Hello all,
I am building a Dodge Dakota. I have installed a E Body 8 3/4. It has a 489 case, that came out of a 73 D150. It is a sure grip. I had someone put a Richmond 3.90 gear set in it.

With the truck up in the air both tires will spin together in the same direction as one would expect. When trying to do a burnout I am only getting one tire to spin. I'm assuming the clutches are wore out, but I don't know enough about them. Could it be something else such as axle bearing preload? It is the only thing I can think of other than the clutches are junk. Is there a way to check the clutches without taking it apart?

I've not delt with the rearend gears much, and with the local guys wanting an arm and a leg to fix what I have I think I may try it myself. If the clutches are a pain, I may just install a spool.

Thanks in advance,
Sean

Have you changed the gear oil, and if so, did you add friction modifier?

I'm going to assume it still has the cone type sure grip , if so that is your problem , they are not designed to be rebuilt , they can be machined so the cones are not bottoming out but it's only going to happen again. They are garbage by design , they grind themselves into tiny chips of metal everytime it goes around a corner.

There is a Korean sourced copy of the dana/spicer clutch type that's less than 300 and I've heard good things about it , save yourself and just get that.

You do NOT want a spool on the street.

Hey Fat_Mike,
I probably have 5 miles on it and yes, I added Friction additive when I filled it. I've only driven it down the road a few times to shake it down.
Thanks

JohnRR,
How do you tell if it is the cone type? I will google search it. I will probably pull the center section this upcoming weekend.

Thanks

Thanks Stumpy,

I know that a spool can be dangerous and can chew up some tires, put it will probably be 90% drag vehicle.
Thanks

This may help.

http://www.moparts.org/Tech/Archive/axle/13.html

Who put the gears in it ? Now that the gears are setup it's not to hard to change out the diff , check current backlash setting and reset the backlash after you change the diff. You'll need new bearings for the diff.

Look at the link above , the cone type is the top picture , it is easily identified by the springs in the window.

I put a 35 spline spool and axles in my old pump gas Duster, I used an early(1964 Dodge B body) B body 8 3/4 housing and had it cut down to be 2 inches narrower than the stock Duster 8 3/4 housing. I built that car to race the blacks guys in Los angles on the streets It was a ladder bar car with coil over rear suspension, stock gas tank.
it was a little bit of a pain to back up while making a sharp turn to back into a parking spot that had a lot of cars in the lot, same thing on going forward around tight corners. Other than that it was good
I didn't have back brace put on that housing and I ended up bending the passenger axle side of the housing really badly, it broke the welds of the housing ladder bar mounts off of the housing doing a burn out That was really lucky for me, if it had broken while racing or driving it on the streets it I may have lost control and wreck the car
I bought used Dana 60 3/4 ton pickup housing out of a junkyard that had one ruin end on it by spinning one outer wheel bearing inner race, I had it narrowed and put new ends on it and love it from day one I used a spool in it also
IHTHs

I will add to check the back lash in 3 or 4 positions noting them on the gear, try to get as close as possible the the existing numbers

Hi JohnRR, do you have anymore info on the Korean diff copy? Did a google search and got some weird results but not what I was looking for.

There's nothing wrong w/ a spool on the street. Slow speed turns require a little more effort and pushing the car while turning is difficult. Other than that, you'll probably never notice a difference.
Don't believe the myths about wet roads and curves are dangerous w/ a spool.

do NOT search for korean rears..................

Dakotaman - take your truck over to an empty parking lot and do 10 to 20 figure 8's (slowly). The friction fluid has to get in-between the cones.
Same thing happened to me on my 489 case.

friction modifier solves a problem of the diff binding up and not allowing a ‘limited slip’, his problem is UNlimited slip from worn out cones.

Is the one Dr Diff sells worth the extra buck and a half - I would think it probably is?

$395
https://www.doctordiff.com/8-3-4-clutch-type-sure-grip-powr-lok.html

$236
https://www.amazon.com/Limited-Slip-Differential-Chrysler-Sure-Grip-Power-Lock/dp/B0CMTVQ7S7

lol Too late! My computer now smells funny…

I would not buy the china one on amazon.

I'll see the guy that told me about the Korean sourced one and find out exactly which it is .

Dr. Diff is doing something extra to the ones he is selling so that would cost extra over his cost to buy the unit