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swapping out an 8 3/4 rear

Posted By: ashburnmike

swapping out an 8 3/4 rear - 12/26/08 04:49 PM

Hello all,
I'd like to try and swap out the 3.91 chunk and replace them w/3.23 in my Dart. What does it take to do this. Do I need special tools? Is there anything I should be aware of before attemping this?
thanks
Mike
Posted By: RapidRobert

Re: swapping out an 8 3/4 rear - 12/26/08 05:00 PM

swapping one chunk for another? You only need a gasket w cement(my preference), several qts of the appropriate gear oil, a small bottle of the sure grip additive, Check & see if the flanges take the same size u joint, get the pumpkin seated all the way into the housing,only pull the axles out far enough for the pumpkin to come forward, adj end play when you're done. & last but not least give me 1st dibs on the 3.91
Posted By: ashburnmike

Re: swapping out an 8 3/4 rear - 12/26/08 05:10 PM

sure thing..you have first dibs. If that's all there is to it,great. it seems too easy. I didn't realize how that low a gear really runs up the rpms @ 55 mph.
Posted By: stumpy

Re: swapping out an 8 3/4 rear - 12/26/08 05:15 PM

Here's a little toy for seeing what gear and tire changes do to RPMs. http://vexer.com/68rt/speed.html
Posted By: RapidRobert

Re: swapping out an 8 3/4 rear - 12/26/08 05:19 PM

Quote:

sure thing..you have first dibs. I didn't realize how that low a gear really runs up the rpms @ 55 mph.

yes that will be difficult to deal with but I feel up to it . The only other thing I can think if is if both of the chunks have the thrust buttons on there where the axles but together you wont have any problem with resetting your end play & you want it on the low side ~ .010" or so.
Posted By: NTOLERANCE

Re: swapping out an 8 3/4 rear - 12/26/08 05:21 PM

Regarding the thrust buttons, they have a tendency to fall out, so keep an eye out for them.

Youll need them for reassembly, assuming you have all oem bearings and components.
Posted By: ashburnmike

Re: swapping out an 8 3/4 rear - 12/26/08 05:22 PM

how do you adjust the end play?
Posted By: RapidRobert

Re: swapping out an 8 3/4 rear - 12/26/08 05:28 PM

there is a threaded adjuster on the passenger side located on the axle flange in between the brake shoes. just have the axle up on 2 jack stands during all of this(the R&R & the adjusting)
Posted By: ashburnmike

Re: swapping out an 8 3/4 rear - 12/26/08 05:43 PM

thanks. I wish I had that when the 3.91's went in...it's right on the money w/ the current rpms.
Posted By: ashburnmike

Re: swapping out an 8 3/4 rear - 12/26/08 05:45 PM

Quote:

there is a threaded adjuster on the passenger side located on the axle flange in between the brake shoes. just have the axle up on 2 jack stands during all of this(the R&R & the adjusting)



How will I know when it's adjusted correctly?
Posted By: meepmeep70

Re: swapping out an 8 3/4 rear - 12/26/08 05:54 PM

you want no more then ten thousandths of an inch,you may want to borrow or buy a dial indicator,fairly cheep and handy to have. good luck
Posted By: ashburnmike

Re: swapping out an 8 3/4 rear - 12/26/08 05:55 PM

Quote:

you want no more then ten thousandths of an inch,you may want to borrow or buy a dial indicator,fairly cheep and handy to have. good luck



Thanks for the help everyone...off to the garage
Posted By: MoparforLife

Re: swapping out an 8 3/4 rear - 12/26/08 07:52 PM

Go here for the adjustment:
http://www.moparts.org/Tech/Archive/axle/12.html
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