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Re: Stub axle bearings by Slack Alice
20 October 2019, 08:01:54 pm

Re: Delage 15-S-8 by Marek.Z.N
20 October 2019, 05:59:55 pm

Re: Lessons Learned - Safety by Marek.Z.N
20 October 2019, 05:58:01 pm

Re: Delage 15-S-8 by Chris Brown
20 October 2019, 05:25:24 pm

Re: Electric drivetrain options by StefanN
20 October 2019, 03:10:33 pm

Re: Lessons Learned - Safety by RhysN
20 October 2019, 09:33:59 am

Re: Stub axle bearings by RhysN
20 October 2019, 09:33:01 am

Re: Lessons Learned - Safety by TheGiantTribble
20 October 2019, 09:05:04 am

Re: Delage 15-S-8 by Marek.Z.N
20 October 2019, 08:39:14 am

Stub axle bearings by Slack Alice
19 October 2019, 04:28:10 pm

Top Topics

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Bugatti Type 37 Build 1465 87
New build start..GN Thunderbug. 600 53
Morgan F build 655 44
CK 1 (ERA) build 575 43
Delage 15-S-8 610 36
Austin Ulster build 972 36
Competition time! 614 34
Stability 281 31
Wheels 484 31
Lessons Learned - Safety 214 29

Author Topic: Stability  (Read 281 times)

StefanN

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Re: Stability - checking castor
« Reply #15 on: 10 July 2019, 12:35:32 pm »
I needed to double check the caster on the Bugatti.  Not 100% accurate as without dismantling the kingpin I had to judge the angle by eye but the castor looks to be correct.

ChrisS

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Re: Stability
« Reply #16 on: 22 July 2019, 07:59:30 pm »
Hi Stefan, I've got some data re the ERA;

Wheelbase - 1665mm
Track front - 930mm
Track rear  - 920mm
Tip angle   - 57 degrees (pic taken at 55)
Overall weight  - 105.4kg
Front  - 35.4kg
Rear   - 70.0kg




StefanN

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Re: Stability
« Reply #17 on: 22 July 2019, 10:13:54 pm »
ooo the ERA is looking very nice.

Thanks for the numbers and photos Chris that's really helpful.  I put the picture of your CK alongside mine and made sure they were scaled to the same size and aligned using Powerpoint.   The Bugatti sits marginally higher because of the bigger tyres, but I'm sitting at least half a head higher than you.  We're not exactly the same height but even so that's quite a difference.   When I compare the ERA to the Bugatti with the new lower seat, we're sitting at about the same height.  I'm now desperate to get it onto a bit of tarmac somewhere to test it out and to see what difference it has made to handling.

ChrisS

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Re: Stability
« Reply #18 on: 23 July 2019, 08:17:23 am »
Yes it would be great to find some tame local tarmac for the occasional test and tweak between meetings, any ideas anyone?

RhysN

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Re: Stability
« Reply #19 on: 23 July 2019, 08:49:34 am »
I have gone and spoken with local industrial estates, NEVER mention race cars. Take something like the information flyer (Stefan has that) to give them a background.
I'm interested to know why the focus on tarmac though. These things are capable on all surfaces.

TheGiantTribble

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Re: Stability
« Reply #20 on: 23 July 2019, 09:51:23 am »
Re places you can try CK's. Locally I have

A neighbour has a padock I'm free to use.
Just down the road is a new building estate, weekends there is no building going on the site is empty, lots of flat tarmac and it's not officially a road yet :-)
School car park, unfortunatly our local High school looks their gates, they started this before I finished my CK so no blaiming Bill :-) But you might have better luck.
Local farmer, might not mind depending upon time of year...so not during lambing season
And lastly, get to know some of your local boy racers, they often use shopping centre car parks out of hours, now they might take the mik a bit, equally they
are petrol heads and will love the work that goes into a CK. And a lot used to be gokarters so the recognise and understand the clockwork we use.
I wont admit to driving mine on the road, but it was scary as hell, even passing a parked car you realise just how small and venerable these things are!


Ok back to posts about stability.

StefanN

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Re: Stability
« Reply #21 on: 23 July 2019, 10:20:27 am »
I'm interested to know why the focus on tarmac though.
For me a smooth surface will make it easier to observe what is happening on the CK without the added dimension of a random surface.  Once I'm happy with it on smooth then I might move onto rougher surfaces.

ChrisS

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Re: Stability
« Reply #22 on: 23 July 2019, 11:14:13 am »
Thanks for your suggestions guys, like Stefan, I think a smooth surface will be better for making subtle changes.

Chris Brown

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Re: Stability
« Reply #23 on: 23 July 2019, 11:58:35 am »
My view too tarmac makes it easier to judge how you're getting on with development. I can run mine around the perimeter of the paddock, but it's not big enough to get up any speed, nor is it either FLAT or LEVEL, not even in Welsh terms. As for our road, there's not much traffic, but it tends to be big tractors not hanging about. Knowing my luck I'd meet our six monthly police patrol.

RhysN

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Re: Stability
« Reply #24 on: 23 July 2019, 01:51:04 pm »
I get all the comments about getting some comparison, but as before, they are capable elsewhere and what works on tarmac might not be the solution elsewhere. Back in the days when vehicle dynamics and testing was a part of my life, the preferred surface was pea gravel on a hard surface. It shows the characteristics without having to have the speed.
Of course, if you make more than one change at a time, do you know which one was the one giving the outcome?

StefanN

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Re: Stability
« Reply #25 on: 02 September 2019, 10:46:04 pm »
So, without access to a test track, I committed the sin of making multiple changes at the same time to try and improve handling:


- I set the toe-in to about 5mm - it was about 15mm
- I moved the front leaf rear shackles to a nearly vertical position hoping to get a more even bend in the spring and hopefully less change in caster
- Lowered the driver position by about 100mm and moved pedals further to allow more space to straighten leg - both will have lowered the centre of gravity
- Played around with tyre pressures settling on 40psi at the back and 24psi at the front

Well between them, the handling was massively improved at Stretton and not at all sketchy in the way it had been.   My gut feel is that lowering the centre of gravity had the biggest impact followed by the tyre pressures.

RhysN

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Re: Stability
« Reply #26 on: 03 September 2019, 07:06:48 am »
for next time, can I suggest you try about 2 mm of toe in?

StefanN

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Re: Stability
« Reply #27 on: 03 September 2019, 08:39:18 am »
I can try....but
a) if I’m honest I don’t think I have that much precision in my set-up
b) contributing to a) is too much play in my yoke set-up.  I’m working on that.
c) why 2mm...on what basis?  What would I have noticed while driving at Stretton that would suggest 3mm too much toe-in?   I’m keen to learn.

RhysN

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Re: Stability
« Reply #28 on: 03 September 2019, 09:41:45 am »
Stefan, only reason it's a metric conversion as near as I can from lessons learned where imperial 1/8" was the best by most of the Gittreville.

StefanN

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Re: Stability
« Reply #29 on: 03 September 2019, 10:40:21 am »
Ah got it.  I rounded 1/8th (3.18mm) up to 5mm.   Once I sort the play I'll try bringing it in a little and see if I can feel a difference.  I've no idea even how stable it is - ie once I set it to 5mm does it stay they and are my measurements consistent.  Lots of to improve on here.