Shock Absorbers and Diff(?) - Quote Shock

Thanks again to everyone for the advice. I’ve been slowly working away, mainly on weekends, and finally finished all the jobs. Except that I’ve now decided to replace the steering rack boots and got held up on that as described in another thread. It went fairly well, and I needn’t have been so scared of the jobs. Actually the task that I got really hung up on was replacing the front lower shock absorber bushings, but half of the trouble there was getting off a cross-threaded lower nut.

The new diff output shaft bearing fixed the noise from the back, so that’s the main issue sorted.

The suggestions for parts sources were useful for comparison, but in the end I found Berkshire Jag Components in the UK, who had good pricing and everything in stock. They carry parts for the XJ40 and later models. The quality seems good and everything came correct and well packaged. Took two weeks to send and get to Australia.

Prestige Spares in Melbourne indeed seem to have closed down (phone and email both dead), probably at the same time as an associated mechanic on the same street earlier this year. It turns out I bought some of their left-over stock a while ago (a bulk lot of XJ40 relays) and didn’t even realise! They were also my sole source for used parts in case I really stuffed something up, so quite a shame.

The rest of this post is sharing my own notes from the jobs. I try to keep notes for all the jobs I do, so this time I thought I’d share them for anyone else doing the same. But feel free to ignore the rest.

Vehicle: 1990 model (built in 1989) 4L Jaguar XJ40, RHD/Australia

New parts required

Jurid coupling replacement

Propshaft jurid coupling (CBC8996) x1

Rear shock absorber replacement

Rear Shock Absorber (CBC5958 / CCC3538 / CCC6923) (including bushings and rubber boot) x2
Rear shock Absorber Spring Isolator (MMD3565AA) x2
Rear shock Absorber Guide Bush (CBC2933) x2
Nyloc nut for lower bolt: M16 x 2.0 DIN 985 (NY116041) x2

Front shock absorber upper and lower bushing replacement

Front shock absorber upper isolator (rubber) (MMD2144AA) x4
Front shock absorber damper bush (CAC75851) x2
Nyloc nut for lower bolt: 7/16" UNF (NY607041J) x2
Nyloc nut for upper shaft: M10 x 1.0 CL8 (NY606041J) x2

Diff Output Shaft Bearing replacement

Diff Output Shaft oil seal (JLM618) x1
Diff Output Shaft O-Ring (JLM621) x1
Diff Output Shaft Bearing (JLM617 / JLM11527) x1
Diff Output Shaft Bearing retainer collar (JLM615) x1


Jurid coupling replacement

  • Went fine except that it took a lot of force to lever the driveshaft back, and then pulling it back again was awkward too because the centre bearing needed to fit back into its hard-to-access housing.

Passenger side diff output shaft bearing

  • driver side bearing replaced a few years ago by mechanic

  • Taking out the shock absorber strut first (for shocker replacement later) allowed for a lot more room to work in. Job went slow but steady - remember five bolts on the driveshaft flange, not four!

  • There was a spacer plate on this side between the driveshaft and the output flange, it fits into a notched steel cover that appears to be used for reading rotation speed with a magnetic sensor - for the speedometer? There isn’t one on the driver’s side.

  • Replacing the bearing on the shaft went fine following the Don B guide. The old bearing was clearly worn out, with lots of pitting/chips on the bearing surfaces, and turned rough when spun. It had been replaced before, unknown make (made in Korea), not an SKF part like the replacement. The new one went on without incident, and I didn’t leave behind nearly as much ‘evidence’ on the shaft as whoever did it last.

  • Lots of blue RTV sealant goo on the driveshaft flange and diff, which was a slow and tedious job to scrape off. I decided not to apply that during re-assembly. Hopefully it doesn’t leak.

  • Fitting everything back together went without issue. A wobble extension was useful to access the nuts/bolts with my torque wrench.

Rear shock absorber replacement

  • I bought a set of spring compressors that claimed to have hardened steel threaded shafts. Spring “wire thickness” was 1mm wider than the maximum specified on the box, which made me nervous but they seemed to work fine.

  • Replacement shockers were Bilstein. Old ones were Sachs (as replaced by mechanic a few years ago). Both old shockers tested fine out of the vehicle, though driver’s side one was leaking and the boot was torn (hardened up from the oil), hence the replacement.

  • Top nut on the shocker was undone using my new 17mm ratcheting spanner and vise-grips to hold the notch on the shaft. This ended up bending the vise-grips and starting to round off the notch. A 1/4" spanner fits the notch quite well and is a much better option, combined with needle-nose pliers for the bit at the end where the nut is in the way of the second spanner.

  • The big ‘doughnut’, at least of the passenger side, doesn’t appear to have been replaced when I had the shockers replaced by the mechanic a few years ago.

  • Passenger side upper mounting plate for the strut, where the “cowboy hat” bushing fits in, had a serious notch worn into it by rubbing against the shocker shaft after the bushing had worn away. The shock absorber shaft itself has been worn away a bit there as well. A 1-1/4" washer was a similar thickness to the steel of the mounting plate and fit very well in the recess on the top. So this was fitted and a piece of the old bushing was cut out and sandwidched in the gap outside the new bushing. The driver’s side plate had a much smaller notch, and was given the same treatment. Superglue the sandwiched spacer bit to the ‘cowboy hat’ to avoid the incredible frustration of everything falling apart repeatedly during assembly and bouncing away on the floor!

  • Springs need to be compressed more for reassembly of the struts because the bushings aren’t all squashed. Orientate strut vertically in the vise so that the bushings can be centred when expanding the spring.

  • To reinstall strut, need to tighten top bolts first (needed to use a punch to lever the mounting plate into alignment with one bolt hole for the driver’s side). Then jack the arm/hub up to the best position possible and forcefully lever the end of the shocker in line with the lower bolt hole while trying to push/screw the bolt through. I kept thinking there must be an easier way to do this, but I’ve convinced myself that there isn’t unless you keep the springs compressed while putting the struts in so the arm can be jacked up to its ‘loaded’ position, and then it would be awkward to get the spring compressors out.

Front shock absorber upper and lower bushing replacement

  • Top most bushing (the one in the engine bay) on the passenger side was the most distorted and left a significant gap, as predicted in the Don B guide due to heat from the nearby coolant tank. That’s very likely the cause of the knocking sound from there. All bushings were replaced though on both sides, including lower bushings pressed into the lower suspension arm. The front shockers (Boge brand, not replaced while I’ve had the car) were tested and working perfectly, with no leaks.

  • Same ratcheting spanner and 1/4" spanner combo used for the slow job of undoing upper nuts. Access on the passenger side was difficult (ie. painful, for turning the spanner) even after removing all the surrounding air intake parts (which got a clean at the same time).

  • The lower bolt on the driver’s side was a nightmare. The nut fought incredibly hard all the way off the thread. Sockets put too much leverage on the bushing so it twisted and they slid off. The only option was to use a spanner on both ends, but my arms weren’t strong enough to turn it and the bushing absorbed blows from a hammer. I had to use my leg to turn it little bites the whole way. Unfortunately the strain from this hurt my knee rather badly. It turned out that the nut had been cross-threaded on the bolt (likely using a rattle gun) when the lower bushing or shocker was last replaced, which also damaged the bolt threads fairly badly, and I spent a couple of hours cleaning up them up. The passenger side lower bolt was easy as pie and came off using a socket, so I was just unlucky on the driver’s side.

  • Old lower bushings were URO brand. Only slight deformation/cracking at the bottom, but worth replacing to be sure and seeing as I’d got that far.

  • Replacing the lower bushings was a pain as well. Drilled out the rubber centre with a “rotary file” bit on one side, but the rubber kept slipping away from the bit and it took a long time. For the second time I used a small hole saw (one with a screw-on collar, not the wide sort that won’t fit), and that cut out the middle of the bushing much more easily. Then following forum instructions I threaded through a hacksaw to cut through most of the outer ring of the old bushing, then used one chisel to fold in an outer part of the ring, followed by a smaller one to hit against that and push the ring out of the hole. I did cut a little too far on the driver’s side and left a small notch at one end of the mounting hole.

  • To press the new one in at first I tried a G-clamp, but it kept slipping out of position and ended up bending up the end of the new bushing. Then I followed instructions on the forum and used a short length of 10mm all-thread and a socket (21mm is the size that I settled on in the end) to ‘screw it in’. That stripped out some 10mm nuts, but worked in the end. It was easier (though not easy) on the one that I hadn’t bent up, of course. I needed a wobble extension to fit the socket on around the steering knuckle.

  • Fitting the front shock absorbers back in was made easier by using cable ties to compress them until they were in position. The jack supporting the suspension arm was raised take the weight of the vehicle before tightening the upper shocker nut, as suggested on the forum.

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Just one question on the list, you did make sure the Jurid coupling was replaced in the correct orientation? That’s with the thicker area under compression when going forward.

Probably not. I did follow Haynes by marking the orientation on the old coupling, but I didn’t really know what that was supposed to match up against on the new one. It was the first job so I can’t remember what I guessed.

Sounds like I’d better get under there again and see. Which way does the diff input shaft spin going forwards?

You can see the thicker sections in the photo.

Same direction as the engine.

I checked it and it looks like I did get it right - the prop shaft pushes the diff shaft around via the thicker parts when turning clockwise (when viewed facing towards the diff). Thanks for pointing it out though, I’ll add it to my notes for next time.

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