Bumble
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| posted on 17/2/11 at 11:13 AM |
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Help......Diff Noise.......Live Axle
Ok, I'm panicking........I'm nearing completion on my build which I picked up as a "very part built". Last night having
filled up gearbox and diff with their respective oils I started her up and ran it in gear whilst on axle stands. Bit concerned by the noise from the
diff which I video'd and posted here:
http://www.youtube.com/watch?v=P1Kg6nWqA2w
The diff is pretty much the only item on the car that I haven't bought and don't know the history of it. I'm pretty sure it's
a 4.125:1 ratio (having deciphered it from a rusty metal tag attached to it). The half shafts are straight, splines in good order and have fitted new
bearings to them.
Is this noise normal or am I panicking unnecessarily?
Thanks,
Matt
PS - what about the ratio....too low or ok - mainly will be used on road with the odd track day and fitted to T9 5sp?
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MikeCapon
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| posted on 17/2/11 at 11:25 AM |
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To be honest it's difficuly to say much from your video. All I can tell you is that pretty much any car run without load like that makes a
hideous din as all the various fits in the driveline will clatter.
I worked for a while for a Peugeot touring car team and the engine + gearbox man used to like to warm up all the transmission with the car on stands
before qualifying. The first time you heard the car run up like that it was bloody surprising. The various transmission noises were louder than the
(very loud) exhaust.
I'd not panic and wait till you run the car under load. A light application of the brakes may help to kill the clatter but take care.
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blakep82
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| posted on 17/2/11 at 11:30 AM |
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Oil sits in the tubes, round the half shafts etc. When I got my atlas rebuilt (and very modified, I filled with oil, emptied a whole bottle in, left
it to soak through the diff bearings and into the tubes, and topped up again. Have a check, the level may have dropped since you filled it?
edit: having now watched the video, i don't think thats bad. if you think about it, between the gears in there, there's a little bit of
free play, and nothing to stop the crown wheel going a little bit fast and slower than the pinion, so they clatter together. a little bit of brake
should stop it, or even better, a drive on the road
[Edited on 17/2/11 by blakep82]
________________________
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don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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Ivan
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| posted on 17/2/11 at 11:32 AM |
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Can't help you with the diff but from what I have read on here a 4.125 diff is completely the wrong ratio for a BEC although I will be the first
to concede that I know nothing about BECs. Think you might want to do a bit of research.
Re reading your post maybe it isn't a BEC - pse ignore if not.
[Edited on 17/2/11 by Ivan]
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tul214
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| posted on 17/2/11 at 11:36 AM |
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quote:
Originally posted by Ivan
Can't help you with the diff but from what I have read on here a 4.125 diff is completely the wrong ratio for a BEC although I will be the first
to concede that I know nothing about BECs. Think you might want to do a bit of research.
If he is running a T9 gearbox it is not a BEC
Don't panic until you run it on the road with some load on it.
1.6 Raw Super6 sold
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David Jenkins
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| posted on 17/2/11 at 11:42 AM |
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And don't forget that you wouldn't have heard the diff when it was mounted in its original car - it's a lot more exposed in a
Locost, and your ear is a lot closer!
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Mr Whippy
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| posted on 17/2/11 at 11:43 AM |
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or put the calipers back on and lightly press the brakes. I think too that having it on axle stands will make it sound a lot louder than if it was on
it's tyres
did sound a bit like a washing machine with a bolt in it but that might just be the vid Have you had the cover off to give it a quick check
over?
Only real test will be on the road but you'll always hear it whirring away, they’re not silent things. Btw I fitted solid bushes once to my
falcons Cortina axle and the whining noise was deafening but could hardly hear it with the normal rubber bushes, guess what went in the bin
[Edited on 17/2/11 by Mr Whippy]
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Bumble
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| posted on 17/2/11 at 12:08 PM |
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Thanks for the replies so far.
General plan is to first apply some resistance to see if this affects the noise then drain down oil to check for metal etc and then remove cover for a
poke around.
Any comments re: the ratio as I've been told it's too low for road use.
Thanks,
Matt
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blakep82
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| posted on 17/2/11 at 12:13 PM |
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http://www.englishdiff.co.uk/ratios--information.html
click the download file button, and 4.125:1 is listed as a ratio. not sure how it can be 'too low for road use' since it was fitted to
many of fords finest. maybe not ideal for a 7 type, but certainly not impossible to use. the kind of thing i'd say try it before worrying about
it. think mines a 3.44:1 (atlas) i'm going to try it before worrying if its not good enough
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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tul214
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| posted on 17/2/11 at 12:21 PM |
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4.1 will be good for acceleration but might be tiresome on a motorway.
Have a play with this.
Mark
1.6 Raw Super6 sold
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Mr Whippy
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| posted on 17/2/11 at 01:59 PM |
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going to have a play with that when I get home, though the falcon is not a streamlined car...
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Canada EH!
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| posted on 17/2/11 at 03:59 PM |
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Pull the fill plug check that lube is even with the bottom of the hole.
Stick your little finger in to the lube and then look at the lube on your finger with a torch, any shiny bits, a few is not a problem, many are.
Remember your engine is not running smooth at idle and there are all kinds of stop and start motions going on in the drive line from engine to diff,
axle stands magnify the sound.
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big_wasa
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| posted on 17/2/11 at 04:44 PM |
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Hard to tell and as said there will be some back lash noise with no load but it still doesnt sound as smooth as mine did.
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mark chandler
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| posted on 17/2/11 at 07:09 PM |
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If I jack my car up and run with the wheels spinning it sounded horrible until the engine had a bit of a tune then it just sounded bad.
On the road nice and quiet, do not worry its probally just snatching and chattering, on the road it will be either loaded up when accelerating or
de-accelerating when cruising smoothly moving between the two.
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