breaking a dana 25/27

when on the 'Con this year with the ecj5 crew,,,, I saw alot of hopping and full throttle abuse going on ,,I just shook my head and was shocked there was no breakage going on . those 25/27 shocked me ........... ask POSI he saw alot of it on Cadillac. it was awsome .

 

I've been kicking it back and forth whether to put a locker in my 25. Between the 225 (soon to be built), T18, D18, 5.38s, and a PM to nickmil, I decided against. HOWEVER, my D41 rear is locked and haven't broken it yet, so I must be doing something right.

 

Steve, you're not talking about me are you?

Don

 

its nice to hear from people with experience. it sounds like the spider gears are a weak link. Can a person still get a power loc for a 25?

 

They are out there but getting harder to find. Hermtheoverdriveguy has a kit to put a 27 powerlock in a 25 but even these are getting harder to come by. He usually has a couple though so worth checking.

 

maybe,,,,,,,,,,

 

Absolutely true. My buddy races his F-134 . It's extremely built and likely puts out say 120 HP.
He prefers open carriers up front. Runs a spool in the rear D44.
I sell him all my open differential gears for D25. He blows them up every few races.
Yes D25 and D27 Powr Loks are few, far between and never to be had for cheap.

 

Those of you who have used a lock right to replace the spider gears, do you begin breaking other parts/which ones?

 

well I have had cases with hairline cracks off the openings,
I think throwing a lock right in there would break them open .

 

I haven't! seems that the power to the wheels is divided so you dont get the torque on either axles assembly like you would otherwise. I may be wrong but it sounds logical in my mind. my wife wedding ring is stronger than those spiders

 

Actually it puts more stress on the individual components like shafts, u joints, case, etc because there is less give between the components. A powerlock still has give depending on how tight it's set up

 

i'm sure your right, but then again you dont have to put as much juice to it to get through somethin at least thats what i've seen, I can idle through stuff one legged trucks have to blast through.

 

What is the biggest tire you would use on a 25 used some on trails and some on rocks. I would say a 6.5 out of 10 with 10 being rough rock crawling?

 

The Jeep must be envisioned as a complete synchronous system.
Your question in part depends on the engine and the clutch size.
You can only dump so many foot pounds of torque onto the axle due to clutch pressure limit.

Increasing tire surface contact area (size) or decreasing air pressure both increase traction and decrease tire slip.
That overall will increase the stress on the drive train.
I believe you can get by running the biggest tire that fits your Jeep if you only have an F-134 with 8-1/2" clutch.

 

I have an 8.5 inch clutch with an amc 196 from a rambler and a t98. How does a limited slip or locker affect tire size?

 

Back to the complete synchronous system.
Think of it this way... A chain.
Anytime you install a stronger link into the chain, that strong link will not break.
Only the weakest link will break.

A limited slip, increases the stress upon the drivetrain as compared to an open differential.
A limited slip decreases the stress upon the drivetrain as compared to a locker.

For reference; the typical 8-1/2" clutch in good condition provides about 165 ft lbs of torque.
Regardless of engine specsifications. The engine cannot deliver more torque than the clutch will allow.

The T98 basically doubles the available torque as compared to a typical 3 speed transmission.
In simple terms the T98 is a double strong link in your Jeeps chain.

Increasing tire surface contact area increases drivetrain stress.
Decreasing tire pressure increases stress because traction increases.

Its already been stated the weak link in the D25/27 is usually the spiders.
Powr Lok is a fix.

 

My books show that the AMC 196 produces 150 to 185 ft lbs torque depending on the compression and carburetion.
I suspect the use of an 8-1/2" clutch is a very weak link.

 

I run 33x12.50x15 TSL swampers with 44 rear and 27 front both with lock rites and 5.38 gears. Mild built 225 with t-14 trans and d18 case. I have had great luck with this set-up but I only use as much skinny pedal as needed to make an obsticle. I like to crawl and let the tires work.

 

I have the same except with 3.73 gears works great haven't broke anything...yet.

 

That is good info. What kind of terrain?