C65 SMT to MT selec...
 
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C65 SMT to MT selector shaft woes

(@marsrock7)
Honorable Member
I have recently acquired the 6 speed SMT Bryon Bailey had for sale. Supposedly it is the one from BusDriver's supercharged SMT build from long ago. Bryon had it converted to manual with a selector shaft he bought from someone who said it was built for this application. Bryon never did install the transmission so the parts provided were never actually tested in a car until I installed the transmission last week. (No fault of Bryon's, he's been a great help)
 
The provided selector shaft did allow me to engage all gears, once I switched to a manual trans detent ball on top of the selector shaft housing. The only issue was a ton of slop in the shifter, even when in gear... I could move the shift knob side to side well over an inch. I got curious and pulled it back out, and laid it next to the 6 speed conversion shaft that I had in my old C60. The c60 conversion shaft is about 3/4" longer than the one provided. It worked well enough in the C60 but I always had issues with the shifter "hanging up" when I pulled it out of reverse. Took a lot of jiggling to get back to neutral before selecting a forward gear.
 
I was able to get in touch with Dave from DDPR and he said I needed the original SMT bits from it's selector shaft, and to put them on the shaft I pulled out of my C60. Bryon was kind enough to mail me the SMT shaft he had pulled out of the transmission, and I've spent most of today trying different configurations with varying degrees of success. The slop is still present regardless... So it may be an issue of shifter base bushings, or something else in the cabin. Possibly the cables, but I sure hope not.
 
Everything else I have tried results in the "hangup" after getting out of reverse. Tried this with reverse block out and without. Only one that never did hangup was the assembled shaft provided with the transmission, which has considerably more shifter slop in the cabin than any other configuration. I am at a loss currently. I don't want to go back to having the hangup between reverse and first. The transmission itself feels to be in excellent condition, and no bearing noise whatsoever. I just can't seem to find a shift selector shaft assembly that works perfectly! 
 
If anyone has any ideas.... They would be greatly appreciated. 
 
Attached is a picture of the included shaft assembly, next to my C60 conversion shaft. The C60 is the longer one. 
IMG 20200519 172650~3
...and yes I know the rear spring seats are backwards on both of these when I took the pic. 
 
 
Thanks for reading...
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Topic starter Posted : May 25, 2020 6:18 pm
(@marsrock7)
Honorable Member

Fixed this. 

A couple of weeks ago I swapped the shifter base bushings. They helped with the slop a lot, but some was still present, and more if I used the shorter shaft as pictured above.

After lots of digging, I came across a post on AdChat (I think the one about converting a 6 speed with all OEM parts) that briefly mentioned a brass bushing in the selector shaft housing, and some aftermarket selector shafts were too short to stay in the bushing, so the bushing would need to be tapped further into the housing to make everything work nice.  Knowing this was gonna suck to do in the engine bay, I popped the freeze plug out of my old C60, which gave me a similar issue but "improved" over time, and got an idea with what I am working with.

IMG 20200606 133911~3

The bushing.... And my "improvement" to it when the selector shaft unseated/reseated itself.

IMG 20200606 132644~3

More evidence of "improvement"

Came up with a tool for the job...

signal 2020 06 13 165435~2

Then went on to remove my extremely difficult to install airbox, jack up the car, unbolt the SMT selector blockoff plate, chisel it free, remove the selector shaft seal that was in my way, and finally see the culprit.

IMG 20200613 155120~3

This was with the car in first. Work space wasn't too bad, but still not great. This job would've been much easier to complete *before* the trans was in the car. Tap tap tap....

IMG 20200613 160457~3

Proof the selector shaft falls out of the bushing when in reverse. Furiously jiggle back to first gear, tap tap tap...

IMG 20200613 160939~2

Ended up with the bushing flush to selector in first gear. Still occasionally hangs when I go for reverse. So I had to leave it in reverse (or pull the shaft, but I wanted it there as a reference) and gently tap until the shaft reseated in the bushing and I got the bushing to move another 1/4"...

IMG 20200613 161810~3

Ridiculously crappy final result shot, in reverse gear. 

I can now engage all gears smoothly with no hangups anywhere. The first shaft that was in this transmission didn't hangup and was extra sloppy because it was too short to even reach this bushing to begin with. Many self congratulations and celebratory beers were had. After years of attempts, this is the first time in my life I have successfully fixed a transmission issue with a hammer.

During my research I found a picture of the OEM Spyder 6 speed shaft near (but not right next too, that would be too convenient) a tape measure and by estimations it is ~27.5cm long. The shaft I had in hand was a mere 26.6cm long. (Insert joke here). Hate when that happens. 

I believe the slop became more evident to me switching from 5 to 6 speed because the gates are much narrower. Later I will be removing the selector shaft again to swap to a firmer set of springs, reinstalling the reverse blockout, and making sure I haven't nearly sent the bushing I moved out of its housing all together. 

Note, this isn't an issue related specifically to SMT anymore, but 6 speed conversion in general. 

Hopefully no one else runs into this issue, but if you do, I hope this helps.

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Topic starter Posted : June 18, 2020 9:10 pm
Uncle Mush and dev reacted
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