Shimming cow horns

[Erich]

On my 1930 Ulster Rep(not built by me) I have found that the bonnet and side panels don't properly line up. By shimming the cowl up 3/16", I can get everything to line up well. I intend to place shims between the cow horns and the forged bit at the front of the chassis. My questions are: 1. Is/are there any potential issues with doing this? The engine is not presently fitted. 2. Is this something that others have found necessary? 3. What size are the bolts that should be used? I know BSF, I think 3/8. Hardened? And where can I source ones that are 3/16" longer and not threaded for the top inch to the head? If it makes a difference, my cow horns are cast aluminum and Have been told they are reproductions.


Erich in Seattle

[Howard Wright]

Hi Eric

I'm not familiar with the body mounts for Ulsters (real or reps) but I would have thought that you could pack the mounting points at the rear of the car thus tilting the bulkhead forward and making up any gaps in the bonnet fitting.  I have had to do this on my 1936 special and my 1930 RK. I used quite thick rubber washers which also tend to help with vibration.

There are many suppliers in the UK selling BSF set screws of varying lengths and it is quite easy to shorten them if you buy ones that are too long.  Most if not all are high yield and a fair proportion zinc plated.

Cheers

Howard

[Ruairidh Dunford]

I had terrible trouble with the aluminium cow horns snapping on my own Ulster so changed to original type, no problems since.

[Chris KC]

The thing I would say Erich is however you get there, the fixings must not put the aluminium body panels under stress, or they will eventually fail. I've recently replaced my n/s panel as the holes pulled out completely, and bonded reinforcement into the o/s panel which was heading the same way. A patch of local reinforcement does no harm here or failing that use large flat washers.

["Slack Alice" Simon]

I second the thought that there should be no stress at all on the panels.

Not that I have an Ulster.

Also, on my special, I have a thin rubber washer wherever possible on each side of the panel.

It helps with absorbing the flexing, it stops (slows down) the panel being fretted through, and helps slow electrolytic action.

I didn't think to use a washer between sidelights and mudguard (fender).

When I finally removed the sidelights, the small steel cones between light body and mudguard were full of corrosion products, and there were neat holes the size of the cone bases eaten through the 'guards.

The result of 20 years or so of electrolytic action.

Simon

[Robert Leigh]

Ruairidh's comment about the aluminium cow horns confirms that they are not suitable. My car has steel ones made for the purpose. If you can get suitable steel bent to shape by your local blacksmith, or do it yourself if you have a suitable source of heat. This will allow you to drill the holes exactly where you need them, and you can shape the edges to something like the originals if you are fussy about them looking absolutely right.
Robert Leigh

[Erich]

Hi All,

Thank you all for the comments. The impression I get, is that however I get the panels and bonnet to fit is fine. In answer to Howard's post, the rear of the side panels has a curve and it I were raise the rear of the body, the side panel fit might be improved, but I would still have a bonnet front fit issue. The flitch panels would also have a fit issue and the rear. One issue is that on this CC body, the side panel dimensions, top to bottom, is almost 1/4" different between near side and off side. My alloy horns will not be under stress and the curve is actually good. It is the height that is the issue.

Erich in Seattle

[Chris KC]

Erich, I think you will find those side panels are generally supplied oversize and they are fitted to the car. Thus some irregularities are to be expected. When 'repairing' mine I got a local metalworking shop to knock up a new nearside panel for me (quite inexpensive) but I allowed a bit of extra metal on the ends so I could trim it to fit.

[Erich]

Hi Chris,

My side panels were obviously trimmed for length by the fellow that put the car together. I've had to have material added at the front and rear of the bonnet. Given the skill level of the fellow who built the car, I don't think he could have shortened them top to bottom as the folds are quite well done. Raising the cowl 3?16" by shimming the cow horn fixing on the chassis, should make it much better than it was.

Erich in Seattle

[Erich]

After a conversation today, I realized what the issue is with shimming the cow horns...the starter handle will no longer fit through the hole in the cowl. Duh!

Erich in Seattle