Aftermarket bonnet - Help please!

[mikealdren]

I swapped my old bonnet with a bulge for an aftermarket flat bonnet. Now, sometime later, I've tried fitting it!

The fit isn't great and the tubular steel support is an awful fit, it's too long so it's been fitted some way from the front edge of the bonnet to the rear of the mounting bolts. There's no way I can use the centre adjustment to alter the line of the front of the bonnet.

I suppose the easy answer it to cut it and re-weld the tube but a new bonnet is not too dear. Does anyone have any spares?

[mikealdren]

I've tried SJ Sportscars who list the bonnet in their catalogue and also the front bar. I spoke to Steve and he is getting a batch of bars made up in a month. He also has bonnets which are sold without metalwork.

[elanner]

On this topic I've often wondered how to get a flat bonnet for my Elan, which has a bonnet bulge and Webers. Shipping one from the UK would probably be a nuisance/expensive (especially if it then didn't fit well).

Does anybody have experience cutting the bulge out and glassing the hole to make a flat bonnet? It seems like it would be quite straightforward. But any flaws would be painfully visible and I'm not the world's fibreglass expert....

Nick

[Foxie]

I swapped my old bonnet with a bulge for an aftermarket flat bonnet. Now, sometime later, I've tried fitting it!

The fit isn't great and the tubular steel support is an awful fit, it's too long so it's been fitted some way from the front edge of the bonnet to the rear of the mounting bolts. There's no way I can use the centre adjustment to alter the line of the front of the bonnet.

I suppose the easy answer it to cut it and re-weld the tube but a new bonnet is not too dear. Does anyone have any spares?

Could you post a pic, I'm finding it difficult to visualize what the problem is.

What is the centre adjustment you mention ?

[mikealdren]

Here it is:

The problems is that the tubular bar is too long so it won't go between the bobbins and close enough to the front edge. In a previous life, it was riveted where it is loosely shown in the photo

I've now tried the bonnet off my other plus 2 130/5 and that has a much shorter front bar.

The adjustment I and referring to is the small bracket off the front of the bar which can be adjusted to abut to the front fibreglass of the bonnet to stop it sagging.

I think I'll cut the bar off, shorten it and get it welded back, if that fails I'll buy a replacement bar from SJ Sportscars
when they become available.

The next challenge is getting the bonnet to fit accurately to the profile of the front wings and fitting new bobbins into the bodywork. Neither bonnet fits very well! Has anyone tried altering the curve of the rear end of the bonnet by adjusting the bolts on the reinforcing bar?

[stuart]

hi
I have a flat original + 2 bonnet for sale on ebay at the moment

regards
stuart

[gjz30075]

Does anybody have experience cutting the bulge out and glassing the hole to make a flat bonnet?

Nick

Nick I had the same concept done, ie, the bulge on my Sprint was poorly repaired before I got the car so
I bought an aftermarket bulged bonnet for the proper bulge. The best fiberglass guy I know told me
it will show the mating lines after a short time after it's 'glassed in. I decided to have it done anyway, by
a different guy and, yes, after a few years, in the right light, the repair lines are showing up.

[elanner]

Thanks Greg. I guess I'm not surprised.

Why didn't you simply use the aftermarket bonnet complete, rather than transferring the bulge?

Perhaps, after removing the bulge and filling the resulting hole, the final step would be to put a veil layer over the entire bonnet? That could cover a multitude of sins.

Nick

[gjz30075]

Nick, the whole bonnet was terrible. No 'glassed in conduit, no hook, the 'rockers' weren't positioned
good and it was pretty flimsy. But the bulge was the correct shape.

Yes, maybe the veil would have covered the seams better. It was explained to me that the new
fiberglass would shrink, whereas the 'seasoned' fiberglass would not.

[Foxie]

Here it is:

The problems is that the tubular bar is too long so it won't go between the bobbins and close enough to the front edge. In a previous life, it was riveted where it is loosely shown in the photo

I've now tried the bonnet off my other plus 2 130/5 and that has a much shorter front bar.

The adjustment I and referring to is the small bracket off the front of the bar which can be adjusted to abut to the front fibreglass of the bonnet to stop it sagging.

I think I'll cut the bar off, shorten it and get it welded back, if that fails I'll buy a replacement bar from SJ Sportscars
when they become available.

The next challenge is getting the bonnet to fit accurately to the profile of the front wings and fitting new bobbins into the bodywork. Neither bonnet fits very well! Has anyone tried altering the curve of the rear end of the bonnet by adjusting the bolts on the reinforcing bar?

Yes, I can see it now !

Several problems here.

First of all, whoever fabricated the front bar ( tube ) assembly seems to have had no idea what its function(s) are relative to the bonnet design.

The side strips reinforce the side flanges, but also serve to support the front pivots bolts, avoiding a "single shear" mode of support. ( Which is probably why you need to repair the bobbins ! ) See pic.

The main function is of course to strengthen and support the bonnet across its full width.

The "adjustment" bar you mention is not an "adjustment" bar. It was meant to attach a pair of springs which would assist the bonnet lifting, see drawing. As such, the end of the bar would need to be located in front of the pivot axis, and as far forward as possible in order to maximize the leverage.

IMHO the bonnet is light enough not to need spring assistance !

To get the curve of the bonnet front right, I used a small timber block with a semicircular cut-out to sit between the tube and the bonnet, and a small timber wedge glued in place. See pic.

I moved the bar( tube ) on my bonnet to a position to the rear of the pivots in order to allow the front of the bonnet to clear the top of my dry sump oil tank. I also had to cut away a section of the front flange. I found it easier to braze rather than weld the tube, it's quite thin walled.

Another thing I did was to replace the nut on the pin at the top end of the bonnet strut with a small spring locking pin.

I made up a spring bolt to replace the rhs pivot pin. See pics. I still have normal bonnet operation using the locking strut, but I can also now remove the complete bonnet in less than 20 seconds.

Regarding the mating of the rear end of the bonnet with the scuttle, I did not refit the reinforcing bar with the bonnet catches. What I did was cut a couple of small "vees" in the rear flange, and refibreglass the flange with the correct curvature, using a temporary timber supporting cross bar and wedges.

[mikealdren]

Hi Foxie,
many thanks for your considered reply.

I like your idea of the wooden block, I'll try that.

The adjustment bar was indeed used for the spring (attached to the rack I think) on early cars but on my later car it abuts the front of the bonnet and I had been led to believe that this was intentional. It certainly wasn't to attached the spring and I suspect that Lotus would have deleted it if it was not otherwise required. The original bonnet is indeed light enough to not require the spring and Lotus recommend cutting the slots in the trailing edge of the bonnet to assist opening as on later cars. Aftermarket bonnets seem not to have this mod and they are also significantly heavier.

I'm interested that you have some form of nut on side reinforcing strips where the fixing goes through. On both my cars, there was a hole cut in this strip so that the bolt fitted directly on the bonnet bobbins. The bobbins in the body of my car had failed with original bonnet, not the replacement shown in the photograph, I think they had just worn and corroded away.

I like the idea of the spring loaded pivot and did consider this (IIRC john.p.clegg pioneered it many years ago) but in the end, I went for originality - can't think why on a Zetec car!!

The idea of reshaping the bonnet curvature is also interesting. My original bonnet was quite lightweight and may have sagged, the aftermarket bonnet that I will probably use has better curvature and doesn't need any modification here.