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Diff Pan Replacement

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Hmmmmmmmmmmmmm……………. I suspect that Dan or Jez will provide an answer to this. ;)

At the moment during my axle building, I noticed that the rear casing really requires a new diff pan. Welding is not a problem for me, however, this weld needs to be oil tight, and I only want to do it once……… so, what’s the preferred methodology,

1) I am more comfortable with a continuous weld bead to ensure that its oil tight, so ……….. to avoid distortion can I tack the new pan every ¾ inch and then run one continuous bead ………. or,

2) weld it the same as a thin panel and put in say 2 inch beads 180 degrees apart to avoid the distortion problem. This seems messy to me.

My preferred method is the first, and probably I will go back to the old fashioned circular motion of the torch rather than the normal saw tooth stitching pattern. :rolleyes:

Just so you can all have a smile, I’ll post up the job when finished. :D


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I wouldn't worry about distortion.

So long as it's well tacked before you hit it it will be allright.

In Addition to jez's tips a good 3/4" overlap on all your stop-starts helps as well.

To avoid any porousity and to get a really clean weld, before you tack the new dif pan on, give the entire area you are about to weld a goods toasting with a gas axe or a blow torch, this will help to burn off any ep90 that's still there.

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Right I’ll give it a go on sat /sun…………

No gas axe (used to have one but the house insurance got a bit heavy, even with port-a-packs), but I’ll preheat with the propane furnace ;) ……… and use the Jez method of gas backflow ………….. thanks guys.

Watch this space………


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I can see the advantages of SS sewer capping on the front …………….and if I did rock crawling I could also see the need of a stronger rear, however, this is the rear and it will be reasonably protected by the diff guard. Unless I reverse into a rock or a stump :rolleyes: , its pretty safe at the backend.

How many rear pans have you holed ? I’ve only ever holed one front before, but never even dented a rear………… it’s the underside of the casing that gets most abuse.

Interestingly the axle is 24 spline from a disco and it looks like the rot has been caused by road salt getting trapped under flaking paint. The front axle was mint and received a coat of paint last night………… tonight will see the new Teflon swivels built up onto the axle ready for fitting.

The reasons above are good enough to go for the standard pan (that’s probably put the kiss of death on it) ………. and then refit the rockslider diff guard which also protects the diff flange UJ, and importantly gives more protection to the bottom of the diff casing.

The welding isn’t really an issue …………… its more the thought that it has to be a perfect seal that makes it seem a more demanding task ……. however, following good advice here I will burn off, tack, grind tacks, preheat, backflow and get on with it. If the front build continues at a pace then I might get the welding done this weekend. ;)


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You are going to have to strip the casing to get a decent clean / weld.

Rear Casings are as cheap as chips, why not just but another and shove it all back on with a guard ?

Nige :blink:


The casing is stripped and ready to go ………… both axles are having complete rebuilds before fitting …………. then later in the year a visit to Dave Ashcroft will empty the wallet for the important bits. Whilst its in the stripped state and set up in the workshop, it just seems sensible to weld a new pan on.

I have decided that axles are f’kin heavy …….they fall off of axle stands and hurt your toes……. trapping your thumb between the diff and the floor makes a nasty mess of your thumb nail………..and cleaning them is a filthy job …….. Ho hum........... :rolleyes:

Al………. thanks for the offer ……… but I already have the replacement pan (SPI)…........during my ‘pan investigation’ (oooooer yuk) …….. it is evident that pans are available in 2mm (OEM spec), 3mm, 4m & 5mm, ranging in price from £25 to £79 ….. .. so thoughts must be varied as to what is best.


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I bought a 8" N.B, C/S, Schedule 40 pipe cap(reffered to as a 'sewer cap' by the american's on pirate etc) from:

Gas & Fluid Fittings Ltd

Unit 10-11, Bellknowes Industrial Estate, Inverkeithing, Fife KY11 1HZ

Tel: 01383 416268

It was about £35 if I remeber rightly. However I was doing it again I would probably step down to a shecule 30 cap as the schedule 40 is 12mm thick! I forgot that the forged fittings are thicker than the coresponding pipe wall thickness.

I then machined the internal bore of the pipe cap out and reduced it's height leaving a suitable weld prep on the end. We cut off the old cap completely and tacked on the new one. However the clearance between the ring and the cap is only 2mm either way, so we trial fitted the diff. Once fully welded we then used a grinder to remove some of the weld root internaly in the ring cut outs to give added clearance. However I was using a KAM 4.75 ring and pinion which is slightly bigger in diameter than the over 3.54.

The end result is in the picture below:


I think that there are clearnace issues with the panhard rod if you do this at the front, but this may be with the as bought cap, it may fit if it is reduced in height. I went a slightly different root at the front and bent up some 50 x 10mm bar and some 6mm plate to make a diff pan. However it is far easier to fit the sewer cap.

Front dif pan:


This is well worth doing in my opinion - rocks that i inadvertantly hit in the past that resulted in a well known cornish diff pan protector being severely bent and the ring ripping a hole in the diff pan before leaving a tooth pattern on the back of the diff pan now either get demolished or pushed out of the way....


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  • 2 weeks later...

At last I got around to welding on the new pan,

The old pan was not as bad as first thought ………. But I had the new pan anyway so what the hell……

Cut off the old pan and grind out the old pan flange as this will have oil behind it


Following Dans suggestion ………….. give it 30mins of propane to make sure any oil is burnt out and the casing has some preheat,

Then carefully line up the new pan and solid tack. The alignment is critical and takes a while. The solid tacks are then ground back.


Then propane for 30 mins to provide some preheat. Following info from Jez......Back feed the underside with gas and then hit it with the mig. My eyesight isn’t what it used to be, so I had to stop to move position …….. so there are 3 start stops in the weld. :rolleyes:


Here is a close up of the weld just so you can all take the p!ss ………….not the prettiest of my welds but very functional……. you are allowed to mark out of ten :P ……. A Will Warne weld is a one :D …….. and a Jez/Dan weld is an eleven. B)


I then filled the pan with paraffin overnight ……… and just had one small damp patch….. which was soon sorted.

The spring perches looked past their best, so they also got renewed.


Mr LR has some quality problems :rolleyes: ……… some git missed this porous weld on the axle tube,


However, it was soon cleaned up and fixed.


Thanks for those that offered advise and help ………. I got there in the end and the axle is now fitted.


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