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BRITISH AUTOMOTIVE |
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www.mgbmga.com MGTD Articles |
Technical Information (MGB 14A)
FRONT SUSPENSION
CONSIDERATIONS
06/13/01
There are numerous front suspension modifications available for the MGB model, and we are aware that the average MGB owner's pocket book is the controlling factor when making a decision on any these suspension upgrades.Currently the trend is towards the coil-over arrangement, which requires crossmember modifications. We will keep you updated on the performance merits of these two suspension systems, as they become available.
One such manufactured front suspension assembly is shown below:
The other type of suspension conversion is the telescopic conversion by Ron Hopkinson which, we have recommended in the past. This conversion has no provisions for caster or camber adjustments.
Therefore, it would be advantageous to update to a fully adjustable coil-over front suspension system.
The aforementioned is shown in the illustration below:
The following information should be read in conjunction with technical articles MGB4 MGB13 MGB15 and MGB27.
For improved road handling performance, we recommend lowering the MGB ride height to the following specifications:
MGB and MGBGT (chrome bumper -> 74.5). Front 13.5" Rear 13.5".
MGB and MGBGT (rubber bumper 74.5 ->). Front 14.5" Rear 14.5".
Measurements to be taken from the center of the road wheel to the underside of the chrome strip.
Before replacing front or rear road springs measure the existing ride height. Installing new springs may not achieve the ride height you are looking for. We find that many times MGB owners replace road springs to rectify "leaning" problems. To their amazement some owners are mystified that their MGB is still "leaning" to one side or the other. We discuss this problem in depth within technical article MGB4.
Your MGB front suspension must be allowed to work.
The front suspension working distance is controlled by the bump stop/rebound buffer assembly. Lowering the front vehicle ride height will reduce this distance. Installing a shortened assembly can rectify premature contact with the bump stop. Your front suspension should have approximately 6" working distance. The rule of thumb is, for every 1/2" change in ride height, the bump stop clearance will increase or decrease by approximately 5/16".
If you are contemplating lowering your front suspension even further, without undertaking major modifications, be aware of the following:
Exaggerated lower a-arm angles, resulting in excessive negative camber path geometry. This will produce a "Twitchy" steering response especially during turn-in, which could lead to premature oversteer. Also, "Bump-Steer" will be a problem, especially when fitted in combination with negative camber lower control A-arms and OEM shock absorbers. Fitting revalved OEM shock absorbers will improve the situation somewhat.
The lower control A-arms should be as horizontal as possible. If you are going to lower the front suspension substantially you should consider installing lowered stub-axle assemblies, which will effectively lower your front suspension approximately 1" without changing the lower control A-arm installed angle. These assemblies can be purchased direct from the following:
"MG Unlimited" 414 529 3200 or e-mail MGLTD@yahoo.com
Excessive loads on tires, tie-rod ends and other steering/ suspension components should be avoided at all times.
FRONT SUSPENSION RECOMMENDATIONS
As of the time of writing, we believe that fitting of the following suspension components will contribute to improving the way your MGB vehicle handles.
| Qty | Part | Description |
| 2 | 264-395 | 1" Lower chrome bumper roadsters 3/4" Lower chrome bumper GTs |
| 2 | 264-385 | Coil Spring
480# 1" Lower rubber bumper roadsters 3/4" Lower rubber bumper GTs |
| 1 | 454-945 | 3/4" Sway Bar. |
| 2 | 280-915 | 3/4" Sway Bar rubber bush |
| 2 | ASP-75-2-S | 3/4" Sway Bar locators |
| 1 | 264-038 | Negative Camber LCA Set |
| 8 | 280-485 | Polyurethane LCA Bushings |
| 1 | 282-325 | Polyurethane Upper Bushing Set |
| 1 | 264-906 | Crossmember Polyurethane Pad Set |
| 1 | T045BB | Ron Hopkinson Front Suspension Kit |
Kit contains complete new upper mounting bracket assembly with Bilstein gas charged telescopic shock absorber. (Requires cross member modification). Available by direct purchase. Contact Ron Hopkinson MG Parts Center UK 011 44 1332 756 056.
If your budget does not allow you the opportunity to purchase the above kit, then we recommend the following substitute.
2 264-365 Rebuilt front Shock Absorbers
With
2 264-345 Heavy-Duty Shock Absorber Valve
Another alternative is to contact APPLE HYDRAULICS @ 1 800 882 7753 or visit their Web Site www.applehyraulics.com for information on their shock absorber rebuilding program.
Additional components that may be required are as follows:
1-2 264-325 Spring Shim- Raises ride height approx 3/16" Note: 2 Maximum per side.
1 8G621/NEG Nylatron Upper Offset Bushing (set) Changes camber + or - 1/2 deg.
HARDWARE INFORMATION
Numerous OEM front suspension, rear suspension and steering bolts were of the shouldered type; these special shouldered bolts are substituted, within the parts order form, with regular grade 8 yellow zinc plated bolts along with lockwashers and regular nuts. Slotted nuts are clear plated.
Replacement bolts may, or may not, have the correct length of shoulder as the OEM type. Similarly specific bolts supplied from within the Moss Motors catalog may, or may not, duplicate the OEM bolts.
All plated bolt and nut threads must be lightly coated with oil before assembly. Do not overtighten.
OEM SHOULDERED BOLT INFORMATION
| THREAD | A | L1 | L2 | L3 | |
| BUMP STOP MOUNT (LONG) | 5/16" SAE | .308" | .565" | .935" | 1.500" |
| STEERING SHAFT U/JOINT | 5/16" SAE | .308" | 1.125" | .500" | 1.625" |
| STEERING RACK MOUNTING | 5/16" SAE | .308" | 1.125" | 1.000" | 2.125" |
| PIVOT ARM ATTACHMENT | 3/8" SAE | .372" | .500" | .750" | 1.125" |
| SHOCK ABSORBER MOUNTING | 3/8" SAE | .372" | .313" | .687" | 1.000" |
| BRAKE DISC TO HUB | 3/8" SAE | .372" | .375" | .750" | 1.125" |
| SWAY BAR LINK ATTACHMENT | 7/16" SAE | .434" | 1.000" | .750" | 1.750" |
| STEERING ARM ATTACHMENT | 7/16" SAE | .434" | 1.188" | .812" | 2.000" |
| BRAKE CALIPER MOUNTING | 7/16" SAE | .434" | .750" | .562" | 1.312" |
| REAR S/ABS. MOUNT | 7/16" SAE | .434" | 2.250" | 1.250" | 3.500" |
| LEAF SPRING FRONT MOUNT | 7/16" SAE | .434" | 2.250" | .687" | 2.937" |
| REAR AXLE CHECK STRAP | 5/15" SAE | .308" | .937" | .937" | 1.875" |
OEM REGULAR THREADED BOLT INFORMATION
| THREAD | L3 | |
| SPRING PAN (INNER) | 5/16" SAE | 1.000" |
| SPRING PAN (OUTER) | 5/16" SAE | .875" |
| BRAKE DISC BACKPLATE | 5/16" SAE | .500" |
| SWAY BAR MOUNTING | 5/16" SAE | .625" |
| BUMP STOP MOUNT (SHORT) | 5/16" SAE | 750" |
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