English Axle Rebuild
Right I decided to change my diff ratio recently from a 4.1:1 to a 5.1:1 because I wasnít the happiest with my cars acceleration and general ability to take off the line. Iíve compiled pictures and data that Iíve gathered along the way to try make it easier for any of ye out there that want to either change a C.W.P in and English axle or just install a LSD.
Firstly to my ratios
Gear box Ratios Ė Quaife S/C 4 Speed Rocket
4th 1.0 Rev Limiter 7500rpm
Speed in Mph
Final Drive - 4.1:1
Final Drive - 5.1:1
I want to make clear that I am no expert in this field and I donít take any responsibility for anyone who wrecks their diff. This is not a how to guide but rather a how I done it guide.
Anyone you ask says you need specialised tools to do the job and you would have to bring it to someone who knows what they are at. Well this is true but we are in a recession and not everyone has loads of money to pay someone to do the work for them so my method is using some home made tools.
The Tools you will need as are follows.
1. A Good Vernier calipers with a depth gauge
2. A torque wrench
3. Socket set (13,16,19)
4. Spanners (13,14)
5. A spring balance
6. 150mm of Key way steel
7. Prop shaft Flange wrench (Home made)
8. Diff carrier wrench (Home made)
9. A dial gauge and magnetic stand (optional)
10. Hydraulic Press
11. Surface grinder (Machine shop)
12. Hammers, chisels, punches etc
1. Tran x LSD Unit Ė
2. C.W.P Set 5.1:1 (Burton Part No. CWE51) ₤245
3. Diff Bearings Full Kit Ebay ₤50 or
(Burton Part Noís AXENG1,2,3,4,5) ₤101
4. Halfshaft bearings (Burton Part No. QWB148C) ₤44
5. Spring Balance (Argos Part No.074/3893) Ä9
6. Key way Steel (Local Motor factors) Ä9
7. Engineering Blue (Local Motor factors) Ä10
8. 2L Castrol B373 (Local Motor factors) Ä25
9. Dial Gauge (Burton Part No. DRA51830) ₤22 or
I got mine local motor factors Ä28
10.Magnetic Stand (Burton part No. DRA37340) ₤22 or
I got mine local motor factors Ä34
Carried out in 6 Steps
Step 1. Taking the diff out of the axle.
Step 2. Stripping the unit.
Step 3 Ė Measuring the Pinion depth.
Step 4. Taking out the old pinion.
Step 5. Pre-loading the bearings.
Step 6. Refitting the Crown wheel and Diff.
Step 1. Taking the diff out of the axle
Jack the back of car and support securely on axle stands. Undo the wheel nuts and remove the drum from the rear brake assembly.
There is a special tool for removing stubborn drums but I find a lump hammer and chisels quite effective for freeing them up. Simply hammer three evenly spaced chisels between the drum and back plate then a few taps of the drum with a lump hammer usually gets it off although it may take a while and a lot of swearing.
Once you get the drum off the half-shaft is next to go. It is secured using 4 bolts through the back plate to the axle. Once these are undone the back plate will usually need a few taps of a rubber hammer to free the half shaft from its housing. Care should be taken not to damage the brake assembly of brake pipe fittings. Once the half shaft carrier bearing is free the half shaft will come out through the centre of the back plate. This procedure should then be carried out on the opposite side.
Disconnect the prop flange, then undo the nuts fixing the pigs head to the axle. I fitted blind diff nuts I got off eBay when I was building my axle as they leave it very handy for taking the unit off the axle. Remember the unit is full of oil so you will need something to catch the oil Approx 1.1L once you undo the diff nuts.
Step 2. Stripping the unit
So the diff is out of the axle and on the bench. Next step is to strip it.
Its probably handiest to loosen the crown wheel bolts while the unit is still assembled. If you fit a socket to one bolt like so it locks up the diff and you will be able to loosen the other bolts then.
Next mark the bearing caps and side bearing adjusters I found a centre punch the best. This is done to identify their appropriate side at the reassembly stage. Then undo the bearing cap bolts and remove the bearing caps along with the side adjusters.
The Crown wheel and diff can then be lifted out of the pigs head leaving the pinion as shown
A standard diff unit with crown wheel attached.
The old crown wheel can be removed and new one fitted and torqued up. A rubber mallet is handy at this stage as itís a tight fit and you donít want to do any harm be hitting the teeth. You could also bake the new crown wheel in the oven for 20 minutes to expand it and it will fit easier.
If your just fitting a LSD you can skip the next three stages and just fit your old crown wheel to the new LSD unit. Its probably best to fit new carrier bearings to the unit at this time. You could try them in the oven like the crown wheel if that doesnít work they will press on easily with a hydraulic press.
Step 3 Ė Measuring the Pinion depth
The pinion depth is set using a measurement of 83.57mm from the centerline of the crown wheel to the underside of the pinion. There are tools for setting this height but I decided to give it a go myself. I bought some key way steel from my local motor factors cost Ä9 then drilled a hole in it so I could feed my depth gauge from my Vernier through it.
Using my Vernier calipers I measured the distance from the top of the key way to the bottom of the bearing carrier housing. I then checked the other side as well to make sure they were the same. Luckily this housing measured the same depth both sides. This gave me a depth of 39.06mm-6.38mm for the thickness of the key way gave me 32.68mm the distance from the top of the machined face to the bottom of the bearing carrier face.
I then measured the bearing race itself which gave a measurement of 65.10mm half this is 32.55mm. (32.68 vs 32.55) This gave me a correction distance of -0.13mm for my pinion depth.
In the picture shown I was measuring another unit where there was a difference in the heights of the machined face on both sides so I had to put a feeler gauge under the lower side to get an even measurement
I then used the same technique to measure the depth to the pinion from the housings machined face. This gave me a measurement of 50.02mm Ė 0.13mm = 49.89mm. If your accurate with this procedure and take your time you should be able to get accurate results.
Step 4. Taking out the old pinion
To take out the old pinion the flange nut has to be undone holding the prop flange on and pinion in place. I made a tool out of some scrap angle iron for holding the flange while undoing the nut. The nut will be fairly tight so you will probably need an extension to get enough leverage
Its made to suit both mk1 and mk2 escort flanges.
Next remove the flange hand tighten the diff nut back on and press out the pinion. The two bearing races, outer bearing and oil seal will be left in the housing with pinion, inner bearing collapsible washer removed. If you are changing the pinion bearings then the bearing races should now be removed along with outer bearing and oil seal. If your re-using the bearings then the races can be left in place and the oil seal and outer bearing removed.
The collapsible washer can also be reused once the centre rib is tapped out but I had a new one so fitted it along with new bearings.
I also had to make a jig out of 3mm angle to press off the inner bearing. This fits around the pinion bearing and allows it to be removed without damaging it.
Once the inner pinion bearing is pressed off the pinion assembly will look like this. If new bearings are being used the shim should be measured and it with new inner bearing should be pressed unto the new pinion. The old pinion and new pinion thickness should also be measured and noted. The new pinion should then be fitted back into the pigs head along with the new collapsible washer and the new outer bearing pressed on.
Note: The pinion should be supported fully while the outer bearing is pressed on to ensure it is fully pressed on.
Step 5. Preloading the bearings
A new oil seal should also be fitted at this stage unless the old one was ok. The prop flange should then be re-fitted and the nut tightened down in full. The next stage will involve crushing the collapsible washer to set the preload. Donít worry the flange nut will not be over-tightened using a ratchet it will take a fairly big torque to crush the washer. A second pair of hands will be advantageous at this time. The nut should be slowly tightened and the preload (torque taken to turn the pinion in free motion) measured using a spring balance.
Video: Using a lb.in torque wrench but its still gives you good idea of the processhttp://ie.youtube.com/watch?v=8APYO2sZyJU
The spring balance (Argos Ä9) should be attached to one of the holes in the prop flange and the force required to turn it measured off the scale. Alternatively an inch pound torque wrench could be used. The torque setting is 25 lb.in, I calculated this to be a 7kgs force for a mk1 prop flange and 8kgs for a mk2 one. The difference being the distance from the centre line of the pinion being different.
Once the preload is set the pinion depth should be checked again as before. I got a depth of 83.49mm to the back of the Pinion. This measured 0.08mm to high for a required depth of 83.57mm. The pinion then has to be stripped as before and the pinion shim machined by 0.08mm. I got a local machine shop to do this and it cost Ä15 to get it surface ground. http://www.driveandtraction.co.uk/25501.html
can also supply you with machined pinion shims for around ₤6.00
Note: The rib of the collapsible washer will have to be hammered out or a new one used on second assembly.
The pinion then has to be re-fitted as before and the depth checked. If your measurements were taken accurately the depth should now be 83.57mm
Step 6. Refitting the Crown wheel and Diff.
With the pinion now in place and height set the next step is to refit the crown wheel and diff unit. The unit should be placed back into the pigs head and bearing caps refitted to their correct side. The side bearing adjusters should be adjusted in until there is very little play left between the crown wheel and pinion. One adjuster moves the crown wheel away from the pinion and the other moves to towards.
I made a tool for tightening these adjusters. Simply a piece of flat with two bolts fitted at the correct spacing.
I also found it handy for holding the assembly in place to drill my bench and bolt it down.
The backlash is next to set. This is the clearance between the crown wheel and pinion. I set mine to 0.16mm. For setting this I used a dial gauge and magnetic stand. If you donít have one of these you can also use a piece of solder wire. If you feed the solder wire in between the two gears and then measure the compressed piece of solder you will get the clearance.
With the dial gauge and magnetic stand fixed to the side of the housing the crown wheel can be rocked and the clearance/backlash measured of the dial gauge. The backlash is increased by moving the adjuster furthest away from the crown wheel and decreased by moving the side closest the crown wheel. These should be tightened Ė (tight is the best way to describe it).
This should be checked using either method at 3-4 different places around the crown wheel and the locking tabs then bolted on.
The next advisable step if you have changed the pinion is to Ďblueprint Ď the gears this is done using engineers blue. This is an ink that is put on the gears to see how they are meshing I put it on but mustnít have done it right because all I could see was blue everywhere.
So thatís her all reassembled with a new gasket fitted and ready to go back into the car
Taken from the Mk1 Escort Twincam workshop manual
Crown wheel to diff casing bolts 68-75 Nm
Differential bearing cap bolts 61-68 Nm
Locking Tab Bolts 16-20Nm
Diff to axle housing Nuts 34-41Nm
Half shaft bearing retainer bolts 20-24Nm
Prop Flange bolts 20-24Nm
Pinion Bearing Preload- New bearings (Half these values for old bearings)
20-26lb.in including oil seal drag
7kg- Mk1 Large Flange
8kg -Mk2 Large Flange
Oil Capacity 1.1L use Castrol B373 for Tran-X LSD
Note : Remember to Torque everything and use Loctite.
Iíve put a bit of time into producing this and I hope it will be of help to some of ye Ford heads out there. Also if anyone has anything to add please do as Iím only learning to and have compiled this to the best of my knowledge.