Why are these Spitfire gearbox's so weak ?

[wimpus]

Yesterday suddenly no overdrive anymore.

So had a look.. still 12v to the solenoid and it clicked.

 

This morning stripped out the interior.

Solenoid tested out of the box.. working fine.

I had bought a pressure gauge.

So fitted that... no pressure at all.

 

Drained the oil.. metal bits could be heard falling !

In the last 4 years i have rebuild my 1 in the car and spare every year once.

-First time 3rd gear clip.

-2nd front bearing 

-3rd time front bearing 

 

Last october/november the last one failed massivly.

Laygear broken + shaft, all bearings bad, mainshaft tip bad etc etc etc.

Now this..

Its not the 3rd gear clip , but a spacer from the mainshaft bearing.

 

Really dont know what to do.

As the one with bad mainshaft etc.. still could not get the parts for it.

And yes I do around 15.000miles / year.

[Mathew]

Assuming you have the 1500 j type box. Drove with one of these for 20k miles no problem and the box was second hand to me! I have a lead right foot as well!

So why is yours failing? When you rebuilt it did you fully rebuild it or just change the bit that had failed? Oil used? Driving style? Do you ease up when changing gear or slam it in?

[Pete Lewis]

apart from needle rollers , spigots and spindles , departing circlips ,chimbled synchro teeth /baulk ring wear 

most other parts are fairly good , its true they are all getting a bit past it but to be so unlucky 

is not representative of normal 

[Nick Jones]

2 hours ago, wimpus said:

but a spacer from the mainshaft bearing.

Do you mean the cage that keeps the balls in place in the big ball-bearing race?

The decent quality RHP(?) main bearings have been NLA for a while and the ones I’ve seen supplied instead were so dodgy looking I ended up choosing the best of the used ones. This may be the root of your problems?

Silly thing is, the decent bearings are still available in every detail except the external circlip groove, so it wouldn’t be a major challenge to get a batch converted.

In general terms the single rail box in the 1500 is about the strongest factory combination there is (not saying all that much it is true), but all getting old and well used now.

Nick

[GT6M]

thats the main shaft ring, that ods 3 rd gear in spot

 

Most likely been owa expanded  if re used

or a  dodgy after market ,n

[Mathew]

9 hours ago, Nick Jones said:

Do you mean the cage that keeps the balls in place in the big ball-bearing race?

The decent quality RHP(?) main bearings have been NLA for a while and the ones I’ve seen supplied instead were so dodgy looking I ended up choosing the best of the used ones. This may be the root of your problems?

Silly thing is, the decent bearings are still available in every detail except the external circlip groove, so it wouldn’t be a major challenge to get a batch converted.

In general terms the single rail box in the 1500 is about the strongest factory combination there is (not saying all that much it is true), but all getting old and well used now.

Nick

If all that is needed is a groove , if you know the bearing let us know it, so i could get some at brt and use the lathe to cut the groove. 

[wimpus]

Nick & Marcus, 

Ive used KSM (japaneese) bearings on mine.

Its not that what has failed me now.

But a spacer that runs both sides next to the bearing of the mainshaft tip.

Its not the 3rd gear clip (always replace that one when the box is open).

The parts that came out, i had measured then.

To thick to be 3rd gear clip, so had a look at my other failed box.

 

[Pete Lewis]

2 hours ago, Mathew said:

If all that is needed is a groove , if you know the bearing let us know it, so i could get some at brt and use the lathe to cut the groove. 

I have an ex |Skf man with a stash of  skf  rms8 that just need the groove, 

will try to locate them and let you know 

Pete

[Pete Lewis]

Mathew   i can get hold of 20 orig skf   grooveless  RMS8  bearings     (two per gearbox )

how would you wash the race after machining  ???

and you need a heck of a lathe and tool to machine the very hard outer race

IE skf want £5 to add a groove ans washout   per bearing   its not ecconomical 

hence they sit in a cupboard 

Pete

[Mathew]

1 hour ago, Pete Lewis said:

Mathew   i can get hold of 20 orig skf   grooveless  RMS8  bearings     (two per gearbox )

how would you wash the race after machining  ???

and you need a heck of a lathe and tool to machine the very hard outer race

IE skf want £5 to add a groove ans washout   per bearing   its not ecconomical 

hence they sit in a cupboard 

Pete

Hi pete, how much per bearing are you paying?, of all the times im in devon for the next few days, back late Wednesday. I can machine on the works lathe and wash out at home in my parts washer. I get a huge discount buying bearings through work. I won't be able to find out till at least Thursday how much. Have you already bought them?

[wimpus]

So what i think is that part no 8 or 11 has failed.

 

Now to search for a new mainshaft and input for my spare box ....

[johny]

That would be unusual as those rings are only to limit the movement of the tip needle roller brg. I wonder if the mainshaft has somehow been pushed up too close to the input shaft but then I would have expected the needle brg to have failed first...

[Pete Lewis]

5 hours ago, Mathew said:

Have you already bought them?

they belong to a local member who I  should see tonight at the pub meet , no idea what he paid or wants  

(probably staff sales so very cheap ) 

they are genuine skf     skf want  £3.50 to do the 20 and includes new snap ring and wash (quote of today ) 

there's  more to discuss on this it could all be a red herring 

more tomorrow 

Pete

[Mathew]

3.50 to do the lot sounds good, unless thats each! Doing it ourselfs would not include a new snap ring! So you would need to retain that. 

[daverclasper]

22 minutes ago, Mathew said:

3.50 to do the lot sounds good, unless thats each!

Am I missing something?. £3.50, sounds ok for one, to me?. 

[Pete Lewis]

sorry  covid brain    its EACH    

Pete

[thescrapman]

£3.50 each still sounds cheap to me.

[Peter Truman]

I agree a very cheap charge by SKF for the work reqd, I'd buy a couple as spares..

[Mathew]

3.50 plus cost of bearing. So really does depend on the cost of the bearing

[wimpus]

Seems the mainshaft + 1st gear is scrap in my spare box

New 4th gear/motion shaft, 1st gear, mainshaft etc ordered .. 

Parts coming from Germany, the Netherlands and the UK.

Lucky enough bought a NOS laygear last year.

Hopefully can build up the spare box.

And hopefully the overdrive works again after a good clean out..

Its going to be an expensive one.

[Pete Lewis]

that looks like lack of lubrication

Pete

[Nick Jones]

Agree....

[Mathew]

It does look like pickup from poor lubrication. 

[Mathew]

What oil has been used?

[wimpus]

23 hours ago, Pete Lewis said:

that looks like lack of lubrication

Pete

Strangly.. box was full of oil.

But i think the laygear shaft failed or bearings

Swarf everywhere.. also in all the sycro hubs, mainshaft top bearing etc etc etc 

 

80w90 gl4 (millers) was used.