RUMCars Forum

General Category => Additions to the Register => Topic started by: mharrell on June 25, 2010, 05:17:17 PM

Title: HMV Freeway
Post by: mharrell on June 25, 2010, 05:17:17 PM
Yesterday I traded my MGB for a yellow 1981 HMV Freeway so I suppose I should send the appropriate paperwork to the Register.

(http://farm2.static.flickr.com/1344/4732772437_7a270bdd9d.jpg)

Runs great; brakes need work.
Title: Re: HMV Freeway
Post by: marcus on June 25, 2010, 05:29:10 PM
Looks good in yellow, nice condition too.
Title: Re: HMV Freeway
Post by: Jean on June 25, 2010, 06:46:09 PM
Yes, please put on the Register it will be a first and an article to go with it for Tony Marshall would  be nice too.  Jean
Title: Re: HMV Freeway
Post by: Big Al on June 26, 2010, 10:38:34 AM
Saab, nice! Sorry where was the Freeway. Doh!
Title: Re: HMV Freeway
Post by: mharrell on June 28, 2010, 09:28:01 PM
Saab, nice! Sorry where was the Freeway. Doh!

The HMV is between the KV and the SAAB, just in front of the, um, other KV and other SAAB.  It's next to the MG....
Title: Re: HMV Freeway
Post by: Big Al on June 30, 2010, 10:03:40 AM
You realise in Britain the HMV would mean Her Majestie's Vehicle Freeway. Just right for a monarch and Corgi dog with enough room for wrist action waving. A whole new thing unless you want to be an old queen! I will shut up now.

Are there any Freeways in Europe?
Title: Re: HMV Freeway
Post by: marcus on June 30, 2010, 10:05:57 AM
NO, we have Motorways, Autobahnen, Autoroutes etc. Boom Boom, Ithangyou!
(I'll get me coat)
Title: Re: HMV Freeway
Post by: steven mandell on June 30, 2010, 01:40:20 PM
I've had one since 1992.  Never thought to register it until now.
All of them except for mine exhibit approx 1/4 inch of toe in per one inch of spring compression.  To be more exact- that figure is different for the right and left front wheels due to the off center location of the output ends of the ball and trunnion steering mechanism.  This necessitates unequal length steering controll arms that unfortunately also serve as the upper links to the suspension.  Therefore it is impossible with the original set up to get symmetrical changes in toe in (there shouldn't have been any in the first place), and camber with compression of the front suspension under usual driving conditions.

This also makes for a very exciting driving experience especially upon hitting bumps, and really dangerous if hitting a one wheel bump, or a diagonal elevation such as a railroad track or bridge break on a freeway at speed as the car will turn first one way and then quickly the other.  This rapid one -two, right - left punch seems like it wants to flip the car.  This is because whilst simultaneous imposition of significant two wheeled toe in can feel like it wants to trip the car as it becomes slightly asymmetrically pigeon toed- one wheeled toe in is the same as a steering input directing your vehicle's path towards the opposite side of the road.   

I could go on and on because as far as I know I am the only one who has ever figured out all the problem's of this car's suspension and steering.  I actually built a full scale working model of it off the car to figure out what was happening and why.  I also believe that I am the only one to ever engineer a proper solution to all the problems I discovered.

I engineered a mini rack and pinion unit with a centered output and 20 and a half inch long upper radius rods/steering arms to connect to an input point on the hubs behind (vs. ahead as on the original cars) of the front axle line. This had the effect of reducing toe in to 12 thousandths of an inch during one inch of spring compression - which is well within race car standards.  I also equalized and drastically increased the castor to approx 8 degrees for more self centering effect.  I also released the front springs from their highly compresed state for a smoother ride, as well as replaced all the rod ends and hardware store quality strap and ball pivot bushings with customized "alumibronze" bushings.  I also engineered the central transverse pivot rod that slips so sloppily within its 3 foot long grease filled tube that looks like a torsion bar ac cross the front end to be controlled by needle bearings.
The only thing original to the steering is the steering wheel, yet I am proud to be able to say that I managed to get the crazy suspension to actually work the way the designer had hoped for without sacrificing the weirdness of his design.  If you didn't peer around under the dash and front footwells you would never even see any of the modifications.

I also took out a tremendous source of lateral sway by creating custom made tunable bushings without the unneeded and unwanted lateral compliance of the originals.  Switching from the 3 stock 155 sr 12 inch tires to a rear mag wheel with a  Pirelli 175/50 x 13 " tire also helped as it has the stiffest sidewall available, and that is another major contributor to the destabilizing side sway that is endemic to three wheelers.  I put Yokohama 165/70 HR x 10" in the front to lower the center of gravity, allow for the increase the tire clearance required to ac comadate the greater castor angle causing the original tires to rub the inner fenders upon nearing full lock, and yes even slightly improve the aero- or in this case should I say arrow dynamics of the pointy nose beast.
Good luck on the brakes.  They are rather ineffectual.  At least they are conventional so not too hard to work on.
Don't forget to center your brake drums each time you take off the wheels by rotating the wheels slowly whilst tightening the lugs .   
Title: Re: HMV Freeway
Post by: Bob Purton on June 30, 2010, 06:36:07 PM
After reading all that the Messerschmitt doesnt sound so bad after all!
Title: Re: HMV Freeway
Post by: mharrell on June 30, 2010, 07:21:30 PM
Good luck on the brakes.

Thanks?  I'm certainly looking forward to putting a few miles on it now....
Title: Re: HMV Freeway
Post by: steven mandell on June 30, 2010, 08:12:38 PM
Better to be prepared for what you are likely to encounter than surprised by it.
Qiucker fixes that could have some of the effect of counter manding some of the more serious flaws include installing a pretty stiff steering stabilizer to nullify some of the the immediacy of the effect of the assymetrical bump steer, and running tire pressures of 18 psi front and 36 psi on the rear.   Lower pressure on the front will help you deal with the overly stiff springing on this end that was undoubetedly added to increase overall roll resistance of the vehicle.  The extra presure in the back tire will stiifen the sidewall and hence increase resistance to lateral sway where you have no other geometrical source of increasing roll resistance.  Try pushing laterally (cross wise) at the rear high point of the car and you will actually see the sidewalls bulge right then left as the car sways.  The same thing happens while you are driving.
Oh yeah, almost forgot- the rear swing arm is way too short and way too softly sprung, especialy when compared to the very stiff and quite often seized up front springing as the transverse rod on the 3 foot tube can get rusted in place.
Try pushing down on the front end, then the rear end to see what I'm talking about here.  The front end is unforgiving and the rear so soft and swing arm so short that you can actually see the effect of the wheel base  changing as the rear bobs eccessively up and down.  I had a girlfriend follow me on the freeway while I was in my Freeway before I spent a year and a half re engineering it.  She said it "hops up and down and a little side to side, just like a bunny".

Adjustable and stiffer rear shocks and springs from a motorcycle with a reduced overall length will bring the swing arm closer to a horizontal nuetral orientation when the vehicle is fully loaded.  This along with a change to the through bolt style of rubber isolators for the front rubber bushings that suspend both the engine and the swing arm, will go a long way towards eliminating the "bunny hop".

Or you could just look at it and stay below whatever speed rightly scares you and leave it at that.
I obviously felt inordinately compelled to make the Freeway able to be at least some what capble of being driven on the freeways without literally taking my life out of my own hands- hence my year and a half of creative diversion. 
Title: Re: HMV Freeway
Post by: marcus on June 30, 2010, 08:25:31 PM
Excellent stuff Steven, that's a lot to take in! With that knowledge and experience you could design and make your own new micro car/3 wheeler, so how about it?! ::)
Title: Re: HMV Freeway
Post by: steven mandell on June 30, 2010, 08:39:54 PM
Very insightfull of you.
About 15 years ago i was serious enough about it to design a futuristic and very aerodynamically efficient three wheeler in 1/12 scale after working out all the particulars of ergonomics and unitary chassis and drivetrain.
It eventually dawned on me that I don't work efficiently enough on such a large scale to be likely to pull this off alone- so I dropped it.
My AZ-1 has the right drivetrain, is plenty competent and thrilling to drive, but at 1500 lbs does weigh more than twice my target weight.
If I get rich quick and retire/ or get rid of a bout 25 cars it could be possible to continue in this vein.
Title: Re: HMV Freeway
Post by: marcus on June 30, 2010, 08:45:08 PM
Shame you cannot envisage taking on such a project, it sounds like you have the knowledge and skill to come up with something good! Then again, it's one thing to have the knowledge and skill to make something, and another thing entirely to make it economically viable as a product.
Title: Re: HMV Freeway
Post by: Big Al on July 01, 2010, 11:20:35 AM
NO, we have Motorways, Autobahnen, Autoroutes etc. Boom Boom, Ithangyou!
(I'll get me coat)

What about Urban Freeways, blue sign with a red steering wheel 'innit? Must have been a 70's design, wow man. Can you look urbane driving a Freeway? Can you sprawl and be urbane? Bad news for Freeway, they have been bought out by Paige of France.
Title: Re: HMV Freeway
Post by: mharrell on July 02, 2010, 12:44:22 AM
Better to be prepared for what you are likely to encounter than surprised by it.

You're quite right, of course, and in all seriousness I do appreciate the details you've provided.  I picked it up with an eye towards commuting on city streets, so I'll approach its limits with caution.
Title: Re: HMV Freeway
Post by: Big Al on July 02, 2010, 08:50:27 AM
On the comments of handling of the Freeway. How disappointing as it looks like a capable car. I could have happily owned one to drive where as most things American like King Midget do nothing for me really.
The handling sounds as compromised as the Tri Tech Schmitt. The reasons are different but related to a design disregarding the known ideals for camber, castor and akeman angles and progressive suspension. The only answer in both cases seems to be as radical as to remove some of the original parts. I do not know the history of Freeway but Tri Tech were copying a vehicle that handles pretty well with the parts coming available new to replicate the original suspension so there is little excuse for their poor design. It did for them in the end as the car in standard form is undrivable above about 45 mph. Several turned over on straight level roads resulting in police confiscationg one vehicle as evidence. I have had three rolled cars and a burned out one myself, broke two and two passed on plus I modded one bought from Andy Carter that is OK up to 55 mph but while I could get it even better I would begin to be concerned about the basic strength of the altered Tri Tech components.
Very frustrating to have a beautiful looking car, on paper with power to be usable but in reality as skitty as a bit of feather in a breeze.
For the Tri Tech it would now be possible to offer a new front suspension kit but fitting would be a major job requiring a front strip down and it would mean replacing the front crossmember to mount Schmitt suspension and a reworked front hydraulic braked hub assembly. Not cheap but the car would then perform up to the limit of the CN250 engine fitted. I cannot see this being successfull as you could buy a KR200 for the outlay unless you picked up the Tri Tech cheap. Indeed it would be cheaper to get the KR200 and put a CN250 in it. Better still now that most panels are available you can build a 'new' KR200 and put a CN250 in it.
My guess none of that is an option on the Freeway. Pity, nice little car.
Title: Re: HMV Freeway
Post by: marcus on July 02, 2010, 09:08:59 AM
I agree Alan, the Freeway does look better than many US micros/unusuals, shame it is flawed.
Title: Re: HMV Freeway
Post by: AndrewG on July 02, 2010, 01:04:52 PM
I find the Freeway a fascinating vehicle as it was very cleverly designed (by pukka automotive engineers, I believe) to be economical to produce in relatively small numbers.  This sort of real engineering ("an engineer builds for sixpence what any fool could make for half a crown") is a delight to me and is also useful for considering how a new microcar could be designed.  So I have been a lurker on Freeway forums for a long time.

It does seem that the designers got the front suspension geometry wrong - it may be that they thought it was a relatively slow vehicle and so they didn't need to be all that accurate.  Contrary to Stephen's description of the problem, most Freeway owners who have carried out a simple steering axis modification seem to be happy with the result.  This involves moving the bottom suspension pivot so that it is nearer the wheel centreline, dramatically reducing the positive steering offset - and we have to remember that in those pre-ABS days, all automotive engineers knew that the negative steering offset that is routinely used nowadays not only gave poor steering feel, but would be undriveable.

This is the original suspension and the steering axis (from the top of the McPherson-ish strut) can be seen to hit the ground completely inside the tyre:

(http://i86.photobucket.com/albums/k115/angibb/freeway68s.jpg)

Adding a bracket to relocate the bottom joint under the drum gives this:

(http://i86.photobucket.com/albums/k115/angibb/freeway83r.jpg)

And this is a good general view of the front end:

(http://i86.photobucket.com/albums/k115/angibb/freeway74s.jpg)

I should stress that not only do I not have any personal experience of Freeways, I've never even seen one 'in the flesh' - these are just repeats of other peoples' comments (and photos).

However I will add that Ackermann steering is often seen as ideal, but I don't think any designer would use pure Ackermann nowadays - it was Colin Chapman who actually used reverse Ackermann (inside wheel turns less angle than outside wheel) to compensate for the lower tyre slip angles on the more heavily-loaded outside wheel.

Andrew
Title: Re: HMV Freeway
Post by: steven mandell on July 03, 2010, 12:47:45 PM
Thank you for your contribution to offsetting (vs. correcting) one of the Freeway's many significant design flaws.
However if I am interpreting  your words correctly this modification towards negative offset steering axis should have the effects of reducing "steering feel", and increasing "undriveability".  So what other effect is being engendered that creates the perception/ possibly even the gestalt of a better steering vehicle?

I'm not saying that it couldn't happen.  With an original design as far off from geometrical ideals as the Freeway has- maybe two wrongs could seem to have the effect of make a more right.  But I am genuinely curious as to exactly what is going on to create this perception.

I also notice that this modification has had the unfortunate effect of raising the front end by what looks like to be at least a couple of inches.  I have modified mine to be a couple inches lower in the front instead by fitting 10 inch wheels instead of 12's in the front, as there was already too much ground clearance.  Lowering the c.g. on this  vehicle's only roll resisting "axle line" is obviously a good way to go to reduce the inherently greater risk of overturning that a 3 wheeled vehicle can present.  It also keeps the lower trailing arm much more parallel to the road surface thus allowing for far less effect of changing the instantaneous effective wheelbase while traversing bumps. With the more ideal design parameters that I have been able to achieve (without sacrificing the novelty of the designer's mesterpiece) and even with your suggested modification- keeping the trailing arm on the level should limit any further untoward influences on an already overly challenged set of geometries.  The shorter the effective trailing arm length (by way of not being in the wholly horizontal orientation)- the greater the change in incurred angularities while progressing through its working arc of travel.
It is also better from the point of aerodynamics in that it both reduces lift and drag by allowing less air under the car at speed, and even probably adds some down force as the front fenders now become more like downward pointing vs more upward pointing wings.  If one intends to drive the Freeway on the freeway at freeway speeds, this should become a significant consideration.
Title: Re: HMV Freeway
Post by: AndrewG on July 03, 2010, 03:13:40 PM
The owners who've done this small modification think it cures the Freeway handling issues - the Freeway Yahoo group http://autos.groups.yahoo.com/group/freewayhmv/ would be the place to ask them if this is correct.

Andrew