Spitfire Spitfire gearbox overhaul

[jdubois]

I thought I'd start a thread for my gearbox overhaul, so that I can ramble on about it, ask questions, and keep anybody who cares up to date without starting lots of new threads. Sorry ahead of time for the rambling. /bcforum/images/%%GRAEMLIN_URL%%/blush.gif

As a small recap to those that might not have been following the other threads, I drained the gearbox oil in my '65 Spitfire the other day and with the oil came what looked like most of the needle bearing from inner end of the input shaft, along with possibly a thrust washer, and some bits of gear and/or syncro (thanks to Jeff for helping me figure out what it was.) So, I put the interior redo on hold and am preparing to pull the gearbox and get it rebuilt.

This evening I did a bit of preliminary work. I bagged up, labeled, and stored all the interior hardware, since it'll now be a while before it all goes back in. I then removed the remote control from the top of the gearbox and replaced it with a makeshift cardboard cover. I'm assuming when I ship the gearbox down, they won't want the remote control assembly along with it. I'll have to call Quantum Mechanics tomorrow and see what the procedure is.

I also disconnected the speedo drive, front of the drive shaft, and clutch slave cylinder. I think now all I've got to do is remove the starter motor and everything is off the gearbox. Then it's just remove the two rear mounts and the bellhousing bolts and the gearbox should be free. Oh, and gotta remove the exhaust mounting bracket.

This evening's activities left me with two revelations. First, the bellhousing seems to be wider than the chassis. So it looks like, without removing the engine, the gearbox will have to come out through the passenger compartment. Is that correct? I've got the seats and carpets out anyway, so this isn't a big deal, just wanted to prepare with some kind of padding to protect the dashboard, floors, etc. if this is true.

Second revelation, I was able to figure out why the stick felt so loose and rubbery when shifting. I stripped the gearbox remote control assembly apart and discovered that the shift lever bushing, which everybody seemed to think was the likely cause, was actually not that bad. Definitely in need of replacement, but not bad enough to be causing the trouble. The real culprit turned out to be the bushing on the coupling between the two shafts further down the remote. It had completely disintegrated and there was nothing left. That let the shaft attached to the shifter flop about loosely even when in gear.

All in all, not a bad night's work. I'm sort of on hold now though until I can get a buddy to help with the actual removal of the gearbox. I'm thinking it would be impractical to try and remove it by myself, and somehow I don't see my wife volunteering to help. /bcforum/images/%%GRAEMLIN_URL%%/rolleyes.gif

 

[Bugeye58]

Yup, it comes out from the inside. Not that big of a job, really. A couple of old blankets, or even better, moving pads, should do the trick to protect the interior.
I've never had help to pull one. You may want to pull the driveshaft completely, to give yourself a little more room to slide it back to clear the clutch.
Jeff

 

[cutlass29]

- you can get it out by yourself...did the '70 spit by myself. I did have to remove the driveshaft completely. There was no way the gearbox would come back far enough to clear the input shaft. Not a bad idea to remove it anyway while you're in there...check/replace the u joints...and so it starts!!!

 

[billspit]

If you are interested, I have the original transmission out of my MkI that I would be willing to part with. I need to clean out some and I'm sure I'll never need it as I have a fully synchro three rail sitting around. I went though the the trans before I installed it, but did not change the synchros since they seemed fine. The transmission worked fine, but I pulled it to replace it with an OD transmission. Shoot me an email if you wish.

 

[jdubois]

If you are interested, I have the original transmission out of my MkI that I would be willing to part with.

Thanks for the offer, but I'd like to stick with the original gearbox. At least until I find out I can't for some reason!

you can get it out by yourself

Ok, I may give it a shot then.

 

[IanF]

yep... removal & installation is more or less a 1-man job... mainly because there's not much room for two people.

I used a jack under the car to help with lining up the input shaft during installation.

Yep, the bellhousing is tight fit getting through the fire wall.

It'll be a good time to check/inspect/bleed/replace the clutch hydraulics while the tranny cover is off. Basically impossible to get to from below, as far as I can tell...

 

[jdubois]

It'll be a good time to check/inspect/bleed/replace the clutch hydraulics while the tranny cover is off. Basically impossible to get to from below, as far as I can tell...

I did actually manage to bleed the clutch slave on my first car ('76 Spit) from underneath. That was way back in 1993 when I was younger and more nimble, and didn't know you weren't supposed to do it that way. But getting the slave actually off from underneath would be the real trick!

Anyway, I have already bled the hydraulics, and they feel good. I don't want to take the slave apart without needing to because I've had them fail on me after I've done that in the past. I've found it's a lot easier to get the interior apart and the tunnel cover off on the earlier Spits than on the later ones, so clutch slave replacement wouldn't be a big job if it becomes necesssary down the line.

 

[TR_Jim]

I found that raising the engine a bit with a jack and block of wood on the oil pan caused the rear of the gearbox to raise high enough to clear the driveshaft. I also like to put a piece of 1/2" conduit, or other pipe, across the frame under the front of the bellhousing. It keeps the gearbox from falling between the frame and makes it easy to pull the gearbox back.

 

[jdubois]

I also like to put a piece of 1/2" conduit, or other pipe, across the frame under the front of the bellhousing.

I was thinking along these lines, glad to hear somebody else tried it and it works!

 

[Bugeye58]

Just don't forget to support the rear of the engine with a stand of some sort!
Jeff

 

[jdubois]

I didn't get as far as I'd hoped tonight. It wasn't long after I put my son to bed that my wife started bugging me to watch the new Heroes we tivo'd last night /bcforum/images/%%GRAEMLIN_URL%%/rolleyes.gif. But I jacked up the engine a bit and put a stack of wood blocks under the rear of the sump pan, then removed most of the bolts between the engine and the bell housing. I decided I needed to take the engine bay side shrouds off to easily get to the rest of the bolts, and that's were I sort of petered out for the evening and relented to my wife's pleadings. But tomorrow night I should be set to go, just a few more bolts and then I can get that sucker out.

I took the opportunity today to take my dash support bridge in to work, sand it down, and apply a fresh coat of black wrinkle finish to it. Looks like it turned out pretty well. Might as well tackle these things while I can.

 

[jdubois]

I'm afraid Basil's profanity rules keep me from expressing my true feelings about my experience this evening, but the gearbox is now out! It actually wasn't all that bad in the end, just that the gearbox got hung up on the rear end of the exhaust header, and so I had to stop and take the whole exhaust system off. I wasn't expecting that, so it was a little frustrating. But once I did that, it came out without too much trouble, though I thought for sure I was going to damage the dashboard trying to wiggle the bell housing out from under it.

Anyway, it looks like I'm all the way down the rabbit hole now, and there's only back up to go. So somebody give me a pat on the back for that! /bcforum/images/%%GRAEMLIN_URL%%/cool.gif I'll get the gearbox crated up and shipped down to Connecticut tomorrow, then begin ordering parts to do what I need to while it's away.

As it turns out, my porterfield brake pads and shoes came in today, so I can get the brakes rebuilt during the down time as well.

 

[DrEntropy]

Sounds as if 'sall good! I would have cautioned about the inner edges of the bell-housing casting: VERY sharp. You have already passed that stage tho.

With what you've already accomplished, is there a compelling reason you've decided to NOT do the box rebuild yourself? They're really a very straightforward unit; with a good manual and this place (BCF) it should be "do-able". A number of us have done this ~repeatedly~ and single-handed. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

 

[jdubois]

Sounds as if 'sall good! I would have cautioned about the inner edges of the bell-housing casting: VERY sharp. You have already passed that stage tho.

That's a very good warning (ask me how I know /bcforum/images/%%GRAEMLIN_URL%%/smile.gif )

With what you've already accomplished, is there a compelling reason you've decided to NOT do the box rebuild yourself?

Mostly memories of a failed rebuild attempt on an MGB box years ago. I couldn't get the tolerances right no matter what I did, and every time I tightened the whole thing it would seize up. So I spend a bit of time and money and then had to send it out anyway. That's made me very gun shy.

 

[jdubois]

Ok, I just shipped the box down to Quantum Mechanics. Not a bad deal really, they'll rebuild the thing for $325 + parts and shipping. I'm happier doing that than trying to do it myself, and now I can spend the three weeks or so turn around time working on other parts of the car.

 

[70herald]

Sounds as if 'sall good! I would have cautioned about the inner edges of the bell-housing casting: VERY sharp. You have already passed that stage tho.

That's a very good warning (ask me how I know /bcforum/images/%%GRAEMLIN_URL%%/smile.gif )

With what you've already accomplished, is there a compelling reason you've decided to NOT do the box rebuild yourself?

Mostly memories of a failed rebuild attempt on an MGB box years ago. I couldn't get the tolerances right no matter what I did, and every time I tightened the whole thing it would seize up. So I spend a bit of time and money and then had to send it out anyway. That's made me very gun shy.

Given that there were lots of metal bits in the oil, I would bet that some new gears will be needed. Once a few gears are needed it is not exactly economical to do the rebuild yourself unless you have a few extra boxes for spares.

putting the box back in is even more fun /bcforum/images/%%GRAEMLIN_URL%%/mad.gif to make it easier, get a long 5/16nf bolt ( at least 3 inch ) cut off the head and thread it into one of the gear box mounting holes on the top of the engine block. that way you can slide it on, and won't have to hold the weigh of the gbox while trying to get it lined up. Unfortunately, I only read this suggestion after I got the box back in.

 

[jdubois]

Thanks for the suggestion for getting the box lined up when I put it back on, I'll use that!

I noticed while inspecting things last night that the clutch slave cylinder leaks a bit, so since I'm in there I guess I better fix that. Anybody recommend rebuilding it, or should I just get a new one? I know it's easy to rebuild, but I'm afraid it'll just leak again afterwards.

I decided to replace all the clutch components, it's only $140 for the whole set. Also ordered a new pin and sleeve for the pivot, a new pilot bushing, a rebuild kit for the gearbox remote, and new rear mounts. I think I'm going to skip the flywheel replacement/resurfacing and drive shaft balancing / u-joint replacement. None of that really seemed to be causing trouble, and I gotta stop somewhere...

After I did all my inspection of various stuff last night, I began rebuilding the brakes. Boy, after just replacing the rear brakes on a '98 Dodge Dakota, the Spit's rear brakes are so easy it was a pleasure. Took me about ten minutes to do one side.

Oh, btw, people have had good things to say about Quantum Mechanics, right?!?!? I was just talking to the current owner of my last spitfire, who it turns out had just sent his tranny down to them earlier this year and who is having all kinds of problems with it now that it's back. I guess that could be a fluke, but it's making me nervous.

 

[kodanja]

Iv'e been dealing with John at Quantum Since the early 80's and have the highest reguard for his work!

BTW: he just installed my 5sp. Type9 in my TR6, works great!

 

[Andrew Mace]

I noticed while inspecting things last night that the clutch slave cylinder leaks a bit, so since I'm in there I guess I better fix that. Anybody recommend rebuilding it, or should I just get a new one? I know it's easy to rebuild, but I'm afraid it'll just leak again afterwards.

That's a fairly low-cost "gamble" if you will. Rebuild kits are pretty inexpensive. Disassemble the slave cylinder and look at the insides. If there's no scoring or pitting of the bore and no damage to the piston, odds are a rebuild will do you just fine. But while you're at it, check the clutch master as well. If you don't know when it was last done, rebuild (or, at worst, replace) it now and save yourself time and mess later!

 

[guzzul]

I noticed while inspecting things last night that the clutch slave cylinder leaks a bit, so since I'm in there I guess I better fix that. Anybody recommend rebuilding it, or should I just get a new one?

I agree with Andy, just open up the slave and check carefully for pitting. The slave seems to have more or a tendency to get water in it than the MC, just location maybe. If the bore is clean, rebuilding should be ok.

Also ordered a new pin and sleeve for the pivot, a new pilot bushing, a rebuild kit for the gearbox remote, and new rear mounts.

Did you get the bronze bushings for the bell housing? Have you checked them? If the pin has noticeable wear marks in it, then the bushings will probably be worn too. They are quite easy to drive out of the bell housing, just push them out and have a look at them, see if one side of the bush is wearing thinner than the other. This is also a source of wiggle in that pin. Bushings are cheap (about $3 at Spitbits) and easy to refit, they just push back in.