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#1
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3.42 First gear Super T-10 in a track car
We are building a more dedicated autocross/road course car and the transmission I have is Iron case (904) and steel midplate Super T-10. The downside is the dreaded first gear. I am trying to figure out if it will stay together (at least for awhile!) for what we are doing considering it probably won't see first gear, especially on a road course. Are these transmissions weaker just because of hard launches with sticky tires out of first gear? Does this make the rest of the gears weaker somehow as well?
Will be in a 3200 Ibs 77 T/A with at least 500hp of Pontiac power. Appreciate the input! Colin
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1970 Trans Am, numbers matching, White, Auto, A/C, Owned since I was 15. 1973 Trans Am, numbers matching, Brewster Green, Saddle interior...Sold :-( 1978 Trans Am 400-4spd, non-numbers matching 400, Low compression daily driver, 9.66@73.5mph 1/8 mile....Sold :-( |
#2
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I think the 3.42 is rated at like 250 lb TQ
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#3
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Hi Tom,
Something low for sure but wondering if that just the case for hard first gear starts and then is it the same strength as any other super t10 for the remaining gears? Sent from my SM-A530W using Tapatalk
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1970 Trans Am, numbers matching, White, Auto, A/C, Owned since I was 15. 1973 Trans Am, numbers matching, Brewster Green, Saddle interior...Sold :-( 1978 Trans Am 400-4spd, non-numbers matching 400, Low compression daily driver, 9.66@73.5mph 1/8 mile....Sold :-( |
#4
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I have been running them for almost 20 years.Had one in a 63 421 HO.Raced it a few times with a 3.42 in the back and never broke it.I think the weak spot will be between the main drive and the cluster.I have one in my 421 62 GP right now.A guy at Richmond told me they have a 20% fudge factor on their ratings.I think a iron case and mid plate will help.Worst that happens is you break it!Tom
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#5
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Quote:
The 3.42 gearset has the lowest torque capacity rating of the available Super T-10 gear sets. The 3.42 main drive gear(gear on end of input shaft) is much smaller in diameter than the gear it is driving on the front of the cluster gear. The strongest arrangement is when the input gear and the gear it drives on the cluster gear are closer to the same diameter. So that means that the closest ratio unit will be the strongest. The 2.43 close ratio gearset is the strongest of the Super T-10 gearsets and is identified by 2 identifying grooves on the input shaft spline. As far as not using 1st gear and avoiding drag race style launches, that will definitely help it live longer. But dont forget; the power flow for the speed gears 1st, 2cnd and 3rd flows through that same weaker maindrive gear and front cluster gear combo. To illustrate, the 2.43 gear set has a 21 tooth maindrive gear driving a 28 tooth gear on the front of the cluster gear, while the 3.42 set has a pitifully small diameter 17 tooth input shaft driving a much larger dia 31 tooth gear on the front of the cluster gear. Power flow for all gears except for 4th flow through the maindrive/cluster gear pair. Curious, where did you get the 904 nodular iron case and is this a 1st design Super T-10 or a 2cnd Design Super T-10....or is it a Richmond (basically a 2cnd design)? From a HotRod online article: " the Super T10 that Pontiac specified for its high-torque 400 and 455s was a close-ratio unit with a First-gear ratio of 2.43:1, which happens to boast of the greatest torque capacity rating of any Super T10. ........... As years progressed, new lower-ratio gear sets were developed, and by 1980, a First-gear ratio of 3.42:1 was used with 301ci Pontiac and 305ci Chevy engines. The number of gear teeth required to achieve that ratio made the gears vulnerable. The above speaks for itself .. wouldn't you say? Here are the available gear-sets as listed by Richmond gear. Last edited by 10secbird; 03-15-2020 at 06:14 PM. |
#6
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I've toasted two late '70's Super T-10's in the '79 T/A with 3:23 rear and drag radials. I contacted Paul Cangelosi of 5speeds.com and had him build a new Autogear aluminum cased, billet mid-plate, all new internals, based on a Muncie M21.
Awesome trans for a fair price.
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Home of WFO Hyperformance Shaker induction. |
#7
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Quote:
The TA will go back to a manual eventually. How much for the Auto Gear, horsepower rating ? |
#8
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I have a t101 going in a project now. Sitting next to a stock t 10 it looks like a heavyweight vs a lightweight. The tailhousing has 5 bolts, the case is way thicker.
It will hold much more horsepower. The shifter set up on that one is great too. |
#9
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Quote:
Paul offers an array of options including gear ratio's. Give him a call or checkout his youtube video's.
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Home of WFO Hyperformance Shaker induction. |
#10
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I think that's the key line in your post - also, at least on a road course you won't be doing a hard start from standstill, although for autocross that may be an issue.
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#11
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Autocross you will be lauching pretty hard at the start and using 1st some tight turns. In the 79 Camaro(with teh IA in it now) I autocrossed a 380 HP 383 with a ST-10 out of an 80 Z28 and 3.73s and 25" roadrace slicks and used 1st often.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#12
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Skip, did you have any issues or did it do okay? Although the car will see some autocross it will only be to shake down the car as we are setting it up mostly for road course duty. Was also thinking I could just start in second for the autocross work, it will have more then enough torque anyways :-)
As far as the autogear stuff it's definitely nice stuff and might happen down the road but we are trying to keep costs reasonable with this project and it's kind of a use what we have type of thing, All this came about as we have been taking our cars to more and more track days and one of our friends wrote off his old car, he was okay but just by luck. So we decided to build a dedicated track car with a proper cage, fire system etc, life is too short already!
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1970 Trans Am, numbers matching, White, Auto, A/C, Owned since I was 15. 1973 Trans Am, numbers matching, Brewster Green, Saddle interior...Sold :-( 1978 Trans Am 400-4spd, non-numbers matching 400, Low compression daily driver, 9.66@73.5mph 1/8 mile....Sold :-( |
#13
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Fingers crossed, my 3.42 1st gear Super T-10 has lived with the 406 on my 81 T/A for both drag racing and autocross. I've only used street tires on it and have kept more pressure in the tires as a safety precaution. I do have a much stouter iron case T-10 1B (over the counter performance tranny) that will be going in the car sooner than later.
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Johnny US Army Retired 1978 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 |
#14
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The iron case helps big time. The reason they are weak it the 3.42 gear is so small. Heavy car and sticky tires in an aluminum case has a short lifespan. The case spreads/ flex's and the gear shears. The iron case will not flex, this helps a bunch. Just take it easy on the launch.
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#15
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Here's a ratio chart for the B/W T-10 if anybody needs one.
http://www.dandltransmission.com/borgratio.html
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Johnny US Army Retired 1978 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 |
#16
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Two years of running the 455 T400 T/As was extremely successful with both cars. I was class winner (C/Prepared) for the year with my 73. I took 4 first places, 1 second and a third and wound up with the trophy for the winner of the class that year. I also ran a borrowed T/A 6.6 400 77 Bandit car one time with a 4 speed, and saw no advantage over the T400 cars. The owner wanted someone to drive the car that had experience autocrossing, and asked me to drive it. I've owned a good many 4 speed Pontiacs and never saw any advantage to using a manual transmission on a dirt track, or an autocross course, won a good number of events using a slushbox. Both of the dirt cars in my signature pic have T400s, 67 GTO has a 400 engine, and the 69 GP had a 428 in it, zero transmission problems with either car over a 5 year period 13 feature wins, and a good many heat race wins over 5 years................ |
#17
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autos= boring
3 pedals= mucho fun |
#18
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3 pedals, much more room for operator error, broken driveline parts much more frequently, missed gears, jammed shifters, been there done that, not my idea of fun. If you want to win, you have to have all the advantages in your favor.
2 pedals, almost no room for operator error, and dead consistent, never break a transmission or clutch, no shifter to jam, much easier to be able to judiciously modulate power to the wheels, (spinning ain't winning, in any form of motorsports). If winning races is boring, I'll take boring every time. I've tried it both ways, and would never go back to a stick because of the need for consistency and reliability. This isn't drag racing the OP is talking about, it's closed circuit racing, totally different animal than running for 10 seconds in a straight line. You have to ask yourself, why Jim Hall, one of the most successful engineers, innovators, and builders of the Chaparral sports cars, used a T400 in his road race cars, and was super consistent, won scores of races with his cars. Hard to argue with the success Jim Hall had using a T400 in his race cars for years. I drove semi for 7 years, I've probably shifted a stick more times than many people on here. There is no pleasure from rowing gears for me whatsoever, in a race, street car, or a truck. It's monotonous, and there is no reason to subject myself to it. When I was young, everything I owned had to be a stick shift, as I got older, and more experienced, nothing I owned had a stick shift in it. I do curently own an IH wrecker that has a 5 speed in it, if I could have gotten a truck with an Allison in it, for what I paid for the 5 speed truck, I would have bought a truck with an Allison. |
#19
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__________________
1970 Trans Am, numbers matching, White, Auto, A/C, Owned since I was 15. 1973 Trans Am, numbers matching, Brewster Green, Saddle interior...Sold :-( 1978 Trans Am 400-4spd, non-numbers matching 400, Low compression daily driver, 9.66@73.5mph 1/8 mile....Sold :-( |
#20
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I have had 6 daily driven manual transmission vehicles. Never had to replace one clutch. My work beater is at 240K with original clutch and exhaust. Many times simple is better. But not better for car companies pocket books. |
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