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Kristian

Front Vibration

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Kristian
5 minutes ago, pistonbroke said:

Even new bearings have been found to be faulty , so worth you checking them out , otherwise Ian might have the answer above ?

 

 

I'll check them too. I have to do as Ian says, take the upright to a lathe.

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Kristian
16 minutes ago, Ian Kinder (Bagpuss) - Joint Peak District AO said:

 

Others have had manufacturing issues with the Hispec items. Some have found that when the bearings where pressed into the hub, they scrape a small piece of aluminium off, which then sits under the bearing housing. This then makes it out of true and causes issues.

 

There's a diagram here of the upright and stub shaft.

 

http://www.hispecmotorsport.co.uk/cortina-uprights.html

 

I'd be taking the stub shaft out and looking for issues in the areas arrowed:

 

image.png.9c137e6dfb4263d2eae46a5b6e7455ea.png

 

You could put the stub shaft in a lathe to check for run out.

 

This seems like being the next step. Your thoughts about tolerance limit for run out on the hub? 

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Mighty Mart

Hi mate,

 

Sorry to hear about your issues. In my opinion, the run-out on the hub is 100% the cause of the problem and no need to look elsewhere....

 

As above, the stub shaft is the likely cause, but you could try a quick experiment to counteract the run out.....quicker than taking the stub axle apart. Once the 'experiment' works, you can then be confident that the stub shaft fix is the way to go?

 

As long as you know the rims are true......

 

get hold of some engineering shim - looks like you need 0,13mm thick and cut a small section say 25mm x 25mm ish and place on the hub at the low point on you DTI - stick it on with a bit of grease.....

 

Carefully mount the rim without dislodging the shim and bolt up. Check the rim runout with the DTI and re-shim as required until rim is as true as you can get it.

 

(Cutting the shim down and mounting it nearer or further from the centre of the hub will 'jack' out the low spot of the rim btw)

 

Ill wager driving (carefully) up the road after doing this will prove its the hub throwing out the rim  - obviously exaggerated on the larger dia rim.... 

 

Don't drive around like that though.....fix the stub axle / shaft first!

 

HTH,

 

Mart.

 

 

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Kristian
5 minutes ago, Mighty Mart said:

Hi mate,

 

Sorry to hear about your issues. In my opinion, the run-out on the hub is 100% the cause of the problem and no need to look elsewhere....

 

As above, the stub shaft is the likely cause, but you could try a quick experiment to counteract the run out.....quicker than taking the stub axle apart. Once the 'experiment' works, you can then be confident that the stub shaft fix is the way to go?

 

As long as you know the rims are true......

 

get hold of some engineering shim - looks like you need 0,13mm thick and cut a small section say 25mm x 25mm ish and place on the hub at the low point on you DTI - stick it on with a bit of grease.....

 

Carefully mount the rim without dislodging the shim and bolt up. Check the rim runout with the DTI and re-shim as required until rim is as true as you can get it.

 

(Cutting the shim down and mounting it nearer or further from the centre of the hub will 'jack' out the low spot of the rim btw)

 

Ill wager driving (carefully) up the road after doing this will prove its the hub throwing out the rim  - obviously exaggerated on the larger dia rim.... 

 

Don't drive around like that though.....fix the stub axle / shaft first!

 

HTH,

 

Mart.

 

 

Hi Mart, thanks!
How would the brake disc impact this test? I believe the discs also makes the car vibrate due to consequential error on the stub and therefor transferred to the disc? Can I drive the car without the calipers and discs up/down my street? Just for checking?

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Mighty Mart
Posted (edited)

Ah.... I see the issue with my temporary fix.....

By doing what I suggest, the rim SHOULD run true, but the disc will still run out....

I would only expect the disc to cause major issues under braking, but if it is running too far out it could be knocking on the pads - hopefully not though!

I wouldn't be running anywhere without brakes just in case!

Edited by Mighty Mart

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Ian Kinder (Bagpuss) - Joint Peak District AO
Just now, Mighty Mart said:

Ah.... I see the issue with my temporary fix.....

By doing what I suggest, the rim SHOULD run true, but the disc will still run out....

I would only expect the disc to cause major issues under braking, but if it is running too far out it could be knockin

The wheel and tyre are are larger weight and at a greater circumference than the disc, so will have a more pronounced effect on the test, than the disc.

 

I'd leave the disc and calliper on for this test from @Mighty Mart

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Kristian
5 minutes ago, Mighty Mart said:

Ah.... I see the issue with my temporary fix.....

By doing what I suggest, the rim SHOULD run true, but the disc will still run out....

I would only expect the disc to cause major issues under braking, but if it is running too far out it could be knocking on the pads - hopefully not though!

I wouldn't be running anywhere without brakes just in case!

Today, the disc brakes on the pads when trying to roll the tire. Proving that something is terrible wrong.

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Kristian

Ian, I think so too.

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Mighty Mart

If above works and is vibration free, except under braking - which should then be awful by the way, once the stub axle is sorted, the braking will come good too if the disc is true, which from your dti measurements, look about right.

I wouldn't run too long like this either as will be putting incorrect forces on the wheel bearings...

Mart.

 

 

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Kristian

I actually managed to get a mechanical garage with lathe check the stub and the seat for the stub... Nice - now we are getting somewhere. 

Agreed that I come tomorrow morning.

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Mighty Mart

Because of the increased run out as you get further out on the dias of the hub, disc and rim, the stub axle shaft needs to be spot on when in the hub - there needs to be no discernible run out at all, so be very interested in what findings you come up with tomorrow.

Keep us posted....

it could be that the stub axle shaft is bent or somehow got ground on the pi**?

 

Or,

 

Taking a look at the exploded assy Ian posted above, IF the shaft is true, the other two areas to check are where the shaft locates on items 10 & 5 - both these faces need to be square with the bore to ensure the shaft sits true, otherwise as everything is pulled up tight, it will throw the shaft off square. I could well be wrong, but I think its the face on the opposite side to the red arrow above on item 5?

 

Mart.

 

 

 

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AdamR

I would say it's the hub at fault. I know it's new and the quality appears good, but that doesn't mean it was put back in the chuck squarely during machining - and your dial indicator test confirms that.

 

A 'wrong' upright or bent stub axle wouldn't cause run out at the hub. The axle itself doesn't rotate, you could fix the hub to a banana and as long as the hub is made correctly it would have no deviation while rotating. Similarly, sticking a crappy hub on the straightest stub axle in the world would make the wheel wobble.

 

As you have stated, any wobble you get at the hub transfers to the disc and wheel.

 

How much deviation is there in the other front hub? And both the rear hubs?

 

As an aside, I am also very particular with my car and all 4 of my wheels have more than the 0.7mm run-out you have. It doesn't bother me, so your issue might be elsewhere. Very hard to track these things down without being in the car but as you can see there is a wealth of knowledge and help here, hopefully with your tenacity we can help to get it sorted!

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Ian Kinder (Bagpuss) - Joint Peak District AO
23 minutes ago, AdamR said:

I would say it's the hub at fault. I know it's new and the quality appears good, but that doesn't mean it was put back in the chuck squarely during machining - and your dial indicator test confirms that.

But what's the odds of both his original Hispec item and his new Siltech both being wrong in this aspect?

 

 

23 minutes ago, AdamR said:

 

A 'wrong' upright or bent stub axle wouldn't cause run out at the hub. The axle itself doesn't rotate, you could fix the hub to a banana and as long as the hub is made correctly it would have no deviation while rotating. Similarly, sticking a crappy hub on the straightest stub axle in the world would make the wheel wobble.

 

Drat, you're indeed correct the hub would spin with no run-out!

 

23 minutes ago, AdamR said:

 

As you have stated, any wobble you get at the hub transfers to the disc and wheel.

 

How much deviation is there in the other front hub? And both the rear hubs?

 

 

23 minutes ago, AdamR said:

 

As an aside, I am also very particular with my car and all 4 of my wheels have more than the 0.7mm run-out you have. It doesn't bother me, so your issue might be elsewhere. Very hard to track these things down without being in the car but as you can see there is a wealth of knowledge and help here, hopefully with your tenacity we can help to get it sorted!

 

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AdamR
5 minutes ago, Ian Kinder (Bagpuss) - Joint Peak District AO said:

But what's the odds of both his original Hispec item and his new Siltech both being wrong in this aspect?

 

 

Given the HiSpec hubs I've seen and measured (4, all of them had that issue), and the video the OP posted (which shows the issue), I'd say close to 100%!

 

I ended up machining my HiSpec ones down a smidge on the disc and wheel mating faces to square them off, having centred the hub on the bearing races in my lathe.

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MR.C

Hi, Kristian,

 I know this is not the problem your having.But I have a very similar spec car to yours.

And ive noticed the  Zetec engine has a vibration zone around 2,250rpm till maybe 2,400rpm.🙃

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