Ready to open my 365, a couple questions

[RacerX]

Greetings all, I pulled the 365 out of my '74 TCS to diagnose and hopefully solve the mystery of no reverse. the box shifts well into all 5 forward gears so my plan was to split the case and take a look. 1 question I have is do I need to remove the output shaft bearing nuts? seems to me if I'm splitting the case it should pop right off without removing the nuts. A case could be made I should replace the seals since I'm there, but I was trying to avoid resetting the preload if I can avoid it. It looks like I can pull the bellhousing, pull 5th gear and the back plate then split the case. Am I missing anything? Thanks! Mark

[jbcollier]

Yes, you can leave the finned nuts in place.  I would double check the preload and backlash upon reassembly though.

Before splitting the cases, just remove the rear housing as that's where are the shifting takes place.  Even before that, just disconnect the linkage and see if you can shift into reverse manually.  Doesn't take much play in the gear linkage and suddenly you can only set it to get reverse or 5th but not both.

[RacerX]

Thanks!
 While the box was still in the car I removed the linkage and selected all the gears by hand and confirmed 1-5 were ok, but reverse seemed to click into position as expected but no drive. I'll remove the rear cover and start the investigation there, then remove the bellhousing and see if I can get a borescope in somehow. Will report back.
 On a positive note: when we removed the gearbox we found an aluminum flywheel and a like new clutch!
-Mark

[Lotuswins]

Hi Mark,

Be sure you follow the manual on removing the rear case, i.e. make sure its in the right gear before removing it.  If not you'll have to split the case to find the little ball bearing that will drop out inside.....ask me how I know.  Also, if you don't remove the nuts, you should remove the splined spacers on the axles before you put the cases back together to keep from damaging the axle seals.

The shifting into reverse is weak with the long linkage and on mine it happens in two distinct movements and is difficult.  First movement is the detent and the internal arm and pivot moving, then the straight cut gears will hit, often right on top of each other so it won't go into gear so you have to try again after shifting into another gear to get things to shift a small fraction so the gears will eventually slide into place.  On the bench it will be harder since you have no leverage to speak of.  I say this because these boxes are really robust and it is rare to find internal problems.  My first one went 130k miles and it was eventually needing bearings but was still shifting fine. 

Jerry Rude
4005R

[Footer]

Before removing and splitting the case, take 15 or 20 minutes and inspect the linkage movement at the rear of the case.
In the parts manual, #26, the Cam Reverse Indent  and #29, the Housing Reverse Indent are not in a fixed position and if out of line, can negate some gear selections.  These need to be removed for clearance in order to remove the motor/transaxles and may not have been returned to the same position.  When I took my motor out, it got moved and would not let me find 1st and 2nd gears.  By loosening two mounting bolts on #29, the Housing Reverse Indent, it can be rotated.  I rotated  it about ten degrees clockwise and 1st and 2nd were returned, almost like a miracle.
At the ends of the travel, Reverse an 5th gears are selected and perhaps you can return reverse with this adjustment.  Mine only needed slight movement, about ten degrees as I said.
If this doesn't resolve the problem you can always take out the transaxle.  Good Luck and let us know what you come up with.

https://www.youtube.com/watch?v=aUO5YvgX9o8
This is a video showing the motion of the two parts.

[RacerX]

Weekend Update,
 First thanks to "Lotuswins" I did follow the manual to remove the reverse detent plunger and spring only to find it was already gone (I believe they were removed when Lotus installed the external 5th/reverse detent mech). So I moved on to removing the 5th gear detent spring and ball. This was NOT mentioned in the manual, but great advice. Also thanks to "Footer"s notes and video I decided to start by removing the rear cover. If I pull the reverse selector rod back it clicks right into reverse... Hooray! I also noticed I can pull the rod back "almost" far enough, hear a click, and still not engage reverse. This is what I was feeling/hearing with the cover on. The (Bronze?) head on the shift lever is a little worn on the inside so I'm guessing that slight wear plus maybe some slop in the selector finger/cup/shaft are all adding up to a tolerance stack NOT in my favor. I'll see if I can locate a new Shift rod end when I call around for a new rear gasket. otherwise I'll check all the bushes and washer/spacers to see if I can tighten things up. I feel it's really close. I'll try and add a few pix. Thanks All!

[RacerX]

A few pix

[jbcollier]

Frankly, the Lotus shop manual is not very good on transaxles.  It uses words rather than detailed, clear photos.  The Renault manuals have way more large, detailed, photos of almost every step in disassembly and reassembly.

[RacerX]

a bit more progress. I replaced the main selector shaft bushing and seal. and tried again. Better, but still not pulling reverse. I noticed a bit of end-float on the #7 rocking lever shaft: (p3 below). So I added a bronze bush (washer) on the outside between the rear case and the reverse/5th detent cam: (P2 below). This removes ALL the end-float and justifies the shaft reward which maximizes the "pull" to engage reverse. Now I'm getting reverse! HOORAY!.... maybe...
 So during one of many trial and error rear cover removals I actually pulled the 5th gear shift rod/fork/synchro slider hub all the way out of the transmission. I was able to reassemble it, and it works smoothly (the 5th Synchro's are in excellent shape). The question is did I lose the 5th gear selector ball? (p1 below). When the shaft was out I noticed a bit of grease in the detent... and it looked as if the ball was never there. Was this ball removed when the external Rev/5th detent system was installed... like the reverse detent plunger and spring?
Thanks! Mark
 

[2766R]

Hi Mark,  I'm going to take a crack at this.  Mind you, I'm no expert but I have a theory.  The reason for the ball in question (again, my theory) is to prevent only one selector shaft at a time.  In other words, once one selector shaft is moved, the others are locked out of movement.  One doesn't want more than one gear selected-expensive noises are sure to occur!  Like you, when removing the rear cover, I pulled off 5th gear synchro and gear.  I feared the worst but I lucked out.  I saw that the ball was still perched in its bore.  This is why the manual instructs selecting 4th to prevent 5th gear selector shaft from moving.  If you think about it, one could theoretically position the gear selector to grab two adjacent selector shaft notches coincidentally, absolutely to be avoided at all costs.  I hope this helps.
To repeat myself, just my theory.  Anyone thinks I'm misguided, please do enlighten.

Gerry     

[RacerX]

Thanks Gerry,
 I think you are correct. I'm going to pull the rear cover again (in 4th) and if the 5 gear selector shaft is locked I'll know I'm ok.
-Mark

[RacerX]

Success! When 4th is pulled it locks out 5th. I'm going to assume the ball is still where it belongs. As I continue to work with this I'm thinking a tiny bit of end-float in the rocking lever shaft might be desirable. I'm going to look for a slightly thinner external bush/washer to see if I can remove a little tension and still preserve the new found leverage that solved reverse.
Thanks, Mark

[RacerX]

Update, I've got the gearbox back together. One interesting note- I ordered the wider (11mm) output shaft seals and it turns out my box uses the thinner (8mm) size. in fact there was a 7.5 wide seal in there. I thought the later box would have used the wider seal... not mine I guess. Question: is there a torque spec for the rear cover bolts? I don't see one in the shop manual. Hope to get this back in this weekend. Going to use my engine crane to help guide it in.
Thanks!
Mark

[jbcollier]