|
|
Joined: Nov 2007
Posts: 3,620 Likes: 5
ChatMaster - 3,000
|
OP
ChatMaster - 3,000
Joined: Nov 2007
Posts: 3,620 Likes: 5 |
My '50 convertible has been running about 15-20 mph slow on the speedo. A few weeks ago the cable broke, so I ordered a new one from Chev's of the Forties and installed it. I was hoping that would fix the problem, but it didn't. The cable is oiled and turns free.
So my question is... where will the problem lie. Is there an adjustment that can be made on the speedo, or is it a problem in the transmission?
Thoughts?
Those accustomed to the finest...find it in Chevrolet.
1953 Belair Convertible
1951 2dr Deluxe Sedan
2015 GMC SLE 4X4
|
|
|
|
|
Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
|
|
ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
My educated guess is the head needs cleaning, lubrication, and recalbritation. I assume 3.55 gears were not installed and the speedo. gears not changed.
Gene Schneider
|
|
|
|
|
Joined: Nov 2007
Posts: 3,620 Likes: 5
ChatMaster - 3,000
|
|
OP
ChatMaster - 3,000
Joined: Nov 2007
Posts: 3,620 Likes: 5 |
The rear end was changed, but I thought that should only knock about 5mph off... not 15+...
I was mostly worried that something could go wrong at the tranny end. Are you saying I'm Okay there?
Those accustomed to the finest...find it in Chevrolet.
1953 Belair Convertible
1951 2dr Deluxe Sedan
2015 GMC SLE 4X4
|
|
|
|
|
Joined: Jan 2002
Posts: 1,069 Likes: 9
ChatMaster - 1,000
|
|
ChatMaster - 1,000
Joined: Jan 2002
Posts: 1,069 Likes: 9 |
If you have a GPS check it that way. I thought my 48 was off, but with the GPS it was right on. Someone just posted about that somewhere. Will see if I can find it. Found it Chev Gene posted it on Chevy Talk. http://www.chevytalk.org/fusionbb/showtopic.php?tid/288199/post/new/#NEW The 3.70 will slow the engine down 10%, dosen't sound like much but will make a world of difference. The 3.55 will slow down the engine 15% and hill climbing, especially under 50 MPH will be much slower. I have a 3.73 in my '39 and 65 to 70 MPH is a breeze.
1946 Chevy 3100 1/2 Ton Pickup Purchased 11/18/17 Sold 9/20
1948 Chevy Fleetmaster Coupe, Purchased 6/20/2010
1965 Chevy ll 350 Purchased Feb 2021. 3-speed Saginaw Hurst Floor Shifter 3.08 Rear End
2019 Ford Ranger Lariat Super Crew
|
|
|
|
|
Joined: Oct 2004
Posts: 535
Oil Can Mechanic
|
|
Oil Can Mechanic
Joined: Oct 2004
Posts: 535 |
I am in the process of modifying the 3.55 speedometer gears from a Powerglide transmission to fit a 3 speed. Is any one interested if I cast extra sets?
Here is what the readings should be using 3.55 gears in the rear end with the 4.11 speedometer gears in the transmission. These are with P225/75R15 tires:
Reads Actual
25 29
30 35
35 41
40 46
45 52
50 58
55 64
60 70
65 75
70 81
75 87
80 93
85 98
Correction factor is 1.1577464788732394366197183098592
The 235/3 speed combo with 3.55 gears will cruise all day long across Kansas at 85 actual, but gas mileage suffers!
Last edited by chevy50jim; 10/16/12 11:02 AM.
|
|
|
|
|
Joined: Nov 2002
Posts: 7,472 Likes: 26
ChatMaster - 7,000
|
|
ChatMaster - 7,000
Joined: Nov 2002
Posts: 7,472 Likes: 26 |
Would you happen to also know the correction facton if using the 373 gears?.
Steve D
|
|
|
|
|
Joined: Nov 2002
Posts: 7,472 Likes: 26
ChatMaster - 7,000
|
|
ChatMaster - 7,000
Joined: Nov 2002
Posts: 7,472 Likes: 26 |
I have to agree with Gene because using the correction chart above you would have to be going 100 mph to be 15 mph off. The GPS check would be the best place to start. Also when you say your cable is "oiled" what exactly are you using for lube?
Steve D
|
|
|
|
|
Joined: Jan 2008
Posts: 366 Likes: 1
Backyard Mechanic
|
|
Backyard Mechanic
Joined: Jan 2008
Posts: 366 Likes: 1 |
Steve6
It is 1.10187
Just divide 4.11 by 3.73
Dean 50 - VCCA #44675
|
|
|
|
|
Joined: Nov 2002
Posts: 7,472 Likes: 26
ChatMaster - 7,000
|
|
ChatMaster - 7,000
Joined: Nov 2002
Posts: 7,472 Likes: 26 |
Thanks Dean-I'll be doing the swap in the future and this info will be helpful. The 4:11's are great in the hills but I would like to be able to travel the highway with a little less engine whine.
Steve D
|
|
|
|
|
