Haynes Front Suspension Improvements

[AshG]

After fitting my new engine i now have a fair bit more power to find the limits of the chassis (something i couldn't ever do with a 1.6 pinto). The suspension has been setup and the car drives very well through all manner of situations from high speed straights to long sweeping bends but there seems to be a little issue with tight cornering when pushing on a bit especially hair pin type bends.

I have noticed that in tight corners my front wheel that is on the outside of the corner (longer distance to travel) will squeel under load in the corner.

Now i spoke to martin keenan about this at stoneleigh and he admitted that the front end could be improved, since he designed the roadster back in 2006-7 he has got a lot better at using his cad packages and admitted that if he were to design the car again it would be with custom uprights at the front to get the geometry correct.

the thing that really spurred me on to investigate this further was that i spoke to tilly at stoneleigh and his roadster (blade engined) also does the same thing.

So is anyone up for having a go at investigating this further and seeing if we can come up with a solution to improve the setup?

[MarkB]

The solution has been sorted me old fruit gump;)

[AshG]

lets see it then? Was kind of hoping it could be a group effort

[MikeB]

Sounds interesting Ash.
its sounds like a ackerman angle/toe setting issue or scrub radius due to incorrect kingpin inclination. Did martin say what desirable geometry was?

Share all if there's a solution though, I'm a long way off driving mine though.

[MarkB]

When the boffin that knows the right words to use is available I will get him to explain but my word giddyness is about right even if sounds gobbledeegoook;)

[AshG]

well speaking to tilly if i can remember correctly he reckons its the roll centre that is too high causing positive and negative camber changes on tight cornering.

[MarkB]

well speaking to tilly if i can remember correctly he reckons its the roll centre that is too high causing positive and negative camber changes on tight cornering.

Goes mad positive in mental mode but it does it both ends Ash that's why it's not so noticeable when you are bumbling along.

[Tilly819]

hi all

almost ash, i did a bit of anylisis on the suspension on the roadster a few months back i will have to dig out my results when i get home, IIRC it was more to do with roll center movement and this had some effects that i cannot remember without my results, i do seem to remember that the camber curve was not too great and the outher wheel does like to push out to positve camber under heavy load i did remidie this on mine by running a large amount of statc negative camber but found not suprisingly that i was locking up the front wheels under heavy braking.

Il did out my results when i get home and maybe post a CAD drawing if i still have them.

Tilly

[Tilly819]

Goes mad positive in mental mode.

AGREED

I seem to recall quite abit of scrub during suspension travel also IIRC

tilly

[MarkB]

AGREED

I seem to recall quite abit of scrub during suspension travel also IIRC

tilly

Like I said best I wait for the boffin who knows the right words as I have my own words for stuff and will only confuse folk...but yeah you will be running off the rims when you push the car hard.

[mark]

I'm aware that the front geometry is probably not perfect but it also sounds like some under-steer being provoked by your new big power and the extra weight

Teesside autodrome track has some very tight corners and my car did have the front outer wheel screeching as you describe when really pushing on, a few trial and error damper adjustments made the world of difference

I found once i had dialled out the front wheel screech that the lack of an lsd was more of an issue anyway in hairpin type corners

An lsd is next on my "want to do list" and probably a stronger upgraded type 9

I think its incredibly difficult to set these cars up to a certain spec and then be happy with them, there is so many variables from car to car and every corner you drive around, i know you can set the fundamental things within a reasonable margin but nothing beats driving round a track like your hair is on fire then making some adjustments and doing it again :D

[AshG]

its only 30kg heavier than it was with the pinto it didnt even make a difference to the ride height and the fact that tillys bike engined one does it too shows its not a weight issue.

really need to model it properly to work it all out been tinkering in solid works but it takes me ages to draw things as i don't use it all the time.

also there isnt any harm in redesigning the wishbones and makeing a new upright to see if it can be improved, nothing ventured nothing gained and all that.

[les g]

Ash
please dont post a joke now
or you will end up banned
you know the rules
post jokes and be critical about the roadster and its.....
off to the naughty step for you......
lol
cheers les g
ps . i think your problem has been highlighted on here before

[minicountryman1961]

its only 30kg heavier than it was with the pinto it didnt even make a difference to the ride height and the fact that tillys bike engined one does it too shows its not a weight issue.

really need to model it properly to work it all out been tinkering in solid works but it takes me ages to draw things as i don't use it all the time.

also there isnt any harm in redesigning the wishbones and makeing a new upright to see if it can be improved, nothing ventured nothing gained and all that.


Have any here added a front and/or rear sway bar (anti-roll bar)? If so, what has been the effect on handling?

[Cyberbeej]

hopefully i can add to that data shortly as i have front and rear anti roll bars to fit.
Would be interested in what you guys com up with regarding the short falls of the sierra hub against a purpose made item.

Bought this book and it makes interesting reading.
http://cgi.ebay.co.uk/Build-and-Modify-Sportscar-and-Kitcar-Suspension-/170581084180?pt=Non_Fiction&hash=item27b76cc814

[martin62]

There was a Haynes Roadster on the Irish Kit Car Club stand at Stoneleigh that has anti roll bars front and back who races it at Mondello and also drives it on the road.I will try and get more details.

[MarkB]

Anti roll bar masks rather than cures the issue though.

[MarkB]

Scientific explanation to the issue in hand:















The hurdygurdy bits are going giddy into positive doodah causing the "kevin Shwantz all getting kinda squirrely" syndrome...

[minicountryman1961]

Scientific explanation to the issue in hand:
The hurdygurdy bits are going giddy into positive doodah causing the "kevin Shwantz all getting kinda squirrely" syndrome...

other than my Mini and Austin 1300, I can't think of any production cars I have owned that did not have a front sway bar as standard.

Lotus 7s had them, Caterhams & Sierras too.

[MarkB]

My old Locost never had an arb and also never under steered, was a tad tail happy though but that is what a rwd sports car is all about:D

[trick-kit]

As previously stated, in this case an ARB would just hide the problem with the geometry, the only way it would "cure" it would for the ARB to totally restrict the movement of the suspension, and you don't want that, anyone who driven a quick kart on a bumpy track will know what that feels like ;) (Eh Mark)

Personnally, I'm still biased towards the Cortina upright, yes it's not perfect, but I have done a lot of work with it and have a wishbone set up that keeps the wheel in check during roll.

So, I guess it will be an intersting read to see what people come up with. Come on guys, get the thoughts down.

TK

[minicountryman1961]

As previously stated, in this case an ARB would just hide the problem with the geometry, the only way it would "cure" it would for the ARB to totally restrict the movement of the suspension, and you don't want that, anyone who driven a quick kart on a bumpy track will know what that feels like ;) (Eh Mark)

Personally, I'm still biased towards the Cortina upright, yes it's not perfect, but I have done a lot of work with it and have a wishbone set up that keeps the wheel in check during roll.

So, I guess it will be an interesting read to see what people come up with. Come on guys, get the thoughts down.

TK

Mustang II/Pinto uprights are popular in the USA. You can see the specs for them here:

http://www.wilwood.com/Pdf/Flyers/fl193A.pdf

[les g]

why dont you just get hold of Fabbyglass
i think he has the solution already drawn up
cheers les g