Options for 9" 31 Spline Upgrade...

[bulletpruf]

Fellas -

I'm ready to upgrade the 28 spline small bearing 9" and wanted to check to see if I was on the right track.

Intended use of this '69 Bronco is on and off road, but it won't be a hard core rock crawler. Tires are currently 32 x 11.5 x 15. Plan to add a fairly stout 347 in the not-too-distant future. Trans is currently stock 3 speed, but upgrading to an NP435. Upgrading the front diff to a Dana 44 as well. Plan to keep 1310 u joints.

I'm trying to stay on somewhat of a budget.

I know I don't want a spool or a mini-spool, but is there a consensus on Detroit Locker versus aftermarket clutch style unit versus TrueTrac type units?

-I can try to source a good used 9" nodular case, buy a used NASCAR Detroit Locker from eBay, use my current 3.50 gears, and assemble it and set it up myself.

-I can try my luck with a used one like this one on eBay - https://www.ebay.com/itm/224508623386?epid=1117847662&hash=item3445c1ba1a:g:av8AAOSwl9Jg09Qm

-I can buy a new setup from Speedway with a gear-style differential (similar to Detroit TrueTrac, I believe) for $1,069. https://www.speedwaymotors.com/Ford...ifferential-Premium-Third-Members,406880.html

-Currie sells a nice one, but it's spendy at $1700 - https://www.ebay.com/itm/264968422681?hash=item3db1594519:g:D-8AAOSwQj9eD3Pr

 

[SteveL]

If you're driving it on the street go true trak or save up for an arb. After riding in a few with Detroit I ended up just going with a spool in my 72. It was for off road but driven to and from. I just couldn't stand the clunks and pops of the Detroit. I also preferred the consistency of the spool over the Detroit on the road. Now that I want it fo more on road driving its getting an arb front and rear.

 

[bulletpruf]

If you're driving it on the street go true trak or save up for an arb. After riding in a few with Detroit I ended up just going with a spool in my 72. It was for off road but driven to and from. I just couldn't stand the clunks and pops of the Detroit. I also preferred the consistency of the spool over the Detroit on the road. Now that I want it fo more on road driving its getting an arb front and rear.

TrueTrac sounds like it would work. I have one of those in my Javelin (swapped in a 9") and my Fairlane convt already but I haven't put any miles on the Javelin and only a few on the Fairlane.

I definitely don't want a spool. As for the Detroit Locker, I hear today's versions are a bit quieter and not as grabby as an original one.

 

[Yeller]

I’ve been researching this same subject for a different project. I’ve run Detroit/grizzly lockers for a few decades, and am looking to do do another now. Me I’d buy the used nascar locker and an aftermarket carrier and Daytona pinion suport. If you decide you don’t like the locker, sell it and get your money back and install a selectable or LS of your choice. As for setting one up, no real special tools are needed but a press makes it much simpler. Use a solid spacer instead of a crush sleeve. You can reuse your existing 1310 yoke but it needs a bit of maching, it’s too long to use with the Daytona suport. Just my 2 pennies worth, maybe worth a lot may not be worth nuthin, it’s all a matter of what you find acceptable

 

[Broncobowsher]

I would go with a helical gear style limited slip for what you want. There are a half dozen different companies making them. Truetrac is made by Detroit, Torsen has been around forever (might even have invented it if I remember right) and used by OEMs (original Hummer, FX4 Ranger, Front of the Raptor, etc.) Quafi, Torque Worm, and I am sure others exist as well.

 

[msmith]

I’m in the same boat except sticking with the 3 speed and a healthy 302. I figure on rebuilding my current 3rd member myself with new gears and a True Trac.


Sent from my iPhone using Tapatalk

 

[bulletpruf]

I’m in the same boat except sticking with the 3 speed and a healthy 302. I figure on rebuilding my current 3rd member myself with new gears and a True Trac.


Sent from my iPhone using Tapatalk

Are your gears damaged? If not, I don't think I'd replace them.

 

[bulletpruf]

I’ve been researching this same subject for a different project. I’ve run Detroit/grizzly lockers for a few decades, and am looking to do do another now. Me I’d buy the used nascar locker and an aftermarket carrier and Daytona pinion suport. If you decide you don’t like the locker, sell it and get your money back and install a selectable or LS of your choice. As for setting one up, no real special tools are needed but a press makes it much simpler. Use a solid spacer instead of a crush sleeve. You can reuse your existing 1310 yoke but it needs a bit of maching, it’s too long to use with the Daytona suport. Just my 2 pennies worth, maybe worth a lot may not be worth nuthin, it’s all a matter of what you find acceptable

Thanks for the input. I have the rear diff apart now and giving some thought to just reassembling it and running it as is for now.

 

[Yeller]

Not sure what your set up is but I’ve found that the stock pinion support doesn’t live long with 4.88+ gears 35”+ tires and a lot of freeway driving. The bearing at the pinion just doesn’t like the rpm and load. Now if you don’t drive more than 55 and mileage is low probably never be an issue. Also the stock carriers are bad about breaking and spitting the pinion out on the ground with high loads put on it. But I do tend to hang with a pretty abusive bunch.

 

[bulletpruf]

Not sure what your set up is but I’ve found that the stock pinion support doesn’t live long with 4.88+ gears 35”+ tires and a lot of freeway driving. The bearing at the pinion just doesn’t like the rpm and load. Now if you don’t drive more than 55 and mileage is low probably never be an issue. Also the stock carriers are bad about breaking and spitting the pinion out on the ground with high loads put on it. But I do tend to hang with a pretty abusive bunch.

It's a higher mileage '69 that was a hunting truck, so it's already seen some abuse and neglect. Has 3.50 gears, stock 3 sp manual, 302 right now, but going to a 347 and NP435. Tires are 32's; I doubt I'll ever go bigger than 33's.

thanks for the input.

 

[EB70]

I've ran various Tru Tracs in vehicles. I like them for your type of application.

 

[Timmy390]

Tru Trac for sure....No special oil, no clutches to wear out and works great.

Tim

 

[msmith]

Are your gears damaged? If not, I don't think I'd replace them.

I have to. I had the front re geared to 4.10 and the rear is still 3.50. Going to run 33" tires or maaaaybeee 35s, but probably 33s.

 

[bulletpruf]

Ok. Don’t have a choice there.