Crankshaft questions..
- Thread starter ZoomZoomZoom
- Start date
ZoomZoomZoom;1723937 said:
Do they say why? Seems kind of a silky thing to say. People have been using them for 20+ years with no problems.
It's lighter to so it will rev faster and will be just as smooth if you counter balance it.
1 is lighter and the other is heavier and counter balanced. Both have the same stroke and do the same job.
Less rotating mass revs faster.
Ij used both in the same motor and iirc the 6m crank held up better. Of course both were lightened counter balanced and knife edged and were revved to 8300+ rpm.
Less rotating mass revs faster.
Ij used both in the same motor and iirc the 6m crank held up better. Of course both were lightened counter balanced and knife edged and were revved to 8300+ rpm.
hvyman;1724299 said:
They were ALL revved to 8300 in the standard configuration, only the 7M got lightened and knife edged for the final 7M build.
6M
7M
Lightened 7M
6m is lighter. 7m is 7lbs heavier and is better balanced.
Its a toss up in stock form. You want the engine to rev faster or rev smoother.
Its a toss up in stock form. You want the engine to rev faster or rev smoother.
hvyman;1724027 said:
The neck was damaged by the harmonic balancer. It unevenly wore the material on the neck. My shop feels that removing further material to "fix" it would be detrimental. I have already bought a new balancer and pulley (OEM). Now I've learned that finding a 7m crank is very difficult. How hard is it to counter balance the 6m crank?
Any good machine shop could do it.
I was curious at why they say to use the 7m crank? There is no difference in journals or stroke both are interchangeable.
I was curious at why they say to use the 7m crank? There is no difference in journals or stroke both are interchangeable.
If the nose is screwed up from the harmonic ballancer coming loose, it isn't worth fixing, as it would have to be welded up, and recut.
A lot of work.
OK is your restoring a 1940 Messerschmitt ME109 crank, not worth doing on a Supra crank.
There are 7M (& 6M) cranks hiding everywhere.
I have tossed them before for minor things like a burnt rod journal.
I have a spare, and kind of want to keep it just in case, but for the right $$, I'll sell it.
I know I can come up with another.
But just look for people doing the 1J swap stupidity, they are probably going to trash the whole engine, and won't mind pulling the crank out and shipping it for a small fee.
I see them all the time in the for-sale sections, both 6 & 7M.
Look in some of the Cressida forums, as all 7M Cressidas came with the 7M crank.
A lot of work.
OK is your restoring a 1940 Messerschmitt ME109 crank, not worth doing on a Supra crank.
There are 7M (& 6M) cranks hiding everywhere.
I have tossed them before for minor things like a burnt rod journal.
I have a spare, and kind of want to keep it just in case, but for the right $$, I'll sell it.
I know I can come up with another.
But just look for people doing the 1J swap stupidity, they are probably going to trash the whole engine, and won't mind pulling the crank out and shipping it for a small fee.
I see them all the time in the for-sale sections, both 6 & 7M.
Look in some of the Cressida forums, as all 7M Cressidas came with the 7M crank.
IJ had the 7m crank lightened to 6m weight and balanced / knife edged. That is the overkill "ultimate" crank choice
if u arent going to do this i would go for a 6m crank and then balanced with the rotating assembly due to the lower weight of the 6m crank.
if u arent going to do this i would go for a 6m crank and then balanced with the rotating assembly due to the lower weight of the 6m crank.