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Tube Frame or VW Pan

B Bgeo91316
In an email Bill Steele sent to me dirctly he asked about the differences between Speedsters with tube frame and a pan based frame. It's good question but I am not qualified to answer it.

I thought some other contributors, through far more experience, might be able to shed light differences.

To kick of the discussion I'll offer my reply to Bill Steel's question.

Bill,

"I first test drove a pan based built car for a few minutes in 1971. Henry Reisner's father's company Automobili Intermechanica built that car in Santa Ana. It was at an auto dealership, in Pasadena, CA which had an arrangement to sell them. I also have driven a Vintage Speedster in about (2001) for a few minutes nearby by their facility. In about 2001, I've sat in Dale Bate's Intermechanica at Knott's and both of John Leader's JPS's, also. My daily driver is a 67 VW with a stock engine.

I met Tom McBurnie about four years ago at Knott's and he was displaying his frame, which at the time was licensed to Street Beast's, but apparently their arrangement fell apart last year. So when I approached him early in 2004 he was willing to do my build.

Pan based replicas feel nothing like VW's. But a big part of the difference may be that they always have freshly rebuilt engines which are usually more powerful than the VW's I've driven. Also, the seat height, the angle of your legs to the pedals, and your height above the road create a much different "feel". My desire for a tube frame was motivated more by interior space considerations and a desire to be centered on the steering wheel when sitting in the car. It's my understanding that pan based cars put the driver a little (about 3") to the right of the steering wheel's center. Not a big deal perhaps but I would think somewhat fatiguing on long drives. And the VW pan is narrower than the speedster body, so certain there are certain "space loosing" design concessions when mating the Speedster body to the VW pan.

Having said all this, I would not even try to compare the road handling of the pan based Speedster to the a tube frame Speedster. Test driving these cars briefly on surface streets is not a true measure of their real prowess (in my opinion). After taking delivery of my car (last Friday) I drove about 120 freeway miles from El Cajon to the San Fernando Valley, it was fun and I was impressed with the power of my 1915 cc engine and smoothness of the ride. Then two days later I took about a half hour drive on an old road through a local canyon loop that is a favorite of sports car owners and motorcyclists. As careful and controlled as I was (because of the cars newness and my lack of familiarity with its capabilities) this ride will be an enduring memory for me. I think you need to find someone on the SOC site who has owned both and driven them under different conditions to get a fair idea of the differences. (I think Alan Merklin probably has more experience in this area than almost anybody.) Having said that, I think there are small differences between each build that make comparison very difficult."





1957 Thunder Ranch(Speedster)
Original Post

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B Bgeo91316
In an email Bill Steele sent to me dirctly he asked about the differences between Speedsters with tube frame and a pan based frame. It's good question but I am not qualified to answer it.

I thought some other contributors, through far more experience, might be able to shed light differences.

To kick of the discussion I'll offer my reply to Bill Steel's question.

Bill,

"I first test drove a pan based built car for a few minutes in 1971. Henry Reisner's father's company Automobili Intermechanica built that car in Santa Ana. It was at an auto dealership, in Pasadena, CA which had an arrangement to sell them. I also have driven a Vintage Speedster in about (2001) for a few minutes nearby by their facility. In about 2001, I've sat in Dale Bate's Intermechanica at Knott's and both of John Leader's JPS's, also. My daily driver is a 67 VW with a stock engine.

I met Tom McBurnie about four years ago at Knott's and he was displaying his frame, which at the time was licensed to Street Beast's, but apparently their arrangement fell apart last year. So when I approached him early in 2004 he was willing to do my build.

Pan based replicas feel nothing like VW's. But a big part of the difference may be that they always have freshly rebuilt engines which are usually more powerful than the VW's I've driven. Also, the seat height, the angle of your legs to the pedals, and your height above the road create a much different "feel". My desire for a tube frame was motivated more by interior space considerations and a desire to be centered on the steering wheel when sitting in the car. It's my understanding that pan based cars put the driver a little (about 3") to the right of the steering wheel's center. Not a big deal perhaps but I would think somewhat fatiguing on long drives. And the VW pan is narrower than the speedster body, so certain there are certain "space loosing" design concessions when mating the Speedster body to the VW pan.

Having said all this, I would not even try to compare the road handling of the pan based Speedster to the a tube frame Speedster. Test driving these cars briefly on surface streets is not a true measure of their real prowess (in my opinion). After taking delivery of my car (last Friday) I drove about 120 freeway miles from El Cajon to the San Fernando Valley, it was fun and I was impressed with the power of my 1915 cc engine and smoothness of the ride. Then two days later I took about a half hour drive on an old road through a local canyon loop that is a favorite of sports car owners and motorcyclists. As careful and controlled as I was (because of the cars newness and my lack of familiarity with its capabilities) this ride will be an enduring memory for me. I think you need to find someone on the SOC site who has owned both and driven them under different conditions to get a fair idea of the differences. (I think Alan Merklin probably has more experience in this area than almost anybody.) Having said that, I think there are small differences between each build that make comparison very difficult."





Alan MerklinAlan MerklinDrclock - Elkins, West Virginia Supporting Member
Thanks Bill for the kudos however I only have limited experience with a tube frame speedster.
The one and only tube frame I have driven was a Intermeccanica, overall the doors, deck and trunk lids felt very solid as well as a nimble driver similar to a production vehicle. The tube frame is easier on driver comfort as there is a wider driver's floor'footwell area and a lower center tunnel.
A pan/chassis based speedster has the "road/seat of the pants feel while driving, the driver's left footwell rest position a bit tight. They also tend to flex ever so slightly but this is easily resolved with minor chassis / pan improvements.
A couple of years ago I built a outlaw speedster with a Raby T-IV engine and trans combo, four wheel disc's, gas shocks 3/4" sway bars and other chassis improvements, it handled well on winding roads. Driving along one day I saw what was to me a vehicle test facility aka a new parking lot, at 70 plus going from 4th to 2nd 4th into a full controlled slide, running the rpm's back up into third and recovered without dropping below 45 mph, it was completely stable and felt fully in control... For the money, a pan chassis, if done correctly can be easily set up to handle well.
FM Former Member
My two cents: tube frames handle better, are safer structurally in the event of a crash, and in the instance of IM's allow better weight distribution (engine/transaxle moved almost 3" forward).

Go take a look at the decades old, clapped-out, rusty pans most builders "reclaim" and chop for building their pan based replicas... not a very inspiring sight.
B Bgeo91316
Alan's pan looks pretty nice to me and the prepped pans I've seen at JPS and Vintage seem to be from the high end of what's available then restored to primo condition.

The safety advantage of a tube frame seems a little specious to me, too. It's like, "would you rather be hit by a semi while driving a Sportster or a Fat Boy? Gimme a choice.

I think the weight distribution is a very important factor. A rear engined car with unequal weight distribution can turn into a centrifuge ride, particularly in wet or icy conditions.

FM Former Member
Just for the record: When we say "pan based", we should clarify that many manufacturers (JPS for example) include a very stout metal subframe (2 x 4 and 2 x 2 steel tubing) which is mounted directly onto the pan. This makes for a very rigid chassis. Someone new to this forum might think we are only talking about a bare, unreinforced pan. I guess some older pan based cars do not have this reinforcement, but I for one sure wouldn't want one. JPS chassis are very sturdy, which allows for a softer suspensiion and hence a more comfortable ride while maintaining good vehicle handling.

In my case, I opted for 3/4 inch anti-say bars front and rear, and padded tranny straps to help control the fatter rubber that goes with a flared car. As far as interior space goes, I added a dead pedal to counteract the driver's lateral G-forces, aligned the pedals to allow heel-toe downshifts and moved the steering 1.5 inches left to better see the instruments. It all seems to work. What is it Jake always says, "You have to look at it as a system". Well the same holds true for the chassis. It all depends on how you intend to use it. Cruz'n or bruz'n?
JogyverJogyver
Suggestion.... Used these cars as fun toys and not roadracers. The torsional stiffness of all ladder or twin frame designs of which all these Replica Speedters are made up of are very poor. Ask any Speedster manufacturer what there opinion is on hard road driving. Yes you can play around with different shock rebounds, different coil spring rates, different sway bar thicknesses your are still creating risk. Oh I forgot your cross weight, front to rear weight and the CG. Have you ever broke traction in a turn and tried to corrected it? Do you know how it feels when in that turn the sidewall of the tire rolls under and then bites? Next you know you are on your lid. Hopefully you are straped in the seat with a 5 point safety harness, wearing helmet, and have a full cage over your head.It's not the design of the frame... it's how you use your head when you drive this car. Then again if you are a racer you do take risks. We walk way from a roll over crash.

Do you want to eliminate some twist ( think Unibody) .... weld the pan to Speedster frame. It sure beat silicone rubber, sheet metal screws and lag bolts.
Later
Joe
D D-man
Somewhere else on this site is a thread on roll bars. If one were to weld a healthy roll bar directly to the inner frame with a short 45 degree brace, it seems to me that should offer some protection in a roll over? Especially if the inner frame was welded to the pan. Nothing will protect you if you drive like "Wide Rides" at Mach II, but it would seen to offer some protection. D-man
JogyverJogyver
Darryl, You would need to place a cross or X type bar configiration to keep the back portion of the roll bar from twisting down. Kind of like a cork screw.
Below is an example of getting bite on a side wall. I rolled 6 times Two in the fence and four on the asphalt. The car was too tight . The only thing bruised that day was my pride. I lead most of the race with 10 laps to go. That's racin.
zumwollzumwoll
I first decided I wanted a 356 at the Campout at Gary's Obsolete in McMinnville, near Portland, last June. Gary and his familiy race 356s themselves and care for cars at the races. They recommended that if you can afford it , by the tube frame by IM-- "it's the only way to go". SO I bought a used IM car with some obvious problems (engine trans etc) and more problems that surfaced after I started getting into resolving those problems.
SO now I have substantially more money into this rig than I woulld have spent for a new JPS or any of the other pan based units and its still not right.
So if I had to it all over again, I might have gone for a an out of the factory car or---heaven forbid buy an original coupe for even less money.
But maybe in a few months I will feel differently. Now If i had $30k just itching to be spent then I would opt for a frame. Just makes sense to me.
I had a 240S Datsun that had been porfessionally modified in Calif and that car never handled right regardless of sway bars and bracing. A complete roll cage woul have been different but getting in and out would be tough and interior room would be minim,al.
I hope I have adequately confused you.
Last tought, I have never in my forty years of messing with cars met a more helpful guy than Henry. I belive you never actually own his cars. They are forever his---as in the proud papa and you are just taking care of it and enjoying it. If yoiu have a problem with an IM, it is Henry's problem.
FM Former Member
Ralph, your statement about Henry rings true. Meeting him last Spring comfirmed my decision to buy an IM Speedster. But what really sold me was driving Dale Bate's beautiful black 58 IM. The car is so much more stable, solid feeling, detailed, and handled so much better than my VS it was like night and day.

This is not some elitist statement. Pan based cars are the heart and soul of this hobby/passion for Speedster Replicas and I loved my VS. Heck I drove it over 5600 miles in 2004 alone, including an LA trip from OKC and back. I hated to give it up... but for an IM I did.

Back to framed IMs. Besides the solid platform, there is really something to that engine inched forward. I could feel it the very first time I cranked the car around a turn with speed.

The other thing that appeals to me is that Henry's layout allows for a more accurate appearing replication of a Speedster and it allows the buyer to get into those details on a diffrent level. The options on suspension, braking, engines, and etc are much more varied and doable. And the bottom line? The IMs are truly built at a level that takes them to a true handcrafted sports car status.

But, heck, all of these are fun cars. The homebuilts have a special place in my heart, and I loved my VS and saw the quality in the JPS build too. I am anxious to check out Bill Georges stunning T-Ranch Speedster and Ray's silver bullet from Beck.
FM Former Member
Mr. Soltis: having owned and competed with an original '56 Speedster, and driven some VS and JPS pan based cars, I can say without quivocation that the IM tube-framed cars are far superior in handling. Anyone who has ever competed in an original Porsche Speedster or a VW (yes, people did race VW bugs) knows that under hard cornering the doors may fly open due to extreme chassis flex.

Oh, and it's a good idea not to open the door when one of these original cars is jacked up.
Alan MerklinAlan MerklinDrclock - Elkins, West Virginia Supporting Member
Other than the very nice IM you have, I have no idea as to the "why" of making these less than accurate statements.
A Type 1 Beetle in good condition as well as a properly shortened and refurbished Speedster pan/chassis can certainly be jacked up under the pan w/o a door related problem.
Realizing that the original chassis/pan and Beetle body made up a durable and strong combination.
A refurbished chassis/pan assembly that is mated to the stout 2x4 steel box frame work and glassed into the speedster body greatly increases the strength of the chasis/pan configuration.
I do this for winter storage by centering a floor jack under the pan jacking the speedster so all four wheels are clear of the floor, then rotate the car 90 degrees and rolling the jack with the car balanced on it, up against the rear shop wall to obtain additional work space.
Works for me over the past twenty five or so years.

"Clapped out pans" and now "doors flying open"......

"Captain we are breaking up!"
FM Former Member
I agree that a tube frame is superior to a pan under conditions where you are pushing the car hard. Although many of us wish to believe we drive these cars hard, the fact is that they are babied, and the vast majority of speedster owners rarely if ever push their cars to the point that the tube frame would make any significant difference.
JogyverJogyver
Mr. Brown: Thanks for sharing your kitcar experiences with us all. I do have some agreement you regarding the IM chassis. The characteristics of the IM chassis are similar in design with the other kit pan speedsters with the exception of the front frame/ axle design. Most kit Speedsters have a frame incorporated into the body. Yours obviously does not. The body is set over the frame. The basic concept for the speedster is that the frame configurations are a twin rail design. Yes the CMC, JPS and others do have a frame. If it is installed properly it will have the same structural integrity. The Speedster manufacturers have design theses car to make them affordable yet being able to make some profit. If you want a properly designed race style tube chassis it will more than triple the kitcar cost. Your street ride comfort will be gone. In regards to handling one could setup any unibody car (no frame) to run circles around your car. With different spring rates, shocks, weight displacement, and suspension mods any of these kit cars will handle great. You will still have the frame torsion. As I stated before , ask your manufacturer how much they support the concept of hard driving or racing one of their cars. The point to get across to most everyone is use your head not your foot.
I enjoy this site because of the great people sharing ideas. Everyone Speedsters whether all out classic, plain and simple or all out wild are awesome. Do I think my car is better than yours or anyone else. The answer is no. I do take pride in my work. If anyone has questions I am always will to help any way I can.
Lets start a new topic......Whats better .....round tube or square tube?

FM Former Member
On the point of structural rigidity I have to agree with some about the Pan Based cars. My (just sold) VS was just as solid 3 years/2months and 28,000 miles down the road as it was on the day of delivery in August 2001. The door/trunk/engine lid fit was still excellent and the paint always received high points from lookers/car buffs. For the $$, Kirk built me a great car. I buffed her out the evening before it went to Justin (a member of this forum) and sat in the shop for an hour or so staring at it, noting all the reasons I liked it in the first place. Heck, my wife was teary eyed over seeing it leave our garage. That Speedster R was reliable as it could be and provided hours of fun.

On the other hand, I will say it again. The handling, solid feel, detail, quality of the mold, fitment, correct appearance, quality of materials, availability of nearly any option you would wish for, and the excellent road manners of the IM I drove were at a level that took it a step above any other Speedster R I have driven or right seated. It is an incredible custom built replica. But, that comes at a cost. I won't abuse the obvious cliche' here. I will say though that by the time I replaced the mexi-crate in the VS, and did a host of mods like gearing/gas tank/seats/caps/CSP Exhaust/etc., well, it was at the base $$ of the IM in cost.
I took those lessons in getting it 'right' into this IM.

I too see the beauty in the variations on the dream... flared, home built, classic, GTs, etc. Some of the track racer looking cars at the Eastern meet are my favorite appearing Speedster Rs. Gordon's CMC comes to mind, the classic beauty of Fern, and GBs mega build all fit in the line-up. I love the Subesters too. On the west side there is John Leader's example of what can be done with a pan (Ghia) based Speedy GT, Brian Bell's great looking CMC, Paul's scream machine, Dale's great road tripper, and Scott's absolute definition of an IM custom outlaw. I love them all.

Jim
FM Former Member
All:

Thanks for contributing to my knowledge base on these cars.

When I asked Bill about Pan vs. Tube frame cars, I was really after his impressions personally. I do think anyone who had driven both types is qualified to render an opinion on their impressions.

I also understand that only a few that contribute on this site possess either the training and/or depth of practical experience needed to pass judgment on the relative merits of one versus the other approach to the design and construction of these cars (you know who you are), the rest of us as just amateurs passing stories around the camp fire.

Of the regular participants on these threads, I think most of us have identified those we really should listen to when something important is at stake and who needs to be taken with a grain of salt. The good news is, even around the campfire, once in a great while you learn something.

Bill
FM Former Member
Joe,

I have a fraction of experience and knowledge compared to many on this forum. I have no real race experience, other than grudge racing 1/4s as a younger man. My only TRUE drivers training was a basic 2 day course sponsored by the PCA at Hallet Reaceway. Soooo... my opinions have very little basis in anything other than what I feel from the seat of the pants and in comparison of my VS and an IM.

Jim
FM Former Member
Bill:

I think your observations are exactly the point GB was making. His point was pan based cars (including the 356) are not as stiff as most purpose built tube frame cars.

Anyone doubting GB assertion about the open door incident should pick up a copy of Dr. Thiriar's book. It's also a superb book on Speedster's in general.

Bill

B Bgeo91316
Bill Steele: My point in the post immediately above was to add independent verification of what George Brown had posted above, not to dispute anything he said. I believe Dr. Thereirs' comments substantiate the weaknesses of pan based frames, even if they are Porsche designed and mounted under real 356's.

Also, at the recent Knott's show I ran accross a fellow who was displaying a new Speedster tube frame. He was back near the Manx display area. He's been building cars for quite awhile, and at the request of some of his clients he's designed a new rectangular boxed steel tube frame. I didn't have a chance to discuss how adaptable it is to the fiberglass bodies that are designed for VW pans, but I would imagine he would discuss the retro-fit with anybody who is interested.

His name is David Barrett, email address is jadbarrett@msn.com Telephone number is (559) 876-3217 location Fresno, CA

This frame looked very much like the one JPS /John Steele had on display, although I didn't get a close look at John Steele's frame (because he recently warned me about blabbing about all his propriety parts and procedures, etc. So I've decided to avoid Mr. Steele [and his manufacturing secrets] as much as possible).
B Bgeo91316
I'd love to hear Jim(Bob)Ward's comments and comparisons.

After the drive from B.C. to Knott's then back to O.K. in his new Intermecanica, he's got a few miles racked-up in both pan based and tube frame based Speedster Replicas now. And in spite of the differences in some of the other characteristics (like weight distribution) maybe he's got a clear view of how the pan or frame effected the handling of his two Speedsters.
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