The Mk1 and MK2 2.4 cars use a front suspension spring part number C16953
Mk1 and Mk2 cars with 3.4 and 3.8 engines front suspension spring part number is C16954.
I know the variation is due to the difference in engine weight and I would suggest the 3.4/3.8 spring would be thicker.
Can anyone give a definite answer to the differences so they are easily recognised.

 

Bill, Spring rates were marked by brushing Red, Yellow, Blue etc stripes down the black spring. Somewhere I have a table of what they mean that is going to take a hell of a search to find out what each colour means. ~ I'll do my best. If they are no longer visible or the spring has been sprayed/powder coated all black you are in trouble & need to take them to a springworks so they can identify rate in a compression device.. My filing system is awful. Obviously a MkX had a different spring rate requirement to a 420. Done for easy identification on the assembly line. There were also some other paint marks on the spring to even up rate from LHS to RHS should there be a slight variance. All springs were obviously not absolutely identical. This would indicate a specific packing piece required.

Like this & sometimes 2 colors next to one another. e.g. red & yellow.




Front:



And full length colour example.

 

From memory, David Manners told me the spring rate of the front springs of 3.4 cars was 300 to 320 lb/in. This was years ago when I was thinking of stiffening the suspension of my car. I think the colours relate mainly to free length and the spacer thickness required to achieve the factory ride height. Sorry, it's not much help to Bill.

 

Yes. What Bill needs is the colour of the full length line if still visible & what it means for front. I think it might be a trip to the closest spring works.

Example:

plus Free length & colour.

 

Thanks all.
The problem is that all traces of colour are generally gone due to sandblasting effect on non-sealed roads rust etc. in the typical Aus environment.
This question came to me from a local Jag club member. I suspect he has a MK2 2.4 front end put into his Mk1 3.4 for the disc brakes (but he did not do it)
He has been quoted 115 GB pounds for freight on top of 80 GB pounds purchase price for the two springs from England.
Cheers

 

Bill ~ see edit above. Does your Manual not state

Free length
No of coils
Wire thickness & properties?

I understand what Aus outback roads will do to springs.

Project abandoned?

With wire thickness etc. any decent springworks can set the spring rate or up the wire thickness/properties to personal taste.

I had all my spring rates reset to standard during my resto by the same company that made the springs for SA built cars.

 

If you have access to both 3.4 and 2.4 springs side by side, it may be possible to do a comparison. The main part of determining a springs stiffness is the spring constant, K. That is defined as: K= (Gd^4)/(8D^3n)
Where G is a material property of the steel, d is wire diameter, D= outer diameter of the coil - wire diameter and n is the number of active coils. To count active coils you disregard the coils where the spring touches the suspension and are constrained - only count coils that are free to move. It's usually total number of coils minus 2.

So I would measure the wire diameter and count the coils and compare. Thinner wire diameter and fewer coils means a weaker spring, Assuming the outer diameter is the same, and also assuming that Jaguar used the same steel for both springs.

As a data point I have a 3.8 S Type spring and it is a wire diameter is 0.625"

 

I'd start with the easiest. If the wire diameter is less than on your own 3.4, the springs are most likely 2.4. If they are the same, then count the coils, which may be difficult - I've never tried. If there are more, they are 2.4 ... Like Jagboi, I'm assuming the coil diameter is the same as the coils have to fit the wishbone and subframe?

 

JB ~ I have it at 0.61" shown in post 4 ~ Service Manual date 1972. For S Type 3.4 & 3.8

 

The spring I was measuring was powder coated and was actually 0.635". I subtracted 0.010" for the thickness of the coating and figured that 5/8" was a nice round number that Jaguar probably used.

 

Understood.

 

I can't find the spring colour coding & Bill could not see it anyway ~ case closed from my perspective unless I trip over it somewhere. Let a spring works check rate/s.

 

Thanks everyone for your contributions.
i could not do a comparison test as both my MK1 and MK2 are 2.4 cars and I could not get at a 3.4 car easily even though I have owned about 8 of them.
Cheers

 

Since this is closely related to Bill's original question, I'll enter this here rather than start a new thread. What's the difference between 420 (and possibly also S type) front springs and those on 3.4 and 3.8 Mk2 cars? Those for the 420 have a different part number and cost a little bit more (from the more serious suppliers). The reason I'm asking is that there are a couple of opportunities for me to buy a complete Varamtic steering, subframe and suspension. If the 420 springs are stiffer, it would be a bonus. If the difference is something else, it would be nice to know what it is.