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Two totally lame gearbox wiring questions

tdskip

Yoda
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On the TR4a;

1) This very early crash box (possible from a TR3A even) has a different style connector that the later cars. Can it be replaced with a later sensor?

DSCN4909.jpg


2) One this gearbox there are two sensors, is the front one or the back one the reverse sensor?

Thanks!
 

DNK

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Tom, CAN'T ya show us a clean pic. Can't tell where the crud ends and the switch starts :jester:
 

trrdster2000

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Skip, new ones will work just fine, you will just need to change to a spade connector.


Wayne
 

bgbassplyr

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Don't think either are reverse sensors. One should be for 3rd gear OD, the other for 4th.
 

TR3driver

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tdskip said:
1) This very early crash box (possible from a TR3A even) has a different style connector that the later cars. Can it be replaced with a later sensor?
Yes, from a 3A before 1960. Yes, later switch will work fine, just add suitable terminals to the wire.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]2) One this gearbox there are two sensors, is the front one or the back one the reverse sensor?[/QUOTE]Neither one, they are both for the OD. One will close when in either 3rd or 4th; the other closes when in 2nd. Switches are wired in parallel, so OD is available in 2nd, 3rd or 4th.

Note that the book talks about the washers under the switch being important to 'time' the OD engagement. Not sure how important it actually is, but why take a chance?
 

TR3driver

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One point I had forgotten, the later switches are kind of tall compared to the early ones. I didn't actually measure the clearance, but I bent the tabs down to be sure the wires didn't rub against the tunnel.

DSCF0023.jpg
 

TR3driver

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Another thing that might clarify; these are basically "normally open" switches, they only close when the tab on the back of the shift fork depresses the plunger in the switch. Here's a photo from Nelson's article on the Buckeye Triumphs site:

Fork1.jpg
 

TonyPanchot

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Where is the switch location for the reverse lamps ?
When I had my trans swapped I lost the use of the reverse
and was told there was no place to make the connection
 

TR3driver

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TonyPanchot said:
Where is the switch location for the reverse lamps ?
It depends, it was in different locations for different years; and some simply did not have a place for it. In Geo's photo above, you can see the blank spot where the reverse switch would be, if that cover were drilled & tapped for a reverse switch. But some later covers had it on top near the shift lever, and some had it on the LH side.

You can see some of the variations at
https://www.zeni.net/trf/TR6bluebook/82.php
 

TR3driver

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Don Elliott said:
There is no switch for the back-up lights on the TR3A because there are no back-up lights.
A "reversing lamp" was listed as a factory option (tho not a very popular one it seems, and possibly deleted from later option lists. And TR2-early TR3 did have the reverse switch hole drilled, tapped and capped with a brass plug.
 
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tdskip

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Hi guys - one more totally lame wiring question.

When wiring together the switches does it matter which terminal I string together with the yellow wiring? Or, does it only matter that current can flow through them - thus making it unimportant which terminals are connected provided there is a good ground and "up stream" connections?

Where did you connect your grounds from the ground too? Just a local ground hear the transmission or on the transmission itself?

Thanks!
 

TR3driver

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Doesn't matter which terminal is which. The book says to use one of the top cover bolts for the ground, but it doesn't really matter. If you look at my photo above, you can see where the harness is tie-wrapped to the ring terminal I used for the ground.

Don't forget that the two switches are wired in parallel, meaning you need two ground wires (one for each switch).
 
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tdskip

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TR3driver said:
Don't forget that the two switches are wired in parallel, meaning you need two ground wires (one for each switch).

The wiring diagrams appear to show the grounds connected between the switches, and then a ground to transmission or body coming from the second switch? Randall, are you saying each switch should have a separate ground?

Thanks!
 

TR3driver

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tdskip said:
The wiring diagrams appear to show the grounds connected between the switches, and then a ground to transmission or body coming from the second switch? Randall, are you saying each switch should have a separate ground?
Sorry for the confusion, Tom. Either way will work fine; the ground for one switch can either be daisy-chained to the other switch (as the book shows) or wired directly to ground.
 
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