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Ford GT LM
#21

Posted Today, 04:34 AM
The Road to Le Mans 1/32: what a trip it has been
Almost done with my backlog posts on the Ford GT LM, I must say, looking back to this topic, wow I really went all the way with this little racecar. 
And as in live, the road travelled was almost more rewarding and interesting than arriving at our destination. 
Because what was initially a simple Plan B to get us to Le Mans, quickly grew into something much more complicated.
The challenges this little Ford raised have tought me a lot, the lessons learned already being applied in new projects

But now after 6,5 months, 8 pages full of post, almost 10.000 views, it is time round things up and bring this project to a close.
I must say, posting and building at the same time did 
cause this thread to swerve off topic from time to time and had me skipping from one topic to another.
So this one...with a bit off hindsight, can be considered as the Ford GT LM epilogue.


[Image: post-18820-0-73983800-1566119398.png]


Ford GT LM...body double
For our trip to Le Mans two complete Ford's were build, one would serve as a test mule and was destined to do most of the free practice running the other would be kept clean and fresh for the 24hrs race.
We ran one car in the 2017 livery and one in the "special edition" 2018 livery courtesy of Hornby Hobbies. So wha t was so special about the 2018 car?
Well, when I talked to Simon about our plans to do the 2018 car...if we had the time. He mentioned that he might have one for us laying around.
Its was a dis-approved pre-production sample with a minor discoloration error. I could have it under one condition: That I would not sell it after the race!
(apparently like a misprint on a stamp this tends to make such an item rather unique and increase its value somewhat)
Well Simon, rest assured, this little Ford will never leave my possession, as a matter of fact I might pick up a second 2018 car  when they will be released 4th quarter 2019.
Because the metallic color of the car is just stunning.

As you can see on the picture right. I did some paint tests as I needed to touch up the paintwork on some of the areas where I'd modified the body work. 
In the end I decanted some Tamiya TS 39 & TS 95, mixed 1:1 and applied it with an airbrush.
[Image: post-18820-0-76947200-1566120248.png]
 
Lights: Short circuit and short cuts
One of the things I never got to post prior to the race, the lights. Main reason of course  was that we still needed to mount them as we left for the UK on Friday.
Me shorting out the light chip on Friday evening just before the first qualifying session didn't help. Luckily we had the body double which, with a very rudimentary light set,
allowed Wayne and Stephen to do some night running. Z-machine had send us an ample supply of spare light sets, so the alarmclock was set for 05:30 on race day, first job 
was to start repairing the lights of the race body.
Funny how time flies when you most need it, in order to get the car finished in time for the start of Saturday morning 2nd Qualification session we would need to make some (short) cuts.

With the Ford sporting 8 leds at the front and no time to properly trim the wiring, using the stock wires would add another 1,5 - 2 gr to the body.
But as I went through my spare box I found a spare light set Fola had made for the Toyota TS040 we raced in 2015.
The headlights of the Toyota had 3 tiny round smd leds and one square on each side and they were mounted on very thin laquered armature wire.....and guest what... 
..not only were they a perfect fit for the Ford's headlights, they were also much lighter.
[Image: post-18820-0-27456600-1566128290.png]

Lights: Friend or Foe
Where on a race car the lights are there for the racer to be able to see the track, on a slot car the lights are there for the racer to be able to see...his car.
And believe me on a digital track as big as the 1/32nd La Sarthe...that can be a harder job than you may think. Running in a pack going into the esses or rounding Mulsanne corner...
...every bit of extra light that will help you to identify which car in that cluster of lights belongs to you...really makes a difference.
With the distinctive triple headlights and two fog lights, we had the front covered. The sides...hmmmm not so, ok those extra identification lights behind the cockpit...
...we did not want them to be as bright as the neon light Ditslot had done the previous year. But due to the short cuts we had to make repairing, all the side lights were a bit dim. 
We also ran with the flaming exhaust led on the right side as this was the visible side and helped you spot your brake point on the Mulsanne Straight.
where the car lacked identification most was at the rear. Sure the Ford's taillights were pretty big, but they shone just as bright as all other cars.
An extra identification light at the rear would have helped here...something on the wishlist for next year... as are the glowing brake discs [Image: innocent.gif] 

More diffuser follies...
Here are some more diffuser follies I dug up from my image folder. I'd almost forgotten about this one, and that while it was one of few occasions where I've been able to add scale detail...
...and improve the performance of a car in one go. So what are you looking at? Well, after our first test runs with the diffuser attached to the motor pod one of the team members wondered:
Wouldn't the added mass behind the real axle be ditrimental to the un sprung weight and performance of the car?
My initial reply was that on all the SW- short can cars we'd raced so far, the best set up had a bit of weight under the rear axle....but ok... let's see if we can make the diffuser lighter.
So I cut off the 0,7mm thick diffuser strakes and replaced them with very thin plastic cut from a booklet cover.
And behold even though it was but a 0,6 gr weight gain on a 2,5 gr diffuser..it did make a small difference...the cars was 0,05 sec faster... and it definitely looked much better...
..and as the strakes were now flexible...it improved the crash resistance as well. Absolutely loved it...but the time...and effort. You can understand why I modified only one diffuser like this.
 
[Image: post-18820-0-59196900-1566119438.jpg]

Ford GT LM Set-up : Control and adjustability of chassis, pod and body movement. 
Ok, enough talk about detail stuff, time to get down to the nuts and bolts of the car. Here's some more info on the technical side and the choices we made on the Ford's set-up.
Some slotracers look at a car and see the chassis as the part that makes the car go, and the body...well it needs to have a body right? But its mainly considered as dead weight. 
So let's get rid of that dead weight as much as possible...right? True a lot of time and effort has been made on the Ford bodies to make them light, not as light as possible but very close to the minimum.
But even if you do get down to the DiSCA min. 19,5 gram, that's not dead weight sitting idle on top of your chassis. That's weight you can use to make the chassis work...even better.


Take most 1/32nd slot cars out of their box and you''ll have a car were chassis, pod and body are screwed tightly together as one. As such any movement of the car will be transferred to all parts.
If the car leans in a corner it will do so as a whole, if the car rides a bump in the track it will do so as a whole. etc etc. On a plastic track, specifically a Ninco track..that's no good. 
In an optimum situation you would want all parts to be able to move independently and at the same time be able to control their movements and interaction independently.
Alas in most cases you'll have to settle for a compromise.
So first thing most will do is give the car some body and pod float, dump the horrible wood screws that will scrape inside the screw holders for a good set of half shaft metric ones...
...and your 3 components (body chassis & pod) can move independently. Loosen the body screws a few turns and you'll be able to control the amount of float, at least..upwards.
Where the body will rest on the chassis is often a different matter. Plastic tends to warp and bend as it gets loaded, some start to do so from the factory.
A lot of slot cars are designed in such a way that the body will rest on the chassis side skirts and front splitter. As such they will transfer the body weight to the chassis everywhere...
..and in most cases...no where in particular.

Body Supports
I prefer to have the body transfer its weight to the chassis on 4 points only. To have those points spread as wide apart between the axles and as close to the axles as possible.
So if on the stock car the body rests on the side skirts (as with the Ford) I will cut those off and glue them to the body. As such new body supports will have to be fabricated.
These are easy to make, just cut some pieces of think plastic rod or L shape, glue them in the body and cut them to the right size.  Which is basically what I did Ford the first Ford prototype chassis.
Later versions had a more controllable set-up with a holder for a grub screw incorporated on the chassis. The picture below shows how I glued the 3DP body supports into the body:
Tacked in place with some thick superglue and covered with neoprene glue to secure it in place, should the flex of body, during a crash break the rigid bond of the superglue.
My base set-up for almost all my cars is always to adjust the grubscrews so that the body rest squarely on 4 points evenly.
[Image: post-18820-0-69683900-1566119760.jpg]

C.o.G or Centre of Gravity
As a rule of thumb, you'll want it as low as possible. So remove material at the top of the body where possible, vacformed windows etc etc. all that stuff has been covered in my previous post.
Before we switched to the Ford as a plan B, I'd been working on the BMW M6, just one look at them side by side and you can easily tell which of the two had a lower C.o.G. 
The lower you're C.o.G the less prone the car will be to tip over on corner entry. And with the lightweight parts and body supports the Ford was rock solid in that area, better and more stable than the M6.
So you could carry more speed into the corner. But when we ran the two side by side, mid corner and on the corner exit it felt like the M6 had more grip [Image: blink.png] 
[Image: post-18820-0-35908800-1566122190.jpg]

Inertia & weight transfer
Now at this stage in testing the Ford needed balast in the body to get it on the 19,5 gr min weight, which we had placed low in the body. So it looked like we'd lowered the C.o.G too much?
Indeed we had, because when we moved some of the balast higher up in the body mid corner grip improved immediately, corner exit remained the same though.
When I checked the body after some test runs I also noticed we had more tyre deposit in the body than on the M6 and that the tyre wear on the Ford was higher.
We had to much wheel spin coming off the corner. So here's the last bit of set-up trickery we used to get more traction coming out of the corner.
We had cut the diffuser from the chassis and mounted it on the pod to solve the ground clearance issues.
We were running the Ford with a bit fair amount of body float to allow it to rock and use the weight transfer to load the chassis. 
But as there was now no more "chassis" behind the rear body supports, there was also no  contact point behind the body supports to transfer weight to the rear axle.
 
[Image: post-18820-0-35542400-1566119709.jpg]
Then I remembered how Nick de Wachter had used a big block of soft sponge mounted on the back of his Dome chassis to generate more grip.
During acceleration the body would tilt backwards and make soft contact with the sponge and via the sponge would transfer weight onto the rear of his chassis.
So I took a piece of foam rubber glued it on the diffuser where it would just clear the of the rear of the body.... and whoa, I now had much more grip coming of the corner.
(if you look close you'll be able to spot the first foam test set-up in the centre image at the bottom of this post  )
So the principle worked, all we needed now was a way to control and adjust the moment of transition.
As luck had it Stefan Nalbach had incorporated two body supports on the diffuser of his original chassis design. So all I had to do was glue two pieces of foam in the body directly above the supports.
I covered the foam with some sheet plastic to keep the grub screws from biting into the foam...et voila, we could now adjust the amount and timing fo the weight transfer under acceleration.

 
Ford GT LM Set-up: Lessons learned the hard way 
So here's the final bit on set-up, prior to Le Mans all our testing had been done on the permanent Suzuka track, which is a challenging track with chicanes, slow, medium and fast corners and a pretty decent straight.
To accustom ourselves to the longer gear ratios we run at Le Mans we used those in testing instead of the shorter ratios better suited for the Suzuka track.
From experience we knew that if a car set up like this ran well @ Suzuka it would also run well at Le Mans.
[Image: post-18820-0-63198800-1566121725.jpg]
During our testing we had run both SW chassis with different off set pods. Testing the slot.it 1,0 mm offset and 0,75 mm off set back to back. They were both fast, but the 0,75 was just a bit easier to drive.
It had more flow, it would roll easier into the corners. The 1,0 offset had better brakes, more aggressive acceleration but also needed more work to keep it flowing through the Esses.
Lennard and Nick (Helmich) were faster with the 1,0 offset, Marc and I were faster and more important more consistent with our laptimes with the 0,75.  
With Wayne and Stephen not being able to test run the car until we were in Henley, I was convinced  the 0,75 pod would be our best option.

[Image: post-18820-0-30984800-1566124361.png]
Well...I was wrong!!
This is written of course with the benefit of hindsight...and after having raced the Ford GT LM at Le Mans... and the Rock Bull ring, two very different tracks compared to Suzuka.
Not being able to concentrate on back to back testing of both offsets at Le Mans (caused by our controller problem) did not help, nor did the added stress of having to finish the lights on the race body etc etc.
But in all honesty, I just was not sharp, I wasn't on the ball, even though the signs were there. They say even a donkey does not fall in the same hole twice... but I did.
The previous year Ditslot I3D had run their Ford with a 1mm offset, and even though Stefan (Kievit) and Lennard had been faster with our Corvette (running a 0,75 mm offset) Ditslot had been more consistent. 
This year even after we finally got the Ford sorted and were running well, we were being outpaced on consistency by the Posillipo Ferrari... and the Prospeed Corvette. Both running bigger offsets than us.
Now I had no reference times for the Posillipo car, but Prospeed had tested their Corvette with us at Suzuka and even if you were to take in account the home track advantage...
...the Ford had been quite a bit faster. [Image: blink.png] 
[Image: post-18820-0-61937600-1566126041.png]
After Le Mans I did the usual post race inspection, found the chassis to be in perfect running order. During the race we did notice that we had much more wear on the right braid than on the left.
We had the issue on Sunday morning with the right front wheel binding and discovered that it had also worn down so much that the plastic rim was visible.
And even on the spare axle we fitted ( the chassis picture above was taken during the postface inspection) wear on the right was much more than on the left.
It wasn't until I took a real close look at the body (with just the windscreen wiper, a mirror and its left skirt missing) that I noticed that the right rear body support tab had come loose.
Loose as in being able to move up and down a bit, with just the neoprene glue keeping it fixed to the body.
Apparently the Ford had been hit hard on the left side, most likely at Mulsanne corner which took off the skirt (because that's were after the race I had found it).
This crash most likely worked loose the right rear body support. As a result the weight was transferred unevenly on the chassis. Uneven weight, uneven wear..but we made it to the finish.

After Le Mans my slot race focus shifted to the Oreca LMP1 prototype that we hoped to get ready for the e-csd 24hrs end of June, and when that was cancelled, shifted to the development of the LMP2 version ready for Rockingham.
During that time I took the Ford for a couple of test laps and immediately noticed that it had no brakes and no torque, even after changing to a gearing more suitable for Suzuka.
I put the car on the magnet Marshall and compared the values to what they had been pre Le Mans, yup, the motor magnets had been cooked by the long 15x28 gear ratio.

[Image: post-18820-0-61463100-1566120169.png]
Down Donkey, down
Time flew by and all of a sudden Rockingham was right on our doorstep, time to give the Ford a major once over. We'd raced at the Rock Bull ring last November, nice track.
Relatively flat (at least for a temporary track), medium length straights. One long straight with a tricky braking area with an LC smack in the middle of the brake zone.
Three sets of hand out tires for just 6hrs of racing.  With the lessons learned from Le Mans I had no intention of being a donkey again. 
So I decided to set-up  the chassis with the 1,0mm offset and a way shorter gear ratio, but no time for a quick test session @ Suzuka. 
Upon arrival at Rockingham the Ford ran well pretty much straight out of the box, even with the 1,0 offset it was easy to drive and had a nice flow through the corners. 
Stable and consistent more or less what we had experienced with the 0,75 pod @ Suzuka. [Image: question.gif] 
Still needed a bit more brake so dropped a tooth on the pinion. On pace the Ford was just as fast as the leading LM P2's and even matched the speed of most of the LM P1's.
Even our newest Danish team member John Anderson managed to put in some pretty decent lap times after he had become accustomed to a new track, a new car and a new very demanding team captain. [Image: thumbsup2.gif] 
We had to pit just two times for repairs, once after I'd hid a desolated car under the bridge at full speed: soldering on one of the light kit lead wires had broken.
And once as a precautionary repair as I'd noticed one of the side skirts had come loose after an other crash. This time I was on the ball.

Back home the post race inspection showed both body and chassis to be in good health no damage, even wear left right on the braids, the front and rear wheels.
We had used one set of N18 during the first 4 hrs with just 0,6 mm wear (0,15mm p/hr). Switched to the F22 for the last two hours and ran those down to 19,6mm, (0,5mm p/hr) [Image: yikes.gif]  
 
Horses for courses 
Two weeks ago I ran the Ford @ Suzuka again..and guess what... with the 1,0mm offset and same set-up, way to much brake, way to much and aggressive acceleration and hard to get a nice flow through the corners.  [Image: question.gif] 
And then it dawned on me, even though a car set up for Suzuka would run well on Le Mans and the Rock Bull ring there were similar differences between them and Suzuka.
 
1 Le Mans and the Rock bull ring are temporary tracks, and have less tyre deposit & thus less grip than the permanent Suzuka track.
2 The corners of the Le Mans and Rockbull tracks are flat or at least not banked in the way most corners are at Suzuka.
3 Besides banked corners the Suzuka track also has more undulations where the track rises and falls as it follows the terrain. As such it requires a bit more ground clearance.
The result of these 3 combined mean that @ Suzuka you need to run a smaller offset on your pod and with the higher grip levels can get away with a lower gear ratio.

So gents, mental note for Le Mans 2020 and all those who plan to take part in the Suzuka 6hrs...horses for courses gents, horses for courses[Image: wink.png] 

When the flag drops...the bullshit stops?
Time for some closing words on our 1/32nd Ford GT LM, its road to Le Mans...and then a bit more. Future projects are calling, a renewal of plan A.
But if there's one thing prepping testing and racing the Ford over the past six months has learned us... its always good to have a plan B.

For Ford running their LM GT had always been a 4 year project, winning Le Mans on its first outing and then Daytona, they had nothing left to prove.
Being caught out on the wrong side of the B.o.P several times didn't motivate them to extend the program nor do they seem to be interested in moving on to a Hyper car.
Their plan B of extending the life and success of the GT LM in the GT AM class was met with some peculiar and very strict regulatory measures by the ACO.

They say when the flag drops...the bullshit stops, while that may still be true if you cross the finish line winning (your class) in 1/32, but at Le Mans....[Image: unsure.png] 
[Image: post-18820-0-20453900-1566175402.jpg] 


With kind regards
Tamar

P.s: A big thank you to all who have helped me with this project,  special thanks to Simon Owen from Hornby for going the extra mile, providing us with spare cars..amongst one very special one.
Philippe Laudet for his outstanding Z-machine light kits.  Slotfabrik for the decals and C&C designs for the decal plan B.
And last but not least, a very warm thank you to Stefan Nalbach for the endless hours of work, redesigning the 3DP ProSpeed chassis  every time I would come up with yet an other modification.
[+] 2 members Like Tamar's post
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#22

Great stuff Tamar. That's quite a journey.
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