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MG MGB Technical - Exhaust fouls axle !

O.K - rebuild on heritage CB roadster going well. Ride height at rear with new standard springs is around 15.75 inch. Biggest headache is that because of this the exhaust fouls the rear axle as the body is too high. Any clues? I have read the archive on ride height and some say the springs settle, but how to drive it without an exhaust !! Cheers,
Andrew

Have your local muffler shop route the exhaust properly. You can lower the whole thing or bend the pipes differently to gain additional clearance.
Steve Simmons

Andrew

You havent been supplied with rubber bumper rear springs and a chrome bumper exhaust have you?

where did you get the springs from and do they have a number painted on them.

This is mine with GT springs on and it still clears.

Steve

Ste Brown

15.75 sounds very high for a CB car at the rear. Where are you measuring from? I believe the 'standard' place is the center of the wheel to the bottom of the chrome trim strip.

Simon Jansen

Simon is right, and it should be around 14" to 14.5". There are some very dodgy springs around which are either way too hard or too arched and give a ridiculous posture, like a submissive monkey. Did you have any problem getting the rebound straps and rear shackles fastened? If so, and if the car was otherwise equipped with screen, engine, gearbox, prop-shaft etc. and ideally seats there should be more than enough weight there to compress the springs enough to get those fastened easily. With the car on its wheels is the bottom eye on the rear shackles facing forwards or rearwards? Should be rearwards, and the springs themselves should be nearly flat, and the rebound straps have a pronounced curve. Have a look at the photos and dimensions on http://www.mgb-stuff.org.uk/wn_suspensionframe.htm and click on 'Ride Height'.
Paul Hunt

Andrew
Is yur car complete --like,seats spare wheel battery etc If not they will probably give you enough clearance till your springs settle maybee. Willy
WilliamRevit

Thanks for the ideas - I think that rubber bumper springs is the most likely, they had BHH on them (before I painted them) and this relates to a GT or a rubber bumper car. I have contacted Watford MG (the suppliers) and asked them to replace them. Also the front springs now with engine weight on them seem too high ! 16.5 inches from bottom of chrome to centre of wheel. Guess I'll need to take those off too - annoying. I'll let you know what happens when I compare the part dimensions.
Andrew Walton

Incidentally - the rebound straps won't fit as the gap is too large !!!!!!
Andrew Walton

BHH is simply the part number prefix, there are various numbers following that according to spec and whether front or rear. As far as the rears go they are indeed for rubber bumper cars only, CB GTs used AHC 31 and roadsters AHH 7080 at the rear. At the front roadsters used AHH 6451 originally which were 9.9" free height, these were modified for 73 and later cars to give 10.2" free height part number BHH 1225.

However the difference between CB springs and RB springs is relatively small, the bulk of the difference in ride height between the two came from the spring mounting positions at the rear and the crossmember at the front.

Long-time manufacture British Springs went bust a while ago, and suppliers are running out of stocks and trying to find an alternative manufacturer. And that is going to need careful trial-fitting to get the specs right. America has long had problems with springs being too hard and/or arched, if UK suppliers are tempted to buy from them then we will get the same, and this seems to have been happening with some sources even before British Springs went bust. Not being anle to fasten the rebound straps on a fully fitted-out car is a sure sign of bad springs.

Whilst springs will settle on the first shake-down run, if they continue to settle after that then they have a crap temper and you will be dragging on the ground before long. Any supplier who tells you they will continue to settle is passing-off stuff they know to be rubbish.
Paul Hunt

This thread was discussed between 15/01/2009 and 23/01/2009

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