Recent Threads
Yeah the OE BMW install has a funk PCV system which attaches into the intake ahead of the filter, but that's all gone now that I've changed the cam cover (will be coming in a later update!).
Was planning on a catch tank so hopefully that'll be enough, and will help avoid any nasty runaway situations!
Don't let the next update derail the conversation though
20th June 2020
Next couple of steps on the Jag. Got the engine bay rust wire wheeled, treated and primed.
By and large this isn't a particularly rusty car, but it's amazing how many little bubbles there are where paint's been chipped away or not covered for whatever reason.
That was yesterday, and managed to get the basecoat on today.
I've been using my airbrush which is brilliant for little touchup jobs, but I'm not sure it's quite cut out for this scale of job. The poor motor was getting quite hot by the end of each coat. I'm also not convinced it will give a nice even fade, even with some blending out, thanks to the mica paint the Jag has. Not that it's overly bothering me as this'll be a daily driver and the engine bay's bound to get mucky.
Still, good for making sure unseen bits don't rust.
21st June 2020
Aand the paint's done. Lots of learning on this one, but luckily it'll be hidden by diesel engine bay dirt :S needs more colour coats than I did with 1k base to cover the colour of the primer. Really with an airbrush it needs blending into the paint underneath, which again would be easier with straight 2k rather than clear over base. Still, it's hopefully stopped most of the rust from progressing and that's the main thing.
I still have the bulkhead panel to fix so the engine can't go in yet, but I thought I'd have a look at brakes. In stock form, the brakes on an XJ40 are very good. Thanks to the hydraulic gubbins in the previous posts you get a lot of braking force to stop the car without having a squishy pedal. Their only real issue is that they tend to fade under hard use, so a bigger disc for better heat capacity would be useful.
As standard, the later 40s like mine have a 291mm disc at the front. People have fitted the 298mm front discs and twin-pot calipers from early XJ81 V12s (the V12 version of the XJ40), but parts are getting a bit thin on the ground these days. There are also megabuck 4-pot caliper/massive disc solutions which the racers tend to go for.
I then got looking into later versions of the '40 chassis. X300s have bigger rears (and vented) but the same fronts. X308s have the same, but the XJR8 has beefy 325mm fronts and 326mm rears. The fronts even use the same standard calipers as an XJ40. Bingo!
Rears will come later, but I bought discs and caliper carriers for the front. They're noticeably bigger, and thicker too (1mm thicker, but also less venting space).
Couple of issues though. Turns out Jag changed the hubs and vertical links for the X308. There's a little step on the XJ40 hub that locates the disc which isn't present on the X308, so the centre-bore of the discs will need boring out.
Also, the new discs have a smaller hat so the disc sits physically further forward on the V8 car. Turns out they did this by changing the mounting lugs on the vertical link, not the caliper carrier. Did some measuring and found that I'd need a 16.5mm spacer to get the disc central. Luckily, I've been hoarding little bits of metal that look useful for years so I had a piece of box section that was 16.4mm in diameter.
Some further testing showed you need to take a sliver off the hub-side of the carrier to clear the metal dust/heat shield. Couple of mm at an angle should do.
With that I could get everything mounted in place to check it clears on my wheels (Japan Racing JR9s, 17x7.5 ET20). It's less the OD that's the issue, but the space between the caliper and the face of the wheel. Luckily, it does!
I can say they definitely don't clear the stock 15" wheels (caliper hits the outside), but I don't have any 16" ones around to test. If they do it'll be a close run thing.
Oh, and if anyone wants dimensions for the spacer here they are (as yet untested, but will see how they work):
I was originally looking at getting one machined, but it turns out you can quite readily get 30x16 bright steel bar stock so I've ordered some of that and will have a go at making my own (there's 2.5mm of clearance either side of the disc so there's a bit of leeway). There's a chance it might turn out to be 5/8" (15.875mm), which should still work and can always shim it out slightly if it doesn't
Also, as a recent update, I haven't yet found anyone who's willing to take the bore out on my brake discs. It should be a simple job, but needs someone who's got a sodding great lathe as the OD of the discs is 325mm! If anyone knows anyone who has a large lathe who would be up for a quick job for a bit of cash please let me know!
Was planning on a catch tank so hopefully that'll be enough, and will help avoid any nasty runaway situations!
Don't let the next update derail the conversation though
20th June 2020
Next couple of steps on the Jag. Got the engine bay rust wire wheeled, treated and primed.
By and large this isn't a particularly rusty car, but it's amazing how many little bubbles there are where paint's been chipped away or not covered for whatever reason.
That was yesterday, and managed to get the basecoat on today.
I've been using my airbrush which is brilliant for little touchup jobs, but I'm not sure it's quite cut out for this scale of job. The poor motor was getting quite hot by the end of each coat. I'm also not convinced it will give a nice even fade, even with some blending out, thanks to the mica paint the Jag has. Not that it's overly bothering me as this'll be a daily driver and the engine bay's bound to get mucky.
Still, good for making sure unseen bits don't rust.
21st June 2020
Aand the paint's done. Lots of learning on this one, but luckily it'll be hidden by diesel engine bay dirt :S needs more colour coats than I did with 1k base to cover the colour of the primer. Really with an airbrush it needs blending into the paint underneath, which again would be easier with straight 2k rather than clear over base. Still, it's hopefully stopped most of the rust from progressing and that's the main thing.
I still have the bulkhead panel to fix so the engine can't go in yet, but I thought I'd have a look at brakes. In stock form, the brakes on an XJ40 are very good. Thanks to the hydraulic gubbins in the previous posts you get a lot of braking force to stop the car without having a squishy pedal. Their only real issue is that they tend to fade under hard use, so a bigger disc for better heat capacity would be useful.
As standard, the later 40s like mine have a 291mm disc at the front. People have fitted the 298mm front discs and twin-pot calipers from early XJ81 V12s (the V12 version of the XJ40), but parts are getting a bit thin on the ground these days. There are also megabuck 4-pot caliper/massive disc solutions which the racers tend to go for.
I then got looking into later versions of the '40 chassis. X300s have bigger rears (and vented) but the same fronts. X308s have the same, but the XJR8 has beefy 325mm fronts and 326mm rears. The fronts even use the same standard calipers as an XJ40. Bingo!
Rears will come later, but I bought discs and caliper carriers for the front. They're noticeably bigger, and thicker too (1mm thicker, but also less venting space).
Couple of issues though. Turns out Jag changed the hubs and vertical links for the X308. There's a little step on the XJ40 hub that locates the disc which isn't present on the X308, so the centre-bore of the discs will need boring out.
Also, the new discs have a smaller hat so the disc sits physically further forward on the V8 car. Turns out they did this by changing the mounting lugs on the vertical link, not the caliper carrier. Did some measuring and found that I'd need a 16.5mm spacer to get the disc central. Luckily, I've been hoarding little bits of metal that look useful for years so I had a piece of box section that was 16.4mm in diameter.
Some further testing showed you need to take a sliver off the hub-side of the carrier to clear the metal dust/heat shield. Couple of mm at an angle should do.
With that I could get everything mounted in place to check it clears on my wheels (Japan Racing JR9s, 17x7.5 ET20). It's less the OD that's the issue, but the space between the caliper and the face of the wheel. Luckily, it does!
I can say they definitely don't clear the stock 15" wheels (caliper hits the outside), but I don't have any 16" ones around to test. If they do it'll be a close run thing.
Oh, and if anyone wants dimensions for the spacer here they are (as yet untested, but will see how they work):
I was originally looking at getting one machined, but it turns out you can quite readily get 30x16 bright steel bar stock so I've ordered some of that and will have a go at making my own (there's 2.5mm of clearance either side of the disc so there's a bit of leeway). There's a chance it might turn out to be 5/8" (15.875mm), which should still work and can always shim it out slightly if it doesn't
Also, as a recent update, I haven't yet found anyone who's willing to take the bore out on my brake discs. It should be a simple job, but needs someone who's got a sodding great lathe as the OD of the discs is 325mm! If anyone knows anyone who has a large lathe who would be up for a quick job for a bit of cash please let me know!
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