Diff oil change, metalic bits

GJUK · Post by **GJUK** » Sun Jul 17, 16 12:17 am

Hi,
I had a 8 3/4 diff rebuilt on the dart ~400 miles ago, steady ish driving and changed the oil today. I expected some metallic bit but perhaps not this much...

Does this look normal? The diff sounds fine...

Brand new crown and pinion went in the casing, which was fully cleaned out prior to build.

Thanks,

J

GJUK · Post by **GJUK** » Sun Jul 17, 16 12:19 am

the fluid drain pan is like 2ft across to give you an idea of scale. My finger is normal size

Pete.S · Post by **Pete.S** » Sun Jul 17, 16 11:20 pm

H
The diff wasnt rebuilt and new ring gear was bolted on to it!!

I suspect you cone style SG is giving up with the burnouts!

GJUK · Post by **GJUK** » Sun Jul 17, 16 11:41 pm

Sorry Pete, I can't remember what you did. I know new CWP were bolted in.
Sure grip was whatever was in the diff - what was the oil like when you stripped it down? I guess if it was like this before the change of gears it might indicate the suregrip.

Anyone know signs of suregrip failure (apart from lots of metalic bits in your oil!)

... I thought 8 3/4 diffs were quite strong :-/

GJUK · Post by **GJUK** » Mon Jul 18, 16 10:26 am

Out she comes...

To my untrained eye it looks okay, turns fairly free.

The halfshafts however, the bearings near the hub ends (carrier bearings?) are very stiff. lots of the metal bits appear brass/gold in colour.

wiped towards the camera what was on the surface of the gear:

All bearing I have encountered spin freely, the ones on the halfshafts turn but with quite a lot of force (covered in oil, though they may be; I can no spin them with all my force using one finger, I have to grasp them with my hand to turn them...)

Any thoughts please?

Thanks,

Pete.S · Post by **Pete.S** » Mon Jul 18, 16 7:00 pm

Well wear pattern on ring and pinion is fine (all bar the scores due to the bits of metal in the oil).

You have new green style non adjustable bearings on the shafts these are stiffer than normal adjustable bearings !!
These are shaft bearings. The carrier bearings are each side of the diff..

Jon i offered to collect the axle from you free of charge and strip inspect and report and replace anything free of charge if its anything we have done..

From your description of, it sounded fine etc, we can say the gear mesh/backlash was good and this is confirmed by the wear pattern in the pictures you have posted.

I suspect its the diff ..

As you have decided to strip it yourself with limited knowledge im afraid the balls in your court. Most of the time the probleme solving is in the detailed disassembly by someone who knows what to look for.

GJUK · Post by **GJUK** » Mon Jul 18, 16 8:51 pm

Hi Pete,
Yep I know, that was very kind of you.

I've not taken the diff to bits, just out of the casing.
------------

As I am impatient and I want the car for mopars, I took the diff to Andy Robinson today to get it checked out, says the wear pattern of the diff was good, everything set up correctly. The larger bits (which were the worrying parts) appear to be from the casing after it was shortened which are (so I'm advised) very hard/impossible to clean properly. Then when they are on the road the vibration/movement cause some of the bits to free up and hey presto.

Also check the half shafts and they all appear fine with the shaft (thanks for correcting me Pete) bearings.

So good news, worth a trip down there and have my mind put at ease, bought some oil from him. Nice guy, great service.

Pete.S · Post by **Pete.S** » Mon Jul 18, 16 9:59 pm

Was the SG itself stripped and checked?

The axle cases are cut on a water cooled horizontal band saw set at an angle so no debris goes in the axle case. These are not dry cut with a grider etc to prevent exactly that??

Cannonball · Post by **Cannonball** » Mon Jul 18, 16 10:15 pm

If its the suregrip with cone affair rather than clutch plates that looks to be the problem, typical i just sold a new sg,

GJUK · Post by **GJUK** » Mon Jul 18, 16 10:37 pm

Pete.S wrote:Was the SG itself stripped and checked?

The axle cases are cut on a water cooled horizontal band saw set at an angle so no debris goes in the axle case. These are not dry cut with a grider etc to prevent exactly that??

Hi,

No he just did an inspection of the unit; tested the unit with some white paste to see how the CWP match, checked for wear. Spent about 20 minutes on it. I have to go by what he suggested (who am I to question him!) but it does sound possible that the cone unit slipper is on its way out.

small amounts of debris on this kind of suregrip is normal I was told, they do wear against each other. Also the gears finding their 'happy place' creating some more particles are also normal, most of the bits in the oil he did not seem to mind, the larger bits were of concern.

I guess I'll bolt it all back up together, give it another 100 miles then drop the oil again and see what is happening - If there is a load more Bananarama! in there; I'll upgrade the suregrip to some North Korean unit made for 6000hp.

Pete.S · Post by **Pete.S** » Mon Jul 18, 16 10:57 pm

Yes well as i have said to you jon in pm's im sure it the cone suregrip chewing itself up.

The metal deposits are straw coloured as metal has got super hot. Normal wear is dark metallic.

See you at mopar nats

GJUK · Post by **GJUK** » Mon Jul 18, 16 11:16 pm

I may bring the Dart in parts in my daily car.

GJUK · Post by **GJUK** » Tue Jul 19, 16 4:02 pm

Well now I see how it works!

one of the cones almost bottoms out on the housing, used tipex to see if contact was being made and it was:

other than the cone area, which has wear I can't see anything else really bad.

GJUK · Post by **GJUK** » Tue Jul 19, 16 4:08 pm

GJUK · Post by **GJUK** » Tue Jul 19, 16 4:08 pm

oops double post