Suggestions for a book for off road buggy chassis design

[TMcRally]

Hi we are looking at entering off road racing and would like to build a small lightweight 2 seater buggy. < 1330cc / 750cc turbo.

Does anyone have a good recommendation for a book on chassis/suspension design.

Thanks
Dave

 

[GregLocock]

Carroll Smith's "... to Win" series covers the basics and costs the least and is highly regarded. You might try the FSAE buggy board as well.



Cheers

Greg Locock


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[TMcRally]

Thanks Greg

I ordered Engineer to win, I guess that's the one you meant and have signed up for FSAE - there is some reading to be done there, should keep me off the streets for a while.

Dave

 

[DanEE]

Ron Fournier's book below is one of the best in racing vehicle fabrication.. Excellent coverage of tube frame construction that should be very helpful.

http://www.amazon.com/reader/0895868709?_encoding=UTF8&ref_=sib_dp_pt#reader_0895868709

 

[patprimmer]

Off road is quite different to normal race car as handling bumps is much more important than handling curves, so books specific to off road may be required. I don't have anything better than an old very basic level book called how to build off road and dune buggies I think?

Off road suspension very much involves maximising travel and dampers.

Regards
Pat
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[Tmoose]

Ron Fournier has some interesting opinions. I believe in an old copy of that book he stated 4130 can not be brazed or bronze welded without severe weakening or brittleness. I think his explnation was based on Something about the bronze penetrating 4130's "grain." Overheating any steel part allows bronze to diffuse intergranularly with disastrous results.

http://reynoldstechnology.biz/assets/pdf/rtl_2010_moto_tech.pdf

There was a time when Reynolds 531 ( broadly similar properties to 4130) was joined routinely by bronze welding, but was tricky to TIG weld

 

[DanEE]

I have an older 1982 printing, 5th edition of the Fournier book..

His concern stated in this edition was the indiscrimate use of 4130 as he said "Unfortunately, chromemoly steel has become trick" in vogue or fashionable, apparently having observed people using it as he said "a little bit of knowledge is dangerous".

His concerns were multiple, particularly in roll cage construction, wanting a metal that will bend, rather than break.. with breaks being far more hazardous to the occupant. His comment "Under crash impact, a chrome moly steel part is much more likely to break rather than bend, as would a mild steel part".

I know in the off road, 4x4 market there have been some aftermarket chromemoly suspension parts fracturing due to improper or no stress relieving after welding.

 

[YvesLLewelyn]

Wouldn't good quality mild steel tubing be plenty good enough? - and a lot cheaper

 

[Tmoose]

1 - Buckling when axial load is exceeded - same
2 - permanent bending due to brief torsional or bending overload - 4130 wins ( 10% bigger diameter of lesser material buys LOTS more strength and stiffness, if that's what I want)
3 - fatigue failure due to repetitive loading - 4130 wins the brochure race, but tiny geometry details inadvertently done poorly will absolutely murder either material
4 - potential for local brittleness from too rapid cooling after welding, especially TIG or MIG - 41XX loses - potentially made FAR worse by the geometry similar to item 3

 

[GregLocock]

Offset that against robustness and post yield behaviour.

I'd favour cromo for the suspension arms, and build them big, and then something a bit better than the nastiest mild steel for the frame. This has been discussed several times, use the search engine.


Cheers

Greg Locock


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[harrisj]

Very often, stiffness of a suspension member is an important attribute as well as strength. Therefore a larger section of lower strength steel may perform better, be cheaper, easier to fabricate and more tolerant to damage and fatigue.

There's more to it than working out forces and cross-sectional area to determine stress and therefore material strength.

It's called design.

 

[patprimmer]

The problem with off road chassis is that any increase in weight to increase the strength of one part increases the load on other parts which then have to be reinforced to increase their strength which then adds weight and so on and so on.

Maximising strength where cracks or bending start while reducing weight where they don't is the key. Intelligent design and use of the correct material for each part is important.

Regular inspection and maintenance is also important, and reducing weight at the expense of durability is acceptable on non critical, non safety and easily replaced parts as by doing that we reduce the load on important suspension parts.

Regards
Pat
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[RSRCHSR]

Answering your question regarding books.. There are none directly related to off-road chassis building. Being personally in the off-road design industry I've dealt with many builders and all have their own opinions on suspension design, chassis wise most are similar in basic construction. majority using 4130 tube or DOM mild steel. 99% of all suspension pieces are 4130-N, with less than half of them actually stress relieving & normalizing after fabrication.