Jump to content
Click here if you are having website access problems ×

Titan LSD Rebuild


aerobod - near CYYC

Recommended Posts

With my 2012 S3 R400D at 8 years old and 34,000km of which about 5,000km has been track days and the preload on the LSD below 20lbft, it is time for a rebuild as my main winter project this year.

Although there are various methods of removing the diff, the method I use is to remove one wheel and the hub, brake disc, ear and driveshaft on that side. The A-frame and rear anti-roll bar also need to be removed to drop the diff. I have the car stored in the winter on a steel frame that is 1.5m above the ground but is up against the wall on the left side, so this method works well when the car is high enough.

After the right rear wheel was removed, the A-frame was removed, making note of the number of shim washers on each side:

0E651DEA-1B99-4E02-BDBC-A60F03782AF3.thumb.jpeg.ee0b4f797957c6c703cd2e4ea111685f.jpeg
 

The end links on the anti-roll bar were disconnected by removing the locking clip on the spherical joint attached at the hub carrier end, the four bolts attaching the anti-roll to the chassis tubes were then unbolted and the bar was extracted out the right side:

8CD1A068-A2E7-4034-99C1-FC4777268D4D.thumb.jpeg.a6566d642193610a4a306e58a29ff505.jpeg

The brake caliper was then unbolted at the sliders and tie-wrapped to the coil spring (I have the flexible rear brake lines, if not the brake pipe needs to be carefully bent to lift the caliper off the brake disc):

3E21A4CC-8E46-4255-B3FA-954EC179C94B.thumb.jpeg.246d5e6d54193922c6ba169d5e54b233.jpeg

After removing the two rearward hub carrier nuts that also secure the ear to the deDion tube, together with the two rear bolts that attach the ear to the deDion tube and unscrewing the speed sensor and moving it out of the way, the driveshaft, brake disc, deDion ear and hub can now be extracted, the two left hand ear attachment bolts are shown screwed loosely in place after removal, so I don't misplace them, something I tend to do with most bolts as I work:

A5AC34EC-616D-4C84-BE24-D87D317D91D2.thumb.jpeg.d624f2d508b8f7ed7a32573a71b1c544.jpeg

The driveshaft bolts are now removed, I place a conventional Allen key in the bolt above the one I'm loosening to stop the shaft rotating as I use the hex socket key with my ratchet and an extension:

EA476125-E5E1-4924-9E38-B2BD1241E364.thumb.jpeg.8b5e6cf7d732ac1dfa3fe900df550aae.jpeg

The lower diff carrier bolts are now loosened, making note of any shim washers between the chassis and carrier, but kept hand threaded in place until the diff is lowered:

7C74A619-C08B-4A9A-8BAD-757DD687B3A3.thumb.jpeg.02b7dd8850144d99c07754ec8899ac59.jpeg
 

Now the top carrier bolt is removed, making note of the shims on each side between the carrier and chassis. My bolt came out fairly easily with a few light taps from a mallet and a rod inserted to drive the bolt out. The diff can now be lowered with your equipment of choice. I used my wheeled tool box with a hydraulic floor jack, using it's natural arc to move the diff sideways as it was lowered, enabling the left driveshaft to be extracted from the diff, but left in place:

BA8A3FA1-090A-4559-BC4A-97ADB5F29788.thumb.jpeg.e322eddd80b0b1133f655002e07e41bb.jpeg

With the diff on the bench, the top carrier bolt, 6 hex bolts and top Allen bolt are removed and a thin blade inserted at the top to break the sealant bond to remove the cover:

DE674FB2-101C-4C26-A5D4-12B713A72DE2.thumb.jpeg.e25aaa92bcb8b3e1d3d7f9d1f3fa6ec7.jpeg
 

The side seals can now be removed, preferably with a seal hook tool to avoid any contact with the bearing. A large pair of circlip pliers is now needed to remove the locking circlip. Be careful to mark these clips, they have a specific thickness on each side to give the correct crown wheel and pinion mesh. My driver's side (left side being in Canada) circlip is marked as 3.44mm thick, my passenger/right side is 3.62mm thick. After removing the circlip the outer bearing races can be extracted using finger pressure and sideways movement of the crown wheel and LSD, no tapping  or levering required on my diff:

D59117FD-4A11-441D-81B3-9144C319B9F5.thumb.jpeg.5cecfc84e291e3ab9ba40f1044f479a3.jpeg
 

After both external races have been removed the crown wheel and LSD can be carefully rotated and extracted:

D940452D-85A0-474A-AEBD-1D4635187ABC.thumb.jpeg.dff29ef39d864e1b767c78ec82ce1ec7.jpeg
 

The 6 Allen bolts holding the LSD cap in place can now be removed. Make note of the alignment dot on the cap (it is obscured by the ratchet in this picture, but you can see the matching dot on the LSD casing just below the ratchet head). The cap is a fairly tight fit, so three of the Allen bolts can be used in the threaded holes to lift it against the casing by tightening them gradually in sequence.

F37B9D7E-5FAD-46EA-AE29-D95D8B47707E.thumb.jpeg.db360c0c61ccb6c56ef08bc401ada43e.jpeg

Now the guts of the LSD can be extracted, laid out in order, cleaned and inspected. The parts order in mine are as follows, bearing in mind the number and thickness of shims can vary, listed from left-hand side (closest to casing cap):

- Thrust shim for diff gear, diff gear Belleville washer, diff gear thrust washer (with the 2 tabs, depressed face towards gear).

- Clutch pack Belleville washer, clutch pack shim, 1st clutch pack steel disc (6 tabs), 1st clutch pack friction disc (carbon or sintered), 2nd clutch pack steel disc, 2nd clutch pack friction disc, 1st LSD cup/cage (marked as L.H.).

- Left hand diff gear, 4 spider gears with 2 cross shafts, right hand diff gear.

- 2nd LSD cup/cage (marked as R.H), 3rd clutch pack friction disc, 3rd clutch pack steel disc, 4th clutch pack friction disc, 4th clutch pack steel disc, clutch pack shim, clutch pack Belleville washer.

- Diff gear thrust washer (depressed face towards gear), diff gear Belleville washer, thrust shim for diff gear.

The ramp angles for my diff are either 30/90 or 45/60, depending on which depression the spider gear shafts are placed in, I will probably stay with 30/90 for most aggressive locking on acceleration and zero on deceleration:

C67D7217-88A0-4B41-ADF1-389154B5DB8D.thumb.jpeg.c4150131ee1a36571cda90970e2b39ad.jpeg

My inspection found the following:

- All ball bearings, races gear teeth  and sliding surfaces are clean, bright and show no noticeable wear.

- There was some "paste" from friction plate wear on the bottom of the diff case and in the nooks and crannies of the cups/cage, but not evident elsewhere.

- One friction plate on each side was almost totally worn out, but the other friction plate on each side had only a small amount of wear.

- Both of the clutch plate Belleville washer were in good condition.

- Both diff gear Belleville washers (the small ones) had wear on the surface and one was cracked through, but still in one piece. I will do some measurements when I refurbish the diff and determine if the thrust shims need to be reduced or eliminated.

Left side friction plates:

A7DE7636-194A-4154-B590-AD775D324CFF.thumb.jpeg.4f7469b0ee979ced31d6854294cfafc9.jpeg
 

Right side friction plates:

7E931019-DF7D-45D2-A2BC-A2B4D7A43FED.thumb.jpeg.1b571b113d0264c3ef3db1bdc6ec234d.jpeg
 

Cracked thrust Belleville washer:

BC133985-2D23-49CD-8230-FAC0C8D2F5CB.thumb.jpeg.f8844d68924ca9be95fed2cbcb61499a.jpeg

As my diff has been quiet and really predictable on the track with smooth locking and the condition of the diff besides the plates and thrust Bellevilles, I've just put in an order with Caterham for the £426 sintered plate rebuild kit (no VAT for my Canadian order). The Titan rebuild kit is about 2/3 the price, but doesn't include any shims, whereas the Caterham kit provides a whole set that will allow fine tuning of the clutch pack preload,

Link to comment
Share on other sites

I'd also check the pack movement before altering the shims, although shimming will alter the preload it also alters the travel and can put the Bellevilles in the wrong position - ie overloaded and working through more than their intended range of travel, which will lead to premature fracture.

Belleville have a massive range of springs in their range and are very helpful if your looking to change the spring whilst maintaining the pack height.

They took the dimensions from the old springs and ran a calc for me and emailed it over.

I removed the OE ones from my ZF which gave 70lb/ft preload and replaced with lighter ones, stacked 3 per side, whilst maintaining the pack height... and now have 14lb/ft of preload.

Link to comment
Share on other sites

  • Area Representative

Aerobod - I have 'permissions' to create a guide. Would you be OK with me attempting to transfer it to GUIDES 'Maintenance'?  Before I do you could add how to assemble & set up the LS unit/diff along with relevant torque loadings?

Once approved you can review & ask for amendments etc if required.

 

I suppose that leaving the support frame in situ was not possible the way the diff was dropped?

The diff internals are in pretty good nick considering the mileage & age. One in a million probably as every one else who suffered from the 'curse of the Titan' did not come off so well or cheaply.

As you state correctly when removing the A Frame, collect & make a note of the shimming washers from each forward end for re assembly. I did just that but could I reintroduce them all back in - NO!  It was as if the gap had shrunk by a couple of very thin washers. The A Frame alignment is correct after re measurement & alignement. There is no side play.  Strange.

 

 

Link to comment
Share on other sites

Hi Geoff, that would be great if you could transfer it to "Guides, Maintenance" once I have finished.

It will probably be a month or so until I do the reassembly, I just ordered the parts this weekend. I'm also planning to drill and tap a drain plug hole in the bottom of the casing, but will need to make a jig to hold the casing on my rather undersized bench-top combo lathe/milling head, to mill a flat spot before drilling and taping the hole. I've also ordered an M12x1.75 magnetic drain plug.

A couple of my thin shims are damaged from being caught by the thread of the long bolt, so I will measure the clearance of the support frame to the chassis when reinstalling and machine custom shims for each side. I have found there is too much flex of the support frame to the diff when bolting up, so prefer to get it fully installed and "flexed" as a unit to ensure the frame to chassis dimensions are stable, before shimming and centralising in the chassis.

One of the challenges is going to be holding the LSD and crown wheel when checking the torque, but I think I have a method of suspending it under the car without the casing so that I can insert the driveshafts to check the breakaway torque without putting the whole diff back together, while I play around with the clutch pack shims. Using a longitudinal length of wood with a couple of vertical blocks to support and  "trap" the LSD to keep it in position with the driveshafts straight, is what I think will work.

I think I was lucky with the diff wear, probably the case that the early carbon plates were more durable, seems to be sometime after the 2012 car that I have that they changed the composition to the most troublesome carbon plates before changing again to the sintered plates. Although two of the plates are worn out, the clutch pack Belleville washers don't look as though they would be over flexed with the other two plates close to original thickness, hence no fracturing in my case.

Link to comment
Share on other sites

James, have you considered putting the drain hole in the back plate? There's space below the filler plug and it might be easier to hold, machine and tap the back plate than the main casing. It's also only a £150 part you're machining, just in case!

BTW, what is that 'notch' in the top of your back plate? I haven't seen that before. 

Link to comment
Share on other sites

Hi Peter, I was initially going to drill and tap the backplate, but any low position to get the most oil to drain is in a thin area of the backplate, as it is significantly relieved on the inside. I would only be left with about 5mm of wall thickness after machining a flat on the outside to seal against, which isn't enough without welding in a boss, which could be iffy without knowing the exact alloy that the backplate is made from to use the right welding wire. The machined area below the fill plug is too narrow to get an M12 or even M10 bolt with crush washer to seal against and the last bit of the casing slopes in a lot as it meets the flange, so even with a boss welded in I could probably only drain 80% of the oil as the drain hole would need to be about 15mm above the bottom of the casing. You can see the back of the backplate in the photos in my original post, the bottom of the backplate is on the right in the photo.

In the end the casing is 20mm thick in the area I will put a flat and drill and tap a hole, between the bottom two back plate attachment holes. The casing is easily obtainable from any scrap yard from BMWs that have used the 168 diff over the past 20 or more years, in the slight possibility of some form of disaster while machining.

The notch in the top of the backplate on my car is to allow clearance around the fuel line, this is due to the fact that my car had the old style carrier and a different backplate originally that had clearance above it for the fuel pipe, but there was a recall on that backplate to replace with the new style due to interference with the deDion tube under high suspension loads. I decided to notch the backplate where there is plenty of spare material, instead of having to redo the fuel feed, which currently passes through a grommet in the steel angle bracket under the middle of the boot floor.

Link to comment
Share on other sites

My rebuild kit arrived today, not bad, as it was only shipped yesterday from Caterham and it had over 7.000km to travel in it's delivery.

A few differences besides sintered vs carbon plates:

- No Belleville thrust springs for the side gears, instead a thicker static thrust washer.

- Side gear thrust washers are now flat instead of recessed on the side that faces the gear and steel instead of aluminium.

- Thinner shims for behind the side gear thrust washers (I will have to measure to see if they are needed).

- Plenty of shims that will allow 0.1mm increments on each side of the clutch pack from 0.3mm to 1.8mm with either one or two shims either side.

Link to comment
Share on other sites

I added a drain plug in the lowest part of the casing today, Most of the work was getting the diff clamped down in a firm enough manner and ensuring both the internal and external pinion seals and bearings and any passages and blind threads were well covered to protect them from swarf.

I used an M12x1.75 magnetic plug that is normally a GM fit on a whole raft of vehicles, so is commonly available, it is from a company called Dorman, who produce decent quality aftermarket parts:

CB54EF38-0B24-4F7A-B59C-30AB510B8F1A.thumb.jpeg.10f0efe3b22fce98bf85b51608676397.jpeg
 

As I didn't clamp the diff down really rigidly (I would have had to make a jig), I didn't want to use a mill cutter on my general purpose bench top lathe / mill / drill press, so I just used a grinding wheel instead. I think anyone with a drill press where you can lock the height of the chuck would be able to use a similar technique to grind a flat spot by taking off about a quarter of a millimetre at a time. I moved the table with the diff clamped to it while keeping the drill head in the same spot:

9D6795DE-D6C9-4BFC-9004-B8A07FF71203.thumb.jpeg.b8a6bc3147fc465fc4b836194da1b83d.jpeg
 

I picked the thick part of the casing between the two lower holes that retain the cover. I was also looking at putting it further back, but any suitable relatively flat areas near the bottom are a bit close to the crown wheel and the casing would only be about 8mm thick after machining a flat, which is a bit thin for an M12x1.75 thread. After machining the flat, I drilled a 10.8mm hole (after centre drilling and pilot drilling 6mm first), then tapped it:

A1A96EE1-D81E-40B4-8273-3193E1070FB6.thumb.jpeg.85f482642f70b46f6d1f145db24643d5.jpeg
 

The drain plug I used has an integral rubber seal, but a crush washer would work, too. I torqued it to 30Nm, which is a common torque used by GM for this plug on a lot of cars:

FA9C05B8-44AE-499A-A278-CA7CE9644B8A.thumb.jpeg.a604ece01a35ccd1941f062cfae14e30.jpeg
 

The thread is exactly the right length for the casing thickness, leaving just the magnet protruding through the casing at the lowest point:

6200AC8D-575A-42DF-8AFB-829462F19E6E.thumb.jpeg.dfbb790012f4adab08d04fdb09651b4b.jpeg

Link to comment
Share on other sites

Today I did the LSD rebuild and re-install in the housing.

I took a few measurements of the new component thickness:

Belleville washers - 3.80mm uncompressed, 2.00mm fully compressed (material thickness, I didn't want to risk damaging them by compressing to 100%). Effective thickness as described below is 3.40mm, (x2 = 6.8mm).

Sintered friction plates - 2.08mm (x4 = 8.32mm)

Steel clutch plates - 2.00mm (x4 = 8.00mm)

Ramp "cups" with gears installed from face-to-face of the clutch surface on both cups - 56.00mm

Side gear thrust washer with backing shim - 3.50mm

LSD casing internal length at the maximum diameter - 79.00mm

LSD casing internal length between thrust washer recesses - 95.00mm

Minimum length between side gear thrust surfaces, end-to-end - 86.50mm

Side gear end float - 0.75mm each, 1.50mm total (no Belleville thrust washers, as these have been removed from the rebuild kit with thicker thrust washers instead).

The Belleville washers also sit within a "domed", "dished" or chamfered relief area in the casing ends, leading to a 0.4mm reduction in their effective height to 3.4mm, as can be seen in the highlighted area here:

DSCN0050.thumb.JPG.52b9f93332e55ccdaae5e7b5e3c7777a.JPG

I decided to start with 0.5mm shims either end (the shims used with the carbon plates were 0.45mm), leading to a total uncompressed pack length of (6.80 + 8.32 + 8.00 + 56.00 + 1.00) = 80.12mm. From some bench testing I did in measuring the compression of the Bellevelle washers, assuming a coefficient of friction of 0.2 in the bolt I used to compress the washer between two blocks, I came up with a spring rate of 3,800N per mm. This would mean that in compressing the pack 1.12mm, I would have a clamping pre-load force of about 2,130N (due to 2 spring washers in series having half the spring rate of the single washer).

Here is the set of components ready to assemble into the casing:

DSCN0051.thumb.JPG.4e2df1c5aa7bfcd605e40a5d5c5169d2.JPG

The thrust shim followed by the thrust washer with the 4 oil grooves facing out is first inserted into the casing recess:

DSCN0052.thumb.JPG.9a2a3224d4dd046f0acb0acb0d087606.JPG

Then a Belleville washer, clutch pack shim, clutch plate, friction plate, another clutch plate, another friction plate and the first ramp cup. Ensure the acceleration ramp, 30 degrees in my case, faces in the opposite direction to the forward rotation direction, if not swap the cups. My cups were marked "L/H" and "R/H", but when looking from the back of the car, L/H is on the right side, R/H is on the left side, so the marking doesn't seem to correlate to the side of the car. The side gear is them inserted through the pack. Ensure every component is liberally coated with your diff oil of choice as they are inserted:

DSCN0053.thumb.JPG.5f663aa69c3c83db53df5ccbb5768010.JPG

The spider gears and cross shafts are then placed in the appropriate ramp positions (30/90 or 45/60), followed by the other side gear. Look through the holes in the casing to ensure that you place the other cup's ramps to match the one already in place, it will only align properly in one position of the 6 available:

DSCN0054.thumb.JPG.3b5ecda0bd1d832428cec7405ffa93b4.JPG

Next repeat the friction disc, clutch plate, another friction disc, another clutch plate and then the shim followed by the Belleville washer. The thrust shim and thrust washer with the 4 oil grooves facing out are placed in the casing cap and should stay in place when turned upside down, with the right amount of oil on them:

DSCN0055.thumb.JPG.965eb93b0a6f0a0206f7814357a31c5c.JPG

The cap is then placed on the casing with the dots on each aligning:

DSCN0056.thumb.JPG.90d37b1d2abe28b3ff415596794b3d00.JPG

Next, using the old bolts (the new ones will be used on final assembly after checking the preload), hand tighten in a triangular sequence until all slack is removed, then tighten a half turn at a time in the same pattern with a torque wrench until they are all tight at 40Nm.

DSCN0057.thumb.JPG.d6cd40e1e4005db4090d79c118620f5c.JPG

Check the ramps are in the right direction, you can see the 30 degree acceleration ramp here, facing down when viewed from the back of the diff, the back of the crown wheel will move up when going forward:

DSCN0058.thumb.JPG.d9e44ec7c6e9aa6dd055fbe32788681e.JPGI didn't manage to finish the install back in the car, as I found my RTV sealant had gone off, so will have to go to the shops to get some more before sealing the back cover on. I also didn't manage to find any new Nyloc nuts for the 1/2" bolts, although I did manage to get all the replacement metric ones.

The next bit will vary depending on how you removed the diff from the car. The aim is to have the LSD supported using wood or suitable material while inserted onto the driveshafts. I ensured by inserting wood under the LSD that it could not fall, then packed more around it to prevent it moving fore and aft. It does need to rotate, though, so avoid the teeth digging into the wood supporting it. Next apply an increasing torque on one axle (by using a torque wrench and socket on the end of the axle nut and rotating in a forward direction) while the other is restrained by stopping the wheel from rotating. Initially mine broke free at 65Nm, then settled at 55Nm with repeated clicks of the torque wrench, which correlates to 40.6lbft, about as close as I'm going to get to 40lbft preload.

I was lucky, guessing the right shim first time, in the current configuration the preload I have has the Belleville washers at 30% deflection (0.56mm of 1.80mm at 100% deflection).

If the preload is too high or low, remove the LSD, disassemble and swap shims as necessary:

DSCN0059.thumb.JPG.97348a92a0243ff016faad9072dcfefa.JPG

Next, to disassemble if you need to swap shims, take out the 6 bolts, then use 3 of them in the threaded holes in the cap to lift it off by tightening each gradually until it frees from it's slight interference fit. I cleaned the threaded holes out and used blue thread lock to put the new bolts in, before torquing in sequence to 40Nm:

DSCN0060.thumb.JPG.4ecd0aa00db9ecff2c45029e9897e1d2.JPG

Once the preload is set, re-insert the LSD and crown wheel into the casing and slide the liberally oiled bearings in. Ensure the correct circlip is used on each side, based on your markings and/or recording of the circlip thickness from disassembly. The clip on the first side will generally completely expand into the slot, but the second one may need some tapping with a mallet and piece of soft metal such as aluminium or brass. ensure it is fully expanded and in the groove with the opening either side of the channel at the top:

DSCN0061.thumb.JPG.079823a7fc6193d0cc67e77e8cf67677.JPG

The new seals should only be inserted until flush with the casing. Use a flat block to work around until the seal and machined surface are flush

DSCN0062.thumb.JPG.9e5cc6ed8a46f36a9711b4bb00a27cf4.JPG

The LSD is now fully installed in the casing:

DSCN0063.thumb.JPG.614d01d48b5d53b791754c1d1555be58.JPG

Caterham calls for a 5mm bead of RTV sealant on the casing face to seal the cover. I used Permatex Ultra Gasket Maker:

shopping_0.thumb.jpg.a6aba6b1b379f10ef3ca6ca574144a28.jpg

Although each sealant will vary in the application instructions, this one says to apply a bead ensuring all bolt holes have a bead around the diameter, not just on one side. The bolts are then done up finger tight only until a bead of sealant is visible squeezed all around the periphery:

DSCN0066.thumb.JPG.0a73b9e9a132d28510efcd48d113e47c.JPG

After one hour the 7 cover bolts are all torqued to spec - 48Nm. After leaving 24 hours to fully cure, 0.8 litres of diff oil is then added (Caterham says it should not reach the fill hole). I'm using Red Line 75w140 GL5 fully synthetic gear oil which already contains the appropriate friction modifiers for plate-type LSDs.

Link to comment
Share on other sites

That's a great read, but what is now puzzling me is the difference between the Sierra and BMW. The Sierra one has no shims - it did have the correct pre-load when I put it together, but no adjustment if it didn't. You also mention that the Belleville sits in a 'dome', but the Sierra one is flat. 

It could be that the design has evolved (mine was one of the first) or the Carbon plate update required a more adjustable design. Perhaps it could be that the BMW diff just needs to be a different size and shape. How do you set the crown wheel position (backlash) on the BMW? 

I have a later Sierra one to do in the coming months so perhaps that will help answer some questions.

Link to comment
Share on other sites

Hi David,

The shims aren't necessary if the preload reaches spec without any added. As Titan spec the preload on the "medium" LSD at 20 to 80 lbft, shims may only be necessary for the higher preloads. The "dome", "dish" or chamfered relief is quite subtle, I didn't initially notice it until I put a straight edge across the cap. It may have also been a running change. It allows the Belleville to centre and also potentially not reach 100% compression, as the inner diameter is 0.4mm deeper than the outer diameter in the casing and it's cap. If the ends of the casing were flat, then 0.4mm of shim could be removed from each end to give the same prefload if all other dimensions are the same. I believe this 0.4mm chamfered relief that the Belleville washer sits in will limit the washer to about 80% of deflection (3.8mm height of washer and 2mm material thickness, reduced to 2.4mm height when compressed against the chamfered relief).

The BMW backlash and the side bearing preload is set by the thickness of the side circlips that sit in an accurately machined groove about 5mm wide. I've seen them online in 0.02mm increments in the 3 to 4mm range, mine are marked 3.44mm for the left and 3.62 mm for the right. The pinion postition is set by a special crush washer if the bearings have to be changed or the pinion removed for any reason, before the crown wheel mesh and backlash is adjusted.

I measured my backlash at 0.14mm. I don't know what the exact spec is, but various BMW diffs are in the range of 0.05 to 0.2mm, so I think mine is fine:

DSCN0064.thumb.JPG.facd5770f7df1412ac2bb5d5de9d1ca6.JPG

 

Link to comment
Share on other sites

I had the time to put the diff back in today, having left the RTV to cure for several days before filling it with oil. Due to the location of the filler, I prefer to fill it on the bench before lifting it into position. In terms of reassembly, I used the following torques on the components:

Fill plug - 40Nm

Carrier to diff casing M12 Allen bolts  - 110Nm with Schnorr washers and blue thread locker (Caterham specify 87Nm, but they are 12.9 bolts with a good thread depth that can take a higher torque and I have lost 2 on track before).

Carrier to diff cover M10 long bolt - 48Nm with new Nyloc nut and plain washers each end.

Carrier to chassis M12 Allen bolts - 87Nm with Schnorr washers (Caterham specify 60Nm, but I've had these bolts loosen before)

Carrier to chassis 1/2" UNF long bolt - 60Nm with the low profile serrated washers that should have been on each end of the bolt.

Hub and ear to deDion tube M10 bolts - 48Nm with new Nyloc nuts

Diff to propshaft M8 Allen bolts - 74Nm with blue thread locker.

Anti roll bar brackets M6 bolts - 14Nm with new Nyloc nuts

Brake caliper slider bolts M8 - 30Nm

A-Frame M12 and 1/2" UNF bolts - 81Nm with new Nyloc nuts

The assembly procedure is a reverse of the disassembly, but there are a few things to watch out for. First is to ensure the carrier is properly shimmed in the chassis bushes. My shims were rather beaten up so I measured the shims required to centre the diff squarely in the chassis (ensuring the drive flange is in the centre of the tunnel and the diff is square to the chassis). I needed 2.25mm shims on both lower bolts and a 2.5mm shim on the left of the top bolt, 3.5mm shim on the right of the top bolt. I measured the shim to just slide in under hand pressure, but not fall out when pushing the bolts through them.

The beaten up shims in the top of the photo, a nice custom one in the bottom:

DSCN0070_0.thumb.jpg.6dd6525d7a02f06f02c2ba4a76d5be58.jpg

I actually machined the shims from an old A-Frame bush that I had kept, the core had stripped out, so I just sanded off the remaining rubber, then sliced off 4 shims of the right thickness (measured with the diff in place using feeler gauges):

DSCN0069.thumb.jpg.96aaa34c7532382c11d17327e5f80adc.jpg

With everything square and properly shimmed, I found the long top bolt when covered liberally with copper slip only needed a few gentle taps from the mallet to be driven through.

Another thing to watch out for is using the correct number of washers on each side of the A-Frame to ensure the deDion is central in the chassis. Using a combination of normal washers at 2.5mm thick and fender washers at 1.5mm thick (I used ones similar to the normal washers in overall diameter and drilled them out to 13mm). you should be able to get the deDion within 0.5mm of absolute centre (up to 1mm different side-to-side).

Make sure when the diff is raised into place that the brake cables are not trapped above the carrier top mount:

DSCN0068.thumb.jpg.0abe8b44ab546a14b4c76d0c2a27337f.jpg

To tighten up the propshaft bolts I ensured the brake cables and caliper were back in place and adjusted, so that the handbrake was functional again to hold the driveshafts and stop the propshaft rotating. Ensure that the propshaft and diff flange line up with the same hole positions as when removed. I have a paint mark on mine to line them up.

Finally, all back together and ready for next season!

DSCN0072.thumb.JPG.4177d6ab1e7d6105b8e7b165ad4ea909.JPG

 


 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...