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Spitfire 2nd Gear Crunch


Jonah
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My Spitfire Mk3 gearbox crunches into second gear, it has a D type overdrive

I’m wondering if is this likely to be a synchro problem requiring replacement or could a clutch problem be the cause?


thanks in advance for any advice for a wishful thinker!

 

 

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Either or both!

Check the cluch is moving nicely with no excessive play in the system. And the pin hasn't partially fallen out the bellhousing

But if it is only into 2nd, not 3rd under similar revs etc, chances are the synchro is worn. 2nd tends to wear rather faster than the others. 

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yes almost certainly synchro and unfortunately a complete gearbox stripdown to replace it. Its like a miniature clutch and they wear out just like the main one then if you keep crunching other components in the gearbox can suffer. In the meantime after pressing the clutch try waiting a fraction before changing up and on down changes learn to double declutch😲

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Disconnect Battery, Remove one, or both seats. Remove H frame. Remove the tunnel. Undo speedo cable.

Undo propshaft and disconnect. Remove the slave cylinder from the bellhousing.

Support the engine under the sump, undo the gearbox mounts. Jack the sump up a tad to lift the gearbox tail. Remove starter motor, and undo all the gearbox to engine bolts, leaving the top 2 in place. When ready, indo the top 2, and slide the box back and off/out. Heavy!

Find a good used box, same as herald (unless yours is overdrive) Or get yours rebuilt.

To refit, it is teh reverse. EXCEPT get 2x 3"+ bolts, 5/16 thread, and cut the heads off. Take the 2 studs out of the block which are the 2 top fixings, and replace with your new special studs. These make refitting the box MUCH easier, as it keeps everything perfectly aligned. 

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I would advise rebuilding rather than dropping in another used one. It’s relatively easy to do, and getting them in and out is enough of a struggle that you don’t want to do it again in a hurry if the used one turns out to be not up to much! (Just built and swapped one each in my Spit and Herald)

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I’ve been thinking of buying a mobile lift/tilter from CJ Autos to raise the car, do you think it would be possible to remove the gearbox from below using this?

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there are rebuilds made up as a "kit" but i would say you need to look see first 

if luton is too far a run for me  to guide you can you find someone in your local area who can advise  

if all is quiet and only 2nd is failing you may only need a set of circlips and a new baulk ring  not a whole kit 

there are a few things in the tooling like circlip pliers , a mallet and steel punch and a dummy lay spindle 

do you have a decent workshop manual ???

pete

 

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1 hour ago, Jonah said:

I’ve been thinking of buying a mobile lift/tilter from CJ Autos to raise the car, do you think it would be possible to remove the gearbox from below using this?

I bought a (used) version f that lifter. It is difficult on  aspitfire, as it lifts under the sills (but mine wasn't narrow enough) so you would end up with lifting the tub, with the chassis and engine etc hanging off the body. Not ideal. I sold it and rely on a good high lift trolley jack and tall axle stands. I also stack 2 or 3 wheels under the centre if the car, just in case....

 

Next. Beware buying a kit. The quality is variable. The better rebuilders have a supply of good used components, and will swap synchos around. Or use good s/h synchros. Bearings may well be fine, in fact anything that is in good condition is worth reusing. 

For refence, I had my type 9 box rebuilt by BGH, they supply lots of Ford specialists, rally chaps etc. They were happy with most of my box, but it had previously been fitted with repro synchros. They fitted used Ford items. They also changed 5th gear (mine was nearly through the hardening) and reground the synchro hubs etc. No new parts at all except gaskets etc. 

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I’m going to need some guidance I think once I’ve got the gearbox out as I haven’t done this before

Thank you Clive, ill skip the lifter idea, I’ve been searching for a safe way to lift the car so I can work underneath, I’ll keep researching!

julian 

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you only need to lift the front enough to get to the bolts around the bell housing  once removed you can drop it back on the deck 

with OD its going to be a bit heavier than it looks , def seats out and some remove the steering wheel to aid access.

green WSM  ....

thats a good start   but you dont need any Churchill special tools on these gearboxes 

a dummy lay spindle (made from anything) a set of punches  a hammer  circlip pliers  

being overdrive has some advantages  (as on a std getting the speedo worm off can be a faf ) 

spares   get  a gasket set  new synchro baulk ring , some ep90 gear oil ,and 2 or 3 mainshaft3rd gear circlips as never re use and you may overspread one on refitting 

so a spare is useful to have 

bearings tend to be always reusable 

tube of sealer etc 

Pete

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1 minute ago, Jonah said:

I’m going to need some guidance I think once I’ve got the gearbox out as I haven’t done this before

Thank you Clive, ill skip the lifter idea, I’ve been searching for a safe way to lift the car so I can work underneath, I’ll keep researching!

julian 

I have tried all sorts, and concluded tolley jack and stands are easiest. Mobile axle stands (google them) are really good, and aloow you to shuffle a car around if space is tight.

 

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Thanks Pete, would it be sensible to replace the synchros on all gears?

I’ll look into the mobile axle stands Clive, my problem has been getting a low profile trolley jack underneath to start with 

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1 hour ago, Jonah said:

Thanks Pete, would it be sensible to replace the synchros on all gears?

The problem seems to be finding good pattern part synchros as some might not work very well or last long so it would probably be best to swop rings around as much as possible. You can inspect and check the original rings and use the best on 2nd gear then use the replacement on 1st or 4th depending on whether yours is a 3 or 4 synchro unit....

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1 hour ago, Jonah said:

Thanks Pete, would it be sensible to replace the synchros on all gears?

I’ll look into the mobile axle stands Clive, my problem has been getting a low profile trolley jack underneath to start with 

Sealey do one. Or if feeling flushed, buy a weber https://www.weberuk.com/shop/trolley-jacks/standard-trolley-jack/wdk20/ which is rather nicer to use

Some cars need the front wheels to run up onto 1" thick planks. 

Re synchros, the hubs may well need resurfacing (with fine abrasive paper) to give a bit more grip on the synchros

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there is /was a problem with new rings   some have been turned up on a lathe and the chuck jaws distort the ring so it becomes lobed

totally useless  

simple hand test is to twist/wring the ring onto its gear cone  it should grip quite easily and there must be a decent few mm gap between the 

ring and its gear face  or its bottomed out 

will load a how it works but need to be on my PC not lounging 

Pete

 

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I did buy a single County branded synchro ring from Paddocks which is now in my Herald. It looked ok, felt positive on the gear cones, and so far seems to be working fine. 

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Mike Paworth, based in Coventry, was very helpful for advice and parts when I broke my Vitesse gearbox.

I lift engine and gearbox out as a unit, only tried through the car once, but depends on equipment available.

Regards

Paul.

 

IMG_20220110_122423.jpg

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