Gearbox oil leak from bolt in adaptor plate.

[Markvh]

Hi, I have had an oil leak from the gear box area for a while. In an attempt to locate the leak, I have cleaned the whole box and J Type overdrive casings. I have let the car stand for 48 hours and a drip has formed. It comes from the bottom right hand bolt that bolts the adaptor plate (part number 312305) to the gear box (as you look forward from the rear of the gearbox). It’s definitely the bolt and not the gasket. I have cleaned it off and left the car to stand and the oil slowly seeps from around the bolt head. The next check is to run the engine warm to see if the oil still comes from the same spot only.
I was wondering if it is possible to remove the bolt, clean and replace with a thread sealant? Or does the bolt hole go through to the box casing therefore necessitating draining the box and overdrive? If so, should I remove the overdrive sump plate to clean the filter at the same time?
I’d like to cure the leak if it is sensible to do so. It is only small but the leak onto the drip tray does get bigger over time.
Also I have read that there are gearbox and overdrive breather points but where are they? I can’t find them.
can anyone advise or point me in the right direction for info. I’ve looked at various topics and the training notes.
Thanks. Mark

[sujitroy]

Hi. on my phone apt . the holes go through the box. maybe a suggestion.use light thread sealer. or take bolt out after drain and use copper washer. on bolt head.

[sujitroy]

I posted a photo of the gearbox breather hole. search gearbox pressure. the hole very small is on the top cover at the opposite end of the lever. I can't imagine getting to it in situ

[flying farmer]

Bottom bolts should have been fitted with copper washers from the factory as the holes do go straight through the casing.
Use the drain plug in the bottom of the gearbox as removing the overdrive sump will not drop the level far enough.
If you don't have copper washers, a plain steel one and silicone sealant will do the job.
Neil

[stag8manod]

Or a red fibre washer under a brass or steel washer.
Cheers Ian A

[Guest]

Hi Mark
I have not dealt with that myself but to my knowledge the gearbox was factory fitted with springwashers but glued in.
After repairs the gluing is usually forgotten about.
Again I am only told that individual bolts can be taken out one by one and the springwasher be replaced with copper seals.
But use a tray underneath.

[DJT]

If you fit copper washers then anneal them first, even if new. Removes any work-hardening and makes them soft enough to form a seal.

[Markvh]

Thanks everyone for your advice, it has been very very helpful. I guess the bolt will be a UNC 5/16" as the 1/2" spanner fitted?
Would an annealed 8mm copper washer be the thing to try and would it be possible to remove the bolt and reinsert with the copper washer with the oil still in the gearbox if I have another pair of hands to plug the hole while the bolt is out?
Should the spring washer fit back between the copper washer and bolt head?
Or am I deluding myself and oil will come flying out of the bolthole while the bolt is out despite an assistant's (read wife) finger plugging the hole? Is this a bit of a shortcut bodge and not likely to work?
I'm going to take it out for a good run tonight to see if any other leaks manifest themselves.
Thanks again. Mark.

[Guest]

get rid of the spring washer when fitting the copper washer

[steve.n]

Check there are no sharp areas on the sealing face of the bolt from the spring washer before replacing with copper ones.
Steve

[sujitroy]

I disagree that the boxes were fitted with copper washers.
I pulled apart three triumph boxes, within the last year: Stag non OD, Stag OD and one from a Dolmote Sprints w OD box. Spring washers were used in all cases for all 6 bolts. The only place I see copper washers is 2 on the upper bolts of the OD. The gearbox cone and the lay shaft plate.
Sujit

[flying farmer]

I disagree that the boxes were fitted with copper washers.
I pulled apart three triumph boxes, within the last year: Stag non OD, Stag OD and one from a Dolmote Sprints w OD box. Spring washers were used in all cases for all 6 bolts. The only place I see copper washers is 2 on the upper bolts of the OD. The gearbox cone and the lay shaft plate.
Sujit

I notice Rimmers only mention spring washers for the rear housing, but copper washers for the bolts in the bell housing.
I assumed copper washers were a factory fitment having found several boxes with them fitted.
It might well be a dealer fitment when owners complained their Triumphs were marking their territory due to insufficient thread sealing compound being applied when the gearboxes were built!
Neil

[Markvh]

I have taken the car out for a good run. The oil leaks through the bottom right bolt as you look at it from the rear of the car. I reckon i’m Going to try and fit a copper washer with the oil in situ. My wife will hold her finger over the hole while I fit the washer.
i notice that there is a slight seepage from the top right bolt but I don’t have a spanner short enough to turn the bolt because the tunnel is in the way and my small 1/4” drive socket and wrench doesn’t have enough room to fit on.
what does anybody else use? A sawn down spanner? Or maybe one of those joker wrench combination spanner’s listed on Machinemart?
Thanks. Mark.

[sujitroy]

here in the USA u can buy a crow foot wrench spanner set. not cheap. but useful in such situations. use them on the steering rack pipes also use them on the end of a torque wrench

[sujitroy]

drain the box. in addition to the copper washer use a light thread lock liquid.

just a thought could u use ptfe tape on the thread