foster461 Posted March 1, 2007 Report Share Posted March 1, 2007 So about 15 years ago I replaced a knackered exhaust system with a stainless one. It is still as good as new and I had to remove it while I was fixing some other frame and diff mount issues this winter. I was putting things back together tonight and it struck me that there was no support for the exhaust until the T shaped bracket at the rear, just ahead of the silencer. A quick check of Bentley shows there should be another support somewhere in the vicinity of the gearbox that attaches to two tabs on the two front intermediate pipes. I have no such tabs and I dont see where a bracket would attach to the frame.. This is a US 1974.5 model, should I have a support at this location and if so what does it attach to on the floor/frame as I dont see any evidence of where anything may have been in the past. Stan Quote Link to post Share on other sites
ushes Posted March 1, 2007 Report Share Posted March 1, 2007 Hi, I cant be sure about the US cars but those with 'A' type overdrive have a central bracket that comes down from the gearbox mounting. Both exhaust pipes should have a small bracket welded on with a hole in. It's very fiddly but both holes line up together with the hole in the gearbox bracket then it's bolted together. I'm unsure how the 'J' type cars mount, my car has a non-standard exhaust. Regards Steve Quote Link to post Share on other sites
TIMS Posted March 1, 2007 Report Share Posted March 1, 2007 Stan I'm sure there was a previous comment on this, either from Jonlar or Richard Crawley, which advised against trying to connect this bracket. All to do with counter movement which could rip the bracket from the exhaust and cause rather expensive and fiddly welding requirements. When TRbitz refited my engine they left the bolt out and when asked gave the same reply. I have wedged a rubber packing between the bracket on the exhaust and the rear gearbox mounting and all seems well, with no rattles. I will be interested in the thoughts of others. Regards Tim Quote Link to post Share on other sites
Richard Crawley Posted March 1, 2007 Report Share Posted March 1, 2007 My car is a 71 A type & has these central fixings but a word of caution; I fitted a new SS, 2 pipe system & duly replaced said fittings. About a year later, I noticed a slight fluffing of the exhaust but though it was just a loose bracket. On checking under the car, I found the weld around the outside of the longer dog leg bracket had fractured & pulled away completely. I had to completely remove the system from the car (not a nice job) but was able to repair it by re-welding the bracket back into position. The exhaust is rigidly fixed to the manifold & this central bracket is also rigid & I concluded the reason it had failed was due to vibration stressing around the weld. Mild steel is more ductile than SS & I assume this is why I never had any problems with the several standard systems I’ve had on the car; the brackets were also spot on for location & were tightened before any of the clamps so no strain was put on them. I decided to omit the centre fixings for fear of a repeat fracture occurring; the system is still adequately supported by the rear flexi mounts & doesn’t foul on the Tee shirt tunnel; the MOT bloke didn’t question the missing bolts either. I’m also unsure what the J type fixing arrangement is in the centre (if any) but I wouldn’t worry about it & would advise leaving this fixing off if you have a SS system fitted. Quote Link to post Share on other sites
Richard Crawley Posted March 1, 2007 Report Share Posted March 1, 2007 Stan I'm sure there was a previous comment on this, either from Jonlar or Richard Crawley, which advised against trying to connect this bracket. All to do with counter movement which could rip the bracket from the exhaust and cause rather expensive and fiddly welding requirements. When TRbitz refited my engine they left the bolt out and when asked gave the same reply. I have wedged a rubber packing between the bracket on the exhaust and the rear gearbox mounting and all seems well, with no rattles. I will be interested in the thoughts of others. Regards Tim Must have been me then! Sorry Tim, I didn't spot your response before posting; preview doesn't show any new posts made while your writing yours & I also had breakfast in between! Quote Link to post Share on other sites
foster461 Posted March 1, 2007 Author Report Share Posted March 1, 2007 My car is a 71 A type & has these central fixings but a word of caution; I fitted a new SS, 2 pipe system & duly replaced said fittings. About a year later, I noticed a slight fluffing of the exhaust but though it was just a loose bracket. On checking under the car, I found the weld around the outside of the longer dog leg bracket had fractured & pulled away completely. I had to completely remove the system from the car (not a nice job) but was able to repair it by re-welding the bracket back into position. The exhaust is rigidly fixed to the manifold & this central bracket is also rigid & I concluded the reason it had failed was due to vibration stressing around the weld. Mild steel is more ductile than SS & I assume this is why I never had any problems with the several standard systems I've had on the car; the brackets were also spot on for location & were tightened before any of the clamps so no strain was put on them. I decided to omit the centre fixings for fear of a repeat fracture occurring; the system is still adequately supported by the rear flexi mounts & doesn't foul on the Tee shirt tunnel; the MOT bloke didn't question the missing bolts either. I'm also unsure what the J type fixing arrangement is in the centre (if any) but I wouldn't worry about it & would advise leaving this fixing off if you have a SS system fitted. I'm glad I asked.. The reason I was studying this is that with the rear pipes removed and the diff out I have a clear view through the T-shirt to the ends of the front pipes and they are currently sitting slightly partially eclipsed by the lower plate so this is probably the cause of the occasional clunk when I go over a bump. If I dont have a bracket to help lift/support the system at this point it looks like I need to loosen the front pipes and rotate them so that the ends are level and clear the lower plate so the rear pipes can pass though the tunnel and have enough clearance to not hit the upper or lower plates. Link to picture below.. http://i38.photobucket.com/albums/e119/fos.../frontpipes.jpg Stan Quote Link to post Share on other sites
Tom Fremont Posted March 1, 2007 Report Share Posted March 1, 2007 To each his own, of course, but I've never had a problem with the gearbox anchors. Both the single and dual versions employ brackets having a captive nut which receives the RH bolt for the rear mount. Mine didn't suffer the fracture Richard refers to when using a dual stainless system though the welded tabs on the pipes would seem vulnerable. The single pipe system uses a separate C-clip of heavy gauge sheet steel, so is immune. I prefer to employ these on mine and have adapted the single-type arm with a larger C-clip for use on the large single-bore sport system. The rationale is to isolate engine rock effects to the rear of the gearbox rather than impose them on the exhaust manifold and gasket joint. Installed properly this feature will eliminate contact between the frame and the exhaust pipe(s) too. Quote Link to post Share on other sites
jean Posted March 1, 2007 Report Share Posted March 1, 2007 Strange, I had several types of exhaust and several types of o/d, but never had a problem with the central bracket. On my car it's mounted above the silent block supporting the gearbox and follows the movement of the engine/gearbox, that's the original setup. I'm afraid if you dispose of the bracket, your pipes will be suspended from front to rear on the manifold only and this is rather frightening Vibrations from the engine will be amplified untill they reach the rear brackets. It's like giving an upwards pull to a rope. What's even worse is the effect from rough road surfaces and speed bumps Quote Link to post Share on other sites
Richard Crawley Posted March 2, 2007 Report Share Posted March 2, 2007 I'm afraid if you dispose of the bracket, your pipes will be suspended from front to rear on the manifold only and this is rather frightening Vibrations from the engine will be amplified untill they reach the rear brackets. It's like giving an upwards pull to a rope. What's even worse is the effect from rough road surfaces and speed bumps On the standard system, there should also be a coat hanger type bracket on a flexible strap where the 2 pipes are clamped to the rear box as well as another flexible strap on the rear tailpipe. These take the weight of the rear box & so the pipes are suspended between the manifold (rigid) & the front flexible mount & not all the way back to the rear, which would give problems. Look under any modern car & you will see the exhaust rigidly fixed at the manifold & suspended on 2 or 3 hooks by what are effectively large rubber bands, thus allowing the whole system to move with the engine. My new system SS lasted a year before fracturing at the centre bracket & I concluded it was movement & vibration between the engine mounts & the rigid centre support that caused the stress fracture on the bracket; the exhaust system has now been fitted a further 2 years without any problems or rattles. Tim’s post indicates that TR Bitz also appear to have come to the same conclusion, something I was unaware of! Quote Link to post Share on other sites
jean Posted March 2, 2007 Report Share Posted March 2, 2007 Richard, when I mention back to the rear I understand from the manifold to a position behind the diff, what I consider more or less the rear of the car. Unfortunately there is no provision made on most after market and twin systems to use this bracket. On twin pipes/silencers the rear brackets are behind the pots and that's a long way from the manifold Quote Link to post Share on other sites
Tom Fremont Posted March 2, 2007 Report Share Posted March 2, 2007 My new system SS lasted a year before fracturing at the centre bracket & I concluded it was movement & vibration between the engine mounts & the rigid centre support that caused the stress fracture on the bracket The gearbox and engine moving in unison would theoretically disallow relative movement between the manifold and the rear bracket, excepting that amount due to thermal cycles ( could this in fact be the culprit? ). Like Jean says, I am uncomfortable with subjecting the manifold to the customary movements of the engine relative to the exhaust system. As for modern cars, many of these have flexible exhaust headers ( often stainless, and very expensive! ) which address the phenomenon, and which ultimately give out due to fatigue. The TR approach shifts the fatigue rear of the gearbox, it seems to me Quote Link to post Share on other sites
Tom Fremont Posted March 2, 2007 Report Share Posted March 2, 2007 Unfortunately there is no provision made on most after market and twin systems to use this bracket. As I mention in post #7, the single pipe hanger ( TR250 thru '71 TR6 carb ) is quite suitable for the large single-bore system, requiring only a circumferential strap to fasten onto. Quote Link to post Share on other sites
jean Posted March 2, 2007 Report Share Posted March 2, 2007 (edited) Yes Tom, very correct, that's what I did with the single bore on my 6, adding an additional clip. As the central bracket is fitted on a rubber silent block some thermal stretching might be allowed Edited March 2, 2007 by jean Quote Link to post Share on other sites
TIMS Posted March 2, 2007 Report Share Posted March 2, 2007 Guys If I read all of the thread correctly, the feeling from Tom & Jean is that some form of mounting under the rear gearbox mounting would be a good idea. Yup that makes sense. The problem is that with the bracketry on a two pipe system the mounting is a rigid bolt not any form of flexible support. So in the absence of space for a rubber bobbin mount or a rubber tie, I think I will stay with the rubber packing (about 1/2" thick). Unless I can be persuaded otherwise!! Regards Tim Quote Link to post Share on other sites
Tom Fremont Posted March 2, 2007 Report Share Posted March 2, 2007 Yes Tom, very correct, that's what I did with the single bore on my 6, adding an additional clip. As the central bracket is fitted on a rubber silent block some thermal stretching might be allowed Great minds think alike, right Jean? On mine there's no rubber between the gearbox casting and the hanger bracket, so no compliance there. Quote Link to post Share on other sites
foster461 Posted March 6, 2007 Author Report Share Posted March 6, 2007 It seems that Triumph dropped the center support after 1973, at least in the US.. If you look at the Moss web site, Up through 1971 there was the single pipe http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=32986 In 1972 we switched to the double pipes and added the center support http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=32987 From 73 onwards we have the double pipes but the center support has gone http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=32837 I looked at the system again and there is not much wiggle room. If I lift the pipes enough to clear the lower plate of the T-shirt I’m now close to hitting the bottom of the rear gearbox mount so it is hard to see how to set this up so it doesn’t bang on something at some time. Quote Link to post Share on other sites
Tom Fremont Posted March 6, 2007 Report Share Posted March 6, 2007 Stan, Interesting that Triumph discontinued the intermediate hanger on the latest cars - I would agree it isn't really necessary. So it amounts to a lifestyle choice - if you want one on your car, I suggest bending your own strap around the twin pipes, bring the ends together and drill through, then attach to the factory type hanger. This arrangement won't break anything and will ensure no unwanted banging of the pipes on the frame. Decades ago my father-in-law made a silicone rubber donut for my '250 pipe, which I stuffed in where the pipe passes through the T-shirts. This high-temp rubber was effective in preventing the unwanted contact between the pipe and the frame, and lasted until I discovered the original rig ( which had been removed prior to my acquisition of the car ). I think Triumph's designers got it right with the intermediate hanger. My system has (4) pieces and (5) connections by the time it reaches the intermediate mount and I'm glad they're held harmless from the engine rock effects Quote Link to post Share on other sites
jean Posted March 6, 2007 Report Share Posted March 6, 2007 Looking at the Moss drawings I have the impression the the numbers in the 60th represent the intermediate brackets fixed the the rear casing of the J type o/d just in front of the angle drive. That's the place where I had suspended the pipes when I had a J type o/d mounted on my 6 Quote Link to post Share on other sites
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