I'm working on my 1986 Trans Am and i want to swap my current 305sbc to a 383 or a 406 stroker sbc by the end of the summer. Engine power should be around 500+, not sure exactly about how much will be on the rear wheels offcourse.

The car will not be used on the strip, and is only for street use, no burning around or whatever. I however just want more power and a drivetrain that can handle it when i accelerate and use those horses once in a while. I do not need the best gear ratios for the best strip times. If it can handle it without any problem, i would like to keep it the way it is.

Now that being said, i don't want to go cheap and neglect my transmission/drivetrain and i would like some advice about what is most important to replace/rebuilt before doing the engine swap.
My car, which i am talking about:


Budget for drive train incl transmission changes is about 3000 dollar max. I don't want to go much higher and, Keeping the costs less only if i can.

Current transmission a fully stock 700R4, 60K miles driven.
What i would like to know:
Should i go for a full transmission rebuilt? And if yes, any advice on where to buy a nice but complete kit?

Everything els of the drivetrain is stock as it can be.
So can my axle and stock driveshaft handle this? And if not, what should be a propper replacement?

Basically i would like some tips and advice. Any help will be greatly appreciated.

 

I'd have to say you're cutting yourself a little short to build a driveline that is/ will handle 500hp for $3000 unless you can build an engine and transmission. Also, I wouldn't trust a 700R4 to handle that much power.

I'd try to build a Vortec 350 or 355 with about 400hp. I think you'll be happily surprised with a set up like this.

Just my .02.

 

I ment $3000 alone for the drivetrain 'without the engine price included'
Anyway, the 350/355's look nice and a big step up from the stock 305. Its just that the total costs these engines aren't that much lower then something a little bit more powerfull..

Maybe if the stock 700R4 could support a 400hp engine without a full rebuilt, then it would be more interesting. I'm not sure if that is the case though.

 

I'm fairly new to the 700R4 crowd, I've always ran a th350 or th400. I don't know I'd trust a 700R4 to handle much over 400. Also the rear axle won't take too much either.

 

I make about 475 at the crank with my 383. Put a beast sunshell corvette servo and a performance clutch pack rebuild in i . Add a shift kit and never think about Tue transmission again.
PS remote mount torque arm is also something to think about. Get the stress off the trans.

 

A 700R4 can be built to stand up to that OK but it won't be cheap. Talk to the Probuilt guy, he'll set you up with what you need.

 

https://www.700r4l60e.com/

 

500 HP cars are NOT cheap to build.. The chassis, driveline, and suspension will cost you twice, maybe 3 times what the engine does.

The rear end will fail quick and the ONLY good options are aftermarket bolt in housings. Your looking at $2,000 to 3,800 just for a rear end that will hold up (ford 9", chevy 12 bolt, dana 60)

$300-500 for driveshaft and U joints

$1600-2200 for an overdrive trans to handle that power

$450-800 for a torque converter.

Then you need sub frame connectors and at least a welded in 4 or 6 point roll bar (these cars twist alot with 500 HP)

 

I know these guys are right on the money for that build

A Built 10 Bolt ran me $1,530.00 total counting install. =
https://www.thirdgen.org/forums/tran...de-photos.html

Even though a 9in/12Bolt may not be necessary, with street tires if you want to spend the extra money I "would" go with one of them incase you ever change your mind and play at the track with sticky tires.

When my 5.0 finally goes I will be looking for around 350 hp. using the bolt on's I already have. It will be a street car as it is now.

By the way you have a beautiful car.

 

Th700,s are a 6 cylinder gearbox,, low low first gear,, and parts inside made from tin.

 

If you have ever torn down a 1988 - 1993 700R4 you will find that they are quite strong.GM has improved them quite a lot since 1982. The planetaries are much bigger than the TH350 and the TH400. With the right line pressures using the modified TransGo Shift kit (fixes pressure (line rise) and other inherent 700R4 problems) with .500" boost valve, .296" - .300" int/rev boost valve and the right accumulation for quick but not firm part throttle shifts, Corvette servo or Sonnax 2nd apply servo, using 8 or more Borg Warner Hi-Energy 3-4 clutches, Borg Warner Hi-Energy 2-4 band, GM heat treated sun shell, steel re-enforcement sleeve for the input drum, later Borg Warner 29 element input sprag (12.7% wider sprag elements), and possibly "cryo" the output shaft especially with quick 60 foot times or for very aggressive drivers. Always use the Viton input to output shaft seal to guarantee oil to the rear planet. There is not a lot of money needed here, and with the right combination of parts, they can hold over 700FWHP. This is without the billet input shaft or the billet output shaft ($900.00 minimum for both shafts). Keeping the part throttle shifts smooth will increase the durability tremendously. The torque converter must be 10.5" or smaller in diameter to help achieve this durability. There are other little things that will help improve the durability, (too much to mention here) but this is mostly what is needed to make a 700R4 last to some horsepower.

 

Thanks a lot mate. PS that Camaro you got there looks sick!
I may just go for it because i want everything of my car to last.



I can see what you are aiming at, can't have the chassis get weak 'happy its non-rusted at this point' so i don't want it to twist and suffer metal fatigue or lose its shape. I'll have to see if there is any way to get a roll bar in without it looking way off from the original interior. Love the way it looks now. I will weld one together myself if its really needed.



Seems like quite a list of what is needed for the tranny alone. But better do it right then neglect it and break the thing offcourse.

Also thanks to everybody around this forum for the advice.

After reading this, i think it might be better to push the project to early next year so i can save up a few thousand more just to make sure i won't run short on budget near the end of the project. Can't rush something like this.

However i now at least know what i'm going to have to look for. The last thing i want is to install a powerhouse and then having breakdown after breakdown.

 

Don't cut corners with the rear end. I've seen many people spend big bucks on a nice engine, a lot of money on the transmission and then expect the stock rear end to handle it. Most people just don't budget money for a good rear end. It's just as important as the rest of the car.


The 7.5 10 bolt or Borg Warner 9 bolt, which ever your car has, is not up to handling the amount of power that you are talking about. With hard street tires and no high RPM hard shifting it will live a long time on the street, but if the transmission shifts hard or you put sticky tires on it you will likely break it pretty quick. If you have the 10 bolt and break an axle then you may be looking at replacing a quarter panel, if you don't crash and destroy the whole car.


There are many bolt in 9 inch Ford housing and axle packages out there. There are also some nice bolt in 12 bolt rear ends, with Mark Williams probably being the nicest one. Strange Engineering makes a bolt in Dana 60 that is very strong. Look into some of these and then set aside money for something that can handle the power that you want to make.


What is the use of having 500 HP if you can't do anything but smoke the tires? I know that you will want to put some sticky tires on it some time.

 

This is just to show those that don't know why the 9in. is so popular at the 1/4 mile track with big power.
10 Bolt compared to the 9in. gear's .

 

Been a long time since I've seen a 10 bolt apart. That pinion gear difference is huge lol.

 

^^Thats why my street/strip car has a 9" in it^^

 

My wife has a 9" in her now and then... She says it's nice an sturdy

 

I run a 9inch too just didn't realize the pinion gear was so cute in a 7.5 gm.

 

My concern with a 9" would be, I guess they call it "parasitic".
I would think you would need more HP/Torque than a, lets say 5.0 with 200hp to really get that off the line.= rotating mass.
It could even slow the car down.
A price to pay if you want to launce the car with slicks ?

 

The S60 takes something like 13 more hp to turn than the 9"...
And the 9" only takes 3-5 more hp more than a 12 bolt (IIRC)
I better go and find the story in the mag but I was surprised at the 9" being a lot less than I thought.

 

You got that backwards. The 9 inch takes the most power to turn. The 12 bolt and 60 take less power to turn. The 12 bolt is the lightest.

 

I don't think so. I was very surprised by the outcome. S60 was the heaviest and cost the most power in the story I read.

I just read this story and it is backwards from the story I have read before about F-car rearends! (as far as the dana and 9" power loss)

http://www.hotrod.com/how-to/transmi...ear-axle-swap/

 

that story confirmed everything I knew. that hypoid centerpoint robs power but the 9" has that handy pinion support. ill take the 5/5 hp/tq loss for the reliability and lack of c-clips.

 

Just my $.02.

I have been running my 700r4 and stock 9-bolt rear with stock driveshaft for 15 years now. Car made 505 to the wheels on a 175 shot and 365 to the wheels on motor. Car has been run at the 1/8 mile and 1/4 tracks so many times I can't remember. Mostly a street car though. Car runs 11.60 at 117 on motor.

The stock 9-bolt rear had new bearings and 3.70 gear put in back in 2002. 700r4 trans was built by Alan at quarterflash motorsports and I used a 3500 stall yank converter with stock driveshaft. Converter got replaced before the trans and rearend. Trans was $2200 and converter was $700.

Not discounting what these other guys are saying, but I think you will be fine with a properly built 700r4 and a 9bolt rear. I ran et streets at the track each time with a best 60ft on bottle of 1.56 so the rear wasn't getting stressed too hard.

I wouldn't waste money on a 12-bolt or 9 inch ford and th400 with a street car. Break it first, then go from there, no need throwing money away when you don't need to.

 

I've been running my 700R4 for three years now behind a few different engine combo's and so far it's been fine. first was a mostly stock 305, then a 357 with about 320 hp, and now I'm running a new 357 out of a circle track car making 400hp and spinning it to 6500rpm, along with a 100-150 wet shot kit. My 700 is mostly stock other than a Vette servo, B&M shift kit and stall. I also did the 3-4 WOT mod a lot of people on here do. So far no slipping or anything, and I abuse the hell out of the thing daily, including copious burnouts, 4th gear pulls under NX, and 55 mph downshifts to second with 3.70's. (I also run a stock axle 9 bolt).

Not all transmissions are built the same. Some will go at 300hp some have lasted to 650hp or more. Just depends.

Not trying to argue with anyone, Just sharing my personal experience!

 

Thanks for the reply guys.

Sounds like i'm pretty much set if i just mod the good old 700R4 then, i won't be using it on the strips or anything and will use street tires 'I will run 255's for the rear wheels'. So i'm not going to abuse it anyway.

I'm thinking about going for a rebuilt with this kit:
https://www.700r4l60e.com/store/prod...&cat=19&page=1
Along with a nice torque converter. Should be enough then if built propperly.

 

Remember the key phrase here: 'properly built'. I wouldn't let the local trans shop waste time with my tranny, they don't know what they are doing and they only do stock rebuilds. Will they promise it will take more power, yes, will it live in the real world, no.

Get one from pro-built or Alen at quarterflash motorsports. I can vouch for Alen's tranny's, I have run 2 of them.

 

The problem is with buying fully built transmissions from the US for me is the overseas shipping 'anything between 400-600 dollars at least' and import tax '21%' over the entire price. along with some other crap they always pull off to make it cost even more before you get your hands on it.

Same goes for the engine i'll get imported later on. Disguistingly high taxes are disguisting.