Triumph Gt6 mk3 - 2nd and 3rd gear noises

[Joanna K]

23 minutes ago, johny said:

What did the laygear bearing surfaces look like Joanna? They usually last better than the layshaft but if this is the boxes second rebuild might now have worn through the case hardening meaning that the wear rate accelerates😢

Hi Johny,

it has some wear on one end in the bearing surface. I’ve installed the new bearings and temporarily installed the layshaft and spinning the cluster on it I can feel no roughness 

[Pete Lewis]

with any gearbox  there is utopia and compromise   it all depends on how hard you want to drive it and are you driving to scotland evert week or tootling to area event 

some wear you can get away with but some needs replacing 

a new cluster is very expensive   so its a balance  act   of usage and ££s 

the mainshaft and lay spindle will make a big improvement   it may not be as good as new  thats more finicky and costly 

pete

[Pete Lewis]

thanks for message  will post picture here its easier than on the message system 

this shows a good deal of rotational wear but its really quite usable  and better than the pic suggests

[Pete Lewis]

used part posted , wait to see if it gets used 

Pete

[Joanna K]

Saturday, between the rain showers, fun. New clutch and backplate

[johny]

Nice feeling knowing that the clutch is new and not going to need doing for a long time! Is that an alloy backplate? If so extra easy does it when the box goes back in... Also have you checked the bronze input shaft support bush in the crank for wear? 

[Pete Lewis]

and if the new throwout bearing is a thin 16mm  you need to add a washer under the clutch Hsg pivot post    its a light push fit in the alloy hsg.

the bearing should be 19mm thick   moving the post out a little corrects the angle of the arm 

its a common problem   ) theres a recent post with a lot of this discussed on a 1600  ( it applies to all  6 cyls  )

Pete

[Joanna K]

41 minutes ago, johny said:

Nice feeling knowing that the clutch is new and not going to need doing for a long time! Is that an alloy backplate? If so extra easy does it when the box goes back in... Also have you checked the bronze input shaft support bush in the crank for wear? 

Johny, yes it is aluminium. And no, I haven’t checked it yet, I mean - I haven’t thought of it. Thanks for the heads up 

[johny]

According to the manual limits of clearance shaft to bush are 8.5 to 5.8 thou. Hard to measure but definitely not a close fit....

[Pete Lewis]

why not use the stem gear from the stripped box to check for any nasty waggle in the spigot bush  ???

Pete

[Joanna K]

2 hours ago, Pete Lewis said:

why not use the stem gear from the stripped box to check for any nasty waggle in the spigot bush  ???

Pete

All seems good in this area. 
 

PS- I made slow progress on the mainshaft assembly this week. I found all springs from both gear hubs to be broken. Waiting for a delivery from Canleys 

[johny]

I dont know about accidentally, youve got to open up each hub to check the springs as part of any rebuild havent you? Ive found broken ones before and its definitely best done inside a plastic bag!

[Joanna K]

I had to use a magnet to take mine out 😅 

[Pete Lewis]

and whilst the springs look very similar  the 3/4th hub are different to 1/2nd  in their lengths 

on refit slide sleeve down and prod each ball with a screwdriver  blade just enough to let the sleeve start to hold it when all 3 are in place push sleeve fully down

you cuold wire the sleeve in place to stop things flying apart on rebuild 

as for reassy i always do this vertically  i use an old stem gear in a vice ( a wooden with hole for mainshaft tip works)  and drop the whole case / cluster and mainshaft 

onto the support  you can then knock the bearing down the shaft and into the case  the advantage of this seemingly daft clue is gravity stops the two collet thrusts on 2nd continually jumping out as the gears jump when you tap the bearing on   

yes its a bit heavy and unweildy but this works  and  saves repeated cursing 

always take care with the 3rd gear circlip  you dont want to over  spread this on refit   easily done   needs to be a good tight fit 

as they can decide to pop off if slack 

have fun  

Pete

[Joanna K]

1 hour ago, Mathew said:

This is the tool for holding the mainshaft in place while i press the bearing in.

 

I’ve never seen one like this before

[Pete Lewis]

hence use old input shaft or make a support out of hard wood 

another thought is use /fit the exisiting input shaft a bearing  use that as a mainshaft support 

drop the whole assy over and into   once in place tap the bearing down the shaft and into the case 

then revert to upright and raise the cluster with your wire/string loop , pop the new shaft in place keep an eye on thrust washers 

in fact a short bit of dummy (anything)  shaft to locate the thrusts can work popped in each end of the spindle bore to hold the thrusts in place 

Pete

[Joanna K]

1 hour ago, Mathew said:

In practice i never found the main bearings hard to put in place, held in position by the ring and covers both sides.

That’s my job for tonight! Almost there, almost there… 

[Pete Lewis]

let us know how many times the thrust collets jump out  then 

up  end it   ha    Pete

[Pete Lewis]

when we rebuilt PaulH's   box   last month the rear bearing was a right tight pig to fit tight down shaft and in case  a lot of whacking

with the coal hammer well you know what i mean  

Pete

[Pete Lewis]

having  a press  ...........  not all have the luxury 

many have a variety of ....hammers   

agree you need extra pair of hands is very useful

on your own its a bit of a acrobatic  rules apply

or them   split thrust's  are ...........   out again ...........and again   

or they're  are out and you dont realise ....what you mean  end float  !!

Pete

 

[Joanna K]

Any other possible things that could go wrong tonight guys? 😜 

[johny]

The worst thing is not knowing youve done it right until its back in the car and you drive it! Ive wondered if a beefy electric drill couldnt be used to power the rear coupling on the bench and then go through the gears - should test the synchros and better than nothing?

[Joanna K]

1 hour ago, johny said:

The worst thing is not knowing youve done it right until its back in the car and you drive it! Ive wondered if a beefy electric drill couldnt be used to power the rear coupling on the bench and then go through the gears - should test the synchros and better than nothing?

Johny, that’s the worst thing…hopefully I will be able to check it this weekend. I took thousands of photos to document the whole process, so it wasn’t difficult to put it all back together. Unless, I skipped a photo at some point 😂

[Pete Lewis]

you need something pretty powerfull to drive the box

being involved with gearbox test beds in the factory and solving synchro problems its not a feasible diy job

just compare what whacking big drill speed you can get with clutch and propshaft revs and power 

if the dog teeth and sleeve have well defines chamfered teeth the baulk  ring doesnt bottom out  and  wrings onto the cones firmly by hand   and you get a half tooth rock over between sleeve /ring/ dog teeth  

it will work

[johny]

hmmm most powerful 240v drill I can find is 1500w so around 2hp to turn the 3 shafts of a small chassis gearbox?

It might work but the drill motor probably wouldnt last very long due to overheating - I'll report back when I do it one day😲