Edmond Posted October 20, 2008 Report Share Posted October 20, 2008 (edited) We had the TR4A up on a lift today...the type with 4 arms which extend under the car to support it at points under the chassis behind the front wheels and ahead of the rears. I happened to open the driver's door and couldn't close it - the rear of the car had "sagged". The chassis however appears sound and we have not detected any cracks even after scraping the underseal away. Is such sagging to be expected on a TR4A chassis? Edited October 20, 2008 by Edmond Quote Link to post Share on other sites
Nick Webster Posted October 21, 2008 Report Share Posted October 21, 2008 There are two nautical terms that are quite useful - Hogging and Sagging. Hogging is what you are describing, where the ends are drooping down from a middle support. Sagging is where the ends are supported and the middle droops. Unfortunately the TR4A is prone to sagging. It does not usually get much of a chance to hog because normally the wheels are on the ground! The first sign of sag requiring attention is when you take off a Surrey top metal roof but then mysteriously the holes do not line up and you cannot get it back on again. When the doors start to misalign then it is getting really bad. The gap at the top can disappear to zero. Obviously the cars did not sag to excess when new so it is a sign that something is weaker than it was. The rear chassis design is poor - the rear "legs" aft of the diff are thinner metal anyway. The chassis cannot take all the blame because with a drooping car you will probably find the B posts, sills and rear deck are corroded to some degree as well.The circumstances you are describing with the car jacked up are a pretty severe test and really you should check the door (or Surrey) fit with the car on the ground. It is rather stating the obvious to say that there's a problem if you still have trouble with the doors, but conversely if the gaps etc. are ok and there's no undue movement in the area of the door catches as you are driving along, then don't worry too much about what you have witnessed with it up in the air. Nick Quote Link to post Share on other sites
Richard Crawley Posted October 21, 2008 Report Share Posted October 21, 2008 It’s not necessarily a doom & gloom scenario, here’s a related thread on TR6 but TR4A chassis is very similar. http://www.tr-register.co.uk/forums/index....showtopic=15982 Quote Link to post Share on other sites
TR 2100 Posted October 21, 2008 Report Share Posted October 21, 2008 (edited) Obviously the cars did not sag to excess when new so it is a sign that something is weaker than it was. I'm not so sure that is obvious, or even true. AlanR Edited October 21, 2008 by TR 2100 Quote Link to post Share on other sites
Nic Bowman Posted October 21, 2008 Report Share Posted October 21, 2008 I'm not so sure that is obvious, or even true. AlanR I agree, I have had two TR4as, my current one is ex US, real tidy chassis no welding, the other a UK car with lots of chassis overplating, both sagged when jacked so the door fit changes. It is always okay when put back on the floor. So, don't panic too much! Nic Quote Link to post Share on other sites
Edmond Posted October 21, 2008 Author Report Share Posted October 21, 2008 (edited) Nick, Alan, Nic, Richard - thanks. I took the morning off work so that we could repeat our little exercise with the lift. We checked the chassis again and all it revealed was few small patches in a couple of places. The only problem was that they were stitch welded rather than seam welded. That will be corrected. On the ground the gaps around the doors are fine: even all round albeit not Lexus tight but the never were. Up on the lift...sagging...sorry hogging! At striker plates/door catch level we are talking 3mm stretch. On the ground things are fine. Nick I hadn't appreciated that the "legs" aft of the diff are thinner metal - you are right. In the absence of finding a crack we are tending to the view that this "feature" is as much a result of the design of the TR4A frame as any fatigue in the metal. Is there any precautionary strengthening which people commonly do to the chassis? The passenger door alignment isn't great either. On closer examination this seems to be a result of a new door skin not fitted entirely well, the appearance of which could be improved to some degree with some packing between the chassis/body mounts at the rear. I promised myself after getting my MGB sills, castle rails, wings etc done earlier this year that I going to avoid (1) the emotional roller coaster of restoring old cars and (2) losing the plot and instead of just enjoying the damn thing obsessing over every flaw in the paint finish. Some chance Edited October 21, 2008 by Edmond Quote Link to post Share on other sites
MikeF Posted October 21, 2008 Report Share Posted October 21, 2008 Nick, Alan, Nic, Richard - thanks. I took the morning off work so that we could repeat our little exercise with the lift. We checked the chassis again and all it revealed was few small patches in a couple of places. The only problem was that they were stitch welded rather than seam welded. That will be corrected. On the ground the gaps around the doors are fine: even all round albeit not Lexus tight but the never were. Up on the lift...sagging...sorry hogging! At striker plates/door catch level we are talking 3mm stretch. On the ground things are fine. Nick I hadn't appreciated that the "legs" aft of the diff are thinner metal - you are right. In the absence of finding a crack we are tending to the view that this "feature" is as much a result of the design of the TR4A frame as any fatigue in the metal. Is there any precautionary strengthening which people commonly do to the chassis? The passenger door alignment isn't great either. On closer examination this seems to be a result of a new door skin not fitted entirely well, the appearance of which could be improved to some degree with some packing between the chassis/body mounts at the rear. I promised myself after getting my MGB sills, castle rails, wings etc done earlier this year that I going to avoid (1) the emotional roller coaster of restoring old cars and (2) losing the plot and instead of just enjoying the damn thing obsessing over every flaw in the paint finish. Some chance FWIW: I never had a chassis car, newish or old or any type where this hogging/sagging as I now know it didn't happen, and have never worried that much about it. Just assumed it happens stationary as when driving its called flex or scuttle shake etc, I just automatically shut the doors before jacking. [Of course I have never owned a really new or expensive car.] Mike Quote Link to post Share on other sites
Nick Webster Posted October 21, 2008 Report Share Posted October 21, 2008 Nick, Alan, Nic, Richard - thanks. I took the morning off work so that we could repeat our little exercise with the lift. We checked the chassis again and all it revealed was few small patches in a couple of places. The only problem was that they were stitch welded rather than seam welded. That will be corrected. On the ground the gaps around the doors are fine: even all round albeit not Lexus tight but the never were. Up on the lift...sagging...sorry hogging! At striker plates/door catch level we are talking 3mm stretch. On the ground things are fine. Nick I hadn't appreciated that the "legs" aft of the diff are thinner metal - you are right. In the absence of finding a crack we are tending to the view that this "feature" is as much a result of the design of the TR4A frame as any fatigue in the metal. Is there any precautionary strengthening which people commonly do to the chassis? The passenger door alignment isn't great either. On closer examination this seems to be a result of a new door skin not fitted entirely well, the appearance of which could be improved to some degree with some packing between the chassis/body mounts at the rear. I promised myself after getting my MGB sills, castle rails, wings etc done earlier this year that I going to avoid (1) the emotional roller coaster of restoring old cars and (2) losing the plot and instead of just enjoying the damn thing obsessing over every flaw in the paint finish. Some chance 3mm? What on earth are you worried about? Come back when it is three inches. Nick Quote Link to post Share on other sites
BrianC Posted October 22, 2008 Report Share Posted October 22, 2008 3mm? What on earth are you worried about? Come back when it is three inches. ... or when the doors fly open on roundabouts Many years ago, when I took my Mum for her first ever 'ton-up' drive in my newly acquired pride and joy, an ancient and well-used (abused?) TR3A, I nearly lost her as we circumnavigated a tiny roundabout and the passenger door flew open due to the flexing. Fortunately, I managed to grab her and keep her aboard, but it certainly made an impression on her. I subsequently learned that this was a fairly common problem, sometimes 'fixed' by using an ordinary domestic sliding door-bolt to lock the door to the inner sill for rapid motoring. The art of coarse TR maintenance was at its peak in those days. Quote Link to post Share on other sites
Edmond Posted October 22, 2008 Author Report Share Posted October 22, 2008 (edited) ... or when the doors fly open on roundabouts Many years ago, when I took my Mum for her first ever 'ton-up' drive in my newly acquired pride and joy, an ancient and well-used (abused?) TR3A, I nearly lost her as we circumnavigated a tiny roundabout and the passenger door flew open due to the flexing. Fortunately, I managed to grab her and keep her aboard, but it certainly made an impression on her. I subsequently learned that this was a fairly common problem, sometimes 'fixed' by using an ordinary domestic sliding door-bolt to lock the door to the inner sill for rapid motoring. The art of coarse TR maintenance was at its peak in those days. Brian - I had the same experience sitting in the front seat of the English Lit/drama teacher's car when I was 12. He had a Triumph Herald Estate and was doing about 20 mph on a roundabout. The door flew open half way around and out I went...luckily he grabbed me with his left hand and the yahoos bouncing around in the back pulled me back in! His comment..."Oh it always does that". Things were different in 1969. Today there would be risk assessment, the possibility of litigation etc etc Edited October 22, 2008 by Edmond Quote Link to post Share on other sites
Huey Posted October 22, 2008 Report Share Posted October 22, 2008 Brian - I had the same experience sitting in the front seat of the English Lit/drama teacher's car when I was 12. He had a Triumph Herald Estate and was doing about 20 mph on a roundabout. The door flew open half way around and out I went...luckily he grabbed me with his left hand and the yahoos bouncing around in the back pulled me back in! His comment..."Oh it always does that". Things were different in 1969. Today there would be risk assessment, the possibility of litigation etc etc During a visit to Manvers Triumph, Clive demostrated this to me on my TR4 - it is quite normal but is a bit disturbing if you have not seen it before. Quote Link to post Share on other sites
Tr4Tony Posted October 22, 2008 Report Share Posted October 22, 2008 Hi Another aspect that no one has mentioned thus far is the way the body mounts perform and how they contribute to hogging / sagging, particularly if they have fallen out. Check these over and if necessary repack the mounting points with bits from a new kit (and check the bolts for stretching also) - the whole thing is only £30 or so but in my experience you can tighten up a very baggy 4a considerably without spending much money at all. Your 3mm might look like a lot but in my experience it sounds entirely typical of a decent IRS car with its original mountings still in there. Regards Tony Quote Link to post Share on other sites
Edmond Posted October 22, 2008 Author Report Share Posted October 22, 2008 Hi Another aspect that no one has mentioned thus far is the way the body mounts perform and how they contribute to hogging / sagging, particularly if they have fallen out. Check these over and if necessary repack the mounting points with bits from a new kit (and check the bolts for stretching also) - the whole thing is only £30 or so but in my experience you can tighten up a very baggy 4a considerably without spending much money at all. Your 3mm might look like a lot but in my experience it sounds entirely typical of a decent IRS car with its original mountings still in there. Regards Tony Tony - you may well be right. I'm just home from a trip to see the TR4A in the workshop and remembered to look very closely at the mounting points. In a nutshell there is scope for improvement - the packing is all but absent from the driver's side rear area and elsewhere it's as if the packing has compressed slightly. Unconnected with this, we noticed that he passenger side rear shock absorber was a little weaker than the driver's side one. Another item for the list. Quote Link to post Share on other sites
Allan Westbury Posted October 23, 2008 Report Share Posted October 23, 2008 I seem to remember there was a queery in TRAction a couple of months ago about this & the recommendation was to weld strengthening pieces across all the angles on the chassis. has anyone done this & did it help? Quote Link to post Share on other sites
Edmond Posted October 24, 2008 Author Report Share Posted October 24, 2008 I seem to remember there was a queery in TRAction a couple of months ago about this & the recommendation was to weld strengthening pieces across all the angles on the chassis.has anyone done this & did it help? Ollie - thanks. I see only two places where any sort of additional strengthening has been done - a couple a pieces let in to right angle corners, tack welded in four places. Would be keen to know if anyone has found improvement by more extensive strengthening. Ed Quote Link to post Share on other sites
bob-menhennett Posted October 24, 2008 Report Share Posted October 24, 2008 Hi Guys I attended a bodywork course ...run by the Register..many years ago and the recommendations are in accord with Roger Wiliams restoration book.Mines's a 4 so I included two very large solid steel bars for the rear out riggers.These went through the tube and far enough inside the main chassis before I welded them up. My TR4 was undrivable before I started my restoration so can't comment on the before or after situation.I took on board the "collective wisdom" of the professionals who had been there before me. Bob Quote Link to post Share on other sites
Richard Crawley Posted October 24, 2008 Report Share Posted October 24, 2008 (edited) I took on board the "collective wisdom" of the professionals who had been there before me. This is the key thing to consider when making any chassis modifications; think carefully before adding strengthening or reinforcing gussets etc. except to recognised weak points & in way that has previously been proven to work. It may seem crazy but making a structure ultra stiff without considering stress points can create more problems than it cures & the process of welding will also create additional stress points. Edited October 24, 2008 by Richard Crawley Quote Link to post Share on other sites
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