Mk2 Chopper Posted June 7, 2020 Report Share Posted June 7, 2020 6 hours ago, Mike C said: If the main catch works the hook is not needed. If the bonnet springs open and you are driving normally the hook is not needed. If you are driving along and the bonnet springs open and then you have to brake suddenly the bonnet will fly fully open and you have to ease off quickly on the brakes or drive along with the bonnet obstructing your view until you can reduce braking. In my case it was quite unnerving because it was sudden and unexpected on a freeway. I'm amazed that the bonnet could lift under heavy braking, I'm not going to test it. I'll take your word for it! Gareth Quote Link to post Share on other sites
rcreweread Posted June 7, 2020 Report Share Posted June 7, 2020 I think I am right in saying that TR4 and early TR4A didn't have the safety hook and I believe it was introduced on later cars to stop the bonnet popping open in a frontal smash and then being driven through the windscreen. Maybe those without a hook have had an earlier one fitted? Cheers Rich Quote Link to post Share on other sites
harlequin Posted June 7, 2020 Report Share Posted June 7, 2020 1 hour ago, Mk2 Chopper said: I'm amazed that the bonnet could lift under heavy braking, I'm not going to test it. I'll take your word for it! Gareth If the catch let's go at speed the bonnet will be lifted to a bit above drivers eye level by the slipstream over the bonnet and windscreen. Not a disaster but still dangerous. George Quote Link to post Share on other sites
ChrisP Posted June 7, 2020 Report Share Posted June 7, 2020 35 minutes ago, rcreweread said: I think I am right in saying that TR4 and early TR4A didn't have the safety hook and I believe it was introduced on later cars to stop the bonnet popping open in a frontal smash and then being driven through the windscreen. Maybe those without a hook have had an earlier one fitted? Cheers Rich Hi Rich I can’t believe the catch would do any good in an accident it’s so flimsy. If that was the purpose of it it’s a terrible design. chris. Quote Link to post Share on other sites
RogerH Posted June 7, 2020 Report Share Posted June 7, 2020 Hi Folks, the hook is pointing the wrong way to stop the bonnet being propelled rearwards into the screen (front end smash) I like the idea of stopping the bonnet lifting too far if it became unhooked. Roger Quote Link to post Share on other sites
John L Posted June 7, 2020 Report Share Posted June 7, 2020 Great you managed to get it open, but I think your emergency unlocking catch is on the wrong side of the main bracket, and fitted with a small headed bolt, also fit a stop bolt as well, not shown in this picture. John Quote Link to post Share on other sites
Mike C Posted June 7, 2020 Report Share Posted June 7, 2020 45 minutes ago, harlequin said: If the catch let's go at speed the bonnet will be lifted to a bit above drivers eye level by the slipstream over the bonnet and windscreen. Not a disaster but still dangerous. George That's what I thought as I drove home to adjust the latch after it sprung open . The unlocked bonnet was wafting up and down in the airstream .Aerodynamic forces were keeping the bonnet down. The bonnet was restrained by the hinges at the front- under hard braking, and as the speed dropped, the braking forces on the bonnet suddenly overcame the aerodynamic forces .The bonnet kept rotating after an upward waft and kept rotating- as the higher it lifted the more moment it's decelerating Cof G exerted on the hinges. I hadn't expected this and I was lucky to have enough room to finish the braking in the emergency lane. Quote Link to post Share on other sites
Casar66 Posted June 7, 2020 Report Share Posted June 7, 2020 hmm - should I go for a latch/hook or not? I am afraid that with changing the whole catch the well known problems with the bonnet pops up. I never had any problems with the bonnet so far, not at high speed on German Autobahn (more than 120mls top speed), not at racing on tracks and not even in a heavily front end crash (ok, it was more a front/left-corner crash). Difficult decision. Quote Link to post Share on other sites
Waldi Posted June 7, 2020 Report Share Posted June 7, 2020 I know of 2 friends who had the bonnet lifting and blocking sight: One in an MGB, it flipped over the windscreen (catch on front, hinges on rear so not comparable with a TR6). The other in an E-type, hinges in front too. The bonnet was damaged as in hit the tarmac while braking, luckily not at high speed. I feel it is better to have the safety catch, but the effectiveness of the original TR6 catch is questionable. Anyone made an improvement to the catch? Cheers, Waldi Quote Link to post Share on other sites
Richard Green 54 Posted June 7, 2020 Report Share Posted June 7, 2020 I still have the safety hook (original) but the safety catch has been removed from the bonnet. No idea why. Having read these latest post I think I might replace it. Had a bonnet fly up on a car once and it was not a pleasant experience. Quote Link to post Share on other sites
Casar66 Posted June 7, 2020 Report Share Posted June 7, 2020 I had the bonnet lifting twice: on my 1602 BMW and 10 years later again BMW, a 316. Catch at the back like the TRs. The bonnets went up around 5 - 10cm, that's all, nothing happened. Quote Link to post Share on other sites
Mike C Posted June 7, 2020 Report Share Posted June 7, 2020 1 minute ago, Casar66 said: I had the bonnet lifting twice: on my 1602 BMW and 10 years later again BMW, a 316. Catch at the back like the TRs. The bonnets went up around 5 - 10cm, that's all, nothing happened. How hard were you braking? It's easy to see on a TR. Find a clear stretch of road, undo the bonnet catch and the hook , take it up to 100kmh or so and brake hard. Quote Link to post Share on other sites
Casar66 Posted June 7, 2020 Report Share Posted June 7, 2020 you are right, of course. With the right settings you can provoke it. An important issue for me will be if the latch has any safety feature in case of a crash. If so, I will go for it. If its "just" the risk of lifting I will stay with the current state. Quote Link to post Share on other sites
harlequin Posted June 7, 2020 Report Share Posted June 7, 2020 (edited) On the BMWs that I have had (5 series) the bonnet was front hinged but when lowered the front stuck up and you had to push the front down and back to lock it, this engaged an anti lift mechanism by the bulkhead and the lock at the front a cleaver design and as you say Casar66 if the lock let's go the bonnet will only rise a small amount When my TR4 bonnet came undone it was quite scary as it left me blind untill I got the speed down George Edited June 7, 2020 by harlequin Quote Link to post Share on other sites
Scotland Director Posted June 7, 2020 Author Report Share Posted June 7, 2020 11 hours ago, Mike C said: If the main catch works the hook is not needed. If the bonnet springs open and you are driving normally the hook is not needed. If you are driving along and the bonnet springs open and then you have to brake suddenly the bonnet will fly fully open and you have to ease off quickly on the brakes or drive along with the bonnet obstructing your view until you can reduce braking. In my case it was quite unnerving because it was sudden and unexpected on a freeway. Ouch, that’s somewhat unnerving ! I’m going to write an article “should it go or should it stay” because when this happened I initially wanted to get rid of the car ! Quote Link to post Share on other sites
Scotland Director Posted June 7, 2020 Author Report Share Posted June 7, 2020 1 hour ago, harlequin said: On the BMWs that I have had (5 series) the bonnet was front hinged but when lowered the front stuck up and you had to push the front down and back to lock it, this engaged an anti lift mechanism by the bulkhead and the lock at the front a cleaver design and as you say Casar66 if the lock let's go the bonnet will only rise a small amount George That’s the German’s for you ! Quote Link to post Share on other sites
Scotland Director Posted June 7, 2020 Author Report Share Posted June 7, 2020 1 hour ago, Casar66 said: you are right, of course. With the right settings you can provoke it. An important issue for me will be if the latch has any safety feature in case of a crash. If so, I will go for it. If its "just" the risk of lifting I will stay with the current state. That is a great question, not sure that I can answer it ! Quote Link to post Share on other sites
stuart Posted June 7, 2020 Report Share Posted June 7, 2020 FWIW the new repro catches have been strengthened in the area where the hook mounts to the spring plate, the hook on the receiving catch on the bulkhead may need bending forward a little so they all line up and engage as designed, The hook was introduced at the end of TR4 production for US safety laws and judging by some pictures posted on here a few years ago they do actually prevent the bonnet from springing up and going through the screen on a frontal impact. Up to you but I would always fit one. Stuart Quote Link to post Share on other sites
Casar66 Posted June 7, 2020 Report Share Posted June 7, 2020 Many thanks, I will get one. Quote Link to post Share on other sites
Casar66 Posted June 7, 2020 Report Share Posted June 7, 2020 (edited) GWith or without a lash? Edited June 7, 2020 by Casar66 Quote Link to post Share on other sites
Scotland Director Posted June 7, 2020 Author Report Share Posted June 7, 2020 5 hours ago, ntc said: Yikes, ouch ! Thanks for sharing, I suppose decapitation would be a risk without the safety catch ? Quote Link to post Share on other sites
Scotland Director Posted June 7, 2020 Author Report Share Posted June 7, 2020 13 hours ago, John L said: Great you managed to get it open, but I think your emergency unlocking catch is on the wrong side of the main bracket, and fitted with a small headed bolt, also fit a stop bolt as well, not shown in this picture. John I actually got my latch from TRGB and I initially thought that it would be on the outside, but is was “bent” the opposite way. I’m checking with TRGB as I’m not sure now. Quote Link to post Share on other sites
Harbottle Posted June 8, 2020 Report Share Posted June 8, 2020 10 hours ago, Scotland Director said: I actually got my latch from TRGB and I initially thought that it would be on the outside, but is was “bent” the opposite way. I’m checking with TRGB as I’m not sure now. This picture is exactly as mine is fitted, not had any problems in 12 years. I use it as the main bonnet release as it is underneath the dash on drivers side. Paul Quote Link to post Share on other sites
Mike C Posted June 8, 2020 Report Share Posted June 8, 2020 I made one of these years ago. The 1/2' dia. hole latch lever and a tight pivot bolt stops it going overcenter. I can't remember where I found the web pages with this idea. EmergencyHoodRelease (1).doc Quote Link to post Share on other sites
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