TR2/3/3A checking axle float triumph tr3a

[aaronf30]

I'm switching the backplates on my drums from the 10 inch to the 9 inch and was told to check the axle float by Macy's garage (who is replacing my bearings and seals). What is this and how do you check it???

 

[TR3driver]

What you are checking is how far the axle shaft can move back and forth within the housing. There must be some clearance, but not too much, for proper operation. Since the thickness of the backing plates will affect the clearance, it is a good idea to check whenever changing components. The process is described in the workshop manual (in the "TR3 supplement" in the back).

Enco normally has a kit with a magnetic base, 1" dial indicator with .001" graduations and the rods to link them together. But their web site www.use-enco.com seems to be down at the moment. I am hesitant to recommend buying precision measuring tools from HF, but these would probably do the job:
https://www.harborfreight.com/multipositional-magnetic-base-with-fine-adjustment-5645.html
https://www.harborfreight.com/1-inch-travel-machinists-dial-indicator-623.html

 

[AEW]

I think it's called the "Thrust Button". Sits between the ends of the two axles. As Randall points out, it is supposed to be free to move evidenced by the slight in/out of the axle at the wheel. One of my necropsies was a unit that had been assembled w/o the needed space (I presume anyway) and the button had actually friction welded its self to the end of the axle. Lot of other damage after that.

 

[Geo Hahn]

FWIW -- I did mine with the Harbor Freight unit and it seems to be fine (about 7 years now).

You'll probably figure this out and likely it is the instructions somewhere but... you need both rear wheels off the ground when you do the measurement. D'oh!

The biggest bit of bother is having to source additional/different shims for any adjustment you find you need to make. I think you will also need 6 new locking tabs.

 

[aaronf30]

My manual comes on friday . ( i just got the car last saturday) is this something i have to open up the diffy to measure ? Just want to know what im in for once my manual comes.

Thanks for all the advice, ill probably just get a HF one.

 

[TR3driver]

No need to remove the cover, just the brake drums will do. You mount the dial indicator onto the back plate, with the shaft contacting the hub and more or less in line with the shaft. Push in on the hub, note the reading, then pull out and note that reading. The difference should be around .004" to .006".

https://docs.google.com/open?id=0B2H2NJt34OffYWZiN2VlZGMtNTkxMi00NGUzLWE4NzMtMGRkODRkYzU3MDU1

I just noticed that HF has a kit with a clamp & flexible mount, which I think I'm going to try. In most cases the magnetic mount works better for me; but it was a bit tricky getting it to grab the backing plate and there have been some other tasks where the flexible mount would have been an advantage. https://www.harborfreight.com/clamping-dial-indicator-93051.html

 

[Jerry]

I have doubled the shims as per the original when I took the axles off and the gap does not appear to be decreasing. I read the supplement in the back of the book but do not see why the gap is not changing. I did change the crown assembly to that of a doner car due to a broken tooth. Any ideas? I am out of extra shims
Jerry
PS both axles are in place

 

[Geo Hahn]

I have doubled the shims as per the original when I took the axles off and the gap does not appear to be decreasing...

To decrease the float (gap) do you add shims or remove them?

I honestly don't know w/o looking at some diagrams & thinking it thru -- I just seem to recall there was some aspect of this that was counter-intuitive.

 

[TR3driver]

You remove shims to decrease the end float.

Also sometimes overlooked; both axles must be installed to get a meaningful measurement.

Another thought, did your donor car have a solid axle? The IRS differential itself (not the pumpkin obviously) is identical (or at least nearly so), but lacks the block in the center that the solid axle halfshafts ride against. Without the block, the float will always be huge. ISTR it's even possible to add the block to an IRS diff (but not certain on that point offhand).

 

[Jerry]

Oh yea, dumb &&*& me, I should really read the directions better. Decreased the shims and it works just like the book and you guys said. Amazing, my reading ability. I really do better when I have my wife helping. She reads the directions, and I use the hammer. Works much better. Thanks for the wise up note.

Jerry

 

[TR3driver]

No worries, Jerry. We've all been there.

I've been working on my "high tech" starter that died after only 10 years (not so good compared to the original that made it some 50 years) the past few days. Looks like part of the problem is that the motor hangs down right next to the exhaust pipe; so I tried re-clocking to position it the other way. Drilled lots of holes, broke off a drill bit in the adapter plate, thought I had it all worked out ... until I realized that with the motor on top, the top bolt cannot be installed! Of course I didn't find that until I had all the wires connected, bottom bolt installed and so on. So I wasted 3 evenings of fiddling around for nothing.