Topbow measurement

Bretto · Post by **Bretto** » Sun Sep 01, 2013 7:34 am

I'm re-doing some topbows that have some bad bends and whatnot that I will cut out. I will be grafting in new tubing to replace these bad sections. I was hoping someone could measure either the outside or inside width, whatever is easier, right below 90* curves so I know how wide these need to end up being.
Thanks,
Brett

billybob · Post by **billybob** » Sun Sep 01, 2013 8:33 am

I too am interested in the measurements. I am wondering if it is possible to fabricate them at home. It would certainly be a lot cheaper. If anyone has any plans or drawings it would be greatly appreciated. Thanks.

Kendall · Post by **Kendall** » Sun Sep 01, 2013 9:45 am

55" inside measurement just below the bend.
Kendall

RICKG · Post by **RICKG** » Sun Sep 01, 2013 9:52 am

If memory serves, the folding section of the bows I gave you
was in good shape and the stationary portion is what was
cut and bent. Get me the width and overall ht at the folding section
when folded and i'll confirm it against my good set. We know that
both sections should fold flat against each other and be same folded
ht.

Kendall's 55" dim is confirmed..

Post by **wesk** » Sun Sep 01, 2013 9:53 am

Several years ago I posted five bow drawings on the G503 site and asked for measurements. I got several replies with measurements. However I cannot locate my copy of the three drawings. They were loaded on "My Pic Gallery.COM and were lost when the web site collapsed. Did anyone here copy them?

Here are the replies:

Could someone provide the measurements listed using the photos as a guide. Email me your answers. Please indicate weather your bows are original or reproduction, M38 or M38A1 and if repop do you know who produced them.

Drawing #1
A-
B-
C-
D-
E-
F-
G-
H-
I-
J-
K-
L-
M-

Drawing #2
A-
B-

Drawing #3
A-
B-
C-
D-
E-
F-

Drawing #4
A-
B-

Drawing #5
A-
B-

I have an NOS top bow manufactured in the late 50s if I remember correctly. Here are some dimensions.

Drawing #1
A-1"
B-1-1/4"
C-It's tough to locate the lower end of C since it's both tapered and curved there. C+E is 2-1/4"
D-
E-
F-2"
G-installed on Jeep at this time, can't measure
H-installed on Jeep at this time, can't measure
I-
J-installed on Jeep at this time, can't measure
K-installed on Jeep at this time, can't measure
L-
M-1-5/8"

Drawing #2
A-32-1/4"
B-installed on Jeep at this time, can't measure

Drawing #3
A-
B-
C-
D-1"
E-1-1/8"
F-1"

Drawing #4
A-57"
B-

Drawing #5
A-
B-
_________________
Bob W. Monticello, NY. 1952 CJ3A, 1952 M38, 1950 CJV-35/U

Let me know if any of these do not make sense or you need an explanation.

Original bows for 1953 M38A1

Here's what I measured (all in inches):

Dwg 1:

A - 1
B - 1.25
C - 1.75
D - 3
E - 0.5
F - 2
G - 5.5
H - 3
I - 0.25
J - 0.75
K - 0.5
L - 1.125
M - 1.625

Dwg 2:

A - 32.5
B - 39.5

I added the following:

C - 3 (Inside radius of bend in bow tubing at top of bows - same on both)
D - 25.75 (End of bow to ctr of hole for top bow rod on outboard side of short bow)
E - 0.375 (Top bow rod hole diameter)

Dwg 3:

A - 1.5
B - 1.5
C - Approx 1 - very hard to tell
D - 1
E - 1.25 (assume this was to edge of tube, not entire bracket length)
F - 1

Dwg 4:

A - 57
B - 39.5

Dwg 5:

A - 57
B - 32.5
_________________
Troy Davis
1953 USMC M38A1 (Work-in-progress)
Rebuild Blog: http://troy-m38a1.blogspot.com/

What are Measurements for the forward bow for the support rod attachment points for 1952 M38 with a repro bow? Thanks!

The distance Center of Rivet to center of Hole is 25-3/16" on a NOS set of bows. the hole should be as tight as possible. Use a drill press if possible in order to get the holes at right angles, it will lessen the chance of having the rods work out. The Rivet is also 2-13/16" above the edge of the bodyith the bows installed. I eyeballed horizontal, and it appeared the rod was a bit higher at the rear, the relation of the set of front and rear springs is also a factor.
_________________
Jeep Mechanic Joel Gopan

http://www.willysmjeeps.com/v2/modules. ... ht=top+bow

http://www.willysmjeeps.com/v2/modules. ... ht=top+bow

Bretto · Post by **Bretto** » Mon Sep 02, 2013 8:04 am

Thanks all.
Rick, you are correct that the it was the stationary bars were cut and shortened but both bars were a bit bent on the top sections causing them to be short in the overal width.
The couple measurements in Wes' post of 57", I would assume would be the outside width since the tubing is 1".
Am glad I asked because I was trying to square up the 90* bends then measure the distance between the straight sections. I was on getting 56 3/4" on the outside or 54 3/4" inside.

Another question I have is about some (6) holes in the bars. An I am thinking most are stock, but want to make sure. Is there supposed to be 2 (#1) smaller holes about 3/16" on the top on both bars, just before the radius on the drivers side? And on the just the folding bow, there are 4, about 1/4" holes, 2 (#3) on the sides about 6" from the top and 2 (#2) on the forward facing edge about 4" from the top. I am not to sure about the 2 forward facing holes but certain the side holes are for the side supporting rods. Can someone confirm these holes.

Bretto · Post by **Bretto** » Mon Sep 02, 2013 8:29 am

A side note, I was just looking at weebee's site and they make mention there were 2 designs for the side support rods. One that the rod would go thru the top bow bar using 2 holes, and use used a cotter pin to hold the rod on place. The other design used only one hole and the side supporting rod was bent beyond a 45* to lock it in.

RICKG · Post by **RICKG** » Mon Sep 02, 2013 9:03 am

I have one hole #1 centered on the outside rad on the pass side
folding bow, it is aprox 1/4" dia and appears stock, punched not
drilled. #3 is your 3/8 dia rod support hole, 25" centered from the
pivot point. #2 does not exist on my bows.

Bretto · Post by **Bretto** » Mon Sep 02, 2013 11:40 am

I rechecked and the #1 holes are on my drivers side. The #2 holes do not look factory but the #3 holes do

I am continually impressed of the quality of time passed, this time I noticed there is OD paint on the inside of the tubing. Who would do that nowadays?

4x4M38 · Post by **4x4M38** » Tue Aug 26, 2014 8:56 am

Is there a reason not to go ahead and drill through both sides of the front bow for the support rod?

The WeeBee drawing shows two designs for the support rods, based on the hole only in one side of the bow, or the hole going all the way through.

I would think the latter with cotter pin would be a more robust mount for the support rods.

Any negatives to going ahead and drilling through the other side?
Thanks,
Brian

Post by **wesk** » Tue Aug 26, 2014 9:04 am

Only that the second hole will weaken the tube.

Bretto · Post by **Bretto** » Tue Aug 26, 2014 9:53 am

I don't know why but I was never able to get the angled rod to stay in place. They kept wanting to pop out. I redid my rods with 90*s and drilled the holes all the way thru and cotter pinned them.

Post by **wesk** » Tue Aug 26, 2014 10:10 am

The bows must be strapped tightly towards the rear to retain the door top rods the old fashioned way. Usually your problem would be caused by the top bows have inadequate tension aft due top loose rear straps or the top being shrunk to tight not allowing the bows to constantly apply pressure aft.

Topbow measurement

Topbow measurement

top bow measurement

Top bow measurement