Jump to content
ThriftyT

Overdrive speeds

Recommended Posts

Just curious what speeds you guys with overdrive are comfortably holding on the highway.  And do you sustain those speeds for long trips, or give it breaks.   Thanks

Share this post


Link to post
Share on other sites

I run indicated 65 which is 63 on the GPS.  Will do 70 if needed for a burst.  More concerned about brakes.  Mostly stay on regular highways instead of interstates.

Edited by greg g

Share this post


Link to post
Share on other sites

My 41 windsor will cruise at 65 but has triple carbs ,twin exhausted and a split manifold ,it needs an overdrive really! On the other hand my 48 New Yorker will cruise all day and all night at a true 70 ,more if needed.The straight 8 is literally a quantum leap form the 6.

Share this post


Link to post
Share on other sites

I’ve been running mine at 70 and 75-80 at times.   It really feels like it is fine.  But got me thinking.   It sounds no more wrapped than a non overdriven car at 60.       Will be running it 7 hours to the Hot Rod Hill Climb at the end of the year, so I’m trying to find a comfortable sustainable speed.  (Will be traveling with bigger motors).  

Share this post


Link to post
Share on other sites

It all depends on the rear axle ratio, what type of terrain, mechanical condition of the drive train...tires, alignment etc.

I used to drive my 53 Savoy wagon with a 4.30 rear end 65- 70 on the freeways all the time...

You will quickly find out what seems a good feeling safe speed and the engine likes it.

Hills though can slow you down unless you KD.

I agree with normanpitkin on the straight eight cars...they are yearning to do 80 all day long....smooth and quiet.

A lot of excellent engineering.

Share this post


Link to post
Share on other sites

Upto 80% of peak HP rpm is easily sustainable.  Chrysler pulled engines at random off the line, bolted them up to a water brake dynomometer and ran them at 3600 against the load for 50 hours as part of their engine QC program.

 

run your numbers

 

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

Share this post


Link to post
Share on other sites

With given perfect conditions (engine, cooling, trans, overdrive, shocks...) my P23 makes 81 mph (130 kmh) with 2200 rpm for hours,

interrupted only by fill-ups :))

I don´t know gear ratios, but George Ashe had sent me "faster "gear wheels

On less than perfect roads the running gear is the limitation: you will get seasick!

Mine has a sway- bar, maybe it is even worse without!

And while reaching even 87 mph, You must remember the 60 mph brakes!!

Our constant travelling speed is75 mph, also the noise is more acceptable then.

Without overdrive riding is very uncomfortable in Germany´s today´s hectic traffic

Greetings!

Go

 

(all the speeds are speedometer readings! For GPS values take 10 % off)

Edited by Go Fleiter

Share this post


Link to post
Share on other sites

Mine will comfortably run all day at 70mph in overdrive, and it sits nicely in the power range to give a bit of acceleration when needed.
My car has a standard 3.9 rear end.

Edited by Robin (UK)

Share this post


Link to post
Share on other sites

65mph  for long stretches.I did have vapor-lock, last week after running on the freeway at 65 for a half hour, then cruising very slowly through a Residential area for my nieces birthday party.I have the heat shield between the manifold and the fuel line but I guess there wasn't enough air going over the engine compartment.We pulled over and waited a few minutes and it started right up.

Share this post


Link to post
Share on other sites
8 hours ago, Go Fleiter said:

. . .

On less than perfect roads the running gear is the limitation: you will get seasick!

Mine has a sway- bar, maybe it is even worse without!

 . . .

 

I added a rear sway bar, and KYB gas pressurized shocks, and it was a huge advantage on poor roads. My bar came from a '74 Thunderbird, and is now on my 2012 Toyota Tacoma*, but it's now quite a tight fit laterally. This makes me think the Helwig Tacoma kit would bolt right under a P23, as it will be a tad narrower than a P15.

 

The end links on my Tacoma had to be about the same length as the P15, though I changed the design for more clearance.

 

* I used the Thunderbird axle clamps, but made custom links in both cases. I had to re-shape the clamps slightly for the Toyota axle, but they work fine. I did remove a small stud on the clamps, which went to the FOMOCO spring seat. 

Share this post


Link to post
Share on other sites

My P15 cruises along nicely at 65-70mph in overdrive, has stock running gear and single carb for the mo..........

Share this post


Link to post
Share on other sites

What I remember was the OD trans was a bust for stoplight drag racing.

Like a boat anchor. Heavy, and more drag on the windup.

But on the freeway it was worth its (considerable!) weight in gold.

My P15 had increased compression, and easily pulled 80+ on the freeway.

Unless there was a headwind...

Edited by Ulu

Share this post


Link to post
Share on other sites
On 5/23/2020 at 2:56 PM, normanpitkin said:

My 41 windsor will cruise at 65 but has triple carbs ,twin exhausted and a split manifold ,it needs an overdrive really! On the other hand my 48 New Yorker will cruise all day and all night at a true 70 ,more if needed.The straight 8 is literally a quantum leap form the 6.

 

It's surely more than that!

A quantum is so teeeeny!

 

It is the smallest possible increase in energy.

 

Maybe that stupid TV show made people think it was something huge.

Share this post


Link to post
Share on other sites
On ‎5‎/‎24‎/‎2020 at 2:24 PM, Young Ed said:

My 218 with overdrive and 3.73 rear gears says I'd be going about 90 at 3200!

 

My 218 in 5th gear, 3.73 rear gear, I am doing 60 mph at 1800 rpm on near level highway..

I would never go 90, even if I could....

SAM_0050.JPG

Share this post


Link to post
Share on other sites
5 hours ago, Ulu said:

Pretty much everyone thinks it's a large increase not a small one ,a case of popular use being the very reverse of the actual meaning

.Ever hear of things being flammable or inflammable? Every day is a school day for everyone ...

ps. I liked that stupid tv show as did plenty of other people.5 seasons in the dog eat dog world of US television ,someone must have liked it!

Still ,thanks anyway

 

 

 

 

 

.

 

Edited by normanpitkin

Share this post


Link to post
Share on other sites

I recently swapped out my rear axle on my 53 from 3.90 gear s to 3.55.... previously 50 mph was the sweet spot ... now its 60 mph ...

when I finally get a Over Drive trans ... 70 mph will be easy 

Share this post


Link to post
Share on other sites
2 hours ago, derbydad276 said:

I recently swapped out my rear axle on my 53 from 3.90 gear s to 3.55.... previously 50 mph was the sweet spot ... now its 60 mph ...

when I finally get a Over Drive trans ... 70 mph will be easy 

 

But the brakes won't be any better.......    😃

Share this post


Link to post
Share on other sites
7 hours ago, normanpitkin said:

I liked that stupid tv show as did plenty of other people.

 

My wife never missed it, but I didn't have time for much commercial TV. In those years I was fixing up a boat.

 

Regarding the straight eights, I'd rather have one than any Hemi.

But I'd might as well wish for a pet unicorn.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.

Terms of Use