Cadillac Repair: reassembly 89 barrtz, auto theft siu investigation EUO expert, ignition forensics

Question
that 5/16 18=1 for steering shaft  on 89 barritz does not match thread pattern mor like 13 can you advise

Answer
Hello,

I believe you are trying Yonkers the upper shaft from walking up so you can instal the lock plate on a t&t column. I have rebuilt thousands of these.
Unless someone had used a tap on it changing the threads or who knows what and I have seen some real shoddy work on columns, you need a 5/16 18 x 1"Allen head cap screw. Push the shaft all the way down, tighten cap screw and put lock plate compressor on. Lock plate only fits one way as the c clip that holds the shaft together.
They columns were badtardized using metric and SAE. Of course the vehicles were like that.
Any way,1978 is when the shaft used a 13/16 head nut to hold the steering wheel. Before 1978 7/8 was used. However, the inside thread has always been the same. I stocked over 300 of these upper shafts, because when stolen, the steering wheel was forced, the shaft and lock plate would strip, also breaking the upper bowl because the lock pin would be force in the column. You would see a big crack on the top of the steering column. Tilts had issues too, but didn't have the side to side slop in the steering wheel.
As I said, I do not know why you are having trouble, and you may want to just run a tap down the shaft, the only size I have known it to be I 5/16 18 x 1 but it has to be an Allen head cap screw.
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