Allison filter change CAUTION

[davecampbell]

I just changed a MH3000 fluid/filter and was careful to clean the bolt and case threads as a good mechanic should. It makes inaccurate or uneven torque to reinstall dirty threads.

Since the bolts had a red tape threadlocker, I decided to use Loctite 242 to replace it, but the problem is that liquid threadlockers also reduce FRICTION so LESS torque is required to reinstall the same bolts.

Be careful using liquid threadlockers and then torquing the bolts to the same torque, i did and felt the threads start to deform at about 30 ft-lbs. Deform means "damaged"

The bolts felt tight at a bit over 20 ft-lbs.

The catch is that when the threads are dry, part of the torque is used to overcome the thread friction, and that torque isnt used to tension the bolt.

Realize these are steel bolts in an ALUMINUM case...

Bolt torque is calculated by thread pitch, material type and coefficient of friction, so dry threads and wet threads have much different torque specs.

[Chuck 1935]

My 3000 did not have any thread locker on it from the factory. I would be VERY hesitant using any type of thread locker on a part that you have to romove for service. You never use thread locker on your oil pan drain plug.

[Midniteoyl]

I'm wondering if the threads were oversized by the chasing...? Never had to reduce the torque used whan using threadlocker, teflon tape, anti-seize, etc...

Not sure about the Allison, but all the pans I have ever dropped where tightened to 12-18lbft.

[davecampbell]

Quote:

Originally Posted by Chuck 1935 My 3000 did not have any thread locker on it from the factory. I would be VERY hesitant using any type of thread locker on a part that you have to romove for service. You never use thread locker on your oil pan drain plug.

1.) what your particular trans had or didnt have does not establish proper procedure. Mechanics dont use threadlocker tapes as was on these bolts so that indicates a factory application.

2.) you cannot compare the oil drain plug because it is a different application. The trans
filter is under pressure as evidenced by the fact there are SIX bolts on each filter.
My vehicles have threadlocker on the oil drain pan bolt, because I know its a DISASTER if that single, most critical bolt comes loose - its INSTANT engine destruction.

3.) Thread locker is to resist loosening from vibration, it has nothing to do with service intervals.

4.) What happens when the trans bolts vibrate loose and the filter sucks air or leaks?

5.) Q. What happens when a steel bolt is tightened against an aluminum housing and electro-galvanic corrosion sets in and corodes the threads together?

A the aluminum threads gall (damaged)

[davecampbell]

Quote:

Originally Posted by Midniteoyl I'm wondering if the threads were oversized by the chasing...? Never had to reduce the torque used whan using threadlocker, teflon tape, anti-seize, etc...

Get a mechanical engineering handbook and find a GOOD thread torque chart, itll include lubricated and non-lubricated torque specs. It is a matter of engineering design, not personal preference of experience.

[Chuck 1935]

You da man Dave, Go with the Red locktite and don't forget to put some on your transmission mounting bolts. Iv'e seen way too many transmissions laying on the side of the road that have fallen out. Never can be too cautious !

[Wayne R]

Quote:

Originally Posted by Chuck 1935 You da man Dave, Go with the Red locktite and don't forget to put some on your transmission mounting bolts. Iv'e seen way too many transmissions laying on the side of the road that have fallen out. Never can be too cautious !

In all my travels and driving I have never seen a transmission laying on the side of the road.

[allisontec]

I have worked on these transmissions since they first came out in the early 90's. Have never put loctite on any bolt in this transmission,the later models do have a thread locker installed from the factory on the filter bolts.As long as you do not overtorque the bolts(some I have torqued to 35ft lbs with no problems.I have seen a lot of thread damage from installing bolts with a impact wrench(ATD has a thread repair kit for this) As far as having a concern about vibration,if your trans is vibrating enough to loosen any bolts then you must have a very serious problem.

[MaverickBBD]

TY allisontec. I think that settles it for me.

[Triker56]

I have changed the filters in my 3060 a few times. Never had any kind of tread lock on them and I never have put any on them.

So far over the 8 years I have owned it. No filter bolts have fallen out or any leaks from that area.

Every year when under it doing the greasing. I have not noticed any separation of the transmission from the engine. That may give any hint of the transmission falling out going down the road.

[mfire1339]

I had parts of my transmission laying on the road. t-10 4-speed. Long long time ago.


Mike

[Wayne R]

Quote:

Originally Posted by mfire1339 I had parts of my transmission laying on the road. t-10 4-speed. Long long time ago. Mike

But was it from loose bolts or a missed shift while hot roding?

[Chuck 1935]

Parts on the ground is never a good thing. Needed MORE locktite and less missed shifts !

[steelheadbluesman]

Quote:

Originally Posted by Chuck 1935 You da man Dave, Go with the Red locktite and don't forget to put some on your transmission mounting bolts. Iv'e seen way too many transmissions laying on the side of the road that have fallen out. Never can be too cautious !

Methinks one may stir the pot