Brake & Wheel Specs

This forum is about the Fordson Dexta, Super Dexta and Petrol Dexta.
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bhayden
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Brake & Wheel Specs

Post by bhayden »

One of the first things I noticed after picking up my "new to me" 1961 Dexta was that it didn't stop worth a dang. When the brake pedals were not connected the right side pedal sat a good inch or so lower than the left meaning it; a) had less travel and b) possibly wasn't even fully engaging. This weekend I pulled off the wheels and brake drums. I think the shoes are as thin as I've ever seen without grinding thru to the metal:
Image0812171710 by Alden_Sloe, on Flickr
The good news is everything else seems to be OK. Because of the extent of corrosion I did order new springs and hardware along with the shoes. The manual specs the brake drums as 14" and I measure 14.015" ID for the right side and 14.010" for the left. There's no grooves or ridges so I'm tempted to not even have them machined.

Question #1
What is the max size that the drums can be turned to. It's often cast into automotive drums (back when cars had drum brakes :mrgreen: ). Or, with a tractor do you just turn them until they fail?

Question #2
What is the torque spec for the lug nuts? This may be a newbie stupid question but all the shop manual says is "tighten the nuts securely". Ya think! :scratchhead:
I did find this reference at OldFordTractors.com which says 80 ft-lbs (that's 5.7 foot-stone in old money :P ). I'm guessing an 8N would be about the same as a Dexta.

-Bernie

mathias1
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Re: Brake & Wheel Specs

Post by mathias1 »

bhayden wrote:
Question #1
What is the max size that the drums can be turned to. It's often cast into automotive drums (back when cars had drum brakes :mrgreen: ). Or, with a tractor do you just turn them until they fail?



-Bernie
I know that new drums are up for sale, as also for the shoes. With cars, they just replace the drums when they are getting to thin. I wouldn't leave them on, just until they fail.
http://www.qtponline.com/products/brake ... e=combined
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charlie63
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Re: Brake & Wheel Specs

Post by charlie63 »

Bernie,
In my opinion I wouldnt go to the expense of replacing the brake drums as 10 and 15 thou is nothing over the overall size of the drum and if they are not grooved or ridged then they should be fine after all its not as though you are going to be doing any high speeds with it. When I rebuilt my brakes I went down the route of replacing the linings which was a fraction of the cost of buying a complete set of shoes for it. Not sure if you are confident in doing that but its a straight forward job. As for the wheel nut torque I never bother torquing them but nip them up and then just go round them again with my breaker bar and give them a final nip up.
Regards,
Charlie

bhayden
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Re: Brake & Wheel Specs

Post by bhayden »

Thanks Charlie,
Cars are usually good for .060"-.080" over on drums so I'm sure mine have lots of life left. There's no ridge to mention and given how far inboard you can adjust the brakes shoes I'm not worried about the drums hanging up. I'm trying to decide if it's worth even having them machined? I guess it would tell me if they are out of round at all. I read that the original shoes are pre-drilled to rivet on new linings and mine do indeed have the holes. But I don't know what size and type of rivet to use and I'm guessing I'd have to buy a special tool since the only rivet gun I have is a cheapo pop-rivet job.

I also don't have a clue as to how to remove the old linings. Although, there's not much left of mine so I guess just a grinder :scratchhead:
I figure get it put together with new shoes and springs and I'll likely never have to touch it again. But just for fun I might reline the old shoes as a winter project.

One other thing I was thinking of was replacing the countersunk straight slot screws with an Allen or Torx drive. They came out OK but a straight slot seems like you're just asking for trouble down the road if/when these get rusted on. :eyes: I've never seen a drum with retaining screws like this and not really sure why they are needed.

-Bernie

charlie63
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Re: Brake & Wheel Specs

Post by charlie63 »

Bernie,
Your drums sound as though they are in pretty good condition and if it was me I wouldn't go to the expense of getting them machined.
Replacing the linings is a pretty straight forward and easy job and if you purchase linings you usually get the new rivets along with them.Remove the existing lining rivets with a grinder and then using a punch remove whats left of the rivet. Give the metal shoe a clean up with a wire brush where the new lining is going to sit to remove any loose material. Get a flat headed punch the same size as the head of the rivet or slightly smaller and fix securely in a vice just so the punch is sitting around half an inch proud of the top of the vice. Sit the new lining on to the metal shoe making sure all the rivet holes line up and set in a new rivet in the centre. Turn the shoe upside down and set the head of the rivet on to the punch. Using a small ball pien hammer use the ball end and flatten over the head of the rivet making sure not to damage the rivet or the new lining( the punch gives the head of the rivet a solid base to sit against). You will find it will flatten easily as the are brass. Repeat the process for the rest of the rivets and there you have one shoe completely relined. Do the same for the remaining three shoes. This is the same process as what I use when replacing the linings on the winch brake bands on the cranes and at around 80 -100 rivets per brake band it takes a while to replace them lol.
As for the large drum retaining screw that is the type that was fitted to all brake drums I ever had the pleasure of having to remove. If it becomes seized a bit of heat on the head with a gas torch and using a punch and hammer to start them usually removes them no problem. When refitting put some copper grease on the threads that will stop them seizing up.

Regards
Charlie

kiwimc
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Re: Brake & Wheel Specs

Post by kiwimc »

Hi Bernie,
just remember those linings are likely to be good old-fashioned asbestos.
The world won't stop, but do try to avoid inhaling any dust you make when doing the grinding thing.

Regards,
John (& yup, I've had OSH responsibilities in a past life).

charlie63
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Re: Brake & Wheel Specs

Post by charlie63 »

John,
Good point there which I forgot to mention. Ive had many a dealings with the good old asbestos dust from brakes and clutches years ago. I remember when I was serving my time back in the early 80"s and when we were servicing a car my old boss said remember and give the brakes a good blow out with the air line and oh remember and hold your breath as well whilst doing it. Being young at the time what the boss said went of course and remember the workshop being full of a big dust cloud. Its nasty stuff and my wifes aunt passed away recently form lung cancer/asbestoses which we found out had been from her working in a paper mill/factory for years a long time ago and breathing in the fine dust articles.
So Bernie remember and wear a dust mask if your going to be grinding at those brake shoes.

bhayden
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Re: Brake & Wheel Specs

Post by bhayden »

John, Charlie,
Good reminder on the asbestos. I've been dealing with this artifact of old technology over the last few years. First replacing 1961 vintage asbestos floor tile in our home with hardwood. Then the "pop corn" ceiling in the rental Shark <funny censor bleep for a place where you live :lol: ) we sold. Now ripping out drywall and insulation in our guest house remodel. The good news is there's only a 1/16" [1.6 mm] of lining left on the old shoes.

One reason I went with ordering new shoes rather than relining was an expectation of completing the job sooner. That went sideways when the first shoes they shipped were the wrong part. Received the replacement shoes today, a week later. The original parts they sent were bonded without rivet holes. The replacement shoes are riveted so I can see how that works just as Charlie described:
ImageP1000825 by Alden_Sloe, on Flickr
ImageP1000824 by Alden_Sloe, on Flickr
The construction of the shoes is slightly different so I think they are remanufactured copies rather than relined original parts. But they appear to be decent quality and with a complete new spring and hardware kit cost $180 USD delivered to my door. I'll plan on replacing tomorrow and take some more pictures.

-Bernie

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