Front end alignment?

[Timothy Keith-Lucas]

What a wonderful discussion! I've learned a lot in the process.  Thanks, guys.

 

 

[wdb]

2 hours ago, 7Westfield said:

a homemade set of these is what I use for toe adjustments

https://www.pegasusautoracing.com/productdetails.asp?RecID=12736

 

and a digital level for camber

 

The problem I see with those toe plates is that they measure one wheel relative to the other wheel only. They'd be okay for quick adjustments on known good frames/chassis. The string method provides measurements relative to the entire chassis and would show issues such as a tweaked frame or a rear (solid) axle that is not in line with the front axle. Illustrating what I mean:

 

 

As for measuring at the tire -- every instruction set I've ever seen says that the spec is a measurement at the wheel edges, level with the hub. For camber you have tire bulge at the bottom to contend with; for toe you would need to compensate/calculate for the larger circle diameter. (Admittedly a small difference.) Take a look at Hunter or other professional-level systems. They take readings relative to the wheel.

[7Westfield]

No doubt the string setup is better, but for quick + dirty job, the plates are fine

 

At one point, when I was racing my Supervee, I had a collapsible frame that went around the car to string it

but, for a solid axle 7, at home   nah

[CarlB]

Doing an alignment is critical to optimizing the handling of the car. The first thing you want to do is get the car level and at ride height. You can use floor tiles to level the car, and don't forget to check the tire air pressures. you might want to add some wax paper between the floor times to help set caster. Some racers check the diameter of the tires. Next thing to do is center the steering rack, see below. If you are going to scale the car, you should do that next. This should be done with you in the car and the fuel tank at a level that you use every time you scale the car. Next you want to make sure the rear axle and the front axle are in line. The string alignment box and a measurement of the wheelbase on both sides will give you that information. I like to use a square tube for the front and rear point to pull the string over. I think it is easier to get the measurements. The point of the string is to set up a box that is parallel to the axles. The string is parallel when these requirements a met:

When the distance from the front tube to the rear tube is the same on both sides

When the distance from the string to the rear axle is the same on both sides

When the distance from the string to both sides of the front axle is the same, but it does not have to be the same as the rear. 

When the distance between the strings on both tubes are the same. 

You can speed up the process by measuring from the wheels back to the tube and making the measurement the same when you are setting everything up.  

The strings are now in the way to set camber if you want to use the strings to set toe. Camber gets done next, then caster. After the caster is set go back and check camber. I don't set toe with strings. It is difficult to get measurements, you are trying to measure very small angles and wheel diameter makes the measurements very small. Keeping the ruler level makes a difference. I use a Dunlop gauge; it multiplies the measurement. But the toe plates talked about above work well. Tires have an overlapping splice done in the construction. You need to make sure the toe plates are not on the splice. There is a slight bulge on the splice. It would be better to measure with the toe plate in contact with the wheel and not the tire. The measurements are taken about 3 feet apart. You are trying to measure an angle, and the measurement is easier to make 36 inches apart than 13 inches apart. The problem is that you are measuring total toe, and you want individual wheel toe. If you use strings or toe plates the first thing you have to do is center the steering rack. I have a mark on my rack where the shaft from the steering wheel goes in the rack so I can center the rack. When you do a string alignment this is important for centering the steering wheel, but it is more important for bump steer. If you use toe plates you have to do it if you want to get the toe set the same on both wheels. If you look down on the steering rack it is clamped to the chassis. In the center of the rack look down on the chassis and at least on my car there is a small hole. That hole is the center of the chassis. On my car the clamps that hold the rack are equal distance from the center line. I use a very thin tape to measure from the brackets to the nut on the steering arm. They have to be equal. If you want to adjust bump steer you need bump steer measurement equipment. You can make it or buy it. It is two rectangle pieces hinged together. One sits on the ground the other is in contact with the wheel. You need a flat plate attached to the wheel and the rectangle has a bolt and a dial indicator in contact with the plate on the wheel. You set the car at ride height and remove the coil over. Put a jack under the A arm and set the suspension to ride height. Then you zero the dial indicator with the bolt in contact with the wheel. You use a jack to move the wheel through its travel and record the readings. The readings produce a curve of the toe changes as the wheel travels up and down. You can change the toe change by shimming the rack or if you change to rod ends for the steering arms changing the height of the connections to the spindle.           

[jbcollier]

I would recommend getting a professional alignment at least once.  They quickly and easily can point out any bent or damaged parts.  I restored my Europa and did a home alignment.  Drove fine but I wanted to be sure.  The professional alignment revealed two bent front uprights and the rear thrust angle was out.  I replaced the uprights and set the rear toe in relation to the front and all was good.

 

The "Triumph" front uprights are easily bent.  Of the four used ones I have had on my Europa and Seven, three have been bent.

 

Sadly, the Seven chassis unit is also somewhat easily bent.  Not easily as in bent by a bump in the road but hit a curb hard and it is a possibility.  Most of us do not know the previous history our Sevens so it is well worth a thorough check.

[Marek]

Many years ago I decided I wanted a good alignment from someone with motorsports experience, so I asked a few people at the next autocross.  One name was repeated a couple of times, so I take my car to the shop.  In the back corner was his flat patch.  His alignment rig was linoleum tiles under the wheels and a spray bottle of soapy water for lubricant, and strings with levels around the car.

 

Later when I was working in IMSA and GrandAm, all the teams I worked for string-aligned their cars; including P1, P2, and GT3.

 

I learned that stringing requires more skill, patience, and attention to detail.  But the results are good enough for winning races in top motorsport.

 

Recently I picked up this $35 toe/caster/camber plate set for doing quick checks: https://www.ebay.com/itm/114130836633

 

I do agree a fancy rack alignment is a great baseline and a cheap form of inspection for worn, bent, or broken parts or other damage.

Edited 19 hours ago by Marek

[IamScotticus]

This is getting good.  There was another thread on alignment that started as a hijack. It was so good, @JohnCh moved it.