Replacing rear springs

[Martec]

Hi Alec,

I've been forced to do a lot of work and reading on suspensions due to the MkII and my old Marina (queen of understeer). Also I've ignored Kens Advice at my peril (he knows so much about cars and old Jaguars).

I bought my car as a total wreck and he was often on hand to give advice, if you look at the rear end of the MkII the welded on 'chassis' rails stop just behind the rear axle and the rear end is very weak. I'm amazed when jacking up more modern cars how stiff the chassis is so they can hang anything they want off it.

As you say Harvey Bailey is a well respected suspension guy, and I prefer his front springs.

My car came with what we assume are the original rear springs and after 12 years of driving a 'nodding dog' of a car (serious neck ache on the entente cordiale runs) due to the fronts being very soft (now suspect from a Daimler) I have lost count of the number of times the front springs have been out to fit the Watjag uprated one, back to old spring, try the uprated ones again and only in the last year finding calculations to determine the correct spring rates, its all down to the weights at each end of the car and as I have a 50KG tank and LPG in the boot this upset everything.

I took the rear springs as a datum as I had been warned of poor replacements and the car sitting too high (the book gives the correct chassis heights and drawings). Due to the extra weight and frequency of the rear end I needed stiffer front springs and so raided Kens spring locker ( I tried the correct size fronts and it was so much better), but the slightly uprated (we suspect Harvey Bailey ) springs were the best for comfort. At the time I took the car again for Ken to drive and I drove a standard 3.4 with the Watjag uprated springs on that he had there at the time. He advised on damper ratings for our car and I found his car very nice to drive with those springs fitted, needless to say both cars with 1/2 to 1 degree of negative camber.

My first fitting of the uprated springs and the standard positive camber resulted in serious understeer (frightening at the time) Kens comment was 'well you did give it some negative camber?'.

So I've finally found a comfortable set of springs and damper setting for my modified car, but a standard weight car felt very nice on the uprated springs, and ours was OK on the standard springs.

The calculation for spring rates uses the wire diameter to the power of 4 so as you can see a small change in wire diameter give a massive change in spring rate (from memory the 0.71" spring is twice the rate of a 0.61" spring).

Sorry its a bit rambling, but it has taken 12years and a lot of effort to learn this, by the way the Marina is now neutral to power oversteer, using antiroll bars and standard springing (55 mph with the back end hanging out around Garrards bend at Mallory Park, great fun), it has a stiffer chassis than the MkII.

I asked Ken about stiffening the back end and seam welded everything, welding and brazing plates in has been tried and he said it needed a very thick plate behind the rear set back and secured with many bolts rather than welding!! I didn't bother.

Best wishes
Brian

[piman]

Hello Brian,

thanks for the information.

"a very thick plate behind the rear set back and secured with many bolts rather than welding"

That is a bit unusual, as is the Jaguar's body as it has a bulkhead behind the rear seat unlike most classic saloon cars. I don't understand why bolts and a thick sheet of steel? I would have thought some cross diagonal bracing using something like 2" x 1" box section tube would do a better job and be lighter? I'll have to have a good look.

I found the handling of my Triumph vastly improved with much stiffer springs and a front anti roll bar (Not fitted as standard) plus Konis which I find very good.

Alec

[Martec]

Calculations are all very well, but the final result has to be down to how YOU feel and what you want in the handling department, but its a good guide.

Is yours a MkI or II triumph saloon? again 1970's monocoque and much stiffer than the Jaguar MkI and MkII, as they were some of the first attempts at it.

I didn't stiffen behind the rear back rest but again as recommended by Ken, I put a second 18 gauge steel plate across the rear seat pan and plug welded it down to stiffen the area where the rear spring housing are welded to. Also in the engine bay on top of the front chassis rails forward to the engine mounting, again I seam welded here and under the wings to the chassis rails plus the top of the turrets in the front subframe.

A lot of the rear end is a bit of a disaster for rust proofing so I closed all the holes in the rear jacking mounting and above them and drilled 1/2" holes in the bottom of the chassis rails and sealed all the gaps between the corrugated floor and rails with seal sealer. The idea was to stop water getting in and any that did had an easy way out. Didn't fancy another 3 years of welding.

Brian

[piman]

Hello Brian,

the Triumph is a MK 1 and agree the body is very stiff, just about everywhere is double skinned and triple in the case of the sills. They can be a lot of work to restore properly because of that.

Alec

[silverfox]

Hi , i spoke to Harvey and Bailey about my soft rear end { S type } alas they cant help , but said i should speak to Ray Ingman just wondered if anyone knows how to contact him ? , ta Russ

[owen1]

I recently went to the Goodwood revival, which incidentally was a great day out, with four people and luggage in the Mk2 and on some undulations the exhaust was touching the road.

I think that I may also be replacing the rear springs but before I go down that road could anyone please tell me what the gap should be,either from the wheel arch or the bottom of the(full) spat to the top of the tyre.

Thanks
Owen

[Martec]

Hi Owen,

Its not quite as simple as that, I looked in the original MkII manual and no height is given, plus from the history of the MkI and II it would be unwise.

The MkI was Jaguar's first monocoque body shell and to save money the panels were all ordered form an outside supplier (possibly Press steel Fisher?) anyway they were not asked to assemble the panels into a shell (they would have made sure they fitted then) so when Jaguar tried to assemble them they didn't fit (I have found at least 3/8" of lead just above the radiator and other places). So there is no guarantee that the shell is the same on each side.

If you start at the front and lie on the floor you can check that the front lower wishbones are horizontal (for best handling), them measure the height of the front and rear of the sill. The rear end of the sill should be higher by about 1.5 to 2" with standard loading.

That is a rough guide, one of the 'U' bolts on my exhaust also scrapes the ground if I hit a bump to fast!!

Best of luck
Brian

[owen1]

Thanks Brian, your comments were very helpful.

The car doesn't look that down at the back so I will take some measurements as you have suggested.

I also think that it is a U bolt on the exhaust that is scraping so I will either twist it round or cut some length off.

Owen

[ecosselynx]

Hi

Yes, twisting a U-bolt round can often be the difference between grounding and running clear. While to may be a little more difficult to get at the nuts, these little attentions to detail when installing can save a lot time thinking and looking for things that are wrong with your car.

[MartinHaven]

My '65 Daimler V8 is seriously sagging at the rear. When more than 1-up, I can clearly smell rubber, from tyre rub...
Looking at changing the 50-year-old rear springs plus all the rubbers - should I also order a complete Panhard rod assembly plus torque control rod?

Looking at the car at a recent show, my rear was several (4-5 perhaps) inches lower than a number of Mk2s (Jags, admittedly but how much difference can there be?) and the tops of the rear rims are barely visible below the spats.
Other than rusty nuts (despite the copious leaking of every 50-year-old seal on engine, box and steering) what major dramas should I be prepared for. I have a Haynes manual and a degree of previous experience (Morris Minor owner for 30 years!)

I am looking for comfort, rather than a race set-up (most unbecoming for a Daimler!) so will go for rubber rather than poly bushes and I plan to change them all at both ends to remove some of the clonking and rattling...

Hints, tips?

[Martec]

Hi Martin,

As I've said before these cars in standard trim can be very comfortable, but everything wears out especially rubber. The lower front wishbone rubber bushes are known to squash and fail and the rear torque arm bushes only lasted 2 years before they cracked on our car.

The thought of polythene bushes is not for everyone, but our setup of part poly and part rubber works well for us and in over ten years only the remaining rubber bushes have had to be replaced a few times. We recently covered 1600 miles in 10 days touring Scotland in comfort and that is with approx 80% poly.

Below is a picture of our car many years ago on a rally, the fronts are about 1/2" too low and the rear about an 1" higher but there is a big gas tank in the boot.

It used to be that replacement springs kicked the back of the cars up but I've no experience of new stuff (we still run with what I think are the original rear springs).

Best of luck
Brian

[piman]

Hello Brian,

it may be due to the uneven surface but that looks too low at the rear to my eyes?
Alec

[kactaf]

REPLACING THE REAR LEAF SPRINGS ON MK 2 JAGUAR.
( this is available as a google document with pictures) if interested e mail me kevin.cleary@talk21.com
I am writing this report on my recent task of replacing leaf springs on My Mk2.
The reason is that I could not find anything on the net / YouTube to help in my planning.
I am not an expert or a professional mechanic.
These were the tools I needed to complete the task
Pic 1

On advice, before starting I removed the bolts fitting the torque arms.

I also loosened the Panhard rod. This has a locking nut that needs to be loosened before loosening.


There are three positions where the Leaf Springs are Attached.
This is the most forward position and they are ½ inch bolts/nuts.


2. The centre section is fitted with 4 X ½ inch bolts and nuts. There are also Two rubber pads top and bottom ( per side)


3. The rear is fixed by a nut and bolt through a bushed eye in the leaf Spring.


Be aware that the spring is to be fitted with the centre portion being at the highest point. ( like a sad face )

Using rubber lube or WD40 grease the rubber pads and fit.

Using a bottle jack raise the spring to meet the fitting position. Push up as far as possible.
Bottle jack allows fixing plate to be held in position.o

Fix with four ½ inch nut and bolts.

Next fix the front of the spring. Again jack up to meet the correct position with a bottle jack. Point of contact with the spring needs to allow for the bracket to be in position. Use Rubber lube on circular pad. Fit bracket using 3 X ½ inch bolts. ( these were longer than the bolts used for middle section.

At this point leave all bolts loose.
Now move on to the rear fitting point.
Again use a jack to push the “rolled eye” up to the fitting position.


Use copper grease and put bolt through the eye. Fit loosely.
You may need to adjust the position of the fixing bracket..I used another bottle jack.


The leaf spring should now be in the fitted position, but all bolts are still loosely fitted.

Now repeat with the other leaf spring.

When both are fitted . Lower car to the floor on to the wheels. You can now re fix the Torque arms. Also re adjust/ fit the Panhard rod.

All leaf spring fittings can now be tightened.

After a slow and unsuccessful start. I changed my plan to what is above and the job took me about two hours.

[ian.coles120]

I recently went to the Goodwood revival, which incidentally was a great day out, with four people and luggage in the Mk2 and on some undulations the exhaust was touching the road.

I think that I may also be replacing the rear springs but before I go down that road could anyone please tell me what the gap should be,either from the wheel arch or the bottom of the(full) spat to the top of the tyre.

Thanks
Owen

Hi Owen,
I am going to replace my rears on my V8 250 - just same rears as a Jag MK2. Looking online etc there seem to be issues with replacements. Such as wrong width in one case - the spring shackles / bolts were too wide to fit into the channel in the floor. I understand that the correct ride height is determined thus: take a straight edge from the rear lower corner of the sill and place against the rear lower spat corner ( spats should be correctly fitted ) . The straight edge line should pass directly through the wheel centre ( ie. hub cap badge or spinner ). If you look at photos of restored or low mileage cars this will give you a visual guide. Mine has sunk 1.5" . I have emailed SNG Barratt about the size issue before I start the job asking for the exact dimensions of their springs. Also they sell two variants. One for £89 and the other for £250 ! What is the difference ? They've not got back to me yet so I'll ring them. I wonder if Manners and SNG et al the same manufacturer ? We will see.