Thread: Fitted an Ashcroft Locker

I had my Ashcroft Torque Biasing LSD fitted last week, I agree, the machining is exquisite.

Originally Posted by Capstan

I just fitted an Ascroft Locker to the rear of my 1985 Rangie along with some 24 spline axles. I was very impressed with the machining, very pretty. Ritters set up the crown and pinion for me but I put it back in.

About time! No all you need is some decent tyres and you can come out on some REAL trips with us.

Originally Posted by isuzutoo-eh

I had my Ashcroft Torque Biasing LSD fitted last week, I agree, the machining is exquisite.

How's it go? Whats the difference between it and a trutrac?

I've never driven a Trutrac'ed vehicle to compare...going from open diffs though the steering is a little heavier, but not a lot. Mine is in the front of my County. Ask me next week and I'll have forgotten its there. Unfortunately the install coincided with my steering damper failing so I had second thoughts for the first few days but it isn't the ATB diff's fault.
From what Ashcrofts told me, Trutracs have three side gears, the Ashcroft ATB has 6, so is effectively much stronger. It also worked out cheaper than the same TT. The ATB isn't available for the Salisbury/yet.

Just looking for front diff options, not sure whether to go locker or lsd thingy. Stick it in and forget about it is the bit i like

Originally Posted by isuzutoo-eh

I've never driven a Trutrac'ed vehicle to compare...going from open diffs though the steering is a little heavier, but not a lot. Mine is in the front of my County. Ask me next week and I'll have forgotten its there. Unfortunately the install coincided with my steering damper failing so I had second thoughts for the first few days but it isn't the ATB diff's fault.
From what Ashcrofts told me, Trutracs have three side gears, the Ashcroft ATB has 6, so is effectively much stronger. It also worked out cheaper than the same TT. The ATB isn't available for the Salisbury/yet.

Trutrac has 3 gears left, 3 gears right and 2 side gears, never touched an ashcroft yet

Hi Mark, if you don't mind me asking what did it cost and what are the advantages over a locker? And don't LSD's get that wind up problem happening when travelling in reverse? Probably stupid question I know, but I've only got limited knowledge on diffs. Oh, and what's the torque biasing about?
cheers Gerald

Gerald, thats a clever question.
A selectable locker such as ARB, Maxidrive, Jacmac or Ashcroft solidly locks the right and left axles together when selected, or runs as a normal diff when not selected.
Detroit and Kaiser lockers are called auto-lockers, these lock the left and rigt axles together at all times, but when one wheel needs to travel faster than the other, such as around roundabouts, the axle unlocks via a strong ratchet-these lockers can make clicking noises as the ratchet unlocks momentarily. Importantly, no axle can move slower than the crownwheel, but can move faster. Automatic lockered vehicles sometimes get described as 'skipping' around corners, as the locking mechanism locks and unlocks.
Limited Slip Diffs allow the left and right axles to move at different speeds at all times, they are never solidly locked across. This is the same as an open diff. With an open diff, if one wheel has no traction, ie in the air or slippery mud, that wheel will spin and the other wheel won't get any torque.
The LSD has internal gadgetry, of which there are two varieties. This gadgetry allows the slipping wheel to spin, but biases the amount of spin. I gather most LSDs are biased 60:40 or thereabouts. That means the slipping wheel gets 60% of the torque available, whilst the wheel with grip gets 40%. Net result is you get 40% of available torque on the ground to keep you moving. Much better than nothing. As I understand it the freely spinning wheel actually needs some resistance to make the internal gadgetry do its thing otherwise it acts as an open diff.
The two types of internal gadgetry are torque plates, much like clutch plates, which when warmed up by slipping, grab together to sort-of lock the axles together. This type needs a lot of adjustment to keep working effectively, as the 'clutch' plates wear. These diffs require LSD oil too, so another flavour of oil to keep in stock. Hiluxes and some nissans come with plate type LSDs from factory.
The other LSD type is what Trutracs and the Ashcroft ATB (Automative Torque Biasing) diffs are, which is a geared diff. These have worm gears instead of the bevel gears that open diffs have. One of the characterisitics of a worm gear, is they are hard to reverse drive. Ie, using a wormwheel to drive a worm gear is very inefficient, there is a lot of friction, and the forces applied aren't applied in the most effective direction.
This all means that the inefficiently driven worms allow a small amount of speed difference between the two axles, but the torque required to have one side's worm gears completely free spinning is phenomenal, so part of the torque goes the easier route, through the wheel that has traction. The torque is biased towards the free spinning wheel, but there is still that 40% or so available to the wheel with traction. Unlike plate (clutch) type LSDs, geared type LSDs don't ever require adjusting, and use standard gear oil.

If that made sense, I will teach you japanese whilst speaking pig romanian with a pikey accent.

Oh yeah costs, 370 squid had it landed on my doorstep.