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Drilling bellhousing for earlier narrow trans bolt pattern

August 10 2017 at 6:59 PM
Homers65  (Login farmallmta)
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My '65 Galaxie FE manual transmission bellhousing is a C5AA-6394-A. Some of these are dual pattern drilled for both the early narrow transmission-to-bellhousing bolt pattern and the later wide pattern. Mine is drilled for only the later wide pattern, complete with thick bosses where the wide pattern holes are drilled and tapped. There is plenty of meat for the transmission bolts to grab onto. The narrow pattern holes in 6394-A bellhousings that have been drilled for both patterns do not have the extra material bosses in the narrow pattern holes while the wide pattern holes nearby do. The difference in the bosses for wide vs narrow pattern can be seen here:https://davids4speeds.com/product/1965-67-ford-galaxie-toploader-cast-iron-bellhousing-390-427-428-fe-c5aa-6394/

So in theory, the narrow pattern trans can be bolted to the narrow pattern holes, but I'm puzzled about how strong the connection is since there's actually not many threads in the bellhousing for the bolts.

I need to bolt a narrow pattern T-85C-OD transmission to my bellhousing with the wide pattern-only holes. Of course I can locate, drill and tap threads in the bellhousing so I can bolt up my T-85C, but is the bellhousing really strong enough without actual bosses?

Alternatively, I could change out the T-85C case with a T-85N case that has the wide pattern to allow bolting to the existing threaded bosses. I do have the N case, so it can be done, but drilling and tapping for the C case would be a bit easier and faster.

Anybody have experience bolting a narrow pattern tranny up to the dual drilled 6394-A bells? Would there be enough strength even if bosses aren't there? Thanks for your assistance!

 
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Tom P
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Re: Drilling bellhousing for earlier narrow trans bolt pattern

August 10 2017, 9:43 PM 

If the bosses are like the bell shown in those pictures it is plenty of material. I have seen transmissions adapted only going through a thin layer with washers and nuts on the inside of the bellhousing.

Also check the center hole diameter, that changed around 64-65.

 
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BattlestarGalactic
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Yes, bell pilot hole is different...

August 11 2017, 8:53 AM 

the narrow bolt box is like 1/8" smaller so you need to cut down the wide box retainer or re use the narrow bolt retainer.

I cut my wide pattern toploader to work in my '64 bellhousing in the wagon years ago.

LarryK
2006/2009 UMTR Points Champion

 
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Homers65
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I'd be putting the narrow bolt pattern case on a wide pattern bell

August 11 2017, 11:50 AM 

... so if I'm understanding you correctly, the narrow case input shaft retainer should fit into the wide-pattern without problem. But I'll double check that if I stick with the narrow pattern trans case. Thanks for the tip.

 
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BattlestarGalactic
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It will be sloppy...

August 11 2017, 9:23 PM 

you will need a wide pattern retainer to make it fit properly. That 1/8" smaller diameter will not register the transmission correctly.

LarryK
2006/2009 UMTR Points Champion

 
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RodC
(Login MT63AFX)
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I would swap trans cases thinking the "N" case.....

August 11 2017, 1:23 AM 

.....would be stronger than the "C" case. Drilling the BH for the "C" case won't necessarily weaken it but keeps it's integrity as designed by using the "N", jmo, RodC.
Mickey Thompson's 63 1/2 #997 S/S Hi-Rise 427 Lgt/Wgt Galaxie,
1957 C-600 Cab-over carhauler w/390-4V, 2-speed rear-end
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Homers65
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Thanks, Tom and RodC!

August 11 2017, 5:20 AM 

I'm thinking I'll go ahead and change the C-case out for the N-case. That way everything will look factory correct for the '65 Galaxie and the bellhousing won't be molested.

I appreciate your thoughts!

 
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Larry H
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Re: Early T-85 tranny in C5 bell housing.

August 11 2017, 12:39 PM 

If the T 85N case has a front bearing retainer with it, that's the retainer you need to use. Either way you go, you need to find a 65 or later BW front bearing retainer for your application. I think changing the tranny case makes the most sense.

 
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