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MG MGB GT V8 Factory Originals Technical - Steering Column Mount
|Those of you who have done a chrome bumper conversion using the double UJ column.|
Did you have to modify the lower steering column mount to lower the whole thing clear of the manifolds (tubular not RV8) or did you use the original and was it OK?
I am reading different opinions on this.
|Some change must be made. Car companies, particularly dirt-poor car companies such as MG donít change things for no reason. Still I tried all sorts of ways around it and it must be altered.|
What worked was replacing the í71 steering column with one from a wrecked í75. It bolts under the dash perfectly (at least for the North American cars). I also got the part of the firewall that the forward end of the column bolts to out of that í75 and grafted it to the í71. The problem at that point is that the old pinion shaft is too short and too high to reach the new location of the shorter steering column. The newer smaller U-joint is required and so is the entire rack and pinion system. Now the shaft will be too long and still be too high so it must be cut shorter and a groove cut for the U-joint bolt. To get the correct lower angle Glenn Towery alters the rack housing, but I already had the steel mounts from the cross member cut from a failed expieriment so I just re-welded them to the correct angle.
|I'm still confused!|
As a CB converter, do I just need the special column and pinion, which I have.
Or do I need a whole special rack as well?
|I used collapsable steering column, the shell was like that, no mods, I used shaft with two small uj, the shaft is very closely of the exhaust manifold lower bolt, I modify, slightly, the left engine bracket to the shell, but my car is LHD, I modify also the steering rack, with a short pinion built by my machinist. Thatís all.|
When the rubber bumper column is mounted under the dash of a chrome bumper car the steering wheel is in the same location. The forward end is short of the mounting location of the chrome bumper mounting location so it needs altered. Also the forward end of the column where the U-joint connects is closer to the driver. That leaves a gap of a few inches between the U-joint when connected to the shorter rubber bumper column and the U-joint end of the pinion shaft.
Some people do cut the pinion shaft near the rack housing and add a second U-joint there to bring the pinion shaft angle down and back to the new, more distant and smaller U-joint attached to the column, but its very crowded down there around the motor mount welded to the frame rail. The other solution is to replace the short rubber bumper pinion shaft with the longer pinion shaft from a rubber bumper car. Whether you can replace just the pinion shaft or have to replace the whole rack and pinion unit has been debated because at some point the steering ration changed so that some pinions will not mesh with some racks.
If you replace the whole rack and pinion unit and mount it to the original mounts on the cross member it will be too long and be pointed too high. Replacing the cross member would line it up, but has drawbacks. So the shaft that is long enough is too long and mush be shortened and must also be angled. As I said, Glenn Towery solves the angle by altering the mounting surface of the rack housing and sells these to converters. Because I had attempted to follow instructions of a bad design my cross member mounts had been cut anyway so I just got them so the rack housing tube was in the original location and set at the required angle and welded back on.
So that was the long answer on whether or not you have to change the rack. The shorter (but not short) answer is the chrome pinion shaft isnt long enough so would have to be replaced so its handy to get the complete rack and pinion unit from the same donor car as you source the column, U-joint and firewall panel. Trying to mesh a pinion shaft from a rubber bumper car with the rack from a chrome bumper car may not work because of a change of steering ratios. Its possible the change to the steering ratio happened at different times in different markets and its possible they do mesh, I didnt try it.
I hope that helps.
|Michel thanks for the photos, and George thanks for the detailed explanation.|
The custom pinion to which a lower UJ was fitted slipped right up into the CB steering rack no problems. I was worried the upper UJ might be a bit too close into the engine bay.
I may have been getting confused with my terms of reference. I assumed the pinion was part of the column, whereas it could also be the 'custom' part of the 'custom rack'. Having now fitted it to my standard CB rack and found it fits I suppose I could now say I have a custom rack.
Still, the manifolds are on order so the ultimate test is not far away.
This thread was discussed between 14/03/2006 and 15/03/2006
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