What's it take to contain/use the power of 455"+ Pontiacs
 

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!

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

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.

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. :eek:

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.

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.


.

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.

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.

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.


.

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

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

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

"...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

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

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

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.

"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?

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.

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.


.

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

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/

"Bolt In" Axles like a Pontiac or Ford has will keep the rear tire from trying to escape and tearing up your rear quarter sheet metal at the minimum or causing a bad crash at the maximum. The Moser Axles are extremely hard to cut on a lathe but I wanted the minimum heat going into the axles so a slow lubricated cutting bit was used. Took forever but I learned how tough the steel and heat-treat/temper process was on the axles. No AD for Moser, just the truth.

I have seen a lot of factory chevy axles shafts over the years (more than 10) with the tire and wheel/axle protruding out of the vehicle. Brakes don't work good on that side when the drum for the shoes is 12" away.

That being said, 10 out of millions built, maybe a low number, but I was the only one counting too. If I see something happen 3 times, the deal is trying to tell me something. Question is: AM I WILLING TO LISTEN?

Tom V.

We have one vehicle here we've run C-clip eliminators in the 12 bolt for about 15 years now, no leaks. Primarily street driven with maybe 2-3 track outings a year. We settled on Strange C-clip eliminator and axle setup. First Moser was tried and it leaked almost immediately. Never a problem since the switch to Strange.

I'm much like you with rearends. I've run basically stock chevy 12 bolts with excellent success with very heavy 4,000 lbs. cars that have run close to the 10 second barrier. One in particular the 12 bolt doesn't have anything more than a Moroso Brute strength posi, and a set of non taper heavy duty Moser 30 spline axles that still use C-clips. No fancy welded axle tubes, no stud girdle support brace cover or any of that stuff. I built that rear back in 1988, countless drag strip passes, 4100 lbs. race weight, 1.5 60 foot times, and at least 30,000 street miles. I never have to touch it.

My father is still running a chevy 12 bolt in his 69 goat. We built that with Strange C-clip eliminator axles setup, still 30 spline, and rebuilt the original GM posi unit with a little more preload on the clutches. That's it. Nothing fancy, no stud girdle, no extra welding anywhere. It's been in the car like that for about 20 years. It's had 4 different incarnations of 455's in front of it and pulls nice wheelies with 1.5 short times. It's a heavy 3900 lbs. car as well and has seen tons of track time. Now he has a 571 in front of it making 760 ft lbs. of torque. I'll admit he is a little sketchy of the rear now but I'm a little more relaxed about it. (I worry more about the stock driveshaft) It hooks extremely well on the street (that car always worked good no matter the surface) and several hits with it now he is getting a little more comfortable with it. Eventually a 9" is going in the car with a better driveshaft and 1350 joints, but I really don't sweat a stock 12 bolt with an axle upgrade, (too much :)) Given this power level now it has me thinking about it, lol.


These cars with automatics in them are really pretty easy on parts, and that's what these examples are that I'm giving. Unless you're running a transbrake I don't worry too much. These cars also are still running their original bone stock driveshafts too, and I would suspect they will break long before any of those 12 bolts give up. I worry more about the driveshafts than anything else, but they keep going (I run good joints and driveshaft loops of course)
It's the stick cars you really have to pay more attention to. On my stick cars here I tend to go a little more overboard with rearend and driveshaft requirements if I plan to hammer the car at the track at all.
My opinion, in a street driven car that might see the track 1 or 2 times a year with an automatic behind it, a basically stock GM 12 bolt, maybe an axle upgrade, and that's all you need. You don't have to spend a ton of money. A setup like that has been reliable for me to bottom 11's in 4,000 lbs. cars. Lighten the car up, say a 1st or 2nd gen firebird, and the stress becomes much less, hence even easier on parts. Just my experiences.

A well upgraded 12 bolt is capable of living a long and reliable life in a street machine type car not a tube chassis race car. Not sure why people think they need a heavier rear like a 9" or Dana 60 with the massive 9.5" ring gear. That's overkill and over budget as far as I'm concerned.

Failures like snapped wheel studs and broken gears on a 10 bolt, even the preferred 8.5" corporate rear are a common occurrence on heavy street cars running well into the 12's. But while breaking an axle or a spun axle tube are less common they do happen at the track, I've seen it before. So that's why I've built my rear that way and have helped a couple friends do the same. The spun axle tube thing seems to happen to leaf spring cars way more often than 4-link. This is possibly due to the extra torsion the tube sees versus a 4-link. I didn't have the tubes welded on my rear, but I would if I had to do it again just to cover all bases.

Around here Strange is our go to place for anything rear end related. Nice to just order and pick up heavy durable parts without the high price of shipping :usa2::cool:

This is a very interesting read. I haven't decided on an engine for my 69 yet but I have a Chevy 12bolt and a T56 waiting to go behind it. Hopefully that combo can take some abuse.

I've ran a stock 8.5 rearend in each car since I started going to the track in 2000.The current car has a Moser reinforced cover that's it.I've ran stock driveshafts since 2000 also with stock heavy duty u joints.I currently run a Hughes th350..I did hurt a th 350 back in 2009 but driver error may have been the cause.Both cars have CE bolt in frameconnectors but welded at the front.The current car has a driveshaft loop.

Continental 3200 10 inch has been flawless since 2002..I did pay more for extra welding and brazing.

I consider myself very lucky with zero rearend problems other than one bent axle.The rear is being upgraded this spring with either a 30 spline Eaton Posi and new axles and welded tubes or a total replacement.

With an engine approaching 600hp its time to upgrade.Also with the new engine I will be using a SFI Mondello billet steel flexplate.

As for traction good luck with no suspension work or tires.My car actually does well on the street for traction with reduced front weight,15x4 Welds,Skinny M/T sportsman,and 275/60/15 et pros rear.Just cheap CE 3 ways 90/10 and 50/50 shocks I've had it dead hook on the street and from about 20mph it hooks and goes.

Can you provide more detail what this is?

What's recommended for an A body for driveshaft loops, any particular manufacturer?

I like these

http://butlerperformance.com/search....riveshaft+loop

These are prettier but the stock stamped steel ones will suffice
http://www.umiperformance.com/catalo...roducts_id=286

Will either of them work on a 700R4?

Turns out Ram Air Restoration has just 3 loops that fit 350, 400, & 700R4/powerglide/4L80 trans's

When I got mine over 10 years ago it was an Indian Adventures product.

http://www.ramairrestoration.com/dsl...owerglide.html

This.

http://i137.photobucket.com/albums/q...t/DSC02893.jpg

Are those driveshaft safety loops NHRA approved. Will like to run one, anybody here runs one?

"... Not sure why people think they need a heavier rear like a 9" or Dana 60 with the massive 9.5" ring gear. That's overkill and over budget as far as I'm concerned..."


This statement makes me wanna know EXACTLY how much you think it will cost, to completely upgrade a 12-bolt, with bolt in axles(not C-clip elims), enuff to, without a doubt, withstand the abuse which a real healthy long stroke Pontiac can dish out. :confused:

Right off the bat, you'll need aftermarket tubes, with bolt-in axle type ends & matching brakes. Then you'll need a good quality posi & axles, new gears & bearings, and most guys will have to pay somebody to install & weld up the new tubes, as well as set up the posi & gears. Or, just buy the whole thing ready to bolt in, for which I've already posted links showing that a complete 12-bolt costs as much or more than a 9" Ford.

Also, I've read that the Dana 60 actually uses less power than the 9".

https://speedtalk.com/forum/viewtopic.php?f=19&t=28258

Now, if you just wanna try to piece together a cheap factory 12-bolt, with used parts & free labor, because of lack of budget, that's something different all together. I've had to do most of my racing the "poor boy" way. :(

Hey, a cheap homemade 12-bolt MIGHT be all that most will ever need. After buying an 11sec 455 Ventura, & running some 7.30's on our local 1/8 mile track, I discovered that it had an 8.2 rear. And not a BOP 8.2, but a Chevy 8.2. :eek: I figured it had an original type 8.5, or a 12-bolt. Didn't think an 8.2 Chevy was supposed to live at that power level. But it DID !

Hey, there are lots of guys going pretty quick with the tiny 3rd & 4th gen Bird rears.

http://www.bangshift.com/forum/forum...-gm-7-5-handle

http://ls1tech.com/forums/drag-racin...5-10-bolt.html

http://www.hotrod.com/articles/hppp-...rearend-build/

So, this rear end deal is just like a lot of other performance parts. You can always read about SOME guys who have used the weaker parts and never broke 'em or had any problems at all. But, MOST others have not been that lucky.

So, except for the lack of finances, why even take a chance on questionable or borderline strength parts ? I'd say overkill is MUCH better, than taking a chance on all the bad things that a broke rear end can cause.

For a cheaper alternative, Some of your performance oriented A-bodies had a form of this from the factory. My SS chevelle has a factory sheet metal version of these support bars. My fathers 69 Goat never had them, so he sourced a GM set and I installed them recently.

Yes, I run a pair of them on 2 cars, and my father runs one on his GTO. They pass tech no problem. I started making them on my own after the first one I bought. Very easy to make.

My only gripe is that once placed under the trans mount, it can sometimes change the driveline angle to the point that a vibration may become evident. So you have to get creative to correct it. I've sometimes had good luck shaving down the poly trans mounts, or altering the mounting height just a bit. But worth the trouble because I prefer the clean installation of the drive shaft loop without pieces of bar stock running to both sides of the frame, which usually causes other obstructions.

I do realize this is debatable, I'm just stating my opinion. Realize that most people want a GM rear that will fit their GM car with zero mods. All of us on here are gearheads that love doing our own work otherwise who cares just pay the Pro's build your car. You don't need to be an ASE mechanic or have an engineering degree to tinker with your own junk saving money and gaining knowledge at the same time. FYI you can easily fit Strange 33 spline axles with C-cilp elim hubs to fit the small GM housing end to reuse your stock drum brakes. I have pics if the instructions and the mod itself in my archives somewhere. Costs come down to how cheap you can pick one up. The axles with eliminator hubs cost roughly the same as a good posi $450. After that gears & rebuild kit is really all you need to finish it at home. Probably won't save more than $500 doing it yourself versus buying a fully built one for $2500. I scored an A-body 12 bolt core for $50 several years ago :whoo:

As far as the 3 performance rears in question, the 12 bolt is the lightest as far as unsprung weight plus the smallest gears. Small if not slight advantages but worth a mention.

"...I scored an A-body 12 bolt core for $50 several years ago..."


Reckin how much the AVERAGE guy can find a good 12-bolt core for, today ?

I've seen lots of 'em on Ebay for $1500 & more. :eek:

http://www.ebay.com/itm/1970-Camaro-...NXbY5H&vxp=mtr

http://www.ebay.com/itm/66-67-Chevel...9X3pZ4&vxp=mtr

http://www.ebay.com/itm/1970-Firebir...pUY-LN&vxp=mtr

http://www.ebay.com/itm/Chevelle-12-...NYVsEm&vxp=mtr

http://www.ebay.com/itm/1968-72-chev...hYZ0p8&vxp=mtr

http://www.ebay.com/itm/CHEVELLE-12-...VWt8rz&vxp=mtr

http://www.ebay.com/itm/1970-PONTIAC...BX8SbK&vxp=mtr

There are several wide Impala 12-bolts for around $500.

Anyhow, looks like a good core could cost at least $1000, in many areas. Would be much better to go with one of the aftermarket housing/axle packages.

If you go with a factory housing, some say you need the Strange A1033 C-clip Elim kit. It is supposed to be less prone to leaking, under street use, because of using a tapered bearing.

https://www.summitracing.com/parts/str-a1033

Quick changes aren't used much? Status quo on our DLM cars. https://www.franklandracing.com/ And made locally ...to me!

EBay isn't an indication of market value by a long shot! I year ago I was shopping for a 70 endura front bumper that were going for $1000 and one that was listed @$2900 on EBay! I ended up buying one at our biggest Pontiac swap meet for $300 and it was an excellent piece! An A-body 12 bolt can be had for $500-650 or a cool G for an F-body! If you're patient you can find better deals priced to sell @swap meets.

Had a set of repros that were sourced ages ago from the now defunct Frank's Pontiac Parts on my '64 GTO bracket car, they most certainly did the job.

http://i137.photobucket.com/albums/q...rearend002.jpg

Thanks B-man, I didn't even realize those things were being reproduced. My father grabbed an oem set at a local swap meet about a year ago.

The 12 bolt rears and the prices they dictate are really dependent on the axle codes. Collectors and restorers will pay big money for the right one. I have a BX code 69 Camaro 12 bolt sitting here complete that are very pricey now....if you can find another one. I have another 3.07 open 12 bolt sitting here, dime a dozen.

Finding a 12 bolt open carrier 3.07 coded housing is going to be the cheapest bet, then build what you want. I've been down this road, and the issue with that is still cost. A good Eaton is $500, ring and pinion and setup kit is another $300. If you want to stay cheap then using a C-clip non taper axle is stronger than stock, that's another $300 from Moser. Best to change axle bearings and seals while you're at it. This stuff adds up pretty quickly.
So depending on what you paid for the housing to start, you could have anywhere from $1500 to $2,000 in it....IF you set it all up yourself (no labor figured in). And it's still basically a stock 12 bolt.

Just depends on how comfortable you are throwing power at it.

I've also went down the aftermarket route. Strange 12 bolt, Eaton, 33 spline axles with 9" housing ends, stud girdle, 1350 yoke, US Gears, etc.... That set me back $3200 delivered to my door. But you also get larger diameter axle tubes, the cast center section is much beefier than an OEM GM piece with more cast in webbing and larger bearing caps for strength. They also weigh quite a bit more thanks to the extra meat.
So you can beef up an OEM 12 bolt all you want, but they still won't be as robust as the aftermarket units are. I bought one of these for a stick car I was throwing some power at that was fairly violent , and simply didn't want a stock housing under it.
Just trying to help with the price difference a bit so you know what you're getting.
But like I've said, I've thrown more than 600hp/600ft lbs. at what is basically a stock 12 bolt since 1988 in a 4100 lbs. car and it hasn't flinched. Nothing but a Moroso posi and 30 spline non taper C-clip axles. Automatic helps a lot. I don't really worry about it, and tech has never bothered to check for C-clip eliminators :shrug:

LOL, I noticed no one even replied to your question, too many drag racers that know little about a QC rear............:doh:

Most all are spools which is fine for a track car, there are posi units available. Most likely you'd never find a used posi unit. A good QC will suffice to 6-700 HP in a light car so their not the optimum for a drag car. There is also more parasitic loss due to the extra gear set in the back.

If you want a rear axle that requires little to no maintenance, the QC is probably not going to be first choice. The extra noise from the straight cut gears is probably going to be a deal breaker for a street car too.

Being that Frankland is close to you you might call or stop there, and ask their opinions on running their rears on a drag strip.

I saw a 63 Tempest wagon in the pits at Norwalk a few years ago that had a late model QC under it even had the wide 5 wheels on it. I've never seen the car since then. To my knowledge it didn't break during the weekend.

One good thing is, a used unit can usually be had for $500, or less at a circle track swap meet or racing junk.com. The reason is because when circle track racers buy an new car they usually buy it with a new QC in it, making the supply of used units fairly high.

I forgot to add that the much lower placement of the front yoke (companion flange) could cause some problems with driveline angles. A corner type race car is looking for an advantage by lowering the heavy components as low as possible in the chassis, which a QC facilitates, drag cars not so much.

Thanks for all the info on 12 bolt upgrades. Just one part of what may need to be upgraded for a 455 making good street power in the 500hp + range.

My biggest concern is breaking an axle and wrecking the car because of it. I guess losing a driveshaft going through the lights sounds like a bad scenario to haha.

Will the strange c-clip eliminators work with factory axles? Been reading a bunch but couldn't tell.

Thanks
Rich