365 5th Gear Indent & Plunger

[Dilkris]

During the disassembly/inspection/reassembly process on the 365 Gearbox you will recall that I went on a journey regarding the sourcing of the 2 taper roller bearings for the differential; the "journey" is on this forum.
The transaxle is now back together, (I do not like to have things disassembled for long periods of time as I "forget stuff"), but there are 2 issues with the unit which I am uncomfortable about - I address just one of them here.

Upon removing the 5th gear housing I noticed that the detent plunger for the 5th Gear was not there, (the external plug was, but there was no spring or plunger, items 23 and 24) - please refer photo and parts page. Neither was it floating around in the gearbox.
My question is, (and perhaps a stupid one), should it be there and if so, what does the Lotus external 'Heath Robinson' indent arrangement do? (item 26) - or does the latter make the original Renault indent redundant?
 
Finally, the million dollar question, if the plunger and spring, (items 23 and 24), should be there, where can I get them? (Anybody got a redundant/destroyed 365 in pieces?  )
   
Obviously they can be fitted with the box assembled, which is why I pressed ahead and put the whole unit together.         
 

     

[jbcollier]

I've not worked on a 365 but the parts diagram shows that the 5th gear detent should be in place.  Why they need another one as well, I have no idea.  I'm running a 395 and the stock, internal detent works well albeit I have a low-inertia cable shifter.  Wait for someone who has worked on a 365 to comment before getting too worried.

There are a number of 365s out there bad 5th gears that may be able to supply parts.

[HelpMyLotus]

I purchased a complete 365 from Grumblebuns on this forum. In the transaction was a return of my detonated 365.  You should contact him if you need diagnostic or parts.

[Kendo]

The 365 didn't come with the internal 5th gear detent ball and spring. But a member here, from Denmark I think, has a few he sourced and is selling.

[Dilkris]

The 365 didn't come with the internal 5th gear detent ball and spring.

So the spring and plunger are not missing - they are just not fitted on this application?     

[buzzer]

As far as I can remember it is not there and relies on the external reverse 5th gear cam and ball set up. If it there engaging 5th might be rather difficult

[Dilkris]

It seems the consensus of opinion is that it is removed and effectively replaced by the "Lotus" external cam plate arrangement; in conjunction with comments received from members I also contacted Steve at SJSports (UK) who feels that the above conclusion is in all probability correct. So I am missing nothing it seems - which is good news (I think).
 
However, it begs the question, "Why is it removed and why do Lotus modify the selector shaft into the gearbox to allow for the fitting of their external cam plate which locates 5th gear and reverse?" 

In my earlier ignorance I was of the impression that the 5th gear on the 365 gearbox was a 100% "Lotus" addition - which explained the "crude" adapter plate on the rear of the gearbox which permitted the installation of the 5th gear casing and internals. This however is not the case as Renault made the 365 gearbox (with 5th gear) and fitted it to their Renault 15 and 17 cars (1972-1979). I know this as I managed to find a copy of the Renault 15 & 17 Haynes manual on ebay. The adapter plate for the 5th gear casing prevails. 

What Lotus did to this box, (please correct me if I am mistaken here) was change some of the gear ratios with Hewland manufactured components AND added their external cam plate for reverse and 5th gear.

So now we are back to square one. As the 365 box existed in original 5 speed form, why was the original 5th speed internal plunger and spring removed and replaced with the Lotus external cam plate.       

[jbcollier]

The original 5th gear ratio was 0.93 (or 0.91, would have to look it up).  Using it as supplied would mean that the 5spd equipped cars (3.78 final drive) would be slower than the 4spd equipped cars (3.56 final drive).  So Lotus had Hewland make up a 0.86 5th.  In the Renault application, the 365 has 5 nice spaced gears.  The Lotus 365 is a 4spd with an OD 5th.  That explains the ratio change.

I can only speculate on why the 5th gear detent was dropped.  If they had to make a detent for reverse, why not make it for 5th as well?

Myself?  I would refit the Renault detent spring and plunger and make up a reverse lock out at the shifter.  Side to side gives you either the 1-2 rail or the 3-4 rail.  Push through the detent to 5th.  Work through the lock out for reverse.  I did this with my 395 and shifting is problem free and intuitive.

[Dilkris]

I can only speculate on why the 5th gear detent was dropped.  If they had to make a detent for reverse, why not make it for 5th as well?
Myself?  I would refit the Renault detent spring and plunger and make up a reverse lock out at the shifter.  Side to side gives you either the 1-2 rail or the 3-4 rail.  Push through the detent to 5th.  Work through the lock out for reverse.  I did this with my 395 and shifting is problem free and intuitive.

 I agree John - fortunately as the Renault detent plunger and spring can be fitted without disassembling the 5th gear casing I can try it "in or out" - I just have to locate the 2 parts first.... (spring and plunger).

I like the reverse lock out idea but for me I see this as a stand alone project for when the car is back together.     

[Hachille]

It is a good idea to use the location for a reverse lock. I also tried with an electrical system on an NG3. But the lifespan was very limited. Electromagnet problem
https://www.youtube.com/watch?v=A5_IgWX299g

[jbcollier]

Here's a short video of the mock up of my reverse lock out:

https://jbcollier.smugmug.com/Lotus-Europa/i-4qr8BZx/A

Here's the finished piece:



Very simple to make.  The shift boot is the "spring" to lift the lock out tube up:

[Hachille]

Yes it is a good solution.

[Kendo]

I looked through my old messages. I got the reverse detent ball and spring from member Peter Boedker (pboedker). I also got his reverse lockout kit. At the time he said he had a few left. So you might contact him.

[Dilkris]

I looked through my old messages. I got the reverse detent ball and spring from member Peter Boedker (pboedker). I also got his reverse lockout kit. At the time he said he had a few left. So you might contact him.

Thankyou Kendo - just to be clear I am looking for the 5th gear indent INSIDE the 5th gear housing and it consists of a plunger and spring. (The external Lotus indent system is the one with the ball and spring - I have that assembly.)     

[jbcollier]

I think your best bet is to find someone with a Renault 365 and get them to measure up the plunger and spring.  Should be simple to have a plunger made if you have the dimensions.