Thread: Life of Puma Rear Diff's

Originally Posted by wagoo

Doesn't such a diff already exist in the form of the McNamara Hypoid? All the Rover ratios plus all the Toyota Hilux ratios to choose from. It would be interesting to know how many have been sold over the years to gauge sales potential for an Ashcroft alternative, although one could add around 50% to those figures to account for Mcs attitude.
Bill.

I was going to add, how much longer will they be in production. I have heard that even with money in hand it can be hit and miss if you get one due to personality

When still very new I had a strange noise develop from the right rear. After many trips to the dealer and new seals, assemblies, bla, bla, it turned out that the right rear shaft of the diff was completely rusty. No problems in the 12k km's since its replacement though.

Originally Posted by First90

When still very new I had a strange noise develop from the right rear. After many trips to the dealer and new seals, assemblies, bla, bla, it turned out that the right rear shaft of the diff was completely rusty. No problems in the 12k km's since its replacement though.

where was it rusty and where was this causing noise?

Originally Posted by wagoo

Doesn't such a diff already exist in the form of the McNamara Hypoid? All the Rover ratios plus all the Toyota Hilux ratios to choose from. It would be interesting to know how many have been sold over the years to gauge sales potential for an Ashcroft alternative, although one could add around 50% to those figures to account for Mcs attitude.
Bill.

you are right Bill,

this got me thinking, there are many similarities but I am thinking we may have over engineered the ring and pinion, the one we have started with is the ford 8.8 which is massive and causes problems with getting to all 10 of the mounting bolts meaning an adapter ring needs fitting to the housing then the diff fitting to this, this would work but is not very neat, it would be nice to not need the ring.

the toy 8" is way stronger than the P38 and rover diff due to being hypoid so we may not need anything much stronger than this,

rather than take an existing R & P and adapt it to fit I think we need to start from scratch and see how strong we can get in terms of offset and hypoid distances but keeping within the existing 10 mounting bolt pattern,

the problem with any design is working out where to draw the line, if you try to make it cover all possible combinations it's get too complicated and expensive, ie just 24 spline, 24 and ford 31 or 24, 31 and 35 spline, to make it cover the 35 spline will mean bigger side gears and journal bearings etc which will add cost just for the few that will have this option as you will also need new hubs, stubaxles, drive flanges etc. also whether to make the diff casting able to also be machined as a rover replacement, ie not just the P38 110 rear

I think most sales would be a straight drop in 3.54 replacement with locker and HD 24 spline shafts for the 110 rear P38 type,

the 24 spline shafts aren't really the problem here, it's the diff thats the weak point

Dave

Originally Posted by ashtrans

you are right Bill,

this got me thinking, there are many similarities but I am thinking we may have over engineered the ring and pinion, the one we have started with is the ford 8.8 which is massive and causes problems with getting to all 10 of the mounting bolts meaning an adapter ring needs fitting to the housing then the diff fitting to this, this would work but is not very neat, it would be nice to not need the ring.

the toy 8" is way stronger than the P38 and rover diff due to being hypoid so we may not need anything much stronger than this,

rather than take an existing R & P and adapt it to fit I think we need to start from scratch and see how strong we can get in terms of offset and hypoid distances but keeping within the existing 10 mounting bolt pattern,

the problem with any design is working out where to draw the line, if you try to make it cover all possible combinations it's get too complicated and expensive, ie just 24 spline, 24 and ford 31 or 24, 31 and 35 spline, to make it cover the 35 spline will mean bigger side gears and journal bearings etc which will add cost just for the few that will have this option as you will also need new hubs, stubaxles, drive flanges etc. also whether to make the diff casting able to also be machined as a rover replacement, ie not just the P38 110 rear

I think most sales would be a straight drop in 3.54 replacement with locker and HD 24 spline shafts for the 110 rear P38 type,

the 24 spline shafts aren't really the problem here, it's the diff thats the weak point

Dave

Most certainly Dave!!!!!

JC

Originally Posted by rick130

Diff type number.
There are several versions of the H233 too, bolt sizes have changed, etc.

They come in high and low pinion and were/are used across a lot of models.
For a high pinion diff, think GQ/GU front diff centre which I think are the H233B.

...

Pretty much. They are fitted to front (high pinion version) and rear (low pinion version) of Nissan GQ and GU patrols. Some patrols have the massive H260 rear diff.

AFAIK 233 is the diameter of the crown wheel/ring gear in mm (rover is 8.5" so approx 226 mm, but much weaker). They are available in a good range of ratios.

Serg, I don't know the carrier bearing size off hand, but can say it is not an issue.

My interest in whether they would suit the P38 diff is because I am not using an LT230 transfer in my 120, and I need a centred (or small left offset) diff - currently I have a flipped 105 series LC rear diff, but QLD only allows 50mm increase in track (I hope this will change with adoption of national code of practice).

Originally Posted by ashtrans

you are right Bill,

this got me thinking, there are many similarities but I am thinking we may have over engineered the ring and pinion, the one we have started with is the ford 8.8 which is massive and causes problems with getting to all 10 of the mounting bolts meaning an adapter ring needs fitting to the housing then the diff fitting to this, this would work but is not very neat, it would be nice to not need the ring.

the toy 8" is way stronger than the P38 and rover diff due to being hypoid so we may not need anything much stronger than this,

rather than take an existing R & P and adapt it to fit I think we need to start from scratch and see how strong we can get in terms of offset and hypoid distances but keeping within the existing 10 mounting bolt pattern,
[snip]

Dave

Dave, the Toyota high pinion 8" centre was a popular substitution for the front diff centre here, but reading the boards it sounds like quite a few found out what the Toyota 79 and 80 Series blokes found it, it goes bang in reverse.

Originally Posted by rick130

Dave, the Toyota high pinion 8" centre was a popular substitution for the front diff centre here, but reading the boards it sounds like quite a few found out what the Toyota 79 and 80 Series blokes found it, it goes bang in reverse.

The 4.3:1 reverse cut a horribly weak, as fitted to naturally aspirated 78/79 diesels

The 4.1:1 arent as bad, but still.....

The go is the jacmac cast 3rd housing as it bolts in and fits a Hilux Hypoid, normal crown wheel and pinion and has clearance for the drag link, I have one on the bench I scabbed up a while ago

Its also a 3.54, Jeff had a heap of these made up, they really are a good thing

Although, I was just going to stick some trutracks in my P38, but seeing as its going to be around 500HP and either 427ci or 350 and supercharged, I'm liking the sound of the H233 conversion