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So I just took my beloved XJ8 for its MOT and it failed the garage advising: "Sub-frame corroded and seriously weakened nearside rear (2.4.G.1)". The guy who did the MOT had left by the time I got there, and the guy who I talked to could only tell me "You`ll need to replace the rear sub-frame, we don't do that here".
Can anyone advise how big of a job replacing the rear subframe can be? I can see second-hand subframes in the UK for around £150-200, assuming that's the only thing that needs replacing. Am I looking at a huge labour bill? I am gutted as now the MOT has run out and I can't drive her.
I'm not trying to discourage you, but I want you to be aware of what you may be in for by doing this yourself.
I've circled the main disassembly points which attach to the body. There are some clips and smaller connections that need to be undone and tied back. But as you see, this really isn't for the average weekend garage warrior unless you have experience and the correct equipment and space, because this is very heavy as you can probably tell by the girth of the assembly. You'll need space to roll it out from under the car and reinstall the new one. That is if you can get it up high enough for the work. Then what to do with the old one?....you'll need to dispose of it. A garage buddy is almost a must also.
I would definitely at minimum get some quotes for this from some garages and then save some effort and have the assembly sent directly to the garage you find to do it. A properly equipped garage should be able to do it in a day barring any unforeseen issues. Plus they'll get rid of your old assembly and you avoid a possible hernia.
Here is one cleaned up and ready for reassembly:
Last edited by Highhorse; Oct 1, 2016 at 08:23 PM.
Thanks for the info. No need to put me off doing it myself, I wouldn't even attempt this job due to the weight of the subframe. I was just wondering if anyone could advice how many man hours the job might be to figure how much in labour costs I'm looking at - there is only one Jaguar garage near me and they won't even give me a rough quote unless I take the car to them for an inspection (they are the only Jaguar dealership in Gloucestershire and aren't well recommended). I'll phone some more garages on Monday.
Hopefully someone like motorcarman or Tijoe whom I believe have quite a bit of experience will chime in. I have seen Tijoe referenced for rear sub frame questions by others. I don't know if you can PM him with you being somewhat new, but give it try or I can ask him to look at this for you or have him PM you.
Also, have you checked with your local Jaguar Club to see if they can assist? https://www.jaguarforums.com/forum/uk-eire-68/ ....since they are in country, they may be able to point a finger to a better unknown mechanic and cost savings. Can you update your location so other folks in your area who may see this (and future posts) may be able to help.
Last edited by Highhorse; Oct 2, 2016 at 05:57 AM.
You need to clarify which part of the subframe - it has a lower A frame stiffener and the front edge of this part gets salt blasted until it's got more holes than swiss cheese. At that point it's a fail. The picture was taken of a then 8 year old car with 140K.
Behold
If it's just this part then it's an couple of hours to fit and you'll get the pass. I would recommend renewing the outer bushes as they're usually damaged when the frame is removed and cannot be reused.
I've jacked the car up to have a look - it is indeed the A-frame that needs replacing, there's a disturbingly large hole in it made by the rust. Going by this guide, this actually looks like a straightforward job I might give a go myself:
I might try to find a Southern United States located part and have them ship it to you. It might actually be cheaper and from a completely rust free zone!
Any competent shop should be able to complete this repair. When you find good salvaged replacement parts, I would recommend replacing the large bushings that isolate the subframe from the body or differential gear noise may be transmitted into the passenger compartment (and steering precision also suffers).
As Sean mentioned, if it's only the lower horizontal A-frame that is rusted, it can be replaced without dropping the differential or any other components. If the vertical A-frame or "mounting bracket" at the front of the diff is also ruined, replacement may also be possible without dropping the independent rear suspension (IRS), but may be easiest if you do. It's not as difficult or time-consuming as you might think. Here are some photos showing the job on an XJ40, which is very similar to an X300 and X308. Sorry the large photos aren't currently working, but you can see the thumbnails and descriptions:
Update! Out with the old, in with the new (A FRAME baby!)
Originally Posted by Nicdilla
Now that's a rusty A-Frame! Swiss cheese.
Looks like a lot more was damaged that I thought. Replaced the top Pillar and the support bars. Should be a much better ride when I'm done. I figure I will have exchanged the diff fluid before I'm done and swap out the seal. Oming along fine now that the parts are coming through. Not to hard find either.
You need to clarify which part of the subframe - it has a lower A frame stiffener and the front edge of this part gets salt blasted until it's got more holes than swiss cheese. At that point it's a fail. The picture was taken of a then 8 year old car with 140K.
Behold
If it's just this part then it's an couple of hours to fit and you'll get the pass. I would recommend renewing the outer bushes as they're usually damaged when the frame is removed and cannot be reused.
@Highhorse that isn't an X308 rear end.
I just redid the bushings on my A-frame. Fortunately, rust not even close to what OP has. I did wire brush it down and repainted with Eastwood Chassis Black primer and paint. I also brushed some epoxy filler (aka JB weld) along that edge that takes the brunt of road debris, etc., then painted over that.
Oops, looking at these pics just reminded me that I did not put the connecting pipe between the two charcoal canisters back on. Bead blasted and painted that just for good measure. (the a-frame is too big for my blast cabinet, else might have done that as well).
Corroded rear subframe
the garage advising: "Sub-frame corroded and seriously weakened nearside rear (2.4.G.1)". The guy who did the MOT had left by the time I got there, and the guy who I talked to could only tell me "You`ll need to replace the rear sub-frame, we don't do that here".
.
Update! Out with the old, in with the new (A FRAME baby!)
Bead blasted and painted that just for good measure. (the a-frame is too big for my blast cabinet, else might have done that as well).
