Author Topic: One of my deliveries  (Read 5298 times)

milnes

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Re: One of my deliveries
« Reply #15 on: March 08, 2014, 12:29:32 AM »
Steve you and I discussed the poor handling of the Freeway when I first said I wanted one. I'm not sure if I would be up to your engineering expertise but if you did write down in full how to resolve the problem I would really be interested.
I've also heard that someone manufactures a kit that can be fitted to the Freeway, which is suppose to resolve the handling issue, I'm just not sure how good it is though.

Jean I've sent you an E-mail on registering the cars.
I need to stop buying!

steven mandell

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Re: One of my deliveries
« Reply #16 on: March 08, 2014, 01:50:29 AM »
I really don't have time  for that right now
However I am willing to talk for probably about 30 minutes on your dime, and even supplement with an occasional picture of the features that are photographable, so that you can compile the modifications that it took me so long to work out into a usefull reference work to be shared with the microcar world.
Fair enough?  ;)

Jean

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Re: One of my deliveries
« Reply #17 on: March 08, 2014, 12:24:54 PM »
Jean I've sent you an E-mail on registering the cars.
[/quote]

Sorry Scott it must lost in the ether somewhere, when was it sent?  Jean
Jean
Register of Unusual Microcars

AndrewG

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Re: One of my deliveries
« Reply #18 on: March 09, 2014, 03:40:52 PM »
Here are two photos I have saved of an original Freeway front hub and one after the modification.

The steering axis runs through the centre of the top strut mount so on the original the steering axis hits the ground at about the inboard side of the tyre tread.  So any large fore and aft force on the wheel generates big steering reactions and kickback.

The modification moves the lower joint under the brake drum so that the steering axis hits the ground somewhere around the centre of the contact patch.  In modern chassis terminology that would be called zero scrub radius.  Modern cars have gone to negative scrub radius so that one wheel locking with ABS doesn't rip the steering wheel out of the driver's hands.

steven mandell

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Re: One of my deliveries
« Reply #19 on: March 09, 2014, 04:38:17 PM »
It appears that some one else has put their thinking caps on, and come up with an effective compensation, that ideally would mark the beginning of a more complete over haul of the front suspension and steering design and manufacturing inadequacies that also include:
1) Asymmetrical length steering rods that can never proscribe the same arc on the left and right front wheels during vertical wheel travel, ensuring different amounts of toe in/ out/ steering direction in right and left wheels when dealing with road irregularities, lean or varying weight loads.
2) The outboard ends of these steering arms connecting to arms welded to the top spring retaining piece, that given the overall design of this suspension, will never proscribe a continuous degree of arc, so both wheels are doomed to huge amounts of bump steer during vertical wheel travel, as the arcs prescribed by the out board ends of the steering arms can never match those of the steering arms.  So in addition to asymmetrical steering effect, changes in toe settings during vertical wheel travel are ensured, and stability of steering effect is further condemned.

3) Both steering arms are too short to allow for reasonably followable arcs being proscribed by their out board ends, albeit as mentioned above, one is considerably shorter (hence even worse than the other) due to the use of a ball and trunion steering unit, with its inherently offset inner steering arm pivot points, in a central single seat car.

The above is not even half of the design disasters built into just the front end, that my modifications sucessfully ameliorated, as opposed to compensated for.
« Last Edit: March 10, 2014, 05:45:48 AM by steven mandell »

AndrewG

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Re: One of my deliveries
« Reply #20 on: March 09, 2014, 07:00:09 PM »
Apart from its geometry failings, the Freeway's front suspension has always struck me as a masterpiece of efficient design (or 'design for production') for a microcar.  Things like using an anti-roll bar with trailing arms to make lower suspension arms is really clever - because it is so simple and uses so few parts.

My suspicion has always been that the designer was producing a 30mph vehicle and somewhere along the development line it doubled in speed.

steven mandell

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Re: One of my deliveries
« Reply #21 on: March 10, 2014, 07:06:41 AM »
Clever yes, but executed in only the most dire sense of the word.
The "anti roll bar" devolved from the inner pivot from which the single lower trailing arms swung.  It was a solid rod which fit quite loosely in a non machined tube that traversed the "front axle" of the vehicle, and was only isolated from the inner walls of this very long tube by filling the inter space with a tremendous amount of grease injected through a zerks fitting located midlength in said tube.   Needless to say this loosy goosey arrangement produced consistent inconsistencies in resulting front end suspension and steering geometries due to the lack of any machined bearings acting as a stable pivot point for the whole trailing arm assembly.
The front wheels were supposed to react independently, but when the atrocities of running this setup became obvious during use, it was decided that a lesser degree of danger would be encountered if the front wheels actions were better tied together, so that they would be less likely to want to wander in different directions.  To this end- the inner long pivot rod that was already welded to one lower trailing arm, got welded to the opposite one also.  This rod was way too thick to act as a successful anti roll bar.  In effect it really just defeated the independence of the front suspension for the sake of reducing the waywardness  of the front end's machinations.  The aforementioned hail Mary weld between the nut on the end of the axle rod and the trailing arm was overstressed to the point that these welds usually cracked- thus restoring to some degree the original frightful situation that they were called upon to help ablate.

OK, enough complaining already.  I said that I eventually fixed all the mission impossible problems, so here is my fix for this one:  I had an aluminum rod machined to be a near frictionless fit into the inside diameter of the aforementioned transverse rod/ axle tube.  I attached a grinding stone with it's flat surface perpendicular to the machined aluminum guide so as to provide a guarantee that when spun up in an electric drill and pressed up against the end of the tube, it allowed me to both slightly shorten and more importantly produce a machined flat surface suitable for the fitment of a bearing against it's surface.  Some diligent research produced surprisingly thin bearings up to the task.  One millimeter thin roller bearings sandwiched between hardened true washers now became interspersed between the tube ends and lower trailing arm pivots. 
This allowed for true independence of suspension, took out all the play at the highly leveraged against pivot point for the trailing arms, and even allowed me to choose the amount of tying together the actions of the front wheels/ anti roll effect to be selected by virtue of how much tension I choose to preload the bearing assembly with by how tightly I pulled on the bearing assembly via the now no longer welded nut at the end of the "front axle rod". 
Picture of 20 year old tube machining tool to follow.
« Last Edit: March 10, 2014, 07:14:13 AM by steven mandell »

steven mandell

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Re: One of my deliveries
« Reply #22 on: March 10, 2014, 07:53:07 AM »
Picture of drill chucked axle tube end machining tool that allowed subsequent fitment of needle roller bearings.


In reference to your guess that the HMV Freeway started out as a 30 mile an hour vehicle.
The designer builder made riding lawnmowers prior to creating this vehicle.
This gives more understanding as to the level of sophistication and tolerances that were allotted for the project.
Most of them came with Techumseh 16 hp garden tractor motors.
Naming it the HMV FREEWAY, of course gives away the fact that a 55 mph freeway use was the intent from the start.
However, after raising my gear ratio, and consequent top speed by virtue of a sprocket change-  I once found myself doing 64 mph- my highest ever speed, near the bottom of a long hill on one of Los Angeles' s freeways.  For a brief moment, I  rejoiced in my supposition that achieving this speed meant that it qualified as a real car. 
However,  this rejoicing was abruptly ended when I noticed a diagonal break in the highway pavement that represented a sizeable bump fast approaching.  Based on previous encounters with diagonally orientated bumps, I was seriously concerned about my chances of surviving this encounter.  I held on tight to the steering wheel, ducked, closed my eyes and braced for the worst.  Bang!. bang!  I was gratefully astonished to realize that although I was now in a different lane, the vehicle was still pointing forward, and had not rolled!

I drove it more slowly home, put it up on jackstands, and spent the next year and a half in my journey of discovery and inventive corrections.  In the interim, they raised the freeway speed limits in the States back to 65 mph.  This meant that going much less than the now average 70 mph freeway speeds in addition to all the swerving around of other vehicles at this speed to get a better look, made the return of the corrected HMV Freeway to the freeways of Los Angeles an unwise choice.   
To wit,. I am still breathing.
« Last Edit: March 11, 2014, 10:57:49 AM by steven mandell »

Big Al

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Re: One of my deliveries
« Reply #23 on: March 10, 2014, 08:35:47 AM »
An interesting situation. It shows that the basics of getting the front of the car to work reliably is not just a case of slide-rules and engineers. You can clearly see that the turning center point is in the wrong place. If you get a suitable pencil and washer to fit on the end you can recreate the original version and the modified. Not convinced, model a whole axle. So constructors of home grown cars take note.

As to the suspension to steering relation ship, that is more difficult as there a lot of variables. However eliminating built in handling probs, as above, will make the layout easier to get right. Microcars do offer challenges, not least of limited space, weight and often small wheels which tend to magnify problems. As the guys have demonstrated, the design can be a product of anticipated performance, and thus certain cars have adequate set up for their design, without it being as good as it could be. The alternative way of looking at this is the good designs can cope with greater demands and tuning up those cars is thus more possible. In all cases a limit will be reached where safety is compromised by the design. This dovetails into our brief imaginary best micros or racing micros threads.

The Tri Tech has several of the problems that are exhibited by the Freeway. The solution could be along similar lines, however there is an off the shelf answer that can be fitted in this case. That is the remanufactured original Schmitt set up armed with uprated brakes, of which there are several well documented routes. That Tri Tech chose not to do this themselves is in no doubt a reason the Schmitt was not as successful as it should have been. Need of a return on investment by production and over confidence in an undoubtedly crafty modification of a cheap component to use as the heart of their front suspension probably being the reasons, I expect. A near miss as with good underpinning there is no reason a Tri Tech would not cruise a 70 mph and offer some spirited B road driving with a 250cc scooter engine offering an excess of power. In its standard form 45 mph is a challenge to control.

With the Freeway steering it sounds like the gear needs to supply its leverage input to an idler which is positioned to equal out the steering inputs for each side.
« Last Edit: March 10, 2014, 08:49:16 AM by Big Al »
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Bob Purton

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Re: One of my deliveries
« Reply #24 on: March 10, 2014, 09:32:58 AM »
Well done Steven. Just the stuff I like to read.

AndrewG

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Re: One of my deliveries
« Reply #25 on: March 10, 2014, 02:49:20 PM »
One huge difference between the 1950s microcars and the 1970s(?) Freeway was the production volumes they were designed for.  The Freeway appears to be built only from steel tube or items that appear in an engineering supply house catalogue, whereas the 1950s microcars have plenty of custom castings or machined parts.  The Freeway is much more like a kitcar - another similarity to the Tri-Tech.

steven mandell

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Re: One of my deliveries
« Reply #26 on: March 10, 2014, 03:37:27 PM »
Andrew,
Please do us all a big favor by taking a picture from inside the vehicle that shows the steering box and attached control rods, as well as the steering arms welded to the top spring retaining caps, so that our viewers can visualize this highly unique, albeit problem ridden arrangement..
As payment, the microcar world will be enabled to see an elegant solution that I have created that does away with most of the other "unsolvable compromises" imposed by this architecture.
Bob and Al at least will really appreciate this one. :)