I-90, Roslyn, and Cle Elm; keeping a couple of clips of silver bullets and several consecrated wooden stakes and a mallet handy. We used to ride at both the Beverly Dunes and Moses Lake dune areas but now it is mostly the southern Oregon dunes. I think we usually make the first rest stop at (I think it is called) Indian River or something like that, just east of Cle Elm.

I think we are supposed to motor home to the wine area this summer and maybe down to Goldendale to the observatory. My wife is into wines somewhat (but I did not drive her to drink, lets get that straight right now).

What kind of time line are you looking at in your build? I seem more work than even I have and that is a lot (I may be able to start working on mine again in a week or two, It has been almost two years now but maybe the end is in sight [pun intended]).

Lee

[Hedrock]

This is one nice looking 'vert. Can't wait to see more progress so .... Hurry up will 'ya

[Leatherneck]

Nice craftmanship! How come the big hoop over the tunnel?

[CentralWAbaja]

The hoops...? Short answer... they are temporary

Kinda explained it on page 1.... but I will try again...long answer

I started with an angle iron frame at the perimeter. This was to help establish the actual width of the car. It will service as the sill for the door to close against and the rear quarter metal to tie into something at the bottom. It has cross ties to hold the width while the cage is fabbed up. These will all be removed after the cage is established and the body tied into the cage. Only the outer ones will stay. It will show up a lot more in later photos.

So basically the perimeter frame(welded solid to hold it's shape) was tacked to the table at first until the actual length and width of the body panels were established.

I then cut the tacks loose and did the plywood top on the table and laid out the cage as well as the perimeter of the body. I then started fabbing the cage on that.

The body will have 3 inches of lift and the angle iron frame(door sill) sits (will be bolted) on a tube that is tied(welded) into the lower main rail of the cage...


kinda has a rock slider look to it instead of the traditional body lift look. Haven't taken any good pics yet...next time.


In this older pic you can see the frame being held up off the table by blocks before the rock sliders were installed.


In order to get the tunnel sitting flat on the table I had to cut the center of the frame out, and to allow for clearance, I welded the hoops in to simply hold the width of the frame. I have braced the body off to these hoop and the rest of the frame all along the way in order to keep every thing from moving. Once the body gets tied in at the doors and at the rear... I will cut all of the bracing out as well as all of the frame accept the sides(door sills and lower quarters)

[CentralWAbaja]

Thanks for the compliments guys...

Progress time line is sketchy, as I am working tons of hours and a long ways from home....but at least I am working



Lee,

I am located just west of Cle Elum by about 10 miles...not very far off of I-90 less than 5 min. Shoot me a PM when you know you are headed past this way and we can make some time to meet....I would like that.

Not sure if we will be making any trips to the Oregon coast this summer...usually spend a week there in late July or August. Not sure if work is going to allow it this year...I will probably post it up if we do make plans.

[DesertGuy]

Central, I was looking at your posts on "bump steer" and am not totally sure what it is you are after. That being said, all suspensions "degrade" at the end of their cycles. How much or how quickly they "degrade" is dependent on other variables. As an example, if you have designed in minimal tire scrub, the suspension will degrade quite rapidly towards the end of the cycle. These are the differences between how much you can cycle (mechanically) a suspension and how much the suspension is limited to... to account for other variables. It is very common to "limit" suspension travel to gain in other areas...

The term "bump steer" (IMHO) is a terrible naming convention, it is more adequately stated that "bump steer" is simply the tires deflection, either in or out, as the tire travels through its cycle. This relationship is not forced by where the spindle is mounted (upper/lower arm) but how well the tire "plays" in relation to the steering linkage. There are three arcs to consider while looking at "bump steer". The first is the upper spindle mount, second is the lower spindle mount and the third is the outer tierod mount on the spindle. All three arcs MUST move in unison through the cycle.

The tricky part is to find where the inner tierod mount should be that allows the tire to cycle without changing the tierod's length. That, in theory, will allow all three arcs to work in unison. The best way that I have seen is to determine the coincident of three different arcs.... and those arcs being ride height, droop and bump. Finding the coincident of the ride height arc, bump arc and droop arc will determine where the inner tierod mount should be located. You will find, that depending on your design, you will need to limit travel depending on the rate of degradation.

Once the spindle is attached, via the steering linkage, the parameters have been set. Obviously, the tierod cannot change lengths to accommodate any changes... so any changes will be seen in the tire's movement from the center reference point. As another example [droop], if your rack is too high, the distance will increase (become longer) between the rack and the outer tierod mounting point. Since the tierod's length is determined, the result is that the tire will be pulled in (toe in) as it travels further into droop territory. Understanding that, if the rack is set too low... toe out can result. Also, moving the rack fore and aft will also have an effect on the "needed" tierod length and those differences will be seen in the tire's deflection, either in/out.

Most will "set" the bump steer parameters while being in a "straight-ahead" orientation. As turning the tire throws everything out the window in a rack design.

There is no such thing as zero bump steer, it can be minimized but never eliminated. Having as little as possible is the optimal goal. Having too much will make for a terrible handling car, especially without power steering. The slightest deflection can feel like the steering wheel wants to rip its way out of your hands.

I guess that is enough rambling...

[CentralWAbaja]

DG,

Thanks...what I am after is... some reassurance that I am headed the right direction...This is the 1st time anyone has said to "consider all three arcs in play." This is what I have been thinking, and wanted to draw it and post it to see if I was thinking about it correctly.

I know this stuff is old school for some...but for me, I have never attempted to build anything like this from scratch....I am a house guy. Like I have said before, I have never even seen anything like this in person. I am just trying to understand all of this stuff as well as think of as much of it as I can in advance.

Again thanks for the feedback

[Ol'fogasaurus]

DesertGuy, good definition on the suspension issue. It should be measured off the spindle (tolerance, that amount of variation allowed off of the ideal dimension, during the manufacturing process of, in this case the spindle and the trailing arms) though.

As you lengthen out the trailing arms, what would have been an acceptable setup in stock form (German engineers design very tightly to a very close design standard they have been given. Their designs are that precise and we, as risk takers, go several steps beyond in both design changes and product use) is magnified as you deviate from the original design. Also; each trailing arm is going to vary for many reasons (e.g., heat build up during welding, length variations (even if they were cut in the same jig with the same cutting method and tooling] will give some variation and each sheet/stick/block/plate [tolerance in the manufacturing of materials] of material is going to be different and react different when being cut or welded, just to name a few variations. As you hold tolerances down (tighten up on them) the price of the finished part goes up exponentially.

(just for giggles) Since dimensioning changes in the ’70 (USASI Y14.5 (e) as I remember; e.g., thee elimination of stacked dimensions for example, the expanded use of datum’s, and changes in tolerances; e.g., the elimination of the nominal tolerances and just working to the range dimension) eliminated a lot of scrappage problems. Manufactures have gone to “go, no go” gauges to check their work. These gauges accommodate normal tolerances for large manufacturing runs but for hand built, high tolerance stuff, I don’t think that they are what is wanted for what we are often doing. When we are looking for precision, nominal may be more important than dimensional ranges (I can accept parts within this range) could get you.

Central WA guy; you mentioned CAD design. CAD programs can draw to as many decimal places you want and you can noodle your design around and come up with a perfect, (can find) no fault design but then you have to deal with tolerance during the manufacture. Based on the chart and other information (that my eyes glazed over during reading ) you posted, you seem to have done quite well in your wanderings though setup. Good job!

Central WA guy, I thought that maybe I had missed something in your explanation when I reread the whole string. You explanation of reasons for doing it makes sense. You got support and working room at the same time. Another “atta boy” Remember though, a single aw $**t can wipe out many “atta boys” so be careful.

I think we are heading down to the dunes around or just after the 4th. We usually stay off the dunes the weekend of the 4th as it can be “Nutsy Fagen” out there. I think (not sure yet) that we will also be down there some time in August or September. Not sure what the rest of the family has planned on but I do know that there are some other plans for vacation time out there.

It would be good to meet you. There are a couple of guys from the left side of the Cascades that I have met as well as a several from Oregon. We never can learn too much from each other.

Lee

[DesertGuy]

DesertGuy, ...It should be measured off the spindle though.
Lee

Lee, I may be misunderstanding your comment but I measure amount of "bump steer" off of the leading edge of the tire. I will also confirm that measurement by measuring the trailing edge of the tire. A measurement taken at the hub mounting surface of the spindle can give you a false reading... that measurement needs to be "ran-out" to the tire's edge to see what impact it will have, especially when you are dealing with tires 33.0" (16.50 run-out) and larger. As stated, I may have misunderstood your post... in that case, disregard.