Rear springs- WHY _so_ wimpy?

With a smaller ring you have smaller contact area = more concentrated pressure = more heat buildup. Aside from that every revolution of the ring spreads that load over a greater number of teeth. Thousands of these rear diffs HAVE had problems. Spun bearings, lost pinion settings, and other issues. It's old news. ECGS and other builders in the know do several things to try and prevent the problems from recurring.

As far as you not having problems, well, how would you know?? You don't know how hot your oil gets or how close you have come to cooking it. It hasn't left you walking yet, but you really don't know what the condition is in there. These things can be wounded and run for a long way.

Typically manufacturers specify differentials that are rated for the horsepower of the vehicle. If you stay within the tow rating and GVW you should not have to worry about differential temperature. The whole point is that Toyota put a differential in this truck that is way underrated for the HP. That is why it's an issue worth watching.

Bigger things to worry about? Sure, who said otherwise? A $50 gauge could save a couple thousands dollars worth of damage so why not? All it takes is a tapped hole and bit of wire.

"drive fast and take chances"?? How about drive prudently and well informed ?

 

A little history for anyone playing the home game:

Toyota originally developed the 8" rear end in 1979 to go behind a drivetrain powered by the 22R engine, which at the time produced about ~100 horsepower and ~130lb ft (not exact numbers, I can't remember them, but they're within 10 or so).

This was also underneath a mini-truck weighing around 3000 pounds and sporting, if I recall correctly, 29 inch tires.

The 8" rear was, to put it mildly, extreme overkill for this application. You could wail on the thing all day long, but those tires and motor simply could not produce enough force to cause a differential failure.

This is how Toyota used to engineer things.

So, the years go by, and the Toyota truck becomes the pre-taco, then the 1st gen, and now our current second gen trucks. But the rear differential has stayed the same, outside of better machining processes. The basic specs are still the same.

Only now, it's under a truck weighing 4000 to 4500lbs, with a motor pushing ~240hp and 280tq (using premium gas). Also, 31in tires from factory. That's quite a bit more cowbell.

My guess is that Toyota engineers looked at the specs of the 8", talked to marketing about what percentage of their customers put their trucks through "harsh condition use", and then had a talk with management. Management decided that there was enough margin of error in the differential specs, and few enough customers used their trucks for hard work, that the warranty cost to Toyota would be less than the cost of R + D for a new rear end that would prevent those problems.

So they went with the 8" and called it a day.

Unfortunately.

 

Actually some Canadian members here have got tsb springs done on their pre 07 Canadian trucks , but the TSB only applies during your original 3 year , 60 000 km warranty

 

I'd say that sums it nicely. Most of the people who own these trucks won't push them hard enough to reach a failure. Even then most likely it will be beyond warrantee. The engine absolutely produces enough power to cook the differential while staying well within the rated loads. You can accept it, deal with it, ignore it, or whatever you want, but it doesn't change the fact.

 

Toyota 1 ton axle (under things like 6,000# motor homes) was a 8" ring gear granted not much power but a lot of stress far more so then any pickup my old 97 8" ring gear beat like a dead horse for 248K miles same old tiny gears. Due to the mass yes a larger crown wheel and pinion will run slightly cooler and yes a larger gear will have a bit more depth to it but unless you thrash your truck an 8" gear set will last as long as the truck. By the way I think the older rears were 7.5". So what is the percentage of failures 2%? And mostly lockers, strange. Is pulling a 3500# camper 75 hard enough? If you are going off road and run 35's and try to see just how much you can get away with before some thing brakes you need bigger gears but that is not what the truck was made for.

 

Ford Ranger:

When they introduced their version of the 4.0 V6 they upgraded their rear axle from 7.5 to 8.8 even though it has:
12% less HP than Tacoma
10% less Torque than Tacoma
11% less towing capacity than Tacoma.

By Ford's calculations that would put the proper ring size for the Tacoma at around 9".............. Must be a math error ....What were they thinking??

Perhaps a letter to Ford would straighten out their mistake.

I'm sure they would be glad to save the money.

Damn fools

 

One Word.....Japanese. They think small, efficient and well small....

I did just see in the parking lot at work, a Nissan with a cargo tie down rail system like ours, however it was solid metal and for holding down more then a empty card board box.....Looked real nice....but you can have the rest of that truck!!

 

I bought a set of the EZ-550 springs (http://www.hellwigproducts.com/products/load-control/medium-duty-helper-springs/) $80, easy install. Toyota was going to give me $500 towards the TSB up-grade which would have left me paying the $1500 balance. Since I rarely haul more than 500lbs, this was the best solution for me.

Ray

 

Perhaps you need to buy one that way you would not have to worry about trashing your final drive.

 

Ray,

I can only hope for an offer like that from Toyota. I have estimates from two local spring shops to install a custom made add-a-leaf and alignment for $300. I would prefer that to Toyotas 4 leaf pack.

 

Could easily say that in reverse regarding many of the Ranger's faults.

Let's keep this honest: The Ranger has a lot of problems, but the rear differential isn't one of them. The Tacoma has a few problems. The rear diff is one. That's all I think we're gettin' at here.

 

Take one 9" Ford (Yeah that 9 incher) rear end, slide it under anything and it is good for 750 horsepower. That should do it.

 

Yeah, hell I don't want a Ranger, LOL. My point was (is) that Ford recognized the need for bigger gears. I like my truck, I'm just realistic about it's faults. End of story

 

x2.

 

FWIW, the local independent Toyota guy tells me that the reason Toyota no longer makes motorhome chassis is because they got sick of warranty claims for rear axles. It's not that they under speced the axle for the GVW of the chasiss, it's because companies like Winnebago were putting more weight on them than Toyota intended. They were exceeding the GVW of the chassis before they were even loaded down for a trip.

 

It was because the coach makers were buying rolling chassis from Toyota with 1/2 ton 5 bolt rears under them and then adding the body weight they even went as far as to weld two wheels together to make it look stronger and that made it even worse. The axles were breaking right at the hubs it was not a ring gear issue so not only did they lose the wheels they lost the brake drum too. Toyota covered the rears from 86 back all though it was no fault of theirs and supplied full floating 1 ton assemblies and at that point they refused to sell rolling chassis to any one. The last ones were sold to U Haul with one ton rears. I had one (with the one ton rear) great little motor home but with a 22RE it was the slowest thing I have ever owned!

 

I regress.

The toyota land cruiser truck has 11 leaf springs!!! find mostly in middle east..

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LAND CRUISER PICK UP, STD, 2 DOORS, DIESEL,
AC,HZ, (4.2L), 4164cc, 6 CYLINDER IN LINE, OHC,135/3800,29.6/2200,
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This is correct. They later went to a full floating design to retain the axle. It was not a ring gear issue, it was shear weight on insufficient bearing and axle housing design. The ring gears lived because the 22RE could never come close to producing enough HP to burn them up. The problem arises when an unstoppable force meets and unmovable object and the parts caught in the middle are too small.