Demon rear end noise

[Wylde1]

As mentioned awhile back when I joined this site, I had finally got my '71 Demon on the road after it sitting for 5 years with some 4-speed problems. I lost interest and just let it sit.

But on my first drive there was a noise coming from the 8-3/4 rear when going around a corner. Also the shifter rods needed adjusting because I couldn't get the shifter into 1st gear. 2, 3 and 4 worked fine. My guess on the rear was something's wrong with the spider gears.

Because I was busy with other life stuff, I decided to trailer the car 40 miles away to my transmission guy who's also a Mopar guy. That was on June 27. At the time I told him to take his time. I figured I'd get a break on the bill and it'd be done in a month. My parents live out that way and when I'd visit them I'd swing by and see if there's progress on the Demon. Each time I was told that they're too busy to look at it. So last week with still nothing done, I put the pressure on him to get it done before the snow flies *please*. If I knew it was going to take this long, I would have saved the U-haul trailer rental and just brought him the center section and played with the 4-speed myself.

So today I get the call that he took the center section out and the spider gears are broke (didn't I suggest that was the problem 3 months ago?). But he cannot get parts for it. It's a 489 case with 5:38 gears and a clutch type sure grip. His suggestion was to borrow a center section to get the car mobile and get it out of his shop because it's now taking up space just sitting there. Or he will sell me a new Auburn sure grip for $950 plus his labour. I thought $950 is alot for a sure grip and did some searching online.

Here's what I've found:

Randy's Ring and Pinion has parts for the suregrip (that they call a posi).

Yukon Power Lok positraction internals for Dana Spicer 44 and Chrysler 8.75” with 30 spline axles. Does not include clutches. $255.54
http://www.ringpinion.com/ProductDetails.aspx?ProdID=3157

They also have sure grip units for a few bucks more.

Yukon Powr-lok Race $410.97
http://www.ringpinion.com/ProductDetails.aspx?ProdID=1829


Auburn Gear Pro Series $513.51
http://www.ringpinion.com/ProductDetails.aspx?ProdID=1836


Detroit Locker $510.18
http://www.ringpinion.com/ProductDetails.aspx?ProdID=1832


True Trac 30 spline $545.81
http://www.ringpinion.com/ProductDetails.aspx?ProdID=1803


True Trac 33 spline $529.95
http://www.ringpinion.com/ProductDetails.aspx?ProdID=1805

Randy's axles all state 5 x 4.5 and must use green bearings


Moser Engineering has sure grip units.

True Trac 30 or 33 spline $630
http://www.moserengineering.com/Pages/Differentials/truetrac.html


Auburn Pro Series $470
http://www.moserengineering.com/Pages/Differentials/auburnlimited.html


Drive Train Specialists also has sure grip units.


Posi Serv Internal parts. 30 spline axles. Sides and spiders only. $271.50
http://www.drivetrainspecialists.com/categories/chry/chry-875-489/products/product-182.html


True Trac 33 spline $468.89
http://www.drivetrainspecialists.com/categories/chry/chry-875-489/products/product-5436.html


Air Locker $653.57
http://www.drivetrainspecialists.com/categories/chry/chry-875-489/products/product-157.html


National Drivetrain has sure grip units as well.


Detroit Locker 30 spline 2.76 – 4.56 $586.60
http://nationaldrivetrain.com/shopsite_sc/store/html/dlock_chrysler.html

Auburn Gear Pro Series $487.10
http://nationaldrivetrain.com/shopsite_sc/store/html/auburn_pro_chrysler.html


Even with the dollar difference, shipping and duty charges any of these units will save me money compared to his $950 price.

I like the True Trac set-up, but they need green bearings on the axles because the True Trac is wide open inside and don't use any thrust buttons to handle axle to axle thrust transfer. Or I could copy what Mopar Action did and keep the stock threaded adjuster and order axles 3/4" longer than stock to make up the length of the thrust buttons. This would let the axles but up against each other to transfer the thrust load.


So, do I buy just the sure grip parts from Randy's for $255 or get a True Trac for anywhere from $468 to $630 depending where it's from? I'd like some high strength axles, because I don't think I can trust the stockers with 5:38 gears and Mickey Thompson ET Street tires. Or does anyone have a clutch type sure grip that's shot and want to sell me the spider gears out of it? Any other preferences? I don't want to do the job twice. I'd rather build a strong rear end once even though it's going to cost a few $$$ now.

In the mean time DemonDave is loaning me a center section so that I can get the car rolling tomorrow.

Whew!

 

[demon seed]

Sorry but I'm missing something here, you can go to Mancini, for instance, and buy the complete center section for 1200 bucks with your choice of gears and auburn posi included. Maybe he's doing ya a favour asking ya to get your car out of his shop.

Terry

 

[Wylde1]

Thanks for the info. Isn't the Auburn sure grip the cone type often referred to as the "weak" suregrip? And then I'd still want to upgrade the axles as well. Gettin' into some serious coinage.... but if that's what it takes....


Thanks again.

 

[demon seed]

Thanks for the info. Isn't the Auburn sure grip the cone type often referred to as the "weak" suregrip? And then I'd still want to upgrade the axles as well. Gettin' into some serious coinage.... but if that's what it takes....


Thanks again.

I was just using Mancini as an example pricing wise and yes the auburn is the cone type but I think the design has been giving a bad rap over the years. I would still, given the choice go to the disc plate type posi design for street and strip myself cuss it's the devil you know.

Terry

 

[DemonDave]

Have you ever considered just running a spool in the diff? It's cheap and will never wear out or break. You might have to upgrade to a 35 spline Moser (or other) axle but axles are cheaper than $950 sure grips! It'd be an install and forget deal... except when you're making tight turns when the chirping rear tire would remind you it's in there. Still, Kevin runs a spool in his nasty blower Coronet on the street and has no issues, even at the Tim Horton's drivethru!

Anyway, I told Kev last night that was loaning you his 4.56 and he didn't seem to care much. He might be here today when you come by, if so, ask him in person to make sure he's really cool with it.

See you this afternoon!

 

[Wylde1]

You know, I was thinking about a spool early this morning. A guy I used to work with put one in his '72 440 Challenger a few years ago and he's had no complaints with it (although he didn't upgrade the axles). You're right. You do know it's there in tight turns. But the Demon ain't no corner carver anyways.

One more added bonus. For the $950+++ I could get a spool, Moser axles and a new set of 28x13.5x15 ET Streets. Sounds like a plan.

 

[1969GTS]

I think Randy's ring and pinion quoted me $1200 with a clutch style posi in a 489 case. I picked up a good used 391:1 for $350.

Dave