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Author: Subject: Concern over front suspension.
pinyachta

posted on 31/3/04 at 09:07 PM Reply With Quote
Spit bushes

The Spitfire bushes are pressed into the control arms with such interference they cannot rotate. The bolts generally set up in the sleeves and can't rotate either. Usually a torch is necessary to remove them. The bolts are 3/8" high strength steel torqued to maybe 25-30ftlbs..

The rear bushes on the Toyota trailing arms actually have teeth at the ends of the sleeve to eliminate any rotation.





Geo. Cushing, Delanson, NY

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jbmcsorley

posted on 31/3/04 at 09:36 PM Reply With Quote
revised front-end design

Hi Rorty,

To address one of your original comments... that the uprights are not coplanar...

I've worked out a revised front end design that results in the front uprights (LC/LD and FU1/2) being parallel and co-planer. This allows the upper wishbone brackets to be positioned anywhere along the outer face of the upright tubes.

I shared this revised design with a few builders that I've collaborated with in the past. Based on their feedback, it does greatly simplify the installation of the upper wishbone brackets. It also affords the opportunity to use standard stock-car racing parts (like upper cross-rails) right out of a catalog.

Here are some examples so you can see what I mean:

http://texaslocost.homestead.com/Suspension.html

http://www.geocities.com/isogriffination/

Perhaps this is more like what you had in mind, Rorty?

Does this redesign qualify me to publish my own book?

Cheers,
Jim McSorley


[Edited on 31/3/04 by jbmcsorley]

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britishtrident

posted on 31/3/04 at 09:38 PM Reply With Quote
I am sorry to be rude but I am going to come down heavy.
Bull sh*t -- no spacframe is ideal ie feeds all the loads into nodes, yes the detailing of the front and rear suspension brackets is less than ideal particularly the attachment points for the coil overs but thats life, the book chassis is more or less a carbon copy of a a pre-lit Westie so if you add up all the Westies and Locosts built that is a heck of lot cars some of them with truly daft oversized engines that work pretty well.

The metalastic bushes used were designed precisely for the jobs they are used for (they are actually wishbone pivots on Triumphs), Lotus used similar bushes with even less rubber on the Chapman era roads cars without problem. They were also used by many older cars and commercial vehicles as leaf spring eybushes I have never seen any bushes of this type cause problems or fail when used as they are in the Locost.

The book has serious faults but these ain't them.

[Edited on 31/3/04 by britishtrident]

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jbmcsorley

posted on 31/3/04 at 10:11 PM Reply With Quote
clarification

sorry about that britishtrident,

I didn't mean to pass judgement on the quality of the spaceframe... I was refering to the complexity of the front end by suggesting that it might not be 'ideal' for a DIY builder. This is based on my having talked to well over 50 other builders about this very subject.

If you take a look at the links I provided, as well as the results of my having studied the locost chassis for nearly 3 years (on my website), I think you'll find that my comments were intended to be constructive.

I'm quite familar with the faults in the book... it wasn't my intent to stir this already heated subject. sorry for that.

-Jim McSorley
Orland, FL, USA
http://mcsorley.net/locost

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derf

posted on 31/3/04 at 10:11 PM Reply With Quote
WOW this thing was dug up from the dead. I thought I read back far (about 6 months worth of posts, but this is from March of 03 a whole year.

As far as metalistic vs poly vs rubber bushings, metalistic is best, it will give the most firm and controlled car, rubber will be more compliant and it will allow the suspension to move (these are small so I'm sure the difference wont be that bad), and poly bushings are somewhere in the middle, I bought a few poly bushings the other day (supposed to be $128 worth, paid $20), and they came with metal sleves. As far as my understanding of bushings is that they dont rotate (not supposed to anyway), the steel inner tuber rotates around the bolt which passes through. I'm no expert, but every time Ive seen a suspension bushing that is how I thought it worked. When I do my suspension I fully expect to make the A arms, then make a jig like on page 2 or 3 and then I'm done. Yes the book is less than specific about this (waiting for 3rd edition) but that's why people like me look to others for inspiration and ask questions....

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JoelP

posted on 1/4/04 at 08:04 AM Reply With Quote
well derf, i dont think anyone will be bothered to argue anymore! people can just read the thread and decide what they believe.

But mine will be pinched tight

[Edited on 1/4/04 by JoelP]






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Peteff

posted on 1/4/04 at 08:48 AM Reply With Quote
Unless your brackets are very thick steel or you don't tighten your bolts you will find that the bracket will grip the crush tube and the polybush will rotate round it when the suspension is asembled.





yours, Pete

I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.

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James

posted on 1/4/04 at 09:52 AM Reply With Quote
quote:
Originally posted by JoelP

But mine will be pinched tight

[Edited on 1/4/04 by JoelP]


As will mine! Crush tube stays still, PU bush rotates around it.

James

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derf

posted on 1/4/04 at 01:04 PM Reply With Quote
was planning on leaving mine with a little bit of freeplay, just a hair. My crush tube doesnt fit into my brackets now, but I was gonna hit them on the grinding wheel for a few seconds each just to get them in snug.

I cant say that I read through the whole thing, but I did a lengthy skim of it, and found I really didnt care what was said. It is a small flaw in the design, but not one thats completely destructive. If a cars owner takes proper car of the car and once in a while they check to make sure that the bushings hasnt worn away (and replace as necessary) then you are fine. I take is as one of those intendid wear parts.

[Edited on 1/4/04 by derf]

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NS Dev

posted on 2/4/04 at 06:59 PM Reply With Quote
No, the rotation is completely provided by the twist of the rubber bushes! This system is used by nearly all road cars in existence so you can rest assured it works fine!! (though isn't that accurate!!)
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britishtrident

posted on 2/4/04 at 07:35 PM Reply With Quote
quote:
Originally posted by jollygreengiant
And for those of you not in the know, a METRIC bolt WILL have its grade of hardness/tensile strength marked on it as in 8.8, 10.2, 11.4, etc. This also makes it easy to spot the difference between an imperial nut/bolt and a metric nut/bolt.


Enjoy.


Nothing to do with metric or imperial ALL ht bolts are marked its requirement -- if it ain't marked it ain't ht

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JoelP

posted on 2/4/04 at 09:57 PM Reply With Quote
quote:
Originally posted by NS Dev
No, the rotation is completely provided by the twist of the rubber bushes! This system is used by nearly all road cars in existence so you can rest assured it works fine!! (though isn't that accurate!!)


im not sure, and i cant be arsed re-reading the thread, but i think it was poly bushes that are being discussed! but you're right about rubber bushes anyway






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Hodgson Super 7

posted on 6/12/04 at 03:20 AM Reply With Quote
Front end

I will like to show you the tools ,that I developed to do this part and you are completely rigth about it ,is better spent more time and doit well from the begining.
The most importand is the aligement tool that consist in a set of rods and bushings monted in the center line of the frame,so you can control the aligement betwin all the parts.
I shauld look for the pictures when we were builtding it ,and try to take new pictures tryng to explained how it works.

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