Engine/Transmission (1994 - 1998) bolt heads coming off

[dseabaugh]

Has anyone had any trouble with the heads of the bolts that hold the ring gear to the carrier in their Dana 70's coming off? I pulled the cover on my rear differential today to change the oil and two bolt heads were laying in the bottom of the gear case. looks like they "stretched " off. There is no sign of twisting off. They also look like they have been cracked for a very long time from the coloration. I decided to pull the other 10 and one more popped off when I was turning the differential to get a good angle to break them loose. I have ordered 12 new ones from the stealer. Does anyone Know what the proper torque should be?? Torque was around 40 ft. lbs. on all of the remaining bolts which I am sure is way to low.

 

[B KIRK]

Torque should be 120 -140 ft. lbs. Was your ring gear ever removed? Any time it is unbolted you should use new bolts. They do stretch, and if reused, will give an inaccurate torque reading resulting in breakage.



Brad

 

[dseabaugh]

The truck had a new rearend put in under warranty before I owned it. According to the stealer new gear sets come with new bolts but that doesn't mean the new bolts didn't go into the dealers parts inventory instead of the truck. . I also had the rearend checked out at another dealer while it was still under warranty as the oil had turned black and I wanted to know if there was a bad bearing or something cooking the oil. They chrged me $150. and said all was just fine. I think the oil was just some cheap recycled imprt junk the dealer had bought cheap . I tore into the rearend this evening and the only thing I can find wrong is the bolt heads that haven't popped off will if you try to torque them down. Bearings, seals, gears all are fine.

 

[Joseph Donnelly]

You should have the Dana 70, 10. 5" diameter ring gear, ring gear bolt torque 120-140 ft lb.

The Dana 80 (11. 25" ring gear) takes 200-240 ft lb.

 

[B KIRK]

I thought I read that somewhere before.



Brad

 

[Speedo]

Bolt heads coming off....

It is possible that the bolts were put in with gear lube on them

and it is a good thread lube, too good in fact. Even using a torque

wrench it is possible to over tighten bolts if the spec does not call

for a thread lube and one is used. These are not stretch bolts and

it is ok to reuse them under normal circumstances but if they are

suspect it is cheap insurance to replace them. I would clean the

threads, bolts and ring gear, and use red locktite to retain them.



Gus

 

[B KIRK]

What would be normal circumstances? Have done a lot of gear swaps and never reuse the ring gear bolts because they end up breaking. A quote from my service shop manual:



"Remove and discard the ring gear bolts. They are not reusable. "



If they were overtightened, why would they only be at 40 ft. lbs. of torque as stated in post?



Brad

 

['956Wheel]

Re: Bolt heads coming off....

Originally posted by Speedo

It is possible that the bolts were put in with gear lube on them

and it is a good thread lube, too good in fact. Even using a torque

wrench it is possible to over tighten bolts if the spec does not call

for a thread lube and one is used. These are not stretch bolts and

it is ok to reuse them under normal circumstances but if they are

suspect it is cheap insurance to replace them. I would clean the

threads, bolts and ring gear, and use red locktite to retain them.



Gus

Gus,



I have been a Machinist 25+ years and have never heard of "stretch bolts", can you explain. Also, torque is properly done with mating surfaces and threads lubed so as to eliminate false reads due to variables such as friction, gauling and such. Loctite 272 (red) is permanent, 242 (blue) would be proper for this application. When torqueing bolts with Loctite, the Loctite is the "lube" if you work fast. ANY CRITICAL BOLT MUST BE REPLACED UPON REASSEMBLY. Would you re-use your hitch to frame bolts?



Mike

 

[Speedo]

Stretch bolts and thread lubes

There are applications that use bolts

that are designed to stretch past a

point of returning, they are sometimes

called stretch to yield fastners and are

a one time only use. Thread lubes like

International Compound #2 is an

extreme pressure lube and allows the

threads to turn easier than normally

allowed for and will allow bolts to come

apart under called for torque. Gear lube

is an extreme pressure lube and will let

a bolt fail at normal torque. while it is not

as effective as IC#2 it is still a lot better

than oil. Locktite compounds are often

used according to bolt size as well as

application. Red Locktite, 271, is a good

application for ring gear bolts. I'll see

if I can find some of my literature that

gives examples of some of fastner info

that you might find interesting I'll see if

I can get it posted.



Gus

 

['956Wheel]

HUH? I have never heard such nonsense in my life! If you do not replace bolts used in critical, hard service applications your kidding yourself! Bolts are graded and ALL will stretch... . go tighten one... any grade then check the threads with a go-no go gage.



On Loctite, I have been using it for years on everything from x-ray machine assembly to soil compactors (vibration type). Now I am due for a Loctite lesson?



Anti-seize compound is used on steam turbine assembly, thats my job, bolts are stretched to compensate for thermal expansion. They are B 16 (a 400 series Stainless Moly Steel) and weigh in at anywhere from 50+ lbs to 350+ lbs... . they are replaced when unstretched reads show loss of return from stretched reads. Its called thermal fatigue.



Mike



Bottom line, and back to this threads subject. The bolt failure was either due to not properly torqueing of the bolts or reuse of hardware, either way its fatigue in a high demand application. That pinion wants nothing more than to crawl up the ring gear hence "wrap". LOTS of force on them!

 

[jimk]

steam turbine

I too have helped overhaul steam turbines, not on a daily basis though. Only on a major overhaul thank goodness. Last year a company (contractor) come up to use ultra sound to heat the bolts to get the shells off the turbine, a lot faster than the old bolt heaters.

Anti-seize is used on the threads. Except for a lot more money I dont know of anyone that looks forward to a turbine overhaul.

Jimk

 

[dsldoug]

jimk & 956wheel



take it easy please



dseadough, it is an unfortunate but true that most rear ends at dealers are built using nothing but a worn out impact wrench for a torque wrench. the were under torqued and probably reused if i remember correctly the new ones from the dealer should come with locktite already on the threads, just clean and dry the holes and torque the new ones to 120-140# and all should be OK.

if you have any questions about your wrench shoot for the middle(130)



the torque to yield bolts you are referring to are used mostly in over head cam gas engines with aluminum heads for head bolts



-doug

 

[Speedo]

Bolts and such....

Without trying to make this too long I'll offer a little more info

to try to explain some things I offered earlier. First off all bolts

stretch, from the first bit of torque applied to them until they

reach Tensile Point which is failure. The first part of this road to

failure is the Elastic Range (Proof Load) this is the range of stretch

where a fastner will return to its original length. Once it stretches

to a point where it will no longer return to its original length it has

entered the Plastic Range. When the fastner reaches a point that

it stretches . 02% beyond its loaded length it has reached its

Yield Point. The next scenic spot along this road to failure is called

Tensile Strength, the point where the fastener fails to supply

tension, as we continue down this road we finally reach our final

destination called Tensile Point where the bolt breaks. Most of

the fastener industry uses 75% of proof load to apply a torque

value and within this range the fastener will return to its original

dimensions. This brings us back to the failure of the ring gear cap

screws, if these bolts had been removed and reused that alone

would not be a be a reason for failure, what I might expect to find

would be the use of an impact wrench, for the added speed to

complete a time based job, combined with a poor feel for the

wrench and the addition of an EP lubricant to the threads bringing

these cap screws to their final destination of Tensile Point. The

ones that felt loose were probably taken to their ultimate tensile

strength and as they were subjected to vibration and load the

started to lose their tension.

Now on to "stretch bolts" these are bolts that are taken into

the Plastic Range where they are stretched to a point that they

will not return to their original length. One reason for the use of

these bolts is to keep size to a minimum and still achieve a the

desired clamping force, head bolts are one area where these can

sometimes be found. Structural fasteners are another place that

one can find where fasteners are taken into the Plastic Range.

Boiler and pressure vessel fasteners have their own special ASTM

requirements because of their environment.

The latest Loctite information that I have no longer lists 271 or

242 but it shows 243 as a world wide alternative for 242 and lists

262 as red. 243 is shown for fasteners from 1/4" to 3/4" and

lists it as removable strength 262 is listed for use with fasteners

from 3/8" to 1" and is listed as permanent strength. Applications

for 262 are All fasteners that must withstand heavy shock,

vibration, or extreme environmental or chemical conditiions.

All this information is available from publications like K-133 from

Bowman Distribution and Loctite LT-2157A or numerous other

publications.

 

[dseabaugh]

Thanks guys. Sorry it took me so long to get back to you. Our youngest daughter got married in St. Louis this weekend so I've been a bit tied up. Went through ten pages before I got back to this thread. My help did not pick up the bolts Friday when they came in like he was supposed to so I guess I'll find out tomorrow if they come with thread locker on them. Have Farmed, plus own trucks and construction equipment for 20 years I've had a rule that everything goes in the shop as soon as we get it (new or used) to tighten all the bolts. I have Locktight 620 on hand but I think it is green bearing mount. Everything "WE" work on is torqued, locktighted, lockwashered or locknuted (No nylon) or welded. The bolts did not look sheared (would have been wrong place) did not appear stretched in the threads, and were not twisted, nor did they look crystalized. The bolts have been broken for quite some time as 3/4 the way through the metal was grey and last bit was shiney. Would have been a mess to have some of this come apart on a three day trip to Nebraska or Florida with a gooseneck load of fence. The holes in the carrier are larger than the bolt which is something I did not expect though they are not elongated. they are still round.