Ever since I bought my X300 ive noticed that it's a bit unsettled over bumps. I never thought much of it but the other day I had the right front wheel off and I noticed that the front subframe is cracked badly around the upper control arm/wishbone.

Obviously I need to fix this so I was wondering what can be done;

1 - replace subframe with a good used one, but how can I ensure that this doesn't happen again?, what causes this problem initially?

2 - is it possible to repair the original subframe?, remove it and weld reinforcements on/patch the crack.

3 - how do I remove the subframe?, from what I can think of it would just be supporting the engine, unbolting the engine mounts, brake calipers, steering shaft etc. If anyone could direct me to a guide or more information I would appreciate it.

If you've got any ideas, warnings, opinions or answers to the above please let me know.

 

a good frame shop should be able to weld it adequately without removing it. But, then it's to rack to see if it's all straight. I would consider a replacement crossmember.

If it's been cracked for some time, it's most likely stretched out of shape, which will throw your front-end tracking/alignment out.

There's enough rusted hulks around that you should be able to get a complete unit for a reasonable price. Rebuilds it on the workbench, then pick a weekend for the swap.

 

I had my subframe off for repainting and to assist in the replacement of all the bushes.

We hung the engine from a bar across the wings then put a jacking beam under the subframe. Remove the shocks, springs (you really need to use a Jaguar spring compressor because if they let go, they'll punch a hole through concrete). Remove the rear fulcrum bolt - helpfully, Jaguar had cross-threaded mine in the factory. Down the whole lot comes.

SPX sell the spring compressors for a reasonable price (not far off the price of borrowing one twice from the JEC).

 

It's over twelve years since I had my X300 and engine support cradles weren't readily available in the UK then so I improvised!



However you chose to support the weight of the engine (from above) and the transmission (from below), safety is critical. These are heavy components.

This is the sequence I followed to remove the Cross Member:

• slacken rear cross member mounting bolts - 28 mm hexagon with nyloc
• remove air intake & MAF sensor to access LH cross member bolts
• slacken shock absorber and front Vee mounting bolts (2 per side on Vee mountings) 17mm shocker top & 10mm Vee mount
• support car body on axle stands under front jacking points
• remove front wheels
• remove front brake calipers from carriers & hang on wires from cross member mounting (tie-down?) brackets
• disconnect speed sensors from brake carriers & hang next to calipers
• disconnect track rod ends
• disconnect & remove speed sensor wiring harness (2 cable ties – top and front of cross member)
• disconnect steering rack pipe clips but leave pipes connected
• disconnect steering rack pinch bolt
• disconnect steering rack from cross member – 4 nuts & bolts and separate from steering shaft
• support steering rack on suitable block of wood and move it as far back towards gearbox bellhousing as possible
• support engine from scaffolding - roped through brackets and around manifolds
• support front of cross member – timber again to spread load
• remove front bumper cover undertray
• remove 2 rear cross member mounting bolts
• remove 4 top Vee mounting bolts
• lower cross member on trolley jack and slide out from under car (had to compress shock absorbers to clear front bumper cover - should have removed them
• remove & replace Vee mounts – T40 torx bit

I went further than this because I was replacing a leaking engine sump but these are the steps to get the cross member off.

Graham

 

Thanks for the replies. It doesn't seem as difficult as I initially thought, just need to be safety conscious. The other thing I was wondering is if I get a good used subframe is there anything I can do to it to reinforce it?