Master Brake Cylinder 1941 K7


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Rusty Driver
Rusty Driver

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Post Sat Feb 02, 2013 6:01 pm

Master Brake Cylinder 1941 K7

I plan to buy a 1941 K7 next month. It seems to be one of the very early maybe prewar K7 trucks. The current owner tried rebuilding the master brake cylinder years ago and never put it back together, the parts are in a box in the front seat. I was wondering if the early K7 brake cylinder was interchangeable with some of the later KB6-7 MB Cylinders? I was also wondering what the chance was that I could find a NOS MB Cylinder?

Can anyone point me in a direction that I might find the part I am looking for?

Rusty Driver
Rusty Driver

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Post Sat Feb 02, 2013 7:05 pm

Re: Master Brake Cylinder 1941 K7

Ditto....

Yeah I need a master cylinder for my KB-7 also. The guy I bought my truck from rebuilt the master cylinder but he told me it was pitted badly (it leaks). The old IH site had a handy thread with a lot of useful info for parts sources and even part numbers. Amongst that thread was a NAPA part number for the KB-7 master cylinder, I had "writ" the number down but can't find it now. Do any of the administrators have access to that info from the old, Old IHC site??
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Post Sat Feb 02, 2013 7:55 pm

Re: Master Brake Cylinder 1941 K7

check with RockAuto: http://www.rockauto.com/catalog/x,carco ... Bfor%2BNTK
Think there is a discount code listed in the Vendors area for Rock Auto.
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Golden Jubilee
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Post Sat Feb 02, 2013 9:03 pm

Re: Master Brake Cylinder 1941 K7

zootownjeepguy wrote:Ditto....

Yeah I need a master cylinder for my KB-7 also. The guy I bought my truck from rebuilt the master cylinder but he told me it was pitted badly (it leaks). The old IH site had a handy thread with a lot of useful info for parts sources and even part numbers. Amongst that thread was a NAPA part number for the KB-7 master cylinder, I had "writ" the number down but can't find it now. Do any of the administrators have access to that info from the old, Old IHC site??


I have a new in the box master cylinder for KB-6, & 7, trade for a set of reproduction dash knobs?
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Rusty Driver
Rusty Driver

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Post Sat Feb 02, 2013 9:15 pm

Re: Master Brake Cylinder 1941 K7

I was just wondering, is a 1941 K7 interchangeable with a 1947 KB7???? It would be great if it was!

Golden Jubilee
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Post Sat Feb 02, 2013 9:30 pm

Re: Master Brake Cylinder 1941 K7

K vs KB is just trim level. A K-7 master should fit a KB-7. There were a few differances depending on GVW of the truck in question. I think all -7's used the same master.
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Golden Jubilee
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Post Sat Feb 02, 2013 10:24 pm

Re: Master Brake Cylinder 1941 K7

Both the IHC parts manual and Raybestos list two different master cylinders for these trucks,

a 3 hole mount raybestos # MC2657 , Wagner cross reference 3 hole mount# is MC2652

and a 4 hole mount raybestos is MC2842, Wagner 4 hole cross reference# is MC2842, same as raybestos

there has been question before about the 4 hole master, I've never seen one on a truck but they are listed by IHC and brake vendors.

yours is most likely a 3 hole mounting, K & KB use same.
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Golden Jubilee
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Post Sun Feb 03, 2013 2:41 am

Re: Master Brake Cylinder 1941 K7

According to the MT-53D parts manual the MC is listed by chassis number [aka SN].

MC assembly [For K7's only other models listed omitted]
Below Chas. # K7- 32583
48175H IHC
FE-661 Wagner
MC661 Raybestos & Wagner [current industry replacement PN]

Chas. # K7-32583 & up
56509R91 IHC
FE-2652 Wagner
MC2657 Raybestos & Wagner [current industry replacement PN]

For the '49 KB7 the Raybestos catalog lists the MC2657

Rockauto lists both PN's [Raybestos] with reasonable prices.


Link for MT-53D. See section 1205
https://www.box.com/s/otkihx6yoa/2/23417316/251328598/1

Raybestos brakes
http://www.raybestos.com/wps/portal/ray ... zAwMDAwMDA
12 yrs.exp. in IH dealer parts dept.
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If you don't have anything nice to say...say nothing.
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Rusty Driver
Rusty Driver

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Post Sun Feb 03, 2013 9:03 am

Re: Master Brake Cylinder 1941 K7

Well, I don't have the chassis number available yet, but I know it's a pre war K7 so I bet it has a low chassis number. Just wondering Scottso, does the MT-53D list the bore size of the master cylinder? From photo's I found on the net they look the same ( I know it does not mean much ), but I was wondering if one put out more volume than the other assuming they both bolted up?
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Golden Jubilee
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Post Sun Feb 03, 2013 9:48 pm

Re: Master Brake Cylinder 1941 K7

You're probably right about your truck being in the "below" category,it seem's logical anyway. Although in my years behind the parts counter I learned real fast that IH wasn't always very logical. :o
Look for the chassis # on the front of the left frame rail.

Now, I have researched a bit more and can tell you both MC's use the same body [casting] and have the same bore [1-1/2"] and same port sizes [2 @ 1/2" x 20 thread + 1 w/ 1/8 NPT].
They use different rebuild kits so the difference must be internal,either one has a residual check valve [RCV] & one doesn't. Could be both too [?]
Here's the kit PN's
For MC661
121401HB IHC
MK39 Raybestos
For MC2657
64837R91 IHC
MK135 Raybestos

I'll see if I can figure that out using the Hydro-vac's used and whether or not one or both has a RCV. A hydro-vac with a RCV will use a MC that does not have one and visa-versa.

I also found some "specs" for each MC
For MC661
http://www.wbaviation.com/nsndetail.cfm ... &pn=48175H

For MC2657
http://www.wbaviation.com/nsndetail.cfm ... &pn=MC2657
12 yrs.exp. in IH dealer parts dept.
Never argue with a fool...
If you don't have anything nice to say...say nothing.
If you don't learn something new everyday...you weren't paying attention.
THINK! Be sure brain is connected before mouth is in gear.
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