Unfortunately, after removing the oil pan I found the two thrust
washers. They were worn differently indicating that the rear one had
been install backward. The rear bearing cap was severely worn, the
journal of the crank was smooth and highly polished. The thrust
flange on the crank was worn, but looked repairable. I put photos of
the affected parts on my website at:
http://pages.prodigy.net/mikeross/TW.html . At the bottom of the
first page are links to two others. The consensus appears that I need
a new block, but can reuse the crank. I'm going to get a spare
engine from Ted Schumacher for the block for around $250.
I got allot of good advise from list members, and thank you all.
Here was a step-by-step procedure for diagnosing the damage I got from
Dave Terrick.
> Hi Mike!
>
> Allow me to spend a minute explaining what I know about the GT's
> engines because I think it will help you...
>
> I too have experiences TW failure. The very first thing that
happens
> is the clutch goes "funny" - because all of a sudden the crank can
> move forward 1/4" - and therefore so does the clutch, etc. This is
> when the tw's fell out. If that is within a tank of gas or so you
> are likely OK on damage.
>
> I have a sneaky feeling that whoever did the rebuild followed the
> incorrect installation procedures - one "manual" describes it right
> then shows an incorrect photo !! Anyway, if done backwards what
> happens is the steel face of the tw rubs against the rotating crank
> instead of the babbitt face causing rapid wear on the thrust faces.
> Then they fall out, then there is metal on metal and the crank can
> float back and forward at high rpm's ... and this is when the damage
> gets done.
>
> You can self-evaluate this issue.
>
> 1. Remove the rear main bearing cap. Do this while #1 and #6 are
near
> TDC for a better view.
> 2. Examine the bearing. It should look all "matt grey". If not,
> don't worry yet. If you see "shiny" spots or a worn "streak" near
the
> centre look next at the crank journal.
> 3. Examine the crank journal. Run your fingernail over the bearing
> surface. If you can feel any ridges with your nail, then you have a
> crank that was NOT reground ... and should be. You could also pop
the
> lower bearing shell out and look at the markings on the back - there
> will be a part # and brand. Vandervell (VP) is the best you will
find
> and is indicative of good parts all round (hard to get). The number
> may end in -010, -020, or -030 indicating an undersize ground crank.
> New bearings and less than -020 means the crank was redone and you
can
> likely proceed. No undersize markings and grooves means you should
do
> the crank anyway. -030 means some damage had been done previously
and
> you should contemplate a new crank anyway. :(
> 4. So far so good? Stop and have a beverage.
> 5. HERE IS THE CRITICAL BIT. to the rear of the journal is the
> thrust flange that will likely be damaged. This is likely the tw
that
> was installed backwards. Test it for grooves the same way as you
did
> the bearing surface. Small grooves here are less critical.
HOWEVER,
> when the tw drops, the spinning crank grinds against the bearing cap
> you removed and damage is done quickly. Not only this, but as the
> crank also grinds against the TOP half of the main journal (the cast
> bit of the crank webbing), this is why a bad tw condition can ruin a
> block. you can have the crank "spray welded" to save it, but a
ground
> down main web is asking for trouble! I've seen people do all kinds
of
> stuff to save blocks but they are almost all temporary solutions -
and
> then someone else winds up owning the problem - "DPO?"
>
> That's it, that's all to the inspection. Oversized tw's can be
bought
> up to + .030 (each) meaning you can have 0.060" of wear and still be
> "OK". They come in .002, .005, .010, .015, and .030. Presuming you
> go ahead, I'd suggest getting a standard size pair, .005, and .015.
> You can reuse the non-worn tw.
>
> Here is the re-assembly procedure:
>
> 1. Fit the standard tw's and replace the main cap - you do not need
> to torque it yet.
> 2. Using a dial indicator however it strikes you (be creative)
> measure the TOTAL fore-aft float of the crank. Spec is
.002-.008"....
> this is barely noticeable movement.
> 3. Aiming for closer to .002, remove a tw and replace with a
thicker
> one. You may chose to measure the thickness of each tw with a
> micrometer so you know what the net change will be. your "used" tw
> may be a thou or two down, a useful thing if the bearing face is
still
> good (do not re-use the ground down one).
> 4. Do final replacement of main bearing cap ensuring no dirt
> anywhere! Use loctite and a torque wrench to reset the bolts.
> 5. Congratulate yourself for a job well done, and noticing the
> problem in time.
>
> ***
>
> Now, while you're in there you can evaluate your timing problem.
>
> 1. The crank damper is a 2 piece affair - the inner and outer
bonded
> together by rubber. The inner is located by the key on the crank
and
> would only move if the key broke. the outer has the timing marks
and
> can move in a relative way if the bonding rubber has come adrift.
> 2. With the pan still off, you can pretty well determine where TDC
is
> (#1 and #6 rise and fall together, and they fire 360 degrees apart).
> Just get these cans to the top of their stroke.
> 3. Look at the timing marks. No matter WHAT they say, you are NOW
at
> TDC. I'd guess your accuracy to be within 1-3 degrees on the first
> try - a gross difference of 15 or more means the balancer has
perished
> and this is likely the cause of your timing problems.
> 4. Provided #3 passes, grab the fan and move cw/ccw. If the fan
> moves with the crank and has "slop" (easy, then hard, motion) of
more
> than a degree or two, you have a worn timing chain. What makes this
> worse is that this changes your CAMSHAFT timing AND your IGNITION
> timing (the ignition is timed off the camshaft, the cam is timed off
> the timing chain). No good can come from a worn chain.
>
> 1. Remove the pulley using either a gear puller or two pry bars
behind
> the inner part of the flange. Some force may be required.
> 2. Remove the timing cover making careful note (!!) of the
different
> length and location of all the cover bolts.
> 3. You should see a double row timing chain and gear. If not,
> whoever did the rebuild kept the original GT6 bits and should be
shot!
> The "correct" procedure is to get a TR6 crank and cam gear, as well
as
> a double row timing chain. Straight swap but by now I'd be tempted
to
> pull the whole thing to bits and do it over correctly.
>
> Trust yourself, Mike. These things are not really that hard to
> diagnose or repair if you are prepared to get a bit dirty and use
your
> head a bit. Please let me know how this has worked out for you.
>
> Dave Terrick
Thanks to all,
Mike http://pages.prodigy.net/mikeross
'63 Spitfire
'66 Spitfire
'68 Spitfire (donor body tub for GT6 convertible)
'69 GT6+ (donor chassis for GT6 convertible)
'70 GT6+
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