| [ Total Views: 1427 | Total Replies: 19 | Thread Id: 40665 ] |
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 AdrianH
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| posted on June 17th, 2005 at 07:01 PM |
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Cracked Cranks
Big assumption, but at a guess the comment regarding this topic in the "what a beetle weighs" thread bears a resemblance to a comment on this thread
CB stroker
Cranks
The good seem to outweigh the bad as far as experience goes ??
[Edited on 17/6/2005 by AdrianH]
[Edited on 17/6/2005 by AdrianH]
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HGFS
A.k.a.: Greg
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| posted on June 18th, 2005 at 12:50 AM |
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The way I read it the feedback's mainly good. With a decent sales volume of anything you will always hear good & bad stories. The red beetle on
the cover of Ultra VW a couple of months back has been running a CB 82 for quite a while with no dramas at all.
Heaps of people buy Commodores but Ive had heaps of trouble with mine (company car 2 yrs old). I'm sure there must be some out there that tend to
work or they wouldnt sell at all.
Of course Berg cranks are meant to be close to the best but at $1200 US vs $280 US for CB they'd wanna be heaps better.
1954 Oval long term project going nowhere
1958 Beetle drag car project
1959 Beetle project I need to sell one day
1969 Squareback
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shiftyvw
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| posted on June 18th, 2005 at 07:48 AM |
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Also who here is running or has run a crank that they know is cracked in their car? |
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AdrianH
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| posted on June 18th, 2005 at 10:17 AM |
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Im running an 82mm CB crank, journals measured up fine, and its straight. Using their H beam rods and crank, I ended up with a bit more side clearance
(.017") than I would like, but no issues with it at all.
Not being negative about it, just noticed that KDF lad 's post in that thread came from NSW.
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HGFS
A.k.a.: Greg
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| posted on June 18th, 2005 at 10:18 PM |
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Hey Adrian, I'm planning on running that crank too. Did you go with VW or Chev journal?? Did you have to clearance the cam? Some of the guys in the
US reckon the gears don't fit as well with these cranks vs OG cranks, how did you go with that??
Thanks, Greg
1954 Oval long term project going nowhere
1958 Beetle drag car project
1959 Beetle project I need to sell one day
1969 Squareback
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Turbo54
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| posted on June 19th, 2005 at 12:45 PM |
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Greg, I am running this crank on my turbo engine and have had nothing but positive feed back regarding it. Good bang for bucks. I have used VW journal
and had no clearance problems. Let me know when your going to buy one, i'll put you onto someone.
T54
C'mon kids gather round,
there's a new sensation hitting town,
It's moving straight, low to the ground,
it'll pick you up when your feeling down.
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AdrianH
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| posted on June 19th, 2005 at 03:41 PM |
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Greg, with VW journals and the H beams I had to clearance the cam in a couple of spots, nothing major maybe 2mm.
The CB straight cut gears are tight, when I measured the crank against a stock one in the gear area it was on the money, the ID of those gears is
marginally tight. The last two sets have been the same, on a 74 and 82 cranks. The 74 was a welded stocker.
I also managed to get a set of buckpack gears that were .040" to big in diameter ?? Crank and cam wouldnt seat in the case...
Put the crank in the freezer, heat the gear on a hotplate and it drops on.
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HGFS
A.k.a.: Greg
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| posted on June 20th, 2005 at 12:01 AM |
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Thanks for the info guys, will still be a few months T54 before I buy it - will talk to you about it. I'll clear out the freezer in the meantime
1954 Oval long term project going nowhere
1958 Beetle drag car project
1959 Beetle project I need to sell one day
1969 Squareback
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dangerous
A.k.a.: Dave Butler Muffin Man
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| posted on June 20th, 2005 at 09:06 PM |
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Most of the steel crankshafts available now days can be
made better by nitriding and regrinding to .25 to form a
better radius in the corners of the journals.
The correct nitriding increases the fatigue life and improves wear quality.
Too much side clearance is rarely a problem...afterall,the oil
can only escape as fast as the journal oil clearance will allow
which is typically around 2 thou.
Ultimately when you have your crank reground you can get
your mounted bearings measured and the crank ground to
suit the exact clearance that you want, to eliminate
tolerance stack-up in your parts.
Berg cranks are nice but dont have a fillet radius any bigger
than the other half decent brands. They have a good finished
product appearance and you can get a berg sticker.
I have seen every brand of crankshaft crack or break and it
was usually due to poor tuning, lack of oil supply,or oil
contamination.
| Quote: | Originally
posted by westi
That's mad Alan.
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Craig Paton
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| posted on June 22nd, 2005 at 07:27 AM |
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Dave
If you were to buy a crank nowdays, what brand would you go for given that you've seen many brands and varying problems?
Maybe you should get into manufacturing since you built your own billet crank!
And which crank or cranks would you stay away from?
Craig
[Edited on 21/6/2005 by Craig Paton] |
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dangerous
A.k.a.: Dave Butler Muffin Man
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| posted on June 22nd, 2005 at 08:08 PM |
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Hmmm...good question Craig.
The only cranks I would stay away from are the cast ones.
I dont think I have ever seen one that wasn't cracked.
But then I suppose if it was a low power, low rpm,
low compression engine it may last for a while.
Those brand new VW engines you can buy have a cast crank
and fit the above criteria but have maximum journal
overlap and have rolled radii which improve the cast
material's fatigue life.
As for the steel cranks, my opinion may change on this, but
as long as there is enough material so that a regrind can
make at least a 2mm radius, most would be OK with a nitride job. We buy the Scat semi-finished cranks and finish them here, but I personally like the
Bugpack with the large type 4
centre and the flange, which comes nitrided.
Unfortunately most cranks now come in Chev journal, which
is good for clearance in the case, but not as strong as VW journal given the same stroke....there is just so much to talk
about in this area that I'll have to do a few posts over time.
Also if you use the rods with the .375" bolts they need more
clearancing than those with the .313" bolts....which should,
by the way, only be ARP 2000 material (or better) if you use
the smaller ones.
The 84mm berg crank and carrillos that you have, Craig, in
Porshe rod journal willcause you no trouble. Just have the bolts checked or replaced.It is a shame the Berg crank
doesn't come with a flange.
As for welded cranks, they are OK too provided they are
tested crackfree and nitrided, even from new. Just remember
that the longer the stroke, and the smaller the journals, the
weeker it will be. Unlike Bergs, I like the way the "full circle"
type cranks add strength to the long web...as long as the
welding is done properly. Take a look at a WBX web!
So until next time, my favourite crank would have large
mains, a flange, and large radii...even if the bearings need
to be chamfered to clear, and be nitrided. Oh yeah,always
cracktest, even new cranks.
| Quote: | Originally
posted by westi
That's mad Alan.
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Dasdubber
A.k.a.: Alan Agyik
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| posted on June 22nd, 2005 at 10:09 PM |
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Great info Dave, thanks for taking the time to post to inform everyone else of your experiences.
Same for everyone else of course.
I hate when people mouth off without any first hand experience so it is a nice change - I'm learning a lot!
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Keith Haeusler
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| posted on June 23rd, 2005 at 08:07 AM |
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Dave,
I have a couple of new scat flanged cranks here. In your opinion should i have them ground for a larger fillet before i use them.
They both have all type 4 mains, 2" bigends. I`d hate to have one fail on me. Also, are you aware of any thrust main bearing out there
that is suitable so i dont have to cut the tunnel and use type 4 mains.
I have a set of some BMW mains, they will fit the 2 and 3 main ( same as berg centremain adapter ). The thrust is close but no cigar. It`s
too wide in the saddle area. I was thinking maybe something similar to the wbx set up?.
Thanks, Keith.
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Turbo54
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| posted on June 23rd, 2005 at 10:23 AM |
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Hi Dave,
You didn't mention anything about CB stuff, Have you not used it or don't like it or it's good?
T54
C'mon kids gather round,
there's a new sensation hitting town,
It's moving straight, low to the ground,
it'll pick you up when your feeling down.
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Craig Paton
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| posted on June 23rd, 2005 at 02:21 PM |
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Very good read Dave! I have to agree with Dasdubber!
Already had my bolts checked and they have come up excellent! |
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dangerous
A.k.a.: Dave Butler Muffin Man
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| posted on June 24th, 2005 at 09:30 PM |
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Alan and Craig, thanks for the kind words.
Keith, those big main type Scat cranks are pretty good out of
the box and I wouldn't get it reground unless your oil
clearance was unaceptable...which is dependant on the
rod and case tunnel that you end up using.
Also if you chose to regrind you will have to re-nitride. But
you may want to find a good machinist first because some
can make the size correct but grind away the radii or form
one that is worse than what was there. In general, the Scat
cranks that you have represent the best of the shelf crank
with a flange that you can buy. As I said above, the next rung up would be to buy it semi finished and finish it locally to
improve all aspects, but it will end up costing twice as much.
As for the thrust bearing, I believe a toyota thrust, which is separate, can be used in conjunction with your BMW brgs but
I haven't checked this myself. You would have to check
whether the case is thick enough or can be machined to have the correct end float on assembly, and slotted to match
the anti-rotation tang on the thrust brg. This can be done
when you open the case for the big oil seal.
As for the CB stuff, I like the race rods, but only with the bolt upgrade,and their latest cranks seem ok, but can be improved
by using threaded plugs in the oil gallerys (how on earth can you clean out the passages?...yeah even if it is new!)
In the past their radii were pretty crappy so a pregrind,nitride
and finish grind to suit your mounted bearings is going to make
it much better.
The Bugpack,empi,and some other chinese cranks all have
their good and bad points, but can usually be improved
by the above operations...although some of these are a bit
lacking in material thickness compared to the Scat and Berg
cranks.
More latter.....
| Quote: | Originally
posted by westi
That's mad Alan.
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dangerous
A.k.a.: Dave Butler Muffin Man
23 Windows of Awesome
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| posted on June 24th, 2005 at 09:44 PM |
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Some of the Chinese cranks have an under cut radius that
is done on a lathe to make grinding easyer, which is bogus
unless you can have it rolled. I would probably avoid this
crank, but I like the forging and nitriding will make it better.
I believe the bugpack,empi,and some other china cranks all
use the same forging which is almost identical to the old
okrasa...even the way the oil holes are drilled...but the
finished product is not as nice.
I heard that Revmaster has always made the Bugpack cranks
(and their own) from those china forgings.
I may be wrong....have a look yourself if you get a chance.
| Quote: | Originally
posted by westi
That's mad Alan.
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dangerous
A.k.a.: Dave Butler Muffin Man
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| posted on June 28th, 2005 at 08:42 PM |
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Radii
Most cranks crack in either the radii or in the journal surface.
The journal surface cracks are usually heat stress from lack
of oil.
The radii cracks are from flexing, bending or twisting.
The radii help to strengthen the crank in these critical
areas, sort of like a gusset.
If there is no radius, or one that is poorly formed, the
cracks will begin sooner and travel faster than if there was
a smooth and consistent one.
Having a larger radius is like adding strength as would a
larger journal, but given the choice, a smaller journal with
a nice radius is probably better than a large journal with no
radius...particularly with the size and design limitations of the VW three main crankshaft.
That said, all crankshafts flex in operation and have to be
made from materials that can, with heat treatment, have
an acceptable fatigue life. VWs with 3 or more times the
original power output are always going to struggle in the
life span department.
| Quote: | Originally
posted by westi
That's mad Alan.
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dangerous
A.k.a.: Dave Butler Muffin Man
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| posted on June 28th, 2005 at 08:59 PM |
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5/16 rod bolts
Most people will get acceptable performance from the
8740 bolts.
My preference is to use the ARP 2000 material as a
minimum when using the small fasteners. As RPM limits are
raised, or piston weights increased, the loads on those
fasteners may exceed their design criteria. Stroke is a
major factor in the loads applied to the rod bolts during operation.
Carrillo use a bolt which exceed the strength of the
ARP2000 bolt because at 5/16 diameter they feel they
need to be of better quality.Last set cost nearly $500!
They use SPS brand, but ARP make some really good
replacements of equal strength called L19 and some other
materials too. Some other people may like to confirm or
deny this info.
| Quote: | Originally
posted by westi
That's mad Alan.
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dragvw2180
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| posted on May 31st, 2006 at 10:52 PM |
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ARP has a new rod bolt out,is right there with the carillo replacement bolts for strength,cost me 194.14usd from Summit Racing,including shipping to
North Carolina.Part# is 625+ 300-6708,this the set of 8.These bolts are good for 260,000 psi
[ Edited on 1-6-2006 by dragvw2180 ]
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