289 build

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Roger King
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Re: 289 build

Post by Roger King »

peterc wrote:Can't believe I read that.
Roger admitting to fitting a bracket that wasn't on the original car.
Good idea though and probably stronger than my setup.
Peter C
Well, that was on a fibreglass car that was miles off anyway!

Original cast ally bracket from an original Cobra, sourced in the US, on my curret car
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amulheirn
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Re: 289 build

Post by amulheirn »

I'll need to have a think about that then... I've just relied on the GRP at the lower end, which was thicker than I expected it to be, but perhaps a bracket might be worthwhile.

Progress today - finshed off the brake pipes to the master cylinders:

Image

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amulheirn
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Re: 289 build

Post by amulheirn »

The balance bar setup is a bit odd. Basically it is a Tilton balance bar, but the sleeve that you'd expect in the pack isn't there. Instead, it is already welded into the brake pedal by Hawk's fabricator.

An addition to the kit is a pair of aluminium 'movement restrictors' that Gerry supplies. These aren't covered by the Tilton guide or the Hawk build manual. They are included so that if a circuit fails, the balance bar is restricted to 10 degrees of movement, enabling the other circuit to carry on doing some braking.

Here's what you get in the kit, plus some drawings to illustrate how it works:

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Here's a dismantled shot - the 'thingy' in the diagram is the Hawk-supplied movement restrictor:

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These movement restrictors are wound right up to the tapers either side of the central spherical bearing and loctited in place.

Since the sleeve and brake pedal isn't exactly centred between the two brake master cylinders, I had to do a bit of thinking on the assembly. Here's what I did:

1. Put the movement restrictors on, and loctite in place. (They are yet to be wound up to the taper in this photo):
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2. Put bar into sleeve in pedal to make sure it fits - I had to remove some powdercoat.
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3. Measure centres of two cylinders:
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4. Halve that figure and wind one barrel nut/clevis onto the balance bar.
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5. Put the balance bar into the sleeve. Wind the first master cylinder into the clevis. It must go in at least 6 threads. I did this by rotating the entire master cylinder, since the clevis could not be rotated (obviously).
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6. Put the other barrel nut/clevis on the other end. Make sure the centres of the two barrel nuts are the same spacing as the centres of the master cylinders:
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7. Attach the second master cylinder to its clevis:
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The Tilton instructions talk about adjustment from this point on, but that can only be done once the brake system has fluid in it - I wasn't at that stage, so I'll do that later.

Andy
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peterc
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Re: 289 build

Post by peterc »

Andrew, perhaps someone with a MGB axle can advise on the initial setting for the bias on the balance bar.
I set mine visually 50/50 and haven't needed to adjust since but then my axle is Jag so the rear of the car is heavier.
Peter C
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StewbieC
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Re: 289 build

Post by StewbieC »

I set mine about 50/50 (princess. 4 pot and drums back) and got it set up at an MOT testing station. Got mine MOT'd prior to
IVA as long as it was insured and driving to and from a pre booked test you could legally drive on the road without plates. I even drove mine to the IVA test in B'ham. I think you now have to trailer to and from.
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Stu
Hawk 289, 66 Mustang Fastback with a 289 maximum smiles per mile..
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clive
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Re: 289 build

Post by clive »

As advised by GH, mine was adjusted max to the front (Ford 302 Princess 4 pot calipers front and Jag diff with inboard discs rear) as the rear brakes are more efficient than the front. Attached is the SVA brake test data showing the results.

Image

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Cheers, Clive.

(If I'm not here I'm in my workshop or on the golf course!)
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peterc
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Re: 289 build

Post by peterc »

I didn't get any print outs for my SVA but then they did make the comment that the brakes were so new they needed to be bedded in. You could see the criss cross grinding marks still on the front discs. So he got me to perform two emergency stops across the empty lorry parking area and then proclaimed that everything was perfectly OK.
I had obtained an MOT prior to driving to the SVA so I knew it should all be OK.
Peter C
IainS
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Re: 289 build

Post by IainS »

I think I'm right in saying an MOT brake test measures general efficiency and is more concerned with left/right balance to ensure the car doesn't pull under braking. It assumes a production car has the correct front/rear balance.

The IVA test involves a pressure pad on the examiners foot so there is a measure of relative driver input force and output, both measured in Kg. It's a pain because there is no real way of measuring this pre test and yet it's an easy tweak of the balance bar....accept of course that needs to be locked and non-adjustable for the test....

Iain
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StewbieC
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Re: 289 build

Post by StewbieC »

Mine was set up to ensure the back had best braking force without locking up. As the 4 pots have a much better grip than the drums at the back it was a smidge off 50/50 in the end. Mine sailed through IV?a on the brake test and only failed on washer bottle size and rear fog light.
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Hawk 289, 66 Mustang Fastback with a 289 maximum smiles per mile..
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amulheirn
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Re: 289 build

Post by amulheirn »

Thanks all - I will bear this advice in mind. I've yet to fill the system, so it can't be adjusted yet.

Progress last night - fitting the accelerator pedal. I made a counter-bracket to go inside the foot box - welded some nuts on it to make life easier. The welding isn't all that pretty but it does the job:

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Then, after a fair bit of measurement and trial pilot holes, we drilled a big one and installed it. Quite rigid with the bracket attached, so I think that was a good decision. The photo's at an angle and the pedal isn't sprung yet, so it looks very close to the brake pedal - it is actually 11cm from the brake - same as the clutch.:
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Not too sure what to do with the small hole a few inches down the pedal. That must be for a return spring, but none was supplied. I will have to ask Gerry. It's probably a fail-safe in case the carb spring goes.

I think as a throttle stop, I will be fabricating one rather than buying one of these!: http://actoncobra.com/index.php?main_pa ... cts_id=401
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