The 'E' Type Forum

ok, its happening again, my exacting original restoration to standard spec is going out of the window!!

So as per my "rear ride height" post I have fitted Koni Classics and now cannot adjust them without taking them off etc etc. So talking with some very well respected restorers not too far from here, they tell me that whilst the Konis are a superb ride, the easy use of the Gas adjustables puts them in front. Now as I have not bought my front shockers yet, and I have to take my rear Konis out to adjust the ride height now is the time to make the decision on dumping the Konis back on the shelf and going with the adjustables. So as always, please can you all advise me on your experiences and preferences. Its a bit of a blond vs brunette question, but I know you will love answering it.

My experience of Koni's is not good. Six on the car originally and most have failed. Personally I think they do not suit the E-Type as the ride is too hard even on the lowest setting. I was discussing this with Paul Brown recently and he agrees Koni' are dismal. Talking of which have you ever tried adjusting a Koni? Huge marketing scam - The Netherlands are renown for their shock absorbers being a mostly flat country

My current preference is for the standard Boge shocks which seem to be as good as it gets in the absence of genuine Girling units on an E-Type. Can't see why you should spend four times the amount on something 'adjustable' when the car behaves perfectly as is. Challenge for you - try keeping with us on a winding French road. Our friends, in a well driven 911 turbo, could not and I never once had to get out and 'adjust' the dampers to stay in front. Keep it simple :? As for Gaz, gimme a break Mr Fast and Furious 6 - they are for the Max Power readers.

I fitted Spax about 6 years ago and they are fine. You can adjust them easily on the car and go from very soft to very firm with a flat blade screw driver.
I have heard that the clicker mechanism can fail but again so far no problems.
If I were fitting shocks again I think I would go for the Gaz on because they look good, Spax are a lot cheaper I think.

Dave

Heuer wrote:
My current preference is for the standard Boge shocks which seem to be as good as it gets in the absence of genuine Girling units on an E-Type.

I've taken the same approach as David and have the Boges on the back of both my cars. Indeed what I did was just buy the springs and shocks as a complete unit from SNG. I have Konis on the front of my coupe. I have these set in the middle and have had no reason so far to adjust them so far in over 2000 miles of driving. I have a set of Gaz adjustables for my roadster but it's still in pieces...

If I were having problems with rear ride height I think my approach would be to ensure that my springs were the correct length and rating. Earlier cars did, I think, have shorter springs (9.5" vs 10" but I'm not sure that this is right).

andrewh wrote:ok, its happening again, my exacting original restoration to standard spec is going out of the window!!

So as per my "rear ride height" post I have fitted Koni Classics and now cannot adjust them without taking them off etc etc. So talking with some very well respected restorers not too far from here, they tell me that whilst the Konis are a superb ride, the easy use of the Gas adjustables puts them in front. Now as I have not bought my front shockers yet, and I have to take my rear Konis out to adjust the ride height now is the time to make the decision on dumping the Konis back on the shelf and going with the adjustables. So as always, please can you all advise me on your experiences and preferences. Its a bit of a blond vs brunette question, but I know you will love answering it.

Presumably, having checked and rechecked with the supplier before purchase, they will be giving you some sort of credit now that the non-standard parts they recommended have turned out to be unsuitable?

Konis have never been adjustable for ride height, only damping. Even damping is not really adjustable is a user-friendly or subtle way. The shock has to be completely removed and any spring taken off before this 'adjustment' is possible. I understand it was developed as a way of compensating for viscosity changes and valve wear over time. When overhauling the suspension, instead of throwing a soggy damper away it could be made firm again by cranking up the damping effect and the refitted to the car or bike. None of that has any effect on ride height of course.

Hope you get some satisfaction or a heavy discount from the seller.

Pete

I purchased, a month ago, the rear GAZ adjustable shocks and springs. The main reason is to be able to adjust the ride height.... My car was, is, to low for Mexican roads.


I can comment anything, because sng have not delivery my parts. :(

For the front ride height, I got a pair of new torsion bars.

Ah, some great responses here as always, thanks Guys. But of course it polarises opinions! I must say that although I set the rear Konis at one up from softest setting as per CMC instructions its rock solid on the back. Really hard. The principle reason I was thinking of Gaz was not because of the adjustable damping but more the ability to adjust the ride height as the car settles. I hear what is said about the Boges, to be honest, I was rather put off with how cheap they are and since they are not adjustable for height or damping I would not change the Konis for them now, maybe next time. So really its about the GAZ vs the Konis. Ummh

Why do you need to adjust the ride height? Jaguar did all that for you and providing everything is correctly set up the car should go to the correct height. If not something is wrong somewhere and 'fixing' it with adjustable height shocks is not really a solution.

Norman Dewis pounded thousands of miles of road to get the E-Type the way Jaguar wanted it and a fine job he did too. His work was simplified to some extent because he was working with four constants:

1. A monococque/frame construction with known torsional rigidity (not that good it has to be said!) which was pretty much finalised
2. The weight of the car
3. The unsprung weight of Dunlop RS5 185 tyres, tubes, 5" wire wheels, front discs and callipers
4. The compliance of the walls of 185 tyres

The variables he had to experiment with were:

1. tyre pressures
2. damper valve settings
3. spring/torsion bar stiffness

He had a wide choice of springs (identified by red, yellow, blue, green and white paint blobs on the coils) to choose from and Girling were able to re-calibrate the damper valves to whatever setting he wanted. He then had to drive the same car over the same road at MIRA all day every day for weeks until everything was the way he wanted it to be.

Nowadays people go along to a Max Power sweet shop and with one swipe of a credit card buy whatever they think looks best and bolts them on in the forlorn hope this will give a huge improvement in performance. Adjustable shock absorbers will only be right on one setting, the one that matches that of the original Girling shock absorbers, all others will be wrong in one way or another. If you think you will find a better setting you need to go over the same bit of road many times validating the change is positive. It gets even worse when you fit lower profile tyres and wider wheels because you are increasing unsprung weight and reducing tyre wall compliance which will affect the springs and damper settings. You can then start playing with tyre pressures - it has taken me 40,000 miles to satisfy myself that with my tyre/wheel combination, driving style and route preferences I should use 30psi front and 35psi rear pressures but some days I do wonder whether I should increase the fronts to 32psi.

If you are going to put the car on a race track and be competitive you need adjustable shocks and a range of springs. In fact a highly competitive race car commands a premium if it has a track settings book with it. For a road car stick to standard springs and dampers.

Pete is quite correct about the Koni's - they were originally marketed as guaranteed for life simply because you could dial out wear with their 'adjustable' feature. That feature is not one to be done lightly - it involves removing the damper from the car, removing the split plastic washer, removing the difficult to get at and usually stuck rubber buffer, placing one end in a vice, pressing down to engage the lock pins and turning the other end. It was meant as a maintenance function not to fool around with stiffness although motorsport enthusiasts quickly jumped on the idea. Spax and Gaz followed suit and it became a 'must have'. Trouble is if you mess with the damper setting you also need to change the springs to match

Having just gone down this route (2 months ago) I totally agree with all David has said. I cannot fault the damping on the standard Boges and springs purchased from SNG.

Although the additional height of the body by approx. 1 inch was not best for appearance they have with 1500 odd miles started to settle.

I'm struggling with the same decision as Andrew. I would prefer to go with Boge but have seen varying rear ride heights on different cars. What is the correct rear ride height for a '67 OTS??? Mine measures 11 3/4 inches from the center of the knock-off to the edge of the fender directly above. That seems a bit high compared to other cars I've seen. I'm rebuilding my rear end to change the ratio from 3.54 to 3.07 and have to admit the ability to adjust the GAZ shocks seems attractive.

Jaguar only listed the general ground clearance of the E-Type as "5 1/2" but don't say where that measurement was taken from. The front suspension is set as:


For the rear suspension:


So provided you have the correct road springs the ride height at the rear should be as Jaguar intended. Of course reproduction road springs may not be the correct specification so always worth measuring before installation. For standard (Boge nowadays) dampers you need the springs with a red paint splash. The trick is to get the rear height as standard and adjust the front accordingly to get the correct 'stance'. For GAZ you need their special springs.

Both my FHC and OTS measure ~7 3/4" from sump plug face to the floor if it is of any help.

Heuer wrote: Of course reproduction road springs may not be the correct specification so always worth measuring before installation. For standard (Boge nowadays) dampers you need the springs with a red paint splash.

When I bought my rear springs from Barratts a few months I was only able to get the longer 10.5" springs, and they have a yellow dot on them. These seemed to be the only option available. I never did work out whether my roadster built in June 1964 should have long or short springs.

The short springs were only on the very early cars - up to 850137, 875542, 860008 and 885039.

This is from the GKN catalogue:


BB = cylindrical spring ends ground square to the spring axis.

Also the colour codes on the coils refer to the static load of the springs, more to ensure all four springs are matched as much as anything else but will also determine the suspension stiffness. CMC fitted 'yellow' coded springs to my OTS I seem to recall. From the Jaguar XJ6 manual:

Heuer wrote:The short springs were only on the very early cars - up to 850137, 875542, 860008 and 885039.

So my roadster 881824 should have short springs?

No - your #881824 comes a long way after the change at #875542 - 6,282 cars later in fact!

Thank you David for your kind reply. While there is considerable information on front ride height, I at least have not found definitive information on correct rear height. If "original" parts were still available at my friendly Jaguar dealer, I suppose I would have more confidence that installing them would result in the correct rear height. But with all the aftermarket and updated shocks and springs, I feel less confident. I also noted the post from the gentleman whose rear was just starting to settle down with new shocks and springs after 1500 miles. I think I'm too old to wait two or three years for mine to fully settle. That's why I am considering the GAZ adjustable, although my first instinct would be to go with the the original Boge. I think the rear of my car is a bit high now and I'm afraid that, after installing new shocks and springs, it will be even higher. I'll continue to see what I can find out about correct rear height.

My OTS recently had new springs/shocks and the ride height is as it should be, was from day one, no settling required - I can't see what the problem is. Bear in mind in addition to the Gaz shocks you will need the appropriate springs so your cost is going to be quite high for something that may not be necessary. As for rear ride height it should be 7.75" to the base of the IRS/drain plug.

Let's do a poll - "what is the rear ride height of you car measured from floor to base of drain plug?" Mine was measured with 3/4 tank of fuel, 35psi tyres on the S1 OTS, 32psi on the S1 FHC. Both measured ~ 7.75" Looking forward to seeing the responses!

The parts manual has the early cars with 9.5" rear springs which were altered to 9.950" matching the chassis numbers quoted by David , 150 lb rating Maybe we have variation in todays supply of what should be standard .

Andrew,
before you buy gaz shocks for the front ask for the open and closed lengths as they were wrong , very close to bottoming out on compression and stressing the rack tie rods when the car was jacked up because of over length , stick to standard shock for the front I'd say .

steve3.8 wrote: Andrew,
before you buy gaz shocks for the front ask for the open and closed lengths as they were wrong , very close to bottoming out on compression and stressing the rack tie rods when the car was jacked up because of over length , stick to standard shock for the front I'd say .

Bugger. Bought them months ago from Barratts' they're sitting in boxes in the shed.
Do you know what the correct dimensions are?

Just a thought but with the car in a normal road going position with a driver in place. Mechanically it would make sense for the rear driveshafts to be horizontal. :?