They are self aligning and threading bolts. Just replace them with standard bolts the same size.
Several of these in 5/16 size secure the transmission crossmember.
I assume they somehow prevent loosening, kinda important bolts? If I go with standard threads, do I need loctite?
I suspect they are just faster/less prone to cross thread when rapid assembly/ air tools are involved. I would not loctite, personally.
Hmmmm, interesting. Special bolts for quick assembly, but me being super slow and careful, not needed. Thanks!
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Why not just clean them up and chase the threads, they’ll be good as new.
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Good enough for the factory? Good enough to reuse.
I couldn’t live without a tap & die set 
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as I started gathering the parts to prepare the same job, I’ve seen those in the parts lists, and discovered that each side has a different part number, and one of them is not available anymore
edit : LH is the one to save : see
https://parts.jaguarlandroverclassic.com/parts/index/part/id/C03.910.91057.91057274.910572744786/brand/jaguar/
Heatshield
RH — — —[C45367] £4.34 inc VAT
LH — — – [C45368] No Longer Available|
as suggested by Bob, they’re useful when you need to (re) fit the assembly : you need to align several bolts/holes at the same time
starting with those helps to get the alignment with 2 un-threaded bits, then tighten them and add the other bolts
using standard bolt will work fine, but will need to be more careful not to cross thread one of the fixings
I guess the heat shields work! My vee mounts are probably original, and although dirty, seem to be ok. They sit right next to downpipes.
I made sure to buy oem replacements. Expensive, but archives relate anything aftermarket to be avoided.
I also find it interesting that something as heavy and important as subframe is bolted up on the rear vee mounts with such wimpy bolts and nuts (3/8"). Whereas the front bushings need massive 3/4" bolts and nuts. I don’t understand the engineering, but somehow front mounts do most of the work?
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I don’t understand all the E stuff either, but perhaps because rear is transferring torque into fwd motion whereas front is containing/handling the inertia of that v12 weight when wheels are turned left and right?
Front mounts have to resist stopping and turning, where as the rear mounts only have to take straight loads of accelerating and stopping, wheels not turned.
Thats my guess.
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They also take lateral forces, as great as the front.
And I think that this is the real reason behind the heat shields Greg is referring to. They are there to take these lateral forces because these types of bushes are very good at compression but not at shearing.
When you do the physics on it ,Aristedes, that’s not true: the front suspension mounts see much more lateral force and transverse force than the rear does. It’s all covered in Steve Smith’s book about how to build a race car.
Someone will correct me if not accurate, but I believe those type of self threading bolts are “one-time” use and meant to be replaced with new.
The rationale I was told being that the thread depth is really only acceptable the first time in. You see them used for seat frame runners to floors, etc.
Having said that, I’ve reused them plenty of times on various applications, as if they get tight and torque to spec, unless there is some shear issue I’m not aware of, they should be just fine.
Thanks. Grade8 3/8"-24 x 1" bolts with lock washers should work perfectly. I’ll thread them in by hand. I’ll double check it with mount off just be to make sure they fit tight and smooth.
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Question on steering rack bolts. I may just clean up the three I have, but I have found they are an odd length. 5/16"-24 x 3-5/8". Standard bolts come in either 3-1/2" or 3-3/4" length.
So I bought Grade 8 in both sizes. Has anybody had any success on using these length bolts? Not sure if that 1/8" shorter or longer makes an issue. Thanks!
