Need the pro's advice!

Runner71 · Apr 3, 2020

So here's the thing.
Wanna swap my 3.23 for a 3.91 ring gear on my 440 4spd 489 8 3/4 house.

Do i rebuild my flawless and silent operating 3.23 in the 89 or do i go for a already rebuild 89 house with a new Eaton Truetrac 3.91 that i have available.

Ive read some good and bad about the Ttrac so im confused of what i would do.

Mainly street driven, alot off burnouts andsome 1/4mile runs is how i use the car!

khryslerkid · Apr 3, 2020

You would have to evaluate the condition of the unit you have, bearings, clutches if its not a cone, then the cost of the new ring and pinion, bearings, clutches. Are you able to set one up yourself?

Compare this to the cost of a new unit. With a new unit you'll have a second unit to swap out when you want to or sell it to make up the cost of a new unit.

I'm not sure about the True Tracks. You could ask Cass at Dr Diff

threewood · Apr 3, 2020

I have the Eaton in both my B Bodies. Never an issue with them and would buy them again.

So if you have one, use it!

1 Wild R/T · Apr 3, 2020

I'm a big fan of always having a 3.23 in reserve... It's a great compromise gear.... Not the perfect freeway gear but pretty good, certainly not the best hotrod gear but it works Okay... Keep it....

Fran Blacker · Apr 3, 2020

If you do much driving above 105kmh (65mph) it will get old fast. Your young maybe you can live with it?

JimCoronette · Apr 3, 2020

I would shelve the 3.23 and go with the TrueTrac.

Runner71 · Apr 3, 2020

Okay, it's not the 3.91 thats confusing me. Its the Eaton Truetrac iv'e read some threads about.
Seen that Dr.driff stopped selling them and some think the Sure grip feels and move the car much better then the Truetrac, that's whats making me thinking if should re-gear the Sure grip or not, And its a Clutch not a cone diff.

justcruisin · Apr 3, 2020

I see Dr Diff is out of stock on his own helical gear (sure-trac), has he sold out or stopped selling them?

PRHeads · Apr 3, 2020

Personally, I’d leave the quiet running 3.23 alone, and build up a separate complete unit for the new gears.

Runner71 · Apr 3, 2020

PRHeads said:
Personally, I’d leave the quiet running 3.23 alone, and build up a separate complete unit for the new gears.

Ive been told so by others. But will the TrueTrac live up to the Sure grip?
I like 3.23 but i wanna try the 3.91 and have som fun with it

1 Wild R/T · Apr 3, 2020

Runner71 said:
Ive been told so by others. But will the TrueTrac live up to the Sure grip?
I like 3.23 but i wanna try the 3.91 and have som fun with it

Why not go with a new clutch type sure grip?

FWIW when I ran 3:91's tires did seem to last very long... So adjust your budget accordingly...

Runner71 · Apr 3, 2020

1 Wild R/T said:
Why not go with a new clutch type sure grip?

FWIW when I ran 3:91's tires did seem to last very long... So adjust your budget accordingly...

Well, the season is almost here and the 489 with the TrueTrac in is complete to bolt on. If im going for something else i need parts from the states and with virus and so on u never know when its gonna be shipped.

But i rather wait for a proper rebuild then put in something that dont live up to the task. Just looking for a good diff thats lock as or better then the sure grip.

threewood · Apr 3, 2020

Runner71 said:
Ive been told so by others. But will the TrueTrac live up to the Sure grip?
I like 3.23 but i wanna try the 3.91 and have som fun with it

I went from a clutch type that was grabby and noisy to a Trutrac. Well worth the money. Lays 2 nice rubber stripes and quiet in the turns. No friction modifier needed. Mine is a 3.55 in the GTX and 3.23 in my 62 Ply.

Runner71 · Apr 3, 2020

threewood said:
I went from a clutch type that was grabby and noisy to a Trutrac. Well worth the money. Lays 2 nice rubber stripes and quiet in the turns. No friction modifier needed. Mine is a 3.55 in the GTX and 3.23 in my 62 Ply.

But will the Ttrac still diff if i accel in a corner and start putting som stripes or will it focus on just one wheel?

threewood · Apr 3, 2020

Runner71 said:
But will the Ttrac still diff if i accel in a corner and start putting som stripes or will it focus on just one wheel?

That I cannot say for sure because I haven't tried it.

Runner71 · Apr 3, 2020

That whats make me tought full, id like me some burnouts and have some fun time to time :steering:

and no one leggers!

1 Wild R/T · Apr 3, 2020

Runner71 said:
Well, the season is almost here and the 489 with the TrueTrac in is complete to bolt on. If im going for something else i need parts from the states and with virus and so on u never know when its gonna be shipped.

But i rather wait for a proper rebuild then put in something that dont live up to the task. Just looking for a good diff thats lock as or better then the sure grip.

Yup, I see your point... I missed your location, usually I catch it, this time I didn't... Local parts are always a benefit & right now much more so.....

beanhead · Apr 3, 2020

Runner71 said:
But will the Ttrac still diff if i accel in a corner and start putting som stripes or will it focus on just one wheel?

With the true-trac, if your in a turn and you throttle it, you'll screetch the tires and pitch the *** end right around, if that's what you're asking. It doesn't matter where you are in a turn if you give it enough gas, both tires will turn. I do it all the time with my kids in the car, they love it (always under control of course

)...I've found the true-trac to be just a better all-around performer, although you should have the Auburn cone-style in your 489 and I can only compare to the clutch-style diffs (that I've broken lol).

Runner71 · Apr 3, 2020

hmm okay. So do i go for the Eaton or the rebuild? All i want is to burn some rubber and some 1/4 miles or redlight pushes :nutkick:

Feel like the TrueTrac is more a "less of a wheel spinner" suitable for offroad. but could be wrong thats why im asking in here. want something similiar to what i have, works great just want to try the 3.91 out!

khryslerkid · Apr 3, 2020

If you have a 3.91 all set up, drop it in and try it out. I understand it's a True Trac. Just drop it in and if you don't like it no money lost. Right?

Hard to get a straight answer around here sometimes.

Need the pro's advice!

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