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MG MGB Technical - Ride Height - Front end

After a lenghy overhaul and lowering ( to Chrome bumper height) of the front and rear end of my 77BGT, I am dissapointed to see the ride height at the front looks if anything higher than the Rubber bumper height I'd replaced.
I expected it to look at least 3" lower.
The new spring is 9.3 inches tall (free height)
the "old" spring of the RB model was 10.7 ??
See enclosed photo.
Anyone got any ideas ?
p.s yes, the engine is in situ

P Liles

Spring compression with weight is the only variable.The car was designed to have a minimum 5" clearance and the rolling radius of the wheel was 11.65" with front tyre pressure 18 - 24 psi.

from your picture, I would say that your rolling radius is less than designed.

We are conditioned to think that the cars were designed as we now see them - old and saggy !
R Walker

Having just gone through the saga of complete suspension change, including springs( and a few boo boos along the way) I am satisfied with the ride height and appearance. So I ask, are the new springs standard, or uprated? did you specify, when buying the new springs 'shorter'? Because my guess may be that you have standard rating and standard height.I understand you measured them, and the old seemed taller, was the new inevitably stiffer? Being new, they may need to settle. That was my thought before I embarked on my rebuild, I chose shorter slightly stiffer ones. As it happens, I will need to take care over tall man holes, but it looks cool. As we read on other threads, tighten all bushes once car on the ground, although this last was subject to debate. Guess what, if in doubt, strip down and do it again!( I had three goes before got it all right!) Mike
J.M. Doust

A quick addition to my last post,' I say tighten all bushes once on the ground'. It actually assumes you have tackled the bushes also, which actually you may not have! So it leaves us with just the springs. Have you located them properly? The should sit in their 'wells' but you could not have got both just on edge? Mike
J.M. Doust

I've found replacement front springs very variable, more so than rears which is what most people complain about, not even being the same free height as each other, let alone the *correct* free height. Ride height is a factor of spring free height plus hardness, I've not seen specs but I'd expect the hardness to have to go up if the free height is reduced to prevent continual bottoming, so it's a trade-off between the two.

How much stuff is left to fit i.e. how much weight is left to put back?

Have you driven it yet? Seems unlikely, and if that's the case you can expect it to settle quite a bit. Both my roadster and V8 came down nearly an inch after the first couple of miles, and more so over the next couple of thousand, since when they have stabilised.

PaulH Solihull

When I changed front springs for new ones, my car also sat rather high. I drove for about 20km before hitting a bump in the road that fixed it. It sounded like a grand piano had been dropped from a high building, and gave me quite a fright, but the ride height has been fine ever since,
dominic clancy

I was wondering why you would have to have stronger spring weight if you are removing the bumper I would have thought it just needs the same spring rate as a chrome car. Also with the spacers on the crossmember the engine sits higher off the road too.
Won't anything down to chrome height be the same poundage but below chrome height have to be uprated.

Ste
Ste Brown

Unless the bump and rebound stops are modified at the same time lowering the height of the car puts the damper arms significantly closer to the bump stops. The springs are shorter to achieve the lower ride height, but if they have the same deflection rate you will end up hitting the bump stops much more easily and often. Removing the weight of the bumpers does reduce that slightly, but the springs have to be shorter again to compensate for that. As I say I've not seen specs for the springs, but I'd be very surprised if they were not harder, and if they weren't again I'd be very surprised if they didn't bottom quite easily. There is a similar trade-off at the rear with damper drop-links, axle rebound straps and bump rubber pedestals.
PaulH Solihull

"you will end up hitting the bump stops much more easily and often"

.... and grounding the exhaust £££££££
R Walker

When I lowered the front of mine (78B de-bumpered) I used the shorter but stiffer springs. I also uprated the front ARB and put in stiffer shock valves. And I have the cut down bump stops. My A arms slope up to the outside of the car slightly but it has never seemed to cause an issue for me. I had the rears flattened a bit and actually went too far so now it does sit very low at the back. I did buy some supposedly lowered new rear spring and they were still far too high. What size tyre do you have there. It does look too small?
Simon Jansen

This thread was discussed between 07/11/2011 and 28/11/2011

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