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TC Bonnet Realignment "In Situ"
Posted: Wed Mar 27, 2024 12:45 pm
by rstarkweather
I have read Mike Sherrell's excellent write-up on aligning the bonnet when rebuilding the tub. My question to the group is are there "tips and tricks" for realigning a bonnet on an assembled car?
I am currently in the market for a TC, and on one of the cars I am considering the bonnet top at the rear seems to be about 1/4 inch too low, i.e., below the scuttle top (this is based on looking at a photo not actually measuring the car) and the bonnet side hinge line is about 1/4 inch below the scuttle-top bottom line ("body line" on the side of the scuttle).
The front edge of the bonnet seems fairly well aligned with the radiator shell.
Thought? Ideas?
Re: TC Bonnet Realignment "In Situ"
Posted: Wed Mar 27, 2024 1:19 pm
by Steve Simmons
It might just be a matter of worn or incorrect rubber at the rear. If this is the case, I would expect the front and rear lines to both be wider at the top, and possibly overlapping the lower front corners with the grill shell.
Re: TC Bonnet Realignment "In Situ"
Posted: Wed Mar 27, 2024 1:44 pm
by Ray White
Has the car had a new body tub at some time? When I fitted my new body, the bonnet needed trimming. Also, my car had suffered a trauma at some time(pre 1960)and what was done back then is anyone's guess.
Re: TC Bonnet Realignment "In Situ"
Posted: Wed Mar 27, 2024 2:30 pm
by robj
I'm not quite there yet but I've read TCF and TCF More until I think I about have it memorized.
I think I've read in more than one place the bonnet was "fitted" to each individual car. If a replacement bonnet was sourced or a new tub built without the benefit of the bonnet in place there's a good chance the fit will be poor.
Also read somewhere there was a worker on the assembly line who's job was to trim the newly painted bonnet with snips to get the correct fit.
That may be a tall tale... but then again?
robj
Re: TC Bonnet Realignment "In Situ"
Posted: Wed Mar 27, 2024 5:27 pm
by Tom Wilson
Hello Rob - here's a note about bonnet fitting from your "resident historian" . . .
Yes, side bonnet panels were often trimmed on the production line. This actually started with the building of the vintage MGs - the 14/40, 18/80, and the first Midget, the M type in 1929.
Prewar, and for the first several hundred TCs (1945 through early 1946), side panels were fitted in primed only state. Chassis numbers were stamped (MMM cars on the chrome center bonnet hinge), early TCs in the front bottom corners of the side panel. Then they were sent to the paint department for their final color painting, and delivered to the finishing department to be permanently installed on the car.
Here's the manufacturing process they used for our TCs:
The top bonnet panels were always a fixed length, for all models. The side panels were made a bit long at the front edge.
Bonnets were installed near the end of the body track (production section where body was installed and everything put on it). Center hinge installed onto the 2 top panels on a special sawhorse buck at the side, then that unit was installed on the TC. Radiator stay rods were adjusted if needed for a good fit.
Next step was to measure side bonnet panel length. An H shaped wood jig was used for this. Back leg set on the body rubber, front leg (legs connected by a center arm) adjusted to needed length and angle to fit the radiator shell just right. This jig was taken to a side table and laid on the bonnet panel with the back leg justified to the back edge of the panel. Then a scribe mark was made down the front leg, noting the trim cut line. If a lot of material needed to be removed, a Do-All vertical metal band saw or tin snips were used. If only a little bit, a rasp file was used.
Next step was to stamp the cutouts for the rubber panel buffers on the front bottom corners of the panels. This was done with a fly press at this point of the body track.
Then the panel was installed on the car - the brass hinge rod connecting the top and side panel. If further trimming was needed, it was done while panels were still on the car with a rasp.
As noted earlier, the early TCs had those panels then removed, chassis numbers stamped on the bonnet corners, sent to the paint shop for painting, then returned to the cars for reinstallation in the finishing department, when rubber corner panel buffers were installed. That turned out to be too cumbersome a process for the planned production volume, so the switch was made to just run a small paint brush of correct color paint down that front edge. The rubber buffers were installed at the same time.
All of this isn't conjecture - there is a fair amount of description of the process from MG production line workers of the time, and I have personally discussed it with two of them who were quite exact and descriptive of the process. Interesting that a detail like that was etched in their memories. There are also several period factory photos showing some of these steps.
And - if you're looking for a "spot on perfect" TC, freshly restored, that you don't have to be concerned about reliability with, I've finished the restorations of TC0279 and TC2040. Likely that one will need to find a new home within the next 12 months, as space here is limited.
Safety Fast,
Re: TC Bonnet Realignment "In Situ"
Posted: Fri Mar 29, 2024 10:10 am
by BCBryan
I'm currently doing the test fit of my hood to TC 6984 as part of my complete restoration which included new tub wood. I had done one test fit earlier before fitting the doors and doing final adjustments to the tub to frame mounting points.
For this fit I installed the new rubber welting along the grill shell and used the old body tub to hood rubber.
I started with just the hood top as in the photo and found that I need to mover the rad/grill back a bit on one side and forward a bit on the other side. When I added the hood sides they aligned perfectly. I was very pleased!
This was bought as a complete car, having not been restored before but driven hard and run on a small budget. So not the same as a made up car which might have more fit issues.
Hope this helps.
BCBryan.
Re: TC Bonnet Realignment "In Situ"
Posted: Sun Mar 31, 2024 8:27 am
by rstarkweather
Thank you to everyone for the posts. Obviously, the first step is a more thorough examination of the car.
But I think removing the existing rubber rest, and then adding a scuttle-width strip of wood on top of the "outer scuttle wood" (as shown on page 188 of TCs Forever), might raise up the trailing edge of the bonnet enough to sort out the misalignment. Then I can refit the rubber rest.