Lotus 61 Restoration Project
Part Five

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Fiberglass restoration, paint and chassis alignment:
Welcome Back! With this 'edition' you will see some real progress of a slightly different nature. It has transformed before my eyes from a strong but pretty 'battle worn' racer into something so pretty it would 'bring a tear to a Glass Eye'. So without further fanfare.....

Since the car is being repainted I've removed the body and sanded and prepped it for paint. At the same time I've inspected it and repaired several fatigue or stress cracks in it. Now let me be the first to tell you: this is NOT my specialty. It takes me about a day to do what a 'pro' does in an hour. When I had the fiberglass repairs completed to the best of my ability I took the body to Concours Body Shop in Reno. They had made me "an offer I couldn't refuse", so I expected it to take a couple weeks; with their guys working on it when they didn't have regular customer cars to work on.

The cockpit cover after sanding. This much of the preparation is pretty easy, provided your proficient with sandpaper. (For me, sandpaper is a precision tool I've never been trained on!!)

One of the places the Lotus body tends to crack are the sides of the cockpit cover near the rear. I've ground out the old fiberglass (the dark area on either side of the meandering white line visible through the fiberglass patch). Next is to chop some matte into fine pieces, mix it with resin and pack it into the channel I've ground out. Before it sets up I cover it with a layer of matte then another layer of woven roving as you see here. After it sets I sand it then fill as necessary with glazing putty for a smooth finish.

Here's the other side of the cockpit cover where I've sanded the repair for prime and paint.

Two weeks pass and Concours has the body ready for me to pick up. Gil Grieve (owner of Concours Body Shop in Reno) and I have discussed the colors I want and all the special techniques needed. Since a formula car is so succeptable to rock chipping he applies "rock guard" to the nose and underside of the body. He also uses something he called "liquid paint" that is more resistant to rock chipping.

The cockpit cover, undertray and engine cover:

The next step is to install all the accessories and have new numbers and letters made.

Alignment: The car should be aligned as it will be driven. That means with fuel in the tank and the driver in the drivers seat. Tech tip: Gasoline weigh's six pounds per gallon. If you don't want to (or cannot at his time) fill the fuel tank then calculate the weight of a half tank of fuel. (20 gallon tank would be ten gallons.. times six pounds per gallon of gas, or sixty pounds.) Stack this weight on or around the fuel tank. Compensating for 'my weight' is easy in a formula car. I weigh 250, and 'attired' for racing, plus the weight of the fiberglass body, its probably close to 270 pounds. I set a piece of plywood on top of the cockpit frame rails then set three Cortina engine blocks on the plywood. This fairly well approximates my weight and gets it pretty well aligned on the center-of-mass of the car.

Alignment is easy; maybe time consuming if your not completely 'adept' at it, but this will go a looong waaaay toward getting some "free horsepower". If we were 'drag racers' then chassis setup may not go much further than controlling the effects of torque in straight line acceleration. In 'road racing' we are well aware that platform stability is vital, and at the same time we are subjecting the platform to constantly changing conditions. Your setup is a compromise.... If every straight were the same length and every corner exactly the same, no changes in surface drag and of course no elevation changes, then a setup may be what we could call "perfect". But everything is in constant change in our sport, so our 'setup' is a compromize of all the dynamics that we encounter. Before going further let me recommend the series of books by Carroll Smith; all with similar titles, "____ To Win". There you will find more information than you can ever imagine or hope to understand (unless your a "rocket scientist" in your 'day job').

What does suspension do for your race car? It smooth's surface irregularities, reduces/controls weight transfer, keeps the tire contact patch aligned with the car while still in contact with the track, provides stability at critical attitudes of the vehicle relative to the roadway. I could go on and on... y'all get the picture.

Setup: First and foremost, the surface (garage floor) that your doing your alignment on must be LEVEL. Since most garage floors have a built in slope for drainage, you can plan on having to do something here. Several years ago, while "testing" a surveyors total station I conveniently "mapped" my garage floor. After all that scientific ingenuity it turns out a 2X6 under the front tires brings the car up completely flat and level. I painted marks on the floor for future reference for the four tires.

Another way to do this would be with a spirit level; preferably four feet or longer. Mark the location of your tires on the floor then using the level, measure and determine how much rise or fall there is. Write it down. Now if you just did the rear wheels repeat it for the fronts. (And if you did the fronts first, repeat it for the rears). Write the result down. Lastly, measure from left rear to left front and right rear to right front. Write it down. Now you can simply subtract some numbers and determine how much you need to raise the 'low end(s)'. (Don't forget, you need it leveled left/right as well as front/back.)

I have a couple basic tools that I use for aligning the Lotus: camber gauge, steel tape and a very large divider.

Once the car has been 'leveled' I can check/set the ride height. This is really how high off the ground the front and rear of the car is. On the Lotus its measured to the bottom center of the back of the frame and in front to the bottom center of the pedalbox bulkhead. Adjust it by raising or lowering the spring perches on the shock absorbers (coil over shocks). Tech Tip: Before beginning the alignment disconnect the sway bars. Leaving them attached can alter the spring rates on the suspension.

Once I have 'leveled' the car and set ride height I check the camber at the four corners. The first step is to adjust the camber as necessary. My initial settings are 1 1/2 degree negative for the rear wheels and 1 degree negative for the fronts.

The next step is installing alignment bars front and rear. I've made alignment bars specifically for my car that attach to the front and rear suspension. In this photo you can see the front bar. It has square tubes that clamp over the front suspension rack. When installed it centers the rack and prevents left/right movement. Near each end is a string that gets pulled under tension to the rear bar.

This is a photo of the rear bar. It bolts to the bearing carrier on the gearbox. In the photo you can see the string pulled from the front bar.

What happens is that once adjusted the strings are parallel to each other as well as parallel to the centerline of the car. When the car was back at the bare frame stage I took several measurements to check the cars centerline. (I have a mark on the transmission cradle and pedal box bulkhead.) Having previously confirmed the centerline, after I stretch the string from the front to the rear bar I use that big divider and measure from the centerline mark to the string at each corner to assure the strings are equal distance from the centerline. This assures that the strings and bars have formed a perfect rectangle although its the strings I'll be using for alignment. The final check is to measure (with the steel tape) and insure the string is the same distance on each side from the rear wheel hubs and front wheel hubs. At this point I've confirmed that the strings are parallel, that the car is perfectly centered between them, and that the car is not 'kinked' inside the strings. (Note: the more time you spend to insure everything is set up to this point the more likely that your alignment will be accurate).

The next step is to put one edge of the steel tape against the wheel bead and measure the distance to the string first AT THE BACK OF THE WHEEL, then AT THE FRONT OF THE WHEEL. Write down your readings as you go. Make absolutely certain sure that you don't transpose your numbers. (As an example, if you read 4 inches on the rear of the wheel and 4 1/4 inches on the front of the wheel, that would indicate 1/4 inch TOE-IN. If you transposed those numbers then obviously you would incorrectly interpret that as 1/4 inch toe-out). I always, Always, ALWAYS measure the back of the wheel first and front of the wheel second to reduce the possibility of transposing.

Having measured and written down the readings front and rear for all four wheels go sit down and look at your numbers and calculate what the toe-in or toe-out is for each corner. Then look at the car and ask yourself if the numbers "look right"? If your measurements say toe-in for a certain corner and it looks like its toed-out, remeasure!! If your not 100% certain sure, remeasure them. (Two old sayings: "measure twice, cut once" and "I cut the board twice and it was still too short!") Trust me when I say this... what seems like a miniscule error in alignment will make a good handling car HORRIBLE (and unstable) TO DRIVE!

Having completed these measurements and assured yourself the numbers are good, look at the results and determine which corners need adjustment. As an example, lets say you desire 1/16 inch toe-in on each rear wheel and you measured 1/8 inch on the left rear and zero on the right rear. You CANNOT say the rears are good at this point even though the measurement on the left rear equals the total desired toe-in of the rear. If you left the rears alone at this point the car would not be straight when driven... In this scenario, make an adjustment to the left rear control arms to reduce the toe-in to 1/16 inch. Now, go back and measure ALL FOUR CORNERS AGAIN! What you are going to find is that when you change one setting everything else gets changed!

Next step, assuming the left rear toe-in was 1/16 inch when you remeasured, adjust the right rear until it has 1/16 inch toe-in. Now remeasure all four corners and record your readings. Even though you've not touched the front of the car I'd just bet the front measurements have changed slightly. You might even find that the left rear changed slightly as you 'fine tuned' the right rear. This is normal.. your not doing something wrong.

OK... Walaaaaaa.... you've got the left rear and right rear at exactly 1/16 inch toe-in on each side! Now, before you start on the front, recheck the strings to insure they are still parallel to the centerline of the car. (Sure, you can "cheat" and say "ahhhhhh, it didn't change nuthin'......", but next race when I pass you and you wonder where I got the extra 25 horsepower.......... Now you know!!)

The caster isn't adjustable on the Lotus and I've already set the camber, so whats left is the front toe-in. The front alignment bar locks the steering rack centered, so it's a relatively easy job to adjust the tie rods and move the rod ends in or out as necessary until they are each 1/16 inch toe-in. Once the toe is set, recheck the toe settings for all four corners. Your 'almost' finished with this phase. Now recheck the camber on all four corners. If nothing needs adjusting then your finished setting the toe-in. If you do need to readjust camber on one or more wheels then recheck the toe in afterward. (Any time you change one thing you need to recheck everything else).

Corner balancing: This requires a set of electronic or mechanical scales; one under each tire. At approx. $1,000.00 for a scale set its a luxury I cannot afford to buy. Fortunately I have a friend who lets me borrow his scales when he's not using them. (Off the subject of restoration for a moment, that is one of the things I really enjoy about historic motor racing. Unlike other venues (like SCCA) where everybody has a tent and walls of secrecy around their paddock, everything and everybody is open and friendly here. We help each other a lot and loan each other tools and spare parts, and I for one really appreciate and enjoy the cameroderie).

Follow the directions for the scales. Most electronic units need to be 'zeroed' before the weight of the car is loaded. Alright, you have the car on scales. If you had to jack the car up to get it on scales then you need to assure the suspension is compressed to normal ride height. Turn the scale computer on (assuming an electronic set of scales). Read and record the weights on the four tires. In balancing the car, I read the following weights: LF = 221#, RF = 235#, LR = 345#, RR = 332#. Our goal is to have the LF equal the RF and the LR to equal the RR. We achieve this by adjusting the spring perches on the shock absorbers, which increases/decreases the spring tension and weight on the respective corner of the car. Also, in changing spring tension you always work diagonally: LF to RR and RF to LR. Looking at the weights above, note that the LF/RR total 553# and RF/LR total 580#. SO.. in our little 'balancing act' here, we have to 'change' the front weights by 14# and the rears by 13#, and we also want to maintain our ride height. Fear not... its not that difficult.

First, make small adjustments and check the results every time you make a change. Every time you change a spring perch setting compress both the front and rear of the car several times so nothing is sticking, everything is free.

My adustments were as follows: 1/2 turn soft on the RF, 1/2 turn soft on the LR, 1/2 turn tighter on the RR, 1/4 turn tighter on the LF. Ride height remained the same, and the scale readings were: LF = 228#, RF = 228#, LR = 338#, RR = 338#. (Pretty dog gone close to "dead on"!!)

After this I remove the ballast and recheck that the numbers are still in balance, then install all the body panels, fuel, oil, water and get a final reading: in this case 943#.

Before taking the car off the scales I reattach the alignment bars and recheck the alignment. I had to slightly readjust one corner toe-in, otherwise its ready to race.

The "final evaluation" will of course be on the race track itself. My recommendation for track tuning is to only change one thing at a time, then write down the results of what you wanted it to do and what it actually did. Make ONE CHANGE ONLY then test it. Write down the results of your test so you know what changes did what. (Invaluable this time next year when your trying to 'cure' the same problem that you had today.) Tech Tip: Go to the Roger Kraus Racing website and under the tech section copy and print the "symptom and fix" chart for correcting over and understeer. http://www.rogerkrausracing.com/

In this part we have covered body and fiberglass repair, and painting the car. We have also covered suspension alignment. Things that are still left are minor; such as tuning the engine and things like that which you would do before any race weekend. There are two parts left. The next part will be acknowledgements for parts and services, etc. The final part will be the test day at the track.

Thank you very much, I hope you have enjoyed this series. It represents approximately 250 hours of work and took about two months. (The original restoration in 2001 took one year and 1,000 hours, so I guess I'm getting better at it). And what do I have to show for my efforts? You be the judge!
Carl..... and Lotus 61M 61/FF/79