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Diff Pegging


Jon White
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Anyone got any experience of pegging diffs? Not necessarily on a landrover - I'm told most commercail vehicles have them as standard!

Before any posts "Ashcrofts do it", sorry, but at the moment fund wont run to paying someone to do it, and being as I've a fair amount of engineering ability (built my own LT77 to series conversion for example) I'm going to have a go at doing it myself.

I'm running 4.7 series cwp's with arb centres, but I keep stripping teeth off of the CWP - that 3 in 2 months so far!

On the same vain, funds wont run to uprated CWP's at the moment either, so my though was that for the cost of a few bits of metal and bolts, and some time (my time is effectively free to me) I'd give it a go.

I've seen the info on ahcrofts website, but am looking for any alternative approaches to this, and any personal experiences (good or bad).

Anyone got anything to offer?

Thanks in advance!

Jon

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Does diff pegging have the same effect as fitting a 4 pin diff??

No, if I understand it correctly the pegging stops the crownwheel moving away from the pinion (and consequent grindings/bangs) so can be done to any diff, and 4 pin diff doesn't improve a non-pegged diff in this sense. Never seen the problem personally though.

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Does diff pegging have the same effect as fitting a 4 pin diff??

They are separate issues. The two common types of diff failure are the stripping of the crownwheel/pinion teeth, and the breaking of the centre part of the diff where the smaller spider gears and cross shaft are. Pegging the diff is meant to prevent the crownwheel from being forced away from the pinion under extreme load. When this happens, the contact area between the crownwheel teeth and the pinion teeth is suddenly reduced and the teeth sheer off.

Two pin diffs have a single centre cross shaft supporting 2 small gears in the diff centre. A four pin diff has a 'four ended' or cross shaped arangement which supports 4 centre diff gears, thereby spreading the loads over more teeth than can be achieved with a two pin diff.

Hope this helps,

Regards,

Diff

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Jon I would be interested in this if you are going to do it.

I run 3.54's at present but its too high, I would like to run 4.7's again but I have a detroit locker and Truetrac.

I have 3 I think 4.7 diffs in the garage and would be interested in converting these to the above and pegging.

I'm only in Churt, you sold my brother a winch as I recall.

I looked at this and thought I might give it a go, but two heads are probably better than one.

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Yeah - no bother Nige - I'm only headley so all of about 3 miles away!

4.7's are the right ratio but they're just not strong enough! I keep twisting front half shafts too.........thats the next job to try and fix for as little outlay as possible!

Jon

Jon, I know its teaching you to suck eggs but in a lot of cases r&p failier is due to a badly built diff, worn geares or goosed bearings. A lot of people instantly blame the Rover design when that's not the real cause of failier. I had my diffs pegged just before I took the truck off the road as I needed to have one of the front ARB serviced and I thought it'f be sensible given I'm planning to run 37" tyres with arround 450 lb/ft of torque.

As far as pegging goes, I think it'll probably help although I think it makes more differance on 3.54 with their thin, flexy, crownwheel. Talking to Ashrofts the thing that makes the process expensive is they weld up the casing to reinforce the area where the studs go through the casing. This is both very specialist work and the welding rods are eye wateringly expensive.

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Jon, I know its teaching you to suck eggs but in a lot of cases r&p failier is due to a badly built diff, worn geares or goosed bearings. A lot of people instantly blame the Rover design when that's not the real cause of failier. I had my diffs pegged just before I took the truck off the road as I needed to have one of the front ARB serviced and I thought it'f be sensible given I'm planning to run 37" tyres with arround 450 lb/ft of torque.

As far as pegging goes, I think it'll probably help although I think it makes more differance on 3.54 with their thin, flexy, crownwheel. Talking to Ashrofts the thing that makes the process expensive is they weld up the casing to reinforce the area where the studs go through the casing. This is both very specialist work and the welding rods are eye wateringly expensive.

Will,

Diffs in all three cases were professionally built, with all parts inspected and new bearings where required. There was nothing wrong with the parts nor the way they were put together.

The 3.54's are stronger than series 4.7's. Its the 4.7's that are inherantly weak.

Jon

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Jon I would be interested in this if you are going to do it.

I run 3.54's at present but its too high, I would like to run 4.7's again but I have a detroit locker and Truetrac.

I have 3 I think 4.7 diffs in the garage and would be interested in converting these to the above and pegging.

I'm only in Churt, you sold my brother a winch as I recall.

I looked at this and thought I might give it a go, but two heads are probably better than one.

....and theres a industrial Milling Machine, lathe and big lumps of off cuts of plate stuff and coffee between both of you :D

Nige

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Interesting Thread.

I am about to sort out my diffs I have ARBs fitted but run Std C/P the gearing is far to high with 35s fitted. I have an Auto box from Ashcrofts fitted to a TD5 90 and all other mods from them as well.

I am thinking of having 4.11 C/P fitted and pegged at the same time, I have not used other companies but noticed they are a lot cheaper for the same job. I think that I will stick with Ashcroft’s as they always do a good job and are easy to talk to.

I think that Pegging is a over kill on Challenge spec vehicles unless you are putting out mega BHP with big tyres, (I’m not) just like to have belts and Braces. :)

Peter

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....and theres a industrial Milling Machine, lathe and big lumps of off cuts of plate stuff and coffee between both of you :D

Nige

Nige,

its more than likely goin to happen a bit further south ;)

u're more than welcome to bring your coffee though :D

i have some tig info u might want a read through at the same time

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The "Ummming" "Arrrring" and Poking with sticks (Non TIG type more Sh***y ones :lol: ) could be my end, whereas the Beggy whinny pleasec an you tig up this lump of steel to this lump of casing WILL be further south I guess too :D

Back OT the CWP I seem to have in the back of my mond are stronger weaker for a selection of reasosns.

1 0 the quality of the metal obviously, but

2 There is something rattling around in my mind which is a factor relating to the size and number of teeth on the pinnion etc, and that the 4.7s are weaker due to this, like surface area / core size on a half shfat.

I'm sure id Dave from Ashcrofts wonders along he'll know what I mean and will make it make sense

3 Flexing - when you apl;ly lots of BHP and torque and tyres grip the CW can flex, if at the same time the pinion is being heavily driven the mesh of the CWP can be pushed apart, and then the pinion strips both itself and the CW of teeth. PINNING the diff by adding a slipper plate means as the CW flexs out it is stopped by the pad, this saving the diff

4 the centre of the diff is completely different, 2 pin (std) are far weaker than either 4 pin, KAM ARB MAXIDRIVE DETROIT lockers, JW has a ARB cenrte 4.7

Not so much Info for JW 9as he knows all of the above and more) but for genral info....

BTW Will absolutely no way was this a badly built diff......

Nige

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Will,

Diffs in all three cases were professionally built, with all parts inspected and new bearings where required. There was nothing wrong with the parts nor the way they were put together.

The 3.54's are stronger than series 4.7's. Its the 4.7's that are inherantly weak.

Jon

I deffinatly didn't mean that, Jon (and Nige), as I know yours are built well. I was making the point that a lot of people break an old, normally 3.54, cw&p with old bearings and blame the standard rover design. I know exactly how weak 4.7's are - I stripped a couple on an old seies I used to drive with a fairly flat 2.25, open diffs and 900 x 16 bar grips.

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Ok, thanks :)

Aside from the aftermarket variations in ratios, it will be a cold day in hell before I go back to LR 4.75's.

I used to check the preload, bearings, CWP every month, and I still did 7 in one year, they were fitted to a detroit rear and arb front. I even did two in one go, that did make a noise :D

I too will be maching my own slipper pads in the diff soon (well as soon as the mills wired in!) I would just put up with the carp ratio, going 3.54 was one of the best things I did.

I beleive King differentials in Bingham, Notts is doing a more crude method of just drilling and tapping a couple of bolts through.

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So Nige, would a 4 pin, pegged (and ARB) diff be the way to go belt and braces using standard rover kit?

Dpends on the axles you have, but yep,

pegged and ARB/ Detroit KAM etc centres are about as good as you'll get (people can argue the pros cons of each manufactuer / suppilier - they all are better than 2 pin std diff !)for a Std LR/RR axle

CWP from Ashcroft, GBR or maybe KAM *same arguing as above - difference is often down to the ratio you need), then theirs shafts STD LR / RR are all poor, go Ashcroft, GKN, MAXuidrive etc again arguementas will be as to which, I have used Ashcroft for some 10+ years and am 100% happy with them, nothing is unbreakable, and these shafts are limites by CV Shafts size etc, then you have the CV issue, Ashcrofts are l;ovely but only do 90s, I run the very eraly GKN RR CVs, and they are one of the strongest made.... and then if as I have you have RR then you have to have a stub shaft, on mine I have Quaiffe stub shafts and drive flanges.

JW has series so very different again, and theres always options to get a FAR STRONGER copmplete std axle ie Tpyota/ Volvo / Nissan / Dana etc, just depends how far you are prepared to go

What is true is that building a stronger LR based axle will costs a lot, and will still be inferior in many ways to some of the USA and other HD axles that you could fit, but its the Ag Factor here that often stops many doing it.

Mioe I expect will break now and again, ...

but with Pegged casing FRT and Rear Ashcroft HD Shafts, Quaiffe HD stubs quaiffe flanges etc plus strengthed casings and ARB 24 spline centres I pray not too often....

HTH

Nige

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