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MG TD TF 1500 Gear shift rattle - Ignition timing BBS discussion at MG-Cars.net
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MG TD TF 1500 - Gear shift rattle - Ignition timing
| Having realigned the Distributor on my TF and about to fine tune the timing, I would appreciate confirmation that gear shift rattle can be caused if the ignition being too advanced - not retarded as stated in some past threads. Thanks John. |
| John James |
| Yes, I can confirm. I had the same problem with the ignition too advances, I lost also some bits ans screws. I saw no advange of running 5° BTC, I prefer the timing at TDC. However, it must be taken into account that my CR is 9:1. Anyway, this is also that your gearbox extension and gear shift need an overhaul. Brown & Gammons did a good job for me. |
| JM Thély |
| John, The gear shift rattle is probably caused by a broken "Anti Rattle Spring" located at the base of the shifter. The only connection between the rattle and timing would probably be the fact that advancing the timing and making the engine run a bit rough could cause a vibration which could therefor make the shifter rattle.. the spring is part # 129 on page 17 of the Abingdon Spares web site or catalog SPW |
| Steve Wincze |
| Thanks everybody. All the anti-rattle devices are present and in good condition. Before realigning the distributor the lever used to chatter momentarily around 3000 rpm, especially in third. When I set the timing initially at 5 degrees BTDC the rattle was more pronounced in 3rd and 4th. I have now retarded the ignition a smidgeon and the rattle is as before. I will fine tune it further compromising between noise and performance. John TF5924 |
| John James |
| I had the same problem on my 51 TD. set the timing at TDC and the problem went away except for the normal rattles of a TD. |
| Tom |
| John. Another thing that I have found to cause rattles such as yours is the valve adjustment.Just reset the valves and it , along with timing change should solve your problem, Sandy Sanders |
| conrad sanders |
| Well, I have said it before and I'll say it again. I find it quite bizarre to detune an engine to get rid of a rattle. Does anyone wonder why the designers didn't do this rather than fit the extension with the antirattle devices? That way they could have saved even more money in the construction of these cars. Has it occured to anyone comtemplating these strange "cures" that the fault may just lie not only in worn bushes in which the gear lever extension slides, weak anitrattle springs, sloppy fitting gear levers etc., etc., but also in the overall balance of the engine and gearbox components? My engine was carefully balanced before and during rebuilding, and all the worn components in the gearbox replaced. The aluminium extension was bushed to remove the wear in the sliding shaft. The engine is supercharged, the timing is set to about 7 degrees BTDC and the valves adjusted to give the best performance compatible with least tappet noise that I can find. The gear lever extension does not rattle at any rpm range. Taken to the limits of illogicality, I suppose some owners, desperate to find a cure for this irritation, may resort to screwing down the valves until they burn out, retarding the ignition to the point that the engine barely runs, substituting the rubber engine mounts ( or perhaps doubling up) for solid metal ones, all in an attempt to eliminate the vibration of the engine at certain revs, which is reflected in the irritating buzzing noise in the gearlever. By the time they reach this point, the car won't run at all, but at least they will be able to sit in the cockpit, in total vibrationless silence, dreaming of the days when they happily drove their toy, with their right (or left, depending) knee jammed against the offending object Don't amputate your leg to cure an ingrowing toenail. |
| G.E. Love |
| Hello MGistes, I had the same problem with my TD Gearbox and to avoid rattle I have modified the gear box with a system developed in Australia which consist in modifying the selectror lever (rear)with a piece of nylon or similar with a special attachement. The system looks like the MGB system. If you are interested you can contact mky Australian friend Bob Bazzica: mgsales@mgsales.au.com |
| georgibus |
| Or you can just bungee cord it over to the side. Heh Heh. |
| D Clark |
| If you have replaced all the anti-rattle spings etc and it still rattles, just lean your knee against it. Viola, no more noise! |
| Neil Nelson |
| Neil et al, Perhaps "gear shift" rattle is the wrong description. It sounds as if the "chatter" comes from further up the linkage, Anyway, after fitting a pertronix unit, I have statically set the timing at TDC and double checked it with a timing light at 500 rpm (yes, the engine will now idle smoothly at 500). The "rattle" which was present in third/fourth gear around 3000rpm has now gone. John |
| John James |
| There is no question that timing too advanced causes a rattle from the gearshift. I can demonstrate this to anybody, since I have a control to change the spark advance from the dashboard, and if timing is wrong - too advanced - a "nice" geassh*t rattle warns me to retard it. Ideally it should be a few degrees before TDC - depending on fuel, and also on temperature etc. Denis |
| Denis L. Baggi |
| My son is an engineer with Audi R&D who works on ECU design and programing. When I told him about TF gearshift rattle, he said: We can shake an engine to pieces with a rogue advance curve! OK, modern engine are much more powerful, but think of all the years of wear and tear our XPAG's have had to put up with. I think I'll forgive a bit of looseness in the linkages. |
| John James |
| John I would be interested in your son's comment or from the 'you guys' as to timing for max. torque (at around 2700-3700 rpm) and gear lever rattle. If the timing is advanced to the point where max. torque is produced, is this harmful to the engine if the gear lever is making a slight chatter under power? or to put it more simply, is advancing the timing potentially harmful to the engine? This might seem an obvious question - but worth discussion. There was much discussion before Xmas about timing set statically re: TDC, but I usually set the timing by progressively advancing the timing until the motor runs more harshly under full power in third between 2700-3700 rpm. When the point is reached when the gear lever will rattle I have assumed that the point has been reached when the rapid ignition is putting strain on the pistons so then the timing is retared just a little. Same solution without having to use a timing light. From the comments from G E Love, retarding the timing to avoid the rattle, equates to retarded timing, and running our cars permanently retarded. Regards Peter 54TF |
| Peter Falconer |
| Peter Surely if we set the static timing at TDC with original spec advance springs fitted we are not retarding it. The engine will be set up as MG intended it to be. If advancing the ignition to gain more power results in harmful vibrations I would rather put up with the more sedate "performance" and reduce the wear and tear on both the car and my sensitive lugholes! All the best John |
| John James |
| John, Much has changed since these engines were introduced, not the least of which is the fuel. I think that the current wisdom of setting them at 5 degress BTDC only returns them to the equivalent of the 1940's/1950's 0 degree TDC setting and isn't actually advancing them at all. Best, Gene |
| Gene Gillam |
| John Well said! Regards Peter |
| Peter Falconer |
| If you retard until no rattle, it will run pitifully. Gene is on the mark. The zero static timing deal was fine with 65 octane gas, low compression, stock cams, etc. Virtually all cars now have modern profile cams, overbored cyls., shaved head/block surfaces, etc. Unlike newer, high reving, multil-valve, high compression and very lean burning modern cars, I think it would be about impossible to damage these motors with too much advance. Believe it or not, I have found rotating (toward advance) the dist. while idling until the rpm stops increasing (usually get a bit rough also), and then retarding just a bit seems to be about right! I think the rattle is simply a resonance that sets up in the shifter mechanism. You don't suppose the spring at the base of the lever, the damper on top, and the big spring at the base of the lever were an attempt to fix this? |
| George Butz |
| George Your method is the same as the one I was using on my MGB. The only downside was a slight pinking if too advanced. I use 97 octane with Castrol Valvemaster in the TF, which has a standard cam and has undergone one rebore in it's 17000 mile life. After a frosty five mile run this morning I turned the distributor until the idle RPM peaked, then retarded it about a third of the way to it's original TDC setting. The car is more frisky now and G/S chatter only occurs momentarily in third around 3000rpm. No doubt I will continue to fiddle with the set up, but I don't think I can improve it much more. Gene Thanks for the info. John TF5924 |
| John James |
| To Peter Falconer Advancing timing too much is very dangerous. When I had initially built my dashboard control, I decided to try as advanced a spark as I could at about 5,000 rpm. Result: a piston, no.4 I think, burnt! I made it home on three cylinders and a lot of smoke. Now, no matter which modern fuel you have, shaved heads, performant camshafts etc., if you hear some rattle, that means timing is wrong. By retarding it a little, the engine runs smoother and is more powerful, and the engine IS NOT RETARDED as someone wrote, but CORRECTLY SET. About a few degrees before TDC. Believe me, I can show it you! Denis |
| Denis L. Baggi |
| Denis and I have crossed swords over this matter on several occassions previously. I am now pleased to see he agrees with me that the engine should be set a few degrees BTDC. and in no way retarded thereby destroying the best performance possible. He is right when he says that if there is a rattle, ( and I presume he means coming from the engine, such as a pinking noise) then the timing is probably too far advanced. BUT, the reason the gearlever is rattling is because there is something wrong with IT, so, fix the rattle there and leave the timing alone. I used to have a rattling noise coming out of a wheel disc at certain speeds. That was because the medallion was loose. It only occured at certain speeds. To cure it I fixed the medallion's fit in the hub cap. I did not confine myself to driving the car at speeds other than the one at which the thing rattled. I suggest the same thing should be done with the gear lever problem. Fix the thing which is wrong, broken, worn out or whatever, and leave the engine alone. |
| G.E. Love |
| John So after having recommending to me to "stick to the specs" . . . it is my turn to give make some cautionary comment. Setting the timing by advancing the idling speed is fine for the MGB but not for the TF which does not have a vacumn advance. A TF will indeed idle faster if the timing is advanced as the inlet manifold is in vacumn, the oxygen and fuel molecules in the upper cylinder are few and far between, so the extra time for combustion, will result in better combustion and more power. But as soon as the 'foot goes down' the timing will be too advanced. This would not occur with the MGB which has a vacumn advance, to retard the timing under power. If you now car runs better at 3000 rpm is may be that the centrifical advance is not advancing sufficiently or the fact that you tried it out on a frosty winter morning (safe conditions). I realised that TF's need to have the timing more advanced for idling and for gently ambling through the countryside but still retarded under power to avoid pinking, so I fitted a distributor from a Wolseley 4/44 (XPAW) which has a vacumn advance mechanism and of course have kept the original if ever required. I provides a good improvement. I am not familar the the benefits of fitting a Pertronix unit (or a non stock cam). With my current timing settings, I cannot advance any further without causing pinking on 96 octane which occurs only on very hot days. Best Regards that climate conditions will not force you to change your settings. Peter |
| Peter Falconer |
| If I might digress a bit,as a cheap way of fitting electronic ignition to my Austin 1800 {which has a B series 1800 motor}I modified a second hand Nissan Pulsar electronic distribtor to fit, and this improved the Austin's performence greatly. I made some measurements and found that I could do the same to my TD. It would require hooking the vacume advance to the manifold. Has anyone done this, I have no idea if the advance curve of the Pulsar would suit the TD. Dave |
| David Broadbridge |
| Getting back to the matter of fixing the gear lever's rattle, I should have added that it is not usually entirely satisfactory to "just" re-bush the holes through which the extension rod slides and to replace the 3 springs in the extension. I have found it is also important to remove as much slop as possible in the selector rod ends and the extension rod's actuating attachment which engages the selector rod ends. That means replacing or re-facing those components as well. Attention to all these points will remove the cause of the irritation regardless of the engine's state of ignition advancement. |
| G.E. Love |
| Peter I have gone for the compromise set-up to take modern petrol into account. The rattle was never that bad anyway and always short lived. I am assuming the gearbox linkage is in relatively good condition as it has only done 17000 miles The shift feels sharp and positive. So far I have never suffered any pinking or run on in the TF. I can recommend the Pertronix electronic (magnetic) ignition. It is easy to fit and has improved the starting and running of the engine. John |
| John James |
| While I agree with Geoff Love, I would like to add that if timing is properly set - a few degrees before TDC, we both say - nothing should rattle anywhere. Now, this may be typical of my own TD and maybe not representative, but in the case of too much advance, the first to rattle - my warning - is something in the gearsh*t lever. Pinking in the engine comes with further advance. So you may say I have a 2-step alarm! Also, Geoff, when I write and wrote "retarded", I never meant in respect to what it should be, only in respect to the "too much" one may have set it. In this sense, we may be both "retarded" compared to Einstein, but that does not make us that dumb! Maybe we function just fine! Lastly, while I have no quantitative data to support this, I know from experience that resetting, read advancing, timing at high speed on a highway does give some more power, provided one resets it afterwards. Hence I think that finding the "perfect" timing for al situations is a myth, or at least an art I do not qualify for, except minute by minute! Denis |
| Denis L. Baggi |
| After initially setting the timing in the approximately "right" position, I have always adjusted my ignition timing by experience in actual driving and performance conditions. I advance it to the point that it starts to pink, then back it off a small amount, especially under heavy accelerating conditions. On my car that seems to equate to app. 7 degrees B.T.D.C. static, using the highest grade petrol I can find. It seems to run well both in traffic and on the open road. Of course, I may be a bit retarded to do it that way! But I have to say that Denis has an advantage by using a driver controlled advance/retard mechanism. That's the best of both worlds. |
| G.E. Love |
| I got an overhauled distributor. So new timing was necessary. I must admit, that in my car there is a dependence between timing and some kind of rattle noise. |
| W_Mueller |
| Does anyone get this rattle with a newer 5 speed in the car? The original transmissions in our cars being 60+ years old have held up quite well as far as I'm concerned, but, they are quite old and at times I think we expect a little to much from them. A little noise from the old girl isn't all that bad. Age has a way of doing that. I remember when I could vault over a 6' fence with no problem, now I have a hard time just stepping over a 3' fence! Grin. PJ |
| PJ Jennings |
| Very interesting discussion perhaps some of you could clarify a couple of things.
I find it interesting that the rattle mentioned happens around 3000 rpm. I thought that was around where max advance occurred near that point. Is that just a coincidence? Or are some of us experiencing this rattle as we transition thru that point of max advance. If we retard the timing to compensate for the rattle and eliminate the rattle do we lose that max advance and consequently sacrifice top end performance. I agree engine tune, quality of parts, gasoline octane and quality of the distributor have a impact. In my case I run 8.3 to 8.6 compression, 6 pounds of boost with a modern supercharger, larger valves, ported and polished head and rebuilt standard rockers. Bottom end is stock as of 900 miles ago. When I had my distributor rebuilt for that configuration, Advance told me to set initial advance at 12 to 15 degrees BTC. I show complete advance of 30 degrees around 3000 rpm. Tranny was gone thru at the same time as engine rebuild. Joe |
| JWP Policastro |
| Remember this thread : http://www2.mg-cars.org.uk/cgi-bin/or17?runprog=mgbbs&access=&mode=archiveth&subject=8&subjectar=8&thread=2017100510150732122 I have now good results about this topic. Need to be confirmed but if so, I will publish in a few month. Laurent. |
| LC Laurent31 |
| PJ the only thing I can say about my stock transmission is that as I advanced the timing (small incriments at a time while stopping and driving) the rattle got worse as I advanced the timing and less as I retarded it. Tim |
| Timothy Burchfield |
| Excessive Gear shift rattle is caused by inaudible detonation,caused by too much ignition advance. This is why head gaskets leak (compression) between cylinders, and the top piston rings break. I agree on 5 degrees BTDC with the highest octane fuel, as long as the distributor advance plate gives 15 degrees advance = 30 crankshaft degrees = 35 total. The later TF distributor advance plate is 12 degrees = 24 crankshaft degrees....
When distributors are recurved, historically they give 36 degrees total (12=24 + 12) 12 static timing. Len Fanelli Abingdon Performance LTD. |
| Len Fanelli |
| Len, 35 total degrees at what RPM? Tim |
| Timothy Burchfield |
Tim, @ 3000 RPM for a recurved distributor. but up to about 5000 RPM for SOME stock distributors.
 |
| Len Fanelli |
This thread was discussed between 08/01/2004 and 26/07/2018
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