Direct Drum Help

#1
*DIRECT DRUM:
The direct drum must be within .030 of original diameter. Cannot be bent or heat deformed. DO NOT drill holes in band surface. This does nothing but add problems with band oil, the direct clutches slinging their lube out, and I have even seen them crack from the holes, and distort the actual drum itself.(Like a brake rotor) Weakens them immensly. All steels must slide freely in bore. In ring bore, no ring cavities can be present. One of the most common 2-3 flair symptom is , bore is ring grooved near bottom of drum using cast iron rings. Band surface must be PERFECTLY FLAT, no scores, especially with the use of the new band. ...

OK, I certainly appreciate the good advice here on the 200 4r. I am trying to abide by it , referring to it as I reassemble the trans...I could use some help, here. Am rebuilding a spare tranny for use in my T, and the direct drum is not "perfectly flat" without scores...So I went to the tranmission wholesale rebuilder with whom I've traded for like 15 years....no more direct drums...just a couple of refurbished (welded. turned/polished) ones...wrapping a band around them and measuring end gap (with my hundreths scale which i had in my pocket protector-bet you think I'm kidding-nope), my used scored drum was still .016 in dia larger than the ones they were trying to sell....I didn't bite....

So.....
1. Where can I get a new (or good servicable) drum?
2. What is original dia and I'll throw mine on my lathe and resurface it ......and I can see it it'll clean up at <.03 under.

Thanks,

J Nesbitt
 
#4
Thanks for the help.....I measured the one I was trying to replace and it measured 19.5 inches circumference or 6.207 OD. This was with an unverified mylar scale. It could be inaccurate. I'll drag out the big anvil mike and measure it more accurately tonight. I thought that this wouldn't be a hard question, but I didn't know the answer.

The direct drum is what the band is around, so the concern is the outside diameter/condition of the friction interface.

Thanks,

JN
 
#5
I see

I know what you are saying. I have a few used drums from cores that I pick up when I can. I bought a 12 in. caliper just to measure these. Of all that I have, the most of them measured 6.180 in. in dia (assuming my measurement is accurate). I have a local friend who turns them for me. You are correct, anything over .030 makes the band come too close to touching on the ends to suit me. Also effects the servo setting.
 

PaulRV6

Active Member
#6
Bruce @PTS

I just measured my drum OD which is in really good condition it seems w/o any ridges or grooves nut it measured 6.172" 1/2 way up.

What is the factory dim and tol?

Bruce, you know?

paul
 

Mike T

Well-Known Member
#7
Old thread but seems to be the only measurements posted. FWIW mine now measurers 6.168 after a resurface which seems to be in line with others.
 

bison

Moderator
Staff member
#9
*DIRECT DRUM:
The direct drum must be within .030 of original diameter. Cannot be bent or heat deformed. DO NOT drill holes in band surface. This does nothing but add problems with band oil, the direct clutches slinging their lube out, and I have even seen them crack from the holes, and distort the actual drum itself.(Like a brake rotor) Weakens them immensly. All steels must slide freely in bore. In ring bore, no ring cavities can be present. One of the most common 2-3 flair symptom is , bore is ring grooved near bottom of drum using cast iron rings. Band surface must be PERFECTLY FLAT, no scores, especially with the use of the new band. ...

OK, I certainly appreciate the good advice here on the 200 4r. I am trying to abide by it , referring to it as I reassemble the trans...I could use some help, here. Am rebuilding a spare tranny for use in my T, and the direct drum is not "perfectly flat" without scores...So I went to the tranmission wholesale rebuilder with whom I've traded for like 15 years....no more direct drums...just a couple of refurbished (welded. turned/polished) ones...wrapping a band around them and measuring end gap (with my hundreths scale which i had in my pocket protector-bet you think I'm kidding-nope), my used scored drum was still .016 in dia larger than the ones they were trying to sell....I didn't bite....

So.....
1. Where can I get a new (or good servicable) drum?
2. What is original dia and I'll throw mine on my lathe and resurface it ......and I can see it it'll clean up at
Thanks,

J Nesbitt
6.180-6.182” seems to be typical of a good stock one. I wouldn’t take off more than .010” of the diameter if it was a 9 sec trans. Most are shot these days


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bison

Moderator
Staff member
#10
Old thread but seems to be the only measurements posted. FWIW mine now measurers 6.168 after a resurface which seems to be in line with others.
That would be about the min I’d use in a high performance application


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Mike T

Well-Known Member
#11
Supply of good used drums are drying up bigtime.
Stopped by my friends transmission shop today assuming I'd be leaving with all sorts of spare parts. He said he's only did 3 2004r's in the last five years and doesn't have much in stock anymore.