When I drive my new speedster from Vintage Motor Cars, when shifting up the 3rd the traction is great. When driving in 4rd at 90km/hour ~ 55miles/hours it feels likes that is the max safe speed. Over that speed the car is a bit shaking to the left and right. Is that all normal? Or what are you findings around that?
a beginner with just 800km ~ 500 miles on the car.
Carlos
Replies sorted oldest to newest
forgot the add the engine info: 2332cc Aircooled Engine Specs
No, that's not normal. My Speedster felt fine up to 80+ mph (130 kph), which was as fast as I wanted to go in it.
I don't believe 'safe' and 'Speedster Replica' belong in the same sentence
Have you had a good shop do a 4 wheel alignment? I’d start there with Danny’s Camber/Caster/Toe In numbers. Also, you may want to play around with tire pressures.
Funny Story: (not really) When I bought my Spyder and drove it home from Chicagoland to NYC, it wandered all over the road. I didn’t do much with it for a few years, then I dropped it off at SE to have some upgrades done.
It wasn’t until I got the car back and swapped out the 165-15’s for 205/60-15 and 195/65-15’s that I realized that the two 4.5” wheels were on one side and the two 5.5’s were on the other.
When I got them properly F/R it handled a LOT better. 
And I still have the new ball joints I was going to put on because I thought they must be shot sitting on a shelf.
I have the tire pressure test to the advice setting. The car has only 800km ~ 500 miles on it. I ask our mechanic for a 4 wheel alignment. The mechanic noticed that that one of the axle's started to leak, they are fixing that soon, could that have impact on it?
For sure I will ask for a 4 wheel alignment when it goes in for the axle repair.
@Lane Anderson posted:No, that's not normal. My Speedster felt fine up to 80+ mph (130 kph), which was as fast as I wanted to go in it.
My Spyder gets pretty light about 85. When I get finished with the mods I have in mind I’m sure it will be fine to ~100.
But I rarely drive it more than 60, tbh.
When I first bought my speedster, I used to travel at a maximum of 65mph on the highways, as that was my comfort level. The more I drove, the more I got comfortable. I'm guessing you will as well.
I recently put 165/15's on my car, switching out the 185/15's. It appears the larger diameter tire (they are slightly over 1" taller) allows the car to travel at higher speeds and lower rpm's. The new tires are also much more comfortable, but I have traded off cornering ability with the swap. The steering seems much lighter, as the new tires are 1.25" narrower. Regardless of the tires I had on my car, I've never experienced any shaking or vibrations.
With all that said, I'm comfortable traveling at speeds of 80+mph in the car. Someone once asked me if I felt safe doing 70mph. I told them the way I look at it, I'm dead if I crash at anything over 55mph. (I see these cars as motorcycles with larger fairings)
Your speed is a determination of your comfort level. Perhaps it's not responsible to go a high rate of speed in these cars (or any older car) as safety wasn't really factored in during the construction of older cars. Some may say the larger older cars (chevys, lincolns, cadillacs, etc) are safe due to their size. But I've seen crash test videos that suggest otherwise.
hi Kevin, thanks for sharing this viewpoint and your info! You put everything in the true perspective.
All that is very valid. But you would be amazed at the difference 1/8” of toe in or of 1° of caster can make. Make sure your suspension/steering is 100% correct before you start accepting handling characteristics that aren’t confidence inspiring.
just my 2¢.
OK, @Carlos P, Here's my 2 cents worth.
I have a full IRS (non-swing arm) car with 205/16" wheels all around.
All four wheels are original Fuchs (not reproductions) from a 911 (now all 6" wide) and the tires are Michelin something or other running tire pressures of 22 front, 26 rear (yes, they are a tad stiff - I could probably drop a pound or two).
I have had all four wheels/tires "Road Force Balanced" to perfectly dial them in. It took me almost 20 years to discover this service and get it done and I wonder each time I take her out why it took me so long - It's that good.
I have had a 4-wheel alignment done (1970 VW sedan specs) where the front end caster was set to 6º . THAT was very important because before that, she wandered, chasing the crest of the lane and any bumps she found. That made the front end seem squirrely and it wandered a lot, especially with cross-winds. After a proper alignment and getting the caster between 5º - 7º, she became very stable above 60mph and stays that way all the way up to 100 or so (on the track, of course 
). It is sometimes still a bit subject to cross winds, but it's a pretty light car so I can live with that and it's minor, to be sure.
I have run a combination of tires of 205/16 front and up to 225 rear (I have a wide body car) and after a proper alignment and caster adjustment I see no highway difference between the larger tires and going down to 205s - It seems to handle similarly on highways with either, but the 225's on the rear REALLY made a positive difference cornering hard on the track.
So, to summarize; I feel safe and secure at any reasonable highway speed up to and beyond 85-ish, including riding in the turbulent wake behind a tractor-trailer, given setting my 4-wheel alignment to the 1970 VW sedan specs but adding caster to get to the 5º - 7º range. THAT made all the difference.
Full pan IRS MG TD with MWS wire wheels and 165/80-15s exhibits a little cowl shake at 50-60 mph but smooths out after that and feels fine at 85.
Spyder with Vintage 190s and 165/80-15s in summer compound also has a slight vibration at 55 mph but smooths out at 60 or so and feels fine to at least um... 150 kph
You need more caster than people generally put in their cars. You need something more than a bubble balance on your tires. You need every piece of steering linkage to be "as new" and tightened.
I feel completely fine up to 95. It gets skippy at a buck-ten (not that I'd *ahem* know). At around 100 mph, it's aerodynamics working against you as much as suspension - going faster means setting up the car to be lower. This sets other issues in motion (front caster, and rear camber on an IRS car), but they can be overcome.
If you only feel safe to 55, there's a problem. The car says "speedster" right there on the fenders. It's gotta go faster than a bicycle.
.
Stan, Gordon, and others are right about all the suspension and alignment bits that need to be set up right.
But if the car is jumping around at 55, the very first thing I'd check is tire pressure, especially up front. I once had a tire shop set the pressure to 32 psi, because that's sort of normal for sort of normal cars.
But our cars are very light in the front and need substantially lower pressure if you're going to have any grip at all. If they're not already there, set the fronts to 22 psi at most and see if that makes a significant difference.
.
the tire pressures is set to Front 26 / Back 30, based on the recommendation of Vintage Motor Cars. I will do a test by lowering it to 22.
Yeah, and with all due respect to your Vintage guys, 26/30 is WAY too hard. As Mitch mentions, 22 front/26 rear MAX and probably a bit less than that.
On the track, where I would be cornering hard, I was at 24/28 and dropped back down to 20/24 on the street. That seemed about right.
Oh, and BTW, my CMC has been 4-corner weighed at exactly 2,000 pounds so she's a tad pudgy.
@Carlos P posted:When I drive my new speedster from Vintage Motor Cars, when shifting up the 3rd the traction is great. When driving in 4rd at 90km/hour ~ 55miles/hours it feels likes that is the max safe speed. Over that speed the car is a bit shaking to the left and right. Is that all normal? Or what are you findings around that?
a beginner with just 800km ~ 500 miles on the car.
Carlos
Carlos,
All of what you need to know is in the archives.
Tire pressure: 22 front, 26 rear. Weight in the front; spare tire & tools or add weight. I have 26 pounds added, no spare. 5-6 degrees of caster (add 2 shims to the front beam). Front sway bar. Rear camber compensator.
Your big engine is worthless if you can't drive the car.
I have a '72 pan. The Bentley manual says a '72 Beetle with radial tires should have 18 psi front and 27 psi rear for 165R15 tires.
Since my Speedster weighs about the same I use 18 psi front and 28 psi rear.
I have been wondering what effect, if any, tire width has on pressure to be used.
Tire width isn't as responsive to pressure as the size of the sidewalls. That's why a 55 or 60 series (tall and skinny) rides a bit softer than a 40 series (short sidewalls).
I run 175/70 instead of the Beetle 185/80.
Speaking of speed (in any of my cars), as I have gotten older I sometimes find myself driving under the speed limit. It is kind of disturbing.
@Gordon Nichols posted:Tire width isn't as responsive to pressure as the size of the sidewalls. That's why a 55 or 60 series (tall and skinny) rides a bit softer than a 40 series (short sidewalls).
Come on, dude, a 55 aspect ratio tire is not "tall and skinny." This is especially so when fit to a chassis designed for an 80-series tire. A 165/80-15 (FKA 590-15, AKA F78-15) is tall and skinny. A 205/60-15, not so much.
If you check the load rating on tires of those respective sizes you'll develop an idea for what sorts of (comically, frighteningly, blasphemously low) PSI are appropriate for use on our plastic clown cars. Your 205mm wide tire is putting down significantly more rubber (i.e. square inches) and therefore will require concomitantly fewer pounds per square inch to support the weight of our mighty conveyances with an amusingly tooth-jarring ride.
Just to get some contrast data, I looked up some factory tire pressure specs. I'm truly trying to get a grasp on what they might tell us about setting pressures on speedsters/spyders.
2020 Honda Gold Wing (motorcycle)
Curb weight: 800 lbs
Engine: flat 6 cylinder 1833cc - 125hp - mid-engined 
Front tire: 130/70R-18 - pressure 36 PSI
Rear tire: 200/55-16 - pressure 41 PSI
-----------------------------------------------------------------------------
2017 Smart ForTwo (car?)
Curb weight: 2050 lbs
Engine: turbo 1000cc - 89hp - Located in rear
Front tire: 165/65-16 - pressure 29 PSI
Rear tire: 185/60-16 - pressure 36 PSI
Load rating, shmode rating.....If I run my front 205/50’s down below 20 pounds of air, they respond with all sorts of distressed animal-sounding noises while cornering, which doesn’t happen when I pump them up. Thus far, I haven’t lost any teeth at my current pressures (surprisingly so, for a auld phart with lots of crowns covering up past indiscretions) and still consider that my original premise still holds. However, a lower pressure will also tend to make the tread curl or ripple given sideways pressure from cornering (as much as an over-powered VW Beetle in wolf’s clothing can induce) and that rippling will cause portions of the tread to lose road contact.
At least that’s what I remember from an ancient, SCCA autocross driver ed class I took in the ‘60’s. But that was when radial tires had just become popular and the class instructor didn’t believe that they would give better course times.
.
@edsnova posted:....Come on, dude, a 55 aspect ratio tire is not "tall and skinny."...
Wasn't it Charles Goodyear who said you can never be too tall or too skinny?
Thinking about tires certainly has changed over the years.
.
.
I think car manufacturer tire pressure recommendations used to be based upon a mix of performance and comfortable ride back in the old days, but now they're based strictly on maxing out fuel economy.
.
This chart MAY help you:
https://www.tiresplus.com/tire...re-load-index-chart/
An example would be the tires on my Cayman. Rear are 265/40R18. Load range is 101.
That means the tire will support 1819 pounds at 50 psi max pressure.
Cold pressure is 37 pounds, which is 74% of 50 pounds(or 1346 pounds).
Fronts are 235/40R18 Load range 91at 50 psi. Cold pressure is 30 psi, or 60%(813 pounds).
Doing the math: 813 on each front tire and 1346 max on each rear, so max gross weight is 4318 pounds. The car weighs 2976 dry, so add coolant(2 gallons?), oil(2 gallons), gasoline(15 gallons), and a couple people(max cargo of 419 pounds of people and stuff). There seems to be a fudge factor in there for overloading(maybe by high speed driving?).
The point is, you only need enough pressure to carry the load. My fully loaded Spyder is about half the weight of my loaded Cayman. There might be 700 pounds on my entire front end of my Spyder, that's 350 pounds a tire. That's why the pressures are best run so low on these cars.
@Sacto Mitch, found a comparison less likely to be influenced by EPA:
2011 Lotus Elise Club Racer
Curb weight: 1878 lbs
Engine: 1598cc - 134hp - Located in front
Front tire: 175/55-16 - pressure 26 PSI
Rear tire: 225/45-17 - pressure 28 PSI
Fastest I ever went in a car was my 2nd time at Pocono NASCAR Drive Experience, With no speedo in the car but with the tach reading on the front straight somewhere around 150 mph and that brings an appreciation for 33 drivers that can push cars doing over 220 mph on that track.
@Sacto Mitch wrote: "I think car manufacturer tire pressure recommendations used to be based upon a mix of performance and comfortable ride back in the old days, but now they're based strictly on maxing out fuel economy."
Boy, have you got THAT right!
According to the door sticker in my Nissan Rogue mini-SUV, the official tires are Z-rated. That means they're rated for 160mph. I mean, really? On a diddly little 4-door passenger car?
Z rated tires are also wicked expensive. I talked the Town Fair Tire guys into selling me a set of H rated but both the door sticker AND the tire pressure gizmos inside the tires all want to see 36 - 40 psi so I run them at 36 and they give me a low pressure warning once in a while and I pump them up. The only reason I can see for 40 psi tires is better gas mileage, because the car has always ridden like a board. My wife's Outback rides much better than the Rogue.
@Michael Pickett posted:@Sacto Mitch, found a comparison less likely to be influenced by EPA:
2011 Lotus Elise Club Racer
Curb weight: 1878 lbs
Engine: 1598cc - 134hp - MID-ENGINE(rear)
Front tire: 175/55-16 - pressure 26 PSI
Rear tire: 225/45-17 - pressure 28 PSI
Fixed it for you!
Thanks, Danny. I appreciate the fix. I checked in on the Elise forums and even folks doing track days like tire pressures close to Lotus' recommendations. I think I may try 24/28 and see how it works on my speedster. I've been running 20/28 up to now.
The Lotus tire pressures are closer because the car is better balanced F-R.
Your Speedster has at least 60, but probably closer to 65% weight on the rear wheels, Mike.
The Elise is a very cool car. I'm trying to get a friend with one to bring it to Watkins Glen in a few weeks for the PCA DE.
The fastest I have ever driven a vehicle was 138 mph. This was NOT in my Speedster!
Speed is relative to me...and your comfort level is equally as important as the capability of the vehicle AND your skill level. I've had my VS up in the 100 mph range on more than one occasion just to see what she could do. I had plenty of room left to stretch it out in 4th gear (I have a fairly stout 2180) pulling well above 4000 rpm with room to go. That was on a straight road and I could feel the front end lifting a bit.
My most harrowing experience was in the foothills at maybe 60...I was accelerating into a left hand turn on a slight incline. As I hit the apex of the turn at the top of the rise the front wheels were turned left...but they had what felt like ZERO contact with the road. I got off the throttle quick, the front end settled down and the car made a hard left. To say it was exciting is an understatement!
Since that little burst of adrenaline I've entertained adding weight to the front beam...I've read ways to do that here on a different thread. I haven't made that update yet, but I have added some weight to the front end using tools, etc. I entertained adding diving weights down in the battery box but I'm convinced the weight will be too much for the floor to handle so my plan was to basically line the frunk near the wheel well / fuel tank with them. If I ever get around to doing that I'll post my findings.
.
Posting inflation numbers for other cars is a little apples and oranges, I think.
My old BMW 1600 was a ’68 (and was designed in the early ‘60s - as the 356 was ending production). Its suspension was light years more sophisticated. It did a far better job of keeping the wheels on the ground and in keeping them perpendicular to the road as they worked over the road surface.
The difference in how the car handled, how much grip was available at any time (on relatively skinny 165/70 tires), how ‘planted’ the steering felt, and in how predictable everything was at the limit was enormous compared to my Speedster. By any comparison, the swing axle and beam Speedster suspension is laughable. It’s clearly from another era.
Which isn’t to say it’s not still fun to drive at its limits, but if you’re used to driving modern cars quickly, you must realize these differences before firing up a Speedster or you’re courting disaster. I had a few puckering moments of my own when I first got the car which sobered me up right quick.
Lower pressures than we’re used to in modern cars will help to increase grip up front and help to counter the lack of weight there, but they won’t make the front feel like a 911 or any competent, modern car.
You simply must understand this about these cars, no matter what you might do to improve them. There are compromises ‘baked in the cake’, as Stan would say, that can’t be completely eliminated.
You can reduce the amount of ‘lightness’ and vagueness in the steering at speed on a rough surface, and you can learn how to handle it, and how far you can go before being in serious trouble, but you will never completely solve the problem without replacing the front suspension with a better design.
.
^ All of that. Every single word.
Our man, @Sacto Mitch: wordsmith, truth teller, funny guy, 5-speed owner, and male model.
Whoa...... "Male Model", too?
It must be that always-agreeable "California Weather".
Or something in the fish tacos.
Yeah..... That must be it.
Hmmm. In the old Orange Speedster we topped it out on I -80 at 133 mph. The car actually had lots of down force at that straight away speed. Not there were practically no cars on the road. It was a rush.
I did drive a Mclaren 570s at 170 mph.
And we just missed the Bonneville 200mph club in 2011 with a 198.35 mph run in a 1962 Pontiac tempest turbo ,injection
Thank you Jim Gilbert @Jim Gilbert - Madison, Mississippi adding the 26 pounds made huge differences! I drove easily now almost 80 miles hours!
Thank you all for the advice, next week they will re-align the tires and change the tires based on all the advice here above.
Carl
@Carlos P posted:Thank you Jim Gilbert @Jim Gilbert - Madison, Mississippi adding the 26 pounds made huge differences! I drove easily now almost 80 miles hours!
If you just added some weight to the battery box you might want to look at the archives. I have a modification to add steel weights to the front beam down low where it should be.
I have several projects in the archives that might be of interest. When I do something I post it.
Glad it worked for you.
