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Differential trouble

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Igordiver Avatar
Igordiver Igor Duerloo
Kapellen, Antwerp, Belgium   BEL
1968 Triumph Spitfire MkIII "Thin Lizzy"
1977 Porsche 928 "The Shark"
The day after returning from France, the Spit got stuck on a short trip. Engine was running great but it seemed as if the handbrake was on. The car wouldn't move anymore after we had heard a loud grinding sound coming from the back. It wouldn't drive but we were able to push it over it's "resistance point." After a few revolutions the resistance would come again and once pushed over that point it would roll a few turns again before resistance came back.
Took out the differential last Sunday and first of all there wasn't a drop of oil left in it despite a decent refill before leaving for Normandy.
Turning the output flanges is allright but it seems that the input flange doesn't always turn with it. When spinning the input flange I can feel that resistance again, if I spin it back a bit a can continue again.
See attached video's.
Any advice on this? Is it worth opening it up to see what's wrong or is it best to go for a rebuild diff?

Kind regards








"Alterius non sit qui suus esse potest"



Edited 1 time(s). Last edit at 2017-10-31 08:51 AM by Igordiver.

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Smithisretired Avatar
Smithisretired Michael Smith
Wells, Maine, USA   USA
Certainly worth opening up. Sounds like a seized pinion bearing.

clshore Carter Shore
Beverly Hills, Florida, USA   USA
How do you say 'It's Toast' in Flemish?

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Igordiver Avatar
Igordiver Igor Duerloo
Kapellen, Antwerp, Belgium   BEL
1968 Triumph Spitfire MkIII "Thin Lizzy"
1977 Porsche 928 "The Shark"
Here in Antwerp we say : Het is naar de kloten. ("This sucks ball's" in slang I believe. kloten = testicles) cool smiley



"Alterius non sit qui suus esse potest"



Edited 3 time(s). Last edit at 2017-10-31 08:57 AM by Igordiver.

clshore Carter Shore
Beverly Hills, Florida, USA   USA
In reply to # 1495114 by Igordiver Here in Antwerp we say : Het is naar de kloten. ( kloten = testicles) This lesson is free of charge smileys with beer

Haha, thanks, I get your meaning.
Open it up and see what's gone wrong, there may be a lot of parts that can be re-used in a rebuild.
In the best case, only the bearings will have failed, and the gearset will be OK.

Igordiver Avatar
Igordiver Igor Duerloo
Kapellen, Antwerp, Belgium   BEL
1968 Triumph Spitfire MkIII "Thin Lizzy"
1977 Porsche 928 "The Shark"
Replacing the pinion bearing is a PITA I believe?



"Alterius non sit qui suus esse potest"

Azoth Shane G
Los Angeles, CA, USA   USA
In reply to # 1495116 by Igordiver Replacing the pinion bearing is a PITA I believe?

It's a lot of work and requires some specialized tools (dial gauge, bearing puller, inch/lb torque wrench, and a press is really helpful). If you open up the diff you may find some other things that need refurbishment, like the thrust washers in the sun/planet gears. On some diffs these are made from a fabric that can wear out over time. Those are easy to replace though.

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Tonyfixit Avatar
Tonyfixit Tony M
Duncan, British Columbia, Canada   CAN
Those bearings don't sound quite right eye popping smiley

Open it up and see how things look. it could be that a new set of bearings, oil seals and thrust washers will put it back in order.

Drill the case and add a drain plug while you are at it.

Igordiver Avatar
Igordiver Igor Duerloo
Kapellen, Antwerp, Belgium   BEL
1968 Triumph Spitfire MkIII "Thin Lizzy"
1977 Porsche 928 "The Shark"
In reply to # 1495166 by Azoth
In reply to # 1495116 by Igordiver Replacing the pinion bearing is a PITA I believe?

It's a lot of work and requires some specialized tools (dial gauge, bearing puller, inch/lb torque wrench, and a press is really helpful). If you open up the diff you may find some other things that need refurbishment, like the thrust washers in the sun/planet gears. On some diffs these are made from a fabric that can wear out over time. Those are easy to replace though.

Well I did have a go at it this morning. Most specialized tools I do have but not the spreader to open up the diff case. Been beating away at it with hammer and chisel for an hour. A rebuild unit will cost me 900$. Better choice, decided it's not worth the hassle.



"Alterius non sit qui suus esse potest"

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clshore Carter Shore
Beverly Hills, Florida, USA   USA
In reply to # 1495464 by Igordiver
In reply to # 1495166 by Azoth
In reply to # 1495116 by Igordiver Replacing the pinion bearing is a PITA I believe?

It's a lot of work and requires some specialized tools (dial gauge, bearing puller, inch/lb torque wrench, and a press is really helpful). If you open up the diff you may find some other things that need refurbishment, like the thrust washers in the sun/planet gears. On some diffs these are made from a fabric that can wear out over time. Those are easy to replace though.

Well I did have a go at it this morning. Most specialized tools I do have but not the spreader to open up the diff case. Been beating away at it with hammer and chisel for an hour. A rebuild unit will cost me 900$. Better choice, decided it's not worth the hassle.

NO,NO,NO !!!
STOP IMMEDIATELY !!!

You are doing it wrong !!!
Despite the apparent crudeness, these are precision machined parts.
Beating with a hammer is guaranteed to RUIN them.

READ THE WORKSHOP MANUAL FIRST !!!

The SPREADER is only used upon ASSEMBLY, and even then is a luxury that makes it easier to reassemble.
I've been working on these cars for nearly 50 years, have NEVER used spreader, have never SEEN a spreader, have never HEARD of anyone that HAD a spreader.

Remove the stub axles, then the case bolts, then the unit comes apart easily, held only by the gasket.

Carter

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, British Columbia, Canada   CAN
I DO use a spreader, but it is not very sophisticated


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20170904_154252.jpg

clshore Carter Shore
Beverly Hills, Florida, USA   USA
I use a fine file to break the edge at the parting line, creating a small 75-80 degree bevel.
Place the the spacer shims into the bearing saddle, and then slide in each outer bearing race.
A couple of light taps with a hammer and in they go.

Another trick is to heat the housing casting in an oven, and chill the carrier assembly, but
I've never had to resort to that, the bevel method works just fine for me.

If you use a spreader, take care NOT to spread too far, you will tweak and ruin the housing.

moltenmetal Avatar
moltenmetal Paul Martin
Toronto, Ontario, Canada   CAN
1975 Triumph Spitfire 1500 "E-Fire"
The local British car mechanic everyone swears by will do the bearings and seals in a diff for about $500 CDN- a lot less than a rebuilt diff costs. So it's my hope that mine won't need new gearing- it's just noisy and the crown pinion bearing is likely done. The thrust bearings are definitely done...

clshore Carter Shore
Beverly Hills, Florida, USA   USA
In reply to # 1495519 by moltenmetal The local British car mechanic everyone swears by will do the bearings and seals in a diff for about $500 CDN- a lot less than a rebuilt diff costs. So it's my hope that mine won't need new gearing- it's just noisy and the crown pinion bearing is likely done. The thrust bearings are definitely done...

Well, hope springs eternal in the heart of Spitfire owners ...
... but I fear that you will be disappointed, as geartooth wear is the primary source of noise.

Bearing elements roll against each other, gearteeth touch and slide against one another.

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, British Columbia, Canada   CAN
It would be nice to look inside.

I don't know where the oil went, but I guess it is possible that the crown wheel was still picking up a little oil while the bearings were running dry.

The noise I hear (and it does sound nasty) sounds like vey dry bearings.

But..........my toughts are.........this diff could well be beyond economic repair. Sending it out for a bearing job (unless the guy can first give you an honest assessment ) could be throwing good money after bad.

A home rebuild? The hammer and chisel bit made me think the owner may have the wrong temperament for such work (it requires lots of patients )


That said, perhaps another used diff is the way to go?

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