Hawk, U/J - chassis interaction!

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simonjrwinter
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Hawk, U/J - chassis interaction!

Post by simonjrwinter »

On my car I've noticed that if I hit a REALLY BIG bump in the road, the RHS of the chassis contacts the U/J (which is spinning at great speed) with one hell of a BANG!
Yesterday I carried a passenger and while travelling, we hit a bump that made both sides BANG....
As you can see from the pictures, the spinning U/J has carved lumps out of both sides of the chassis and this sort of "interaction" can only lead to catastrophic failure in the U/J-driveshaft area. My car runs and drives beautifully apart from that, I don't want harder springs, I don't want harder damper and I certainly don't want to raise my car any more (it already has the look of a 4x4 from the rear and towers over Dax, GD and other makes)
Surely this can't be right???????
chassis 1.jpg
chassis 2.jpg
chassis 4.jpg
chassis 5.jpg
chassis 6.jpg
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peterc
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Re: Hawk, U/J - chassis interaction!

Post by peterc »

That’s weird.
I have my exhaust running under that part of the chassis and I only have a tell take mark on the drive shaft itself.
I’ll have another look tomorrow.
Peter C
Last edited by peterc on Mon Aug 09, 2021 5:34 pm, edited 2 times in total.
SiJackson
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Re: Hawk, U/J - chassis interaction!

Post by SiJackson »

I've had the same problem on the nearside. I've gone up another 15mm and wound the dampers up 5 clicks, but the ride is now harsh. I'm thinking of pulling the dampers apart and fitting progressive bump stops to the damper shafts. If that doesn't work I'm going to scallop the chassis and gain another inch of space.

It was quite a scary moment when the shaft hit. A double dip in the road at about 60. A huge bang and on the second hit the rear of the car went a few feet up into the air and landed sideways. I've had the shaft out and checked it and all is fine.
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simonjrwinter
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Re: Hawk, U/J - chassis interaction!

Post by simonjrwinter »

Seems I’m not alone then. I seem to think I’ve seen a picture somewhere of an adaptation someone has had done to make a recess in the chassis at that precise point. Can’t find it though.
Simon
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kdavies3
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Re: Hawk, U/J - chassis interaction!

Post by kdavies3 »

Hi Simon,
As suggested, if you don't want to alter your settings and I don't blame you.
The only thing would be to add larger bump stops on the damper rods.
Kev Davies
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simonjrwinter
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Re: Hawk, U/J - chassis interaction!

Post by simonjrwinter »

Found a thread about it but no pics....https://www.the289register.com/phpBB3/v ... 439#p10439
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Migge
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Re: Hawk, U/J - chassis interaction!

Post by Migge »

I can't see it on the pics for sure. But are your wheel on the inside very near the frame tube? Like very short Jag running gear?
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simonjrwinter
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Re: Hawk, U/J - chassis interaction!

Post by simonjrwinter »

They are apparently the correctly shortened length.
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clive
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Re: Hawk, U/J - chassis interaction!

Post by clive »

What tyre pressures are you running? Have you thought about stiffening the dampers and reducing the tyre pressure? Also, how far does the car settle when there are two in the car? 289s generally ride higher than Dax, GDs etc. If you ask Gerry he will tell you most owners have their cars too low.
Cheers, Clive.

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Migge
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Re: Hawk, U/J - chassis interaction!

Post by Migge »

Clive, the set up should be made with some space for a few corrections so that every one can make their favorite adjustments. If that problem exists on all cars with Jag axles it is bad. It is not correct to allow just a special ride high and I'm not talking of very very low. It's maybe necessary to cut off a small curve of the square tube to allow more suspension range with Jag axles.
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