mistergrumpy
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| posted on 12/2/08 at 05:58 PM |
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Duff Diff?
Been having problems with putting my car into gear. It was just jerking and stalling so I altered the cable but same so I've had it on the
stands and did it. There's an awful noise from the diff when the engines on tick over. If I accelerate the noise goes but when I come off it
sort of seizes and stalls the engine. Also the passenger wheel doesn't really turn. I can manually turn the passenger wheel which turns the
drivers wheel but turning the drivers wheel don't move the passengers wheel. Is my diff duff?
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james h
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| posted on 12/2/08 at 06:04 PM |
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I am no expert in these matters, but from your description i would say yes.
I cant think of any other reason for one wheel turning more than the other
James
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jambojeef
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| posted on 12/2/08 at 06:08 PM |
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Obvious stuff to check:
Oil in the diff?
Right oil in the diff?
Right amount of oil in the diff?
All bolts done up properly - nothing slipped?
Angle on prop ok? UJs not out of phase or binding?
All these ok?
Geoff
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mistergrumpy
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| posted on 12/2/08 at 06:16 PM |
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Well:
Yes
Yes
Yes
Tight but not overly so, nothing slipped though
All seems okay
But even giving it welly and spinning the prop. the passenger wheel still don't turn properly just kinda wanders.
Something else. The driveshafts-both of them-have kinda play in them in that I can move them from left and right somewhat, feels like just - oh
I've just got it. The driveshafts came off a 7.5" diff so they'll be smaller eh? Sh1t  Righto then anyone around Bolton
got some driveshafts off a 7" diff.
[Edited on 12/2/08 by mistergrumpy]
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daviep
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| posted on 12/2/08 at 06:28 PM |
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You really need to pull offthe drums or take the pads out if its discs before trying to diagnose any diff issues. Symptoms sound more like a tight
brake than anything else. Running any vehicle on stands tend to sound strange.
If you can't get in to gear without stalling sounds more like a clutch problem? Is the clutch definately clearing properly?
Davie
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mistergrumpy
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| posted on 12/2/08 at 06:32 PM |
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I think it is the driveshafts mate being too short for the 7" diff. The longer one is just engaging with the gear but the shorter one just
isn't. I can move the shafts back and forth, squashing the UJ's in effect and the shorter one does feel to have too much play. I bet the
horrible noise is the teeth catching but not engaging.
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daviep
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| posted on 12/2/08 at 06:36 PM |
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Doesn't really explain your problem with stalling when trying to select gears?
Keep us posted.
Davie
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mistergrumpy
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| posted on 12/2/08 at 06:49 PM |
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Yeah. Hmm. Can anyone confirm that the 7" shafts are longer than the 7.5" ones. Honestly it's getting ridiculous. I have:
3 diffs,
2 sets of driveshafts,
2 sets of wheels,
2 propshafts,
spare bodywork at the moment,
2 steering bosses,
2 gear knobs.
been through:
3 dashes
2 sets of wishbones
2 sets of shocks,
2 fuel tanks,
2 batteries
3 chargers
2 rivet guns
Lots of water hose, fuel hose, nuts and bolts
I can almost make another bleeding car!
[Edited on 12/2/08 by mistergrumpy]
[Edited on 12/2/08 by mistergrumpy]
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britishtrident
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| posted on 12/2/08 at 07:29 PM |
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You have to stop jumping to conclusions and go back start to diagnose in a systematic fashion.
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speedyxjs
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| posted on 12/2/08 at 07:35 PM |
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Duff Diff
Tell your diff to stop drinking 
sorry
How long can i resist the temptation to drop a V8 in?
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delboy
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| posted on 12/2/08 at 10:51 PM |
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Are you using push in shafts? There are two different diameters of shaft depending on the diff, could you have a 26 spline shaft in one side and a 23
spline shaft in the other? You need to have mixed them up when breaking more than one car, but it is possible.
Also with lobro shafts the ones from an LSD are different from those for a standard diff.
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mistergrumpy
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| posted on 12/2/08 at 11:03 PM |
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No I'm on bolt on shafts that were taken off a 3:92 7.5" 4x4 back end and I've put them onto a 7" diff. I do however have a
push in diff and shafts spare
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NS Dev
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| posted on 13/2/08 at 08:23 AM |
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If its off a 4x4 then its not a 7.5" diff. It might have a 7.5" wide casing but the only sierra diff to be 7.5" (as in crownwheel,
which is how they are referred to) is the 2wd cosworth, and you can't have mixed the shafts up there because they use larger cv joints, 108mm OD
instead of 100mm OD.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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NS Dev
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| posted on 13/2/08 at 08:24 AM |
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PS 7" diff shafts are 25 spline, 7.5" are 28 spline, I'm having some big ones made to order right now in fact
[Edited on 13/2/08 by NS Dev]
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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mistergrumpy
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| posted on 13/2/08 at 09:29 AM |
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Oh God don't say they have different splines too!I think you're right in that the diff they came off does have a 7.5" case measured
across the top.Still,regardless of the splines because I used the hubs off this back end too,I just need the actual shaft that bolts in to be a little
longer.I was told the back end came off a G reg 4x4 Sierra by the scrappy Off to the scrappy again then!
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mistergrumpy
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| posted on 13/2/08 at 02:25 PM |
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Well I now think its my diff. I've taken it out and if I turn the drivers side flange by hand I can hold the passenger side still. Its like that
side isn't connected. I can't get the back off to inspect the heads just round off.Rubbish 
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daviep
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| posted on 13/2/08 at 09:02 PM |
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Why are you looking at the diff when the original problem was the engine stalling when trying to get gears?
Q1 Can you select any gears without the engine stalling (when the driveshafts are connected and wheels on the ground)?
Q2 Did you ensure the propshaft was jammed when you tried turning the driveshaft flanges?
Keep us posted
Davie
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mistergrumpy
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| posted on 13/2/08 at 09:11 PM |
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Thanks for taking the time Davie.
I am looking at the diff because of the graunching noise that first came from it yesterday and today after disconnecting the driveshafts I turned the
propshaft by hand and only one of the outputs is turning.
Going to the original problem then as you say:
Q1. No
Q2. Did I ensure it was jammed? Erm, well no. As it stands now today I took the diff out looked at it puzzled and put it back. The input now
turns the drivers wheel perfectly but very faintly turns the passenger wheel intermittently. If I put the pressure of only one finger on it, then it
just stops. Turning either wheel by hand does not affect the other wheel.
Edited to suggest. Shall I start the engine then try to grip the prop and stop it by hand whilst it disconnected from the diff. This would prove the
faults not at the engine end?
[Edited on 13/2/08 by mistergrumpy]
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daviep
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| posted on 14/2/08 at 12:10 PM |
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Ok back to basics of things which an open diff can/will do in normal circumstances
Turning the propshaft WILL cause only 1 output to turn, both may MAY turn but but by design the shaft with least resistance will always turn
first/fastest
Turning a halfshaft by hand will cause either the opposite halfshaft to rotate in the opposite direction if it is free or it may cause the propshaft
to rotate.
There are two ways to do a quick check of the diff.
1: Jack up both wheels put the car into gear (this is to jam the propshaft) and then by hand rotate a wheel. The other wheel should rotate in the
opposite direction.
2: Again with the wheel jacked up and the front wheels chocked start the engine and select a gear. If only one wheel is turning try to stop it
(carefully) this should cause the other wheel to start rotating.
If you have a sticky brake or even just one brake adjusted up a bit tighter than the other then the free wheel will always spin.
My first guess would still be a stuck clutch going right back to the begining
Keep us posted
Davie
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mistergrumpy
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| posted on 14/2/08 at 04:16 PM |
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I've spent the day tinkering and what I've just discovered is that the brakes were sticking on one side. When they've been sprayed
its clagged up the faces and the pads are not moving back and forth. I've cleaned them and hey presto both wheels turn now when I turn the prop.
Just having some grub then I'm going to put it back together then try to engage a gear and see if it'll run. Cheers Davie, it helps just
to talk things over with a fresh head,
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