Jim, The quick and dirty solution, if there is enought meat on the end of
the crank to do so, is to countersink the pilot bushing to allow space for
the input shaft, or chamfer the end of the crank. sounds like you don't
need much, perhaps 1/8 inch. John
Jim Stuart wrote:
> Well, an update on what has become an interesting, if somewhat
> frustrating problem:
>
> Not satisfied with disassembly/ reassemble to eliminate the problem, I
> dug into it again this weekend. Boy am I tired of r & r'ing the clutch,
> flywheel, bell housing, tranny!
>
> This is what I have discovered- smarter ones on this list probably new
> the answer, I just didn't ask correctly. The engine I have is approx.
> 1994 4.2 L from a Land Rover, originally with a serpentine drive front
> cover. As such, it has a slightly different crank than the Buick/Olds
> that I am more familiar with. The rear of the crank has a tubular
> extension that holds the pilot bush. On the Rover, this extends approx.
> 3/4" beyond the flywheel mounting flange. On the Buick/Olds, the
> extension is 5/16". This is something I had not noticed until yesterday.
> It does not present any obvious problems, the flywheel & clutch assembly
> bolt up just fine. Apparently, some Rover engines have a spacer, solid
> chunk of steel, that slides over the end of the crank, spacing the
> flywheel further to the rear, so it looks like the end of the GM unit. I
> don't know when this is used, manual or automatic? or why. I assume it
> is to space the flex plate or flywheel to align with the starter drive.
>
> The transmission is a Chevy T-5, not a Rover, & the bell housing is a
> 3/4 speed Buick. The flywheel is an after market Buick/Rover replacement
> item, clutch is a Chevy S-10, 10.5".
>
> This extra 3/4" of crank length is my real problem. Everything bolts up
> just fine until you finally snug up the tranny. When this is done, the
> splined section of the tranny input shaft comes to rest on the end of
> the crank, forcing the crank forward in the engine, until it locks the
> engine due to the pressure against the thrust washers, or some other
> internal part. I could only see this by removing the clutch assembly and
> then installing the trans. As I tightened the trans to bell housing
> bolts, the input shaft became harder & harder to turn, until it stopped.
>
> To prove my observation, I installed 1, 1/2" flat washer on each bolt,
> between the tranny & bell housing. when tightened down, everything was
> free.
>
> Now, 2 questions. How much space is really required, how/where to space.
> Observation shows that the small end of the input shaft resides entirely
> within the pilot bearing. I do not see this as a problem. More of the
> shaft is supported by the bush than is normal, but is this bad? I am
> using a hydraulic throwout bearing that is adjustable for length, so the
> distance from the face of the tranny to the clutch (or flywheel) is not
> a problem. There are 2 obvious places to add a spacer, between the block
> & bell housing, or between the bell housing & tranny. There is plenty of
> space within the bell housing for the clutch, so no need to space here
> for that reason.
>
> I am not comfortable with just leaving washers between the tranny & bell
> housing, as it seems that it will put all the stress on the ears of the
> trans. Any contrary opinions are welcome, as this is the simplest
> solution. Alternately, anyone capable of providing a spacer, please let
> me know. This is the last item keeping the car off the road.
>
> As usual, I am counting upon the magic of this list for advice.
>
> Jim Stuart
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