99DWPTA

iTrader: (10)

i'm a noooob to rear ends so bare with me



Well time for a new rear end. i know theres a million post to help me out but. i cant decide what i need.

Its a daily driven car
looking for somethign to support 600whp and not break
it will see the track and or drag radials not very often maybe 5 times a year at the track.

NOW
i want around a 373 gears as i have an A4
i like the detriot locker
So whats gonna hold up for my application
and i'd like to keep ABS so whatever i have to do to keep that.
and how much $ am i looking at
whos the cheapiest on here to get it from

thanks everyone

koolaid_kid

iTrader: (21)

This is going to be fun to watch. I'm not razzing you, btw. Best of luck.
And remember, the cheapest does not necessarily mean the best value.

white mongoose

iTrader: (3)

you should check scott 4m dls got some great deals i went with 9' 4.11 true track love it got the 9 cause my car is an m6 and leaving hard of the hole

staringback05

iTrader: (8)

i think a 9inch tru trak like stated would be fine....373s would be a good gear to go with also...your car being an a4 is going to be preloaded when it gets to the line so the cars not going to beat on the rearend like a manual will....i dont think youd be happy with the detroit locker...esp if your not going to be taking that car to the track alot

monzaz

Well I have installed plenty of Eaton clutch type units that have been holding for a while. Get some good aftermaket axles and a good installer and tell him what your doing with the car and hopefully they can set it up proper for your application. I really have seen 7.6 rears take some punishment. Just sounds like your not racing alot and want the abs working etc. this is a pretty good set-up. if you need more lock-up buy the 800 pound spring preload kit and it will chatter in the corners but stay locked good. Again it is your choice to how original you want to stay with the car. Good luck with your choice. Take care, Jim

J D Race.com

99DWPTA

iTrader: (10)

scott at driveline solutions told me this is what i would want

The Ford 9 inch would be the way to go I have them for $2375.00 shipped in 4 boxes so you can retain your stock ABS and brakes. I use a Strange S casting, Truetrac diff., Daytona support, 1350 yoke. Moser housing and axle package with TA mount

is this a good price.

Predator

I think it's a fair price.

staringback05

iTrader: (8)

yea thats a pretty nice setup....something you wont be breaking easily

onfire

iTrader: (17)

https://ls1tech.com/forums/gears-axles/742497-question-about-rear-ends-my-street-ttta.html

99DWPTA

iTrader: (10)

thanks guys

INMY01TA

iTrader: (1)

Personally I think your fine with a 12 bolt for an A4.

99DWPTA

iTrader: (10)

12 bolt and 9" are relatively the same price so why not go for the best??

INMY01TA

iTrader: (1)

Well I personally know several guys that have 9-10 second F bods that have 400s and all have 12 bolts. I dont think this guy would have any issues with one. Why buy a heavier less efficient one?

Predator

I would have said 12-bolt until he mentioned 600rwhp.

EPP

iTrader: (22)

Put a 12 bolt into a early Chevelle, Nova, Camaro, etc and you can beat the crap out of it, and not hurt anything. Put one into one of our cars with a torque arm, make a couple 4000 to 5000 dragstrip launches, and I can just about guarantee you'll pick up gear noise. If it is a drag only car, you'll never know or care about the gear noise. Drive your car home from the track, and the noise will drive you nuts. I feel the torque arm stresses the 12 bolt housing, causing distortion. We have never seen this happen with the 9 inch housing.

Exotic Performance Plus strongly recommends the Moser nine inch. This rear is even tougher than the Moser 12 bolt, and the horsepower of the late model F Body cars keeps escalating every year, which requires a very strong rear. With the recent introduction of the 6.2L GM aluminum block and the excellent flowing 6.2 litre heads, the horsepower of these cars is going to just keep climbing at a very fast pace.The nine inch will handle the power, plus we prefer the way the torque arm is bolted to the nine inch in the same way the oem rear-end is attached. (This is the only good thing about the stock 10 bolt...) The Moser 12 bolt uses four short bolts to attach the torque arm, and they have a habit of loosening up, even when loc-tite is used. Why the nine inch is stronger than the 12 bolt. The 9-inch has an internal rear-pinion support that also supports the gear end of the pinion to limit gear deflection under high torque loads. This seems to be the major reason why the 9 inch doesn't start whining after high rpm clutch dumps, when the 12 bolt will pick up noise.The 9-inch locates its pinion gear lower on the ring gear to improve tooth contact, than the 12 bolt does.The 9-inch has a 0.125-inch larger ring-gear diameter and internal pinion support than the 12 bolt does. This is not much of a difference, but it is worth noting. Bob

Black02SLPSS

iTrader: (5)

You must have that copied so you can just cut and paste it when a question (and these questions occur alot) like this comes up eh? lol

chicane

Just to clarifiy one tiny but important detail before the mis-information spreads...

The reason behind the 9" having its pinion lower on the ring gear was not to improve the tooth contact. The 9" differential, as a whole, was designed with a spigot bearing. The design use of the spigot bearing is far superior in strength than other 'unsupported' designs. Simply stated, the engineers had to rotate its position from centerline to accomodate the addition of the spigot bearing support into the housing.



My opinion on the subject:

ABS and Detroit = not gonna happen. Lockers, spools and the like dont allow the assembly to differentiate. Between the three and four channel systems, a three channel with a Detroit or other locker would have the easier time with the ABS over the four channel. Whatever your choice between a 12bolt or 9"... I will also recommend the True Trac. There is however, nothing wrong with with an EATON... as I am still running the 40+ year old EATON in my 40+ year old 12bolt without issue... and at that power level no less. But... I would not recommend that you use an 800# pre-poad pack. It just happends to be the biggest contributing factor in premature clutch wear and failure of the fiber clutch packs. The real bummer is... that the newer HD units sold by Moser, Strange and anyone else... have fiber clutches and the 800# spring packs. I myself would opt for an 18 plate solid steel clutch pack and the 600# springs. In fact, in the majority of client chassis, I dont even use the pre-load pack... as I tune the differential to the needs of the driver and chassis.

12bolt or 9" ?? With the noted power level... and the fact that you are looking for a 'cheap' way into something stronger... I'd say 9". There is however, nothing wrong with the 12bolt in this application BTW. My reasoning for this recommendation is that you said it is a driver... and you will only 'see' the track a few times a year. For what you get out of the pre-assembled packages now-a-days... its a great way to get something strong enough for your use... without braking the bank. The 12bolt's that are offered by the same and often named builders around here, will need some paid to attention to detail to yield the same. Its all very simple and near no cost modifications... but non-the-less, something they dont pay attention to.


What is offered, pre-built 12bolt wise leaves you with questioning a few things. What was done to combat weakness in one area opens up the door big time in other areas. First off, ditch the idea of 33 spline axles and useless pre-load cover. The 33 spline axle makes the differential carrier journel thinner (which is where you can not skimp in any strength consideration) and the covers do nothing to begin with... well... ok, they give you a drain and fill hole. But the fill hole is located wrong to begin with ?!?? Uhm... go figure. A correctly designed 30 spline axle will be more than enough as will a steel cover with a pair of bungs welded to it...

Last but not least... if you want it done right the first time... dont just go out and purchase a pre-assembled pile of parts. You are much better off... product and price-wise to have a reputable builder... (like Scott @ DLS) or some others to do it for you.

Remember, mass produced off the shelf stuff... is mass produced off the shelf stuff. If you question this, just look at and read all the threads about this peticular subject. Is your car with its 600rwhp off the shelf ?? Do you really think that it requires a little more attention to detail ?? I do.

Just like what you are doing right now... DO YOUR HOMEWORK. Dont skimp. Unless you want to do this all over again in a couple of months.

revtime

iTrader: (1)

Figures, I have both.
Now I have a spool, does that make a difference with the differential carrier journals?

Next question, why do they offer 33 spline, 35 spline, or even 40 spline axles if they are weaker?

chicane

In the case of a spool... not so much. The construction of a spool is very much different than that of any other carrier assembly. Normally, these are not effected by this too much as the spool itself can be machined thicker in any part of the spline section. Specifically the bearing journel flange. Where the real difference is concerning a spool's strength is in the spline pressure angle and tortional resistance of the material being used.

The size of an axle can be relative to one of two things or a combination of both. Basically, it comes down to material use and design. With the materials being used, it would have to be made bigger to yield the same strength ratio of a better, but more costly material. That right there is the main reason. Its a bandaid to using a better material and keeping the relative costs down to the end consumer. Its almost as bad as the misconceptions of 'gun drilling' axleshafts. Bigger isnt better if you are using cheaper materials.

Albiet, that the only reason to use a larger axleshaft is to utilize the benifits of a greater spline count. When you go from a 30 spline axleshaft to a 40 spline axleshaft... you yield a strength increase from the increase in overall surface area and get to displace the mechanical load across more mechanical surface area. This works great with cheaper materials... and you'll yield a whole bunch more... like even a triple digit % increase... when using even better materials like that of 300M.

If you use a better material, the strength is naturally there and the weight is kept to a minimum due to the fact that you dont have to make a 4140 shaft 2.000" in diameter to have the yield strength as a 300M shaft of 1.275"... and even then... the 4140 shaft still isnt anywhere near the strength of the much smaller 300M.

If you had 2000 hp and could actually hook it up... a 35 to 40 spline axleshaft might be in your best interest. But you dont, and your not going to... so there is no justification for it. You want a better axle, use better material... you want a better beer, use better... you get where Im going with that I hope.

revtime

iTrader: (1)

Thats kinda what I was thinking. I just see alot of 30 spline stuff out there and think, Wow, my 33 spline axles are overkill for what I am planning. I plan on street driving this rear end alot more than track racing and wanted to make sure I am not putting any undo stress on it.

Thanks for the clarification. Good info and might save someone money down the road.