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MK chassis design

andrews_45 - 15/12/06 at 11:52 PM

Right then... I have some minor problems with my car, that could have drastic effects on my handling.

I have took my car to a race car company, to have some base settings done. I got a call from them to say I have zero castor on the front end set up and my car wouldnt handle on a track as it is.

Ok, I thought... No problems I'll just call MK and explain the mistake, who assured me that no locost race cars have any castor and it is how they are designed.

NOW!!!! I could be wrong, and left to eat humble pie.!! But it seems to me that my car has a inherent in-built design problem, can anybody pursuade me different. I did suggest to MK that they could exchange my top wishbones for a set with the correct castor i.e 5 deg positive (or is that negative, i always get confused), but I was assured that me, and a experienced race set up company are wrong...

Who do I listen to??

Help and advice pls

Pls note: I have zero issues with MK and have found them a very helpful company in past experience, I just do not think they are right in this case

Andy S - 16/12/06 at 12:14 AM

I would agree with your race car company that zero would be a particularly bad thing - 5-7 degrees in my book.

We know that the book has an error with the top wishbones but I dont think that even Ron is that far out.

Zero would give some very strange feeling

Perhaps give MK the benefit of the doubt that they got the wrong end of the conversation and ask them again.

Cheers

Andrew

[Edited on 16/12/06 by Andy S]

pawgrp - 16/12/06 at 08:01 AM

talk to martin keenan at mk eng, he made the jigs and he will be able to explain. hope this helps.

oliwb - 16/12/06 at 08:24 AM

&'s always have problems with castor (I say problems because its only really a problem with self centering and SVA not handling.) I don't honestly know what my CAT is setup to but it handles like nothing else.....I was thrashing a 911 Carrera in some twisties the other day with it no sweat (got wasted on the straights - obviously!) I'm not really much of a boffin when it comes to handling geomoetry etc but I imagine that your MK wont be any different to the others (all made on jigs) so if no one else has a problem with castor and handling it makes sense that you wont either. Obviously I could be wrong.....don't MK use those mushrooms in the front uprights that can be rotated to induce castor? Have you set them up right?? Also whats the car ultimately for? If its going to be SVA'd I wouldn't spend too much time setting it up now as you'll lose all your settings making it self centre properly and various other bits and bobs for SVA. Obviously if its not going to be used on track after SVA then I would suggest that a race garage are not the best ppl to setup a road car as they don't usually take into consideration things like bump steer etc....some food for thought....Oli.

britishtrident - 16/12/06 at 09:30 AM

The most important thing about caster is to get both sides exactly equal when the suspension is in its normal static loaded condition otherwise the steering will pull.

Caster is a complex subject, in the days of high profile cross-ply tyres a lot was needed especially on cars that were light at the front, with modern tyres much less is needed.
The ammount of caster used is also closely connected to king pin inclination and camber angles. In old cars used a lot of caster linked to a lot of kpi and a quite a lot of posative camber.

The Cortina upright (and the Sierra based upright) has very little caster designed in. With the Cortina upright use a lot of caster and you will end up too much negative camber in turns.

MK set thier cars up with a fair bit of negative camber, if you increase the caster angle you may find this has to be reduced and this may have other effects.

Also remember ride height trim front to rear has a big effect on caster ---- raising the rear ride height car relative to the front decreases caster.

***** How often do I have to repeat this point ******
***** Rotating the mushroom won't alter the Caster angle *****

However it will alter the king pin inclination if the same camber angle is set.

On the good side caster gives better self-centering and road feel.
On the bad side Caster increases bump & roll steer and also loads up the steering in turns and increases tramlining.

andrews_45 - 16/12/06 at 09:51 AM

No mushroom on my car, its a locost race car. I told MK what it was for when I ordered it. I have got to use Cortina uprights as per the locost race regs.

flange nut - 16/12/06 at 10:09 AM

This could be a stupid suggestion but could you have the top wishbones on upside down?

TimC - 16/12/06 at 10:25 AM

0121 3503258

He'll put you right.

Hellfire - 16/12/06 at 10:26 AM

Is it an Indy you're talking about? Are you sure your wishbones are on the right way? Reason I ask, is because the MK wishbones do have castor.

Phil

britishtrident - 16/12/06 at 10:53 AM

quote:
Originally posted by Hellfire
Is it an Indy you're talking about? Are you sure your wishbones are on the right way? Reason I ask, is because the MK wishbones do have castor.

Phil

Good point

TimC - 16/12/06 at 10:57 AM

quote:
Originally posted by britishtrident

quote:
Originally posted by Hellfire
Is it an Indy you're talking about? Are you sure your wishbones are on the right way? Reason I ask, is because the MK wishbones do have castor.

Phil

Good point

Except that it's not an Indy - it's a 750MC Locost.

andrews_45 - 16/12/06 at 01:18 PM

I can confirm that they are the right way round. MK said that they are jig made and none of the locost race cars have any castor

D Beddows - 16/12/06 at 05:35 PM

Vote number 2 for phoning Matt at Procomp

Andy S - 16/12/06 at 06:44 PM

quote:
Originally posted by andrews_45
I can confirm that they are the right way round. MK said that they are jig made and none of the locost race cars have any castor

Not great reasoning - are they able to give a better technical explanation as to why they think that the geometry works better that way?

Andrew

D Beddows - 16/12/06 at 07:15 PM

Probably for similar technical reasons to not designing them to be strong enough either

procomp - 16/12/06 at 07:21 PM

Hi just about sums up MK's attitude. All the other manufacturers of chassis for the locost championship certinaly DO have castor on them.

cheers matt

procomp - 16/12/06 at 10:07 PM

Hi posted reply in the race isues section.

cheers matt

procomp - 16/12/06 at 10:20 PM

Hi And you honestly BELIVE every thing you read in the kit magazines.

Maybe all the race driver that have had Mk chassis must be wrong about the handeling problems with thier wishbones and Zero castor then.

I still cant see what you are trying to say as Mk have said that they are jigged for Zero castor and that is what they have got .

cheers matt

Hellfire - 16/12/06 at 10:23 PM

Charlie, I don't think anyone's questioning the amount of caster on the Indy wishbones. Don't know if the MK Locost ones are manufactured to the same dimensions though but from other threads, it would appear not.

Phil

procomp - 16/12/06 at 10:29 PM

Hi i dont think that i am degrading them they are the ones that have admitted to running cars with no castor.

They are also the ones that LIED by telling thier customer that all locost race cars have zero castor so accept it .

All of the other manufacturers actually do have castor on them.

cheers mat

procomp - 16/12/06 at 10:41 PM

Hi is the Mk sprint allowed in to any of the race championships that we race in.

Is it allowed in to the FIA historics.

Is it allowed in to the barc westfield race serise.

Is it allowed in to any of the 750mc championships .

cheers matt

procomp - 16/12/06 at 10:56 PM

Hi i hope they handel better than the one in the 750 kit championship.

Anyhow slightly off the topic off castor.

Off to bed cheers matt

Hellfire - 16/12/06 at 11:19 PM

Could these posts possibly explain why the vehicle in question has no castor??

It would appear that the wishbone brackets may have been moved and re-welded??

This post

And the post below would suggest Luego wishbones have been used, or is this not the case??

This post

I'm not trying to stir things up, just trying to figure out why there's no castor but it would appear that MK may not be the ones to blame...................

Phil

[Edited on 16-12-06 by Hellfire]

Hellfire - 16/12/06 at 11:29 PM

Also notice that the lower bracket at the rear has been repositioned and re-welded

Phil

Hellfire - 16/12/06 at 11:34 PM

Hang on a minute.......... The race car company that is setting the car up for you is Procomp isn't it??

Like Charlie said earlier, and after looking at some of Matts historic posts, he clearly seems to have issues with MK for whatever reason..........

Phil

DEAN C. - 16/12/06 at 11:34 PM

quote:

Hi is the Mk sprint allowed in to any of the race championships that we race in.

MMmm!
Think someone is getting their companies mixed up,as the sprint is made by Martin (MK engineering),this subject is to to with MK sportscars I thought??

Perhaps the slagging off other companies first before you realise all the facts is ok with some but it smacks of petty bitching to me,not very profesional is it.

I have'nt seen the car or wishbones so i'll refrain from commenting!!perhaps others shouldn't shoot from the hip too!

john_p_b - 16/12/06 at 11:37 PM

if the above last few statements are correct and the wishbones aren't actually mk items and therefore non of this is actually mk sportscars fault then i do hope procomp will be issuing a full appology to mk.

however if the above last few statements turn out to be incorrect then please feel free to ignore this post

andrews_45 - 16/12/06 at 11:39 PM

Wooooaa!!! there chaps, this appears to be getting well off topic. In terms of moving the bracket in question, no mountings have been moved, the bottom ones have been widened on one mount to allow the bottom wishbones to fit in. The picture in question was me trying to offer up a old pair of Luego ones that I got off ebay. The suspension geometry has not altered since it left the MK factory on 30/03/06, It also has Mk Locost wishbones fitted.

Back to my original point, I was trying to acertain why my suspension has zero castor and if it is correct. Any research that I have found states that I need some incorporated castor, whereas MK say I dont. The reason why I need to sort it out now is because you cannot use adjustable top wishbones in the 750mc race series.

This then leaves me with two options...

1) My Locost race car will not need the castor - I leave everything as it is
2)I change the top wishbones to accomodate the castor.

The only thing that makes me think it might be an inbuilt design issue is when I hear of other people having difficulty with self centering on their cars (a quirk of poorly set up castor).

And yes I was told on the phone that none of the Locost race cars have the castor

Hellfire - 16/12/06 at 11:46 PM

quote:
Originally posted by andrews_45
Wooooaa!!! there chaps, this appears to be getting well off topic. In terms of moving the bracket in question, no mountings have been moved............. The suspension geometry has not altered since it left the MK factory on 30/03/06.........

So what happened here????

Phil

DEAN C. - 16/12/06 at 11:49 PM

I dont think anyone has thought that you were causing a fuss! someone else has done that!

Does seem strange that no castor is built in though.

I would think you might be as well clarifying things with Martin himself at MK engineering who was responsible for building some of the early cars for Ron Champion.He will know if the castor was built in or not,althogh obviously Martin does not run MK sportcars now.

andrews_45 - 17/12/06 at 12:12 AM

Right, this is going in a tangent. Back to my original point. As I have said this is a 750mc Locost race car.

Initially I had a set of Luego bones and the 'rear' bottom wishbones mounts were replaced with wider ones that would accomodate the Luego bones.

The front mount has NOT been moved and has stayed in the same position, the rear mount has been replaced with a wider one that would allow the luego bones to fit in. Therefore the suspension geometry has remained EXACTLY the same and not altered from how it was on day one.

Fitted now is a set of MK locost wishbones utilising 3 of the original mounts and one wider one (to accomodate the Luego ones), as you can see that the geometry remains identical.

Oh, and just if it aint been clear here is my car sat with my MK bones

andrews_45 - 17/12/06 at 12:14 AM

Please, can somebody please tell me do i need any castor. And if so, how much?

andrews_45 - 17/12/06 at 12:21 AM

Yes, you have a short memory. I did the same over a year ago when you helped me

http://www.locostbuilders.co.uk/viewthread.php?tid=29195

andrews_45 - 17/12/06 at 12:45 AM

quote:
Originally posted by snoopy
well appologies then if we met then why not believe me and why listen to other people who know nothing of mk and their products why are you now not as impressed as the day you came to us ?(or mk sportscars as i now have left)

Be fair charlie, I have only put this post to find out what I need to do now. I have in no way slagged MK off and since you wish to go through my previous posts you will be able to see that I have defended MK in the past when people have been asking 'why they do not answer the phone'

The be-all and end-all of this post is cause I am not sure who is right. At the end of the day, I am building a race car and it is important for me to get the handling right. I have ZERO experience of setting race cars up, but I have been told mine is wrong by several sources. You need to remember that before I put this post up I called MK and told them the problems I had, I was not convinced by their answer hence my original post.

Look, if people want to take it the wrong way and see it as MK baiting then you have too much time on your hands. I have no time for slagging folk off, as I have a race car to build in time for March.

As i keep stating all I want to know (as I am not convinced by my original reply) does my 750mc MK locost chassis need any castor? If it doesnt then there is no problem and we all go back to work. But if it does then I need to change the top wishbone

procomp - 17/12/06 at 11:16 AM

Hi right my last say on this.

1. we now know that he dose have the correct wishbones on the car and still has ZERO castor as MK said it should have.

2. All of the chassis from other manufacturers for the locost 750mc championship DO have castor on them.

3. The 750mc actualy state in the regs that the top brackets are allowed to be moved from the book dims to achive the desired castor . And currently all of the cars running in the championship are running LEGAL wishbones.

Charlie (snoopy) You say that i have been slaging Mk and martin kenan off in previous posts. But actually all i have done is to disscuss on a discusion forum what is actualy commonly known. IE that the INDY has lets just say not verry good rear geometry. This is accepted by martin as he offers a service to re jig the backend to correct the problems and HATS OFF to him for admitting and offering to do this.

Lets hope that MK sports cars offer the same deal with the top wishbones for thier locost kits. Unless they are going to openly say that ZERO castor is preferable to having castor.

Regarding my comments about the MK sprint when i and other didnt think the chassis was verry clever we were all told that the pics that we were looking at were of a prototype chassis and that the production version was going to be fully computrer designed to give better geo and more strenght in the chassis and since then i have made no further comments. Has the chassis beeen changed for production from the prototype one ?.

cheers matt

PS the 750mc already allowed the use of oval tubing in the locost championship as we were doing that since year 2000.

And the only wishbones that were bending were the luego ones whitch they strenghtend up and the MK ones which are still bending even the oval ones such as the ones fitted onto james oddonels car supplied earlier this year.

PPS paul aspden is no longer in buissnes setting cars up although he dose still do some grp work for kit cars.

[Edited on 17/12/06 by procomp]

[Edited on 17/12/06 by procomp]

Syd Bridge - 17/12/06 at 07:15 PM

I just found this thread.....incredible!

It's a very brave man who drives a car with NO caster. How does it self center? Shopping trolley geometry! You'd get big arms pretty quick!

And, the winning cars in the next 750mc Locost championship will probably be Procomp prepared, if not supplied. They will handle in a markedly different way to everything else, ....except mine!

So, if you want up-to-date handling and grip, go to Procomp, accept what Matt does and don't ask questions about specifics, because they won't be answered directly.

Cheers,
Syd.

DEAN C. - 17/12/06 at 09:36 PM

I think its about time I left this forum as I am getting more than a bit pi@@ed off with pratts slagging everyone off.

Some helpful forum this is,one person is after some help to correct a problem and idiots who should know better jump in slagging everyone off!

I for one will never deal with Procomp after the pathetic comments that have come out here again.
I thought he was a professional?
As for Aussie Sydney Bridge,who the hell opened his cage?Syd,everytime some crap starts flying you are somewhere near it,I wonder why??PS. I seem to remember the farce a year or so back about some accident damaged wishbones a certain nameless person used to con money with,you really do seem a nasty peice of work.

Thats it ,I'm off this forum..it's being spoilt by petty troublemakers,what a shame....

dilley - 17/12/06 at 09:44 PM

I couldnt agree more dean, it's a shame really, there are some really decent people on this forum and some very good information, I allways try and reply or post in an adult manner, some of the answers I have recieved have sounded like they have come from a bunch of primary school kids!!

andrews_45 - 17/12/06 at 09:51 PM

andrews_45 - 17/12/06 at 09:52 PM

I only wanted to know if I needed some in-built castor, and we end up at a complete tangent.

bob - 17/12/06 at 10:21 PM

funny really i kinda knew where this thread was going to head as soon as i saw it, couple of two footed tackles and we are off again.

my opinion on manufacturuers areas on this site for what its worth ........ they should read the posts in there area and answer the questions themselves,if they cant do that then they should ask chrisw to remove them from the site.

Mad Dave - 18/12/06 at 07:26 AM

I come on here less and less because of all the slagging off and bragging about how much more I know than you. Its pathetic

Syd Bridge - 18/12/06 at 09:20 AM

quote:
Originally posted by andrews_45
I only wanted to know if I needed some in-built castor, and we end up at a complete tangent.

Yes, you DO need castor.

About 7 degrees with Cortina uprights. That's what seems to be common in most of the intelligent world.

Sierra uprights can tolerate some more, depending on how heavy you can cope with your steering being.

Cheers,
Syd.

[Edited on 18/12/06 by Syd Bridge]

Syd Bridge - 18/12/06 at 09:27 AM

quote:
Originally posted by DEAN C.
I think its about time I left this forum as I am getting more than a bit pi@@ed off with pratts slagging everyone off.

Some helpful forum this is,one person is after some help to correct a problem and idiots who should know better jump in slagging everyone off!

I for one will never deal with Procomp after the pathetic comments that have come out here again.
I thought he was a professional?
As for Aussie Sydney Bridge,who the hell opened his cage?Syd,everytime some crap starts flying you are somewhere near it,I wonder why??PS. I seem to remember the farce a year or so back about some accident damaged wishbones a certain nameless person used to con money with,you really do seem a nasty peice of work.

Thats it ,I'm off this forum..it's being spoilt by petty troublemakers,what a shame....

No surprise you're an MK avid supporter. You've built one!

It appears that MK race wishbones are still in need of some attention, as are the originals which DO fail in racing without getting anywhere near an accident.

After that 'fiasco', some manufacturers actually strengthened up their designs, so it had some positive results.

When the kit industry here gets the same engineering oversight that is mandatory in Aus, a number of manufacturers will disappear, or be forced to make some fairly big changes to their products.

I don't want the Aus system, but unless the manufacturers design their products properly, then I see it as a necessity.

Cheers,
Syd.

andrews_45 - 18/12/06 at 07:07 PM

Well it looks like I might have to make some wishbones that will incorporate castor?

What about using valve springs to get the car to self centre? I have seen in old posts folk have done that, will that sort it out for me?

Finally thanks for some useful advice chaps

zxrlocost - 18/12/06 at 07:39 PM

hi mate

the valve springs is a trick to get your car to self centre

its not dangerous if done properly

it just shouldnt be needed

so I wouldnt Id do it the proper way

Hellfire - 18/12/06 at 08:58 PM

quote:
Originally posted by andrews_45
Well it looks like I might have to make some wishbones that will incorporate castor?

What about using valve springs to get the car to self centre? I have seen in old posts folk have done that, will that sort it out for me?

Finally thanks for some useful advice chaps

As Matt at Procomp is setting the car up for you, why not take some of his advice? No doubt he knows and has probably told you exactly what is required in order to get it to self centre and exactly how much castor is needed. If not, take it somewhere else to be set up or better still, get some advice from Syd Bridge and do it yourself

Phil

andrews_45 - 18/12/06 at 09:26 PM

Right chaps, MK himself has been in contact with me and he is keen to get the problem sorted.

Thanks for the help chaps

chrisg - 18/12/06 at 10:08 PM

I'm with DeanC and Mad Dave on this one I'm afraid.

It seems to me that certain posters have an adgenda with MK products, both MK sportscars and MK engineering and they're clutching at any sort of tenuous link to put the boot in.

I think manufacturers should stay out of this sort of discussion because whatever you post, well intentioned or not, looks like sour grapes.

If your advertising consists of bad mouthing the opposition then you're in for dissapointment.

I'd include ex manufacturers such as Keith (Syd) in this too.

Chris

andyps - 19/12/06 at 01:42 PM

quote:
Originally posted by andrews_45
Right chaps, MK himself has been in contact with me and he is keen to get the problem sorted.

Thanks for the help chaps

Let us know the technical outcome please.

andrews_45 - 19/12/06 at 08:02 PM

HMMMMMM, Deep breath.

Firstly I would like to thanks Martin Keenan and Baz for taking the time to contact me to discuss the situation. Martin sent me an email last night saying that he will put right any issues I have with my car FOC.

Martin said that when he designed the car it was designed to be run at 5-7 deg of castor. When the company was sold he sold all of the jigs to MK Sportscars and that is AFAHK what is still being used to make the wishbones. He has asked me to make clear in no uncertain terms, he has nothing to do with MK Sportscars

I also spoke to Baz at MK Sportscars and I spoke to the wrong person, who perhaps was not the best person to put technical problems to. He added that MK wishbones have 5-7 degs of positive castor built into them and assured me that my Locost will have the required castor incorporated into the design.

As you may have already guessed my car is at Procomp, who first pointed out the issue. Procomp are currently setting a MK car to race spec and have offered to do the required modifications to help me out.

At the minute, both MK and Procomp are saying differing things about the geometry, TBH this is the last of my worries as I just want to make the grid.

So can can we consider this matter closed

Carl

Hellfire - 22/12/06 at 02:21 PM

Absolutely amazing...

Grown men and manufacturers arguing about what is right or wrong. The results are shown on the track (racing setups/geometry) against road setup (comfort/handling). You cant have the best of both and all advice relative to such is subjective.

It's always the same old chestnuts that oik themselves out of the woodwork to have a stab, then oik themselves away again... there is little wonder this forum is spiralling downhill.

ATEOTD - you get what you pay for... if you want a racer - go to Caterham. Every other 7type Kit is an aspiring Caterham...

This is my first and last post in this thread... it's a joke!

Steve

[Edited on 22-12-06 by Hellfire]

andrews_45 - 22/12/06 at 06:58 PM

quote:
Originally posted by Hellfire
This is my first and last post in this thread... it's a joke!

Steve

[Edited on 22-12-06 by Hellfire]

First and last??? If only...

bob - 22/12/06 at 07:42 PM

quote:
Originally posted by andrews_45

quote:
Originally posted by Hellfire
This is my first and last post in this thread... it's a joke!

Steve

[Edited on 22-12-06 by Hellfire]

First and last??? If only...

If you really want to stop this "carry on" just delete your first original post of the thread and it will be gone.

andyps - 23/12/06 at 12:21 AM

quote:
Originally posted by andrews_45

quote:
Originally posted by Hellfire
This is my first and last post in this thread... it's a joke!

Steve

[Edited on 22-12-06 by Hellfire]

First and last??? If only...

Remeber that Hellfire has a split personality

Hellfire - 26/12/06 at 06:09 PM

quote:
Originally posted by andyps

quote:
Originally posted by andrews_45

quote:
Originally posted by Hellfire
This is my first and last post in this thread... it's a joke!

Steve

[Edited on 22-12-06 by Hellfire]

First and last??? If only...

Remeber that Hellfire has a split personality

We do indeed.... some people just don't see the author!

Steve

procomp - 27/12/06 at 06:56 PM

Hi just a quick q. Why have all the posts from SNOOPY (charlie) gone missing.

cheers matt

andrews_45 - 28/12/06 at 06:40 PM

quote:
Originally posted by procomp
Hi just a quick q. Why have all the posts from SNOOPY (charlie) gone missing.

cheers matt

Yes, just doesnt read the same with one LARGE spoon removed...

snoopy - 28/12/06 at 11:34 PM

[Edited on 28/12/06 by snoopy]