"cheap" locking differentials

[Dora The 4x4'a]

do not worry, i am not going to weld or spider or spool or whatever the term is my rear or front in my ex!.. i am air lockin those.. but since peopel on this thread are familiar with locking differentials.....

i hav an 88 formula firebird i came across and im going to drive it for a little while.. so i thought it might be fun to hav "posi" but i am not goin to swap a posi in or put a locker in..so im wondering how i might go about locking the diff by welding it like ive heard is possible..

thanks for your input
-chris

o and dont gimme crap bout havin a GM.. it was practically given to me! so i wunna hav some fun with it!

 

[454burb87]

Welding the Diff

Just a word of warning on those 80's F-body cars......the ring gear in the axle is only 7.5" in diameter....(dana 30 status) i own an 82 trans am with a 68 302 z28 motor and have gone through 3 ring and pinion sets in less than 20k. As for the actual welding all you need to do is weld the spider gears to the case: however there are lunchbox lockers for this axle check out REIDERRACEING they have it..

 

[Dora The 4x4'a]

so what does the diameter f the ring gear hav to do with it? does it make this a bad idea or something orrr?.. cna u apply the info you just gave me

thanks

 

[IZwack]

Ring gear diameter has plenty to do with it because:

In a non-locked differential, if you stomp on the wheels, you'll probably get the infamous one wheel burnout. The wheel that is happily spinning away like there's no tomorrow has no significant opposing force against it -- meaning the ring gear isnt being stressed (or torqued) as much because the coefficient of static friction is almost always greater than the coefficient of kinetic friction -- meaning its easier to keep the tire spinning during a burnout than it is to initially break the tire free from the pavement. The equal but opposing force thats being applied to the ring gear is of course Newton's third law of classical mechanics (pun intended - Newton would have made a great mechanic ).

On the other hand, on a locked differential, stomp on the gas and the car will probably launch which means the ring gear is being stressed by both the torque coming down the driveshaft and the "equal but opposite" force the asphalt is providing (through the tires, wheels, axle shaft, and finally the carrier onto the ring gear) to launch the car.

Soo... with a smaller ring gear (and pinion gear) and locked differential, the percentage of breaking a tooth on one or both of the gears will be greater because of the increased opposing force (due to both tires not being able to slip as easily). In addition, like most differentials, the one you have probably does not have rear pinion support which will increase the likelihood of pinion gear deflection during hard launches.

 

[Dora The 4x4'a]

thanks a lot for putting that in scientific terms that really put it in perspective and i appreciate it. what would you suggest?

i got this car for very cheap and i would like to just hav some fun in it for these spring/summer months and try to sell it in the winter and get a new truck.

 

[IZwack]

what would you suggest?

Well you can scavenge the junk yards in the area -- Crazy Rays sells complete rear axles for ~$130. Dunno what bolt pattern you have but for example, there are Explorers that come with 4.10s and Limited Slip so that'd be a good option (if the bolt pattern matches or you're willing to run pattern adapters).

You can also say F[ork] it, weld it up, and if it breaks, you can replace it with a better one from a junk yard.

 

[stev0n]

You can also say F[ork] it, weld it up, and if it breaks, you can replace it with a better one from a junk yard.

i second this idea. And if or when it does break try to find the rear end out of an lt1 f-body. I don't know how it is in maryland, but around here LT1 limited slip rear ends are a dime a dozen. A friend picked up 3 with 3.73's for somewhere between $250 & $300, i believe.

 

[Dora The 4x4'a]

thansk both y'all but im actually talkin about locking a firebird^
however your suggestions apply to the GM as well, were jus tlkin GM posis insteada different ford LSs

 

[stev0n]

i was talking about firebird rear ends - either an lt1 trans am or lt1 firebird formula. i'm not sure about the first and second gens, but the 3rd and 4th gen rear ends are pretty much the same and should interchange without a problem

 

[Dora The 4x4'a]

o wow my mistake i read f-body as f-150.. i guess i just skpped over lt1 entirely..sorry i did not read more carefully. thanks for all your input. i'll update the thread if i go thru with this.

 

[Kyle0614]

"68 z28 302 motor" hmmm didn't know there was such a number offered by chevy...perhaps you meant to say 305? "454burb87"

 

[454burb87]

302

GM had the following displacements....

262,265,267,283,302,305,307,327,348,350,400, Small Block

396,402,427,454,455,502. Big Block

it is a 3" stroke and a 4.00" bore
It was an overbored 283 (3.750")

 

[joecrna]

302 Chevy made in the late 60s for the Trans Am racing series. Rules had max displacement at 302cid. Chevy used a 350 and put in a 283 crank. Viola, a 302. Very dominate.

Please tell me you dont have dual 4 barrels. This is a very sought after engine, even with a single carb if not modified. This was designed for high revving road racing, so that rear end must truely be weak. Unless you are running a manual trans and bonsai the clutch at launch.

 

[454burb87]

It is not a dual carb don't worry, and as for the rear axle it is a POS. 7.5"ring gear *picture a dana 30 for your rear axle* that is the equivalant... and Kyle0614 please research before claiming something....

Sorry for the hijack....find a ford 9" from a car and drop that thing in (welding required) you won't break it...or part out a wrecked X...

 

[stev0n]

and Kyle0614 please research before claiming something....

he wasn't sayin you were wrong, he was just saying he'd never heard of a 302 gm engine and thought maybe you mistyped it.

you've gotta remember, the majority of people in the universe only think of the common 283, 305, 350, 400, 454, & 455 motors when they think of chevy or gm.
actually you didn't even put 455 HO down as a big block option (olds' had them in the 60's, buick GSX's and Trans ams in the 70's).

 

[Kyle0614]

x2 ^^ i wasn't saying your wrong either like said above people usually think when they here "302" oh that must be ford 5.0...maybe 10% of car people know chevy had a 302...and BTW yes i know how to search i just wasn't aware of a 302 chevy motor...so either thought i'd ask here or maybe thought you mistyped...just like stevon said...

 

[454burb87]

I didn't think you were calling me wrong...just saying google 302 and both come up....as for the 455 that was a solely buick block, not a chevrolet production. Yes the 455 is a GM block prone to rod throwing...(learned from a jet boat motor my buddies have)! we had fun doin it though!

 

[Kyle0614]

also oldsmobile for the 455 i do believe ...don't quote me though...maybe like in the muscle cutlass...not the ghetto looking ones but the ones like nova's and what not? no?

 

[Dora The 4x4'a]

hahaahahhaaha well putt kyle

 

[Dora The 4x4'a]

..p.s. and as far as i kno those were 454s..