Best Diff for 600-700hp?

[madmax]

Well, as the car grows more and more out of control, the hp of the engine does too. Im shooting for about 650 at the flywheel, and thats hopefully enough to get me into the 10's. My question is, which differential should I go for? The car is going to be 94% street driven, so I don't really want a Locker, and the next best thing would be a Tru-Trac.

The question on my mind is... if I spring for a D-1SC instead of a P-1SC blower, the engine could put a lot more out than that... so I don't really want a croumpled rear. What do you all recommend?

I've spoken to Currie, Moser, DTS, etc. and they some say that 650hp should be OK, others no...

What about you guys?

Thanks,
Max

[yody]

it really depends on what you are going to do with the car, if you never plan to put slicks on it, or do high rpm clutch dumps, then you can get away with a less beefy rearend. I probably have 630hp or something like that, at least 600 and am only running a 8.5 ten bolt, with 30 spline posi, moser axles and U.S gears with a rearend girdle cover. I don't plan on much drag racing and think this rearend should last a long time. Its also lighter and cheaper than a lot others, there are guys with spools and 8.5's running 9's

[madmax]

it really depends on what you are going to do with the car, if you never plan to put slicks on it, or do high rpm clutch dumps, then you can get away with a less beefy rearend. I probably have 630hp or something like that, at least 600 and am only running a 8.5 ten bolt, with 30 spline posi, moser axles and U.S gears with a rearend girdle cover. I don't plan on much drag racing and think this rearend should last a long time. Its also lighter and cheaper than a lot others, there are guys with spools and 8.5's running 9's

No slicks (well, drag radials :headbang:), no high RPM launches. I will drag race it a bit, but not a lot. Mostly cruising around town. I'm going to be running (probably) a 9" from DTS w/ a nodular strange housing and the likes. DTS uses, amoung others, Strange parts and they are cheaper than the other companies direct. I got a quote in the $2150 area where Moser and Strange wanted $2300-2350. My weak link is going to be my transmission, I would think. I have a local guy who will guarantee (I know that many people here would contest this number) his 700R4 for 700hp for $1200. Can't go wrong with that number (as compared to $4k for a 4L80E).

As for higher hp (than 600-650), I just need it to hold up for a couple dyno pulls if I spring for the D-1SC, because, where the hell am I going to use 800hp on the street :scared:?

Thanks for the imput Yody.

-Max

[yody]

hmmm, 700hp 700R4 tranny for 1200 bucks huh? I would run from that deal as fast as i could, never look back. Don't waste your money. Buy a real tranny NOT a 700r4.

[Nine Ball]

if you will mostly be on radials and running on the streets, a 30-spline alloy axle should be adequate. If you plan on doing any drag racing with hard launches, step it up to a 33-spline axle as a minimum for that hp level.

I snapped one of my factory 12-bolt shafts in the '69 from launching it on slicks. 5500 rpm clutch dumps don't like stock 12-bolt shafts. Upgraded to Moser custom alloy axles and didn't have a problem again (car was approx 600 hp). 12-bolt posi units are just fine for 10-second cars or slower.

[madmax]

Thanks Tony.

The car will be on the streets, slicks probably never. I'll floor it at the strip, but I'm not going to dump it from RPM's.

What differential were you running? I thought once you stepped up to the 33-up spline area you had to use a locker or spool, which is what I'm trying to avoild, as I like to make right hand turns at a stoplight.

-Max