brynhamlet
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| posted on 20/9/08 at 02:00 AM |
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Spring rates
I apologies for asking something that has no doubt been asked before, but it’s keeping me awake
If I drop the bottom collar on the rear shockers, will it help to stop my car acting like a kangaroo on bumpy roads, or will I have to put softer
springs in.
Locost chassis, live rear axle, 1600OHV engine.
Front is fine, I’ve fiddled with the shock rates at rear, but it improves it, but not cures it. Fine on smoother roads.
I haven’t got a clue as to the existing spring rates, so can somebody suggest a starting point for new springs.
Car is normally driven solo and I’m about 13 stone in real money
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Paul TigerB6
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| posted on 20/9/08 at 02:11 AM |
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dropping the bottom collars will lower the ride height as well as slightly soften the rear end. Better bet might be to start off by backing off the
damper settings by turning them fully anti-clockwise.
Try a search for ride height for the Indy and go from there. It might be worth pulling the shocks off too - just incase someone has fitted a set of
front springs to the rear. I found a set of springs had the rating written on them which was hidden by the spring seat
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mr henderson
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| posted on 20/9/08 at 09:39 AM |
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Live axle 7's are very skittish due to the comparatively dire unsprung/sprung weight ratio.
There's a lot of useful info on this recent thread
http://www.locostbuilders.co.uk/viewthread.php?tid=96908
You will probably improve matters by fitting softer springs but this will be difficult to do unless you take the existing springs off and measure the
spring rate and the unfitted length.
John
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procomp
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| posted on 20/9/08 at 02:06 PM |
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Hi.
Quote "Live axle 7's are very skittish due to the comparatively dire unsprung/sprung weight ratio. " Is a complete load of
Bo###ks.
Basically for road use you will be wanting a rate of 140 - 160. This depend to some extent whether you are mainly using the car with driver only or
usually with two up. Most go with 150 as a compromise which means you may need to take it a bit easier when encountering long fast dipping roads when
two up. The race cars generally run as low as 100 - 140.
For length just measure you open length of the damper. jack the car up on the chassis at the back and then measure the bolt centers of the rear
dampers. Then you can work out what length spring will be needed. If it's a 13" open you will kneed a 9" spring. If it's a
12" open you will need an 8" spring.
HTH cheers Matt
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mr henderson
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| posted on 20/9/08 at 04:00 PM |
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quote:
Originally posted by procomp
Hi.
Quote "Live axle 7's are very skittish due to the comparatively dire unsprung/sprung weight ratio. " Is a complete load of
Bo###ks.
Oh no it isn't
"The unsprung weight of a wheel controls a trade-off between a wheel's bump-following ability and its vibration isolation. Bumps and
surface imperfections in the road cause tire compression--which induces a force on the unsprung weight. In time, the unsprung weight then responds to
this force with movement of its own. The amount of movement is inversely proportional to the weight - a lighter wheel which readily moves in response
to road bumps will have more grip when tracking over an imperfect road. For this reason, lighter wheels are often sought for high-performance
applications. In contrast, a heavier wheel which moves less will not absorb as much vibration; the irregularities of the road surface will transfer to
the cabin through the geometry of the suspension and hence ride quality is deteriorated."
http://en.wikipedia.org/wiki/Unsprung_weight
Let me know if there is anything else I can help with
John
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procomp
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| posted on 20/9/08 at 05:09 PM |
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Hi.
Mr henderson it is all very well quoting unsprung weight from Wikipedia. But you stated that seven type cars with a live axle are very skittish. Which
is simply not true. And what your second statement says has nothing to back up your first statement.
Any car with springs or dampers that are not matched to the aplication can make a car skittish. But to simply state that a seven with a live axle is
very skittish. Simply shows you have little idea of what you are talking about when it comes to driving or using or designing cars of this type in
real life situations.
And as for this comment " Let me know if there is anything else I can help with"
Well to be honest a lot of your posts show that you do not have much knowledge about these types of car at all really. So i certainly do not think
there is anything you can help me with. Except maybe spelling and grammar lessons.
Cheers Matt
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Syd Bridge
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| posted on 20/9/08 at 05:09 PM |
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A man just had to to know that the quote above came from Wikipedia.
Who wrote that total load of bollocks?
Moreso, what moron believed it?
There is no mention of the effect of shock absorbers(dampers), spring rate effect, and at what percentage of the total axle weight. that that
statement may even remotely come close to reality.
Mr.Henderson, you've told us a couple of times that you are not too good at maths and physics, so please try and do some research beyond that
cursed 'Wikipedia' before making such definitive statements.
Cheers,
Syd.
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Paul TigerB6
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| posted on 20/9/08 at 05:11 PM |
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Anyone want to join in on a group buy of popcorn??? 
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mad-butcher
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| posted on 20/9/08 at 05:17 PM |
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you could spray the entire car durring this one
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Syd Bridge
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| posted on 20/9/08 at 05:31 PM |
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Someone's gotta provide the entertainment and liven things up. 
Gee, I betta chek that my speeling is korekt, and the punchooayshun is rite az well.
Cheers,
Syd.
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mr henderson
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| posted on 20/9/08 at 05:32 PM |
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I think I will drop out of this one at this stage, now that Matt and Syd have decided to gang up. I have a history of arguments with both of these
gentlemen, and it nothing ever gets decided.
I do need to correct one thing, though, and that is that although my maths isn't too good (although I could probably meet the average here), my
grasp of physics is excellent.
So, if no-one else has anything to say then I wil say no more either. Readers can make their own minds up who to believe, or who they agree with
John
[Edited on 20/9/08 by mr henderson]
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irvined
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| posted on 20/9/08 at 05:39 PM |
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quote:
Originally posted by brynhamlet
I apologies for asking something that has no doubt been asked before, but it’s keeping me awake
If I drop the bottom collar on the rear shockers, will it help to stop my car acting like a kangaroo on bumpy roads, or will I have to put softer
springs in.
Before you fork out for new springs - check that your suspension travel is allowing for the amount of movement its trying to make.
I had to raise the back of my car an inch at SVA time to get the lights high enough. On the way back the suspension was reaching the end of its
travel and the car was fine on the smooth bits, but when hitting a bump in the bend, the car would jump a foot or so in whatever direction.
I'm a fat barsteward and my car is comparibly heavy (Lots of steel) so I'm running 160's on the rear - i'd probably go for
softer ones next time.
http://irvined.blogspot.com
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Custardtart
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| posted on 24/9/08 at 07:04 AM |
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quote:
Originally posted by brynhamlet
If I drop the bottom collar on the rear shockers, will it help to stop my car acting like a kangaroo on bumpy roads, or will I have to put softer
springs in.
Are you sure the rear shocks are ok, kangarooing is often used to describe the effect of knackered shocks?
The advice on spring rates sounds good to me provided the shocks are all working ok.
I do have to comment on the "skittish" quote though, if you believe this I strongly suggest you get your car set up by an expert or take
some driver training. Compared to a normal car the handling limits arrive with less warning but in real terms they can be made to "handle"
brilliantly and predictably and not at all "skittish".
They're only noodles
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mr henderson
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| posted on 24/9/08 at 08:39 PM |
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quote:
Originally posted by Syd Bridge
A man just had to to know that the quote above came from Wikipedia.
Who wrote that total load of bollocks?
Moreso, what moron believed it?
There is no mention of the effect of shock absorbers(dampers), spring rate effect, and at what percentage of the total axle weight. that that
statement may even remotely come close to reality.
Mr.Henderson, you've told us a couple of times that you are not too good at maths and physics, so please try and do some research beyond that
cursed 'Wikipedia' before making such definitive statements.
Cheers,
Syd.
Again, you nasty little piece of sh!t. Of course there is no mention of shock absorbers in that perfectly correct wikipedia article.
Why not, because it's an article about unsprung weight! Are you so intent on taking every opportunity to attack me that you let that little gem
of obvious truth slip pasts you! Why would there be any meniton of shock absorbers in a piece about unsprung weight?
If you want to learn about shock absorbers then look at the article on shock absorbers!.
You would be better off looking at the article on etiquette though, not that you would understand any of it.
Next time you want to call somebody a moron, I suggest you find an easier target.
Cheers
John
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mr henderson
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| posted on 24/9/08 at 08:46 PM |
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My apologies to anybody else having to read my riposte to Hissing Syd, but I'm not going to allow him to drive me off this forum in the way he
did to a well respected memebr previously.
He started with the personal attacks and each time he does it I will reply in a similar vein.
I would be perfectly happy to discuss the actual subject matter of the thread with him but I will not allow his personal remarks against me to go
unanswered
John
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Syd Bridge
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| posted on 24/9/08 at 08:55 PM |
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Oh dear dear dear..we're getting all hot and bothered aren't we.
And again, if you did your research properly, you'll find it was actually a Scotsman now residing in Cypress who did the damaging deed, and not
me!
All I ask to see on here is proper and infomed, sensible engineering. When I see something to the contrary, I will continue to raise its
unacceptibility to me, and other informed engineers.
Cheers,
Syd.
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Daddylonglegs
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| posted on 24/9/08 at 09:05 PM |
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Being fairly new to the site (as a regular user anyway), does this happen a lot?
[Edited on 24/9/08 by Daddylonglegs]
It looks like the Midget is winning at the moment......
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mr henderson
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| posted on 25/9/08 at 06:49 AM |
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quote:
Originally posted by Daddylonglegs
Being fairly new to the site (as a regular user anyway), does this happen a lot?
[Edited on 24/9/08 by Daddylonglegs]
No, it doesn't, and it won 't happen again as long as he refrains from making personal remarks about me, and keeps to the topic under
discussion.
You will note that, even though he has replied to my last post, he again hasn't added anything to the actual topic.
So, repetition for emphasis. If he stops making personal remarks, direct or implied, about me then Iwill say no more about him
John
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mr henderson
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| posted on 25/9/08 at 06:59 AM |
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quote:
Originally posted by Syd Bridge
All I ask to see on here is proper and infomed, sensible engineering. When I see something to the contrary, I will continue to raise its
unacceptibility to me, and other informed engineers.
Well, let's hear what you consider to be unacceptable in the article that I linked to, and better still, let's here your alternative
version (I'll bet we don't).
You see, it's all very well saying this is rubbish and that is rubbish, but it's about time you gave us your 'informed
engineer's' version.
Come on then, Syd. A challenge. Tells us all what is wrong with that article on unsprung weight. Please restrict yourself, as the writer of the
article had to do, to the topic of unsprung weight.
I'm waiting to hear your response.
Please note the lack of personal remarks in this post
John
[Edited on 25/9/08 by mr henderson]
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procomp
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| posted on 25/9/08 at 07:22 AM |
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Hi.
To be fair this sort of thing dose not happen very often. But of late there has been a lot of BS advice offered for no good reason.
If people start offering advice they should have at least some understanding of the topic in discussion . Rather than doing a bit of research on
Wikipedia and making statements that simply are not true.
The novice builder has enough trouble trying to get his head around many problems whilst learning about building a car. It is simply made even harder
when people start offering uninformed advice.
The above and other similar situations appear to be occurring when people who do not seem to be able to accept they are wrong about the statement
they wrote. It is a great shame realy as it would seem that certain people would rather let the novice builder who is asking for advice receive
uninformed advice rather than advice from people who have at least got something positive to offer to the discussion or from people who have vast
experience in the area that is being discussed.
Cheers Matt
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mr henderson
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| posted on 25/9/08 at 07:43 AM |
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quote:
Originally posted by procomp
Hi.
To be fair this sort of thing dose not happen very often. But of late there has been a lot of BS advice offered for no good reason.
But you personally are not able to say what is wrong with it, apparently.
quote:
Originally posted by procomp
If people start offering advice they should have at least some understanding of the topic in discussion . Rather than doing a bit of research on
Wikipedia and making statements that simply are not true.
But what in the statement that is untrue? If you are referring to my saying that the live axle cars are 'skittish', well,
'skittish' is a matter of opinion. Your opinion is obviously different to mine. I note that your main work is in the area of the racing
versions of these cars. AFAIK the cars you work with are not allowed independent rears?
If what I wrote is, to use your word, 'bollocks', I wonder why so many people that are free of restrictive race regulations, choose not to
use live axles? Any ideas about that? Could it be anything to do with the unsprung weight issue?
quote:
Originally posted by procomp
The novice builder has enough trouble trying to get his head around many problems whilst learning about building a car. It is simply made even harder
when people start offering uninformed advice.
The above and other similar situations appear to be occurring when people who do not seem to be able to accept they are wrong about the statement
they wrote. It is a great shame realy as it would seem that certain people would rather let the novice builder who is asking for advice receive
uninformed advice rather than advice from people who have at least got something positive to offer to the discussion or from people who have vast
experience in the area that is being discussed.
My advice is not uninformed at all, it is in fact very informed. I'm sorry that you don't think so but don't you think it would be
better if, instead of simply saying that I am talkng 'bollocks' that you actually said what it wrong with it?
As for me doing research on Wikipedia? ROFL!. I knew all about unsprung weight issues before Wikipedia and the internet itself were even thought of. I
knew about it when I was building and driving my live axle Dutton probably before you were born. I linked to the article so you could read
about unsprung weight from an independent and easily accessible source.
It remains a fact that the ratio of unsprung to sprung weight in any light car with a live axle is going to be undesirable, and you saying that that
is 'bollocks' isn't going to change that, and isn't going to change any of the other laws of physics either.
Perhaps if you hadn't started your first post on this thread in the way you did, we could have discussed this in a much calmer and more
productive way.
I look forward to your response, and trust that it will contain something more substantial than just saying that I am wrong, some actual proof (though
how you are going to disprove a basic law of physics I don't know).
Perhaps you would also bear in mind that many Locosts are driven on mostly public roads, which, as we all know, are not as smooth as your average race
track.
John
[Edited on 25/9/08 by mr henderson]
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procomp
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| posted on 25/9/08 at 08:31 AM |
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Hi.
If it's proof you need that a seven type car fitted with a live axle is not VERY SKITTISH. Then maybe you are the one wanting to do the
research. You could try by asking all those drivers who actually drive them on the road for starters. As i said earlier any car can be skittish if it
is fitted with dampers of the wrong valving or has springs not suited to the aplication.
The OP asked for a starting point for springs for road use. I gave him advice based on what myself and many many people have found to be rates that
offer a comfortable ride on the road and what people have found works on the race track.
Now i am sorry but your statement. Quote " Live axle 7's are very skittish due to the comparatively dire unsprung/sprung weight ratio.
" Is uninformed and completely untrue. IE Bo###ks. Are you there for saying that if i had not used the expression "Bo###ks" you
would retract your untrue statement. Or are you going to offer proof that your statement is correct. Or are you now going to give us your definition
of what very skittish means to yourself.
Now as for the unsprung weight being a problem on a live axle car. I have already said that if dampers and springs are used that have been selected to
suit the aplication then the unsprung weight issue is not such a problem.
As for skittish well the thing with the live axle is that it maintains the tyres footprint in a location that it was designed to be in. This actually
offers a stable footprint on the ground. It is however a completely different situation with just about all of the IRS designs that are around at the
moment with these type of cars. Most have very poor geometry control with toe and camber. It is actually these poor designs that actually have a
tendency to have a skittish behaviour. That is not to say that an irs can not be done properly just that most of the kit manufacturers have not
bothered to take the time to sort one properly.
And the reason most people buy/build kits with irs is purely that there are not many manufacturers offering kits with live axle these days. Due to the
fact that live axle units are not easy to find where as diff units are plenty full.
Cheers Matt
PS. I am now off to Snetterton for a weekends racing so will not reply until Monday. Although i would well imagine Fozzie will have also locked this
post also.
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mr henderson
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| posted on 25/9/08 at 08:49 AM |
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quote:
Originally posted by procomp
Hi.
If it's proof you need that a seven type car fitted with a live axle is not VERY SKITTISH. Then maybe you are the one wanting to do the
research. You could try by asking all those drivers who actually drive them on the road for starters.
Well, to be fair, I did say that the 'skittish' comment was an opinion. You seem to be treating it as some sort of quantifiable fact that
can be proved or disproved. It isn't, it's just an opinion, as indeed most adjectives that end in 'ish' are!
quote:
Originally posted by procomp
As i said earlier any car can be skittish if it is fitted with dampers of the wrong valving or has springs not suited to the aplication.
The OP asked for a starting point for springs for road use. I gave him advice based on what myself and many many people have found to be rates that
offer a comfortable ride on the road and what people have found works on the race track.
Yes indeed you did, I acknowledge that. Much better than Syd's non-contribution.
quote:
Originally posted by procomp
Now i am sorry but your statement. Quote " Live axle 7's are very skittish due to the comparatively dire unsprung/sprung weight ratio.
" Is uninformed and completely untrue. IE Bo###ks. Are you there for saying that if i had not used the expression "Bo###ks" you
would retract your untrue statement. Or are you going to offer proof that your statement is correct. Or are you now going to give us your definition
of what very skittish means to yourself.
Yes indeed I will, further down. I remind you, though, that skittishis an opinion, not an observable fact that can be proved or disproved.
quote:
Originally posted by procomp
Now as for the unsprung weight being a problem on a live axle car. I have already said that if dampers and springs are used that have been selected to
suit the aplication then the unsprung weight issue is not such a problem.
As for skittish well the thing with the live axle is that it maintains the tyres footprint in a location that it was designed to be in. This actually
offers a stable footprint on the ground. It is however a completely different situation with just about all of the IRS designs that are around at the
moment with these type of cars. Most have very poor geometry control with toe and camber. It is actually these poor designs that actually have a
tendency to have a skittish behaviour. That is not to say that an irs can not be done properly just that most of the kit manufacturers have not
bothered to take the time to sort one properly.
That's basically just contradiction, and the bit at the end about 'most kit manufacturers' is straying into territory that you and I
have had discussions about in the past.
quote:
Originally posted by procomp
And the reason most people buy/build kits with irs is purely that there are not many manufacturers offering kits with live axle these days. Due to the
fact that live axle units are not easy to find where as diff units are plenty full.
Basically a matter of opinion there, I reckon I could buy a live axle without too much trouble, and it would certainly be easier to design/build a
chassis using one than it would an IRS (the basic components of which are not exactly plentiful either)
quote:
Originally posted by procomp
Cheers Matt
PS. I am now off to Snetterton for a weekends racing so will not reply until Monday. Although i would well imagine Fozzie will have also locked this
post also.
I trust your team/customers will be sucessful and that the weather will be good.
I don't see any reason why Fozzie would want to lock this post as long as it continues in this calm and non-personal manner, and as long as the
'bollocks' type remarks are discontinued.
John
[Edited on 25/9/08 by mr henderson]
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mr henderson
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| posted on 25/9/08 at 09:37 AM |
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I’ve been taken up on my ‘very skittish’ remark earlier in this thread.
As I said before, ‘skittish’ is an opinion. It is not an observable fact. To be capable of being proved or disproved it would need to be tightly
defined with measurable parameters, and ‘ish’ at the end of an adjective is the very essence of vagueness.
This is a little bit from the wikipedia article, which puts it much better than I can (I added the bit in brackets for clarity) - The unsprung weight
of a wheel (and anything rigidly attached to it such as an axle) controls a trade-off between a wheel's bump-following ability and its vibration
isolation. Bumps and surface imperfections in the road cause tire compression--which induces a force on the unsprung weight. In time, the unsprung
weight then responds to this force with movement of its own. The amount of movement is inversely proportional to the weight - a lighter wheel which
readily moves in response to road bumps will have more grip when tracking over an imperfect road.
.
It may be that some of the respondents are thinking too much about smooth racetracks and not enough about average country road surfaces. They may also
be thinking about race situations where corners are taken at the maximum speed at which the vehicle can stay on the track, whereas on public roads we
have to drive at speeds which allow for an unseen obstruction around a curve, in other words, quite a bit slower! A car which has better grip on an
imperfect road will be, IMHO, less ‘skittish’ especially when negotiating curves.
John
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Syd Bridge
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| posted on 25/9/08 at 09:38 AM |
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quote:
Originally posted by mr henderson
I don't see any reason why Fozzie would want to lock this post as long as it continues in this calm and non-personal manner, and as long as the
'bollocks' type remarks are discontinued.
John
[Edited on 25/9/08 by mr henderson]
OK, Lets substitute 'bollocks' with 'uninformed anecdotal evidence'. Doesn't change the content or context much though.
And the worst 4 letter word I use is 'work'.
And I'll keep pointing out these instances of 'uninformed anecdotal evidence'.
As for long diatribes to substantiate my statements, they just won't happen. I've made this clear many times previously. As this all
overlaps with my work, I am not about to give away openly on the i'net, what I get paid for, regardless of how inconsequential or relevant it
may be.
If anyone happens to be in the same place as me and any other racers when these things are being discussed, then they will most certainly hear what I
will not put in writing, as well as the inputs of the others present.
Just as a forum member did at Silverstone. I think he went away that day, much the better off for the experience and discussions on racecar setup and
design he listened in on. A lot of it was not just Locost specific, either. And a thoroughly nice fella he is too. Even if he does speak with his
'ay oop' northern accent!
Cheers,
Syd.
]
[Edited on 25/9/08 by Syd Bridge]
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