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| Idler Gear knock/Rattle https://ausmini.com/forums/viewtopic.php?f=2&t=99651 |
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| Author: | MINI66 [ Mon Feb 03, 2020 11:54 am ] |
| Post subject: | Idler Gear knock/Rattle |
hey guys I purchased a newly built 1275 from a deceased estate ex BMC factory worker and have just installed it in my 1968 CS replica build. I have only put about 5 ltrs of fuel through it so far, it is in a project build so not registered yet and I am trying to avoid idling the new engine prior to run in. I have taken it through 1st and 2nd quickly up the road a few times to load it up a bit for break in and test the box but that is about it apart from revving it a bit unloaded to check AFR . Anyway, it seems to have a idler gear rattle. Didn't seem to have it at first (i think) but now has developed one. Goes away with clutch in. I am running a 45 weber and it has a lightened flywheel but the cam seems fairly tame (No specs). I have 10w40 castrol in it for the time being until run in. If I increase the idle to about 1100rpm the knock pretty much goes away but at 900-1000 it is noticeable. I think that it may be an engine out job and at least check with plastigauge (don't want to have to take the box off as there are no leaks). Do you guys think that I am being too paranoid? Possibly just keep the idle at 1100 and move to valv 20w50 as intended?? (pleeeeease be nice and agree with this!) cheers Rick |
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| Author: | crumpet [ Mon Feb 03, 2020 2:15 pm ] |
| Post subject: | Re: Idler Gear knock/Rattle |
Hi Rick, I am definitely no mechanic mate, and it may be worth checking with others on the forum who know more than me, before you start tearing the gearbox apart. My gearbox has a loud rattling noise from the drop gears and gear sets in the straight cut gearbox which is quite normal, might just pay to check what you have first. Hope this helps mate, Cheers, Chris |
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| Author: | MINI66 [ Mon Feb 03, 2020 2:36 pm ] |
| Post subject: | Re: Idler Gear knock/Rattle |
Thanks Chris Pretty sure that mine are not straight cut as there is just the normal mini box noise when driving. I would be stoked if i was wrong though as there were a few sc boxes that sold in the estate. cheers Rick |
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| Author: | crumpet [ Mon Feb 03, 2020 3:24 pm ] |
| Post subject: | Re: Idler Gear knock/Rattle |
Rick, As you rightly observe SCCR gear sets make a loud whine, and your car may not have a SC gear set However the SC drop gears noticeably rattle and sound terrible at idle, but stop when the clutch is depressed. Not saying this with any expertise only just from what I have experienced, Chris |
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| Author: | MINI66 [ Mon Feb 03, 2020 3:36 pm ] |
| Post subject: | Re: Idler Gear knock/Rattle |
Ok, thanks mate. Probably wouldn't worry about it but my other mini (supercharged 1275) is nice a quiet at 900 rpm idle. |
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| Author: | gtogreen1969 [ Mon Feb 03, 2020 5:00 pm ] |
| Post subject: | Re: Idler Gear knock/Rattle |
In one of my old cars i noticed that different 20w50 oils would increase and decrease the drop gear rattle as well as low oil pressure. I would try a good 20W50 oil mad3 for older cars and see how it goes. |
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| Author: | MINI66 [ Mon Feb 03, 2020 6:24 pm ] |
| Post subject: | Re: Idler Gear knock/Rattle |
Thanks gtogreen1969 Yeah I will give that a try first. It has 10w40 in there at the moment and good oil pressure 55psi idle and about 80psi max. (brand new engine) There is no knock until engine temp gets to about 60deg so thicker oil might just do the trick. Fingers crossed. The engine builder was very experienced, worked at bmc and owned a mini wreckers so it seems strange that he would build an engine with large idle clearance. cheers Rick |
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| Author: | Bill B [ Mon Feb 03, 2020 11:04 pm ] |
| Post subject: | Re: Idler Gear knock/Rattle |
I agree with gtogreen's comments about heavier oil. Use what you intend running the engine with under normal use. They don't seem to need running-in oils with modern metals - just a couple of early oil and filter changes to begin with. Also, east-west A series often get a noisy idler gear clack (backlash?) at idle when the timing is slightly out. Try a few slight changes + and (-) to the timing. |
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| Author: | MINI66 [ Tue Feb 04, 2020 7:58 am ] |
| Post subject: | Re: Idler Gear knock/Rattle |
G'day Bill Thanks for that I really just used the castrol 10w40 as it was thin (looking at other break in oils they seem thin) and on sale for $20. I must admit that I have only ever used the normal valvolene 20w50 in the past. Timing is 14deg btdc @idle 33deg all in at 3,000rpm but I will no doubt play around with it a bit more once run in. Probably end up with more advance in the end, maybe 16-17 to help the weber transition. Cheers Rick |
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