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tranny question

 
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TheDocta
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PostPosted: Mon Jan 14, 2008 1:22 pm    Post subject: tranny question Reply with quote

hey guys,

right now i am deciding what to do with my car, i am either going to go with a big block or sell it off and build a foxbody mustang with a SBC and a turbo.

i think i have a turbo 350 tranny but am not entirely sure,

i recently had installed 373 gears at the advice of my mechanic

since then i have had a problem with going on the highway. My car is only able to comfortably do 50 around (2k rpms at the top of high gear) and the highway to the track has a speed limit of 65, being NJ i can not do 50 on the highway for 40 minutes and live to tell about it

so my question is

what would be the best tranny to solve this problem?

automatically 700r4 pops into my head because everyone swaps to that tranny for its overdrive

i am looking for a tranny that is automatic, will give me the least amount of power loss, is relitively cheap and will allow me to do 80 or 90 on the highway comfortbaly

also if known how much should i expect to spend


any and all input is appreciated


Thanks guys
-TheDocta
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jonny_b
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Joined: 28 May 2003
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1979 Chevrolet Camaro

PostPosted: Mon Jan 14, 2008 3:07 pm    Post subject: Reply with quote

First off, why can you only do 2,000 rpm in high gear at 50 mph? why not drive at 70mph and 2,800 rpm. I use to have a 4-speed manual in my camaro with 3.73 and I ran 70-75 at around 3000rpm.

But anyway, unless you NEED the very low 1st gear of a 700r4 (I think its around 3.06) you should really look for a 200r4, that way you have a more normal 2.70ish 1st gear and I think it has a higher overdirve.

You'll have to wait for another response from someone whos knows more about prices, but I think they are about the same. I'm a manual tranny guy, I like shifting, so I have little knowledge about auto's.

How is the tranny being used? What kind of power are you putting through it? Nitros?

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1979 Camaro Z28
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TheDocta
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PostPosted: Mon Jan 14, 2008 3:19 pm    Post subject: Reply with quote

if i go up to 3500k rpm it only make like a 6mph difference in my top gear

currently i would guess around 400hp is going thru it (rounding up), i have a wieand 177 blower on a 355 with a 650cfm carb

but if i keep the car i will be looking to make 700hp + hopefully down the line
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clay
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PostPosted: Mon Jan 14, 2008 6:46 pm    Post subject: Reply with quote

If you have a TH350, the 200R4 is a cheaper swap. It is the same length and the same driveshaft / yolk setup will work. It will live fine behind 400 - 500 h.p., however, 700+ is basically out of the question for the 200R4 unless you spend an astronimical amount of money. If you are going to go the turbo route, it will probably take even less gear. From what I gather, they need to be loaded hard to build exhaust heat. 86GN can elaborate more on that than I can - he has first hand experience. At 700+ honest horsepower, there isn't really going to be a cheap overdrive solution. I think some of the 700R4's are living behind some pretty decent power, but I personally wouldn't trust them at this level. 4L80E with a seperate contoller or something like a TH400 with GearVendors are the only two things I would consider living with no problem at that level. I run the latter and absolutely love it. Adding 1500 rpm to your cruise speed and only picking up 6 mph doesn't add up though - strange, converter slippage maybe....Clay
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TheDocta
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PostPosted: Mon Jan 14, 2008 9:23 pm    Post subject: Reply with quote

clay wrote:
If you have a TH350, the 200R4 is a cheaper swap. It is the same length and the same driveshaft / yolk setup will work. It will live fine behind 400 - 500 h.p., however, 700+ is basically out of the question for the 200R4 unless you spend an astronimical amount of money. If you are going to go the turbo route, it will probably take even less gear. From what I gather, they need to be loaded hard to build exhaust heat. 86GN can elaborate more on that than I can - he has first hand experience. At 700+ honest horsepower, there isn't really going to be a cheap overdrive solution. I think some of the 700R4's are living behind some pretty decent power, but I personally wouldn't trust them at this level. 4L80E with a seperate contoller or something like a TH400 with GearVendors are the only two things I would consider living with no problem at that level. I run the latter and absolutely love it. Adding 1500 rpm to your cruise speed and only picking up 6 mph doesn't add up though - strange, converter slippage maybe....Clay


does a th400 have a overdrive?

and im guessing i would need a new driveshaft

is that correct?
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af2
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PostPosted: Mon Jan 14, 2008 9:53 pm    Post subject: Reply with quote

The TH400 is a 1:1 deal. The 200 would be a good choice as Clay pointed out.
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TheDocta
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PostPosted: Mon Jan 14, 2008 11:22 pm    Post subject: Reply with quote

af2 wrote:
The TH400 is a 1:1 deal. The 200 would be a good choice as Clay pointed out.


so they th400 does not have an overdrive

do you think that the 200 would be able to handle 700 hp and launches at like 4k rpm?
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jeep_406
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PostPosted: Mon Jan 14, 2008 11:29 pm    Post subject: Reply with quote

The 400 with an overdrive would be a 4L80. If you have your heart set on 700 horsepower I thing a 3 speed turbo 400 with a gear venders overdrive is the only way to go. With a gear venders setup, a redone 400 and a good converter I'd think your going to be paying in the area of 4 grand maybe a little more depending on the converter.
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10sec.et
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PostPosted: Mon Jan 14, 2008 11:38 pm    Post subject: Reply with quote

TheDocta wrote:
do you think that the 200 would be able to handle 700 hp and launches at like 4k rpm?



Clay wrote:
It will live fine behind 400 - 500 h.p., however, 700+ is basically out of the question for the 200R4 unless you spend an astronimical amount of money.



as stated, the TH400 is NOT an O/D but you can add the Gear Vendors unit to it .........http://www.gearvendors.com/hrgm3s.html

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clay
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PostPosted: Tue Jan 15, 2008 5:39 am    Post subject: Reply with quote

Quote:
do you think that the 200 would be able to handle 700 hp and launches at like 4k rpm?

Cheaply - absolutely not. This one can though.
http://gearstar.net/transmissions/details.php?unid=76
Check out the price though - $5995.00 (plus $75 charge for synthetic oil - you think they could at least give you that). Anyway, you can do either the 4L80E or the TH400 / GearVendors thing for about 1/2 that (ballpark figure). Clay
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TheDocta
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PostPosted: Tue Jan 15, 2008 9:52 am    Post subject: Reply with quote

clay wrote:
Quote:
do you think that the 200 would be able to handle 700 hp and launches at like 4k rpm?

Cheaply - absolutely not. This one can though.
http://gearstar.net/transmissions/details.php?unid=76
Check out the price though - $5995.00 (plus $75 charge for synthetic oil - you think they could at least give you that). Anyway, you can do either the 4L80E or the TH400 / GearVendors thing for about 1/2 that (ballpark figure). Clay


so really i should be looking to buy a th400 with gear vendors overdrive and if that doesnt work try for a 4l80E
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clay
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PostPosted: Tue Jan 15, 2008 6:16 pm    Post subject: Reply with quote

If you don't care about having an automatic - automatic, there may be a cheaper solution. I'm pretty sure Transgo has a way to run a 4L80E in full manual mode with basically valve body modifications - no seperate controller. This would probably be the cheapest way for a tough overdrive - not the most user friendly though. Keep in mind another cost thing - converters will be more expensive for the 4L80E than a TH400. Clay
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Knarley Darley
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PostPosted: Wed Jan 16, 2008 2:46 am    Post subject: Reply with quote

If you are really going to make 700 Hp screw the expense and just change the rear gears to 3.08s and build a t-400 trans. Then overdrive will not be needed and you will make more power than you can hook anyway even with the tall gears.
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TRANS03
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PostPosted: Wed Jan 16, 2008 8:50 pm    Post subject: Reply with quote

What kind of car is this (or approx. how heavy is it), what converter are you using, and what rpm are you spinning the engine up to?
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