Manual gearbox sensors - what are they for?

Geoff in Gully

Geoff in Gully

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Fellow Frogger
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I have a couple of 395-13 type gearboxes from R17 Gordini and R18, one of which is going in to my ’75 R12.
They both have three electrical senders on them. I don’t know what they’re for.

I wasn’t going to worry about them, apart from the reversing light switch, but it’s getting to me.
I don’t cope well with unanswered mysteries.
So I’m seeking help from the brains trust.

One sender is on the side, has two connectors and the trusty multimeter in conjunction with manipulation of selector suggest it’s the reverse light switch.

The second is on the top near the rear, but not on the end casing over the fifth gear. Single electrical connection (presumably opens/closes to earth on activation) and doesn’t appear to connect with anything inside. Sender is barely longer than its threads with nothing protruding into the gearbox casing. I’d have thought an oil temp sensor would be down low actually in the oil. Air temp or pressure is just nonsense, surely...

The third is on the end of the casing at the selector end covering the fifth gear. It’s near where the speedo cable attaches. Looks to be in proximity to the end of the secondary shaft. Two electrical connections. I’m thinking something to do with road speed related rotation - some sort of signal to engine electronics which both the donor vehicles would have had. Might also be primary shaft rotation to detect engagement of clutch?...

I figure someone would know the truth of these three amigos, but I‘m willing to entertain plausible offerings.
I need to get some sleep....

thanks, Geoff
 
R17G did not come here with 395 but 365 as far as I know. Does it have long or short outdrives?

The second "sender" sounds like a ground to the g'box casing, not sure what for.
 
I think one on the end housing tells it when it’s in 5th for something in the anti pollution system in some cars. Don’t need it in a r12.. I have wondered about that one on the top though as it doesn’t seem to do anything.

Good on you for getting your hands on a late 17g 395... I was pretty sure we got them in aus in ‘75 and later cars and had believed all ‘74 cars badged “17TS” had the 365 whereas most badged “17gordini” had the 395. I’m not sure when they changed exactly though.
 
I have a1974 17TS and a 1974 17 Gordini both have 365 boxes. Some very late 17 G Phase 2's had electronic ignition units. But not in Australia unless a private import made it here.
 
Really? The second version of R17 ! :confused:
I think they had the 395 boxes

39165212462_0930c65e3e_b.jpg
 
From the evidence and most here know, the 365 can fail, so it was a bit of a lemon. Great ratio's but weak. Then came the 395 to replace it in the 17 second version (maybe some 1st versions later in the 70's for AU and would love more info) and the R18 from what I've learnt so far.
 
Here we go... another 365 gearbox thread! Maybe we should revisit the last one to talk about what cars had what unless we can answer the original poster’s questions.
It’s hard for me to know what was standard when they were new, as I didn’t start working on these cars til they were 30 years old anyway! I did have some help from people in the know back then though.
End of the day, any 395 with the short output shafts, regardless of what ratio setup it has or if it came from a 17 or is an 18 one with swapped shafts is going to be a good upgrade for a R12.
 
Shoji said:
Really? The second version of R17 ! :confused:
I think they had the 395 boxes

View attachment 123889
Click to expand...

Wow, John. You sound like a real expert. I bet you can even tell the difference between a 17 block and a 16.

That version of the 17 in your picture never made it to Australia. Not from the factory, anyway. Hence my question.

Shoji said:
From the evidence and most here know, the 365 can fail, so it was a bit of a lemon. Great ratio's but weak. Then came the 395 to replace it in the 17 second version (maybe some 1st versions later in the 70's for AU and would love more info) and the R18 from what I've learnt so far.
Click to expand...

Survivor bias. Look it up.

The only lemon here is your post.

The 395 was always available in parallel with the 365 for lower spec cars. It didn't come "later". On the contrary, the 365 was an option offered on top of the range cars in the highest tune spec (17G, 12G).
Consequently, the 365 was always driven hard and/or raced and often in cars with uprated engines, so yeah. It was a performance g'box.
Like, for performance.

As opposed to the 395 used in R18 with half the power or thereabouts, meant for shopping trips.

From faint memory some version of the 395 was used in some North American R17 (not sure what version/R1318/1328 whatever that means), a car with a detuned engine again from the 120HP we got here.

They also appear with 395-08 ID in RHD cars (844 engine? - 1605cc anyway, not 1565) but I don't know what markets. Hence my curiosity. If this is indeed a genuine R17 'box, it's the first of its kind I have heard of.

European versions are another story again, I didn't consider these in my comments.

The manual (MR 185, November 1976) says 395 boxes used on R17/15 cars (with engines 844 and 843) all have suffixes of the form 0x (where x is a single digit giving numbers like say 395-08 or 395-06) so no 395-13 there. Which means it is very unlikely we have here the trace of a 395 out of a 17. More likely a swap with a 'box from a R18 by some owner in the past.
 
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The phase 2 Gordini never had fuel injection but ran a two barrel Weber down draft. Was power down?
 
The old RWD Geminis had two sensors from memory, one for the reverse light and one for some anti pollution reason in 4th and 5th gear.
When doing a clutch or main bearing everyone inadvertently connected the wrong wires so the reverse lights would come on in 4th and 5th gear after the repair. They had an electronic choke, enriching solenoid, and a fuel shut off solenoid.
Yes, a little off tangent, but as they are similar vitage it may give some ideas.

Dave
 
I think you're on the right track. If the car had antipollution stuff it may be that some device like that could be used to control the carby when cruising in fifth.
 
Gosh guys, talk about information overload!

While both boxes have ID tags with 395-13 on them, the one from the R18 has longer output shafts. 24mm or so wider between the ends of the things what the drive shafts go onto. That’s what drove the decision to use the R17G source one as I can still use the existing (new) drive shafts. fyi also, on the R17 box the drive shaft seals are mounted externally meaning you can change them without removing the diff bearing lock ring and upsetting the bearing leadings.

Given the significance of the difference between the boxes, I did have my doubts whether both were -13 versions. As they appear the same in other respects I’m happy to believe the 395 designation. I only have the word of who I got it from as to the provenance of the ‘R18’ box though given the extra width I buy the line. The R17 one was removed from an R17 personally by the person I’m getting it from - there is no doubt of its source.

But, when it comes to bits from 40 year old cars who can tell what transpired in that time to divert it from originality?
I’m with Schlitzi on that aspect

Another data point for those interested, the R17 engine had fuel injection and mechanical dizzy. The dizzy has a pair of wires extra to your typical unit. Figured they sent some signal to the ECU.

That wasn’t keeping me awake though, the past is the past and it’s the future that beckons.
I’m going to follow Angru’s thought about a 5th gear sensor and see if that provokes a signal.

But, before I go and do what I’m supposed to be doing, I see mention of difference between 16 and 17 heads. Would that be there extra ports under the inlet ports?
 
The 395 was built with both styles of outdrive seals.

Either way, you can change the felt type seals from the outside as well, it's just a pig of a job and my gut feeling is the idea behind the design is that you don't change them. You just put up with them and can wash them in situ with some solvent to flush out the crap they soak in or accumulate on the surface.

Outdrives. These are interchangeable between the long and short type. Both fit in the satellite carrier of any 'box so it is not impossible someone did exactly that, to avoid having to source the shorter driveshafts that are not as easy to come by. I was contemplating doing the same thing when I had the 395 box I was planning to use in my 17G.

That said, (and again without checking the book) it is not impossible that 395 boxes had both outdrive types depending on the application of the 'box.

Does the mechanical dizzy have points or magnetic sensor? I would imagine magnetic, because of the two extra wires you mention. This is what my 17G dizzy has, don't remember where the wires go, and without looking it up in the book I think they are used to drive the coil.
 
On a 17 d-jectronic the dizzy is mechanical. The top section is the same as a normal Bosch one (albeit a bit backwards). The lower section houses a set (or rather 2 sets) of contact points that tell the ECU where the motor is in its cycle. They tend to be fairly reliable until the distributor wears and the cams move around a bit. Each contact controls injection in 2 cylinders and the first symptom is normally that the car runs very rich on 2 cylinders.
What do you mean about the extra water port between 16 and 17 heads? Are you talking about The passages under the inlet ports of all bit number 2 cylinder? If so these are common to all r16ts and 17 tl/TS/ g motors we got in aus. Or are you talking about the port under the auxiliary air valve on a 17ts/g around where the fuel pump goes on a 17tl/16ts?
 
Transmission switch was used on USA models as part of the emmision controls.
 
Sunroof said:
Transmission switch was used on USA models as part of the emission controls.
Click to expand...
And I thought that you were going to say it was so that the American drivers could tell when they were in reverse/going backwards ...

(I can get away with saying things like this as long as my wife doesn't see them. She's American.)
 
angru said:
...What do you mean about the extra water port between 16 and 17 heads? Are you talking about The passages under the inlet ports of all bit number 2 cylinder? ...
Click to expand...

yes, though I mistakenly implied the ports were in the head rather than the manifold

Manifold.png
Head.png
 
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