[STEELCITYFIREBIRD]

What does it take drive train and chassis wise to stand up behind the 455-469" torque monsters being commonly built?
Tranny, rear axle assembly,etc?
Unibody cars, what mods are mandatory?
Traction?

I'm contemplating a stroked 400, for the future, trying to put a rough $ # together of everything needed to make it viable and useable.

......I have a feeling I'm going to drop or greatly scale down the plan for the future!

[tom s]

For street driven cars with stock type tires really nothing more than stock stuff.Remember the factory put them together to live on the street,trans,axles drive shafts etc were built with a percentage that they could take before breaking.I have been very lucky over the last 55 years with only breaking stuff at the track.My 421s made HP in the 500 plus range always with stick shift running gear.Broke axles,trans and drive shafts on the strip.BUT,kick the HP up 50% and put on big sticky tires bad things can start to happen.Your use will dictate what you will need.You will get lots of opinions and recommendations.Tom

[b-man]

TH400 trans with your choice of performance converter.

Ford 9" rear with aftermarket axles and locker.

Custom driveshaft.

275/60-15 drag radials, one set every year.

Subframe connectors welded in if unibody.

Have fun all the time with no worrying about parts failure.

Pay the money once, do it right.

[ponyakr]

I can only say what my experience was. When I switched from a 400 to a 455, I broke the TH400 intermediate sprag(2), The outer sprag race in a TH350(2), a built Glide, an 8.2 BOP rear, and rotated the center section of an 8.5 rear on the axle tubes, sending the pinion up thru the floor.

Solved the TH400 problem with a 34 element sprag. They can now be built to be practically bulletproof.

Never tried another TH350. But nowadays, they can be built to take a lot of torque, using a heavy duty 36 element sprag/drum/race package, + other mods.

Glides can be built to withstand 2000hp or more.

For the rear end, I'd go straight to a 9" Ford or Dana 60. The base, bolt in 9" will start at somewhere around $2000, depending on what level you want it. There are all sorts of HD options available. You can save a few bucks, if you can come up with your own chunk, on the cheap.

http://www.quickperformance.com/QP-G...ge_p_4017.html

http://www.quickperformance.com/Brake-Kits_c_61.html

http://www.quickperformance.com/Comp...ons_c_558.html

http://www.ebay.com/itm/FORD-9-INCH-...hUoCeM&vxp=mtr

http://www.strangeengineering.net/pr...embly-nb.html/

A complete D60 can go for well over $3000, as can the 9".

http://www.moserengineering.com/comp...pack-dana.html

http://americanpowertrain.com/i-2091...-trans-am.html

http://www.moserengineering.com/comp...uscle-pak.html

A new heavy duty driveshaft with the big 1350 joints on each end, with matching HD slip & pinion yokes, will handle a pretty healthy Pontiac.

http://www.pstds.com/shop/drag-shaft...m-steel-shaft/

A unibody will definitely need welded in frame connectors. A full cage, with bars to the front frame rails will help hold everything together.

As mentioned, all the trashing of parts happens when you go to sticky tires. If there is a weak link, a big torque Pontiac engine will find it.

[Steve C.]

Similar to B-man except I have a 12-bolt rear and using aftermarket axles. My rear end has always been a Auburn differential. It's been handling 580 to 600+ hp with no issues. Only changed to a spool on a limited street 700 hp level.


.

[Tom Vaught]

Experience just says that you have broken a lot of parts!

If you never put a tire on the car and get it to hook you will rarely, as TOM S said, break anything on the street.

If you get it to hook, at first you break driveline parts, then you start hurting the body sheet metal. Ever look at a early GTO with a vertical 'crease' above the rear tire openings? You are killing the sheetmetal if you see that. Body is twisting.

So if it is a race car, tie the thing together with a proper cage structure.

If it is a street car (not a "Street Outlaw" car driven on the street), then there are some things that will help. Don't even bother if it doesn't have a roof on it. Then a custom cage is the only way to really do anything with the car (if you have a tire).

Tom V.

[92GTA]

What I've learned with my 461...

TH400 (had a TransGo kit installed in my original).
I have a 12" 3200rpm stall converter.
New Auburn posi for my original 3.23 peg leg.
245/60-14 fit the Rally II wheels great.
Hotchkis subframe connectors, welded and using solid body mounts.
CalTracs Traction bars (I'm running old school ones now tho until I can afford them).

I know better than to ever try to run drag radials or I will blow my original 8.2" rear and I know at some point my TH400 will need the upgraded sprag and a freshen up.

All that said, the amount of TQ is just a joke on the street, it's like a comedy skit. Traction is still practically non-existent.

If you are serious, you will get an upgraded rear, I plan on one from QuickPerformance some day when I can afford it. Then you can run street slicks and not worry about something breaking.

[Steve C.]

Forgot to add.... I also use CalTracs Traction bars. My subframe connectors are welded in as recommended. And when I used a TH400 it was well built.


.

[STEELCITYFIREBIRD]

I listening and digesting, keep it coming...I'm hungry for knowledge and other's experience!

[Cliff R]

You really woln't have any problems until you take steps to find good traction.

The big 455's hit the drive train pretty hard and can easily spin any rear tire that you will try to use, even DOT's.

At the track you will be able to get them to hook, then the weak links in the drive train will become an issue.

I've never broken anything behind any of my engines on the street simply because the tires slip some.

At the track I've broke just about EVERYTHING behind the engine, which has required upgrading all of those parts to effectively handle the power.

The weakest link in the deal will be the drive shaft and U-joints, and the factory 10 bolt carriers. The later 8.5's are tougher than the early 8.2's, but I still blew those carriers to bits on hard launches, requiring an Eaton unit. At the same time I upgraded to Mosier axles, and absolutely and for sure weld the axle tubes to the center section.

I use a custom built driveshaft with 1350 Brute Force joints, and aftermarket slip yoke and 1350 yoke for the 8.5 ten bolt diff.

Trans is a TH400 with all the good stuff, and I've still broke the 34 element sprag once.

Since the Ventura is uni-body I added sub frame connectors and welded them in place.

Since all the upgrades I've logged over 1000 runs w/o issue, other than the one transmission sprag started to slip so I just replaced the entire transmission.

Been using a Continental 10" converter the entire time and it's been flawless. They are NLA, so not sure what I would go to if I ever broke it?......Cliff

[Half-Inch Stud]

I got this.

Trap-Locked Driver Motor Mount
Electrical cooling fan ( no mechanical fan if you can manage it, like i manage it)
TH400 built properly, 34 element sprag, Full direct pack circuit.)
ATI 10" 2800-3200 converter or similar.
Denny's 1350 driveshaft with 1350 TH400 yoke.
Rear: Ford 9", Dana60, Anything tougher than a stock 12-bolt.

A-body: the tie bars from lower-to-upper links.
F-body: Subframe connectors that bolt-in & can be welded later., J-bolt slapper bars or the new thingy dingy.

9.5-10.0 compression for Street pump gas. I went too low with 9.0:1

get-er-done

[ponyakr]

"...Trans is a TH400 with all the good stuff, and I've still broke the 34 element sprag once..."

I've never broke one. That's probably because I've never made much, if any, over 500ft lbs of torque. But I know a BBC guy who broke several of those, before switching to a Glide.

They now have 36 element sprags, Ultra Bells, complete HD cases, and other upgrades to withstand some BIG power. I think some of the Pro Mods are using these now.

http://www.ckperformance.com/View/4L...-ELEMENT-SPRAG

https://jet.com/product/detail/f092f...a:2&code=PLA15

http://www.jegs.com/i/ATI/085/400013/10002/-1

http://www.reidracing.biz/transmissi...ases/sh400drag

http://www.coanracing.com/Catalog.as...uctDetail=1565

http://www.atiracing.com/products/trans/400/

http://www.rosslertrans.com/products.html

http://www.jakesperformance.com/th400/

http://transmission-specialties.com/...x.php?cPath=32

http://www.mikestransmission.com/cat...e400trans.html

[68blackbird]

So what should I do to my 12 bolt 3:73 factory posi. It's bone stock with about 5000 miles in the rebuild.

[Cliff R]

To clarify the 34 element sprag didn't break or roll over, it just started slipping on the races under full power. Doesn't much matter as it still required replacement.....Cliff

[ponjohn]

Old combo - 532 ft lbs at 3200.

Drag radials on the street were useless even with Caltracs.
Ran a 12 bolt with a spool, 33 spline moser axles.

Dynamic T400, 4L80 is another good choice.

Subframe connectors and an 8 point bar.

[STEELCITYFIREBIRD]

"absolutely and for sure weld the axle tubes to the center section."

Is this a weak link on my production 76 rear axle, regardless of big power?

[Chicagogoat]

A street/strip 12 bolt needs upgraded 33 spline C-clip eliminator axles, 1/2" wheel studs, and a good Auburn or Eaton posi. I've recently tried the Tru-trac for a short time and haven't ran at the track with them yet but I will say they hook hard on the street. Can't cheap out on the rear or the rest of the drivetrain, need a built 3" .080 wall chrome moly tubing driveshaft, 1350 spicer u joints and chrome moly yokes, safety loop (I prefer one that attaches to the trans mount), trans & converter built by those who know make them live at this level. It is advisable to have the tubes welded to the housing for those heavy hard launching cars. Also good insurance to get a deep alum pan and a good external cooler to keep your auto trans and converter from deep frying. 455+ with good flowing heads will survive for years with said equipment.

[Steve C.]

Leaf springs ? What are we running today ?

Many years ago when we contacted John Calvert with his Caltracs traction bars for a heavy F-body inconjunction with lots of torque he was suggesting the Landrum Spring Company. At that time the hot ticket was a heavy 300 lbs/in rate leaf spring. For us it worked for a 1.47 60-ft time with a M/T ET Drag 28.0/10.5-15W tire. Back then at a 3800+ lb race weight.

Now today the trend seems to be a 'lighter rate' spring. And the split-mono leaf spring is popular. And some here with Mopar springs.


.

[Half-Inch Stud]

Originally Posted by Chicagogoat

A street/strip 12 bolt needs upgraded 33 spline C-clip eliminator axles, 1/2" wheel studs, and a good Auburn or Eaton posi........

Losing my edge, need to switch to caffinated. How did i forget to mention the wheel studs.

[ponyakr]

Originally Posted by 68blackbird

So what should I do to my 12 bolt 3:73 factory posi. It's bone stock with about 5000 miles in the rebuild.

I ran a stock axle 12-bolt with a mini-spool & 3.73 gears in my '69 GTO. Cast rod 455/#62 heads, 041/Rhoads, 750 Q-jet, TH400, stock converter. It only ran mid 12's, with 60ft times in the upper 1.60's. So, it didn't really hit the rear end that hard. But, at that power level I never had any problems with the 12-bolt, at all. I did put longer studs in the axles. But they were 7/16", not 1/2".

Also ran a '68 Bird with a similar 455/TH400/stock converter. It had a 12-bolt with stock axles, factory posi, & 355 gears. Ran low to mid 12's. No problems.

Ran a '71 Bird with similar engine/trans/converter. It also had a stock axle 12-bolt with a mini-spool & 4.88 gears. It ran a 9.85 on a 1000ft track. No rear end problems.

Didn't have C-clip elims or 1/2" studs on any of these rears. BUT, I did add 4 small tack welds to each axle tube.

I've read that most C-clip elims will eventually leak, with continued street use--some worse than others. SO, if I was going to set up a street/strip car, and my budget permitted, I'd go to a 9", a D60, or at the very least, a correctly built 8.5 with bolt-in axles. Of course, aftermarket 12-bolt housings are available with bolt-in axles.

http://www.moserengineering.com/comp...e-package.html

http://www.strangeengineering.net/pr...g-mounts.html/