mine is deformed from the previous owner backing up over something that did not want to give way and I am saving up for my "VERY LAST ONE"


what did yours cost you? if you do not mind me asking....

 

My 85 XJSC doesnt have this undertray... ?? Was it fitted to 85 Cars ?? Or do I need to track one down ?

 

You need the spoiler and the tray. High speed stability is far worse if the tray is absent. All XJS were fitted with them, though later facelifts had a different design.

 

 

I first got my car in1998 and it had the chin spoiler but no tray. I did not know then that the tray should be there. When a year or so later I found out it should have one, I fitted it. The difference was astonishing; at anything over 100 MPH the car tracked far better and did not wander at all. I was not aware of it being poor before the tray was fitted, it was after it was fitted that I noticed an enormous difference.

Supporting the chin spoiler would be better than nothing, but in my view, no substitute for the tray. It would not be hard to fabricate one from ally or thermoplastic, once you had made a template out of (say) cardboard.

 

 

https://www.jaguarclassicparts.com/u...ndertray-front

 

 

Thanks a lot Greg.
That explains why my rubber lip is bends back at the middle every time I go 100+ MPH: I do not have the tray !
Will it be the same even for a PreHE like mine ??

I suppose the missing tray will compromize the airflow to the radiator. I had actually been thinking of creating an undertray to help airflow and support the rubber lip. I was planning to make it in steel though...

 

Yes, the pre HEs had them.


I would make an accurate cardboard template, then make a tray either out of thermoplastic sheet, or out of aluminium. The less weight forward of the front wheels the better. You really will notice the difference once it is in place and entire assembly properly braced.

 

I was planning to use thin gauge zink coated steel plate, but your suggestions does also make sense if the plate can be made without having to weld...

 

Does anyone have some pictures of the properly assembled Undertray/Spoiler/Lower Grille?. I've been lucky enough to source an Undertray. for my XJSC - I have Lower Grille about to be repainted and the the Lower Valance as well, - Spoiler is also cleaned and ready to refit. BUT - i'd like to see how the factory put all this together - including the inner lower front plastic guard liners

 

Some pics attached. The undertray/wheel arch baffle 90 degree join is hard to get properly rigid. I used a 90 degree aluminium angle "iron" piece with clinch nuts in it, and then small bolts into this piece through the plastic.
If you are concerned about rust, seal then entire wheel arch baffle/wing join with sealant all the way round very thoroughly, so water cannot get behind the baffle.
I have not got a close up of the spoiler/ lower grille join; but the spoiler fixes to the bodywork lower corners by self tappers into captive fixings in the body corners. I bolted it into the lower grille using 6mm stainless bolts.

 

Perfect...

This thread is EXACTLY what I needed today! I just got my lower valance from Pauls (cant remember what he charged, it was a bit, but he told me they bought ALL the remaining stock from Jag many years ago)... Then, I had been watching Ebay and waiting for months but FINALLY got the under tray and baffles from a dude in california as one set. Both left and right baffles and tray for $150. My spoiler has been painted and sitting lonely in my boot for more than a year, lol.... I am stoked ~~~ but a little unsure.

Greg, are you saying that mostly everything can go together with the 6mm nut bolt combination? Then what, a bunch of self tapping stainless screws? Any other fasteners? Retaining clips? What do ya think? Yes,,, I did not know that the spoiler and the tray fit so intimately and depended on eachother like that.

I am terrible at taking pictures because everything that I am doing is my first time doing it and,,, I got so little time, but I will try to produce some pictures (for the sake of the thread and forum) on this excursion, lol...

Thank you all!!! Really

 

Great find on the tray.
I used stainless self tappers to fit the tray to the spoiler. There is not room there for anything else as the lip on the spoiler bottom edge that the tray fits into is acutely angled. There is just room to get in those spring clip thingies that self tappers go into.
From memory, the bodywork lower quarter panels have captive spring thingies for the self tappers that fix the spoiler top edge to the bodywork. But I did use small stainless nuts and bolts to fix the lower grille and the fix the spoiler to the lower grille.
The spoiler rear edges I connected to the wheelarch baffles with small nuts and bolts using a bit of aluminium angle "iron" to reinforce the corner and take the clinch nuts I used.
Remember to also fix the centre part of the tray to the under-radiator cross member. You should have two nylon bungs in the cross member to take largish self tappers with penny washers on them, up through the round slightly sunken egg cup sized indents in the tray. You can clearly see these in my first pic above. They are very important to brace the tray.

 

Hi... Thanks! The tray was a great thing. Completely flat with some hardware...! I did my hunt,,, so it didnt just fall into my lap, lol! Iz proud!

I have some concerns (which seems to come with the territory, lol)

One: My radiator cross beam is quite rusted out... Except for the occasional nuts and bolts in locations here and there, the crossmember and the lower valance have been the ONLY significant rust I have found on the car. I haven't looked closely enough yet to know BUT are you saying that the two main indents in the tray, some 6-9 inches inward, affix to the under rad cross? ****! If so, I'll have some figuring to do. My hope was to have the same guy thats doing my floors do the cross member ---- someday. Floors soon, like next week,,, but the crossmember will be down the line. It's a wallet thing.

Two: The center lip connection points on my spoiler are ripped at the fastener points. Nothing major, ripped the size of the old fasteners - like they got yanked out. I was intending to reattach it to the lower grill with with new holes drilled into grill and spoiler OR into the old holes but with a strip or length of steel flat to sandwich the spoiler edge, the grill, fasteners and the strip tightening down, anew --- ALL to the grill. Ya know,,, punch some holes in a length of thin metal sheet and back the weak plastic with metal sheet and sandwich. Hard to word....

But yes,,, Especially after looking at this site,,, I was wondering about the VARIETY of little bits and pieces that I would need to get it all together. I think I'm going to try to put it together mostly off the car to test, see what I need, go to the STORE and spend,,, then get back to it.

Greg, as usual. Deep bow and a hats off thanks

 

Take a careful look at the crossmember. It is a structural beam and the only thing holding the two front sides of the car together. It can easily be welded and reinforced, it cannot be seen normally, BUT make sure the metal where it attached to the side chassis beams is sound. If it is, then some decent 5mm steel welded along the straight part of the beam will do it.
If the attachment of the beam to the chassis rails is rusted out, then a careful attachment of a replacement beam is needed. All quite doable, radiator out, and new beams are available.
As part of your repair you can weld two captive nuts on the bottom to take a nice stainless bolt to fix the tray!

 

Yeah. Its most only the hollow center of the beam, its front outward face, that is gone and when I had the rad out to do the water pump and 'stuff' I literally stood on it to see what would happen. The tie in points on both sides are very sound, but still, I will do as you suggest when I can. Question is, how can I get it to my welder w/o the rad - I wont pay him for that labor, maybe if I take out/off the front end,,, lol - what Im about to install,,, he can get to it it from the front and under? We shall see. It work that will need doing. ~ maybe its time to invest in a MIG welder? I have considered it. New learning curve there.

I think the crossmember will take the tray. Its a matter of trying!

Thanks again!

 

I would use aluminium not steel, easier to work with and lighter, It will do the job.

 

I am resurrecting this thread as I am in the process of reassembling a totally disassembled 1985 XJS.

This is the project car

I am in the process of installing the stone guards and wheel arch baffles but I am missing pieces as shown in the photo

RTC1542/3 and RTC 1531
Since RTC 1531 (front valence) is NLA I purchased a sheet of 1/16 ABS plastic to fabricate the valance and the under tray (if that is possible).
The problem I have is that the triangular piece #10 above is missing and I do not know what it looks like or where it is attached to the body to try and fabricate a piece.
Does anyone have any photos to show how the pieces go together and advice on how to fabricate the missing pieces?