DIY String Alignment

[jimgood]

I've wanted to do my own alignments for some time but didn't want to spend stupid money for the tools. I've looked at lots of string alignment DIY videos and blogs. There are lots of ways to do this.

My criteria for the string holding tool are the following:

• Attaches to the car so that the string remains aligned when rolling the car back and forth after a toe adjustment.
• Light weight
• Easy to build
• As compact as possible but I don't want to break it down or set it up every time I want to use it

My plan was to connect 1" aluminum tubing together to form a framework that hangs at each end of the car and supports a long tube to which the strings are tied. I searched for tubing connectors but could only find very expensive options. Then Ed Higgenbotham at Grassroots Motorsports pointed me to 8020.net and their Quick Frame Connectors. They turned out to be just the trick.

I only had a rough idea in my head of what I wanted so I ordered:
Part Qty Price
9330 4 $56.00
9250 8 $20.80
9220 4 $10.40
Subtotal: $87.20
Shipping & Handling: $19.07
Tax: $0.00
Grand Total (Incl.Tax): $106.27

I also got 4 - 1" sq. x 96" aluminum tubes with .065" wall thickness from the big box store at just over $16 each. So we're at about $170 all in.

I ordered 8 of the 9250 3-way corner connectors but I really should have only ordered 6 of those and then 6 of the 2-way corner connectors. They're the same price so it doesn't matter much.

Here's the finished front frame. I'll use C-clamps to secure the long horizontal bar after the strings are attached and it is adjusted to the proper height.

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Here's a side view of the front frame assembly with all of the parts marked out. I'm not providing dimensions because they are specific to my car and wouldn't be of any use to someone trying to build one; even the same model car.

9220 are the 2-way corner connectors (90 degree elbow). In the front frame, I only used one pair as the "hook" that hangs the frame on the front fascia of the car. 9250 are the 3-way connectors. I used these to connect the outer vertical parts of the frame and the cross bars. I could have substituted 2-way connectors at the bottom; again, not a big deal as they're the same cost. 9330 slides over the vertical tubes and the extra nub sticking out is what I'm using to support the string bar. Straight from the factory, they're a very tight fit. I used a very sharp 1" wood chisel to shave off some material on the inside so they weren't so tight. I went a little too far on one but it will do.

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The rear frame is basically the same though I needed some tubing on the "hook" at the top of the trunk.

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Not as cheap as simply tying string to jack stands but I think this will work out a little easier. I should be able to set this up once and have it be the correct height, only needing slight side to side adjustment. This could have been done for less than half the cost if I was competent at welding aluminum (and even cheaper if I'd made it from steel).

I'll try doing the alignment this weekend. I just replaced my rear trailing arm bushings so I know the rear toe has to be adjusted. The front has felt okay but I noticed uneven wear in all four tires on the inside. Goal is 0 toe in both the front and rear.

 

[dla]

Subscribing to this one for future reference Good idea and great execution!

 

[kursplat]

nice. i've thought about doing this style but it's about # 987 on my "i'm sure i'll get to it this weekend" list. so what are you planning to use for measuring?

 

[Balor]

Subscribed, I like it.

rngr1

 

[jdieter]

I inherited a Bear toe gauge from my dad. It's a square tube with adjustable stands and targets and a spring loaded scribe on a smaller stand to mark the tire on the centerline. Same principle as stringing, but I like your scheme. I also use strings, drilled 2 pieces of 3/4 electrical conduit clamped together so the strings will be parallel. The next time I do an alignment I'll copy your plan and scheme up a way to mount the conduit off the car bumpers I made turntables out of 1/4" lexan sheets sandwiched together and scribed with degree marking for camber. They only rotate in one plane unlike commercial turn plates.

 

[Bopbop]

We would use the string method to set the toe on the dirt track race cars years ago. We also had a caster camber tool sold by Longarch I think. This always worked really good. One thing that we learned over time was to always use the same spot in the shop (we had marks on the floor) to do the setups and have the tire pressures set correct.
The little things made it easier to return to the same base line and repeat the setups.

 

[sweet victory]

We would use the string method to set the toe on the dirt track race cars years ago. We also had a caster camber tool sold by Longarch I think. This always worked really good. One thing that we learned over time was to always use the same spot in the shop (we had marks on the floor) to do the setups and have the tire pressures set correct.
The little things made it easier to return to the same base line and repeat the setups.

I think you are thinking of Longacre.

http://www.longacreracing.com/

 

[jimgood]

It's basically done. I added some locating tabs to the string bars (see pics). I also marked the trunk where the "hooks" should be located. Once I've set this up once, I should be able to mark all the locations. With that done, that should save time for the next set up, requiring only a minor tweak here or there.

I set up some strings just to get a feel for what issues I'll run into.

• The supports for the string bars are sliding sleeves. As I stated above, they're tight from the factory and I whittled away some material from the inside to make them slide easier. I went too far on one of them so it slides too easy and won't support the weight of the bar. So I had to adjust its height and clamp it in place.
• When attaching the strings, I have to clamp one side of the string bar to its support in order to keep from pulling it off. Not a big deal.
• Adjusting the height of one side drops the other side so it's a bit of a dance to get it right on both sides. Once I get it right, I should be able to mark the height on the frames and use it over and over. In fact, I might just tape the sleeves so their vertical position is fixed.
• I didn't think about this initially but it's a good thing I didn't get something that fixes the string bar at 90 degrees to the vertical struts. That would mean a fixed horizontal position in relation to the frames and that might not line up on each side with the center of the wheel hubs, depending on how a given car is set up. For example, an oval track car is going to have much higher ride height on the right side. So the bars would need to be at an angle to the frame. Any fixture attaching the string bar to the frame would have to have the ability to not only pivot but also allow the bar to slide through because, as the angle changes, the distance between the fixtures changes too.

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View media item 84929

 

[zkling]

I just use heavy jack stands, tip being though with heavy (~80lb test) fishing line. Pulled tight the fishing line makes for a very crisp mark to measure from. Using a 6" 1/64" scale, can get VERY close if you take the time.

 

[jimgood]

Thanks. I've see the jack stand method too and it's certainly cheaper if you don't mind rechecking everything after you roll the car. And I'm using fishing line as well. I tied it on the front bar and I'm letting it hang over the rear bar with 6 big washers tied to the end to weight it.

*******************************

I did my alignment yesterday and then went for a test drive this morning. Steering wheel was off center, which bugs the **** out of me. Seemed to be pulling very slightly right on the right side of the road but if I got on the road crown, it tracked straight, so that's normal. Tracked straight under braking. Overall felt pretty good.

Pulled back into the shop and set everything back up. Then I realized I made a monumental mistake in my previous attempt.

I stupidly picked an arbitrary measurement for the string offset from the front and rear hub centers. The result was the strings being wider at the front of the car than the rear. Brilliant! Just brilliant.

So this morning, I set the strings the same distance apart at each end and taped the string in place on the bar to make sure it didn't move. Then I set about measuring the distance from the hub centers at each end. If it was off, I moved the entire frame half the difference in the direction of lower number.

For example, if the LR was 95 mm and the RR was 90 mm, I moved the frame 2.5 mm to the right so both measurements land on 92.5 mm.

Every time one end is adjusted, the other end needs to be rechecked and adjusted. This only took a couple of minutes.

Now I need to adjust everything again but I'm on my Sunday morning coffee break at the moment.

 

[jimgood]

After my test drive this morning, I pulled the car into the shop with the steering wheel centered. Then I set up the strings again as I stated above.

This time, I kept the car on the ground. I marked the position of the tires on the cement, rolled the car forward then placed a stack of wax paper in each tire position. Then I rolled the car onto the wax paper.

The wax paper worked great. When I adjusted the rear toe, with even a 1 mm change I could hear the tire moving on the wax paper before I could see it move.

When I went to do the front toe, it was already perfect. I don't get it. At a minimum, the wheels should both be turned to the right a bit because I pulled in with the steering wheel straight.

While I stewed about that I re-measured the string bars and put scribe marks where the strings are to be positioned. This will make it simple to set up next time. Now all I have to do is place the frames and bars on the car, hang the strings on the scribe marks then shift the frames to get the strings the correct distance from the hub centers.

 

[kursplat]

I stupidly picked an arbitrary measurement for the string offset from the front and rear hub centers. The result was the strings being wider at the front of the car than the rear.

yup, that's why i have post-it's scattered around with the front and rear widths of my cars listed