There's a very faint clunking which I think is coming from the back of the car, more noticeable when decelerating, but probably only because the engine is quieter. Any ideas? Diff? Bearings?
Cheers.
Noisy Diff?
Started by
_oikurtman_
, Aug 31 2006 10:45 AM
22 replies to this topic
#2
_Herne_
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Posted 31 August 2006 - 11:25 AM
Probably not the cause but just might be. Have you checked the simple things like universal joints? Cheap and easy fix if thats the problem and certainly the first place I would start looking at with clunking noise coming from the rear of the car.
Cheers
Herne
Cheers
Herne
#3
_RCK-914_
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Posted 31 August 2006 - 11:39 AM
I had the same sort of clunking noise comming from the back of the every time I put it into gear, replaced both uni's good as now, got them from repco $38 for the pair and it only took about 1 1/2 hours do do the job.
#4
_oikurtman_
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Posted 31 August 2006 - 12:58 PM
Just did my uni's. Not all new bits as a couple of the caps got damaged but from what i could tell the pieces i did use were all fine.
Any more ideas?
Cheers.
Any more ideas?
Cheers.
#5
gtrboyy
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Posted 31 August 2006 - 01:06 PM
Probably too much backlash in your diff if you say the uni joints are ok,otherwise check everthing is still tightened up & no mounts are stuffed.
#6
TerrA LX
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Posted 31 August 2006 - 03:46 PM
probably backlash in the diff, but you refer to damaged caps, new ones, what gives?Just did my uni's. Not all new bits as a couple of the caps got damaged but from what i could tell the pieces i did use were all fine.
Any more ideas?
Cheers.
#7
_oikurtman_
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Posted 31 August 2006 - 06:26 PM
when i put the new caps in, they went in slightly crooked and got wrecked when i pulled them back out. the front uni was all new bits but the back one was, (from memory), new spider, 2 new caps with new roller bearings, 2 old caps with old roller bearings.
had a look at the diff this arvo. no movement in wheels. when i turn the tailshaft one way then the other there is a significant clunk in the diff. obviously there will be some sort of noise but the diff clunk was more pronounced than the auto clunk. that normal? yes its full of good looking oil.
also, when the wheels spin opposite ways the diff makes a noise, but no apparent noise when just turning one (both simultaneously was a bit hard).
Cheers.
P.S: whats backlash?
had a look at the diff this arvo. no movement in wheels. when i turn the tailshaft one way then the other there is a significant clunk in the diff. obviously there will be some sort of noise but the diff clunk was more pronounced than the auto clunk. that normal? yes its full of good looking oil.
also, when the wheels spin opposite ways the diff makes a noise, but no apparent noise when just turning one (both simultaneously was a bit hard).
Cheers.
P.S: whats backlash?
Edited by oikurtman, 31 August 2006 - 06:27 PM.
#8
gtrboyy
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Posted 31 August 2006 - 10:32 PM
Backlash in the diff is when there is too much freeplay between the pinion & the crownwheel in the diff.
#9
_oikurtman_
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Posted 01 September 2006 - 11:15 AM
change the diff centre?
i have a 3.08 in the shed...
mine is apparently a 2.78 but it really doesn't feel like it. when the auto guy built the box he thought it felt like a 3.36 or something.
3.08 is better all rounder anyway right?
Cheers.
i have a 3.08 in the shed...
mine is apparently a 2.78 but it really doesn't feel like it. when the auto guy built the box he thought it felt like a 3.36 or something.
3.08 is better all rounder anyway right?
Cheers.
#10
_Chamois hatch_
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Posted 01 September 2006 - 04:25 PM
if its slow of the line then yes it has a 2.78,
i unfortunatly run a 2.78+trimatic and its so slow of the line its emabarrasing, and like you, when i slow down and the trimatic shifts down to 1st gear, i get a clunk from the rear of the car........any i have brand new unis.....so i doubt its unis, i would look into the whole backlash issue.
cheers
john
i unfortunatly run a 2.78+trimatic and its so slow of the line its emabarrasing, and like you, when i slow down and the trimatic shifts down to 1st gear, i get a clunk from the rear of the car........any i have brand new unis.....so i doubt its unis, i would look into the whole backlash issue.
cheers
john
#11
_oikurtman_
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Posted 01 September 2006 - 07:20 PM
how do you check for back lash?
thinking I might change the centre to 3.08...
Opinions? Blue 253, trimatic, 3.08?
Cheers.
thinking I might change the centre to 3.08...
Opinions? Blue 253, trimatic, 3.08?
Cheers.
#12
TORLX8
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Posted 01 September 2006 - 08:07 PM
Listen to all o..pinions & don't be scared of backlash. 
.........sorry, bad diff joke, couldn't resist.
.........sorry, bad diff joke, couldn't resist.
#13
_oikurtman_
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Posted 02 September 2006 - 07:59 PM
like you said, bad diff joke!
i noticed the clunking is there even when rolling (both directions) when the engine is off.
???
cheers.
i noticed the clunking is there even when rolling (both directions) when the engine is off.
???
cheers.
#14
_oikurtman_
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Posted 04 September 2006 - 01:32 PM
My auto guy tested the diff ratio today. Definitely a 2.78. But he said because its a commdore trimatic, designed to spin 175/75/R14 and i have 235/60/R13, putting a 3.08 will probably make it scream even more on the highway...
If the 2.78 diff has got backlash though, is it best that I change it? How can I find out if its ok or not?
Cheers.
If the 2.78 diff has got backlash though, is it best that I change it? How can I find out if its ok or not?
Cheers.
#15
TerrA LX
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Posted 04 September 2006 - 03:59 PM
i say just install the 3.08 if you have it, its a more performance friendly ratio anyway.
#16
FastEHHolden
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Posted 04 September 2006 - 06:59 PM
the commodore trimatic is the same as the torana trimatic..its top gear is still one to one...he is playing with himself.
#17
_SSHatch_
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Posted 04 September 2006 - 07:54 PM
There is that little difference between the two tyres. You would be hard pressed to actually notice the difference it made to the car with that small of a difference in the rolling diameter in the tyres.
235/60R13 = 612.190mm Diameter
175/75R14 = 618.109mm Diameter
Just cause 60 is a smaller number than 75 doesnt mean the tyres will be smaller.
235/60R13 = 612.190mm Diameter
175/75R14 = 618.109mm Diameter
Just cause 60 is a smaller number than 75 doesnt mean the tyres will be smaller.
#18
surfmaster
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Posted 04 September 2006 - 08:30 PM
3.08:1 will give you bettr take off from standing start but will be a little heavier on the islamic spring water. If you can get the 2.78:1 overhauled I would be doing that, it is (IMHO) the better ratio with the trimatic.
#19
gtrboyy
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Posted 04 September 2006 - 11:17 PM
Check the diff that you plan on putting first to save some drama.Spin the diff flange by hand to make sure it's not noisey,teeth aren't chipped or pitted.
Also hold the the crown wheel with your hand & then move the diff flange to check how much backlash.
This will only tell you if the diff has an obivous,it could still be noisey once in the car though.
I'd go the 3.08:1 diff for mainly highway use & a 3.36 ratio if you do suburban use & want it quicker down low.
Also hold the the crown wheel with your hand & then move the diff flange to check how much backlash.
This will only tell you if the diff has an obivous,it could still be noisey once in the car though.
I'd go the 3.08:1 diff for mainly highway use & a 3.36 ratio if you do suburban use & want it quicker down low.
#20
_oikurtman_
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Posted 05 September 2006 - 08:43 PM
thanks for the feedback fellas.
what i don't understand though is why it still revs so high on the highway, despite the 2.78 diff. I'll be fitting the tacho soon so i'll post some actual figures up to see if anyone else has similar rev - km/h setups. Maybe it's meant to be like that, i don't know, but it just feels like its revving a bit much.
Cheers.
what i don't understand though is why it still revs so high on the highway, despite the 2.78 diff. I'll be fitting the tacho soon so i'll post some actual figures up to see if anyone else has similar rev - km/h setups. Maybe it's meant to be like that, i don't know, but it just feels like its revving a bit much.
Cheers.
#21
_oikurtman_
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Posted 06 September 2006 - 10:49 PM
pulled the 3.08 out today and checked for backlash as gtrboyy said. it did have a tiny bit of movement when i held the crown wheel. All teeth looked fine.
Is it meant to move or not at all?
Cheers.
Is it meant to move or not at all?
Cheers.
#22
gtrboyy
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Posted 08 September 2006 - 06:52 PM
A little bit of backlash is fine,it is meant to move a little bit.
#23
_on the limit_
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Posted 11 September 2006 - 06:34 PM
you should have between 8 thou & 12 thou backlash.pulled the 3.08 out today and checked for backlash as gtrboyy said. it did have a tiny bit of movement when i held the crown wheel. All teeth looked fine.
Is it meant to move or not at all?
Cheers.
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