Cabrio Front Suspension Coilover Spring Broken

[mike woodley]

Hi, Have just discovered that i have a broken front offside spring. Can anyone please advise me as to the correct "Free length" and poundage for a replacement. My Cabrio has a Rover V8, and is useing "AVO" coilover shocks.Thanks in anticipation. Mike.

[dogoncrazy]

Re: Cabrio Front Suspension Coilover Spring Broken

Mike
This has been the object of discussion on a couple of occasions as Derek Jones noticed that not all Cabrio's have the same number of coils per spring unit. There are sites on the web that enable one to assess the pounage based on the number of 'free'coils and the wire diameter. I personally would probably talk to someone like 'Gaz' shocks [is it protech or something similair?] as they are more than likely to have the info . Bear in mind that you should be changing both for safety reasons.

[djj_engineer]

Re: Cabrio Front Suspension Coilover Spring Broken

Hi Mike
I have looked at some Cabrios at the Derbyshire weekend and there is 2 lenngths of front spring. There does not seem to be any link to date or anything else. Some of the springs are short - about 110mm long and others are longer about 150mm. These are both comprseed lengths. I dont have any free lengths at the moment.
Unfortunatly we are just off to scotland and I wont be around for 10 days or so.
I will be taking a long sprng off the shocker in the near future as I am fitting it to the rear of the 1st Triumph Special ( Pre Marlin)

[mike woodley]

Re: Cabrio Front Suspension Coilover Spring Broken

Hi Alan and Derek,
Thank You for the advice. I have now removed the "Good" spring and it is 9.25 inches in height, with a 2.25 inch internal diameter. The coil diameter is .385 of an inch. The spring has 9 coils. The only thing i do not know is the spring rate, does anyone know the front spring rate for the Cabrio with a Rover V8 installed? or how to work it out from the above info. Regards Mike.

[mark_tinkler]

Re: Cabrio Front Suspension Coilover Spring Broken

Maybe you could estimate the spring rate with a ruler and a set of bathroom scales. Compress the spring down onto the scales and measure with ruler for an inch of compression.

I have an unfinished sierra based YKC roadster with Rover V8. YKC recommendation at the time I got the springs was 2.25", 10inch 100lb front, 150lb rear. Actual springs are suplex, 12 coils, with diameter of slightly less than 9.5mm, including thickness of the original paint from suplex. With weight of the car (engine and box fitted) on the springs they are compressed to 7.5 inch for the front springs.

[danny_nelson]

Re: Cabrio Front Suspension Coilover Spring Broken

Hi Mike, I asked Mark Matthews this same question, and he advised 250/300 lbs for front on the Cabrio.I do not think there was any consideration give to the V8 as weight is pretty close to a Ford four cylinder.

[dogoncrazy]

Re: Cabrio Front Suspension Coilover Spring Broken

Mike
If my calculations are correct then your springs are 190lbs give or take a pound or two. Calculation is based on .385 wire diameter, 9 free coils and outer diameter of 3.02[ 2.25 +.385 +.385]

[mike woodley]

Re: Cabrio Front Suspension Coilover Spring Broken

Mark, Danny and Alan,
Thank you very much for your advice. Will try the bathroom scale test just out of interest.
Regards Mike.

[mike woodley]

Re: Cabrio Front Suspension Coilover Spring Broken

An update on the spring saga.
Contacted Mark at Marlin and he said that they started production with a spring rate around 180lb, and finished production at 300lb spring rate. He could not tell me what spring rate i had been supplied with. Contacted AVO and they advised sending my good spring to them for testing. The spring i sent was 200lb. Decided to increase the poundage to 250lb. Recieved my springs very quickly from AVO. They are now fitted and adjusted for correct road clearance. The car handles even better on the slightly firmer springs. The car is such a pleasure to drive, i might have got my bus pass but it turns me into a born again teenager!
Thanks once again for all the advice guys.