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#1
12-11-2023, 02:02 PM
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Low 1st Gear TH-400
I know some people put a lower 1st gear in a TH-400 to get out of the hole faster. I understand how this would improve 60' times. Now with the lower 1st gear when you shift into 2nd you will have a larger RPM drop than you would with the standard 1st gear. Can someone explain how this will affect overall E.T.? Would the 1-2 shift pull the engine down and cancel out any gain in 60'?
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Tim Corcoran |
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#2
12-11-2023, 02:11 PM
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I had a lower 1st gear in a TH400 the late Greg Merrick built. It was great while it lasted...BUT that planetary gearset (I believe from a TH200) is much weaker. My HFT cammed 463 did this to it.
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 Johnny US Army Retired1978 T/A 463 Pontiac, KRE 74cc 292CFM D-ports, Lunati VooDoo, V-max lifters, TKII, ATM 850 E85 carb, TCI TH-350 race tranny, 3600 converter 3.73 12 bolt 11.63@116.68mph 1981 T/A 4-speed 406 Pontiac, Merrick ported 6X heads, Comp 270S cam, Crosswind intake 750 Street Demon, 3.42 30 spline Eaton posi street car. 1980 Formula 350 Pontiac back burner project 1972 LeMans 350 Pontiac |
| The Following User Says Thank You to Johnny406 For This Useful Post: | ||
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#3
12-11-2023, 03:49 PM
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depends on HP and converter.
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#4
12-11-2023, 07:57 PM
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Non-stock 1st ratio is a Waste of money with 400+ CID, if ya gotta upshift before the 60foot
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#5
12-11-2023, 10:49 PM
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I dont have numbers in front of me and sometimes varies by manufacturer but i believe second gear is also lower.spreading out the RPM drops its not just on 1-2 shift
Also i believe the higher quality units have 5 planet gears, Hughes stands out in my memory as a better one
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A man who falls for everything stands for nothing. |
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#6
12-11-2023, 11:05 PM
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When first gear is lower your second is also in my th400 and the pinions are square cut. Its makes alittle noise but not really noticed.
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#7
12-20-2023, 11:23 AM
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Coan offers many different gear ratios for the T400
Rossler offers many different gear ratios for the T400 and also the 4L80E Scott McClay offers many different gear ratios for the TH200 Stan
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Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
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#8
12-21-2023, 09:35 AM
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I used a coan in my grandville years ago it was 5 pinion gear set and very strong! Those Tci ones are junk and weak, not sure what greg used above
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Darby 74 Grandville 2Dr 455 c.i 4550# 2011 1.60 60 ft,7.33@94.55-11.502@117.74  2017, 74 firebird -3600 lbs (all bests) 1.33 60 ft, 6.314@108.39 9.950@134.32 M/T 275/60 ET SS Drag Radial 2023,(Pontiac 505) 1.27 60 ft, 5.97@112.86, 9.48@139.31.... 275/60 Radial Pro's |
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#9
12-30-2023, 01:36 PM
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Hey Tim,
Learned of these gear sets in the early 1980s and first used one on 72 GTO street/strip car. My first 11 second daily driver back then in 1985. I liked it and swore by them for 10 years or so but, as time went on, I now think it good for a heavy street car owner than does not want to use an OD trans. Otherwise, probably best not to use one on a dedicated bracket deal. Have one today in a trans I purchased with a car. Not sure what I will use it in, maybe one of my station wagons.
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Hundreds of Pontiacs in Az "Real Pontiacs only..no corporate nonsense!" Facebook- Pontiac Heaven Hosting- 23rd annual Pontiac Heaven weekend- Phoenix pending due to covid Pontiac Heaven Museum in process Phil 2:11 Last edited by Steve Barcak; 12-30-2023 at 01:43 PM. |
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