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MG Midget and Sprite Technical - Spridget front suspension redesign

Anyone seen this before?

http://drc.libraries.uc.edu/bitstream/handle/2374.UC/744092/MET2015_Eastham_Cooper.pdf?sequence=1

Rob
MG Moneypit

Seems like a guy with a lot of time on his hands.

It looks over complicated and doesn't appear to solve the problem of the damping effect not being in line with the suspension movement. ie, it's still in the same place as the Frontline setup.

That "L" bracket looks particularly scary.

Although the Frontline setup is not perfect it is better than the orginal and you can just buy it and bolt it on.
The only advantage I can see with this, is the adjustability of it, but how much negative camber do you want?
Bernie Higginson

That is scary, I'm not sure what is worse the apparent lack of understanding of the function of the upper link with a single rose joint at the inner end or that a supervisor allowed that to go ahead. I just hope he doesn't design anything near me. Overall I would say it leaves a lot of room for improvement. Likely something is going to fail big time and the wheel fall off when the brakes are applied hard.
David Billington

Wow!
G Lazarus

End result has its design faults which his supervisor should really have picked him up on early in the project.

But I would certainly give him credit for the amount of work in calculations and draughting, and good for thinking "outside the box" in the positioning of the tube shock. That is quite novel and clever. What I think was missing was sufficient initial understanding of the main problems with the standard arrangement so perhaps he just didn't do enough preparatory research.
Guy W

The other thing that surprised me is that although there is quite a lot of work involved in it, the scope seems far too narrow and limited for a Masters qualification. Maybe engineering degrees are different but in my experience that would be far more applicable to an undergraduate thesis than a Masters degree.
Guy W

Where does it say anything about a masters degree, all I can see is it being partial for the requirements of a BSc so a normal engineering degree.
David Billington

I don't know! I don't know where that came from, I must have just mis-read the title then! :-)
Probably about right for a BSc thesis then (equivalent to 10% of marks?)
Guy W

It reminds me a bit like the front suspension of the Rover P6 but in that case the suspension link to damper was a ball joint where the top of the king pin would be on a midget. Also the Rover P6 had a massive bulkhead to take the suspension spring which was braced against it. The Midget of course doesn't have much of a bulkhead so that would be out of the question.

http://www.uniquecarsandparts.com.au/images/how_to_repair/Suspension/Suspension_Large_2.jpg

Rob
MG Moneypit

Rob,

As I understand it that Rover was an early example of a car designed for safety with a strong passenger cell and crushable front and rear hence the suspension design with the spring being against the structural bulkhead.
David Billington

" I would certainly give him credit for the amount of work in calculations"

<<When simulating the motion of the upper control arm in Solidworks, it was discovered that every vertical inch of wheel travel translated to about an eighth of an inch of shock travel. So, for five inches of wheel travel, the shock would only compress about one inch.>>

Go figure!


He could also have done with proofreading before submitting his thesis.
Dave O'Neill 2

Yes, there are lots of spelling and grammatical errors. I blame reliance on spellcheckers which don't pick up on the wrong word used, but spelled correctly! But then, he aspires to be an Engineer, so what would one expect! ;-)
Guy W

Hm. Overly complex I suspect. Not sure how or if it would work in real life, you'd need a very odd damper.

The P6 is a totally different beast when it comes to front suspension. Horizontal springs and a massively strong bulkhead, coupled with a substantial arm arrangement and dampers that work backwards (bump extends the damper). It was originally designed to make a big as possible space to fit a gas turbine engine in.

It's got some very odd characteristics, enormous camber change over suspension travel being one of them.

Also, a personal grump, but the damper damps and the springs absorb shocks. But that's just me.
Rob Armstrong

Maybe they are metric inches.

Just flicked through, intetesting project. But yes, some scary errors and designs. Rod ends in bending! Argh! However, As a fairly recent (less than ten years ago) graduate I sympathise to some extent. I doubt I could have done much better. University sadly teaches you nothing about real engineering! Only once you get into industry do you really start learning how to do things properly.

Cheers
Malc.

Malcolm Le Chevalier

Page 19 - Total vehicle weight of 1590lb which is 721Kg which I suspect most road cars (except the Frogeye) will exceed by anything from 50 to 100+Kg. The vehicle weight calculations should also include passengers.

I guess he also missed a reference book out, just saying.

He should have had a chat with Tom Colby of Speedwell.

He should have had a chat with Peter May.

I think he might find the Spridget Mania kit is the Frontline kit or a copy.

He was unaware of all the alternative kits available as well as Peter's top link.

A really good solution would be to produce an adaption of the Frontline kit with alternative (shorter) top arms to tailor the negative camber side to side (differences in manufacture of the original cars) and ride heights, as well produce a lighter version. Or a really good solution would be a means of producing a bracket and hybrid top arm for the Armstrong unit that also reduced weight and created a means to adjust camber (or various neg camber top sections).

I didn't read that the kit requires bodywork modifications for it to fit.

I guess when he says 'gas shocks' he means telescopic dampers.

Heim is brand name, as far as I can recall.

Modern shocks to allow adjustability - I guess he didn't talk to Peter C long enough.

I think I'll stop now.

Daniel Stapleton

Malcolm,

What rod end in bending? The only rod end I can see is fitted to the inner end of the original damper arm and so is hardly in bending as it can't provide any support to the top end of the kingpin other than due to the rigidity of the upper trunnion bolt. I suspect in any real use the L bracket bearing arrangement would wear out in short order due to the load and poor support.
David Billington

... obviously, like many, he didn't posses a relevant copy of the Driver's Handbook (for his weight figures at least).

A photo of the Rover set up (for interest?) -


Nigel Atkins

I thought I saw some in some of the pictures David, but I did just flick through. Will have a proper read when I get infront of a computer.
Malcolm Le Chevalier

Malcolm,

When I first looked at the components picture I assumed the rod end on the damper arm was for the outer end at the top trunnion but was staggered when I saw a later pic which showed it attached to the body pick-up. The other 2 rod ends are those on the drop link to the lower wishbone and so pin joint effectively.
David Billington

without being too mean, cos we all have to start somewhere, but the supervisor should have picked up on a few things. One Glaring issue is that apparently adjustability is more than twice as important as safety, which is twice as important as having the same 'wheel path'

Dunno about anyone else, but those are in the wrong order for me. Safety f(a)irst, then making sure it does the same thing, then make it adjustable if you can.

He's also made the classic mistake of coming in under budget without appearing to include labour charges for making the strange lever mechanism

The Solidworks picture is different from the final design, quite a bit different. Makes you wonder why a design was done?
Rob Armstrong

Looks like a uni project or something to me. I like a bit of thinking outside the box and doing something new. Unsure about how long that clamo/bearing will last on that arm, but I guess that will be revealed (maybe) with time.



I really like the idea of having a linkage to mount the shocks horizontally across the engine bay. But there would be too much butchering and stuff for what I can be ar*ed to do.
Karl Bielby

I wonder if they ever experimented with a Hydrolastic system on a Spridget. Probably not considered "sporty" enough for what was expected of a sports car of the day, though set up correctly it gave good roadholding performance.
Guy W

If you weigh it all up, he hasn't really improved the original setup. He still has a single top link without any triangulation. The initial damping effort is behind the line of suspension travel, so it will still twist under braking and cornering. But my main gripe is that awful L bracket. Why is there only one bush in the "bushing block"? Surely two would have supported it better. I suppose the ultimate question is "Would I have it on my car?" NO! Not even if it was free.
b higginson

The point that a number of people on here seem to miss is that this is a piece of academic work and not a real engineering project. The purpose of such an academic project (an undergradute thesis) is to demonstrate to your examiners that you understand how to go about a design to build process and how to apply your engineering knowledge along the way. I graduated in a scientific discipline and not an engineering one, but I'd guess that this is probably a very typical piece of work that is produced by many thousands of students every year with no intention of ever producing anything other than a one-off prototype.
Simon Wood

Having written a bsc thesis, I completely understand from where this academic piece is coming from. However, it still needs to be correct. There is a final proof of design aspect and it just says yep, it works, but I didn't really test it.

It's more that the supervisor and reviewers should really have picked up on fairly major mis-considerations. That's the bit that concerns me, in that unless the reader is on the ball, this is seen as an OK way to do things.

Well done to the chap for getting a decent idea for the project though.
Rob Armstrong

Omg....whag the freak man

I cant begin to make heads or tails of that insanity

I do like the coil over shock and ive thought about that from time to time but with out the hymn rose joints...but my thought was to make the top wishbone on a sliding platform to adjust the ,chamber...i do disagree with him i think it could fit with a little ingenuity

But wow what an imagination to come up with that idea he had


Ill have to look him up later today....and see what became of him


Im kind of surprised this is for a masters degree it looks more inline with a doctrate dissertation

Prop
1 Paper

lol Prop. This is for a Bachelors degree. A doctorate Thesis is a much more beefy piece of work, with a Masters thesis in between.

Here's a doctorate thesis.

http://etheses.whiterose.ac.uk/3832/1/00_Measurement_of_Shielding_in_Electrically_Large_Metallic_Enclosures.pdf

Rob Armstrong

That is true rob ...maybe its the ocean that makes them differant...haha

Ido enjoy reading doctrate thieaes on line from the university of missouri. Just up the road....they are interwsting some good and some ...just scary

Haha
1 Paper

A lot of work for just a damper conversion. We built this set up a year ago and its in test this year, both road and track. Offers adjustability in all dimensions. This version is compatible with out hubs and discs only, a set up for original parts will follow on later this year or next.


J L HEAP

I like that coil over shock set up

Good grief rob your dissertation was well beyound my comperhion skills... i hope that paid off inthe real world...cha ching

Haha



1 Paper

Bernie,

A single top link still but with the structural connection to the lever arm spindle removed and replaced by a rod end so removing the upper links ability to resist the forces applied to it during braking, that's no upgrade IMO that's a downgrade.

Simon,

It may be an academic exercise, although he did produce a working version, but as an engineer myself he shows a shocking lack of understanding of the forces at work and how to deal with them.

A comment was made earlier in the thread about the calculations done, I would say they were minimal at best as he didn't even work out the loads for the upper and lower links due to braking. I did those back when I designed my upper link assembly and it showed the braking torque forces were additive to the lower wishbone and subtractive to the upper link hence the disparity in their sizes and why the single upper link worked well in the original design as the loading is fairly low in comparison to the lower wishbone.
David Billington

Yep. Can't argue with the above. I've never done any force calculations though. I am working my way through a degree level suspension book but it's slow going.

Prop, my car insurance is 30quid cheaper. Totally worth it.
Rob Armstrong

"... obviously, like many, he didn't posses a relevant copy of the Driver's Handbook"

Nigel, that made me laugh out loud, good to have you back!

Jeremy T2

For a piece of acadamic work it's not very well written at all. It looks a lot like I have an idea and will select/undertake bare minimum research and then do it anyway. I don't think it even considered polymer/rubber rod end bearings for road use.
Daniel Stapleton

At least he is having ago and not dealing drugs :-)

I remember my bachelors thesis was full of mistakes. Like most students, I was more interested in going to the pub and pursuing girls instead of working. My thesis was cobbled together the (all) night before it was due.

I thought my technical writing was good until I want into industry. The first design report I wrote was returned to me covered in red pen, with a post it on the front saying "you may as well start again". It's a learning process. He will learn and go on to be a better engineer.

How long did it take you to write your book that shall not be named Daniel?

Cheers,
Malc.
Malcolm Le Chevalier

Malc. He might have done his suspension re-design while he was ON drugs😂.

Seriously though, I wonder why he didn't carry out some road tests. Surely, the proof of the pudding is in the eating.

David.Yes, I agree it is a downgrade. He mentions that the single top link is angled to cope with torque generated during acceleration and braking. Torque at the front wheels during acceleration is negligible to be almost non existent.

b higginson

It may not be brilliant, but a) he is interested in Spridgets and b) committed enough to choose this as his thesis topic and at least give it a good try. I just hope he doesn't visit here and get discouraged in his interest in Spridget ownership with all the negative comments!

As a final submission it could have/ should have been better but that suggests to me that he had insufficient mentoring or guidance from his tutor. If the kit is now fitted on his car I hope the deficiencies and hazards become obvious to him, or are pointed out to him, before anything fails catastrophically.
Guy W

"insufficient mentoring or guidance from his tutor"

is exactly the issue here I think. Good effort for trying, and double points for getting MG content into a BSc dissertation!

I know there's a fine line between student doing it and supervisor doing it, but there has to be a bit of a steer surely so that big errors don't make it through?

I sense a lack of time as it nears completion (as with ALL projects with an unmovable deadline!) but it's an OK start.
Rob Armstrong

Jeremy,
;) .
Nigel Atkins

This thread was discussed between 08/01/2017 and 10/01/2017

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