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MG MGB GT V8 Factory Originals Technical - Steering racks: education needed, please.
|Can someone educate me on the MG steering racks one can use in a V8? Specifically,|
- how many turn lock-to-lock is a standard B rack? ... is this different for RB vs. CB cars?
- did a factory V8 use a different ratio?
- how many turns lock-to-lock is a C rack?
If possible, I would like something a little less quick than a standard B rack in my V8. They get going so fast that I find the standard rack a little too nervous.
|Hereís a quick history on the rack and pinion as it relates to the MGB V8.|
1. To clear the bottom of the motor the front cross member was spaced away from the body.
2. To clear the front of the motor the rack mountings lengthened, positioning the rack forward.
3. To clear the exhaust the steering column was shortened a couple of inches where it enters the engine bay.
4. To clear the exhaust a smaller u-joint was used to connect the pinion shaft to the steering column.
Each of the above required a longer pinion shaft and together the shaft is about six inches longer, but Iíve not measured it.
To simplify raising the newly designed rubber bumper to comply with American bumper height requirements, MG used the taller cross member developed for the V8 models. Changing the cross member required the other changes listed above as well as others.
To ease the steering effort required, the steering ratio was changed. Steering isnít as quick with the rubber bumper cars, but itís still better than most cars and itís much easer than the chrome bumper cars.
So the change in steering ratio came with the rubber bumpers for North America. Perhaps someone else can say when the changes occurred in the UK. I also donít remember the ratios, but they went from about 2.5 turns lock to lock, to 3 turns lock to lock.
Std B ratio from 62 to 76( introduction of smaller four spoke plastic steering wheel) is 2.9 turns lock to lock- this also includes factory V8s.
This means that the first two years of 1800 rubber bumber production shares its steering rack with the V8. CB std V8s usually have the continuous groove around the longer shaft in conjunction with the larger UJ. RB V8/1800 uses the smaller UJ in conjunction with the broad flat across the splines.
76 cars on use 3.5 turns lock to lock-long nose shaft with the broad flat groove.
If you want to make sure-you have to turn the rack shaft all the way to one lock-make a mark on the shaft and count the turns.
You will also come across the new racks which have been produced in recent years-to save money these are all 3.5 turns lock to lock in both cb/rb form. Earlier ones look similar to the OE Cam gears racks but are missing the embossed lettering and use plastic bushes I believe. The later moss racks are made in Argentina(!) and use a grub screw and lock nut to adjust the rack damper.
C ratio is I believe 3.5(I'm not an expert on Cs) and they use a unique arrangement on the pinion shaft with a rubber coupling disc.
Before you change the rack consider the steering wheel size and check that tyre pressures and suspension settings are correct.I think that the 2.9 is much nicer in feel. Your existing bulkhead arrangement/x member will also be a factor-how far do you want go with your modifiacations?
Hope this helps
This thread was discussed on 20/03/2001
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