rpm at 75?
Thread Starter
|
Elder User
Joined: Jul 2002
Posts: 526
Likes: 0
From: USA
rpm at 75?
ok i just got back to school and its about 400 miles. i drove a constant 80-85 mph the whole way, i got a c6 and 3.73 gears in the d60 rear. i only turn between 2500-2700 at 75 and 3000 at about a 1/4 inch past 85. this sounds a little low engine speed for the 3.73 rear, any ideas??
1977 F250 460
C6 Hedman Headers
Dual 40 series
edelbrock performer
holley 4160
msd 6a and blaster coil
1977 F250 460
C6 Hedman Headers
Dual 40 series
edelbrock performer
holley 4160
msd 6a and blaster coil
Posting Guru
Joined: Sep 2001
Posts: 1,531
Likes: 1
From: in the country
rpm at 75?
I think that either your tac is off and\or your speedo is wrong or maybe a combination of the two!!!!!!Especially , given the fact that you have a 10% slippage(assuming that number is accurate) which means that for purposes of explanation---say your rpm was 3000 at 70mph(not your actual numbers)--assuming a 1:1 ratio----with a 10% slippage your rpm would turnout to be---3,000\.9=3,333 if my division is accurate.........fd
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
rpm at 75?
[updated:LAST EDITED ON 03-Sep-02 AT 01:21 PM (EST)]You also can't accurately determine tire diameter by calculation using the tire size. To measure the size, do this:
Park the vehicle on a hard, level surface. Measure the distance between the ground and the center of the hub. This is the radius. Obviously, double it to get the diameter.
Now compare it to your calculated size, and you'll see what I mean.
Park the vehicle on a hard, level surface. Measure the distance between the ground and the center of the hub. This is the radius. Obviously, double it to get the diameter.
Now compare it to your calculated size, and you'll see what I mean.
Posting Guru
Joined: Sep 2001
Posts: 1,531
Likes: 1
From: in the country
Trending Topics
Thread Starter
|
Elder User
Joined: Jul 2002
Posts: 526
Likes: 0
From: USA
rpm at 75?
my tires dont give a size as to how tall they are, all they say is 9.50x16.5LT they are pretty big, i would guess close to or more than 30 inches. the tach isnt off because at idle it reads 650. and the speedo isnt off, unless it is very very small because when i drive by those police things that tell you how fast you are going, it is spot on.
1977 F250 460
C6 Hedman Headers
Dual 40 series
edelbrock performer
holley 4160
msd 6a and blaster coil
1977 F250 460
C6 Hedman Headers
Dual 40 series
edelbrock performer
holley 4160
msd 6a and blaster coil
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
Posting Guru
Joined: Oct 1999
Posts: 1,188
Likes: 0
From: yes
rpm at 75?
>What is your tire size? I'm turning more rpms than that with
>a 2.75 rear and 235/75/15 tires.
there's something wrong with your spedometer if your getting 3000RPM at 75mph. 4.10's with my 235/75/15's are 3000@60mph. My 4.10's+.68 overdrive= 2100RPM give or take for 60 or 3000RPM for 90mph
>a 2.75 rear and 235/75/15 tires.
there's something wrong with your spedometer if your getting 3000RPM at 75mph. 4.10's with my 235/75/15's are 3000@60mph. My 4.10's+.68 overdrive= 2100RPM give or take for 60 or 3000RPM for 90mph
Post Fiend
Joined: Feb 2000
Posts: 5,130
Likes: 8
From: Brea CA
rpm at 75?
>my tires dont give a size as to how tall they are, all they
>say is 9.50x16.5LT they are pretty big, i would guess close
>to or more than 30 inches. the tach isnt off because at
>idle it reads 650. and the speedo isnt off, unless it is
>very very small because when i drive by those police things
>that tell you how fast you are going, it is spot on.
>
>1977 F250 460
>C6 Hedman Headers
>Dual 40 series
>edelbrock performer
>holley 4160
>msd 6a and blaster coil
Hey that's a pretty good guess! Most 9.50X16.5LT tires measure between 30.6 and 31 inches in diameter when new.
Something ain't right though...
Barry
>say is 9.50x16.5LT they are pretty big, i would guess close
>to or more than 30 inches. the tach isnt off because at
>idle it reads 650. and the speedo isnt off, unless it is
>very very small because when i drive by those police things
>that tell you how fast you are going, it is spot on.
>
>1977 F250 460
>C6 Hedman Headers
>Dual 40 series
>edelbrock performer
>holley 4160
>msd 6a and blaster coil
Hey that's a pretty good guess! Most 9.50X16.5LT tires measure between 30.6 and 31 inches in diameter when new.
Something ain't right though...
Barry
Postmaster
Joined: Aug 2000
Posts: 3,312
Likes: 1
From: Eldorado Ca. USA
rpm at 75?
[link:http://www.4lo.com/geartable.html|here is the answer, go here]
Tony
'77 F250, 4X4 460 transplantee, "Flamer"
'74 F250. 460, "beater" now "1 dead ford"
'73 F250, "midnight auto" now a trailer for the flamer
Tony
'77 F250, 4X4 460 transplantee, "Flamer"
'74 F250. 460, "beater" now "1 dead ford"
'73 F250, "midnight auto" now a trailer for the flamer
Freshman User
Joined: Jul 2002
Posts: 31
Likes: 0
From: forest lake
rpm at 75?
I had a 300-6 with the 3spd OD non grany manual trans.The rear was stock ratio?
would drive 65-70 with out the od.
Od at 50-55 truck almost stalled out
3rd went up to 90-100
4th the 300 would only push it 125-130
plenty of gear left.
The look on the import owner punks face when he hears me up shift at 95 <evil laugh>HA HA HA
would drive 65-70 with out the od.
Od at 50-55 truck almost stalled out
3rd went up to 90-100
4th the 300 would only push it 125-130
plenty of gear left.
The look on the import owner punks face when he hears me up shift at 95 <evil laugh>HA HA HA
