OK Guys -- let's open up a can of worms. I'm not looking for opinion but rather fact: Which rear end is the strongest (can sustain hard street miles and launch a 3800 lb car at the strip) and have the best chances of survival? The GM 12 bolt The GM 10 bolt The Dana The Ford 9" Other? And lets be real locker rear ends belong on the strip only cars. I would actual like to be able to make a tight right hand turn and NOT have the rear of the car skid around the corner. I'm not buying one tomorrow but I have long term (read that as retirement plans) to build a very stout A Body (1970/71 GS or Skylark) with a 455 (or 462 or 464) that will do a planned 11.5 +/- in the quarter (J Weise Level 2A). So, which rear end will give me the best service? Last the longest? Take the most abuse and keep on ticking? I don't think this question matters if I have a 4 speed or auto, what the gear ratio is or the size of tires. After all the torque gets past all that stuff, which rear end will be standing at the end of the longest day? Craig
Honestly, I think you could get all of thoughs choices to work. I would say the the 10-bolt is the weakest of the three but could certainly stand up if built right. I'd go with the 12-bolt since it's readly availible, HD parts are easy to come by and it's common enough that lots of people have experience building them. You can even get an after market 12-bolt houseing now. Just my opinion, I'm sure others will share thiers.
Muscles If we're talking "JUST" all out strongest on ONLY what you've listed I'll say Dana 60. Close tie on the 9 / 12 and then the 10 bolt. Everything has it's weak link and differentials can be built stronger if need be. But that's a conversation i'd catagorize by specific differential build only. Now driveshafts on the other hand.........(insert can-o-worms) :grin: :laugh: Let me know when you want into that discussion! :TU:
I've heard the the Dana is the strongest rearend. But I'd bet that the Ferd and the 12-bolt can all be built to withstand all but an all out funny car.
Craig , Believe it or not these things do matter. A 12 bolt is a strong rear but that is a function of the size of the ring (dia) and also the location of the pinion in relation. That is why there are now 12 bolt style drop ins for 9 inch ford housings for cars like mine. This works well in lighter cars and gives a performance advantage. The dana is the strogest but by far the heaviest and the least gear selection as you go up the scale in ratios ( not a problem in a buick) Stay away from any 10 bolt. Not that it cant be made strong ---but why? The problem with all the rears are the housings. They tend to flex and deflect and eventualy will toe the rear wheels in. A 30 year old housing is just that -- an old piece that has seen service life and then you are trying to keep it from doing bad things. Any way you go over build it. A manual hits everything harder.The proof of that is the different chassis setting that you use in manual vs automatic. When I built the 12 bolt for my car we put both new ends and TUBES in the center. Even stock tubes need to be welded all the way around, spot welds ground and rewelded.Mine also has billet caps and a mark williams cover ( same as the TA cover)Mark Williams also has brand new 12 bolts available -- stronger but heavier. If I had to do it again I would do a bolt in style 9 inch such as the type offered by Chassisworks . It is all new with no factory parts. It has a backbrace installed. A converted 9 inch is just made from sheetmetal-- that will bend . One without a backbrace will not be as strong . Plus with the ford it is so easy to change ratios. Hope this helps George in DC
I think it does matter. The "shock" that travels through the driveline is certainly more significant with a four speed car or launching a car with a trans brake. I think footbraking an automatic car contributes to longevity. Make the choice that's right for you, in terms of money, time and fabrication required, but for what it's worth - my car is a 8.5" ring gear ten bolt that I have been racing for 27 years. Currently goes 10.50s at 3850 lbs. I do have Mark Williams axles and a full spool (so I am cheating by your definition). :Brow: But again, I think footbraking the automatic goes a long way towards softening the initial hit. K
Because in my case it's what came in the car. Plus, it's kind of fun running a 10 bolt when everybody else is running a 12 bolt/Dana/9"/etc. :laugh: I have given this topic considerable thought, but have pretty much decided that if I have a failure I'm going to put another 10 bolt back in and run it another 27 years... K
Absolutely--- I know guys who have been running ten bolts forever too. I break just about everything I touch ( broken anvils and all) so I went with the strongest stuff I could put in it. Have fun George in DC
Love these uhhh r/e "discussions"... All comes down to Different needs for different folks. No one r/e is the best choice for every application. Dana 60... my usual answer is WHY in a 10-11-12 sec car... Big, heavy, PITA to set-up. Won't easily fit in a GM A-body. Yeah, if one has one, & the car is gutted, & one is going ladderbars, it's an alternative p Ferd 9"... it's just a 10 bolt p. At a minimum, nodular case, in a heavy A-body going into the mid 11's with slicks. 12 bolt... real good factory ones... oh they're common :grin: The few '69 COPO Chevelles got 'em. Also some quality 12 bolt pieces were put behind factory 455 Pontiac A bodys, & even some pegleg versions in some '70 350 Skylarks. The typical Chevelle SS-Monte-Elco 12 bolt r/e had the weaker metalurgy axles, & vast majority of factory 12 bolt Eaton posis had the poor side gear spider gear combo... shatter & Kaboom. Want a 12 bolt that's really tough, gotta have it built with upgraded parts. Properly built carrier & aftermarket axles... Considering the expense to install bolt-in tapered bearing axles, most would be better off with a properly built 8.5 ten bolt. 10 bolts... have built every version of 10 bolt made. Hundreds of them. Very unfair to lump them in all together. Huge difference in torque capacity across the lines. The very best, IMHO, are the 8.5 bolt-in axle '71-72 units with tapered axle bearings. Not fond of the Warner-Motive posis that went in most '71 8.5's, but will take a rebuilt factory clutch type posi 8.5 A-body rear over most stock 12 bolt posi carriers for strength. Want to upgrade, can go 30 spline with Eaton posi, or 33 spline with spool. Back to work :3gears: Roger
rears of course ya got to think how large and heavy the dana 60 is. as with all the mentioned rears, weight , size and amount of horsepower to opperate needs to be considered . as the 9" has an offset center where rear sway bars can be an issue . and 12 bolts and chevy 10 bolts have them damn c-clips .
....just as an FYI - after breaking 2x stock 10-bolt posi's I had a 12-bolt built with HD Eaton Posi and Moser Axles.....refurbed and strengthened case.....everything new and gone over - $1600 Also bear in mind that with a 12-bolt, new Ring and Pinion gears are NOT available inbetween the 3.08 and 3.42 ratio's from any vendor. I went with the 3.08 since mine is a true street car that see's ALOT more highway miles (at 75 MPH) than :3gears: 1/4 mile passes where best ET is everything.
rear ends Every rear wears and is vulnerable. It is up to the user to keep the parts in tip top shape. There are always unseen problems like manufacture defect and it is mostly human error of assemble that makes any machine and or set-up go bad. How well you put it together and check your tolerances will help down the road. Bigger does have its advantages as far as strength and longevity on heat and stress. I like the pick-' what you can afford and that fits your particular needs.' The spyder gears are the weak link in the posis and pretty much any differential. That is why the power trax and lock right work for those weekend warrior type. The tire should not bark around the corners if the unit is installed correctly. Even posis will chatter and bark (grabbing and slipping)in the corners if the proper level of gm fluid additive is not keep correct. Sounds like you want everything... as you know in this world you can not. Every performace part picked will have an equal oppisite reaction some where else down the road. Example- I want to launch great but yet cruise on the freeway at normal speeds. answer:Well get an overdrive tranny... can they take as much punishment as an all out 3 speed 400th ??? Ok well I will put 3.08 gear in and build a huge monster torque engine... The car will have such bad manners on the street and suck so much gas you wont be able to take it on the freeway ...lol. This is what I mean. you have to make compromises that suite you. I think that is why we see alot of little turbo charged cars right now ... Not to say I go that way, but just look at them - light , powerful handling, gas mileage ??? It just a sign of the times. It is only money so choose you weapons and have fun. If it blows, I guess you have to move to the next one...lol Personally I would go with the 12 bolt chevy they have biggest carrier bearings on the gm models , it bolts right in - no mods there and plenty of upgradable parts in the after market. That's it from me. Good luck on your choice and what ever you pick , I hope it holds up well. Jim PICK A GOOD BUILDER MOST OF ALL!!!
