Driving our old cars at high speeds

[Plymouthy Adams]

this error I made has ragged me to no end in how I arrive at the conclusions..again I was crunching data on for my MG100 and wanting to go to the 3.1 rear ratio found in later models..now...I cannot find the site I was using at the time..

Edited February 9, 2013 by Plymouthy Adams

[T120]

Well ,Plymouthy -Some would say... going on 2000 years since the last pluperfect person walked this earth

Edited February 8, 2013 by Ralph D25cpe

[Plymouthy Adams]

Ralph if I make an bad post I surely will admit to it and do my best to set the record straight..last thing we need is folks trying to work with errounous info..I know I am not perfect in any sense of the word..

[T120]

And from you,Plymouthy - an example for others to follow

[1941Rick]

I would have a hard time going with any gears higher than 3:9.......just not enough power to run the hills. i have 3:9s in my car and going up over some of the passes in the Rockies you have to kick it out of OD, ( of course if you hit the bottom at 80 you might be OK ).

[bamfordsgarage]

...man is my face red...

[55 Fargo]

Had the Fargo out on the hwy today, went for about a 10 mile drive. It is mild out, so stayed away from salty roads, hwy was dry.

50 -55 ph like nothing, you can barely here engine at 45 mph, I have 3.23 gears.

I brought this old beast up to 60 mph, at 60 mph, things started to sing a bit. I would guess it would sound busy at speeds over 65 mph.

I really like the sounds of things at 55 or so, very quiet.

I did not want to go faster, my rims are not balanced, and the outer tie-rod ends, need to be replaced, creatinga little play up front.

I am quite happy the way this drives and runs. I am not sure I even need a 5th gear OD , witha 3.23 diff, might end up being a tad high for 5th od, on hills or windy days.

I have these old P 205 75 15 tires, that may be 26 inches tall, I should go with a tire up to about 28 inches, would make it even better.

Some pics

Edited February 10, 2013 by C38Spitfire6

[55 Fargo]

1 thing I have discovered is this. On my truck, tonight going down the highway, speeds from 30-45 mph, in 4th gear, with 3.23 rear gears, not much throttle response, after 50 mph lots of throttle response.

At 60 mph, could go a lot faster, how fast I do not know, but would say 80 mph would not be impossible.

Even with front end and steering work, that it needs, new tires, I do not think these type of trucks would be all that much fun barreling down the road at speeds over 65-70 mph. I see these units as 60 mph creatures, with stock suspension and steering, regardless what has been done gearing wise to enhance speed and lower rpm.

Tim I did this 20 mile drive tonight in the dark, it was fun, outside temp, about 18, love drivin this old girl better than my 47 especially at night, 12 volt lights are still better in my books too.....

[hansen]

Hey,new guy here.

Just want to say that with my De Soto 1941 i can cruise all day long in 60 m.p.h no problemas,this is an original car.

My Dodge 1948 seems to be going well at the same speed but i have only been driving it for a week so far.

[55 Fargo]

Hey,new guy here.

Just want to say that with my De Soto 1941 i can cruise all day long in 60 m.p.h no problemas,this is an original car.

My Dodge 1948 seems to be going well at the same speed but i have only been driving it for a week so far.

Have you verifed your speedo with a reliable "GPS"? I would venture to guess, either vehicle you have can handle sustained speeds at 60 mph, especially with an engine in good condition, but you want to make sure you can steer and stop, in the blink of an eye.

The Guys in parts of Canada and The USA, have huge vlumes of traffic on high speed freeways, and some in very hilly terrain. Add summer temps of 90 and over, and things can get heated up quickly too

[CanadianD25]

55 is the most I got mine up to.  The scary thing was the original suspension and bias ply tires.  Besides the horrible swaying, the engine sounded fine.  An old timer also told me not to exceed 55 either.

[55 Fargo]

55 is the most I got mine up to.  The scary thing was the original suspension and bias ply tires.  Besides the horrible swaying, the engine sounded fine.  An old timer also told me not to exceed 55 either.

Not sure if your in Canada, or just have a canuck built car.

Lots of ares in Canada you can get away with 55 mph or up here 90kmh, but if your around the bigger cities like Toronto, not so much fun perhaps on the 400,401 or QEW doing 90 kmh.

Your car probably has a 218 with 3.90 rear gears, so 55 would be wise if your steering and front end are so-so.

Good shocks,springs, radial tires can make a nice ride improvement...have fun motoring

[hansen]

Have you verifed your speedo with a reliable "GPS"? I would venture to guess, either vehicle you have can handle sustained speeds at 60 mph, especially with an engine in good condition, but you want to make sure you can steer and stop, in the blink of an eye.

The Guys in parts of Canada and The USA, have huge vlumes of traffic on high speed freeways, and some in very hilly terrain. Add summer temps of 90 and over, and things can get heated up quickly too

No Sir i own no GPS,Im looking at the speedometer.The De Soto engine was  restored  in 2003,Dodge 2006 no problems there.

Steering is fine,but i have to fix the brakes now on both cars.

[Adam H P15 D30]

When I drive my Dodge on the highway, I run it at 65 mph all day.  Car is stable and does not wander or feel out of control at all.  When in traffic I slow because of the brakes.  Mine is lowered a little with radial tires.  I'm not sure what all the fear about running these things at higher speeds is from????  EXCEPT IN HEAVY TRAFFIC.  If your front end needs work, just fix it so it will be safe!!!  No matter what kind of vehicle it is, it is not save to drive with a worn out front end!!  Just be mindful of the brakes and keep your distance!!!

[52b3b Joe]

When I drive my Dodge on the highway, I run it at 65 mph all day.  Car is stable and does not wander or feel out of control at all.  When in traffic I slow because of the brakes.  Mine is lowered a little with radial tires.  I'm not sure what all the fear about running these things at higher speeds is from????  EXCEPT IN HEAVY TRAFFIC.  If your front end needs work, just fix it so it will be safe!!!  No matter what kind of vehicle it is, it is not save to drive with a worn out front end!!  Just be mindful of the brakes and keep your distance!!!

 

Adam, I agree with you. 

 

 

I drive our 41 Desoto 65 mph comfortably on the freeways. In heavy traffic we will do 75 mph with it and it handles it fine, but that's for for a short time. Sometimes its safer to go faster with traffic. The front end is tight, good alignment, and we run new bias ply tires. The car has factory 3.73 gears. Stopping is the only limiting factor with our cars in my eyes. I feel pretty safe cruising at 65 mph with it. It handles good, drives very nice, and is comfortable at 65.  I have not driven my B3B on the road yet, so I can't speak for it, but with a fresh front end, good alignment, new bias ply tires, all new brakes, rebuilt engine and a rebuilt rear end, I think I'll be able to cruise 60 mph with the 4.11 rear end. Again I think stopping will be the limiting factor on the truck. The gearing will also hold it back some too, but I am planning on 3.73 gears in the future.

 

You just don't tailgate or do last minute stopping with these cars (or any car), and you drive defensive. Look beyond your front bumper and beyond the car ahead of you and think ahead. You have to know your own car and your limits to drive safely IMO. 

[Adam H P15 D30]

I kind of drive the old cars like I ride the motorcycles. Defensively

[Don Coatney]

I kind of drive the old cars like I ride the motorcycles. Defensively

I drive my P-15 like a rental. Full out!!

[Uncle-Pekka]

When I drive my Dodge on the highway, I run it at 65 mph all day.  Car is stable and does not wander or feel out of control at all.  When in traffic I slow because of the brakes.  Mine is lowered a little with radial tires.  I'm not sure what all the fear about running these things at higher speeds is from????  EXCEPT IN HEAVY TRAFFIC.  If your front end needs work, just fix it so it will be safe!!!  No matter what kind of vehicle it is, it is not save to drive with a worn out front end!!  Just be mindful of the brakes and keep your distance!!!

 

 

Adam, I agree with you. 

 

 

I drive our 41 Desoto 65 mph comfortably on the freeways. In heavy traffic we will do 75 mph with it and it handles it fine, but that's for for a short time. Sometimes its safer to go faster with traffic. The front end is tight, good alignment, and we run new bias ply tires. The car has factory 3.73 gears. Stopping is the only limiting factor with our cars in my eyes. I feel pretty safe cruising at 65 mph with it. It handles good, drives very nice, and is comfortable at 65.  I have not driven my B3B on the road yet, so I can't speak for it, but with a fresh front end, good alignment, new bias ply tires, all new brakes, rebuilt engine and a rebuilt rear end, I think I'll be able to cruise 60 mph with the 4.11 rear end. Again I think stopping will be the limiting factor on the truck. The gearing will also hold it back some too, but I am planning on 3.73 gears in the future.

 

You just don't tailgate or do last minute stopping with these cars (or any car), and you drive defensive. Look beyond your front bumper and beyond the car ahead of you and think ahead. You have to know your own car and your limits to drive safely IMO. 

 

Adam, Joe,

 

I agree with you in the matter of driveability of the suspension and brakes of these cars. Driving defensively there is no problem running these cars 60...70 mph. Also modern cars are all not alike, some heavier, some with different brakes, thus one need to know his car and drive accordingly.

 

However, the answer to Adam's question " I'm not sure what all the fear about running these things at higher speeds is from?" - is the engine and transmission:

In my case, running 4.1:1 rear end I would need to rev 3100rpm from the engine to reach 60mph...

Apart the noise (which is nowhere near comfortable) I am worried for the engine to throw a bearing.

These engines were not designed to run high revs: The components such as pistons, connecting rods and crankshaft are way heavier than modern engines.

Stroke/bore ratio is way higher than modern motors.

The lubrication is not as good as modern engines.

The materials were less spec than today's.

These are TORQUE engines vs. modern HIGH REV power motors -(Which in fact is just the thing I LIKE)

Thus this thread has been, what modifications we need to run that 60mph laid back easy manner.

3.73:1 rear end and tall radial tires will do the trick - 3.9 rear and OD even better.

Edited February 14, 2013 by Uncle-Pekka

[55 Fargo]

Adam, Joe,

 

I agree with you in the matter of driveability of the suspension and brakes of these cars. Driving defensively there is no problem running these cars 60...70 mph. Also modern cars are all not alike, some heavier, some with different brakes, thus one need to know his car and drive accordingly.

 

However, the answer to Adam's question " I'm not sure what all the fear about running these things at higher speeds is from?" - is the engine and transmission:

In my case, running 4.1:1 rear end I would need to rev 3100rpm from the engine to reach 60mph...

Apart the noise (which is nowhere near comfortable) I am worried for the engine to throw a bearing.

These engines were not designed to run high revs: The components such as pistons, connecting rods and crankshaft are way heavier than modern engines.

Stroke/bore ratio is way higher than modern motors.

The lubrication is not as good as modern engines.

The materials were less spec than today's.

These are TORQUE engines vs. modern HIGH REV power motors -(Which in fact is just the thing I LIKE)

Thus this thread has been, what modifications we need to run that 60mph laid back easy manner.

3.73:1 rear end and tall radial tires will do the trick - 3.9 rear and OD even better.

Pekka, could not agree more, if the engine and all components are in fine form, hey "fill your boots". nobody was driving these old beast at 70 mph at sustained speeds, back in 1948, for a number of reasons i suppose, highway type and quality for 1 reason.

I never tell people what to do, but everyone should verify their speedos too, with a reliable GPS, a lot of these old speedos are on the generous side too....happy motoring

[Robert Horne]

 

I kind of drive the old cars like I ride the motorcycles. Defensively

 

I have ridden motorcycles most of my like. Driving my vehicles defensively,

like I ride my mororbike, has saved my life many times. Here in Virginia,

this is "tailgate" country. Many times, I have to pull off the road,

or move to the high speed lane and slow down, to get someone off my butt.

[james curl]

The factory rated them at 3600 sustained rpm, supposedly for twenty four hours at a time.  I have a Dakota 3.55:1rear end in my 48 P-15 with an engine I assembled myself in 2007 and a friend and I took it on a 4800 mile trip to the west coast and back at speeds of 60 mph to 75mph on interstate 10 in west Texas which has an eighty mile per hour speed limit.  I routinely drive mine 70 mph every where I go on the highways in central Texas just to stay out of the way of the semis, so far no problems in 25000 miles of driving.  I do run radials and disc brakes on the car.

[TodFitch]

. . .

In my case, running 4.1:1 rear end I would need to rev 3100rpm from the engine to reach 60mph...

Apart the noise (which is nowhere near comfortable) I am worried for the engine to throw a bearing.

These engines were not designed to run high revs: The components such as pistons, connecting rods and crankshaft are way heavier than modern engines.

. . .

 

Max BHP is at 3600 RPM and, starting in the 20s or 30s, the design test was to run them at max BHP (wide open throttle at 3600 RPM) for 50 hours with no damage before releasing the design for production. It is my understanding that they also periodically pulled engines off the production line and tested them that way too. You should be able to run the engine all day, everyday at 3200 to 3300 RPM. Now if your engine is old and worn out you may have an issue. But if the engine is in reasonable condition, you should be able to run 65 MPH with stock gearing and stock tire size.

[BobT-47P15]

Several years ago, when I had some radial tires on the convert, I ran it up to around 70.  The motor was working some, but it

handled good.  Now I have bias ply tires and with the somewhat worn front end, it doesn't track and drive as well.  It does

better at about 55 or so.  Am having new (Ford pickup) type shock mounts installed......will see if that makes any notable

difference in the handling.  The radials WILL offset some play in the steering system and not wander due to ruts in the

road.  I find it enjoyable to just cruise along at a leisurely pace on a nice day. 

[Adam H P15 D30]

I also did a rear axle swap to 3.25.  I travel with my father and his (mine too) friends to some NSRA events around the state.  These guys are all "streetrodders" with modern drivetrains so they travel at the posted limit or above.  They do tolerate my 2nd gear hill pulls but I get my share of crap from them about it.  Part of the character of my vehicle is dealing with it's shortcommings.  I sometimes feel that gets lost when everything is fuel injected and air conditioned.  I still get the " you drove that Flathead from......." comments and it still makes me smile when I say yup.  Disc brakes are comming though.  I did notice how much better the vehicle stopped when the 8" Rear axle went in with modern rear brakes.

 

Adam

[55 Fargo]

Max BHP is at 3600 RPM and, starting in the 20s or 30s, the design test was to run them at max BHP (wide open throttle at 3600 RPM) for 50 hours with no damage before releasing the design for production. It is my understanding that they also periodically pulled engines off the production line and tested them that way too. You should be able to run the engine all day, everyday at 3200 to 3300 RPM. Now if your engine is old and worn out you may have an issue. But if the engine is in reasonable condition, you should be able to run 65 MPH with stock gearing and stock tire size.

Yes Todd, these were of course to be at the extreme end of tolerance, and Chrysler wanted to make sure the product was up to the call of duty.

I often wonder if combines, swathers, compressors, and other such heavy-duty equipment was operated at 3000+ rpm, don't think so, but do not know for sure. i have been told by a couple of older farm guys these machines were operated in the 2500 rpm range, possibly closer to the max torque curve. These machines also did  not cruise down a smooth road getting an air exchange through the rad like cars and trucks.

I would venture to guess these engines can handle much more, than their counterparts of the day,namely the stovebolt 6, and flathead V8.