Front springs on the Mk10 and 420G

I presume that they are the same. Anyone got another opinion?
I found an original front spring, marked MkX with Tippex, which has been on a shelf at a Jaguar place, that I know very well, for at least 40 years.
The dimensions (height, diameter of the coil, and the number of laps) are different from the newly manufactured springs that the usual vendors offer. The new ones are too soft and make the car too low at the front and create a noise on uneven surfaces. I have been through all this with my 4 cars over the last 20 years.
So now I am having a Swedish coil spring manufacturer which sell world wide, make me 6 of these, with the same dimensions as the single, original spring that I bought yesterday. Unfortunately they only had that single spring for the Mk 10.
The problem now is to borrow the Churchill tool to change the front springs. I know of 2 examples in Sweden, but one is not to be borrowed and the other is stuck in a container where my now 76 year old Jaguar mechanic put his former garage while waiting for the new one…

This is an original front spring with 41,5cm, 18mm and 8,2 turns

Many of us have managed without the Churchill spring compressor, good quality threaded rod and few other bits and pieces work just as well, plenty of pictures in the archives.

A good trick is to put a roller bearing under the nut.

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You absolutely do not need the tool

1 meter of grade 8 rod, and a few nuts and bolts, cut it into 30cm lengths.

You can easily do it with IFS in car, as you only need to jack it up a small amount to clear

I checked an engineering table, and 3 x 3/8 rod is stronger than the original tool with a single threaded rod

I used a single piece of 1/2" rod straight down the middle of the spring.

I had a plate at the bottom with a nut under it and another plate at the top. I put a roller bearing (one of the outer fulcrum shaft bearings from an IRS) between the nut at the top and the plate.

Another advantage I see in using 3 rods instead of 1 is it eliminates the problem of lateral pressure, as the forces on the spring describe an arc when it is R&R

So that adds to the safety factor, just as having 3 thread vs 1 also does

Our Jag Club Churchill Tool has disturbingly chewed main thread

I have used it, and it has pucks that stabilise against the lateral forces, but not as well as having 3 rods imo

I also use 2 old rear brake discs and rods to compress Jag rear springs

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Here’s mine again. As Robin said there are multiple entries in the archives. FWIW.

…but Paul, you virtually have the 3 rod system in your pic…and Yes, it does allow the original bolts to be lined up with the greatest of ease

I note that the greatest amount of compressed spring force is when it is most compressed, so I fit slight longer bolts to the other 2 holes, as can be seen in my original pic. They are pretty well redundant if you consider the extra force the 5 original bolts & threads are subjected to when getting pounded on the road in every day driving

I used Tony’s method last year, and it works very well. Slow, but feels safe. I welded a nut on the outboard end to be sure that the stud couldn’t back out, but I didn’t have a problem with it. A ratcheting box end wrench is helpful. I actually used 4 bolts - there are a total of 6 holding the plate as I recall. As he said, Grade 8 threaded rod and nuts, nothing less. By the time I was finished, even these were showing some wear, and I would get new all-thread if I were to do another set of springs.

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I hear what you’re saying Tony.

By the time I’d finished with my bit of Bunnings all thread it was missing a few teeth :slight_smile:

Collingwood supporter?

I deal mainly with " Industrial Nuts & Bolts" which is only 20min drive away

They have warned me about the poor quality of Bunnings fasteners, but I did use some of their “gal rod” in a project a while back. Its badly rusted already

I support The Sydney Swans of course, being a New South Welshman :grinning:

Indeed. The big central length of continuous thread made removal and refitting (to a point) relatively fast. The idea being to emulate the Churchill tool. I have to admit that I ran out of nerve at the prospect of winding the single 16mm nut much further without the smaller studs to assist with increasing spring tension and alignment. It’s a “heart in the mouth” type of job.

Peder, I went through the same experience changing front springs on my 420(not G model). The first set came from a very well known east coast US supplier. At first they were fine but after 1 year, I could not turn my wheels as they had sunk by 2 inches! So second supplier in the midwest sent springs that were much more robust, same number of coils, but thicker and 2 inches higher…again after this time 2 years they sank 2 inches!!! So, I have a friend that loaned me a NOS spring(I was hoping for the right color code as there were 3 different springs made by Jaguar). One for manual transmission, one for manual transmission with over drive, and of course one for an automatic transmission. I sent this priceless spring to COIL SPRING SPECIALTIES in Kansas USA. Spoke with one of their engineers about the metallurgy. He told me no one makes them out of the correct metal. Well, that was 4 years ago and he was right.


So the new ones from Kansas, 4 years ago, have now weakened, with a low front as a result…?
Or did I misunderstand you?

Peder, the springs made in Kansas have not sagged at all in four years. The car has NOT settled at all.
If you can get a NOS spring have them match diameter, dimensions and metallurgy.


Well done on the Kansas springs.
Yes, as I said, I found an original spring and have the main spring manufacturer in Sweden agree to make a small batch of 6 for me. They export all over the world and nornally have a 100 minimum limit.
The spring, as you can see at the top, is not NOS but ORiginal Stock. I know that it came out of a Mk10 in the 70s or 80s, and has since been stored on a shelf, so it should be pretty close to original length, and strength, I think.