Spitfire Spitfire Gearbox Removal

My 79 1500 is off the road for the winter and to take care of a loud grind/whining sound on engine braking or overrun. I am not sure whether it's a problem with the gearbox, clutch or even the slave cylinder. So I think my first course of action is going to be to remove the transmission tunnel/cover and go from there.
Easiest thing first, so I'll probably rebuild the slave cylinder, reinstall and try driving the car to see if it made any change to the noise. If not I'll keep going and remove the gearbox; with it out hopefully I'll be able to find the source of my noise.

Problem is I've never done this before so I am not sure where to start. Anyone have a decent guide to reference for pulling the gearbox?

I have not seen an online guide. Maybe there is a YouTube video or similar. Failing that, I'll describe what I do. Forgive me, I'm sure I'll miss some steps.

• Remove the center dash support and radio if fitted.
• Remove the front seats, and peel back the carpet.
• Remove the screws holding the tunnel to the car body.
• Remove the gear shift knob and pull the lever back into 2nd or 4th.
• Pull the tunnel cover back, up the shift lever, and remove it from the car.
• Jack up one rear wheel and place the car in neutral.
• Undo the four bolts holding the driveshaft to the gearbox. Turn the elevated rear wheel as necessary to gain access to all four driveshaft bolts.
• Remove the two nuts holding the rear gearbox mounts to the yoke attached to the car body.
• Mark and undo the wires for the reverse light switch and pull the wires up into the engine bay out of harm's way.
• Undo the two bolts holding the slave cylinder bracket to the bell housing. Pull the slave back and over to the side. Tie it out of the way.
• Place a block of wood on a floor jack and position it under the rear of the engine oil pan.
• Raise the jack just enough to start to lift the tail of the gearbox a tiny bit.
• Undo and remove all the bolts and nuts holding the bell housing to the engine back plate.

You can continue by yourself if you are confident and capable. A helper now would be best.

• Raise the jack under the engine until the gearbox rear flange is slightly higher than the driveshaft flange so they won't hit each other.
• From inside the car place a piece of 1x4 about 2 feet long between the cast iron body of the gearbox housing and the frame rail.
• Apply downward force on the 1x4 to take the weight of the gearbox a bit.
• While holding force on the 1x4 (and pushing it forward slightly) wiggle the gearbox tail as you pull the transmission backwards.
• With a little effort the gearbox will come off its dowels. Keep supporting it with the 1x4.
• Pull the gearbox backwards, rotating it 90 degrees or so as needed to free its input shaft from the clutch.
• Continue pulling backwards and rotating as necessary as the gearbox moves into the passenger compartment. (Rotation will help the bellhousing clear the underneath side of the dash).
• From there you will be able to muscle the gearbox out of the car.

Putting it back in is largely "reversal of the above (quoting Haynes)". However, if you remove the clutch components you will need to re-center the clutch on the flywheel first. When pushing the gearbox back onto the engine backplate you will need to turn the rear flange of the gearbox a bit so the gearbox input splines line up with and enter the clutch splines. Once the gearbox appears to be started on the dowels and studs you will need to fit at least a few of the bellhousing bolts to secure the gearbox prior to fitting the remaining bolts. This is another part of the process where a helper is a good idea.

Sorry I don't have pictures of this for you.

Wow, that's great, exactly what I needed. Thank you very much.
I don't have a shop manual for this Spitfire, but I am thinking it might be a good idea to invest in one for this job.

Firm, good advise and the manual will be the best thing. You will be able to see the parts that are hidden and you won't be surprised when they appear.
Get that battery disconnected first. The two nuts behind the radio panel at the top are a pain.
When putting it back, getting the bolts lined up for the dash support, with the carpet in the way will be much easier if you glue the carpet in place and have a small bottle jack with a piece of wood on it, this would be to jack the dash up while sliding the support in, don't over jack it, just enough to get it in. Oh, the holes for those four lower bolts should be tapped and a little oil in the holes will make your life a lot easier also.

Wayne

Excellent advice on jacking the dash up a bit. Getting that center support in place is one of the more frustrating parts of the job. I use a bit of anti-seize on those screw threads. Oil or grease would also help.

Thanks guys.
I assume that the handbrake lever and the soft armrest behind it don't need to be touched?

Firm, Don't even think about pulling that bolt out of the hand brake, unless you have a day to waste getting it back in. No on that part being removed.


Wayne

Thanks, I won't touch and handbrake!

I took a look inside the car tonight around the trans tunnel just assessing what would need to be done to remove the gearbox and I came up with one question...Where does the H-support connect to the dash up top? It's hard for me to see with the radio in place, but I can't see any bolts holding it to the dash, where are they?

Above the radio and tucked under the lower edge of the center dash section you will find two 1/4" bolts. They go through the dash support, the metal edge of the dash and stiffening brackets that support the dash.

Ok, update time.

I got the rear of the car up on stands and checked everything I could think of while under there. U-joints all look good, no signs of play or wear. Closely inspected the driveshaft and I don't see any signs of rubbing on anything. Everything seems tight and in pretty good under under there.

I moved onto the inside of the car and pulled out the transmission tunnel. Clearly someone has been here before as some fasteners were missing and the tunnel was sealed into place with silicone. It came out pretty easy and now that I can see everything I feel more comfortable with the idea of pulling the trans if I have to.

Before I take it any further apart though I am going to try driving it with the tunnel off to see if I can isolate the noise. Actually, I am going to get someone else to drive and I am going to ride shotgun with an automtoive stethoscope so I can try to pinpoint the noise. Unfortunately it's really wet and nasty outside today, so my little trial is going to have to wait for a dry day

Lastly, I noticed two holes at the top of the bellhousing with no fasteners in them....are they missing? Or are those holes just not used in this application?

Firm, the one on the left needs a stud installed and a nut put on. The other is a blank for a guide pin. Pull out on stud to get the size.

Wayne

Merry Christmas !

As Wayne said, the top bellhousing hole with the spotface around it is for a threaded stud. The other hole is for one of the dowels I mentioned earlier. It is for alignment of the components. There will be another dowel "down low" somewhere.

All the fasteners (excluding the starter motor bolts) holding the bell housing to the back plate are 5/16-24 (UNF... fine). You may not find a stud that size at the local parts store. However, they are nothing special. You can replace the stud with a bolt if you want to. Or... you can buy a 5/16 fine thread bolt with LOTS of thread and cut it off to make your own stud.

Driving with the tunnel cover is not a pleasant experience. Keep your hands/hair/clothes away from the driveshaft flange.

The one with the shoulder is missing the stud, nut, and washer. I'm going back 45 years to the last time I did a Spit transmission but I think the other hole is for a location dowel. Your description of the noise sounds like a transmission going BUT, just for fun, check the engine mounts. If the rubber is gone, the metal-to-metal can be noisy. Good luck.
Dave

Had a good dry day today so I took it out on the road. With my brother driving I sat on the passengers side with an stethoscope trying to distinguish whether the noise was coming more from the bell housing (clutch) area or from the gearbox itself. Turned out to be very difficult because the noise travels through both sections - but to the best of my ability I think it was a little louder in the gearbox. It is definitely coming from this area though and not anything further back.

I then took the top cover off the the box and peaked inside. To my untrained eye everything looked pretty nice - clean and no obvious defects on the gears. The was one gear, a smaller one on a lower shaft (layshaft?) right at the back (towards the back of the car) that seemed to have about 1/16 of an inch worth of play in it if I moved it with a screwdriver....Not sure whether that's normal or what, it might even be the reverse gear (looking at exploded view)?

Anyway, I think the next step is to pull it. I'll get myself familiar with the procedure and then maybe attempt next week. My current plan is to replace any clutch components that look suspect and swap in a used gearbox I found locally. I assume a gearbox from a 76 Spitfire would be a direct fit?

as long as they are both the same spline number your ok. both should be 20 splines

Firm, that would be the reverse idler gear that is moving at the back of the transmission on the side, kind of like a leaver. These trannys have a "C" clip near the front on the main shaft that will break and lets the gears float on the shaft and make a lot of noise. The needle bearings in the lay shaft along with the brass bushing on each end of it are bad to go out.
Hope the new (used) one is better.

Wayne

Thanks Gents.
Yes, I hope the used one is better as well. Owner says it was working (and sounding) fine when the car came off the road, it's a lower (50,000) mile female owned/driven car that's being parted out due to rust over taking. For what it's worth I am gunna try it and hope for the best....Worst case if the new one turns out to be bad I'll have to get my original one rebuilt and swap again.

Though I did not follow this advice when it was given to me... I will forward it to you.

The laygear needle bearings do tend to wear on the shaft. Even if you were told the donor box was in great shape when removed, you may want to disassemble the box enough to put in a new shaft and bearings. The needle bearings are not cheap but pulling the gearbox again in a month or so won't make you happy either. Again, I did not follow this advice and our donor gearbox was fine... but you never know.

The splines on the donor box will be the same as the ones on your car. The earlier Spitfires had a different gearbox that used several different components in the drivetrain. As long as you get a single-rail box that looks like the one in the picture you posted earlier it will fit with what you have. The only exception being that the overdrive gearboxes require different rear mounts and driveshafts. Again, make sure the donor box looks outwardly like yours and you will be fine.

k, so today was a big day...my first Transmission pull.

Working in a freezing cold garage didn't help, but I followed DK's instructions and everything went really smooth. Got everything unbolted and ready, then my dad and brother came by to help lift the unit out of the car. Once we had the engine jacked up enough for the back end of the transmission to clear the driveshaft tunnel it was pretty easy to get out.
Removed the clutch and noticed that the pilot bushing was really loose in it's hole so I also removed the flywheel so I can replace the pilot bushing while I am here.

I have a few questions I am looking for some help with for the next steps...

1. There is quite a bit (maybe a 1/16th of an inch) of play in the transmission input shaft...both if wiggled in and out and up and down. I assume this is not normal and likely a cause of my noise? I haven't yet picked up my replacement transmission (looks like I'll get it Sunday) so I have nothing to compare it against.

2. As I mentioned, the pilot bushing was really loose in it's housing, I assume it's actually supposed to be a very tight fit?

3. When I do get my replacement (used) transmission I'd like to flush it out before putting in fresh oil and installing - what's the best way to flush it?

4. How do I remove the release bearing from the lever? I can see two little black clips, is that it? Or it is pressed into the housing as well?

5. Lastly, this broken piece of something was held to the rear (exterior face side) of the engine block by the two bottom right bellhousing bolts...Any ideas what it's from? I looked like it's been there a long time and clearly wasn't doing anything....

Firm, That "C" clip may be the problem, The pilot bushing reamed out may be the cage bushing at the back of the input shaft going bad, because of the clip. That junk looks like a mount of some kind. There is a dust cover that should be on the bottom plate to keep out road kill, OH, and dirt, maybe that's all that is left, just hard to tell until you get it apart. Let me know what you find.

Wayne