|11-14-2012 04:04 PM|
|cobalt327||Check rear gear ratio|
|11-14-2012 08:26 AM|
With the 2004R Trans the Driveshaft doesn't have to be cut if the TH350 has a 6" Tailhousing but, the Crossmember does need to be move back about 5-11/16".
Automatic Transmission Identification
|11-14-2012 08:26 AM|
cheaper gear change...
what rear r u running now ??? and do u know the gear ratio also. if not jack up the rear, mark the d-shaft and tire and then rotate the tire counting the turns on the shaft.. u'll be close without pulling the rear apart.. if your in the 4's then move to a higher gear (lower number) in the low 3's...
|11-14-2012 08:04 AM|
|big gear head||
I'm assuming that you mean a 4 speed automatic overdrive transmission. A 4 speed manual would not help you. There are several overdrive automatics to choose from. The 700R4 has a 3.06 first gear which wold be about useless with a 4.xx rear end gear ratio. The 200 $r would be a better choice because it has a normal first gear and a better overdrive ratio, plus it's the same length as the TH350 and the cross member doesn't have to be moved.
If you do go to an overdrive transmission you will need to get a good drive shaft. I would recommend at least a 3 1/2 inch tube to beat deflection at high drive shaft RPMs. Otherwise you are going to get a vibration somewhere around 60 MPH or higher.
|11-14-2012 07:31 AM|
The way you sit now, with a 30" diameter tire (middle of the road size) your rear ratio works out to be about 4.25:1.
With a .7 OD the effective rear ratio becomes about 3:1 and at 65 mph the engine drops to just over 2000 rpm. This is a hard to beat combo IMHO.
You can play with these calculators to see what you can come up with: Wallace Racing - Automotive Calculators.
|11-14-2012 07:02 AM|
what size tires on the rear.. so we can get the height in inches .. to figure out your reargear...
and what rear is under the truck.. the stocker.. or a later one?
|11-14-2012 06:15 AM|
|Paul E Cain||
Rear end questions
Recently purchased a 1941 Ford with a chevy 350 and automatic 3 speed transmission. @ 65 miles per hour Tack reads 3,100. Should I change to a four speed transmission, or can a different differential be installed. Looking to better fuel millage. Engine is a high performance Edelbrook.