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Spitfire Spitfire gearbox overhaul

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One improvement that I think you should consider is lightneing the flywheel. Any competent machine shop can take the outer unneeded weight off the back of the flywheel, below the ring gear. Depending on the design of the flywheel can vary anywhere from 6 to 18 or so pounds. An inexpensive machining(usually less than one hour of shop time) and measurable results, in that the engine spins up faster.
 
I think Shipwright's disease is setting in. I went to redo the front brakes and noticed that the inner piston on the driver's side caliper is frozen. So, I guess I'll have to add a caliper rebuild kit onto the next order along with the bronze bushings for the clutch release swivel pin and the slave rebuild kit.
 
jdubois said:
So, I guess I'll have to add a caliper rebuild kit onto the next order along with the bronze bushings for the clutch release swivel pin and the slave rebuild kit.
Click to expand...
You might want to add a couple of pressure plate screws (PN 146176) or get one or two locally (grade 8) to have on hand for when you reinstall the clutch.

Those screws need to be torqued to 22 ft/lbs, very inconvenient if one snaps.
 
I heard back from John at QM. He took the tranny apart and reported what I knew to be true, the needle bearing had disintegrated. He also reported what I feared to be true, the main shaft is toast. He said he had a few good ones there though and he'd put one of those in for $50. He thinks the input shaft is ok, but wanted to make sure. If that's bad too, it'd be another $40. He also said all the bearings and syncros were bad and needed replacing. The good news was that he was pleased with the condition of all the gears. He said they looked really good, and didn't need replacement.

The end result: total bill will be $515, or $555 if the input shaft needs replacement. I gave him a 50% deposit and told him to go to work. So I've now got about two weeks to get the rest of the stuff done. Parts for the clutch, bellhousing, etc. should be here tomorrow.
 
Dumb question of the day:
If John was pleased at the condition of all the gears, where did those teeth lying in the bottom come from??
Inquiring minds want to know!
Jeff
 
Bugeye58 said:
Dumb question of the day:
If John was pleased at the condition of all the gears, where did those teeth lying in the bottom come from??
Inquiring minds want to know!
Jeff
Click to expand...

I asked him about that. He obviously didn't see the bits, but he said it was all probably parts of the disintegrated bearing that just looked like teeth.
 
Yeah, that's not a bad idea. But if he can't spot a damaged gear, I'd be a little afraid of having him rebuild the tranny /bcforum/images/%%GRAEMLIN_URL%%/eek.gif
 
Oh, I wasn't doubting <u>John</u> one bit. I just thought he may want to see the picture to understand <u>our</u> befuddlement! /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
Jeff
 
...and don't forget how old these units are. It may have in the past had a botch-up gear replacement without a thorough cleaning... residual bits not well flushed, hiding in the shadows. Stranger things have been known to happen.
 
ok, probably a question for john, but why are there refurbished transmissions for sale for 675 plus shipping on his site but you seem to be getting away on a pretty thorough rebuild for 555? is this the cost of having a rebuilt tranny when you need it rather than having your own unit refurbished?

i'm just starting to hang things off my newly painted frame so i don't need one soon, but i'd love to send mine in for a recondition or rebuilding...that differential too (but i know john doesn't do that)...
 
Flinkly said:
ok, probably a question for john, but why are there refurbished transmissions for sale for 675 plus shipping on his site but you seem to be getting away on a pretty thorough rebuild for 555?
Click to expand...
As mentioned, the cost depends heavily on what parts have to be replaced. The $675 probably covers the average condition of incoming cores, while jdubois's core was better than average.
 
Yes, I think TR3driver has it. John mentioned that he just got in another early spit gearbox which he had to advise the owner not to bother rebuilding, since it was in such bad shape that it would cost more than the $675 for a replacement unit.
 
Oh... you people ask too many pointed questions /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

I don't think it was terribly well cared for mechanically by the last few owners. It was apparently well cared for by the original couple who bought it new. I've got all the service records where they dutifully took it to the shop regularly. But when they died it ended up with their son-in-law who didn't care about it in the least and just stored it for a few years. Then, when he finally put it up for sale, the owner previous to me bought it because it was such a good deal and in such untouched shape. But he already had a few spitfires and so it just sort of sat with him too. He did have the few rust spots fixed and gave it a respray, but admitted he hadn't done anything to it mechanically.

As I've come to learn in the Ferrari world, low mileage examples aren't a panacea. They come with their own problems.
 
I rebuilt the gearbox remote control last night. A bit of pressing sleeves in and out, and a circlip that clearly wasn't intended to ever come off (I had to dremel it out), and everything is back together and feeling nice and tight.

One question, there didn't seem to be any lubrication on any of the joints. Should I put some in, or are all those plastic sleeves and washers self-lubricating?
 
Never tried on a Spit, but I'm a big believer in giving "self lubricating" bushings some help. Sounds like a good place for silicone grease (which is very water resistant and won't attack rubber; but does tend to attract dirt worse than most).
 
Ok, I moved on to the clutch slave cylinder tonight. I took it apart and inspected it. The plunger seal was shot, which is clearly why the thing was leaking. The plunger itself was pretty clean, smooth, and without any pitting except a very small amount on the front rim. The inner cylinder wall was also clean except for a crusty ridge about half way down, where the plunger normally sits.

I polished the ridge out with 00 steel wool, and there's a barely detectable ring of pitting underneath where the ridge was. I can only see it if I shine a light just right, and I can feel it with my finger but only just.

I went ahead and put the new seals in, reassembled everything, and tested it. No leaks. Am I good to go, or should I scrap the unit and get a new one?
 
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