Got a 700R4

Topic: Got a 700R4

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Posted: 5/18/10 1:50pm Message 11 of 19

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KDADDY79

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Dutchess County, NY - USA

Joined: 8/27/2007

Posts: 2484

Vette(s): White '79 Corvette. It's a driver.

Yeah, even though the exhaust is more of an issue than I thought, I'm still glad I got the 700R4. "Ce la vie."

I think anyone considering this swap should consider the possibility of new exhaust when they are adding up the costs.

Larry at Corvette Specialties is sending me the pipes and mufflers I need. I oughta be cruising at low RPM's soon enough.

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Got a 700R4

Posted: 5/19/10 7:21pm Message 12 of 19

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wetvet

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Lake Oswego, OR - USA

Joined: 10/17/2003

Posts: 559

Vette(s): 1972 Steel Cities Gray T Top. Original Owner, Original Paint and Interior. The running gear has been rebuilt. only 250,000 miles on the clock..

What rear end gear are you running with the 700R4? I've always considered this trans change for my Vette. I have 3.08's with the Turbo 400. 3,000 rpm at 70 mph. What is the new rpm at 70 mph with the new 700R4?

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"It Takes A Little Longer To Do It Right"
"It Takes A Lot Longer To Do It Again"

Got a 700R4

Posted: 5/19/10 8:32pm Message 13 of 19

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2tonevette1981

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Hillsboro, TX - USA

Joined: 3/2/2008

Posts: 148

Vette(s): 1981 beige/bronze

With mine I kept the stock rear end and as far as the gearing in the tranny you would have to ask Joel. He rebuilt it. At 70 mph I run 1900 rpm

Got a 700R4

Posted: 5/20/10 5:58am Message 14 of 19

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KDADDY79

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Dutchess County, NY - USA

Joined: 8/27/2007

Posts: 2484

Vette(s): White '79 Corvette. It's a driver.

Mine has (stock) 3.55's. The correct speedo gear hasn't been installed yet so I can't say what RPM's at what speeds.

In the meantime I have driven it at hwy. speeds and it's real obvious how much less the motor is working once it clicks into OD.

Got a 700R4

Posted: 5/23/10 6:28am Message 15 of 19

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Autom8r

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Old Hickory, TN - USA

Joined: 5/26/2003

Posts: 599

Vette(s): 1978 L-82 Silver Anniversary hotrod. /////////////

Get a speedo gear for a C4 with the 3:43 diff. With your larger diameter tires it reads just right in your 3:55 diff.

Dave

Got a 700R4

Posted: 5/23/10 7:44pm Message 16 of 19

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KDADDY79

Former Member

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Dutchess County, NY - USA

Joined: 8/27/2007

Posts: 2484

Vette(s): White '79 Corvette. It's a driver.

Dave,

That's good info. to have.

I've been out of town for a couple of days and the speedo gear is on my "to do" list for this week. Thanks!

Kevin

Got a 700R4

Posted: 5/24/10 6:15am Message 17 of 19

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lukesvette

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HOWELL, NJ - USA

Joined: 5/18/2004

Posts: 6812

Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.

Kevin,

Here's a useful site that provides the different gear combos based on rear end gearing. There's also a calculator to verify based on your tire size.

http://www.transmissioncenter.net/speedometer_calibration_______va.htm

Confirm which drive gear is in your tailshaft before ordering a driven gear. My driven gear is actually right but my drive gear is actually wayyyyyy off - should be 15 tooth and theres a 9 tooth gear in there - looks like its out of a TH350...