Rear end or tires?
Thread Starter
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Junior User
Joined: Jun 2010
Posts: 65
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From: Jackson, TN
Rear end or tires?
So I think I have finally figured out the dillema with my C6. I apparently have the 3.55 rear and decided to get her up to 70 MPH with the newly acquired sunpro tach from the junkyard ($8 special).
SO at 70MPH, I am running right at 3000RPM. Given my gearing and recent discovery of gear calculators online, I am assuming my 3rd gear is working. I just don't see practicality in driving at 70MPH while at 3KRPM.
1) Can put 32" tires on it and drop that RPM down to 2600 or so?
2) Is it more practical (or reliable rather) to drive at 2600RPM?
3) Will the 302 handle the 3000 RPM cruising? I drive interstate everyday.
4) Is a 3.08 rear an option?
5) Say screw it and drop in an E4OD?
I really appreciate the patience guys...one day I will have this thing finished and will owe you all a ton!
SO at 70MPH, I am running right at 3000RPM. Given my gearing and recent discovery of gear calculators online, I am assuming my 3rd gear is working. I just don't see practicality in driving at 70MPH while at 3KRPM.
1) Can put 32" tires on it and drop that RPM down to 2600 or so?
2) Is it more practical (or reliable rather) to drive at 2600RPM?
3) Will the 302 handle the 3000 RPM cruising? I drive interstate everyday.
4) Is a 3.08 rear an option?
5) Say screw it and drop in an E4OD?
I really appreciate the patience guys...one day I will have this thing finished and will owe you all a ton!
Laughing Gas
Joined: Feb 2010
Posts: 781
Likes: 8
From: Sanford, NC
70 MPH is about right with 3.55 gears. Larger tires will drop the RPMs some but you
would have to correct the speedometer if you put them on. You could change the
rear end to a 3.08 or a 2.75 and better crusing RPMs. The E4OD or an AOD trans
would help the situation but might be hard to get right in your situation.
would have to correct the speedometer if you put them on. You could change the
rear end to a 3.08 or a 2.75 and better crusing RPMs. The E4OD or an AOD trans
would help the situation but might be hard to get right in your situation.
Thread Starter
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Junior User
Joined: Jun 2010
Posts: 65
Likes: 0
From: Jackson, TN
70 MPH is about right with 3.55 gears. Larger tires will drop the RPMs some but you
would have to correct the speedometer if you put them on. You could change the
rear end to a 3.08 or a 2.75 and better crusing RPMs. The E4OD or an AOD trans
would help the situation but might be hard to get right in your situation.
would have to correct the speedometer if you put them on. You could change the
rear end to a 3.08 or a 2.75 and better crusing RPMs. The E4OD or an AOD trans
would help the situation but might be hard to get right in your situation.
Senior User
Joined: Sep 2009
Posts: 459
Likes: 0
Changing rear end gears or tire size will require a speedometer gear change.
Thread Starter
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Junior User
Joined: Jun 2010
Posts: 65
Likes: 0
From: Jackson, TN
I'm taking this thing to a trans shop Tuesday. One minute I drive it and feel like it is doing fine. The next it throws me a curve. If I put it in 2 and drive, it never shifts. If I throw it in to D after that, it shifts hard. If I move from D to 2 it never changes.
Moderator
Joined: Jan 2001
Posts: 57,028
Likes: 2,764
From: Virginia
If your road speed is too high, the tranny is programmed not to let you downshift into 2nd and blow the engine up or damage the drivetrain.
You had better leave your 3.55 gear in that truck with the 302, or you will never be able to tow or haul anything. The 302 needs rpms to make power. I would not go bigger than a 31 inch OD tire.
Thread Starter
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Junior User
Joined: Jun 2010
Posts: 65
Likes: 0
From: Jackson, TN
If you put it in 2, it's not supposed to shift, that's the way Ford designs most of their trannies to work. It starts off in 2nd, and this is good for snow and ice. Then of course it's not going to shift into 3rd because you have it in 2nd.
If your road speed is too high, the tranny is programmed not to let you downshift into 2nd and blow the engine up or damage the drivetrain.
You had better leave your 3.55 gear in that truck with the 302, or you will never be able to tow or haul anything. The 302 needs rpms to make power. I would not go bigger than a 31 inch OD tire.
If your road speed is too high, the tranny is programmed not to let you downshift into 2nd and blow the engine up or damage the drivetrain.
You had better leave your 3.55 gear in that truck with the 302, or you will never be able to tow or haul anything. The 302 needs rpms to make power. I would not go bigger than a 31 inch OD tire.
Is the 302 sturdy enough to take 3000 RPM on the highway?
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Moderator
Joined: Nov 2007
Posts: 22,415
Likes: 92
From: Denver Metro Area, CO
Franklin is spot on with his explanation of the tranny's operation.
Sure, but I would say to hold at 60 or so.
Sure, but I would say to hold at 60 or so.
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Thread Starter
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Junior User
Joined: Jun 2010
Posts: 65
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From: Jackson, TN
I'll put 31's on it and run it an even 70 up I-40. That should help.
Thanks!
Moderator
Joined: Aug 2002
Posts: 6,111
Likes: 386
From: Southern California
So I think I have finally figured out the dillema with my C6. I apparently have the 3.55 rear and decided to get her up to 70 MPH with the newly acquired sunpro tach from the junkyard ($8 special).
SO at 70MPH, I am running right at 3000RPM. Given my gearing and recent discovery of gear calculators online, I am assuming my 3rd gear is working. I just don't see practicality in driving at 70MPH while at 3KRPM.
1) Can put 32" tires on it and drop that RPM down to 2600 or so?
2) Is it more practical (or reliable rather) to drive at 2600RPM?
3) Will the 302 handle the 3000 RPM cruising? I drive interstate everyday.
4) Is a 3.08 rear an option?
5) Say screw it and drop in an E4OD?
I really appreciate the patience guys...one day I will have this thing finished and will owe you all a ton!
SO at 70MPH, I am running right at 3000RPM. Given my gearing and recent discovery of gear calculators online, I am assuming my 3rd gear is working. I just don't see practicality in driving at 70MPH while at 3KRPM.
1) Can put 32" tires on it and drop that RPM down to 2600 or so?
2) Is it more practical (or reliable rather) to drive at 2600RPM?
3) Will the 302 handle the 3000 RPM cruising? I drive interstate everyday.
4) Is a 3.08 rear an option?
5) Say screw it and drop in an E4OD?
I really appreciate the patience guys...one day I will have this thing finished and will owe you all a ton!