Drivetrain questions. Maybe rebuild TH350?

1980Esprit

1980Esprit

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Alright, first thing to start it off.

We own 1980 Trans am as I am sure most of you know by now, and that we are putting in a 406.

Motor consists of .30 block, .10 mains/rods, Eagle H-beams, KB hyper flat top (6CC valve reliefs), Moly rings, stock crank, clevite bearings, melling oil pump, fel pro gaskets, edelbrock performer RPM, rebuilt Q-jet carb, rebuilt pontiac 350 heads, comp cam 262 XE, true dual roller timing chain, mechanical carter pump, heddman LT ceramic coated headers, new valve springs-retainers-keepers to use with new cam, hardened push rods, comp magnum roller tip rockers, ARP head bolts.

We think it will be right around 350-375 HP, 450 TRQ
Car is expected to reach peak torque at 2K, peak HP at around 4.5K-5K


*TH350*
-What torque converter stall/brand to use?
-What rear gears would be best? Has 3.08 LS right now.
-How much for a shop to build motor to specs to handle power?
-How much for me to buy a rebuild kit/shift kit and get it done myself? I would get it done at school because I currently have a transmission class, and the teacher has years of experience.
-What would I need to do with the rear end to handle the extra power from stock?
-Any suspension mods required?
-What gauges would you install in the vehicle to make sure everything is good? (ie: Transmission temp, oil temperature, fuel/air ratio.. etc.. ?)

Thanks for now, Rylen.
 
Trans also has a bad leak, would this be eliminated by a rebuild?

In the picture you can see the ATF, of course along with coolant.
 

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Only thing I am left wondering is what kit/ or kits would I need to be able to handle that power? I am unfamiliar with transmissions right now, and not sure which kits to buy/ and what brands to look for.

What type of kit would work?

Also for the rear end. Is that stock 10 bolt fine? I am just wondering because I hear all of these horrid stories of blowing out the rear end. I guess it will be a street car, but will have some `fun` sometimes with it!

I was just wondering about a rough estimate for a shop to do it. $500, $1000, $1500...?

-Rylen
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For what it's worth I would look into an overdrive transmission. There are parts that can make it stronger than what you need. Sunshell, servos and a shift kit. The stock 10 bolt will be fine on street tires.
 
I was thinking 200r4 but I just dont have the funds to buy a new transmission. If I were to do a trans swap later down the line it would be a T-10.

Alright so say I am looking for a kit; what are ALL the parts the kit needs to come with. I have heard about a B&M kit on summitracing, but heard people say that it does not come with some of the things needed to do a complete build. (I have a basic idea of some of the things in an auto trans. Still learning and have lots to learn about the rest.)

http://www.summitracing.com/int/parts/bmm-30229/overview/make/pontiac
 
It is impossilbe to tell you all the parts you need until the transmission is disassembled and all the components checked for wear or damage. The shop costs depend upon what you are asking them to do, machine shop work, engine assembly, engine installation, hourly rates of the shop, etc.
 
A Turbo 350 will last behind anything if its built right. The TH 400 is pretty much bulletproof stock.

I had a Turbo 350 built for $700 with convertor and it lasted behind my 425 Cadillac in outside temp 115* racing heat with no tranny cooler.( still in the car today untouched )

Give your best tranny shop in town ( ask around whos the best ;) ) your specs combo and they will build it for you. Or buy one from Jegs or Summit.

On a budget , just get a shift kit and a good trans fluid to make it last longer. ( extra cooler too if you have a stall convertor)

Doug in P.R.:cool:
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All today I was thinking more and more about that 200r4. I would really like an OD because of those taller gears. I think we cruise at 2.1K (Not sure, long time since summer was here LOL) with th350, 3.08, and 225/70/15.
Really considering that OD trans, Dad will phone up the shop in the city and ask them about prices for th350 and 200r4.

If they were expensive we were maybe just going to build the th350 at school. Heard that 200`s were much more difficult.

Any ideas if 200r4 would cost more than th350 just in general? I know shop to shop will be different.

-Also, what RPM would we be hitting with a 200r4, 3.55s, and 295/50/15 tires?
 
Way back in my youth, my best buddy was building a 63 Chevy II to run 10s in the quarter mile. His tranny was a TH400 with a full B&M rebuild. I can't tell you if the kit had everything he needed but I can tell you that if it was bullet proof when stock, then it was bomb proof after the rebuild!

If your leak is not the result of a crack in the housing and you elect to keep the TH350 I think you will be happy with a B&M rebuild. I'm sure B&M will help you determine every thing you might need if you contact their customer service. Of course, if you have a good tranny shop in town, I'm sure they will be happy to work with you on getting the results you are looking for.
 
Local shop said it would be $1000 for the th350 rebuild for 450 hp/trq. Said that they can`t warranty the trans because of the power level. It is a reputable shop in the area though. They said they wouldn`t build a 200-4r and to stay away from them, and 700r4`s were even worse.

What options am I left with? Really want an OD. Most of the car shows are long highway drives and dont want to be spending all of the budget into mileage, and revving like a mother going down the highway. I know these cars wont get much mileage but an OD will help. Car with the turbo 301, 3.08s right now gets around 10 mpg. All stock. With the new motor we are hoping for a couple more mpg.
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Find a shop that isn't stuck in the "80's. GM overdrive transmissions can be built right by someone that knows them. I have a 700r4 that stands up to 450 - 500 hp. Contact Dana at Probuilt, or Bowtie overdrives.
 
My options are fairly limited. The shop is 45 mins away in the city and no others in there. Other choices for shops are 3.5 hours away. Not wanting to travel that far for a transmission rebuild though. I knew that I had seen that when BUILT they can handle some decent power.

May have to buy a new transmission then?
 
This shop had also recommended a 2400 stall. They had done this, WITHOUT us telling them our camshaft specs, gears, etc.. They based the stall off of our HP rating. I know that the cam used stock converter. (Whats the difference between different stalls anyway? Little confused about it)
 
Well dad had got talking to the shop and they said to stay away from 200r4, and the 700r4 was worse. Dad got talking to a person at his work and that guy had said to stay away from them. It bothers me because he said even when build they will blow with that much power. My dad is a little stubborn so he will take there advice ahead of mine. Guess the automatic OD is out of the question. (Unless a gear vendor OD kit), I just do not want the motor I built to fail from access high revving, and also mileage will go down the toilet (I know carbs/classic cars get bad, but this would be terrible).

MYSELF, looking at the richmond 5 speed OD, about the same cost to put in as the auto OD trans (TH350 with Gear V OD).
 
Not sure where you think you will have so much horsepowere that you are going to blow transmissions? A 69 Ram Air II with 10.75 compression and the 068 cam and large valve heads was rated at 366 HP by the factory. You arent installing an 068 cam and you are using small heads with small valves I believe and wont have that much compression.
 
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