Ford CMP 8cwt Rear Springs

[david moore]

Advice please!
The rear springs on my F8 definitely need new bushings - I can get spare bushings from Mac's Auto, no problem. But how do I get the shackles apart?
I got the locking pins out OK but the main shackle bolts seems to be screwed in place and have a large slot at the outer end for , presumably, removal by a monster screwdriver - but they are solid even with plenty of heat supplied. There is nothing mentioned in the F8 manual to tell what the design of the bolt is like i.e where it is threaded into the hanger- and the later 1943 manuals (that don't mention the 8cwt) have a completely different type of shackle bolt shown with convenient nuts exposed at each end just like my front ones are..

If mine are supposed to be driven out, no way since I can't get to the back of them.

Advice or help greatly appreciated!

David

[Bob Carriere]

Bonjour Dave

A picture might be worth a few thousand words.....

On the cab 11 frame they have a special opening to insert a brass drift pin that can then be hammered nto drive the shackle pins out ........

Bob C.

[david moore]

Bob
Yes, I'll take a photo when I'm back at the cottage next week. On the cab 12 there is no hole back of the shackle bolt, either in the hanger casting or in the frame behind it so double jeopardy!!

They are simply driven in then, not screwed?

What is the purpose of the slot on the face of the pin I wonder? Just to be able to rotate the bolt ( when its newly installed and moveable!) so that the lock pin will engage properly?

I just can't think how I'm going to get it out - it's going to be real hard steel I imagine and too big to drill out anyway. Looks like I may have to drill an access hole through the frame and then through the shackle casting so I can punch it out. Ughh..

[Bob Carriere]

Don't start cutting holes until we can figure out if it is not screwed in place...... let's see a picture first.

I am surprised that no one else with C8 expereince has not yet chipped in.......

Some old ...late 30 Chevs had the pins made with thread at both ends with nuts holding them in place.

I had to have new pins made by a local machine shop as the old style could not be sourced anywhere.

Will check Rob Clarke's HUP...... it has a whole bunch of odd parts that are not compatible with regular cab 13 CMP......

Hang in there.

Bob C

[Tony Smith]

Originally posted by david moore
What is the purpose of the slot on the face of the pin I wonder? Just to be able to rotate the bolt ( when its newly installed and moveable!) so that the lock pin will engage properly?

Correct. The pin is pushed in hand tight (in 1941 they had strong hands), and the slot is to rotate the pin to align the locking cotter pin. Perhaps an Air-powered rattle gun with a screwdriver bit to free it up while you apply heat? If you had the larger pins from a bigger CMP, you could thread a slide hammer into the grease nipple thread in the end. It would seem odd there is no access hole to drive out the pin with a punch.

[gordon]

When the bushes wear out they start to wear ledges on the pins, which stops them sliding right out becuase the weight of the spring is effectively locking the pin in place, so be sure to try and get it out with all the weight off the spring...

Dodges have a very similar system of 'headless bolts' and they can be a pain.

I think I'd be a little creative and bore a 3/8" hole through the back of the chassis and hanger so I could get lots of lube in there and drift the pins out - you could always weld them up afterwards as I don't expect you'd be worried about the problem happening again during your days of ownership ?

Gordon

[Lynn Eades]

Like Gordon says, the Dodge has a similar set up. The dodge has a hole through the chassis behind the hanger, but it doesn't line up with the pin! Unfortunately the pin can rust and grow at the end because the grease seldom gets this far in. So there are not many options. I would lube the pin as best I could and try punching it in further. can you now turn it? now try the slide hammer. work it back and forward ,turning it a bit at a time.( with plenty of penetrating oil). A bit of patience is required. If you can't make any progress this way you'll have to go down the track Gordon suggested. A hole inside the chassis behind each spring hanger is a far better option than removing and re riveting spring hangers. Dont make the hole too small. Dont use too small a punch. A few decent hits with a good sized hammer, should get it moving.

[Phil Waterman]

Originally posted by gordon
When the bushes wear out they start to wear ledges on the pins, which stops them sliding right out becuase the weight of the spring is effectively locking the pin in place, so be sure to try and get it out with all the weight off the spring...

...

Gordon

Gordon - very good point about the ledges worn in the shaft, supporting the end of the springs so that they are nether hanging on the pin or pushing up would seem to be a good starting place for any spring pin removal effort. The ledges when well engaged can make driving the pins very difficult, using an air chisel with a half inch drive pin I mushroomed the end of the drive pin.

If the ends of the pins are truly threaded into the shake then the trick is really going to be how to turn the pins without destroying the slots.

Attached is a drawing of how I improvised a puller after re-taping the grease-fitting hole to take a bolt. By this point, figured the pin was a right off, it worked and I had an extra pin.

[gordon]

... if you have the bolt with a grease fitting hole in it - what us Dodge people call 'headless bolts'

Because of the ledges mentioned before, and when sometimes the whole centre section of the bolt is displaced (wear on one bit allows the opposing face to be pushed down - looks really odd to see.) the trick with all these bolts is to turn them when pulling.

The Dodge grease fitting threads start off as NPT (National Pipe Taper) which is basically the same size as UNF but with a taper on it. This means you can screw a UNF bolt in to pull it, but normally it grips on so few threads the threading gives up before the bolt moves.

So - the trick? Go and buy the biggest reverse screw tap extractor you can find that will fit in the hole. I have one somewhere that has a 3/8" square drive on one end, and the tapered section varies from about 3/16" to about 1/2".

I just hammer this in the grease fitting hole and start turning anti-clockwise on the square drive. I've never yet had a headless bolt that wouldn't turn using this tool, and I've never yet had one turn that wouldn't draw out neatly once it had turned a few times.

No use at all if you just have a slot and no grease fitting hole, but if you've got a grease fitting hole the reverse thread tap extractor is the way to go.

Gordon

[david moore]

Thanks everyone for you comments - here is a picture of the problem bolt - the lower one in the picture. As you can see the grease fitting comes in at the side and not in the actual bolt.

The consensus seems to be that it is simply driven in, not screwed in. I did find a small hole (~3/8) through the frame lined up with the bolt - it had been filled with muck -- and so I thought "great now it will be easy with a drift to drive it out"! I had taken up the weight off the spring so the spring moves along the bushing a few mm each way by a finger touch.
Not so fast! Even with heat, soaking in Liquid Wrench for several days and using a 5 pound hammer on the drift, it has not budged a fraction. I tried turning it by carefully driving on the outer slot but no luck either.

Anyway - here's the picture of the *!##@* thing!

David

[Max Hedges]

David I have found over the years that at times like this you need to use the biggest hammer you can swing to drive the bugger out.Once the bolt moves out a fraction knock it back in and then try driving it out, if jams knock it in again and repeat the process.
Max

[david moore]

The advice to hit that bolt as hard as possible with something as heavy as possible worked! What a joy! Here it is! Worn down quite a bit - there was no bushing at all!

Thanks to all for encouragement!
David

[gordon]

One good whack with a alrge hammer and you're done.

You could hit them with a small hammer all day and it would just laugh at you.

That's not the most worn one I've seen - by a long way. I have a MUCH better example if I could just find it.

G

[Dirk Leegwater (RIP)]

Originally posted by david moore
Here it is! Worn down quite a bit - there was no bushing at all!

Hallo David,

What is the measure of the pin ? Dia 3/4 and length 3 1/2 inch ?

Mvg. Dirk