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BRITISH AUTOMOTIVE |
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www.mgbmga.com MGTD Articles |
Technical Information (MGB 4)
Composite Leaf Springs
Last Modified - 01/28/03
MGB Anticipated Ride Heights - MGB4(4)
During the development of British Automotive's composite leaf springs (over 10 years), we have installed and tested many of this type of spring. We have weighed countless vehicles and spent many hours trying to perfect this product. The final decision was to go with two spring rates 100# MGB Roadster and 135# MGBGT, available in both regular and low arch configurations. The composite springs that you purchase, when fitted to your vehicle will give an approximate rear ride height when measured from the center of the rear hub to the bottom edge of the rear fender molding. The measurement is entirely dependent upon the vehicle weight and weight distribution.
The latest test was carried out on a 1971 MGBGT which was independently
weighed (KERBSIDE) and, based upon this information, new ride heights
established for "chrome bumper" vehicles.
KERBSIDE
2306 lbs.
1156 LBS/1150
lbs.
50%-50%
| Spring Rate | Left Rear |
Right Rear |
100# (114#) RA 100# (98#) LA Difference (ride-ht.) __________________ |
13 9/16" 12 1/2" 1 1/16" ________ |
13 3/4" 12 3/4" 1" __________ |
135# (147#) RA 100# (139#) LA Difference (ride-ht.) |
14 1/8" 13 1/4" 7/8" |
14 1/4" 13 9/16" 11/16" |
From all of this information, it is possible to arrive at an approximate ride height for your vehicle, providing you know your vehicle's weight. For accuracy, we recommend that you weigh (KERBSIDE) your vehicle on an independent 4-wheel scale setup. For composite springs, subtract 30 lb. from your rear reading. Recommended ride height is 13 1/2 " (see "Suspension" article).
Testing for rubber bumper vehicles was conducted on a 1979 MGB Limited
Edition.
KERBSIDE
2320 lbs.
1160 lbs/1160
lbs.
50%-50%
| Spring Rate | Left Rear |
Right Rear |
100# (98#) LA |
14 7/8" |
15" |
To achieve the recommended ride height of 14 1/2" (see Suspension article), install 1/2" spacer blocks with the "Low Arch" spring as well as longer U-bolts.
We took the opportunity to measure the difference between "chrome bumper" and "rubber bumper" rear spring front mount and rear shackle mount eyes and we recorded a vertical increase of approximately 2."
For additional information select from one of the following categories:
MGB4...Composite Leaf Spring Overview
MGB4(1)...An Introduction to Composite Springs
MGB4(3)...MGB Vehicle Lean Problems
MGB4(6)...General Installation Instructions