Torque specs...

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HD48FL
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Torque specs...

#1

Post by HD48FL » Sun Mar 04, 2012 7:16 pm

I'm looking at torque specs on the main page for motor mount bolts and transmission plate nuts/bolts and have a few questions. I'm working on a '48 (motor, trans, and frame) with Colony hardware.

Is 35 ft.lbs. correct for the motor mount bolts?

Is 15 ft.lbs correct for the transmission plate nuts/bolts? Doesn't seem like a lot?

I don't see torque specs listed for the 4 nuts that hold the trans to the plate. Does anyone know what those should be torqued to as well as the 5th nut?

For the nuts that get cotter pins, what do you do when the hole doesn't line up with the slot in the nut?



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Re: Torque specs...

#2

Post by 1964FLDUO » Mon Mar 05, 2012 4:33 am

Funny you should ask this, I installed my tranny plate today and I tighten my tranny plate bolts to 35 ft lbs, that size bolt can easily handle it assuming you are using a reasonable grade fastener and the threads are good. You will probably get the following response from a lot of folks " tight is tight and too tight is broken" which is a sorry excuse for an answer if you ask me. I also tighten my motor quite a but more than that. I torque the motor to around 50 ft lbs.

For the nuts on the tranny studs I would try to keep the torque around 15-25 lbs and probably the lower end for the 5 th mount bolt.

On the castle nuts an cotter pins, if it doesnt line up turn it a little more until it does. This usually only requires a slight turn. I also use blue loctite on all fasteners.


A lot of people dont get hung up on torque specs and just tighten it until it feels "right". If you are more confortable using torque specs go for it.

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Re: Torque specs...

#3

Post by Cotten » Mon Mar 05, 2012 3:16 pm

1964FLDUO wrote: ..a lot of people dont get hung up on torque specs ....
Alas, 1964FLDUO,

There are a lot of folks out there that should.
(I recently had a fellow over-torque two carb manifold flanges to where they stuck the throttle!)

Chassis assembly is usually forgiving of torque specs, as loosening is the main concern.
Motor and transmission assembly, however, are far more critical, as often reassembly must be to the same torque as the part was torqued when machined. Overtorquing distorts critical surfaces: Metal moves.

....Cotten
PS: You had the gearbox on the plate before you installed it?

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Re: Torque specs...

#4

Post by HD48FL » Mon Mar 05, 2012 7:03 pm

Thanks guys, I'll use the torque specs I've listed. For the nuts on the trans studs I'll keep them around 25 ft.lbs.

Anyone else want to chime in on what they're using?

As far as loctite, 1964FLDUO mentioned he uses blue loctite. Anyone else recommend loctite?

Cotten: I did have the gearbox on the plate before I installed it, is that incorrect?

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Re: Torque specs...

#5

Post by 1964FLDUO » Mon Mar 05, 2012 7:03 pm

No gearbox is on the bench.

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Re: Torque specs...

#6

Post by Cotten » Mon Mar 05, 2012 7:34 pm

1964FLDUO wrote:No gearbox is on the bench.
1964FLDUO!

You might want to consider breaking the the loctite loose on the plate fasteners before it sets up real good.

....Cotten

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Re: Torque specs...

#7

Post by HD48FL » Tue Mar 06, 2012 1:32 am

Anyone else care to comment on torque for the nuts on the trans studs?

How about loctite, I didn't plan on using any for these fasteners, curious what others do?

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Re: Torque specs...

#8

Post by panhead_kicker » Tue Mar 06, 2012 3:48 am

I generally use a dab of blue locktite, unless it involves a nyloc fastener.

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Re: Torque specs...

#9

Post by 1964FLDUO » Tue Mar 06, 2012 5:06 am

Cotten, why would I want to break loose the loctite..? Gearbox isnt together yet, and will be put in the frame when its done..I can torque the studs with it in the frame. Would you advise against it?

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Re: Torque specs...

#10

Post by Cotten » Tue Mar 06, 2012 2:57 pm

1964FLDUO!

You will find it much easier to install the box if you loosely put the plate on it first, and slip both into the chassis together.

Much easier.

And HD48FL!

When a torque spec is unavailable, use your torquewrench to determine the ft/lbs where the fastener stops "creeping", and then apply that to the other fasteners to keep them even.
(This only applies to real torquewrenches, not silly "clickers", of course.)

....Cotten

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Re: Torque specs...

#11

Post by tschukojr » Tue Mar 06, 2012 3:59 pm

hate to be a nusiance, but with the torque wrench discusion, i've always wondered, about using extensions and how they effect torque readings--specifically the offset or horizontal adapters and universals to get in between cylinders and other hard to reach place's-------tony schuko

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Re: Torque specs...

#12

Post by Cotten » Tue Mar 06, 2012 4:39 pm

Tony!

A long as the adapter makes a ninety degree angle from your hand to the end of the wrench to the fastener, the reading is changed negligeably.

The search function or KB should have lots of previous discussions on the subject.

....Cotten

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Re: Torque specs...

#13

Post by HD48FL » Tue Mar 06, 2012 6:50 pm

Thanks for all the responses.

Still curious if others are using loctite for the engine and trans fasteners? Only a few mentioned they are using it. Trying to get more input here as I didn't plan on using loctite.

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Re: Torque specs...

#14

Post by Cotten » Tue Mar 06, 2012 7:54 pm

HD48FL!

Your question is a good one.

Most fasteners and assemblies that have a torque spec assume the threads are lubricated.

A common lube would defeat a threadlocking goober, as most demand clean and dry surfaces.

The question becomes:
Does using a threadlocker for lube affect the spec?

Graciously, most very high torque or precise assemblies should never be threadlocked anyway, such as headbolts.

And I learned the hard way never to threadlock a nut on a stud!

....Cotten

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Re: Torque specs...

#15

Post by George Greer » Wed Mar 07, 2012 4:40 am

In my job as a helicopter mechanic, the manual normally gives a torque for a certan fastiner.... Normally.

Now in the case where a specific torque is not called out, we have to use another manual, which has a approved standard torque chart.

I will try to see if I can scan that chart and post it here.

George

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