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I spent and is spending lots of money on trans and engine. I wanted to go with a strange 12 bolt but not sure it will take the abuse of nitrous. 9in is on the costly side and I dont want a ford on my car if i dont have to. So Dana 60 is up starting at just over 2k is that my best bet? Also the car would see street miles can i get away with a summer of driving with a spool?
No, no, No, NO spool on the streets at all. Not safe, not good, can't turn. I have rode in a few that thought it was a good idea and let me tell you it's not. Can't take corners fast at all, have to turn WIDE like an 18 wheeler would, can break axles easy, wears edges of tires fast, etc.
You need something that will disengage while turning. A locker would work great, or any of the better limited slip units.
I run lockers in mine. When I had the weak stock rear end I used the power trax lock rite and now in my ford 9" I have a detroit locker. The detroit locker is about as strong as the come.
The chevy 12 bolt, dana 60 and ford 9" all has pros and cons. All 3 are strong and well capable of handling 1,000+ hp if built with the right parts. Myself I liked all what the ford rear had to offer so I went that route. I could car less what brand name is on it, as long as it's the best part for my car/usage so it being a ford is not a bad thing to me. In fact its the opposite. Ford 9" has been known as the best/strongest rear ends for hot rods, race cars, etc for well over 40 years.. So it's kinda like a badge of honor to me, to say I have a ford 9" in my car.
For me the ford 9" was the cheapest route to go as well. I bought the moser housing/axle package, then bought a third member elsewhere, and got all my other parts up.. It came out a good bit cheaper than buying a ready to bolt under car rear end.
Ebay (Valley Springs Custom differential) Ford iron case third member with motive 3.89 gear set, used nascar take out detroit locker installed $735 shipped.
Just had to drop the third member in place in housing and bolt it up.
Spohn LCA brackets for 9" rear $98.16 shipped
$18.85 Duralast brake shoes, can of brake cleaner
$5.33, 2 3" U clamps for rear sway bar
$17.72, ES poly rear sway bar bushing
$74.58, ARP carrier studs, 4 qt redline 75W90 gear oil
$45.75, 2 Bendix wheel cyl.
$8.50, 2 dorman U joint u bolt kits
$34, 2 brute force U joints to make up the one rear joint I needed
$17.89, ES poly 2-7/8" sway bar end link set
I used drum brakes, backing plates from a 1978 firebird that I had already.
So $2219 for the ford 9" installed under may car. Not just the price for the unit but all the little nickel and dime things to install it with as you can see from above.
If you was to add up the price for just the rear end as they are sold ready to bolt under, mine would have been under $1900 shipped. The other $300 was the neeed items to install.
12 bolt should hold. Get the 33-35 spline option and truetrac diff or better yet the wavetrac diff for a posi type street setup. Else spool at the track.
I run 12 bolt with truetrac and have 8 second power just havent beable to make a clean pass yet. Its been 5.9's in 1/8 coasting thru after letting off at top of 2nd
87TA on this board has 12 bolt spool i believe and he just went 8.34 at 165 this weekend
Turbo's are softer on launch and I'm using a stage 5 t56 or a rpm modified stock t56 (i got a stock t56 free). I plan on spraying upto 500 shot. 200 from off the line. I dont plan on beating the t56 record just a low 9 will do. I will update my build when its closer to completion.
I guess if you used narrow hard tires, never punched the throttle, drove with a raw un cooked egg in the shell under the throttle pedal it would hold up and last
These stock rear ends can not take that kinda power.. You can add all the best stuff made for it and it still won't last due to the ting ring gear and pinion gear sizes
I think it was SkinnyZ, or Ron USMC that posted the picture of the stock ring and pinion next to a ford 9" ring and pinion... That picture tells it all. Even better than words can.. The stock ring gear is 7.5" or 7.625" the ford 9" is well 9", the chevy 12 bolt is 8.75" IIRC. That may not seem like a lot on paper but side by side you can clearly see the BIG diff in the two and why the tiny 10 bolt can't hold up to that kinda power
Spool on the street? Of course not IF your axle is a weak 7.5, or even an 8.8 with 28-spline 1050 c-clip shafts. But 35-spline 4340 non-c-clip shafts? Go for it. Turning tight? Not difficult if you have enough tire on the front. Just more risk of breaking small shafts.
I installed a few spools in street cars many years ago. Every one of them broke something. 2 of them broke axles, 1 broke all of the studs off of an axle, some broke other stuff. I stopped installing spools in street cars. It's not worth taking a chance on destroying your car or killing someone.
You will all find this hard to believe. You probably all wonder if I swore off hotrodding and joined some weird cult. (My wife would probably prefer that.) But.............wait for it.............I finally installed my QP 9" ford rear end this past weekend. I gave myself the long weekend so I could take my time and in case there were any issues. As it turned out, the install went near perfectly. The only issue I ran into was with the rear u-joint on my aluminum driveline. This the GM performance parts driveline with Spicer u-joints. All my planning and measuring came together great. The one thing I didn't think of was that GM would have used a 1330 yoke on the wimpy 7.5 rear end. Who ever would think such a thing. I ordered the diff with a 1310 yoke thinking for sure the stock rear would use the small u joint. In fact, the rear joint is a 1310 to 1330 conversion joint since the driveline does take a 1310. A new Spicer 1310 joint solved the problem. Other than that, everything went great.
Unfortunately, probably from moving the car out of my garage to the flat bed tow truck and then into the shop, The governor gear in my built 700r4 gave up. I have a new gear coming for Friday so I can get the car on the road this weekend. In conclusion I'll say that the QP is a great option for our cars. Excellent fit. I snapped a few photos.
Oh BTW, that is a Yukon through-bolt aluminum center section with 3.70 gears, Eaton TruTrac posi and 31 spline axles. I ordered the housing and axles with an additional 1/2" on each side to better match rear track to front track. It worked out really well. The housing is QP's light and strong fabricated unit. Something like 10lbs lighter and 30% stronger than factory Ford. It seems like a very nice piece. I was going to get a scale and weigh the stock 7.5 against the 9 to see how much heavier the 9 is. I know it must be a bit heavier. But, I was too busy turned bolts.
Other notes: One of the QP axle housing end options is 93-98 F body (IIRC). I went with this because it should be the same bolt pattern as the 3rd gen and therefore fit the Fly N Bye LS1 rear brake set that I have. The brakes bolted right up. The hard lines that came new with the Fly N Bye kit when I installed it 8 years ago also fit really well. I made a small bracket for the junction block to mount on one of the center section studs.
One thing that concerned me during the install was axle bearing setback. The '02 Z28 brake brackets ala LS1 kit worked well as bearing retainers for the axles, but they install flush to the axle housing ends. I brought the T-bolts and nuts down tight in a gradual cross pattern and torqued them. The axles never bound up. At first they turned hard, but then without oil, the center turned hard. Once I had oil in the unit and wheels on. The wheels turned normally. Therefore, I feel okay with the axle installation. I ran the car in gear on the hoist for a while to run the bearings and gears in a little bit with no load. Then, I started the 5 heat cycle break in, until I was interrupted by the governor gear failure. I'll run through the heat cycle process again after I fix the trans.
One thing I am finding out about the TruTrac is that is is tight in turns. The manufacture literature states that the locker is undetectable until you push the traction envelope. I would say that I agree with that statement. On the street around town, the little bit I got to drive it before I lost all but 1st gear, it was very smooth. Only maneuvering around the shop, tight turns getting into position to pull into a bay, do you feel the rear tires start to bind up. Otherwise, you would never know it's a locker.
All in all, I am STOKED!! To have this bad boy in finally. After it sat against the wall in one of my bays for over a year.
Oh BTW, that is a Yukon through-bolt aluminum center section with 3.70 gears, Eaton TruTrac posi and 31 spline axles. I ordered the housing and axles with an additional 1/2" on each side to better match rear track to front track. It worked out really well. The housing is QP's light and strong fabricated unit. Something like 10lbs lighter and 30% stronger than factory Ford. It seems like a very nice piece.
Very Nice!
Talking about the STOCK Ford 9" Differential... The STOCK Diff. housings broke all the time, when putting power through them.
Way back when new vehicles actually used a Ford 9" or a GM 12-Bolt... It was more common to see a broken Ford Diff than a GM Diff.
The Stock Ford 9" Diff. Housings were really bad... The GM 12-Bolt Carriers/ Ring + Pinion Sets would break often... but NOT as often as the Ford 9" housings.
Today with the HUGE aftermarket support for the 9", 12-Bolt, and Dana-60... all 3 Diffs can handle power and last a long time.
The aftermarket Dana 60 overall is the most robust of the 3... but it also consumes the most power.
The aftermarket Ford 9" is in the middle for strength and power consumption.
The aftermarket 12-Bolt consumes the least power of the 3, but overall is the weakest.
Since all 3 Diffs are available with different carriers and axles (in terms of spline-count and material/ metallurgy) they can all be built from mild to wild... supporting well over 1,000 HP.
Actually the 9" has the largest hypoid offset & therefore consumes the most power of the 3 rears.
The 60 will be the heaviest of the 3 & therefore consumes more power than a 12 bolt.
The pinion offset of the Ford 9" was a decision made after many pinion gear failures in earlier design Ford differentials.
Yes, as you said the 9" shows greater hypoid gear offset compared to the other 2 diffs...
Ford definitely wanted to go in this direction to maintain a larger pinion gear and more tooth contact with the ring gear.
I agree that on paper these qualities should consume more power...
But my in shop testing of the 3 different Diffs (all built to as close as possible, gear ratios, carrier type, spline-count, Etc) has shown on both a chassis dyno and Diff. run-stand/ dyno; for the Dana to consume the most of the 3.
I have no doubt that other people will test and find different results... there are many, many variables... even when trying to build all 3 types of Diffs, to the most similar specs.
I definitely was not able to monitor both the ambient air temp (for the Diff run-stand), and the Diff Oil temp (for the chassis dyno) as much as I would have liked.
For the average street car, 1-2 % is nearly inconsequential... especially if you can have reliability at the cost of a few HP.
I was seeing failures of 12 bolts in the 800+Hp range, seemingly due to pinion deflection & resultant gear failures.
For this reason, I have gravitated towards the S60 over the 12 bolt, due to lower cost & increased gear strength.
Things like back cutting the ring gear for weight reduction, gun drilling axles & lightening axle flanges are all available for a cost that may be worthwhile for the professional racer, but not typically cost effective for the average street/weekend racer.
I feel the same way about driveshafts... I'll stick with the stronger variety (steel over aluminum/carbon fiber etc.) & give up a few HP at the wheels for the assurance they stay connected at both ends.
You will all find this hard to believe. You probably all wonder if I swore off hotrodding and joined some weird cult. (My wife would probably prefer that.) But.............wait for it.............I finally installed my QP 9" ford rear end this past weekend. I gave myself the long weekend so I could take my time and in case there were any issues. As it turned out, the install went near perfectly. The only issue I ran into was with the rear u-joint on my aluminum driveline. This the GM performance parts driveline with Spicer u-joints. All my planning and measuring came together great. The one thing I didn't think of was that GM would have used a 1330 yoke on the wimpy 7.5 rear end. Who ever would think such a thing. I ordered the diff with a 1310 yoke thinking for sure the stock rear would use the small u joint. In fact, the rear joint is a 1310 to 1330 conversion joint since the driveline does take a 1310. A new Spicer 1310 joint solved the problem. Other than that, everything went great.
Unfortunately, probably from moving the car out of my garage to the flat bed tow truck and then into the shop, The governor gear in my built 700r4 gave up. I have a new gear coming for Friday so I can get the car on the road this weekend. In conclusion I'll say that the QP is a great option for our cars. Excellent fit. I snapped a few photos.
I went with 1310 because at my current 400hp power level that will be 450 when the new intake is finished, the small joint is plenty, and it allows me to retain my GM performance parts aluminum driveshaft. I know when I build the new motor at 550hp+, I'll need to do something different with the driveshaft and change the yoke accordingly. The car isn't set up for the drag strip and won't ever see more than maybe drag radials once a year. Therefore I have leaned more towards keeping things light.
10-19-2014, 11:56 PM
