26-27 brake drum with every driven plate hole cracked. every 26-27 drum I have ever seen is always cracked in this area. Its very thin and no surprise that it would be cracked. My guess is they were probably cracked when the cars were new. What are others experiences with these drums?
Jason I have had many 26 Transmission Brake Drum and don't ever remember finding any cracks. Maybe I just missed some. I will check some of my 26 Brake Drums today to see if they have any cracks.
Dave the ones I have seen always look good until they are blasted and cleaned in the parts washer. then the cracks are visible.
Jason years ago I was given a nice 26 Brake Drum and I had it on a work bench doing something to something else. I turned around and it rolled off the bench hit a cement floor and it had a lot of cracks. Another time I had a bunch of drums on a 6 or 7 high shelving. I don't remember how but it tipped over and again two drums had plenty of cracks (one was a 26 brake drum.
I have seen this also. I believe it is due to miss alignment on the 4th main. Causes the driven plate to "flex". Either the shaft in the driven plate gets loose or the drum cracks or crank breaks. Weakest link in the chain goes first. Dan
Has anyone had a drum to fail because of these cracks? I have taken them out of running engines like this and reused them. Have never had a problem.
That's the kind of thing you can't tell anybody you did, lest you be lampooned.
Hal I can take it. I've never saw a drum fail because of those cracks. I just can't see trashing them and buying new if not needed.
Has anyone had or heard of a drum failing because of these cracks at the bolt holes?
Has anyone ever turned the friction surface undersize and shrunk a steel band on? Dave in Bellingham,WA
Dave I think on the brake drum it would make it too weak. Since the brake drum holds the clutch pack it would make the lugs very weak. I'm still curious if anyone has had or heard of a drum failing because of these cracks at the bolt holes? Does anyone else just reuse these drums as I have?
I re-use them. No choice.
Kep have you ever had a problem with them? I think a lot of people reuse them. I also think a lot of people are even unaware that they are even cracked. Most of the ones that I have seen were not noticeable until blasted and cleaned in a washer.
Most are not as noticeable but these are the cracks I'm talking about.
I have noticed those cracks on the 26-27 drums. Its awful thin on that side. I to suspect that they were cracked when new or shortly after being in service.
(Message edited by jwalters on January 13, 2018)
Surely more people have noticed and dealt with this problem?
I'm curious if anyone has had or heard of a drum failing because of these cracks at the bolt holes? Does anyone else just reuse these brake drums?
I never heard of one failing due to the cracks. I guess I've been lucky but I've always been able to find brake drums crack free .
Thanks for your feedback Richard. Are the brake drums your referring to 26-27 drums? Anyone else have any thoughts on these drums?
I've noticed several 26-27 brake drums with those cracks. I've never experienced any problems in running them. My personal thought is they are caused by oil in the holes. If you tighten the bolts with too much oil in the hole, it has no where to go and actually "hydraulics" a crack in the weakest part, which is right where those cracks are. Just a thought. I'm sure there are others with a better explanation. Let's have fun out there all!!
William thank you for detailing your experience.
I was thinking of adding a high compression head. I'm curious if the cracked drum can handle the added torque?
I'm pretty sure there are lots of T's out there, running with those same cracks in them, whether the owners know about them or not. I believe they were caused by tightening, or maybe over tightening, the drive plate bolts. It's the kind of thing where, if you've got it apart, you'd kinda like to find a better one with no cracks, but if that isn't possible... I would not use one that had cracks that looked ugly and deep. Most that I have seen are very fine cracks.
As for wondering about the added torque of a high compression head, that's not important. Worry about the torque that goes through there when you use your brakes. Still, it's most likely not a problem.
Thank you Jerry for your info/advice. I will be adding accessory rear brakes so that should help. I'm actually thinking of making some cast iron drums and using the parking brake as a service brake. Any thoughts on that idea?
I assume you mean cast iron drums for the rear wheels? That would probably work well. However, Rocky Mountain brakes seem to work well, though not as well in reverse, as may be aware.