Can't drive at WOT in 4th gear.
02-17-2012, 03:01 PM
#1
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Car: 89 IROC Z28
Engine: 357 TPI
Transmission: 700R4
Axle/Gears: 3.42 Posi
Can't drive at WOT in 4th gear.
Well, the title pretty says it all. When I'm driving say 80-85 and I want to get around a big truck fast. I punch the gas pedal and my car accelerates quickly but before too long in downshifts to third and my tach jumps to 7000 rpm and I am no longer accelerating. Is this because I don't have a corvette servo or something else.
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02-17-2012, 03:10 PM
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Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Re: Can't drive at WOT in 4th gear.
It's by design. You can change the 3-4 upshift valve to delay or eliminate the downshift.
How fast do trucks in your area go that you can't get around them fast at 80-85 mph?
How fast do trucks in your area go that you can't get around them fast at 80-85 mph?
02-17-2012, 09:41 PM
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Car: 1988 camaro z28,1997 camaro lt1
Engine: 355 afr 195 heads,tpis big mouth
Transmission: 700r-4 built by me 3-4 z pack
Axle/Gears: 3.42
Re: Can't drive at WOT in 4th gear.
http://www.bulkpart.com/Merchant2/me...60-700R4sonnax. This is what I have in my iroc will down shift to third and upshift to fourth at fullthrottle.
02-18-2012, 02:18 AM
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Re: Can't drive at WOT in 4th gear.
You can make this modification for about $1.50. You will need two Allen screws and an Allen wrench. And you do not have to drop the valve body. You will be plugging two 4-3 downshift holes in the throttle valve plunger bushing (sleeve). You remove the two bolts that hold the TV bell crank and the roll pin on the valve body. Remove the TV bushing and install the two Allen screws and grind them with a Dremel to make sure that they clear the valve and bore. Reinstall the TV bushing, roll pin and bolts. That's it. Now it will hold 4th at WOT at anything above (Apx.) 65mph. You can make 3-4 WOT shifts also. Give me your email address, and I will send you the instructions on this. Adjust the TV cable to make sure that you have "no play" in the TV cable at WOT when done.
02-19-2012, 11:03 AM
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Car: Base 91 'bird
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Axle/Gears: 9-bolt 3.27 & PBR
Re: Can't drive at WOT in 4th gear.
Is that something that can be added with pics to the tech articles?
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02-19-2012, 03:53 PM
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Car: 83 c10, 2015 silverado
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Re: Can't drive at WOT in 4th gear.
anyone have a part number for a corvette servo on jegs maybe i want to eliminate downshift from 4th at wot this sprig when i do my 400 sbc swap dont know exactly what i need.
02-20-2012, 12:03 AM
#13
Re: Can't drive at WOT in 4th gear.
You can make this modification for about $1.50. You will need two Allen screws and an Allen wrench. And you do not have to drop the valve body. You will be plugging two 4-3 downshift holes in the throttle valve plunger bushing (sleeve). You remove the two bolts that hold the TV bell crank and the roll pin on the valve body. Remove the TV bushing and install the two Allen screws and grind them with a Dremel to make sure that they clear the valve and bore. Reinstall the TV bushing, roll pin and bolts. That's it. Now it will hold 4th at WOT at anything above (Apx.) 65mph. You can make 3-4 WOT shifts also. Give me your email address, and I will send you the instructions on this. Adjust the TV cable to make sure that you have "no play" in the TV cable at WOT when done.
02-21-2012, 05:35 AM
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Re: Can't drive at WOT in 4th gear.
What I suggest will do exactly what the "B&M 70237 - B&M TH-700R4 Throttle Valve Sleeve" does for much much less money.
04-04-2012, 08:00 PM
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Car: 85 iroc
Engine: 383
Transmission: 700r4
Axle/Gears: 3.42
Re: Can't drive at WOT in 4th gear.
You can make this modification for about $1.50. You will need two Allen screws and an Allen wrench. And you do not have to drop the valve body. You will be plugging two 4-3 downshift holes in the throttle valve plunger bushing (sleeve). You remove the two bolts that hold the TV bell crank and the roll pin on the valve body. Remove the TV bushing and install the two Allen screws and grind them with a Dremel to make sure that they clear the valve and bore. Reinstall the TV bushing, roll pin and bolts. That's it. Now it will hold 4th at WOT at anything above (Apx.) 65mph. You can make 3-4 WOT shifts also. Give me your email address, and I will send you the instructions on this. Adjust the TV cable to make sure that you have "no play" in the TV cable at WOT when done.
07-12-2012, 12:10 PM
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Car: 89 caprice
Engine: 350 650 dp on roids
Transmission: 700r
Axle/Gears: 3.73
Re: Can't drive at WOT in 4th gear.
Hi Pro Built.. Im interested in the mods above. Please email me at robbyk85@live.com Thanks for your time.
07-12-2012, 05:15 PM
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Re: Can't drive at WOT in 4th gear.
Joby has a how-to on his site:
www.joby.se/corvette/mods/2002-0X02_tranny_wot/
Dana at ProBuilt plugs the same holes but uses short set screws. Just threads them into the aluminum without tapping the threads first. The set screws make their own threads.
Just be sure that everything moves smoothing afterwards. Otherwise some deburring may be required.
RBob.
www.joby.se/corvette/mods/2002-0X02_tranny_wot/
Dana at ProBuilt plugs the same holes but uses short set screws. Just threads them into the aluminum without tapping the threads first. The set screws make their own threads.
Just be sure that everything moves smoothing afterwards. Otherwise some deburring may be required.
RBob.
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