A question about top speeds

[normanpitkin]

I had the inclination to see just how fast my 1948 Chrysler New Yorker would go yesterday ,I got her up to 80 on the speedometer and it still had a bit more to give ,bearing in mind the speedo is probably 10% out ,I reckon the true top speed is about 75/80 depending on road conditions. Has anyone else tried this and what speed did you get? I'm not particularly interested in any comments regarding brakes or tyres or safety issues ,those are topics for a different post.

[Plymouthy Adams]

speeds of that degree is easily reached and sustained but I do not like the floaty boat of the dampened a-arms and will one day change this to relocating the upper mount to the chassis, meanwhile 75 is pretty dang steady and comfortable speed...mine is a 230, automatic and runs a 3.73 and will shift into high at 50+ just putting your foot down on the pedal.  Way more civilized that that 3 on the tree garbage....shifter belong on the floor between bucket seats.....!!!!!

[knuckleharley]

9 minutes ago, normanpitkin said:

I had the inclination to see just how fast my 1948 Chrysler New Yorker would go yesterday ,I got her up to 80 on the speedometer and it still had a bit more to give ,bearing in mind the speedo is probably 10% out ,I reckon the true top speed is about 75/80 depending on road conditions. Has anyone else tried this and what speed did you get? I'm not particularly interested in any comments regarding brakes or tyres or safety issues ,those are topics for a different post.

My uncle used to own a 48 Chryser,and the top speed seemed to be about 20-25 MPH. I used to sometimes catch a ride to the nearest grocery store (about 20 miles one way),and at times was tempted to just get out and walk.

 

Seemed like that was the top speed of everything he owned.

[Dodgeb4ya]

I have had my 48 convert to 80 also.

70 is a smooth easy speed for it...

Reaching 80 was no problem.

The 70 year old man who owned it before me said he drove it from Seattle to Reno at speeds up to 80....said that was easy for the car.

These flathead eights can handle teasonably high speeds on long trips.

3.36 rear end ratio with 8.20 X 15 tires.

[Sniper]

I got my 51 up to 65 and got off the very next exit, too floaty for me.  Later found out the front shocks were bad.  Tie rod ends were a bit loose and the king pins were sloppy.  All that is fixed now and once I get my brakes bled and a few other issues sorted, this weekend I hope, we will try again.  IIRC, the top speed of my 51 when it was new was around 80. 

[LazyK]

a quick RPM to MPH calculation says says a engine RPM of 4000 (I would assume the upper limit of these flat heads) 3.91 final drive(1-1 transmission final drive and 3.91 rear end gearing), and a 28 in tall tire would  net a top speed of 85.2 miles per hour. A taller tire would increase this, a lower final drive(bigger numerically) would decrease it. 

 

dodgeb4ya's

example above tire 8.20x15 is 29.56 tall, 3.36 final drive, 80 mph  engine would have been 3057 RPM. I would assume a very reasonable RPM for extended time.

[TodFitch]

I got my '33 Plymouth up to 70 MPH (per my cellphone GPS app) once. Took a long time and could not hold it on even a slight upgrade. Biggest thing I noticed was my talkative passenger went quiet.

[dwest999]

TodFitch, lol... so that's the best way to silence a chatty Kathy sitting next to you... thanks for the tip.

[Loren]

According to  automobile-catalog.com the theoretical top speed was 85 mph.

 

However, a July 1949 Mechanix Illustrated test by Tom McCahill said, "When I was through with the ruff stuff we headed for some open stretches and speed runs. The Chrysler is fast and has a top actual speed of 96.5 mph...." (He was referring to the 1949 model of course but I can't imagine there was much difference and he said as much) "These cars are not radically different from the former Chrysler models in any important way."

 

So who ya gonna believe? You just might have to do an experiment, he he he!

 

In my younger days we'd head to El Mirage Dry Lake for an SCTA meet and get a real honest to goodness Timing Slip from my buddy Julian Doty. Which was much cheaper than a speeding ticket! If you joined a club, paid dues and performed a duty at the Lakes, you'd get a Brass Timing Tag to screw to your dash board! The black enamel ones were just the speed you went and the date you did it. The Red ones indicated you set a record.

[Tom Skinner]

I got my 1948 Royal up to 68mph with a 251 cu. in. in it. It sounded good but I do not want to push it.

It likes 50 -58 mph on a normal country road jaunt.

Tom

[Eneto-55]

7 hours ago, knuckleharley said:

My uncle used to own a 48 Chryser,and the top speed seemed to be about 20-25 MPH. I used to sometimes catch a ride to the nearest grocery store (about 20 miles one way),and at times was tempted to just get out and walk.

 

Seemed like that was the top speed of everything he owned.

Reminds me of a childhood memory.  We were in the last 1/4 mile stretch on the way to my grandparents, a dirt road.  (Yeah, DIRT.  Western Oklahoma, Garfield County. Shale road, actually, but it doesn't last too long before it turns into just plain old red dirt.)   I complained that my Dad was driving too slow.  I commented that I could walk faster.  My dad stopped the car & said OK, get out & walk.  He raced off, and I ran behind, in the dust cloud.  When I ran into the yard I was so mad a picked up a hand full of dust & sand and threw it at the car.  Let's just say that didn't go well with Dad.

 

But the first time we took that car there, Dad needed to find out how fast it would go.  81 is what I remember seeing from the back seat.  Oh, I didn't say.  It was a 53 DeSoto flat head 6.  (An older couple in our congregation had the same model, but with the Hemi.)

[knuckleharley]

1 hour ago, Loren said:

 

 

In my younger days we'd head to El Mirage Dry Lake for an SCTA meet and get a real honest to goodness Timing Slip from my buddy Julian Doty.  

Color me "Eaten alive with envy". I have never even been within 500 miles of El Mirage,but have been wanting to go since the days of the "little" Rod and Custom magazine.

[Loren]

My Dad had been going there since before the war. He said lots of guys got killed on the way up there and his Mom really didn't like him going.

In those days he said he'd take a Model T up there, set the steering wheel in a gentle circle and crawl into the back seat for a nap. The car would turn circles for hours because there is no self centering in a Model T. You have to turn the steering wheel both directions!

 

I got a driving lesson from the late Tom Beatty (P38 Drop Tank, last seen at the Henry Ford Museum) that I used to great effect and pissed my Dad off good.

When the race cars drive over the lake bed at speed, they tear it up and put up a "Roaster Tail" of dust as they go. So all this horse power leaves a layer of dust and marbles on the course. The later you run the greater the amount of loose stuff is under your wheels. The "slippage" can be around 12%! We'd drive the same car on different runs and I would always let him drive first. When I drove I would pull away from the start line and when there was a goodly amount of dust behind me I would move over as close to the cones as I dared. Nobody drove that close so it was like getting the first run of the day and I always went faster than he did. He never did figure out how I "cheated"!

The first couple of times he chalked it up to a Tail Wind but after a while he knew I couldn't be that lucky. After that I had to be Cheating. I just told him I knew a shortcut. Which of course is non-sense, so then I told him it was driver technique...which it was.

[knuckleharley]

Another "my uncle" (same one) true story related to how slow he drove,and this time it was in a mid-50's 1/2 ton Dodge pu. The ONLY new vehicle he ever bought in his entire life.

 

His son,my cousin, had enlisted in the army,and was a member of the 101st Airborne Division when he decided he didn't want to be in the army anymore,so he just came home. His mother and father finally talked him into going back to Ky to face his charges,so they all piled in the cab of that pu,and left northeastern NC for Ft. Campbell,Ky.

 

It needs to be said that although my aunt was a tiny woman, Uncle George was around 6'8'' tall,and his son "Mackey" was about the same size,so you KNOW that was a fun trip in the cab of that little truck at 35 mph.

 

Anyhow,they got to the main gate at Ft.Campbell,Mackey surrendered to the MP's,and they watche him getting hauled off to the stockage in handcuffs before turning around to dive back home to NC.

 

Imagine their surprise when they finally got home and discovered  Mackey sitting in their living room watching tv. This time they didn't have to go anywhere. The army sent some MP's to pick him up.

 

I once watched Uncle George pick up a flat 6 mopar engine complete to the bellhousing,and sit it in the bed of that pu. Didn't even grunt. He  just reached down,picked it up,and set it in the bed.  He was in his 60's,then. When he was in his 70's,I went up to "the ditch" were all the commercial fishermen kept their work boats,to pump out my fathers boat after a big rain storm,and uncle George was taking the 6 cylinder Falcoln engine out of his boat because it had thrown a rod. The ditch bank was probably 3 feet higher than the top of the 22 foot skiff,so I asked him if he needed any help.

 

He said."Nope,I think I got it.",and just reached down and picked it up and threw it up on the bank. His hands were so big he could palm a basketball.

 

Nobody ever saw him get mad,but then again,most people had better sense than to mess with anyone that large. Also,if he ever took a drink of alcohol,I never talked with anyone who witnessed it,and my father knew him when they were both boys. His first job was as a cabin boy at age 13 on a 3 masted sailing ship that traded with China. He ran away from home to get the job. He was gone for around 20 years before coming back home to live.

 

My very first job was as the only deck hand on the 38 foot shimp boat he build. Never worked that hard on any other job I ever had,but I made pretty good money for a punk 13 year old school child. I was never again temped to work on a shrimp boat,either. After that I wroked construction jobs as a helper ashore while I was still in school.

 

 

Edited December 24, 2021 by knuckleharley

[greg g]

Mine has seen several bursts to indicated 75.   This with the 4.11 rear end.  Haven't tried it with the od engaged.  Usually cruise 55 to 60.  When rebuilding this engine, I asked the machinest about peak rpm for long engine life,  he said most of these long stroke motors are fine to 80 to 85 % of the listed rpm where the factory rated peak hp. So since most of these engines in cars were rated at 3600, you would be looking at 3200 to 3300 as a sustainable rpm assuming everything is as it was meant to be inside the engine.

 

When I did my chassis dyno pull, my calculation with the 225 75 15 tire diameter suggested my limit was 3300 rpm.   The dyno instruments showed that 62 mph was arrived at 3280 rpm with those tires and the 4.11 gears. So 3300 would be 63/64 over the road.  

 

Have since calculated that the od drops that by apx. 900 rpm or 2400 give or take for 60 ish plus or minus.  If when we need to jump on the interstate, she goes up to indicated 65.  Nearly everyone else  is going 10 over or more, so we keep our limited access miles to aminimum, as folks don't pay much attention to overtaking peed differences these days.

 

Top speed, don't know probably wouldn't pull 3600 in od, might make 4000 in third So 75 maybe?

[Eneto-55]

He doesn't remember this the same as I do, but my younger brother had a 53 Cranbrook back around 1980.  (I reckon Yankees would say "back in the day".  Drives me nuts.  Like in Minnesota - lived there for 3 1/2 years during college months - they say stuff like "You want to go with?"  What what, I'm thinking every time.  But then where I come from we would say "You wanna' go 'long?"  Oh well.)  So, the 53 Plymouth.  He says he never did this, but one day he said (to my recolection) "Let's go for a ride.  I'm gonna' see if I can blow this engine."  It had one bad crank bearing - actually the previous owner had built it that way - didn't want to spend more cash on it.  So we go out on the highway and he wraps it up in second gear.  The poor thing is screaming, but it wouldn't blow.  Scrapped the car later, but he still has that engine.  I've heard of other people trying to blow one of these, too, and they say it's about impossible.  'Course my 49 P15 came with a blown engine - hole in the side of the block, so obviously it happens.

Edited December 24, 2021 by Eneto-55

[Dan Hiebert]

Fastest I've had the ol' D24 has been 65 on the recently repaved Interstate.  I don't dare go that fast on the secondary roads any place we've lived due to road condition.  Suspension, except shocks, is original.  Engine was rebuilt long before we got the car and could use another going over.  Does not have much trouble getting there, and seems to have more in her, but the noises she always makes crescendo as I speed up to the point I don't want to go any faster.  Nothing that doesn't sound right, just an old car making noise (kinda like me).  Although, much quieter and less "exciting" once we put radials on her.  I believe top speed cited by the factory for the D24s was right around 95 mph, I seem to recall reading that in an official tome sometime in the past, which to me is impressive - there's only so much a 102 hp engine can do in a car with the aerodynamics of a chicken coop.   

[keithb7]

I know my speedo reads 5 mph slow. I’ve had my ‘38 Chrysler coupe up to 65 or so. It has a 251 engine in it.  I know it’ll go faster. It has a 3 speed  plus overdrive.  3:90 crown & pinion. It gets a little loose feeing and float-y for my liking. Stock 6.00x15 bias tires. Pretty small tire footprint on the road.  That’s about as fast as I’ll ever take it.  

Edited December 26, 2021 by keithb7

[laynrubber]

Coming back from a car show couple summers ago I was tired so Mrs swapped driving with me. Half an hour later I woke up to us passing cars on the divided hwy. Mrs has a led foot and the needle was bouncing over 80 …..OVERDRIVE BAAAAABY.

[Bryan G]

There aren't many places around home to run over 60-65 but one bypass lets me crank it higher. I've topped 70 in my 49 New Yorker and, as expected, the engine didn't feel like it was breathing hard at all. The chassis, though? The "floats" kick in. I suspect with radials and modern shocks, maybe some other tweaks, 85 should be fairly easy. But on old bias plies and 70's Kmart shocks...

 

I've been driving this car a lot; my impression is that this really is a "highway" car and for its day it was quite the turnpike cruiser.

[Dodgeb4ya]

The 1946-48 Chrysler eight cars handle much much better than the 1949-50 Chrysler eight cylinder cars....not sure why.

I have both and have had a few others.

[DavidJose1]

On 12/23/2021 at 5:38 PM, Loren said:

My Dad had been going there since before the war. He said lots of guys got killed on the way up there and his Mom really didn't like him going.

In those days he said he'd take a Model T up there, set the steering wheel in a gentle circle and crawl into the back seat for a nap. The car would turn circles for hours because there is no self centering in a Model T. You have to turn the steering wheel both directions!

 

I got a driving lesson from the late Tom Beatty (P38 Drop Tank, last seen at the Henry Ford Museum) that I used to great effect and pissed my Dad off good.

When the race cars drive over the lake bed at speed, they tear it up and put up a "Roaster Tail" of dust as they go. So all this horse power leaves a layer of dust and marbles on the course. The later you run the greater the amount of loose stuff is under your wheels. The "slippage" can be around 12%! We'd drive the same car on different runs and I would always let him drive first. When I drove I would pull away from the start line and when there was a goodly amount of dust behind me I would move over as close to the cones as I dared. Nobody drove that close so it was like getting the first run of the day and I always went faster than he did. He never did figure out how I "cheated"!

The first couple of times he chalked it up to a Tail Wind but after a while he knew I couldn't be that lucky. After that I had to be Cheating. I just told him I knew a shortcut. Which of course is non-sense, so then I told him it was driver technique...which it was.

Dear ma’am, you seem to know a ton, do you know if the steering shaft where the splines are for a 50s plymouth would be the same as the later 60s cars?

[Loren]

I don’t know about steering wheel splines, sorry. I do know they rarely change.