The Jaguar XJR-12 Group C I wanted in '91

[Pylon80]

Front Wheel Bearings

I somehow came up short by 2 ball bearings for the front wheels so I considered using the kit bronze bushings.

And, well, I think these are really cool! They are what people would use back when ball bearings were only available from Germany/France/Japan and would cost a fortune. So I gave them a try and they do feel very smooth. They are made of some sort of sintered bronze material and are "self lubricating" when used in contact with the steel knuckles. I did use a drop of bicycle chain oil which makes them smoother. I think if I can be bothered with having to wipe them clean and re-oil after every run they would last a very long time. On a touring car that has almost 20 bearings you certainly want proper ball bearings but I an not exactly worried about the front wheel of a pan car; it will be fast and zippy even with the bronze bushings. Interestingly when cornering they rub against the wheel nut, unlike a ball bearing on which the inner ring is stationary. For that reason I'll stick with the kit steel lock nuts.

Tires

The tires are "glued" to the wheels using the kit's double sided tape. I had to pull really hard on the backing film. The Tamiya tape has a really strong backing that won't tear, but I would be worried about trying it with my transfer tape which has a very thin papery backing. I would totally see how it would tear off halfway through the job 😐

So I'll have to think whether I want to source more Tamiya tape or not when the time comes to replace the foams.

As I have mentioned before (I think) the wheels are much wider than the tires which our @TurnipJF explained was meant as a tuning option: one can adjust the track width of the car by gluing the tires more inboard or more outboard. As a starting point, I just thought it would look much nicer if I glued the tires as far outboard as possible.

[Pylon80]

A few pictures with the body on, but the wing still a WIP. It's gorgeous. After wanting this for so many years I am pretty stoked.

Caption: Would you run it or just leave it on a shelf? Exactly.

[ThunderDragonCy]

@Pylon80 That. Looks. INCREDIBLE

[GermanTA03Guy]

Ultrasweet.

[TurnipJF]

That looks awesome! Great job!

[svenb]

Does look good, have you a set of the original wheels?

The black still looks nice though 

[Pylon80]

1 minute ago, svenb said:

Does look good, have you a set of the original wheels?

The black still looks nice though 

I do not. But then I am not a huge stickler for assembling things with the original kit parts all the time. The rear ones are moot to me since they are invisible with the body on. The front ones I am on the fence. The black ones are not 'correct' but they are also very simple and being black also helps minimize the visual hassle.

[Ferruz]

I just spent the last couple hours reading through the thread from the start, and enjoyed every bit of it. top work all the way! Fantastic build 😎👍

Loved the side monstruosities chopping spree, the attention to details and the end results of the white plastics phobia 👌

Looking forward to the roll damper installation. 

[Pylon80]

22 minutes ago, Ferruz said:

I just spent the last couple hours reading through the thread from the start, and enjoyed every bit of it. top work all the way! Fantastic build 😎👍

Loved the side monstruosities chopping spree, the attention to details and the end results of the white plastics phobia 👌

Looking forward to the roll damper installation. 

Thank you Ferruz, I really enjoy documenting my tinkering so that I may have something to look back to. If this thread has entertainment value for my fellow TC members then it's simply awesome 😎

[Re-Bugged]

Looking sweet as a nut @Pylon80 👍🏻

Should you run it?? Yes in a very large open area with not so much as a small stone for at least a 1 mile radius 😉

[Pylon80]

6 hours ago, Re-Bugged said:

Looking sweet as a nut @Pylon80 👍🏻

Should you run it?? Yes in a very large open area with not so much as a small stone for at least a 1 mile radius 😉

It can be made to ride as high as 10mm so it's really not any different than a touring car in that respect. However the body is rare enough that indeed I wouldn't run it anywhere close to curbs or obstacles!

[Nick G]

Looks stunning ! 

[Pylon80]

Mini update, live from the dunny.

Roll Damper Part One

After running the car in stock form i.e. without the roll dampers I found that the adjustment of the t-bar screw (aka the o-ring squashing screw) has to be a compromise, as usual: too tight and the car under steers (boring!) but too loose and the car becomes unstable and the rear can be knocked loose if you're not really gentle with your steering inputs (annoying!). The roll dampers help in that respect, allowing a somewhat looser setting of the infamous screw for sharper cornering without loosing the rear.

The first step was to choose some dampers. I wanted them simple, light and black 😬 so I bought the same ones I used to have on my Roche F1 Evo:

These are friction dampers and commonplace in F1 and pan car racing. I use Tamiya friction damper grease in these. You have to wipe them clean very often as they obviously attract dirt but they work extremely well for their simplicity and almost negligible weight.

The Group C bathtub has some convenient alternate body posts locations that are not used with the Jag body. These have an hex recess shape which happens to match the Square RC body posts that I found in my stash.

I started by cutting them to only keep the bases:

Then I sanded them flat and neat:

Now, the annoying part is that the hex is oriented in such a way that it's an edge rather than a flat that faces aft. If I am to attach a damper to that hex I must drill a hole right on that edge! So I sanded a very subtle flat and then pointed a hole with the point of my dividers:

(look closely, there's a hole there!)

Then, holding the hex between two pieces of wood I drilled a hole with my trusty drill press:

I found a 2.6mm diameter bit that is a great choice for drilling a hole in plastic that is going to be tapped to M3:

The next picture has a worn adjuster and ball nut for fitment purposes only:

 

Next up will be the attachment of the inner part of the dampers to the pod.

[Pylon80]

Roll Damper Part Two

This is what each damper looks like with the hardware ready to go:

I chose the grey "low friction" adjusters as I found the black ones to develop an annoying squeak very quickly in the dusty conditions I drive my cars here.

I then measured what a good distance would be between the two inboard adjusters; 22mm it was.

Then I used some 2D printing to make the bracket that will enable the dampers to attach to the pod.

The styrene I use is only 1mm thick and it's worth mentioning that the loads involved when the damper moves are miniscule. We're nowhere near what it would take to make the part buckle, and I also want to minimize the weight being added to the pod.

Sanded and ready to go:

 

I then drilled the pod to attach the bracket:

The lower holes will use tiny M2 tapers from my 1:27 parts box while the upper holes will use aluminum screws I find in my stash (wrong blue but at least they're aluminum).

And this is what it looks like one installed:

It's always wonderful when you imagine a modification (even something as simple and straightforward as this...) and then see it take shape and think "ah, so that's what it looks like!" 😎

Next up will be some ramblings about the body posts and some pictures of how I fit the shorty pack.

[skom25]

Are you sure that 1 mm styrene in stiff enough? I found that it is very flexible and rather soft.

[Pylon80]

1 hour ago, skom25 said:

Are you sure that 1 mm styrene in stiff enough? I found that it is very flexible and rather soft.

It's many times stronger than it needs to be as far as the dampers' loads are concerned. Even 0.5mm styrene would be enough for the dampers. so I chose the thickness more out of concern for the risk of breaking the part while working on the car, as well as the general "perceived strength" rather than any real concern of the part buckling while running the car. Now, if I were driving around other cars and getting frequently rear-ended - which is not the case - then yes I imagine the part could snap in a big crash.

[Pylon80]

Micro-Update:

Last night I finally tried the Group C with the Formula Tuned motor. I was able to retain the stock spur and simply moved up to the largest pinion that would fit (16t).

As expected that motor is very smooth being 32 turns and to my surprise the car still covers a surprising amount of space in very little time 😅

I will have to find a way to make this motor rebuildable. For starters I can always drop the rotor inside the TZ "can" and just retime it to match the FT timing. But a solution that would keep all the FT parts would really be awesome. I have a few ideas knocking (or rather, sloshing) around the back of my head, in the RC section 😵‍💫

[TurnipJF]

On 3/21/2024 at 5:05 PM, Pylon80 said:

Roll Damper Part Two

This is what each damper looks like with the hardware ready to go:

I chose the grey "low friction" adjusters as I found the black ones to develop an annoying squeak very quickly in the dusty conditions I drive my cars here.

I then measured what a good distance would be between the two inboard adjusters; 22mm it was.

Then I used some 2D printing to make the bracket that will enable the dampers to attach to the pod.

The styrene I use is only 1mm thick and it's worth mentioning that the loads involved when the damper moves are miniscule. We're nowhere near what it would take to make the part buckle, and I also want to minimize the weight being added to the pod.

Sanded and ready to go:

 

I then drilled the pod to attach the bracket:

The lower holes will use tiny M2 tapers from my 1:27 parts box while the upper holes will use aluminum screws I find in my stash (wrong blue but at least they're aluminum).

And this is what it looks like one installed:

It's always wonderful when you imagine a modification (even something as simple and straightforward as this...) and then see it take shape and think "ah, so that's what it looks like!" 😎

Next up will be some ramblings about the body posts and some pictures of how I fit the shorty pack.

A neat and tidy solution. I like it!

[Andreas W]

On 3/17/2024 at 7:13 PM, Pylon80 said:

A few pictures with the body on, but the wing still a WIP. It's gorgeous. After wanting this for so many years I am pretty stoked.

Caption: Would you run it or just leave it on a shelf? Exactly.

That's an urter beautiful car. I don't know how I have come to it, but I have seen it for me in the Silk Cut livery,  as I was used to see it on Sky Channel in the early 90s. The Castrol livery is somewhat different and suits the mean looking shell like a glove as well. Like Ferruz' car this is also astonishing real looking. This will be fun to run in the Endurance Postal Racing  and I very much is looking forward to see how it goes. 

[GermanTA03Guy]

The shell is really special, but what is underrated is hiw beautiful a plastic tub can be. I really dig the Look of the chassis, especially now with the mods. Your whole project makes me dream about owning one of these. As cool the Castrol shell is though, for me it has to be silk cut in any color way they ran bitd. Also childhood memories from TV..... how does the hobbywing 1080 behave in a race car ? I  Fancy that esc over the 1060 but it confuses me that its always titled as a crawler esc (whatever that means) ... 

[wtcc5]

@Pylon80: Sensational! So nice looking and I guess with that rear damper hop-up, very fast too. Great work! Exactly what R/C should be.

[Pylon80]

9 hours ago, GermanTA03Guy said:

The shell is really special, but what is underrated is hiw beautiful a plastic tub can be. I really dig the Look of the chassis, especially now with the mods. Your whole project makes me dream about owning one of these. As cool the Castrol shell is though, for me it has to be silk cut in any color way they ran bitd. Also childhood memories from TV..... how does the hobbywing 1080 behave in a race car ? I  Fancy that esc over the 1060 but it confuses me that its always titled as a crawler esc (whatever that means) ... 

Thank you for the kind words regarding the chassis. As for the body, I have no merit as this was a Tamiya "factory finished" I believe

The 1080 is an amazing value for a "real" ESC (as opposed to a lame copy of a branded ESC, buy-3-return-2-of-them kind of job). I think I have figured out the settings now; I made a post about it on the All Things Electric forum. HW made it confusing at best. The key to use it for on-road is to set the "freewheeling" in reverse of what your common sense tells you... sigh... so to enable the freewheeling you have to set it to "disable". Sounds crazy but I tried that in utter frustration when I first got it and it started working perfectly after that. Then the initial starting forces for both forward and reverse is best set to 1 i.e. disabled, as this is really a crawling function. Then everything else is conventional and it does work great. The biggest improvement for me over a 1060 is the ability to choose your cutting frequency. Higher frequency will give you more finesse which is a great thing for any RWD car. Also it makes a really awesome (if subjective) chirping noise when you apply power and when you hit the brakes that I find really pleasant. Hitting the brakes kind of sounds like a the waste gate of a turbo letting off  You have to try it to understand what I mean, but it keeps me grinning from ear to ear every time.

[TurnipJF]

I am really enjoying seeing people's different takes on the Group C chassis. Of the four recent builds documented here, three of us have fitted roll dampers, each coming up with a neat, different and unique way of doing it.

I look forward to seeing your solution for the cooling fan mounting. 👍

[chris.alex]

This is really an impressively beautiful work. And nicely presented! 👌

[GToddC5]

On 2/6/2024 at 12:15 AM, Pylon80 said:

. . .

Quiz

While I am it and in case anyone is still reading, I thought I would ask if anyone knows what these multiple monstrous protrusions and holes are meant for on part A5:

I thought maybe a transponder mount? Antenna mount is already on the tub. What else?! All inputs welcomed before I saw, chip, sand and polish all of these into nothingness! 😬

 

(Not so) Mystery solved, thanks to the arrival of my recent Daytona Thunder score!