Info needed: F60S LAAT Wheel Cylinder size

[Mark Towers]

Dear friends,

It’s time to replace the wheel cylinders on my 1944 F60s LAAT.

I have read a couple of contradictory posts stating that my vehicle model should have 1 1/2” cylinders front and rear, then another post stating that I should have 1 3/8” on the front and 1 1/2” on the rear.

Could anyone kindly advise which is correct.

Kind regards

Mark

[Jacques Reed]

Hi Mark,

This may point you in the right direction:

From 1943 Maintenance Manual:

"On models equipped with 4 7/8" steering ends:
The front brake drum dimensions are- Diameter 14", Width 2".
The rear brake drum dimensions are- Diameter 15", Width 3.5".

"On models equipped with 6" steering ends:
The front brake drum dimensions may be either 14" x 2" or 15" x 3.5"
Rear drum dimensions 15" x 3.5"

Logic would indicate that if the front drum dimensions are the same as the rear they would use the same size cylinders- 1 1/2" instead of the 1 3/8" used on the 14" x 2" drum.
I doubt if 1 3/8" cylinders would work with 3.5" wide brake drums. The distance from the centre of the pistons to the backing plates is less than with the 1 1/2" cylinders so they would not line up with the center of the brake shoes.

Will leave it to someone who has 15" x 3.5" drums on their 6" steering ends to confirm this.

As a matter of interest, what size are the front drums on your F60-S?

Cheers,

[Mark Towers]

Hi Jacques,

Thanks kindly for your helpful reply .... I’ve only taken one rear wheel
off at present but will get back to you once I’ve successfully removed and measured a front wheel.

The wheel cylinder I removed today looks in a terrible way ... infact it kept sticking last year and playing up so I’ve decided now to replace all cylinders and perhaps the Master cylinder (if I can source one?) .... I’ve checked the “modern part numbers” thread here on MLU but the number given for then Ford Master Cylinder dos’nt come to anything when I search companies

Kind regards,

Mark Towers

1944 F60s Laat
1942 40mm Bofors
1940 BSA M20
1942 Matchless G3L
1944 Mk5 BSA Roadster Bycle

[rob love]

The key number for the master cylinder seems to be MC4572. They are very reasonably priced here in North America.

[Grant Bowker]

According to "Ford Illustrated Army Parts Catalog 1940-1942" (S.E.-39-42 Reissued January 1942) the same "Cylinder front brake 1-3/8" diameter" were used on F15, F15A, F30, F60S F60L F60H and GT. This was part number 92Y 2192.
The listing then gives a separate listing for those vehicles using the 6" joint (F60S, F60L and GT) - part number C118Q 2192 - "Cylinder front brake 1.38" diameter". (interesting that they chose to use decimal notation: 1-3/8" is 1.375', rounded to 1.38')
In this publication, "Cylinder rear brake 1-1/2" diameter" 91T 2192 is listed for the same wide range of vehicles F15, F15A, F30, F60S F60L F60H and GT.

I don't have the individual parts listings for F60S or F60H to compare but the F15-01, F15A-01, F60L-01 and FGT-01 lists all match the above.

To compare to Chevrolet practice (who used Ford brake parts on the F15A up):
Parts lists 175 and 197 (wide range lists) only list the wheel cylinders for C8 and C15 (the ones with Chevrolet brakes).
Parts lists C15A-04, C30-03 lists front brake wheel cylinder part 92Y2192 (no size given),
Parts lists C60S-03, CGT-03 list 1-3/8 cylinder 92Y2192 for vehicles with 5" joint, 1-1/2" cylinder 91T2192 for vehicles with 6" joint (serials 184--28127 to 284--00003) and 1-3/8" cylinder C118Q2192 for vehicles with 6" joint (serials from 284--00003)
C60L-03 follows the same sequence but doesn't give the serial number breakdown.

From the above, it appears most 3 ton (maybe all Ford 3 ton) CMP used 1-3/8" front wheel cylinders.

A theory to explain larger wheel cylinders at the rear compared to the front might be that the trucks were designed for the loaded condition where the rear axle was more heavily loaded than the front so more braking was needed at the rear. The Chevrolet lists suggest there was a plan to standardize on one wheel cylinder for front and rear on the heavier vehicles with 6" joint and that it may have been less than a complete success (I'm guessing) so they reverted to different sizes front and rear.

[Tony Smith]

This issue arises often.

In this thread (HERE), Harry Moon confirms that the 6" fronts use a wheel cylinder that is the same dimensions as the large 1 1/12" rear, but only have a bore of 1 3/8". This "Special" cylinder (C118Q 2192) does not seem to be currently re-produced. All that are available are are the small front 1 3/8" cyl (Modern No W4571) for the 5" hub, and the large rear 1 1/2" cyl (Modern No W4511) used on all rear brakes.

You might consider using a W4511 rear on the front brakes, but you need a 1 3/8" cyl in the front to stop the front bakes locking up, however the W4571 although hydraulically correct size, is dimensionally too small for the width of the brake shoes. I think the bolting mount centres are also different too.

You need to start with the rear W4511, which is the correct size casting, but have it sleeved down to 1 3/8" bore. This reduction in bore size is probably beyond the size sleeve used by regular brake sleeving companies who do this work in brass or stainless steel. You might need to have the sleeving done in two steps, a coarse bushing to get closer to 1 3/8", then a a fine sleeve in brass or stainless to be the hydraulic finished bore. Assemble the cylinder with the 1 3/8" cups, pistons and spring from a W4571 rebuild kit (WK103), and the outer boots from the W4511.

[Grant Bowker]

Originally Posted by Tony Smith

This "Special" cylinder (C118Q 2192) does not seem to be currently re-produced. All that are available are are the small front 1 3/8" cyl (Modern No W4571) for the 5" hub, and the large rear 1 1/2" cyl (Modern No W4511) used on all rear brakes.

Interestingly, the C118Q2192 is not listed * (unique to CMP) in the parts book so it should have been an "off the shelf" commercial part. On the other hand, the C in the part number indicates Canadian, so there is probably no perceived market for reproductions (or not enough to justify starting to produce).
Google didn't give much help on the character string C118Q2192 (also tried with blank and dash after the Q), does anyone have any cross reference listing what vehicle(s)the part might have originally been used for?

[rob love]

Originally Posted by Grant Bowker

does anyone have any cross reference listing what vehicle(s)the part might have originally been used for?

I have the Chassis parts catalogue for Canadian Built passenger and truck models, 1941-1947. It does not list the C118Q2192 wheel cylinder at all.



I think I have a low cost solution at work....I'll have a look Monday and report. It does not involve anything as involved as sleeving.

[Mark Towers]

Gentlemen,

Thank you all very much for all your feedback and advice .... it clears things up considerably

Rob I look forward your update regarding a low cost solution

One has to try and keep ones marriage happy lol.

Kind regards

Mark

[rob love]

OK, so I remembered today to check this out. I know in the past I have used MLVW (M35CDN) wheel cylinders by changing the pucks in the cylinder, so today I compared those cylinders with the CMP cylinders I have in stock here at work. The bolt holes and line fitting are the same as the 1-1/2 wheel cylinder but they are 1-3/8 in diameter. They also seem to have the same center (from the backing plate) as the 1-1/2 inch cylinder.

I checked the old American NSN for the wheel cylinders and came up with a part number of WC4419. I checked NAPA and they list them under part number 4419 at $40 trade price. Or you can simply look up M35A2 wheel cylinders on ebay....lots of them available.

You will have to move your pucks across from the old wheel cylinders, as the M35 uses the little rods rather than the shoes resting directly on the pucks. As well, you will need the different boots. The part number for those are 5975.

Now it's very possible that somebody is making up the required combination of wheel cylinder and pucks that we need. But at least we know that the casting is available.

I'll be facing this challenge, possibly this summer when I start on my artillery tractor. In the meantime, if somebody tries these numbers and is successful, please post the results.