3.07 limited slip voodoo

[Mad Max]

There's a thread on TDR talking about a limited slip for a 3.07 D71.  It sounds quite plausable, and here is my recap.  Can anyone confirm or deny?

Some of the basics I want to confirm:  D71 and D70 carriers are interchangable in the housings (up to 3.54 gears) but the respective axles are not - need to swap axles to match the carrier.

Here's my reply...

...so if I understand this right...if I have a '93 srw D70 (with a factory limited slip and 3.54 gears in it) sitting around, and my daily-driver truck has a '91 srw D71 under it.......and I want to install the limited slip from the 70 into the 71....I'd need to pull the 32-spline axles and the carrier from the 70, unbolt the 3.54 ring gear, bolt up the 3.07 ring gear to the 70 lim slip carrier, then install the 70 carrier into the 71 housing, and then install the matching 70 axles in the 71 housing, and that's how it's done??  If so, sweet - I'll be doin' it.

- Sam

[DODGEBOYS]

yup thats pretty much it / you also gotta change the pinion / l,d say it would be easier and faster to just swap the complete rearends / 4 u-bolts- two shocks - brake line -driveshaft- two e-brake cables and your done /  instead of tearing both a part

[88_mopar]

yup thats pretty much it / you also gotta change the pinion / l,d say it would be easier and faster to just swap the complete rearends / 4 u-bolts- two shocks - brake line -driveshaft- two e-brake cables and your done /  instead of tearing both a part

If i read it right, he has a 3.07 open, and a 3.54 lsd, and wants to combine them to have a 3.07 lsd.

Okay gonna show my ignorance here. Could you just swap the 3.07 ring gear into the d70? What are the differences between a 70 and a 71?

[Mad Max]

well yeah I guess that'd be the most logical alternative - the 70 has a lot less miles on it so I might just look at that option .

[nosights]

D70 has a bunch of variants and they have different pinion offsets. Do your homework and/or call Randys R&P to verify...or just switch axles

Dan

[Mad Max]

...but...but..this IS my homework .  Actually I just got off the phone with Randy's and had a very good conversation with Brian in sales.  Okay, so according to Randy's, here's the real dirt, and it's very interesting -

Bottom Line - YES - a limited slip is available brand new for a factory D71 rear axle with 3.07 gears.  However, you won't be buying a 3.07 lim slip unit...you'll be buying a 4.56 lim slip unit - here's the voodoo

First off, the 3.07 r&p will not work in a D70 housing, only a D71.  This is because of the 31/32" offset housing for the 3.07s.  Other offests are 1/2" and 5/8" but I'm nto sure which are for what.

Second,...according to Randy's...the 3.54 carriers will not work in the D71 housings; you'll need a 4.56 carrier, because of the offset - 4.56 carriers have the same 31/32" offset, and therefore the 4.56 carrier (and associated factory 'power lock' limited slip) unit is what we need to get a nice, new limited slip in our 3.07-geared D71s. 

The cost for both 'parts' (carrier unit and power lock guts - two separate part numbers) is $633.70; $270.26 for the carrier and $363.44 for the guts.

So...I will be doing this upgrade when I get the cash but that'll be a while as this mod is low on my priority list, but it is on the list.  So, if anyone wants to do this please post up with the results!

...more to follow...

- Sam

[hp383]

Sam, does this mean that a 4.56 SG from a Dana 70 would swap into the 3.07 and allow you to keep the 3.07 ratio?

If so i could find a used setup and save money.

[Mad Max]

....unfortunately I don't think so.  If I understood Brian right, they have a 4.56 carrier that is also 32 spline, and while I don't think it is a standard Dodge carrier it is maybe standard for something else and just happens to also fit the oddball D71s.  I have to believe that no one would make a carrier specific for a D71 - we just can't be that lucky...but in this case they apparantly do have one.  I don't know what it's originally intended for, but it seems that 32-spline 4.56 carrier, and respective power lok guts, is the way to go, and if I understood right...it's the only possible way to go.  I haven't done it myself so I can't say for absolute certain about all this, but I will be trying it soon as the funds line up, and I'm happy to be a guinea pig

[Mad Max]

and this is the corresponding thread over on TDR.  More tasty bits of goodness -

http://www.turbodieselregister.com/forums/1st-generation-ram-forum-1989-1993/216073-limited-slip-3-07-gears-2.html#post2091515