Driveshaft bolts orientation (1 Viewer)

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This is a simple question and I feel asking it is weird. In my trade, aircraft maintenance, lock washers always go under the nut when it’s a nut/bolt assembly.
When I disconnected my front driveshaft the lockwashers were under the head of the bolt. I immediately thought what idiot did this. So for s***s and giggles I looked in the FSM and the pic appears to show exactly that! Am I misinterpreting the diagram or do the lock washers actually go under the head of the bolt:hmm:
I did read in another post how to replace the u-joints in your 80
That the washers do go under the head of the bolt on the diff end.
This was the only place I could find the mention of the washers for the driveshafts.

Can anybody explain why under the head of the bolt instead of the nut?

Thanks
 
Last edited:
This is a simple question and I feel asking it is weird. In my trade, aircraft maintenance, lock washers always go under the nut when it’s a nut/bolt assembly.
When I disconnected my front driveshaft the lockwashers were under the head of the bolt. I immediately thought what idiot did this. So for s***s and giggles I looked in the FSM and the pic appears to show exactly that! Am I misinterpreting the diagram or do the lock washers actually go under the head of the bolt:hmm:
I did read in another post how to replace the u-joints in your 80
That the washers do go under the head of the bolt on the diff end.

Can anybody explain why under the head of the bolt instead of the nut?

Thanks

Incorrect installation.

The drive shaft plate washers (10mm and 11mm) go under the coated flange nuts— transfer case side and differential side.
 
I’ve been working jets for 30 years and have never installed or seen a lock washer on an airplane. I don’t have an explanation for your question but I believe that the fsm refers to that washer as a “spacer”. I install my “spacers” under the nut and so far no one has died because of my deviation from the manual.

Perhaps during the factory assembly process, for speed and convenience, the bolt head is rotated with power tools to torque the fastener rather than the nut which would dictate the spacer being on the bolt head side.
 
I’ve been working jets for 30 years and have never installed or seen a lock washer on an airplane. I don’t have an explanation for your question but I believe that the fsm refers to that washer as a “spacer”. I install my “spacers” under the nut and so far no one has died because of my deviation from the manual.

Perhaps during the factory assembly process, for speed and convenience, the bolt head is rotated with power tools to torque the fastener rather than the nut which would dictate the spacer being on the bolt head side.

I work on the smaller aircraft, King Air, Twin Otters and light piston AC. Lots of lockwashers on the little guys!
I have also worked on Dash 8’s, and now that you mention it, yea, I saw very few lockwashers, never really thought about it!

Thanks gents, I will install under the nut, as that is what we don’t want falling off!
 
Am I missing something? I don’t think either of the 80’s I’ve owned ever had a lock washer in this location, only a flat washer and retention is relays on torque. Mine have never come loose between the inspections I do before and after every wheeling trip.

Are you talking split lock washer?
 
It doesnt really matter as long as the washer/"spacer" is under the part you are turning. @baldilocks is correct in regards to the factory assembly process. Just be sure to check them when you check the steering arm studs.
 
Yes, a split washer.

5D0D00B6-E7D9-41D0-9FAC-0F72C17D612F.jpeg
 
That bolt has spent its whole life in Cali!
It’s just got a gooey coating of what appears to be anti seize or lubtorque.
All my other cruisers had lockwashers :meh:


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The bolt appears to have spent some time beside on the ocean floor and that washer is not a Toyota part.
 
My 1994 fsm does show a washer in the cartoons but the text makes no mention of one.
 
My 1994 fsm does show a washer in the cartoons but the text makes no mention of one.

I also have the 1994 FSM and yes it does show a washer and my interpretation of the drawing shows the washer and bolt on one side of the vertical strobe line and the nut on the other side of the vertical strobe line. This is why I believe that means the washer goes under the bolt.

But **** it! I am going to follow standard practice which is lock washer or washer typically goes under the fastener you are torquing or turning which in this case is the nut!
 
My interpretation concurs.
 
Washer under the bolt head always at the diffs and under the nuts at the t-case for obvious reasons.

What is the reason for the washer under the bolt head instead of the nut? What you are saying is my interpretation from the FSM.
I am trying to figure why under the bolt head as it goes against what I have been told to do in my last 30 plus years of working on mechanical things.
 
They are even called spacers. 90560-10H00

Interesting as they are split washers and they even have the silver coating on them, the same coating that is on the bolt and nut.
I have often thought Toyota's description of hardware can be odd at times, but it is what it is!
 
Interesting as they are split washers and they even have the silver coating on them, the same coating that is on the bolt and nut.
I have often thought Toyota's description of hardware can be odd at times, but it is what it is!

You have incorrect parts. They should be solid. Regardless, they will work fine.

None of this is rocket science. :)
 
You have incorrect parts. They should be solid. Regardless, they will work fine.

None of this is rocket science. :)

I know its not rocket science :). It just when I see something that does not make sense I try to make sense of it :bang:, it can be a bad thing at times, lol.

I am half tempted to order some of the "spacers or plates" as they are called, but you being the parts man probably know what they really are so I will save myself that trouble:).

Thanks for the help!
 

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