Cars Jaguar XJ13 1967 W.I.P.

[aphidgod]

From the RL test driver, in his own words:

Hobbs Yeah. It gave quite a lot of horsepower. It went extremely fast. We went to MIRA about four or five times. Sir William came once .. Mr Heynes used to watch it. Then they made the decision to drive it at Silverstone so they decided to get two drivers – me and Richard Attwood, another apprentice. So off we go to Silverstone and I can’t remember the exact times but I think we did round about a 1:36 – 1:35 – 1:36. [1:35.7 -ag] The lap record at the time was help by Paul Hawkins in his red GT40 – about 32 or 33. So we weren’t all that far off the pace. If you consider it had these old pads, old wheels, old brakes. The suspension flexed far too much of course. And of course it had no attempt at any sort of spoilers on it. Very sleek. It was incredibly quick of course down the straights.

Richard and I gave a job list of things to do. We wanted wider tyres – we wanted modern wide wheels for a start and modern racing tyres. I think those two alone would have seen us down to the lap record. And another … I seem to remember the bias front to rear brakes was poor. It wanted a lot of, you know, a good tidying up. We reckoned it would have been quick.

...

But I really think the car would have been an absolute wow. I mean, at Le Mans, the thing would have had it. Because the GT40 in those days was an iron-block Ford that was only giving about 300 brake horsepower. I mean, this thing gave nearly 200 horsepower more than the GT40. There’s no doubt about it, it wouldn’t have been as quick as the Mark 2s, which of course raced in ’67. But it would have been very fast and, just by updating it, cos I’m sure it had been sitting in the shop for a couple of years – just by updating it.

But they had a problem. You’ve got to use Firestone or Goodyear racing tyres for example … Dunlop weren’t making good racing tyres then … for that type of stuff

There was also a mechanical issue in the rear suspension which caused an unstable camber condition under lateral load, mentioned in the test report but not this interview.

For AC we've granted David his request and put on the wider wheels and tires although they're still meant to be the lesser Dunlops. We improved the brake power/durability issues but left the bias at 61%F as that's what the book says is in the real thing. And we fixed the camber problem at the rear because, well, there's no way to simulate that in AC anyway. And now it does Silverstone 67 in the 33s, so...

I've been through the suspension design today and the roll centers had indeed migrated, although not as far as I'd thought. (1mmF/5mmR) Fixed that, fixed a couple other things I found along the way. Looks like I failed to take that step last time I adjusted the rear suspension... front was basically ok.

 

[mantasisg]

Ohh... I guess I had too much work today :/ Then everything is logical haha I usually know what brake bias percents stand for lol

 

[Willy Wale]

I've not driven the real thing (surprise) but when I tried your mod it behaved roughly as I thought it would. I know AC is a game but most of the cars are too sanitised. A high performance road car with all the modern electronics will chuck you in a ditch if you take the piss, a race car will laugh at you while doing it

 

[Darth mong]

Well, time to get the wheel out again i suppose... ;D

Been waiting for an update for a long, long time as the car was pretty much uncontrollable under braking for me.

 

[mantasisg]

@Darth mong I don't think you'll find it better now. The issue with bumpsteer was eliminated, so it is more predictable now, however there are still quite a lot of engine braking torque, so you either brake mostly in straight lines and rev match properly, or have some feathering throttle inputs through the corners while coasting to compensate engine braking.

Or don't go faster than you can

 

[Darth mong]

I've always braked in straight lines and rev matched anyway, just for some reason it would snap left even at half brake application. Was rather weird but i'll see how it is now

 

[mclarenf1papa]

From the RL test driver, in his own words:


There was also a mechanical issue in the rear suspension which caused an unstable camber condition under lateral load, mentioned in the test report but not this interview.

For AC we've granted David his request and put on the wider wheels and tires although they're still meant to be the lesser Dunlops. We improved the brake power/durability issues but left the bias at 61%F as that's what the book says is in the real thing. And we fixed the camber problem at the rear because, well, there's no way to simulate that in AC anyway. And now it does Silverstone 67 in the 33s, so...

I've been through the suspension design today and the roll centers had indeed migrated, although not as far as I'd thought. (1mmF/5mmR) Fixed that, fixed a couple other things I found along the way. Looks like I failed to take that step last time I adjusted the rear suspension... front was basically ok.

How does the book define the brake bias (i.e. In what context is it mentioned)? Also does the car have different front and rear discs/calipers or are they the same?

 

[aphidgod]

Nope, same discs and calipers front and rear. The split of the hydraulic proportioning valve was given in the book in a section that talked about various setup changes that were tested. (They tried one other valve iirc and settled on this one.)

I know it's not an ideal bias but that was confirmed by Hobbs as being the case, I think.

 

[mclarenf1papa]

Nope, same discs and calipers front and rear. The split of the hydraulic proportioning valve was given in the book in a section that talked about various setup changes that were tested. (They tried one other valve iirc and settled on this one.)

I know it's not an ideal bias but that was confirmed by Hobbs as being the case, I think.

All good then. If the discs or calipers were different you'd need to know piston sizes and the like to calculate the actual torque bias for AC.

 

[aphidgod]

Yep... I'm fairly sure that info is also in the book, though not needed.

With the corrected geometry it's a lot less twitchy under braking. Mantas is borderline mad at me for neutering it. We'll get it sorted.

 

[Emery]

I finally realized what the inertia reminded me of: a 2nd generation Toyota MR-2. An evil handling 2nd generation MR-2 in regards to the braking . Of all the mid-engine cars I've driven, it was the most tail-heavy when it came to inertia and still it didn't misbehave as badly as the XJ13 currently does under braking.

I fiddled a lot with shock settings to try and slow down that wicked weight transfer. Some success, but it still bites me more than the aforementioned MR-2.

For reference, my real life mid-engine racing experiences include:
Fiat X-1/9 in stock, street enhanced, & full race trim with slicks
Lancia Scorpion (aka Lancia Monte Carlo) in stock & street enhanced trim
Lotus Europa in full race trim with slicks
Toyota MR-2 1st generation in stock & street enhanced trim
Toyota MR-2 2nd generation normally aspirated & turbo in stock trim
Pontiac Fiero in stock & full race trim V8 with slicks

 

[Seria17hri11er]

For reference, my real life mid-engine racing experiences include:
Fiat X-1/9 in stock, street enhanced, & full race trim with slicks
Lancia Scorpion (aka Lancia Monte Carlo) in stock & street enhanced trim
Lotus Europa in full race trim with slicks
Toyota MR-2 1st generation in stock & street enhanced trim
Toyota MR-2 2nd generation normally aspirated & turbo in stock trim
Pontiac Fiero in stock & full race trim V8 with slicks

Dope! I'm jealous. And, a Fiero with a V8?! Haha, I bet that was wicked.

 

[Tibor Solyom]

I couldn't try the update yet, but I really loved the last version. When I drove the GT40 and the Cobra after the Jag I always had that bad feeling, AC is too forgiving. I can't imagine they were so easy to drive, I feel like they have stability control on. So don't make it easier please!
One of the very best cars IMO.

 

[mantasisg]

I think AC cars are in the shape how they are disgned to be. But the truth is that nothing in real life is ideal, I guess it might be that some joint might be offset a few mm because of little errors of car constructors, or because cars deforms and wears a little during their lifetime. It might be only milimeters. And right now Aphidgod did a few corrections, and, in fact it is milimeters.

Honestly, I just don't understand people, I really don't have too much trouble with that car, certainly not more than for example with Cobra, F40 or Lotus 25.... I think it is natural that someone doesn't like some car. I remember Henri from Aloog hating tuned RX7, and i love that car, and Henri is a very good driver....

I don't know when and how the update will arrive, Jaguar will always be demanding to drive, no other way, but it can be a little more calm. I'd like it to be a little crazy, we'll see how it will be. Aphidgod certainly knows a few fixes. I wouldn't fix it at all, or just slightly.

 

[mantasisg]

This is most appreciated update so far, and I'm really happy about it. Having an article on the main page dedicated to the car was absolutely amazing. I must thank @Seria17hri11er for this iniciative to have an article and amzing video that he created, it was super nice from him, he did all the management

I want to share his video, once again:

After all opinions and appreciation of people like him is what really matters, not someone who tries the content for a few minutes just out of boredom

For the true people !

 

[Fat-Alfie]

Has this been mentioned? (sorry, if it has )

 

[mantasisg]

Yop it was. I have removed LODs for this version, but forgot to change the value when LOD_A goes off :/

I shouldn't have released this S1 version, and I did the tweaks for it, not aphidgod. But aphidgod did the physics for it today, and it is mad ! Mostly because of skinny rear tires I guess. Enough to make every noob go mad, and give me more three stars reviews lol

I can not wait for more of them

Are you going to create a thread for the Feldbergring ? It is rather crazy track.

 

[Fat-Alfie]

I really like the S1 version, even with its 'speederbike' missing LOD driver madness

Ignore the 3 star reviews

I'm not sure I will bother with a WIP thread for the Feldbergring. I found it rather exhausting for Thomson Road, and all the techniques I used / learned for TR will be applicable for Feldbergring, so no real point in reinventing the wheel (except for my gorgeous cobbled road physics )

 

[Kasti]

Can`t believe what some guys rated and their strange reasons why.
When driving it the 60ies style, I have no problems with it, it works simply in its times technical limitations. And what means "too loud"? Can this wonderfull engine be to loud? Of course not.
I agree to Fat-Alfie - ignore those 3 star reviews.

 

[mantasisg]

@Kasti Yeah, I never expected three stars, which means that mod is barely usable. And the car is very drivable, if you are classy enough with it

Those guys definitelly aren't worth attention, but I always get a bit angry when I see any other mod getting such unobjective reviews. Like getting a bad review because you made the track bumpy, and it is bumpy IRL, or you made 50s car very floaty, and then get bad reviews because it is floaty, or made a loud car loud, and getting a bad reviews for it being either too loud for someone, or not loud enough for somebody else...

But I guess every mod suffers from one, or another troll, so it shouldn't make difference.