[Tom Vaught]

"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.

[Formulajones]

Originally Posted by ponyakr

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/

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.

[Chicagogoat]

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

[MDGOAT69]

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.

[ta man]

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.

[ta man]

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.

[torqhead]

Originally Posted by Half-Inch Stud

A-body: the tie bars from lower-to-upper links.

Can you provide more detail what this is?

[torqhead]

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

[Chicagogoat]

Originally Posted by torqhead

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

I like these

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

[TCSGTO]

Originally Posted by torqhead

Can you provide more detail what this is?

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

[torqhead]

Originally Posted by Chicagogoat

I like these

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

Will either of them work on a 700R4?

[Chicagogoat]

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

[b-man]

Originally Posted by Half-Inch Stud

A-body: the tie bars from lower-to-upper links.

Originally Posted by torqhead

Can you provide more detail what this is?

This.

[69FIREBIRD76MM]

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

[ponyakr]

"... 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.

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. 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.

[Formulajones]

Originally Posted by b-man

This.

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.

[Formulajones]

Originally Posted by 69FIREBIRD76MM

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

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.

[Chicagogoat]

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

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.

[ponyakr]

"...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.

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

[STEELCITYFIREBIRD]

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