Rear Axle - Jag Rear overhaul Part 1

One of the jobs I need to be getting on to is the Jag Rear overhaul. I want to have a few of the components chromed and I will use the RPMS prize money I won to do this.

Over the past year I have collected up a few parts....the jag rear that is in the chassis, another one similar so I have spare axles and wishbones, 2 x powerloc limited slip centres and 2 x sets of 47/11 gears (4.27:1).

The powerloc limited slip centres are a unit that goes in the diff and give traction to both wheels. If one wheel starts to spin the clutches inside the diff grab and some of the power gets transferred to the other wheel that has traction, so you get power to both wheels. This means the car gets "drive" and stops skidding.

The gear sets I have will allow me to have the engine and trans turning over at the same revs that they would have at the same road speeds in the original car they came from. I figure Mr Toyota spent millions of dollars refining the engine, trans and computer etc to perform optimally, so if I can replicate that, I should be able to reap the benefit of all that refinement.

In effect then what I have is a whole lot of buckets of bits.

The bucket in the next picture has the powerloc centres and spare sets of gears in it. One of the powerlocs is the unit to the top left of the photo below. It has spiral looking teeth around its edge.

To the right of the photo is one of the sets of gears I want to use. They are currently mounted on a non-powerloc centre or what is known as "open diff". You can see the difference if you look closely. The powerloc is like a solid centre (with clutches inside) whereas the open diff on the right, you can see in the centre of the unit there are some smaller cogs. These are what is known as the "spider gears".

Then I have the diff head thats out of the chassis....

.....and a spare one.

I threw all this into the car and took it all down to Diffs R Us in Otahuhu to talk to Lee Marriner and get his views on which head to use and whether or not I had enough other bits to get a complete unit out of. The verdict was good and I can choose either diff head as they are both suitable casings to use.

In the end I have decided to go with the one that was in the chassis as the mount points for the brake calipers looks like it will be the easiest to work with. That will be the next blog on this topic but in the meantime I have added a couple of videos showing how a diff works and also whats inside a Powerloc diff centre.

This first video explains how an open diff works.

This next video shows the internals of a unit that is very similar to the Powerloc centre from a Jag. You will get to see the clutches I was talking about earlier. Unfortunately I haven't been able to find a video to show how it all works, but in effect the clutches you see in this video "grab" and provide drive to the wheel with traction, rather than letting all the power go out to the wheel with no traction. Hope that makes sense. Other than that the workings aren't too dissimilar to the one in the above video.

Thats it for now, but I will send a few more blogs as I rebuild the Jag rear. Stayed tuned!