Vintage Mustang Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
4,092 Posts
Discussion Starter #1
Finally got around to tearing apart my 302.
Everything looked good, the bearing etc, until I checked the thrust bearing.
The crank can move a whole bunch forward/backward. I used some feeler gauges and found .029" play! I believe its supposed to be .004-.008"???
I realize that measurement tolerences are not as important when the motor is coming apart, but doesn't that seem excessive? Might I have killed a crank? The motor was running fine when I tore it apart. Just wanted to redetail the engine bay and find a bit more power via new cam shaft and higher compression.

If I have to get another crank, I think I have no other option than to stroke it...
 

·
Registered
Joined
·
19,955 Posts
End thrust wear is greater on stick stift car then automatics from all of the thrust from when you push on the clutch. You may have a heavy clutch and therefore are exerting greater pressure, wearing out the endthrust bearing like that. I'll bet if you put in a new bearing for the heck of it, you'd find everything ok.
 
G

·
Guest
Joined
·
0 Posts
I'm sure it would be a real tragedy if you did end up "having" to stroke it... /forums/images/icons/wink.gif
 

·
Registered
Joined
·
7,671 Posts
A stiff pressure plate and cranking the engine with the clutch in will kill thrust bearings. A situation with a big load on the thrust with no oil pressure!

Start the engine in neutral.
 

·
Registered
Joined
·
4,092 Posts
Discussion Starter #7
It is a stick shift car, but I always make sure its in neutral when I crank her over.
That's an interesting point though! Something to keep in mind for future reference.
 

·
Administrator
Joined
·
19,311 Posts
Endplay is controlled by one bearing. The bronze bearing usually wears long before the iron crank does. The odds are very good that new main bearings will put you back in spec. Check it very carefully when the engine is going back together. It's kinda uncommon, but sometimes cranks can be worn enough that the new bearings won't tighten it up enough. THEN your only choice is a new crank.
 

·
Registered
Joined
·
283 Posts
Any reputable machine shop with a crank welder and grinder can weld the thrust back up if it is shot. It should be a lot cheaper than getting a new crank, I think we charge $40. It will probably need to be turned anyway, those are notoriously hard on the mains anyway.
 
1 - 9 of 9 Posts
Top