fbekholden.com

Ripping it Drew


FB ute fixer upper, EK van on rotisserie

Cheers Clay but it’s hard work but a big hangover lol.

Hey can anyone tell me an optimal setting for the caster on a drum brake king pin front end?

I know it’s been talked about before but I can locate the info easily.

Should I set the top of the steering knuckle to the front or the rear of the car for maximum caster?

Drew,

Too much caster is not enough for a king-pin front suspension. Specs are 0 - 1 degree positive for wagons and commercials, 1 - 2 degrees positive for sedans (at kerb weight). The difference will be because the rear sits higher in wagons and commercials. I'd go towards the maximum setting, which is with the eccentric nut wound towards the rear. I use one of those stubby little Trojan adjustable spanners to set the eccentric. They're just the right size.

Your front suspension's in the ideal state to measure caster at the moment. Put a couple of 3/8" diameter guide pins through the top holes in the steering knuckle and lay a level on top. But you have to do the measurement with the motor and gearbox in the car, with the car's weight supported by blocks on the outer ends of the lower control arms, and with the stub axles at the normal ride height.

Set the camber zero to half a degree positive (I assume you'll be using radial tyres). When you adjust the eccentric, (do this with the car's weight taken on the lower control arms so the suspension's off the rebound stops) you'll see the outer end of the upper control arm rise and fall as you turn the eccentric. Make the final setting so the camber's correct and the outer end of the upper control arm is at or near the top of its movement.

In short: there's a "sweet spot" every turn of the eccentric nut where the fat part of the eccentric's pointing down, and the camber's correct. Every extra turn of the eccentric nut towards the rear adds half a degree of caster. Get the "sweet spot" and at least a degree of caster on both sides, and you're set.

You can tweak the settings after test-driving the car. If the car pulls to one side, the caster will need further adjustment, but that's for later.

Rob

Thanks Rob for the very informative reply, your info made total sense and I feel I have got the adjustment ASBESTOS it can be for now.
The motor and gear box won’t be fitted for a while yet so I won’t get it spot on until test driving it I think.

I made a funky spanner for the eccentric nut and off set it heavily towards the rear of the car.

And I also put a six pack in the freezer so I’ll be having some beers within the hour!

So finally the front end is built, it’s great to fit everything together without any dramas.

All of the hours of cleaning, blasting and painting have payed off to make it look pretty sweet.

King pins turned out sweet, big thanks to Brett - I’ll be posting your tool back to you in the next day or tool.

I think the standard height king springs will be too tall but at this point I’m just going to get in and drive it.
If it needs lowering I’ll slot it in as a future Drew problem!

New brakes with stainless sleeved cylinders.
Hubs fitted with new bearings and studs.

When fitting the front brake drums I was suspicious of the large gap between the drum and the backing plate.

A bit of investigation found the drum to not be sitting home on the hub due to the form of the new studs.

Looks like I’ll have to open the holes on the drums up.

Lucky I spotted that issue now and now later

Dang - I just ordered a new pair of stock height King springs for the rattler last Friday - I have 2 sets of new lowered springs and a set of second hand lowered springs, we could have done a swap .....

good pickup on the drums, easy fix now not so easy on the side of the road ....

That gap is so that you can get in there with a screwdriver and prize the drum off instead of backing off the slave

Cheers,
Harv

Blacky wrote: Mon Feb 21, 2022 2:14 pm I have 2 sets of new lowered springs and a set of second hand lowered springs, we could have done a swap .....

At least I know who to call when I need the lowered springs!

There is some method in the madness, when I got the rear springs re set the guys said that they will sit pretty high.
So I went for std height just in case it turns out perfect.

If I went lower in the front I’d have to use lowering blocks in the rear which I don’t want to do before rego in case there is some kind of issue and it finds it self over the pits

Harv wrote: Mon Feb 21, 2022 2:58 pm That gap is so that you can get in there with a screwdriver and prize the drum off instead of backing off the slave

Cheers,
Harv

Damn it I knew the gap would be useful for something!

Steering linkage in and diff center in place!!!

With Fraze in mind and his vibration issues I woke up last night thinking of these drum brakes and I thought I’d actually have a look at the drums with open eyes.

I got them machined, traditionally we remove the drums and send them off to the brake joint and they mount them in the machines

Disks however are left on the hub with the bearing races in place so the machine job is concentric to the bearing races.
On drums we don’t seem to do that, well you cant on the back because it’s an axle but on the front you can do it.

So I mounted the front drums in the hubs and measured the run out.
Found them to be running out of true by .006”- .008” which isn’t a big deal I guess but if they were mounted to the hubs when machined and correct rotation was kept or mark a stud and the drum so it goes back the same way every time, it should be perfect.

But it’s old equipment so it’s good enough.

What was a concern was the run out on the outer cast faces.
This would certainly be playing havoc with vibrations at speed.
Nothing I can do about it right now but I think this is why the EKs had modified drums which were flat on the external diameters, not ribbed like the FB.

If I have problems with vibrations I’ll go to EK drums next time and have them mounted on the hubs for machining.

This is the run out in a short video shot below, imagine this at 60mph.

https://youtu.be/UY8jj9Fqfes

Drew,

I'm impressed that you measure everything. Factory run-out spec is 0.002".
And I'm not certain that EK drums have the un-ribbed mounting flanges. I think the EJs were the first with flat flanges.

Rob

P.S. - I just watched the "run-out" video. That's nothing. You ought to see the LHF drum of my Humpy. The casting runs so far out of true that the drum turns itself by its own imbalance. I have to balance the tyre, wheel and drum as an assembly, and mark the wheel and drum for position.

Thanks Rob for the compliment.
EJ drums would still work with FB brakes?