Hi guys,
Has anybody out here used the threaded rod method for replacing their front coil springs?

I have the springs, hopefully the right ones, and I'm trying to determine the right threaded rod to get. I took one of the bolts out of the lower spring pan and took it to Home Depot to measure it. It appears to be 10MM x 1.0 thread.

I have seen a lot of posts here taking about 3/8 thread but that was not correct. Does anybody know from experience what that thread is on a 1996 XJS?

Thanks,

Hitch

 

After doing this job maybe 20 times on my own cars over the years, I can tell you for sure ( at least on the models up to 1990) that the threaded holes in the front lower A-arm are 3/8-24 (not metric). Check the one you have very carefully- even though Jaguar changed many of the fasteners on the facelift cars to metric, I seriously doubt that they changed the lower A-arms.....

If you want some tips on how to do this with the threaded rod scheme, give a call- 408 839 5569

I hope that helps

Andrew
Jaguar Specialties

 

Its 3/8 UNF

I used this method here.

Jaguar XJS Restoration : Rebuilding the front end

 

I will double check the bolt that came out of the spring cup before I start.

Thanks, I really do appreciate the help. I don't want a spring getting away on me.

 

Hitch,

You've only got to check the parts website and you'll see that Jaguar show it as .375" (3/8). And you're right, you don't want to take any chances on that front spring! I confess that I've never been brave enough to do it with anything other than the correct factory tool!

Good luck

Paul

 

3/8-24 and 3/8 UNF are the same thing, The F is for fine thread as opposed to UNC (coarse) which in the case of 3/8" would be 3/8-16.....

Using the threaded rods is fine, of not a bit slow, but you have to be careful that your rods stay full screwed in at all times...

Good luck

 

I feel a bit like you do Paul, but as the bolts are the same as the rod, in reality, as the bolts hold the spring Ok under the shock loads of the car actually running over bumps, potholes, etc etc, identical rods should be far more than strong enough. I therefore suspect we are being a bit over-anxious. Even so, it would not harm to buy high tensile steel rods, and to also install a thick threaded rod through the spring pan, spring centre and tower, with nuts and thick wide washers each end as a safety device, so if something unforeseen does occur, the spring cannot cannon out.
In fact a ratchet tie-down strap (the stuff like narrower seat-belt material) threaded through that same way and tied with a decent knot would do just as well. That strapping is tough. With the springs, it is not so much the total of the stored energy, (it cannot be much over 6 or 700KG that the springs are holding up, if that - tales of many tons are obviously not true or the car would be pointing skywards) but their cannoning loose that is the danger.


Greg

 

Take lots of pics and document the parts you are buying. (threads, length, etc)

 

Greg,

I'm sure you may well be right. We just hear the horror stories of what happens if the Jag springs are able to let go. I think I'm just scarred by that figuratively, plus the pics I saw some years ago of a Triumph spring which escaped when lowered using just a trolley jack. It broke the owners arm, cannoned around the garage and punched a hole in the prefab' wall! And he considered that he got off lightly!

Paul

 

Agreed, but using an unrestrained spring held in place just by a jack (and who knows what that was sitting on) is quite different from four x 3/8ths steel bolts, with a combined tensile strength of some tons and further backed up by a properly restrained spring. I am even now trying to calculate the thread yield strength, if I manage it I will post it.
EDIT:
According to my thread strength calculator (http://www.tribology-abc.com/calculators/e3_6e.htm) and always assuming I am using it correctly, an M10 grade 8.8 steel bolt threaded 8mm into cast iron has a maximum tensile load of 37Kn, which multiplied by 225(Kn to lbs converter) gives the weight it can support before failure (and I presume the wishbone is better than cast iron being forged steel) of 8000 lbs or 3 and a half tons. There are four of them, so the margin is pretty vast, if what I have googled up is correctly understood by me (big if!)
Greg

 

When I undid the old springs, I would use a long centrally fitted threaded rod (no matter if metric or imperial). I used an M20 thread. Pull it tight (a little) and then undo the screws. It would "ping" once but the spring is still secure and can be undone using a central nut...

I am still hassling with my rods...

 

Hitch,

I was planning on doing something similar as you but have found that my suspension is pretty tight and according to the fellow I purchased it front four (4) yrs ago some of the suspension work was done.

To the point: There is a guy out there on the internet that made a through the center rod out of simple hardware store parts. Here is the location to find the information. He also has a lot of different things he has worked on. He shows picture and describes.

bernardemden.com/xjs/spring/index.htm

The rod is substantial more than 3/8" diameter and ~ 18" long.

Perhaps some of the group has experience with this site and might shed a different light on this matter.

Good Luck

Softball60/Paul

 

The wishbones are definitely hardened, I had one with a bad thread. So I redrilled all and re-tapped 7/16.

 

Paul,

Bernard is well regarded in XJS circles and his website provides a real wealth of information. Just to advise, there is a slight typo in your website address. It should be:

Bernard Embden's Jaguar Website

I can't speak for his suspension threaded rod, but certainly the principle is the same as the factory tool, although the attachment plates on the factory tool are more substantial and bespoke.

Whilst I still only use the factory tool for my XJS, I have made a threaded rod tool for my Triumoh TR6. Mind you, the factory workshop manual for the TR6 as published in the 1970s details how to just use a simple trolley jack under the spring pan to remove the spring. And so I followed those instructions 26 years ago! But never again!

For my TR6 I've now made a tool from 19" of M20 rod. I've taken as many precautions to safety as I can think of. For example, I've used ACME threaded rod for strength. I liberally grease the threads and check them after every single use for any deterioration. I use two very long nuts on each end and lock them together. I have two large washers on each end, liberally greased to allow slip. I then have a VERY large hemispherical washer filed to allow the maximum contact path. This abuts a bespoke 1/4" thick plate which engages in the lower pan and fits over the nuts. A large slotted hole in the plate allows the M20 rod to vary and optimise its alignment path. The large hemispherical washer means that the nuts are not abutting the plate on one edge and straining the thread contact. For a final belt and braces approach, I have drilled the M20 rod at each end and inserted large R-clips to give some final small contingency in the event of failure of the nuts on the rod. When refitting the spring and pan I also insert extra long studs on each pan bolt attachment to help guide the pan up, and then replace them one by one with the standard bolts.

Is that all over the top? Maybe, but at least my arms, legs and vital organs are all intact!

Paul

 

Guys,

Thanks for all the advice and helpful concern. I've got my threaded rod. I've got a couple of ratcheting tie down-straps. I might invest in a large bolt thru the center also. I plan to do this on Saturday morning.

I will admit that the horror stories have me a bit cautious....I suppose that's good as it will force me to be on my best safety practices.

I'll include before, during and after pics. Hopefully none from the ER.

If you don't hear from me by Monday send help......

 

Life gets in the way of plans once again.. I did not get to even touch the Jag this weekend. maybe next weekend....

 

I see that I never finished this thread.
3/8 by 24 (fine) threaded rod did the trick. Very simple using threaded rod to let the plate hold the springs in place down.

I ending up cutting a set of spare springs down about an inch and then using the factory shims to adjust the height. Took me a couple of tries to get the left and right at the same height but I am satisfied with the results. Front spoiler is about 3.75" off the pavement. Car has a slight rake front to back. Looks mean and handles great!

 

Nope! Not without pics! There are supposed to be pics!

 

Hitch,
Where did you get your springs? Do you have a part number? I want to rebuild my front suspension.
Thanks,
Ron

 

Did you ever post your pictures? How are the springs working out. I want to find a good source for all 6 springs for my 95.