TVR ‘S’ Series “Wide Open Bonnet” Solutions
Discussion
Over the past few years ingenious ‘S’ owners have come up with a variety of solutions to the problem of limited access caused by the restricted opening range of the bonnet. This being a classic example of TVR “value engineering” ie lash up the cheapest bodge possible and let the owner do the R&D 
Here are a few well documented solutions:-
https://www.pistonheads.com/gassing/topic.asp?h=0&...
https://www.pistonheads.com/gassing/topic.asp?h=0&...
https://www.pistonheads.com/gassing/topic.asp?h=0&...
If there are others that I’ve missed please add to the list.
Phillpot developed a very elegant solution but apart from this ”teaser” I can’t seem to find a full explanation at the moment.
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Here are a few well documented solutions:-
https://www.pistonheads.com/gassing/topic.asp?h=0&...
https://www.pistonheads.com/gassing/topic.asp?h=0&...
https://www.pistonheads.com/gassing/topic.asp?h=0&...
If there are others that I’ve missed please add to the list.
Phillpot developed a very elegant solution but apart from this ”teaser” I can’t seem to find a full explanation at the moment.
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Good man Joe, it was worth bringing the info together to help other people.
I did see another well engineered at SCH 2021, must see if I have any photos.
One issue for anyone considering a wide open bonnet mod. Once you have done it you will NOT go back! So in my opinion there is no point in keeping 'originality'. There seems to me to be no point in assuming your new wide open bonnet mod has to fit into the original square tubes at the end of the cross member, These are quite thin, especially on early cars, and often damaged anyway and the idea of replacing those short bits of tube first seems daft.
Using the original tubes simply constrains your design options. Think outside that particular piece of box!!
I did see another well engineered at SCH 2021, must see if I have any photos.
One issue for anyone considering a wide open bonnet mod. Once you have done it you will NOT go back! So in my opinion there is no point in keeping 'originality'. There seems to me to be no point in assuming your new wide open bonnet mod has to fit into the original square tubes at the end of the cross member, These are quite thin, especially on early cars, and often damaged anyway and the idea of replacing those short bits of tube first seems daft.
Using the original tubes simply constrains your design options. Think outside that particular piece of box!!
Me too.
2 runways made from scaffold plank and 4x2.
The 4x2 blocks at the end allow the bonnet to open to a full 90degrees: movement is safely stopped by the valance hitting the tyres.
The runways allow room for the electric/hydraulic scissor lift which lives under the car. I use it all the time, for example for working in the cockpit without having to kneel down.
And it's easier to get in and out, especially for this septuagenarian with dodgy knees.
2 runways made from scaffold plank and 4x2.
The 4x2 blocks at the end allow the bonnet to open to a full 90degrees: movement is safely stopped by the valance hitting the tyres.
The runways allow room for the electric/hydraulic scissor lift which lives under the car. I use it all the time, for example for working in the cockpit without having to kneel down.
And it's easier to get in and out, especially for this septuagenarian with dodgy knees.
So being as somebody else raised the subject which is the best wide open mod, I dont want to open the can of worms but I always end up going in circles on the various designs then I cant find them again, other problem is no-one manufacturing and Ive not got a fab man on hand. Is there one thats manufactured or can be?
abercoms said:
......... Is there one that's manufactured or can be?
If you mean "is there and off-the-shelf" solution" then the answer is "no". At least I don't think so. However that's not to say some enterprising individual couldn't make up a small batch. The difficulty is that all TVR's are different and a hinge assembly which was made for one might not necessarily fit another. In the meantime, I'm afraid you'll have to DIY.
Edited by v8s4me on Friday 3rd February 08:49
abercoms said:
problem is no-one manufacturing and Ive not got a fab man on hand.
If you ask any local garage I'm sure you will find a fabricator near you willing to take this on if you give them the design. The metalwork involved is relatively straightforward, the cleverness is in the geometry.If you are designing or making one yourself the main design issue is where the PIVOT should be moved to in order to get the maximum opening without the bonnet touching the ground or needing to be cut.
Bob Honnor and I studied this. Bob used CAD, I used an old fashioned drawing board!
We posted our dimensions.
One issue few people seem to have addressed is that ideally, from an engineering stress point of view, the pivot should be directly in line with the plywood web. If it is not in line there is a bending force on the ply and we know the ply can become a weak point.
If you stick to mounting your new hinges onto the old uprights it is very difficult to get the pivot in line with the ply webbing.
One further thing I would add. Make sure there is a strong physical overtravel stop to the bonnet hinge mechanism. That is a big bonnet, 'throw' it open without a stop and you really do risk damage to the metalwork, the ply or the ply to glassfibre junction. Remember you may also have to open the bonnet on a windy day! Don't risk that bonnet.
Bob Honnor and I studied this. Bob used CAD, I used an old fashioned drawing board!
We posted our dimensions.
One issue few people seem to have addressed is that ideally, from an engineering stress point of view, the pivot should be directly in line with the plywood web. If it is not in line there is a bending force on the ply and we know the ply can become a weak point.
If you stick to mounting your new hinges onto the old uprights it is very difficult to get the pivot in line with the ply webbing.
One further thing I would add. Make sure there is a strong physical overtravel stop to the bonnet hinge mechanism. That is a big bonnet, 'throw' it open without a stop and you really do risk damage to the metalwork, the ply or the ply to glassfibre junction. Remember you may also have to open the bonnet on a windy day! Don't risk that bonnet.
The other issue to watch out for is the bottom valance fouling the chassis when the bonnet is opened. Most solutions required a bit of the valance to be cut away be aware of that. The V8S bonnet has a deeper valance than the V6 so this is a particular issue on that car and the reason I never got around to this job. I never managed to find the time to adapt one one of the solutions to work on the V8S without cutting into the valance.
Absolutely. I am currently working on another S which is original, who on earth came up with that absolute abortion of a method to hold the bonnet. About the only advantage is that if the bump the car it crumples (collapses!) very easily.
This S has hinges in a very similar condition to the ones on my S when I got it; the box sections are bent, one bolt has moved, the threaded bar is rusted and has drooped, and the plates to the ply have distorted under the bending moment. It must have taken quite an effort to get the design so wrong!
This S has hinges in a very similar condition to the ones on my S when I got it; the box sections are bent, one bolt has moved, the threaded bar is rusted and has drooped, and the plates to the ply have distorted under the bending moment. It must have taken quite an effort to get the design so wrong!
My design for the V8S bonnet was done specifically to avoid having to cut away the valance on the bonnet. It also uses the original chassis mounting points, so you don't need to cut off any of the chassis.
Every man to his own in terms of how much of the original car you are prepared to cut off to achieve an end result. I just wanted to have the ability to switch the car back to 'as factory' if a subsequent buyer wanted to do so.
Bonnet overtravel is taken care of by a couple of gas struts, an idea that was shamelessly stolen from Phillpot. They also help to open the bonnet once you have moved the pivot point so far forwards and down.
Michael, of Taimar ownership, 3D printed me up a couple of 'stay clips' that go over the open rod of the gas struts to stop the bonnet blowing closed in any form of breeze. Don't know if they are really necessary, but better to be safe than sorry I thought.
I have thought about getting a batch made in some sort of group buy, but it would need a few more people to make their own sets up to trial out my alternative designs for the S1/2 (no driving light) and the S3/4 (driving light) bonnet variants. Quite a few people have had sets of drawings off me, but no-one has actually made any and gotten back to me yet.
If anyone else wants a free set of the drawings then drop me a PM with your email address, letting me know which bonnet you've got on your car and I will gladly send them out to you.
Every man to his own in terms of how much of the original car you are prepared to cut off to achieve an end result. I just wanted to have the ability to switch the car back to 'as factory' if a subsequent buyer wanted to do so.
Bonnet overtravel is taken care of by a couple of gas struts, an idea that was shamelessly stolen from Phillpot. They also help to open the bonnet once you have moved the pivot point so far forwards and down.
Michael, of Taimar ownership, 3D printed me up a couple of 'stay clips' that go over the open rod of the gas struts to stop the bonnet blowing closed in any form of breeze. Don't know if they are really necessary, but better to be safe than sorry I thought.
I have thought about getting a batch made in some sort of group buy, but it would need a few more people to make their own sets up to trial out my alternative designs for the S1/2 (no driving light) and the S3/4 (driving light) bonnet variants. Quite a few people have had sets of drawings off me, but no-one has actually made any and gotten back to me yet.
If anyone else wants a free set of the drawings then drop me a PM with your email address, letting me know which bonnet you've got on your car and I will gladly send them out to you.
![](https://thumbsnap.com/sc/UyLh5SaH.jpg[/img]</a> <a href="https://thumbsnap.com/p5rWrBDu" Target="_blank" rel="nofollow">[img]https://thumbsnap.com/sc/p5rWrBDu.jpg)
Before and after images.
Before, the nose of the bonnet hit the floor just as you were able to get the bonnet stay in place.
After, there is a clearance of around 25mm under the nose of the bonnet when it's fully open. You can set this and the opening angle depending upon where you fix the top gas strut mountings.
I can now sit on the front wheel and work in the engine bay.
Gassing Station | S Series | Top of Page | What's New | My Stuff