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If you know the flywheel is 4 thou out and you know the thickness it should be possible to work out how much mass this is, knowing this can you get access to the flywheel to drill ballance holes which remove this mass at the high point? Kevin , the 4 thou is not a problem ,its half the allowable tolerance , the problem is , if you look at this piccy .. You can see how the balancing drillings are all on one side ,and there is a lot of material removed ... i am suspecting this was done to cure a internal imbalance, which i don't have (apart from mentally) , so now its out of balance . i think the thing to do is hoick it off ,and balance it . I did Email bamford rose , who do work with aston clutches , to ask if it was so ,but no reply. regards robert
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Some flywheels are deliberatly out of balance matched by an equal imbalance in the crank which gives a better overall balance, there could be something like this going on.
As you say only real option is to get it balanced.
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glenanderson
Club Retro Rides Member
Posts: 4,270
Club RR Member Number: 64
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That ^^^ is a good point. The imbalance on the flywheel could be deliberate for the transit application. It’d definitely be worth getting it checked out.
It’s hard to be sure, because the camera angle and focal length could be distorting it, but are your prop yokes aligned, and are the flanges on the gearbox and axle parallel? If they’re not, then that will result in vibration, and you’ll just have to live with it if you can’t engineer it out.
Your coupling shaft with one U/J and one CV could be a source of vibes too.
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My worst worry about dying is my wife selling my stuff for what I told her it cost...
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Apr 10, 2019 10:46:09 GMT
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One other thought, is it a live axle on leaf springs? If so with that amount of torque you have it is very likely the springs will be winding up and the axle nose moves up a considerable distance, this will destroy the prop. On the commercial vehicle applications I work on we tend to add extra leaves in the spring to counteract this, a couple of torque reaction links or a full 4 link set up would be even better.
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Last Edit: Apr 10, 2019 10:47:03 GMT by kevins
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Apr 10, 2019 11:23:12 GMT
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That ^^^ is a good point. The imbalance on the flywheel could be deliberate for the transit application. It’d definitely be worth getting it checked out. It’s hard to be sure, because the camera angle and focal length could be distorting it, but are your prop yokes aligned, and are the flanges on the gearbox and axle parallel? If they’re not, then that will result in vibration, and you’ll just have to live with it if you can’t engineer it out. Your coupling shaft with one U/J and one CV could be a source of vibes too. Glen , thank you its nice to see you and Kevin agree with me re the uj and cv joint um , i don't have that on there ? what do have is a rubber donut and a uj , , however with the original clutch i had no vibration from anywhere , so the pre shaft and after shaft are a ok . the uj's are if i remember from the thread on rns , 12 degrees out , but work perfectly well up to 130 mph on the dyno . no vibration at all . oh , its not a transit clutch , its a aston martin db9 twin plate clutch , as shown in the last few pages of the thread . One other thought, is it a live axle on leaf springs? If so with that amount of torque you have it is very likely the springs will be winding up and the axle nose moves up a considerable distance, this will destroy the prop. On the commercial vehicle applications I work on we tend to add extra leaves in the spring to counteract this, a couple of torque reaction links or a full 4 link set up would be even better. Kevin , it already 5 linked as a way to avoid wind up .
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Last Edit: Apr 10, 2019 11:25:34 GMT by ivanhoew
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Apr 10, 2019 12:05:49 GMT
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I had the prop on my lotus out by about 20 degrees for years, when I had it rebuilt (mainly to get rid of the staked joints on one end which were getting stiff) the guy said it would make a massive improvement to put them in line and fixed it, I couldn't tell the difference!
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glenanderson
Club Retro Rides Member
Posts: 4,270
Club RR Member Number: 64
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Apr 10, 2019 12:12:43 GMT
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Sorry. I thought you made the link between the rear engine and the clutch/flywheel housing with a CV one end and a U/J the other. It was a long way back, and my apologies if I’ve either mis-remembered or missed you doing it differently.
My reference to transit was for the flywheel, because I thought that’s what it was off; I know the clutch is an Aston one, my goldfish brain has held on to that (for the time being). 😂
If you had no vibes before, would it be worth considering getting the whole clutch/flywheel assembly checked and balanced? I know there are budgetary constraints, but even mounting it up on a dummy shaft between some vee blocks and seeing what it looks like for static balance would give you an idea whether it’s worth investigating further.
Does the vibration period coincide with a part of the rev range you hit regularly, or can you avoid it?
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My worst worry about dying is my wife selling my stuff for what I told her it cost...
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Apr 10, 2019 17:01:13 GMT
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It’s hard to be sure, because the camera angle and focal length could be distorting it, but are your prop yokes aligned, and are the flanges on the gearbox and axle parallel? If they’re not, then that will result in vibration, and you’ll just have to live with it if you can’t engineer it out. Your coupling shaft with one U/J and one CV could be a source of vibes too. Oh, you beat me to it. Yep, yep I was going to err, to say.... I was... just about... to, ah Gah. Too late now. =)
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Apr 10, 2019 17:04:10 GMT
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re the uj and cv joint um , i don't have that on there ? what do have is a rubber donut and a uj , , however with the original clutch i had no vibration from anywhere , so the pre shaft and after shaft are a ok . the uj's are if i remember from the thread on rns , 12 degrees out , but work perfectly well up to 130 mph on the dyno . no vibration at all . oh , its not a transit clutch , its a aston martin db9 twin plate clutch , as shown in the last few pages of the thread . I mean, yeah... that's kind of why I ... I didn't bother to... errr... make the point, myself, just now because ah, yeah... it's.. I'd already spotted that too. As well. *Whistles*
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glenanderson
Club Retro Rides Member
Posts: 4,270
Club RR Member Number: 64
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Apr 10, 2019 17:26:31 GMT
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As half explained above, the flywheel is from an externally balanced AMV8 - used on a naturally balanced I6 it makes the rotating assembly unbalanced - the solution as above is to machine off the AMV8 balancing drillings. Ah, you see, I thought Robert had made the clutch fit the transit flywheel. That he’d made the entire Aston assembly fit instead had escaped me. V8 vs I6 makes perfect sense.
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My worst worry about dying is my wife selling my stuff for what I told her it cost...
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tristanh
Part of things
Routinely bewildered
Posts: 990
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Apr 10, 2019 18:09:41 GMT
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re the uj and cv joint um , i don't have that on there ? what do have is a rubber donut and a uj , , however with the original clutch i had no vibration from anywhere , so the pre shaft and after shaft are a ok . the uj's are if i remember from the thread on rns , 12 degrees out , but work perfectly well up to 130 mph on the dyno . no vibration at all . oh , its not a transit clutch , its a aston martin db9 twin plate clutch , as shown in the last few pages of the thread . I mean, yeah... that's kind of why I ... I didn't bother to... errr... make the point, myself, just now because ah, yeah... it's.. I'd already spotted that too. As well. *Whistles* You see @quatermass, these young uns are soaking up knowledge from your Scimitar thread, you have them well educated.
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Whether you believe you can, or you cannot, you're probably right.
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Apr 10, 2019 18:18:49 GMT
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either way, its not a straight 6
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Apr 10, 2019 19:25:57 GMT
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As half explained above, the flywheel is from an externally balanced AMV8 - used on a naturally balanced I6 it makes the rotating assembly unbalanced - the solution as above is to machine off the AMV8 balancing drillings. um acherly its a db9 which is a v12.
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Apr 10, 2019 19:29:46 GMT
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I mean, yeah... that's kind of why I ... I didn't bother to... errr... make the point, myself, just now because ah, yeah... it's.. I'd already spotted that too. As well. *Whistles* You see @quatermass, these young uns are soaking up knowledge from your Scimitar thread, you have them well educated. I'll raise them right even if it means I have to drag them up by their ears.
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Sounds like you've got an exhaust leak, mate. *knowing wink *possible additional teeth sucking noise
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, however with the original clutch i had no vibration from anywhere , so the pre shaft and after shaft are a ok . the uj's are if i remember from the thread on rns , 12 degrees out , but work perfectly well up to 130 mph on the dyno . no vibration at all . . Is the vibration apparent when being revved while stationary in the 4-4.5k range or is it only when driving? Just trying to eliminate potential issue with the final drive shaft which, in the pic, looks possibly to be a little out of sync... i.e angle out of gearbox not equal to angle in to diff.
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Last Edit: Apr 11, 2019 14:09:27 GMT by ivanhoew
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Apr 11, 2019 20:22:07 GMT
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I had a chance to test my theory today, about the bottom feed gas supply possibly helping no5 fire properly , here is the data log of this afternoons run beside a previous side gas entry run .... that seems to be working .which is nice . regards robert
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Last Edit: Apr 11, 2019 20:22:54 GMT by ivanhoew
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video of the clutch saga ..
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Apr 12, 2019 19:25:59 GMT
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So , since i have not done much this week , and been a bit of a fopping pantywaister , i decided to take the gearbox out ,,,again .. it was grumbling at me "you keep takin dat low down no good front injin out , why you no take me out homey hu huuhuh..? " which was a surprise. so out it came and the clutch was on the bench in no time .. to balance it i have a plan involving these items ... a motor.. a doughnut connector flange .. my vfd off the flowbench .. a bowl of water .. and ,last but not least , where would any plan be without a " LAZZZZZOOORRRRRR" i am sure that's all pretty self explanatory , i am looking forward to this experiment a lot . regards robert
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Last Edit: Apr 12, 2019 19:29:18 GMT by ivanhoew
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Apr 12, 2019 20:12:02 GMT
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this is gonna be good!
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