Thread: Life of Puma Rear Diff's

I thought you had already bought one of those you bute props that chook got

Originally Posted by dullbird

I thought you had already bought one of those you bute props that chook got

The new ashcroft diff requires the shortening of the rear shaft, the dodgy ones Drover and I bought from that less than reputable person were double cardon shafts for the front.

Mine is sitting destroyed on my garage floor after just 3000km with the manufacturer refusing to do anything about it.

On another note unfortunately there have been some problems with my diff and it seems another one in Melbourne. These problems seem to revolve around a machining error during manufacturing.

I have just received a great email from Dave Ashcroft explaining the problem and what he plans to do to fix it. He also acknowledged that I plan to leave on a trip next week and assured me that it will not affect the reliability of the diff, it just makes a bit of noise on overrun. Dave has also offered to pay all of the additional costs incurred by this which for me with portals is a bit as to get the diff in and out the portals have to come apart.

I am very impressed with the way Dave has responded to the problem, we all know that these things can happen but the difference is how the manufacturer responds.

I thought I would post this as i am sure everyone is going to ask for reviews.

Originally Posted by dullbird

I thought you had already bought one of those you bute props that chook got

Hey Lou,

This is one occasion that breaching AULRO's rules on naming dodgy rip off merchant posing as reputable businesses would be a service to our members.

Tempting but I'll behave......grrrrrrrrrrrr

Originally Posted by Drover

Hey Lou,

This is one occasion that breaching AULRO's rules on naming dodgy rip off merchant posing as reputable businesses would be a service to our members.

Tempting but I'll behave......grrrrrrrrrrrr

Yep I have had to try very hard to restrain myself from naming and shaming.....

Lemmings anybody.

I have done about 100km on the new diff so I thought I would post a first impression post. As previously mentioned the diff has a little fault which Dave Ashcroft is on top of and I have to say whilst a noise on overrun is clearly there it is no where near as bad as I thought it was going to be.

I thought that we had previously got rid of most of the backlash but this new diff makes the most amazing difference to the way it drives, pulling away from lights and changing gears feels positive and I don't have to be conscious of the driveline the whole time any more.

I am very impressed despite the small machining fault. I will update again once I have a few more KM on the clock.

Just a FWIW on prop shaft diameters.

Measured the 130, rear prop OD is 70mm.

Nissan Patrol coil cab ute, rear prop is 91mm OD. (and quite a bit shorter, we won't mention UJ size either....) The Effie shaft is in the neighbours shed, but IIRC it's 4" or larger.

Yes, a Patrol drives through the rear diff on road, but still...and as John mentioned, a number of 130's experience vibration problems from the rear shaft 'whirling', which is the phenomenon you get when the shaft reaches its critical speed.

The smaller the diameter and longer the shaft the lower the critical speed and in theory form the charts I've seen a 70mm mild steel shaft 58" long would have a critical speed somewhere around 4-4500RPM, well above what a 130 would see normally, yet they wobble or whirl.

Originally Posted by rick130

Just a FWIW on prop shaft diameters.

Measured the 130, rear prop OD is 70mm.

Nissan Patrol coil cab ute, rear prop is 91mm OD. (and quite a bit shorter, we won't mention UJ size either....) The Effie shaft is in the neighbours shed, but IIRC it's 4" or larger.

Yes, a Patrol drives through the rear diff on road, but still...and as John mentioned, a number of 130's experience vibration problems from the rear shaft 'whirling', which is the phenomenon you get when the shaft reaches its critical speed.

The smaller the diameter and longer the shaft the lower the critical speed and in theory form the charts I've seen a 70mm mild steel shaft 58" long would have a critical speed somewhere around 4-4500RPM, well above what a 130 would see normally, yet they wobble or whirl.

70mm I didn't think they were that large.

The tail shaft from my 120 is only 50mm, same as for a rangie with 100" WB.

79 series cruisers are about 80mm.