hello forum, recently i have to rebuild my differential: ford 8". I want to put a "Truetrac", can anybody recommend a brand? ID? i have found this: - Eaton 912A616 (Gear Ratios: 3.25 +) - TT 912A580 912A616 need to change the gear ratio, mine is 2.78, my engine is a 250cin 6 inline so i dont know if that will work, because i plan to use it a lot in a highway 912A580 doesnt say anything about the gear ratio if you have some info, please let me know. thank you dario
Trutrac used to be detroit, but got bought out by Eaton Tru-trac is your best bet for something affordable that works well this is the best unit ive seen, just not sure if i;d spend all the money on an 8...rather spend on a 9in http://www.dpiracingproducts.com/products/8-platinum-track-differential-28-spline-1-2-tight.html for gear ratio 3.00 was aight when mine was a 250(enough to do peelouts and burnouts) did well on highway First link is newer version, 3,25 will still do well on hiway, not sure on casebreak for older version for ring and pinion brand check out US gears Sierra Yukon
I'm running a TrueTrac now and I like it. You have to run a 3.25:1 and numerically higher gear ratio as I remember and it uses different carrier bearings. Sounds like Detroit and Eaton are one in the same now since all the listings say Eaton/Detroit? Of note: a TrueTrac diff is a worm gear diff which generally means no slip. It's a locking diff, not limited slip. It is a little noisy in turns, worse in reverse while turning and once it locks both tires are spinning at the same rate. I have no issues with it since I am aware of what all the noises are.
Heres a note from one set on newer version NOTES: FORD 8" 28 SPLINE REAR 1978' AND OLDER REPLACES PART NUMBER 912A580 :: UNIT REQUIRES SPECIAL BEARINGS AND RACES LM102910 2 NEEDED LM102949 2 NEEDED BOBCAT COMET COUGAR FAIRLANE FALCON GRANADA MAVERICK MUSTANG TORINO ETC :: D8OZ4216A RING GEAR BOLTS IS REQUIRED IF CHANGING FROM AN OPEN TO A POSI REAR.
I have one in my Ram 1500. It is silent. Works flawlessly. Never know it is there until you need it. Then 100% traction both tires. I don't hear any noise on turns, or ever. I plan on slapping one in the maverick soon. Getting rid of the spool. I have been scoping them out for the maverick for several years, but too cheap to do it. Then when I blew out the stock limited slip on my truck (daily driver) and needed it back together quickly, I had the shop install the tru-trac. I will never use anything other than tru-trac in any other car or truck.
as far as i know their is no reason for the 8" true trac to not be able to take any gear ratio. the carrier bearings have nothing to do with what gear ratio will fit. you should have no problem installing a true trac into your current 8" regardless of the gear ratio you use. you do need the carrier bearing referred to above.
Not sure why Bryant, but Eaton application guide also says 3.25 and numerically higher for the Ford 8" True Trac (912A616)... page #6. I wonder why they make that claim... http://www.eaton.com/ecm/groups/public/@pub/@eaton/@per/documents/content/ct_128302.pdf
When I ordered mine I called the tech assistance because I wanted to keep my 3.00:1 gear. His response was that the larger pinion head on gears numerically lower than 3.25 would hit the diff. Who knows? I took his word for it and installed a 3.50
I really wouldn't call this a locking diff ..torque bias gear driven differential Gives unloaded tire power but not fully locked in turns like a spool or locker I noticed with my tru trac that on light traction situations where 1 tire is unloaded it doesn't get any power and acts like an open Better designs on the tru trac that fix this are wavetrac, s trac and platnium track Only one you can get for an 8in is the platnium track which is 700 bucks. ..but is allot beefier and has life time limited warranty Vs 30 days on trutrac I think it is.
I just would`nt run an 8in,they are not that strong.They are OK for a stock mtr,but a pumped up 302 or 289 will take them out under heavy abuse.Back in the 70s I had 1 w/ a 4.11 in it behind a pretty stout 302.One night turning about 8200rpms I grabbed 2nd & put a hole in the hogs head big enough to put your fist in,never found the pinyon gear & mangled my drive shaft.It also put a hole under the rear seat I had to fix,put a 9in in it(65 Mustang) & never looked back.
