Rear end dissapointment

[CaptMarvel]

Ok, I finally got around to jacking up the rear of my 68 R/T and found the rear wheels spins opposite ways! No sure grip.... Im sure this question has been covered at some point), but being that I do have the 742 rear end case, whats next? Can I get the sure grip parts new? I dont really want to spend the rest of my life looking for one in a scrap yard, only to find out it is toast or something. I am kind of bummed, I must have the only true 68 R/T with a 440 that didnt come with a factory sure grip I have always been suspiscious because my fender tag is left blank where sure grip should show....Oh, well, I plan on putting one in, wheres the best place to get the guts?

[myk]

Don't be too upset, limited slip differentials were not standard from the factory even for axle twisting R/T models.  As such, there are plenty of cars without them.  You can consider doing what I'm planning on, which is having a limited slip gear assembly installed in the axle; it's going to cost me about $600 or so...

[derailed]

Im in the same club. Keeps your eyes open because there out there. I picked up a nice 742 sure grip unit for $250 last year and the guy threw in some new seals and bearings

[694spdRT]

Sure grip wasn't even that common in 440 R/T's so keep your chin up. There is nothing wrong with using your 742 case and getting a sure grip unit and whatever gears you want. It is actually the preferred case because it is rebuildable vs the 489 cone type.

[TylerCharger69]

So...now my question is, will a 742  case bolt up where a 489 once was???

[derailed]

If your changing the entire case I believe all the 8 3/4 are interchangeable after 64.

[Silver R/T]

I thought if one wheel spins forward and the other one spins backwards it is sure-grip/lsd

[TylerCharger69]

No...if they spin opposite directions....it's just an open differential.

[694spdRT]

So...now my question is, will a 742  case bolt up where a 489 once was???

Yes, the axle housings and axles were the same. I swapped a 489 sure grip with 3.55's in place of a 742 with open 2.71's in my '68.

[Chryco Psycho]

Auburn has brand new cone style sure grips available
all carriers will swap into 8 3/4 housings , the 741 , 742 , 489 & the early small pinion , the axle spines are all the same
the sure grips will also interchange between all carriers

[Silver R/T]

how much would be average cost to rebuild a sure grip?

[resq302]

Chryco, you beat me to it.  I had my third member rebuilt last year and it is the 489 casing.  It did have an open rear in it and he was able to put a sure grip unit from a 742  casing in it.  Hooks up really nice now!

[Chryco Psycho]

well the clutch type can be rebuild , the parts are over $100 + the labor to reset the gears so....

[Runner]

if your just doing a clutch pack the kit is about 40 bucks , if your buying a used surgrip and paying for a rebiuld kit then paying for someone to rebiuld it and set up the gears  then id call dr diff in montana , he is a super nice guy and is priced very competitivly.

   i just rebiuld a 489 case with a solid pinion spacer, a set of strange/us gear 4.10s a set of his street clutches ( becasue i was sick of the rear tire dragging around with a tight suregrip), a bearing kit. with oil and everything i was under 400 dollars however i had a clutch type suregrip to start with and i did all my own work. i personally wouldnt spend much money on a aburn  cone style suregrip,  they just havent held up when ive abused them ( my roadrunner) however they seem ojk in a light duty setup.

    another thought is, if you want to buy a drop in pumpkin all done they are around 950, then if you buy after market axles they are around 350. a new dana 60 is around 1700 last i checked and its much stronger.

[CaptMarvel]

So, it sounds like I'd probably want a clutch type sure grip for my 742? Who would I get in touch with for installation around central CA?

[rt green]

what about the 741 case? are they any good? i've got what i think is a 741  center, and it is a sure grip. i'd have to look to be sure of the case number.   bruce

[Silver R/T]

how hard is it go change open differential to sure grip?

[dodge freak]

You need to pull both axles out, left & right and unbolt the main caps the whole carrier comes out with the ring gear. The new posi unit takes the place of the old carrier so the bearings need to be change or swap and the ring gear needs to be swap over-new ring bolts good idea- then it needs to be shimmed up right -takes a dial gauge and some ex.

I let a pro do it or you might have a loud rear end that might break.

[Runner]

while a 741 is the weakest of the group, they will hold up fine in most cases.


   to install a suregrip in a open carrier all you have to do is check the backlash on the ring and pinion,remove the open carrier from the pumpkin ( remove the 4 cap bolts and adjusting screws)  remove the ring gear and install it onto the suregrip, make sure you have the correct beariing and race set ofr the suregrip carrier. set it into the pumpkin with the races put the caps on ( making sure to install them on the samer side they came off), leave the bolts finger tight and install the adjusters. set  the back lash on the ring and pinion to the same as it was before making sure it was in spec. remove the cap bolts one at a time and loctite and torque to spec and install the adjuster locks and loctite the bolts for those.  recheck your back lash and then put the pumpkin back into the car, set axle bearing preload fill it with oil and suregrip additive and go out and start pinstriping the town with both tires.


    the clutch style ring gear bolts are a little smaller than the cone style , however you can buy new gear bolts for a a cone style and drill out the holes in the clutch style carrier to accept the larger ring gear bolts.  also ring gear bolts are left hand threads.

[Silver R/T]

do I have to change axle bearings?

[Runner]

no , but you will still need to set the bearing preload

[Silver R/T]

Ive got no idea how to do that

[Silver R/T]

No...if they spin opposite directions....it's just an open differential.

would broken sure grip spin opposite ways?

[Runner]

 any chiltons manual will tell you how to set the axle bearing preload. the adjuster is on the passenger side axle. one of the axle retainer nuts has a locking tab on it.

[CaptMarvel]

So doing a new clutch type suregrip in the 742 case is a possibillity right? With all new parts? available where? I guess any reputable local rear end shop should be able to put it all together right? Where to find these new parts though? (I love junkyards & am not adverse to spending the day out there, but I really want to put all new stuff in if possible) Any insight appreciated...Im kind of out of my normal element with rear end gears & stuff What gear ratio options will I have with the sure grip setup? Whats the best for just wanting to light em up every once in a while on a Saturday to scare the wife & make the kids cheer, not really planning a dragstrip future...Anyone?

[Runner]

call this guy  http://members.aol.com/doctordiff/   you wont get better service or knowlege anywhere else. ask for cass

[Lifsgrt]

Bruce, if you have a posi 741, it should have a clutch type sure grip diff in it.  The 741 is the weakest, so if you're concerned about breaking it, look for a 742 or 489 case and you can swap your diff into it, but you'll need to buy the correct gears for the case you decide to use.  The 741, 742, and 489 all have different ring and pinion designs.

[Nacho-RT74]

just got a new Yukon Street SG clutch kind on $355
http://www.marketworks.com/StoreFrontProfiles/DeluxeSFItemDetail.aspx?sid=1&sfid=92390&c=68053&i=18027296


Randy sells those on around $470

[Silver R/T]

thats a good deal

[Mike DC]

I'd love to put one of those new switchable electric LSD-or-fully-locked setups in my 8.75" axle. 

IMHO this would be the ideal fun street setup.  But they're all pretty expensive, and it's a little too early to know how long they'll last in the real world yet.