The Ford Barn

Brobrian · 02-01-2012, 10:49 PM

Guys on the forum are always saying they drive their cars 50 to 60 miles/hour and feel their cars are cruising.

Well, I know we are comparing apples and oranges most of the time because of the variety of mods people have done to the engine, and rear end, not to mention those who have put in over-drives.

I have an an early '28 (AR) coupe which was bone stock until I put a different set of gears in the rear end a while back. (Can't remember the ratio). The car would go faster, but I still feel that 45 is the comfortable cruising speed.

My '31 pu has a lower ratio rear end and feels rushed at 45.

The engines in both cars run reasonably well, they just don't seem to like higher rpms.

How about the rest of you that are running stockers. Is 40 to 45 still too slow for a cruising speed. Should I be looking for a problem? Running 'em harder?

Colorado Greg · 02-01-2012, 10:56 PM

I have a '29 Coupe that is all stock with the 3.78 rear end. Betsy runs good and smooth @ 45mph but she has alot of throttle left. I will run her faster if I'm holding up traffic or something, then back down to 45 when I can.

I have had her up to 60mph but I didn't like the vibrations. I had to do it just to see if it would!

p.s. I live at 5800ft elevation.

Brobrian · 02-01-2012, 11:00 PM

wow, the only time my car ever breaks 55 is on a long steep down-hill in neutral. Looks like I'll have to go racing this w/e just to see if the speedo even has a 60.

dynaflash_8 · 02-02-2012, 03:33 AM

my 30 coupe also cruises at 45, but will only pull 60 down hill. Put me on any grade and its down to 27 mph

dr.j · 02-02-2012, 05:10 AM

45 to 47 MPH most of the time without watching the speedo. My Tudor just seems to like that speed. I punched it up to 62 once on level ground and felt she would have gone faster but we ran out of road. Checked with a GPS.

Smitty · 02-02-2012, 07:48 AM

Sponsored Links (Register now to hide all advertisements)

I have a good engine w/ high compression head and touring cam. With 3:78 gears it would do 60 no problem but there was vibration and I am sure it was tough on the engine,
I installed 3:54 gears and it helped a little to ease the vibration. I have now installed a Mitchell and shift down at around 45 mph. I can cruise at 50-55 no problem and the balance of the Mitchell drive line runs smoother even when out of OD. It makes the coupe a lot more comfortable and enjoyable to drive.
This is a daily driver and travels extensively.

Steve

BRENT in 10-uh-C · 02-02-2012, 08:03 AM

BroBrian, I think where a lot of this confusion comes is the difference between someone saying "I drive my car 45 mph." vs. someone saying "A Model A will only run 45 mph and anything faster is unsafe." If you only feel comfortable driving your car 45, then that is a perfectly acceptable speed for you. I also think your locale and driving conditions largely dictate what should be a safe speed however confidence in your car should be the utmost priority. I think knowing that your brakes and steering are within factory specifications will give you that confidence.

Brobrian · 02-03-2012, 08:40 PM

Brent,
Yeah, maybe, but I personally feel the car is cruising at 45. It's running with less vibration, the gas mileage is steady, doesn't overheat etc. So, it's not just a subjective thing. I've run my car up to 55, but there's no way in hell I'd keep it up for long. I'd be asking for trouble.
I guess what I'm looking for could only be learned by driving another stocker that, as you say, is perfectly up to spec. in other words, "like new." If it turned out that the other car really ran so much better than mine at 55+, I'd have to conclude that my car was somehow worn and in need of help. It's just hard to imagine that other stock cars are running at that high an rpm and not being pushed to the limit.

Fred K-OR · 02-03-2012, 09:36 PM

My coupe's speedo says I am going 50 or 55 MPH-wow! But--my GPS says it is only 40 MPH or so! Looks like the old speedo needs some work.

Tom Wesenberg · 02-03-2012, 09:40 PM

Quote:

Originally Posted by Fred K-OR

My coupe's speedo says I am going 50 or 55 MPH-wow! But--my GPS says it is only 40 MPH or so! Looks like the old speedo needs some work.

Check the odometer for accuracy first. Once that is accurate, then check the speed. It might be a wrong gear for the cable.

Fred K-OR · 02-03-2012, 09:58 PM

Tom, what do you mean "wrong gear for the cable"?? Are you talking about the gear on the drive shaft? It is a 19 tooth and if I remember that checks with my rear end ratio.

Tom Wesenberg · 02-03-2012, 10:35 PM

Quote:

Originally Posted by Fred K-OR

Tom, what do you mean "wrong gear for the cable"?? Are you talking about the gear on the drive shaft? It is a 19 tooth and if I remember that checks with my rear end ratio.

That sounds correct, but I like to check my miles against a known mile. My Olds is very accurate, so I mark off a mile with it and drive the Model A the same distance to compare.

Your speedometer probably needs to be lubed and may need adjustment.

Fred K-OR · 02-03-2012, 11:00 PM

Thanks Tom. Will get around to working on it a little later. Have a number of other things to get done first.

Brobrian · 02-03-2012, 11:36 PM

So what is the ratio in a stock rear end? No doubt not as simple a question as it sounds. Seems my pickup is geared lower than the coupe was even before I changed it.

Tom Wesenberg · 02-03-2012, 11:38 PM

3.78 is standard for the cars. Your pickup might have 4.11.

Brobrian · 02-03-2012, 11:58 PM

Ahh, that's why when my son and I went for a spin ( race) the other day, the car was slower off the line

but drove right by the truck until we hit the hill. It was a dead heat on the "speed-coast" back down, however. Loads of fun, but the two A's performed very differently. Even so, neither one reached more than 52 ish.

Peter J · 02-04-2012, 12:09 AM

Today I took mine out for sea trials with a stock B I just installed. Ran smooth but I kept reaching for higher gear. It really started winding up at anything faster than 45. Just about what it did with my A engine. I heard that their were different ratios for different areas of the country (mountain west vs. midwest?) and had a stamping on the banjo??

Marco Tahtaras · 02-04-2012, 12:38 AM

Quote:

Originally Posted by Brobrian

Ahh, that's why when my son and I went for a spin ( race) the other day, the car was slower off the line

but drove right by the truck until we hit the hill. It was a dead heat on the "speed-coast" back down, however. Loads of fun, but the two A's performed very differently. Even so, neither one reached more than 52 ish.

There can be numerous "tune-up" type issues that will limit your speed as described but is more often than not at least partially cam related whether just badly worn or reground. I've rarely driven less than 55mph on the highway and usually faster. My original Fordor has been a bit odd for me. When I relax it just settles in at 53mph. It doesn't matter whether I start out at 50 or 58 I soon find I'm cruising at 53 without thinking about it. I've done thousands of miles at 60mph in a bone stock Model A.

MN Stumpjumper · 02-04-2012, 05:28 AM

I have seen several threads disscussing "speed driven". I know most don't have tachometers,but I am wondering what RPM's these motors are running at the speeds given. What is the "perfect RPM" on these motors?

sukhoi · 02-04-2012, 08:20 AM

Most A's have a "sweet spot', a speed at which the car runs smooth without excessive vibration. As many have pointed out there are many reasons why. Bottom line, the car is talking to you and we should listen. Personally, I beleive that an addition of overdrive is the easiest way for higher highway speeds.

02-01-2012, 10:49 PM	#1
Brobrian Senior Member Join Date: Jan 2012 Location: Riverside, CA Posts: 315	Rear End Ratio Guys on the forum are always saying they drive their cars 50 to 60 miles/hour and feel their cars are cruising. Well, I know we are comparing apples and oranges most of the time because of the variety of mods people have done to the engine, and rear end, not to mention those who have put in over-drives. I have an an early '28 (AR) coupe which was bone stock until I put a different set of gears in the rear end a while back. (Can't remember the ratio). The car would go faster, but I still feel that 45 is the comfortable cruising speed. My '31 pu has a lower ratio rear end and feels rushed at 45. The engines in both cars run reasonably well, they just don't seem to like higher rpms. How about the rest of you that are running stockers. Is 40 to 45 still too slow for a cruising speed. Should I be looking for a problem? Running 'em harder? __________________ Forty horses is plenty.

02-01-2012, 10:56 PM	#2
Colorado Greg Senior Member Join Date: May 2010 Location: Littleton, Colorado Posts: 241	Re: Rear End Ratio I have a '29 Coupe that is all stock with the 3.78 rear end. Betsy runs good and smooth @ 45mph but she has alot of throttle left. I will run her faster if I'm holding up traffic or something, then back down to 45 when I can. I have had her up to 60mph but I didn't like the vibrations. I had to do it just to see if it would! p.s. I live at 5800ft elevation. __________________ "Betsy doesn't leak oil - she just marks her spot"

02-01-2012, 11:00 PM	#3
Brobrian Senior Member Join Date: Jan 2012 Location: Riverside, CA Posts: 315	Re: Rear End Ratio wow, the only time my car ever breaks 55 is on a long steep down-hill in neutral. Looks like I'll have to go racing this w/e just to see if the speedo even has a 60. __________________ Forty horses is plenty.

02-02-2012, 03:33 AM	#4
dynaflash_8 Member Join Date: Jul 2011 Location: Auburn WA Posts: 73	Re: Rear End Ratio my 30 coupe also cruises at 45, but will only pull 60 down hill. Put me on any grade and its down to 27 mph

02-02-2012, 05:10 AM	#5
dr.j Senior Member Join Date: May 2010 Location: Portland, ON, Canada Posts: 315	Re: Rear End Ratio 45 to 47 MPH most of the time without watching the speedo. My Tudor just seems to like that speed. I punched it up to 62 once on level ground and felt she would have gone faster but we ran out of road. Checked with a GPS. __________________ Dave A Jamieson Portland, ON Canada 1928 Tudor

02-02-2012, 07:48 AM	#6
Smitty Senior Member Join Date: May 2010 Location: Boston North Shore Posts: 753	Re: Rear End Ratio Sponsored Links (Register now to hide all advertisements) I have a good engine w/ high compression head and touring cam. With 3:78 gears it would do 60 no problem but there was vibration and I am sure it was tough on the engine, I installed 3:54 gears and it helped a little to ease the vibration. I have now installed a Mitchell and shift down at around 45 mph. I can cruise at 50-55 no problem and the balance of the Mitchell drive line runs smoother even when out of OD. It makes the coupe a lot more comfortable and enjoyable to drive. This is a daily driver and travels extensively. Steve

02-02-2012, 08:03 AM	#7
BRENT in 10-uh-C Senior Member Join Date: May 2010 Location: Eastern Tennessee Posts: 11,972	Re: Rear End Ratio BroBrian, I think where a lot of this confusion comes is the difference between someone saying "I drive my car 45 mph." vs. someone saying "A Model A will only run 45 mph and anything faster is unsafe." If you only feel comfortable driving your car 45, then that is a perfectly acceptable speed for you. I also think your locale and driving conditions largely dictate what should be a safe speed however confidence in your car should be the utmost priority. I think knowing that your brakes and steering are within factory specifications will give you that confidence. __________________ . BRENT in 10-uh-C . www.model-a-ford.com ...(...Finally Updated!! ) .

02-03-2012, 08:40 PM	#8
Brobrian Senior Member Join Date: Jan 2012 Location: Riverside, CA Posts: 315	Re: Rear End Ratio Brent, Yeah, maybe, but I personally feel the car is cruising at 45. It's running with less vibration, the gas mileage is steady, doesn't overheat etc. So, it's not just a subjective thing. I've run my car up to 55, but there's no way in hell I'd keep it up for long. I'd be asking for trouble. I guess what I'm looking for could only be learned by driving another stocker that, as you say, is perfectly up to spec. in other words, "like new." If it turned out that the other car really ran so much better than mine at 55+, I'd have to conclude that my car was somehow worn and in need of help. It's just hard to imagine that other stock cars are running at that high an rpm and not being pushed to the limit. __________________ Forty horses is plenty.

02-03-2012, 09:36 PM	#9
Fred K-OR Senior Member Join Date: May 2010 Location: Stayton, Oregon Posts: 3,806	Re: Rear End Ratio My coupe's speedo says I am going 50 or 55 MPH-wow! But--my GPS says it is only 40 MPH or so! Looks like the old speedo needs some work. __________________ Fred Kroon 1929 Std Coupe 1929 Huckster

02-03-2012, 09:58 PM	#11
Fred K-OR Senior Member Join Date: May 2010 Location: Stayton, Oregon Posts: 3,806	Re: Rear End Ratio Tom, what do you mean "wrong gear for the cable"?? Are you talking about the gear on the drive shaft? It is a 19 tooth and if I remember that checks with my rear end ratio. __________________ Fred Kroon 1929 Std Coupe 1929 Huckster

02-03-2012, 11:00 PM	#13
Fred K-OR Senior Member Join Date: May 2010 Location: Stayton, Oregon Posts: 3,806	Re: Rear End Ratio Thanks Tom. Will get around to working on it a little later. Have a number of other things to get done first. __________________ Fred Kroon 1929 Std Coupe 1929 Huckster

02-03-2012, 11:36 PM	#14
Brobrian Senior Member Join Date: Jan 2012 Location: Riverside, CA Posts: 315	Re: Rear End Ratio So what is the ratio in a stock rear end? No doubt not as simple a question as it sounds. Seems my pickup is geared lower than the coupe was even before I changed it. __________________ Forty horses is plenty.

02-03-2012, 11:38 PM	#15
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: Rear End Ratio 3.78 is standard for the cars. Your pickup might have 4.11.

02-03-2012, 11:58 PM	#16
Brobrian Senior Member Join Date: Jan 2012 Location: Riverside, CA Posts: 315	Re: Rear End Ratio Ahh, that's why when my son and I went for a spin ( race) the other day, the car was slower off the line but drove right by the truck until we hit the hill. It was a dead heat on the "speed-coast" back down, however. Loads of fun, but the two A's performed very differently. Even so, neither one reached more than 52 ish. __________________ Forty horses is plenty.

02-04-2012, 12:09 AM	#17
Peter J Senior Member Join Date: Jul 2010 Location: Olympia, WA Posts: 691	Re: Rear End Ratio Today I took mine out for sea trials with a stock B I just installed. Ran smooth but I kept reaching for higher gear. It really started winding up at anything faster than 45. Just about what it did with my A engine. I heard that their were different ratios for different areas of the country (mountain west vs. midwest?) and had a stamping on the banjo??

02-04-2012, 05:28 AM	#19
MN Stumpjumper Senior Member Join Date: May 2010 Posts: 203	Re: Rear End Ratio I have seen several threads disscussing "speed driven". I know most don't have tachometers,but I am wondering what RPM's these motors are running at the speeds given. What is the "perfect RPM" on these motors?

02-04-2012, 08:20 AM	#20
sukhoi Member Join Date: Aug 2011 Posts: 47	Re: Rear End Ratio Most A's have a "sweet spot', a speed at which the car runs smooth without excessive vibration. As many have pointed out there are many reasons why. Bottom line, the car is talking to you and we should listen. Personally, I beleive that an addition of overdrive is the easiest way for higher highway speeds.