Bonnet (hood) Fitting

[SteveW]

So the new season of me trying to do a full restoration of my TC has commenced (progress is about as rapid as on 'The Curse of Oak Island'!). I'm at the stage where I have to trial fit the bonnet (hood) before fixing the scuttle top in place, so I have mounted the radiator and grill. In short, the bonnet does not seem to fit, so I am hoping that the folk on here will have some advice:

The first problem is the there is no way for the bottom edge of the scuttle top and bonnet hinge to line up. TCFE says that there should be a smooth line going from one to the other. This is how mine looks (first picture) - there is about a 1/4" step between the two. This is completedy unfixable as it's to do with the dimensions of each, both of which are original as far as I know. Is this a normal degree of difference from the ideal or do I need a different scuttle top or bonnet?

Second problem (second picture) is that the edge of the lower section of the bonnet does not line up with the tub. I've checked the measurements of the tub and they are correct (if anything, the angle of the front of my tub is a little steeper that it says in Sherrell's book, which should make the fit better, not worse). At this angle, the leading edge of the lower bonnet section is vertical (as it should be). The only way to correct the gap shown in the picture would be to drop the radiator by about 3/4", but I don't think that it's even possible to lower it that much (I could drop it a bit and raise the tub a bit). Also, at the moment, with the chassis level, the top of the bonnet is also level (horizontal). If I lower the radiator then the bonnet will dip down towards the front and also the leading edge of the lower bonnet section will no longer be vertical. With the chassis level, Should the top of the bonnet be horizontal or should it slope slightly towards the front?

The only solution that I can see at the moment is to weld a sliver of extra metal to the lower bonnet section to close the gap, but that should not be necessary. Also, it would mean that the vent slats are no longer parallel with the leading edge of the tub. If I raise the tub and lower the radiator, then I will have to weld metal to the front end of the lower bonnet section to bring it back to vertical - again, with original parts, this should not be necessary

Any suggestions or observations? If I'm doing something dumb, what is it?

Steve

[Marv]

I believe I've read a similar issue in the past and one item of mention was that the bottom Radiator support bar can be mounted wrong way round and satisfied that chaps problems. Might be worth a look.

[Steve Simmons]

Was the bonnet original to this car? They were hand fit on the assembly line with a big set of metal shears!

[SteveW]

Well, it was with the car when I bought it, but the previous owner bought it in bits and reassembled it to sell, so who knows?

If they were cut to fit on the assembly line, I don't feel too bad about potentially having to do some welding to get the lower section to the right angle to match the tub, but I'm at a loss as to what to do about the line between the scuttle top and the bonnet hinge.

[Steve Simmons]

I'm no expert on body panel fitting, but it seems if you can lower the front of the bonnet then the rear line will close up. Whether that means lowering the entire radiator or manipulating the mounting points, or maybe both. Also measure the radiator core and make sure it's the right size. I've seen cores that were made too tall, yet still fit inside the shell.

[SteveW]

Hi Steve, you are right, lowering the front of the bonnet would close the gap a bit. Before I start to mess with the height, could someone confirm whether or not the top of the bonnet should be horizontal if the chassis is also horizontal.

As regards the line from the scuttle top, I think that my only option is to cut the upper bonnet along its full length and weld in more metal in order to drop the hinge line. It's a big job unless someone can see an alternative.

[Duncan M]

Raising the front part of the cockpit would also lessen the gap. Does not mean that is what you should do. Curious if the bonnet panel (vertical, at area in question) is a straight line or a gentle outward curve? Originally that piece had a gentle curve, to meld the visual lines of the car better. Many restorations have lost that.

I don't think these cars were nearly as "hand fitted" as popular myth would imply, and some cars simply had better panel fit than others. Sherrell's first book gives instruction on how to take advantage of all the adjustment points that are there. Points the factory would have been expert in taking advantage of.

[Herman 5560]

Shout if there are any specific measurements you need. My hood is not fitted at the moment and it will be some time before I get there, but scuttle and grill is fitted because I had to make the stays for the radiator.

[Herman 5560]

Hood fitment.JPG (77.29 KiB) Viewed 7120 times

Found this in the book on adjustment points

[SteveW]

Hi Herman,

I have that fitting guide that you have copied for me, but thanks anyway. There are a couple of measurments that I would be grateful if you could take for me: i) The length of the rear edge of the upper bonnet pieces (i.e, where it meets the scuttle top). ii) the length of the front edge of the scuttle top where it meets the bonnet. Basically, I'm trying to work out if the bonnet is not big enough (i.e. the hinge line should be lower down the side of the car) or if the scuttle top is too big and therefore its edge is too far down the side of the car. This will dictate whether I cut and weld the bonnet or cut and weld the scuttle top. No amount of adjusting the tub or radiator shell will bring these into line as it is as one is longer (or shorter) than the other.

As regards where the lower bonnet section meets the tub, I'm going to make some further adjustments today by raising the tub - more at the front than the back as this will change the angle a little and also by lowering the radiator shell. I guess that I can also take out a couple of mm of the discrepancy by how I fit the rubber. Mike Sherrells book does say that the bonnet should be horizontal, but I'm going to have to compromise on that a little. Hopefully by adjusting everywhere possible it will not be too far out of factory spec in any one place.

[Herman 5560]

Scuttle over the top joing line to joining line.

From Scuttle joining line to bottom of tub

Actual measurement

tub Bottom 2 M.jpg (27.19 KiB) Viewed 7107 times

Top Bonnet Rear edge

Actual measurement

[Herman 5560]

Bonnet Side

Actual measurement

[SteveW]

Hi Herman, Thanks for the measurements. Chris Blood also took some measurements for me and both you and he agree on the total length across the scuttle edge (43"). However, I notice that if you double the length of the edge of your upper bonnet, you get a number that is larger than this so does this mean that your hinges and scuttle edge don't line up either, but in the opposite sense to mine (i.e. is your bonnet too long?). My bonnet is the same size as Chris' so I've concluded that I don't need to cut it. This means that it's the scuttle on mine that's wrong as it's longer at about 43 1/2" than both yours and Chris' - i.e. 1/4" per side.

When I look at finished cars on-line I can see quite a few where the hinge line and scuttle line don't match, so maybe there was a whole batch of them that were wrong? I want mine to line up so I think that I am going to have to rework the edge of the scuttle as shown in the following picture. As you can see, this will make the bonnet flow nicely into the scuttle top. The pencil line starts at 1/4" and then tapers to zero. It should be simple to trim the metal whilst leaving enough to make a fold. I'm going to test fit the windscreen frame bracket first though to make sure that it will still look right.

Before I commit to the cutting tools, can anyone see anything wrong with this strategy? It's one of the few places on the car where 1/4" can make a significant and obvious difference

[Herman 5560]

No idea about ligning up. Never paid any attention to it when the car was assembled and now it is all in pieces.

Have you got your scuttle/bonnet rubber fitted?

[SteveW]

I've not fitted the rubber yet but I have made allowances for fitting it when measuring up. I've also manually held it in place to assess the gap required and I have put little spacers between the wood and the bonnet to simulate the thickness of the rubber.

As you can see from my last picture, the bonnet fits the profile of the scuttle very well, it;s just that it stops short of the bottom edge of the scuttle by 1/4", hence my option to modify the scuttle by that amount (it's certainly a whole lot easier than modifying the bonnet!).

[Herman 5560]

You have me now so curious I am tempted to fit the bonnet top pieces

[Mark McCombs]

I think the front top rail (bonnet resting strip) can be lowered to allow the hinge line to go down, to get a closer alignment to the scuttle line, correct? My original 'bonnet resting strips' have larger (1/2"?) holes than the scuttle bolts to allow for that.

[Tom Wilson]

Don't know if it will help but check the angle of the back edge of the bonnet and the front of the scuttle. Both should optimally be 15° (75°) relative to the level plane of the chassis. Radiator should be 90° to the chassis, and the side bonnet hinge line should be parallel to the chassis. Hard to achieve unless you are building from scratch as I am on two tubs right now.

Tom Wilson

Also - a historical look:

For an interesting read, this is the process used on the body track (2nd section of the TC production line) for fitting bonnets:

Bonnets were installed near the end of the body track, the 3rd station from the end. Cyril Polley and Maggie Buckle did this job through TC production (and most of TD as well).

• Radiator stays were already set close to final position to make the back edge of the radiator shell vertical.
  Center bonnet hinge installed on top two panels.
  Top bonnet panels placed onto the car to check fit. Fine tune radiator stays and lock into position.
  A jig was places in the location of the side bonnet panel on each side. This was in the shape of an H, with the front and back adjustable in length and angle. The rear leg of this was typically locked into place at the correct 15° angle, and the front was adjusted for an optimum fit to the radiator shell.
  The jig was removed and placed onto the car's side bonnet panel on a bench next to the line. If the panel needed to be trimmed a line was scored with an awl across the edge of the jig. Panel was then trimmed - either with tin snips or the Do-All machine (a vertical metal cutting bandsaw).
  Front bottom corners of the side bonnet panels were stamped with a flypress to cut the notches for the rubber buffers to fit into.
  Brass hinge rods were installed. I think the top panels were removed and taken to a custom sized buck to hold all 4 panels so the rods could be inserted.
  Bonnet latches installed on the side panels.
  Bonnet assembly placed back on the car and fit for the side panels rechecked. A file and/or tin snips used to fine tune fit if needed.
  Center hinge caps on both ends installed.
  Bonnet corner buffers installed.
  Raw edges of bonnets painted - a small paintbrush with a can of paint in hand was the process. Sometimes done on the track at the station, sometimes done in the next department (finishing).

The process of fitting bonnets like this started with the M and F types (and perhaps the Vintage models as well) and continued through the TD and Y types. With increasing volume the speed and efficiency of the process was modified, but basically stayed the same.

Early TCs (and perhaps prewar T series) bonnet side panels were in primer when fitted on the line. The chassis number was stamped in the front bottom corner (under where the buffer fit), the panels sent to the paint shop for painting, and then returned to the car for final installation in the finishing department. That was eliminated for efficiency with the front edges hand painted on the line. MMM cars (D, F, J, K, L, N, P) had the chassis numbers and color code stamped on the center bonnet hinge on the line. They were in primer when fitted, then off to the paint shop and back to finishing for final installation.

[Mark McCombs]

Also, Important: I too had that subtle 'curve' at the rear of the bonnet edge and was thinking the same as you, cursing the previous fellow that trimmed it that way.

BUT:

AS Duncan noted above, Its suppose to look like that. Its for the side view illusion of the car.
Just align the finishing rubber to match that curve when nailing it on.
Relieved? I sure was!

[Mark Strang]

Steve,

I had a recent problem on TC 7801 with the scuttle that you have relative to the scuttle and bonnet line. Mine was off about the same amount. Interestingly a friend with a TC has the same problem as both of us and his car is all original also. The passenger side is fine with a smooth line from the bonnet to the scuttle. He doesn't care. I do.
I taped a line from the bonnet hinge line to door opening as you have shown, to establish the desired shape. Then I took a cut off wheel and cut the scuttle to the line so the "flow" was smooth. I then tucked a thin piece of copper between the scuttle and the quarter panel and tack welded the bottom edge of the scuttie. There is apparently a piece of metal on the scuttle that is folded over where it attaches to the quarter panel. After that I ground it back down so now I have a smooth line from the front to the rear. Awful to have to do that, but it was the only way to get things lined up properly.
I wouldn't hesitate to weld a strip on the bonnet to make up the space. No one will ever know and it is the only real practical way to handle the issue. The radiator adjustment is not a practical fix. I'd be curious to see if the bonnet latches line up. You might have to alter these as well. Hope this makes sense.