what's the best style differential?

[megaladon6]

for primarily street driving what's the best one that will work in a buick 8.5in rear? right now i'm planning on a eaton detroit truetrac.

[70bird]

What kind of power are you putting to it? Plan on power mods?
Truetraks are great.

[megaladon6]

i figure my engine puts out a max of 400hp and 450tq.
i'm keeping the 200-r4 but am getting a 2500 stall converter.
the rear suspension will get stronger parts but i'm sticking with the GM designed 4-link. i'm sure that i won't be able to resist doing the occasional burnout on the street, but it's not a drag car(maybe once a year). i have 275/40/18 'vette tires/wheels in back.

[70bird]

oops

[70bird]

I'm no drivetrain expert here by any means, but here's my .02 cents.

Sounds like you are making decent power, and I know Buicks can make some big torque #s down low. If you plan to street drive and occasionaly drag race you shoud be ok with the 8.5 and truetrack, maybe some beefier axles wouldn't be a bad idea. Remember, doing burnouts does not put your axles to the test, but if the car really "hooks up" repeatedly, your gonna' find out where the weak link is pretty quickly.

With that said, get the best and biggest you can afford, keeping in mind future upgrades to power output so you don't end up spending more later. I always try to over-build as far as my wallet will let me.

I ran a stock 8.5 and axles in my Trans-Am for years behind a pretty hot 455, and I drove the wheels off it. Never any rear end problems.
If you are running a full size Buford, (Heavy car) than you might consider stepping up to a 12 bolt or a Ford 9" if you are going to really romp it Mark

[megaladon6]

it's a 87 monte, i just want to get rid of the notoriously weak 7.625 rear for something reliable. i will be getting rid of the c-clips, and getting it professionally rebuilt with new gears and 30 spline axles (at least that's the plan). i really don't want the diff to be the weak point.
actually i'm starting to wonder about the truetrac. eaton's website says that it will spin one tire then transfer the power and equalize both axles. i wonder if it will hold up to me. or if should go with a standard clutch disc style. this is my first build, that's why im so clueless. sorry for the aggravation

[70bird]

it's a 87 monte, i just want to get rid of the notoriously weak 7.625 rear for something reliable. i will be getting rid of the c-clips, and getting it professionally rebuilt with new gears and 30 spline axles (at least that's the plan). i really don't want the diff to be the weak point.
actually i'm starting to wonder about the truetrac. eaton's website says that it will spin one tire then transfer the power and equalize both axles. i wonder if it will hold up to me. or if should go with a standard clutch disc style. this is my first build, that's why im so clueless. sorry for the aggravation

I may be getting past my own true knowlege here, but I am pretty sure the the clutch types do the same thing, just not as well. If you want to have true "posi", I think you will need to go with a locker.

I am not a drag racer, so I have never seen the need for a locker in a street driven car. I do have ARB lockers in my Jeep, but these require an on board air comp. to operate. They work relly well for that app. as when they are in the unlocked position they act like a open diff. Very expensive set-up though.

[megaladon6]

definately don't want a locker. i don't really like driving in a straight line. i just want to be sure that i won't snap the truetrak.

[70bird]

"i don't really like driving in a straight line."

LOL, my driving style tends to be more sideways too!

Just get the best you can afford to buy, the Eaton unit is very strong!
Like I said earlier I ran a STOCK 8.5 w/ limited slip for years without probs. Just gotta put the additive in there when you change gear oil so you don't get clutch chatter.

Maybe someone else can chime in here to clear up differences between the different units. I can see I need to learn more about this myself.
Mark

[parsonsj]

Let me dispel the urban legend that lockers don't work on the street, and are only good for drag racing.

I've got a 35 spline locker setup that I drive all the time. The only time I notice it is when I'm driving in reverse and turning, like when I'm backing out of a parking space. Then I can hear the clicking. Otherwise, it isn't noticeable at all.

Likewise, I've done full on HPDEs on big tracks (Road Atlanta) without noticing the locker, and I've done autoX as well. I didn't notice it there either.

Lockers are very strong, don't require special lubricant, last a long time, and work the same way new and when broken in.

It's at least an option.

jp

[70bird]

Let me dispel the urban legend that lockers don't work on the street, and are only good for drag racing.

I've got a 35 spline locker setup that I drive all the time. The only time I notice it is when I'm driving in reverse and turning, like when I'm backing out of a parking space. Then I can hear the clicking. Otherwise, it isn't noticeable at all.

Likewise, I've done full on HPDEs on big tracks (Road Atlanta) without noticing the locker, and I've done autoX as well. I didn't notice it there either.

Lockers are very strong, don't require special lubricant, last a long time, and work the same way new and when broken in.

It's at least an option.

jp

Wasn't bashing lockers in general, and certainly don't want to add to the myth that lockers don't work on the street, becuse they do.I say that not ever having used one personaly. but having ridden in 1 car with a locker, (in a street/strip car, man, did that thing hook up), and the ratcheting was definitely noticible at slow speeds while turning sharply. I didn't think it was objectionable, but I wouldn't want that car for my DD either. IMO, it's much like any other performance mods we do to our cars, in that, they most all make compromises, and many make sacrifices in creature comforts for the performance we crave. We just get to decide our priorities, and how much is too much. Mark

[merlinpro69]

For what it's worth, I love my locker, I have used my 31 spline locker in my camaro for almost 20 yrs...same locker...it's been drag raced with a blown BBC 427 and and has a fair amount of street miles too.

Yes, somtimes they make some weird noises, scared me the first time I heard them, and its not all the time either, but now im used to it.
Kinda like having a solid roller cam...you know it makes some lifter noise, but it's ok, its supposed too!
I never had luck with clutch type units...prob just my bad luck. And the units I did have made some noise also, especially around corners...worse than the locker at times, and that is with the correct fluid & additives.

I can say you definatley have equal power to both wheels with a locker unless you run the teeth off the gears!

I would say though, if ya not making to much HP, go with a clutch type as some of the guys have recomended.

I wouldn't mind a 12 bolt again, but "I" have not been happy with the clutch type units. If they made a true locker for the 12 bolt, then....