TCS Detent Cam Questions

[Dilkris]

Regarding the size of the "O" ring, was the "overdrive" 5th gear made by Renault or for Lotus? Thereby might define whether it's English or metric.

I have the Haynes manual for the Renault 15 & 17 and the 5th gear "arrangement" is shown and described as the "early type 365 rear cover and rocking lever", which suggests the "O" ring in question will be metric. 
I believe, although I am prepared to be corrected, that for the Europa TCS, the 5th gear itself was made by Hewland, (a British Company), to a design specified by Lotus.   

[4129R]

"Footer", Many thanks for your kind offer, but I'm sure I'll be able to find something that will do the job.

Re the ball, How can it be in a position not central to the plate?

The aluminium block in which the ball moves may not be positioned correctly. That happened to me.

[jbcollier]

The Renault 365 transaxle came with 0.93 fifth gear and a 3.7x final drive.  The 336 transaxle had a 3.5x final drive.  A straight switch to the Renault 365 would have meant that the five speed Europa Special would have been slower than the four speed version.  So, Lotus had Hewland make up a special 0.85 fifth gear.  At the same time, also removed the fifth gear detent and came up with their external detent system.  Perhaps they were concerned the extra mass of the Europa shifting system would make the stock detent ineffective.  Regardless, the weird double-pivot, linkage was Renault, not Lotus.  Rear covers are the same.

I do not like the 365 shift mech: too exposed and more wear/leak points.  When I finally get around to my 395/352/365 franken transaxle, it will have a 395 rear cover and shift mech.

[4129R]

Regardless, the weird double-pivot, linkage was Renault, not Lotus. 

What do you mean by the double-pivot linkage?

Do you mean the rods going from the gear lever, with the UJ by the exhaust manifold, and then attaching to the gear selector rods with a roll pin, or do you mean the spring loaded 1/2" ballbearing onto the indented plate/cam which prevents over rotation when selecting reverse and 5th gears? 

[TCs Euro]

So to jump on your thread. I fitted a new o ring to the double pivot selector assembly that the lotus dedent mech attaches to, it made no difference to the amount of oil coming out... so it must be worn... there is a fair amount of play in it.
Have you guys rebushed this area and stayed with the o ring, or fitted a seal similar to the sector shaft below it.... I hope that makes sense.....

[Dilkris]

So to jump on your thread. I fitted a new o ring to the double pivot selector assembly that the lotus dedent mech attaches to, it made no difference to the amount of oil coming out... so it must be worn... there is a fair amount of play in it.
Have you guys rebushed this area and stayed with the o ring, or fitted a seal similar to the sector shaft below it.... I hope that makes sense.....

You comment makes perfect sense.
I too have an oil leak from this area and looking and feeling the lateral play, (which can clearly be seen once the spring loaded ball arrangement is removed from the cam plate) I just know that changing the "O" ring will not solve the problem and that sleeving the housing will be required.
(Note: I sleeved the housing plus new oil seal for the gear change at the time of rebuild and "assumed that the "O" ring in this shaft would be ok......it isn't )
I have yet to remove the 365 rear casing to see if the casting has sufficient material to be machined in order to support the fitment of an oil seal - sure sleeving will be possible, but an oil seal (which would be ideal) I don't as yet know.
I'll post when I do. 
Unless somebody already knows. 

[TCs Euro]

Thanks Dilkris.
I have fitted a new gear selector shaft ( which was worn) and seal, it's worked perfectly.
I have removed lotus dedent mech, spring and ball and the bit with the ears. Fitted the renault 5th gear internal spring and plunger, and a sleeve and guide on the gear lever in the cabin. 1st n 2nd have never been so precise or easy to change gear.
I am going to remove rear cover hopefully this weekend, and get a local machinist to give me his appraisal, keep you posted.
I too use a heavy grease to keep things located upon reassembly.

[4129R]

I thought the cam only moved when the gear stick was moved side to side, and only depressed the ball bearing at the extremes, i.e. reverse and 5th. 

The change 1st to 2nd, should not involve any movement of that cam.

[jbcollier]

You can see the double pivot in this parts diagram:

http://www.lotus-europa.com/manuals/tcparts/f/FL.gif

[TCs Euro]

As I understand it. The lotus designed dedent lobcam has 4 positions:
Reverse. With an ear on it
1/2
3/4
5. With an ear on it
All with fairly minimal movement between each of the 4 positions

Mine leaks oil out from here. I think this shaft and bore isnt man enough to cope with the wear / excessive strain the eared lobe puts on this area.

[Dilkris]

"Yes" - TCs Euro - your understanding is correct.
Please see attached photo's of the original early type 365 gearbox, showing the rear assembly and that of the rocking lever, (these are from the Haynes Manual for the Renault 15 and 17.)
I personally agree that the action of "Lotus" cam plate, ball and spring, accelerates wear between the rocking shaft and housing as originally, if you look at the photo, it was never designed to accept a lateral load,
The reason for this "add on" cam plate being there is interesting and has been discussed at length on this forum by some very knowledgeable people; my understanding of it is as follows:- 
In its original application the 365 box in the Renault car had a reverse gear detent arrangement beneath the gear lever.
The 5th gear "detent" was a ball and spring within the rear housing of the transaxle - lotus removed this, (why I don't know....), and replaced it with the external "Lotus" cam plate arrangement which doubled up as the reverse and 5th gear detent.
Many many 365 TCS owners have removed the "Lotus" cam plate, replaced the Renault 5th gear ball and spring detent (which can be fitted without disassembling the gearbox) and then created a reverse gear "lock out" arrangement on the gear lever within the cab - reporting good results there after.   
Personally I am going to reinstate the Renault 5th gear ball and spring detent, then remove the "ear" on the cam plate for the 5th gear thereby using the cam plate as a reverse gear detent only - my thinking is that reverse gear will be used infinitely less than 5th, reducing considerably the lateral load on the rocker shaft.
Well, that's the plan, after I have sorted the rocking shaft oil leak....