289 build

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clive
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Re: 289 build

Post by clive » Thu Jun 18, 2020 12:03 am

Thinking back, Allan Tunstall had problems grounding out in dips in the road, and following him it was obvious that his suspension was too soft. Stiffening the shocks cured the problem.
Cheers, Clive.

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amulheirn
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Re: 289 build

Post by amulheirn » Mon Jun 22, 2020 8:58 pm

I'll give that a try, thanks. It is definitely the rear clamp at the lowest point that is taking the hits.

I have some polybush spring pads arriving tomorrow and hope to remove a spacer or two.

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amulheirn
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Re: 289 build

Post by amulheirn » Tue Jun 23, 2020 10:39 pm

Okay - I am befuddled...

I removed the two packers on the passenger side, put it all back together and then measured the top of the wheel rim to the wheel arch on both sides. On the passenger side the distance is 7 1/8", and on the drivers side, 7 1/2". This was after bouncing the back end up and down quite a bit to make sure it sat properly.

So instead of raising the car, it has lowered it by 3/8". The packers added up to 3/4".

What I *should* have done of course is measure that distance on the passenger side *before* I spent an evening sweating my berries off in a concrete garage that had been heated up by the sun like some kind of infernal storage heater. Needless to say, I'm now on the sofa having a cold beer.

What are your thoughts?

Here's my drawing - the spring is effectively part of the chassis, being fixed at each end. That hasn't changed.

The distance from the centre of the axle to the edge of the tyre hasn't changed of course either. All that has happened is that I've moved the axle closer to the spring

The side I took the packers out of was the side that almost always grounded over depressions and bumps. So I wonder if a possible explanation might be that I have assembled one side incorrectly? That said, there's not much you can do wrong - the front end of the spring has to go in the upper hole because the lower one is for the anti-tramp bars isn't it?

More investigation required...
drawing.jpg

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amulheirn
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Re: 289 build

Post by amulheirn » Sat Jun 27, 2020 11:51 pm

Well I checked with Gerry and he said the packers were optional - included to lower suspension if required. Removing them would raise the car. I really, really, REALLY should have measured before making the change. Fffff...fiddlesticks.

Anyway - my better half has invited a government-approved number of female friends to our patio tonight. They are drinking mojitos, so I took a mojito down to the garage to do the other side.

I decided that measuring wheel-arch to floor through the centre of the spinner was better - but as I type this that is obviously nonsense because differing tyre pressures from one side to the other might affect things. Rim to arch was probably better. But of course on this second visit to the problem I didn't do the rim to arch measurements - only floor to arch. :(

Ultimately, the proper thing to do is compare the same side with the same side - not left against right. I think the only way to solve this is put the packers back in (or sod it and see how it drives!).

Anyway, after tonight's work, measuring arch to floor I got this:

Starting point:
  • Near side (packers removed) - 27 1/2"
  • Off side (packers still in) - 27 3/4"
After removing off side packers:
  • Near side (packers removed) - 27 3/4"
  • Off side (packers removed) - 28 3/8"
So on the off side, the car has definitely risen by almost the height of the packers. And the nearside (unchanged this evening) has gained a quarter inch. Gerry is (or course) right - removing the packers raises the car.

All this means the care probably rides 3/4" higher than it did before so that may make enough difference to stop the sparks at the rear.

Maybe the weather will improve to give it a try tomorrow...

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Dave Woodward
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Re: 289 build

Post by Dave Woodward » Sun Jun 28, 2020 9:33 am

Very precise work Andy.

All I know is I can get two fingers under the arch on both sides 👉.
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StewbieC
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Re: 289 build

Post by StewbieC » Sun Jun 28, 2020 12:50 pm

Hi Dave,
You've also got lovely Avon tyres that are a bigger diameter to Blockleys, Verdestein classics and Pirellis so your ride height will be slightly higher and gap to the top of the wheel arch may be smaller by default.
Great work Andy,
It won't completely solve the problem but it will certainly be better. One way is to increase the length of the bump stops and perhaps fit MGB ones which will give a cushioned stop rather than allowing for the exhaust clamp to spark out. I had to replace one of my clamps as it wore through.
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Hawk 289, maximum smiles per mile..

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peterc
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Re: 289 build

Post by peterc » Mon Jun 29, 2020 9:02 am

Don’t assume that the two wheel arches are exactly the same height and curvature both sides. Perhaps other 289 slab side members can advise if theirs are similar dimensions. I have checked my FIA and they are reasonably the same but I know that the headlights for example are a fair bit different in height. Moulds would have been taken off an original (potentially repaired) car and of course they were all hand made anyway.
Get the chassis level and then conduct a corner weight check with suitable ballast on the drivers seat.
Peter C

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