How fast have you gone on 8 inch rear?

I know our rear ends are typically not the strongest especially for drag racing. I am on the look out for a 9 inch to build, but was wondering how fast have you all gone on the 8 inch? So far I am at 12.48, but my car leaves very soft. I just have 4.11s with a mini spool. Factory axles and all.

 

I've been 11.98@117, but was on street tires and very soft launch (2.30 60' not flooring til 2nd gear). The general consensus on the interwebs is 400rwhp through an auto on sticky tires.

 

6.30s @ 111mph 1.40 60 in the 1/8 mile

 

12.77 until I hit it with the Transbrake, 8 go Boom then.

 

7.11 @ 97mph with 1.49 60ft
With a toploader behind a 347

 

11.43 with a 1.53 60' , stock axles, 4.62 gear and a mini spool

 

7.19 at 93 in the 1/8 with a 1.49 60ft. Stock axles with a spool and 4.11 gears

 

Do you think the 8in can hold more power with a spool vs the factory diff? Or is it just a combo of everything being sized small?

 

this is just my opinion, I believe a spool is stronger since there is less stuff to break. The 8 inch is a small rearend but in a light weight car off the foot brake it can last a while. As long as it doesn't get a sudden impact like releasing a trans brake or dumping a clutch it should be ok within reason. I have been a 1.49 60ft on one spraying off the line and plan to go faster this year. Its not an apples to apples comparison but I ran a stock 10 bolt in my 02 z28 to a 1.42 60ft and probably 100 passes from 1.4-1.7 60fts before it broke and those rears are notorious for breaking

 

I ran a...Powertrax...with trans brake (C-4 and AOD) on slicks with my 8". I now have a Detroit locker using foot brake, same 8".

a vid in my garage on how fast I've been on my 8". first vid is my 16 yo Son at the track (trans brake).
...

 

Been mid 6's on a mini-spooled 8". The pinion is a weak link. Broke a couple of them. And obviously putting a spool into an 8" won't solve the pinion problem.

Do they even make a spool for an 8"? I've run mini-spools but never saw a full spool for an 8"?

The 9" is a LOT stronger, even a stock case 9" with a spool has got to be twice as strong as an 8"? Only problem I've had out of a 9" is breaking the pinion support bearing area (tail bearing). Currently have an aftermarket case and so far so good.

Off topic, but there was another forum where I see reference to a guy switching from a 4.11 9" to a 4.10 8.8 and picked up .15 second in the 1/4 mile. I don't believe it myself.

 

Thanks for the info. I've seen a few spools for the 8in. I'm putting a 8.8 in mine, I'm running 3.73's for now until I need more gear.

 

Lots of good info here. I've found even with good parts (solid pinion spacer, using a locker or doing up a 4 pinion traction loc, etc.) the 8" rears have their limitations! There weak points are either the pinion gear itself or the smaller case caps! Auto trans cars can run some good numbers with them but used behind a manual trans. or higher stall converter in a car that has some pretty good HP the 8" in time will either snap the pinion gear or a cap will let go after awhile. I noticed even going from a 8" to a 9" with same gear ratio, car will slow a little in the 60' due to driving larger gears and a little added weight. A 8.8 will use less HP to drive a car over the 9" design. That's why Ford dropped the 9" in f-150's for 8.8's years back looking for less rotating HP requirements for fuel mileage.

 

Forgot to mention above, 8" your limited to the small u-joints also!

 

One advantage to a 9in. is that it is the only rear that has 3 pinyon teeth always on the ring gear,that is why it takes more power to pull it.