Merlyn Mk11a Shock Lengths

[Merlyn-Mark-Magician]

I'm in the middle of restoring a Merlyn Mk11a FF and need to order new shocks. The rear shocks are 14.75" long (eye to eye) but I'm not sure what length the fronts need to be. Unfortunately I don't have the old shocks as a reference. Can anybody with a Merlyn tell me the correct length?

[Andrew Stein]

Mine measures 13 1/2" extended, c-c.

[Brian]

Keep in mind that the MK 11A came on extremely soft springs, and had quite a high ride height. Modern spring rates and ride heights mean the springs will rattle comprehensively on those shocks when in full droop. You can very usefully shorten the shock lengths so that you don't have spring caps falling off when you pick the car up off the floor and get all that droop.

[Andrew Stein]

I'd agree with Brian; with #225 9" springs they're almost free at full droop and ride height is as low as I dare using Mk.17 nose. 13" is the very longest you should need with my spring. Could run lower with higher spring rates, but that's another matter.

[intrepid]

This thread is pertinent to my interests, as I have a MK 11a and am planning to purchase new shocks soon. I believe the original shocks were probably 15 inches or perhaps even longer from what I have heard. It seems that 13-14 inches is the length most recommended for modern use. Can you actually get away with even shorter shocks and, if so, are they advantageous?

-chris r.

[steiny142]

I am doing a frame up on a 11a, it had spax 14 1/4 inch front and rear with no problems for the last 10 years or so. I am replacing them with 14 inch Gaz shocks and expect no problems from the lack of droop. the Gaz are available from Demon Tweeks in the UK. check them out, steel, adjustable, rebuildable, at a really great price.

[Merlyn-Mark-Magician]

Thanks for the input. My car was last raced years ago with a 3" ride height front and rear and fairly soft springs. I've been told with the smoother tracks today ride heights are lower and spring rates stiffer. What spring rates are you running front and rear and what length springs would you recommend with 13.5" to 14" front shocks. How low can you set your ride height with the Mk17 nose? This car will be run only at historic events and autocrossing events.

[Andrew Stein]

Direct quote from Mk. 11, 11A & 17 Merlyn US set-up manual from when they were new:
With car ballasted -

"The ride height is measured from the center of the bolt from the lower wishbone to the chassis on front and rear. The relative angles of suspension geometry should remain constant, so that the measured ride height varies with the diameter of the tires used.

... For front tires of 22 1/2" diameter the ride height is 7 5/8". For rear tires of 23 1/2" diameter the ride height is 6 3/4". For different diameters than these, the ride height is computed by making the necessary correction up or down by half the difference in diameters (the radius). This preserves the correct suspension geometry."

My car is about there now in front, adjusted for Hoosier vintage FF diameters; running lower by 1/4 - 3/8" means replacing jabroc under nose every weekend.