Spitfire gearbox overhaul

[Jonah]

Is the damage to the tail spigot bush significant?

[Pete Lewis]

cant tell from the pic but it should be a nice spin on the shaft spigot

has it been turning in the hsg. ???   the inside is the working surface if its a loose fit you could use a loctite bearing fit to hold it in place that works well

dave twigger is a good guy to talk to at Contact Us (odspares.com)

Pete

[Jonah]

Is it possible to remove the main bearings from the shafts without a press?

[Pete Lewis]

yes   most use a vice  and a drift with decent mallet 

there is a relief in the case bore to allow access witha drift/punch 

once you drop thecluster and pop the stem gear out you can start the mainshaft by knocking the shaft back ito the case then drift the bearing out the case 

tilt the mainshaft to remove it from the case  

input shaft is easy just suppoert the brg on a vice and knock the shaft through 

do remove all circlips first ha !

Pete

[Jonah]

Thanks Pete, this is the latest on the main shaft position. Sorry for probably a daft question but will I damage the casting by using a drift to push the shaft through using wood or metal blocks underneath the bearing?

[Pete Lewis]

that should work ok   they are not that tight  a few good whacks should pop it off 

or stick a drift on the bearing and belt it up the shaft through the hole in the case 

Pete

[johny]

Yes youve got to be careful that youre not bashing gears together inside the casing if tapping the mainshaft through. The laygear can tend to move from the bottom of the case and then theres contact between gears😞 To help avoid this you can put in more packers under the bearing as is to starts to move and of course if possible try to support the centre race of the bearing to minimise the stress on it (if its to be reused)... 

[Pete Lewis]

when its outand ready to strip you may find the 3rd gear circlip is a pig to remove often needs a sharp chisel and give it a chop 

always buy a few as spares you must never reuse on of thes small circlips even if you justfitted it and wish to remove again  

reforming a spread one will end up in it coming off 

and under the 1/2nd hub is a small ball bearing which locates in the mainshaft  dont loose it 

Pete

[Jonah]

I can see that the third gear circlip is already damaged in situ, there also appears to be some dents in the input shaft ring where it meets the bearing, looks like it’s been whacked to remove the bearing and damaged in the process

are the circlips common parts, they’re out of stock at Canley? 

[Pete Lewis]

this says in stock TKC6444

Gearbox Mainshaft : Canley Classics

and mick dolphin s a brilliant guybat having the original stuff hard to find  TSSC Weblist 0123.xls (mickdolphin.co.uk)  shows as available 

Pete

[Jonah]

Thank Pete, should I replace the other circlips?

[Pete Lewis]

most of the others  ie  back of the bearings are usually reusable  providing like anybcirclip  they dont get over streatched on removal 

they are more tolerant than the 3rd gear silly one ( used on 3 syn and 4 syn boxes )

to refit the 3 rd gear circlip often use a conveinient socket to pop the clip over the start of the splined shaft 

on production a nice tapered sleeve would be used to lead the clip on 

opening with  C  pliers will make it a loose fit as this tends to over stretch the clip 

they can be re cloded in a vice but its not recomended    this silly clip has a lot of enemies  it wants no room to wriggle 

Pete

 

 

[Jonah]

I thought I’d update my progress on the spitfire gearbox and overdrive rebuild, attached pic

after some great advice from a very patient Dave Twigger the overdrive has new bearings, oil seals etc. some difficult to find parts from Mick Dolphin added to the list 

with a gearbox rebuild kit from Canley along with a remote control kit the job is done and ready to go back in the car

the Midwest Motoring videos on YouTube were also very helpful 

thanks to everyone who gave me advice and guidance on this thread

All being all a test drive awaits

best Julian 

[Pete Lewis]

we await a test run result  

 

Pete

[Jonah]

And there was me thinking of a test run this weekend!

getting it back in is proving more difficult than getting it out

My question is does the driveshaft need to be removed to create enough space?

 

[Pete Lewis]

if the prop is rearwards on its telescope(if it has one) then it should go in ok  might need turning/rotation to clear the clutch hsg with the heater etc.

you need it in 4th gear and be able to rotate the coupling to get the input splines aligned with the clutch disc

and i use an odd bit of timber to use as a sight gauge to judge the gap between back plate and C hsg is actually parallel  its easy to think its ok when its \/ and the engine needs more jacking to get it all  | |

Pete

[Jonah]

Thanks Pete

There’s no telescope in the driveshaft, it looks as though the shaft needs to drop down otherwise there just isn’t enough gap to lower the gearbox into position 

Julian

[Pete Lewis]

can you get under and disconnect the prop at the diff and pull it rearwards enough to drop the tail of the box ??

there' s a question  ... your managed to get it out , whats changed  ????

have you got a couple of long studs in the back of the block to aid alignments 

Pete

[Jonah]

I agree it is odd, I was hoping the driveshaft would drop down after it was disconnected from the overdrive, but it didn't

Also the overdrive shaft nut protrudes beyond the flange which makes the alignment tricky

is there a way that I can drop the driveshaft down to get the gearbox better positioned?

 I’ve got three studs at the top of the end plate, the gearbox aligns with them but because of the angle there is a huge gap at the bottom 

I’ve loosened the engine mounts and disconnected the exhaust from the manifold to allow some movement 

Julian 

 

[dannyb]

I always drop the prop at the diff and pull it back to get some room.

I also use two longer studs at the top of the engine to help alight the bellhousing with the engine angle. A trolly jack with wood bridging both engine and bellhousing helps get the angle right. 

I done this about 5 times and always on my own.

Danny

[Josef]

Sounds like rather than trying to drop the prop, jacking under the rear of the sump to tilt the engine and gearbox up at the rear might help here? You can get it surprisingly high, then drop it down slowly and get the tail shaft aligned with the prop that way. 

[johny]

yes whichever way it came out it must be able to go back the same way🙂

[johny]

saying that the clutch hasnt been disturbed has it?

[Jonah]

I’ve just pulled the unit back to check for any damage to the clutch etc, thankfully all good

the position of the driveshaft flange is the problem because it won’t let me lower the unit enough to get it in at the right angle, in other words there’s not enough gap, getting the unit out in the first place was really difficult, but as you say it came out this way so should go back

ill use longer studs and drop the prop at the diff end which makes perfect sense

thanks all Julian 

[johny]

I take it then the back of the engine wont jack any higher to get the angle right?