8" Ford will take how much ?

roverman · February 18, 2013, 11:37:10 AM

Stock axles, anybody got torque or hp, they're holding ? I had to trade a hood for this thing, and it's already set-up, for a Jensen Healey. I prefer 5 on 4.5" wheel pattern(options), vs the standard 4 on 4.25" bc. What limited slip, is anybody using, and why. Thanks, roverman.

socorob · February 18, 2013, 01:26:11 PM

I'm using an eaton tru trac 4.10 in mine. Can't remember what it was rated for but much more than my little 6 could ever make.

ex-tyke · February 18, 2013, 05:44:01 PM

Maybe a phonecall/email to Currie or Moser?

flyinlow · February 18, 2013, 06:25:32 PM

I had a stock 8" diff out of a maverick in a pinto wagon that had a really healthy 351 windsor and I hammered on it really hard for several years, i broke allot of stuff but never hurt the 8"diff.

BlownMGB-V8 · February 18, 2013, 07:00:41 PM

Might take Currie's spec with a grain of salt. One time back in 1980 I think they told me one of their 8" axles would handle 1000 hp. Yeah,... maybe for a couple of passes.

Jim

Dan Jones · February 19, 2013, 11:27:45 AM

> Stock axles, anybody got torque or hp, they're holding ?

Some of the drage racers report they will handle up to 400 HP if you
stud the pinion retainer and carrier caps and use premium hardware.

> What limited slip, is anybody using, and why. Thanks, roverman.

The guys I know use the Ford Trac-Loc on the street and Detroit Lockers on
the strip. Ford made a couple of different clutch type limited slips.
The Equa-Loc is the earlier version. Also, there were 2-pinion and 4-pinion
Trac-Locs. The 4-pinion variety are much stronger than the 2-pinion.
If you use the Trac-Loc, don't use lube with friction modifier. Instead,
get the Ford friction modifier in a bottle and only add enough so the clutch
discs don't chatter around tight turns. The Detroit Locker is expensivebut
but very strong.

You can substitue a solid pinion bearing spacer for the crush sleeve to adjust
the pinion bearing preload. Under hard use, the crush sleeves can collapse
and unload the bearing preload.

I don't know if they make a Daytona pinion bearing support for the 8" but its
highly recommended for 9". A friend kept killing his 9" in 428CJ powered Cobra
replica (11 seconds in the 1/4 mile on street tires) until he installed one.

Dan Jones

roverman · February 19, 2013, 11:37:55 AM

Clan, all good info. It appears 31 spline axles are available. I suspect the iron housing is slightly stronger than the aluminum ? New 4 pinion "track-loc",for good prices on ebay. If I buy axles and a posi, might as well opt. for 31 spline ? Thank you, roverman.

roverman · February 19, 2013, 02:08:53 PM

Currie says "no way" to 31 spline axle, in an 8" case. Stock axles are rated at 280hp and theirs is 400-450hp.Your results may vary, use caution when applying clutch and throttle ! Cheers, roverman.

BlownMGB-V8 · February 19, 2013, 02:32:49 PM

I still say you have to go by ring diameter, provided the other parts are up to snuff. (8" parts are, MGB parts are not). General rule of thumb, 8" is good for 300-400 hp, 8-1/2" is good for 500, above that go with 9", etc. Metric sizes are equivalent. So a 200mm equals 7-7/8 and is roughly equivalent to the stock R&P but may have stronger axles and spiders and matches the lower part of that 300-400 range. A 7-1/2" would be a reasonably good choice in the 250-300 hp range.

Bear in mind you can exceed these guidelines without breaking the axles and much depends on how you drive, but if you use full power at any speed, whether the tires slip or not, R&P life might be considerably less than you expect. I flat wore out a stock R&P that was in fine shape in less than 20K miles behind about a 300 hp motor. That ring gear is real close to being an 8" diameter. So if you want it to last and you like to feel the motor pull, don't go minimalist on your axle size or you might be changing them out a lot sooner than you'd like. You don't need to go overboard either, an 8.8 or 9" axle is way more than any MGB is ever likely to need, unless it is permenantly fitted with wrinklewall slicks and all that goes with them.

Jim

roverman · February 19, 2013, 07:09:54 PM

I'm starting to think this 8" , with full floating axles, is better suited for my 4L., Huffaker TR8 ,than a 9". I will do several kinds of racing and will need "easy" changing of ratios-just short of a quick change. This makes the 8/9" a better choice than the TR8 diff., which has maybe (2) ratios available, and a real pain to change/set-up, in the car or bench. I suspect the 8" has, just slightly more drag, than other comparable r&p's. Onward, roverman.

Moderator · February 19, 2013, 09:07:34 PM

8" full floater... so are you thinking Speedway's "Mini Stock" - like Phil is using on his RV8 GT2 car?

roverman · February 20, 2013, 05:37:23 PM

No QC for me, too many parts, more drag and no oem look. I would "like" bolt-on snouts, but no luck yet. Onward, roverman.

bashby · April 01, 2013, 11:52:06 PM

I have been told that a 8" Ford was good for 400 HP., although it is torque that shreds them... I have 4.11's and an Auburn LSD in my Ford 8" (behind a turbocharged 1.8 liter) which is in my Sunbeam Alpine SV.