27 replies to this topic

[Curley]

 

 

And the cost? £12.65 front and £13.85 rear.

About 185£ in today's money according to the inflation calculator. Amazing

 

Not to far over what a decent set costs today. I use the KAD ones because they have the hex drive.

[hazpalmer14]

And the cost? £12.65 front and £13.85 rear.

About 185£ in today's money according to the inflation calculator. Amazing

Not to far over what a decent set costs today. I use the KAD ones because they have the hex drive.

So do the minispares genuine hilos. They also sell the long Allen key to adjust them as well.

[Tornado99]

Why are HiLo's popular for road cars? If ride height needs fiddling due to rubber cone wear, one corner not where others are, by tweaking with HiLo's isn't it just putting a bandaid on the bigger problem (worn rubber)?

[nicklouse]

Why are HiLo's popular for road cars? If ride height needs fiddling due to rubber cone wear, one corner not where others are, by tweaking with HiLo's isn't it just putting a bandaid on the bigger problem (worn rubber)?

if you are using it to fix a service issue then you are using them incorrectly.

 

HiLos increase and change the way the rubber spring operates. and they are used to lower the car to change the suspension caricature. or raise it to give better clearance where needed.

 

if the rubbers are FUBAR they will just make things worse.

[JeremyduP]

Prior to this the common practice was shimming or cutting the taper cones to get the ride height required. IMSMR it was 3:1 or 5:1 front or rear or something similar. I’m sure someone with more knowledge will be along to confirm or deny.

 
Perhaps a little bit more 'history' here?
 
The Ratio for the Rear (5:1) is correct, however, the Ratio of 3:1 was first Published it seems by Clive Trickey, who wrote a series of books on modifying an 850 Mini for racing. Clive it appears was one of the first to publish any books on the subject, next to perhaps Special Tuning.
 
However, while this ratio has been perpetuated over the years, appearing also in David Vizards book How to Modify your Mini, sadly, it's incorrect.
 
The Ratio for Dry Front Arms, as I've measured it is 4.45:1 - a long way from 3:1 !
 
 
When the new later day 'Hilos' are fitted up, most it seems use an M20 x 2.5 mm Bolt for the adjuster.
 
One full turn on the Front with these changes the height by (near enough) 11 mm.
 
One full turn on the Rear with these changes the height by 12.5 mm.

I have recently adjusted my front suspension assuming a 3:1 ratio and I have to say the ride heights came within a millimetre of my calculated figure so I am convinced 3:1 is correct.

[Spider]

 

 

Prior to this the common practice was shimming or cutting the taper cones to get the ride height required. IMSMR it was 3:1 or 5:1 front or rear or something similar. I’m sure someone with more knowledge will be along to confirm or deny.

 
Perhaps a little bit more 'history' here?
 
The Ratio for the Rear (5:1) is correct, however, the Ratio of 3:1 was first Published it seems by Clive Trickey, who wrote a series of books on modifying an 850 Mini for racing. Clive it appears was one of the first to publish any books on the subject, next to perhaps Special Tuning.
 
However, while this ratio has been perpetuated over the years, appearing also in David Vizards book How to Modify your Mini, sadly, it's incorrect.
 
The Ratio for Dry Front Arms, as I've measured it is 4.45:1 - a long way from 3:1 !
 
 
When the new later day 'Hilos' are fitted up, most it seems use an M20 x 2.5 mm Bolt for the adjuster.
 
One full turn on the Front with these changes the height by (near enough) 11 mm.
 
One full turn on the Rear with these changes the height by 12.5 mm.

I have recently adjusted my front suspension assuming a 3:1 ratio and I have to say the ride heights came within a millimetre of my calculated figure so I am convinced 3:1 is correct.

 

 

Ah, OK,,,,, sure.

Can you just check me here then ?

 

This isn't how I measured it to come up with the figures I've quoted but is close enough I think here. Top Arm from a Dry Subframe, with the ruler close to the Pivot Shaft Center Line;-

 

 

 

I make that to be approx 170 mm

 

 

And from the Shaft Center to the Cup that's about 32 - 33 mm is it ?

 

 

So, can you be kind enough to work this out for me?

 

170 ÷ 33 = ???

 

 

 

[GraemeC]

Is that not just leverage ratio though Spider? Do we not need a bit of trigonometry to find the difference in vertical height for a given angular rotation of the arm?

 

Using your two dimensions and doing a very basic sketch - for an arbitrary 15 degree rotation I make it that a point at 33mm (knuckle seat) will move up by approx 8.5mm whilst the point at 170mm (ball joint) will move up by 44 so a fraction over 5:1!!

Edited by GraemeC, 29 July 2020 - 09:15 AM.

[Gilles1000]

That's the same theorem behind this. Thales.

It says if you do the 170/33 ratio you will get the same ratio on the height, i.e (movement on the pivot) / (movement on the knuckle joint)

 

Your method is good too, I had to check Spider's one as well to be sure ;)

 

Cheers

[nicklouse]

but the pivot point is not at 170 as the ball is not there and the ball joint stud is at 90 degrees to the arm and the arm is not horizontal.

[Spider]

Is that not just leverage ratio though Spider? Do we not need a bit of trigonometry to find the difference in vertical height for a given angular rotation of the arm?

 

Using your two dimensions and doing a very basic sketch - for an arbitrary 15 degree rotation I make it that a point at 33mm (knuckle seat) will move up by approx 8.5mm whilst the point at 170mm (ball joint) will move up by 44 so a fraction over 5:1!!

 

 

That's the same theorem behind this. Thales.

It says if you do the 170/33 ratio you will get the same ratio on the height, i.e (movement on the pivot) / (movement on the knuckle joint)

 

Your method is good too, I had to check Spider's one as well to be sure ;)

 

Cheers

 

 

but the pivot point is not at 170 as the ball is not there and the ball joint stud is at 90 degrees to the arm and the arm is not horizontal.

 

Cheers guys and it's nice to see you are on the ball, although, just getting rough numbers, the above photos I feel well illustrate that it's closer to 5:1 than 3:1. I did also say in my posting;-

 

This isn't how I measured it to come up with the figures I've quoted but .......

 

 

I did at one point start to calculate it, but it was so much simpler, faster and spot on accurate to simply measure it. I don't have a full set of photos, as I only snapped a couple off when doing this for my own later reference, but what I did was to set up a subframe on the bench, with arms and a hub in one side, lift the hub in increments of 0.100" from full droop to full 'compression' and measure the 'lift' on the arm itself. This is one of my own 'reference' photos from when I made these measurements;-

 

 

The ratio does vary a little over the total travel, but averaged out (for Dry Arms) at 4.45:1.

 

 

I do have an article written by a BMC Engineer from 1961 in which he stated that the Front Arm Ratio was 5:1 however, these Arms were superseded in 1961 or 1962 to types that have the ratio we all have now.

[JeremyduP]

I do have an article written by a BMC Engineer from 1961 in which he stated that the Front Arm Ratio was 5:1 however, these Arms were superseded in 1961 or 1962 to types that have the ratio we all have now.

 

I'm confused now.  What ratio do we all have now?  3:1 ?  Certainly the calculation seems to be 5:1 based on your figures.

Edited by JeremyduP, 30 July 2020 - 10:55 AM.

[JeremyduP]

Interesting quote from the Mini Mania forum suggests the ratio is not the leverage ratio, but doesn't explain how it is determined.

 

"The ratio for lowering the front has been distilled down to a widely acknowledged 3 to 1; i.e. to lower the car an inch and a half, half an inch needs removing from the knuckle joint end of the trumpet (3 x 1/2" = 1-1/2"). However, this ratio is not linear. The more you want to lower the car, the ratio decays slightly, so err on the lesser side of the required amount. If too much is taken off, you will have to strip the whole thing down again and put shim-washers in to get the height back up to where it is required. And incidentally - the 3 to 1 ratio is NOT the actual suspension leverage ratio."

 

 

[Spider]

 

I do have an article written by a BMC Engineer from 1961 in which he stated that the Front Arm Ratio was 5:1 however, these Arms were superseded in 1961 or 1962 to types that have the ratio we all have now.

 

I'm confused now.  What ratio do we all have now?  3:1 ?  Certainly the calculation seems to be 5:1 based on your figures.

 

 

 

The photos I've posted here with the ruler and the arm (as I mentioned above) is only a rough guide. As Nick mentioned the 'effective' length of the arm isn't to the Ball Joint Pin Hole, but to the Ball Joint Roll Centre. The photos were to show that it's far closer to 5:1 than is 3:1.

 

 

Interesting quote from the Mini Mania forum suggests the ratio is not the leverage ratio, but doesn't explain how it is determined.

 

"The ratio for lowering the front has been distilled down to a widely acknowledged 3 to 1; i.e. to lower the car an inch and a half, half an inch needs removing from the knuckle joint end of the trumpet (3 x 1/2" = 1-1/2"). However, this ratio is not linear. The more you want to lower the car, the ratio decays slightly, so err on the lesser side of the required amount. If too much is taken off, you will have to strip the whole thing down again and put shim-washers in to get the height back up to where it is required. And incidentally - the 3 to 1 ratio is NOT the actual suspension leverage ratio."

 

The Arm moves through an Arc, so the Ratio actually changes over the entire movement. The average as I've measured is 4.45:1 over 58 points. From memory, the range of the ratio is from 4.42:1 to 4.49:1.