Hydrolastic : Poor Handling

[Andrew1967]

I presume the struts on the rear are the same length ? There are two different lengths .

[111Robin]

I presume the struts on the rear are the same length ? There are two different lengths .

They were the original struts Andrew so I'm assuming both the same. Something i can try to measure on the car though.

[mk1coopers]

Having a hydro car the biggest improvement was from fitting adjustable shocks on the front, from there you can start adding things like competition bump stops / rear ARB's depending on how far you want to go, playing with tyre pressures may also help to tune the feel to your preference

[111Robin]

Actually I forgot that I replaced one helper spring with a NOS item. Although the same type as the original I didn't think to check the spring rate compared with the original. If one spring has a higher rate, I'm assuming this means a higher pressure required to achieve the same wing height as the opposite side. This would result in the same side front corner sitting higher due to the higher pressure. I could try swapping the spring around to see if the discrepancy also swaps around. Sound feasible ?

[Peter Laidler]

I'm trying to think of an easy or simple way of testing the spring poundage while they are ON the car........! But thinking on my feet, if the front ride heights were identical then a 'stretched' or weaker helper spring would show up by the slightly higher rim-to-wheel arch flange measurement over the 'stronger' side. But changing round the springs...., what a PITA. Tanks out, suspension down and......... Phew!

[111Robin]

I'm trying to think of an easy or simple way of testing the spring poundage while they are ON the car........! But thinking on my feet, if the front ride heights were identical then a 'stretched' or weaker helper spring would show up by the slightly higher rim-to-wheel arch flange measurement over the 'stronger' side. But changing round the springs...., what a PITA. Tanks out, suspension down and......... Phew!

I'm getting almost 1/2" difference Peter, if I set it even at the front. Unfortunately the pressure gauge on the pump is burst so I can't tell if there's a significant pressure difference between each side. I agree, not an easy swap so I'll continue to investigate before deciding what to do.

[carbon]

Actually I forgot that I replaced one helper spring with a NOS item. Although the same type as the original I didn't think to check the spring rate compared with the original. If one spring has a higher rate, I'm assuming this means a higher pressure required to achieve the same wing height as the opposite side. This would result in the same side front corner sitting higher due to the higher pressure. I could try swapping the spring around to see if the discrepancy also swaps around. Sound feasible ?

The helper springs should have a coloured plastic sleeve. From memory:
- black sleeve is earlier helper spring
- orange sleeve is later helper spring
I believe the orange is stiffer than black, others may be able to confirm. But I don't think this would cause the condition you have described with the uncertain handling?

[111Robin]

Actually I forgot that I replaced one helper spring with a NOS item. Although the same type as the original I didn't think to check the spring rate compared with the original. If one spring has a higher rate, I'm assuming this means a higher pressure required to achieve the same wing height as the opposite side. This would result in the same side front corner sitting higher due to the higher pressure. I could try swapping the spring around to see if the discrepancy also swaps around. Sound feasible ?

The helper springs should have a coloured plastic sleeve. From memory:
- black sleeve is earlier helper spring
- orange sleeve is later helper spring
I believe the orange is stiffer than black, others may be able to confirm. But I don't think this would cause the condition you have described with the uncertain handling?

Yes not so much the handling directly, but I'm trying to figure out why it can't be set level front and rear, this may be contributing to the handling not being as it should.

[1071 S]

If you mean level front to rear ????

They aren't; the back should sit about 13mm (1/2 inch) higher than the front....

One of Aus' top Mini racers from way back when once told me he jacked the back of his car up a couple on inches to loosen up the back end.... (an admirable trait IHO).

"......Actually I forgot that I replaced one helper spring with a NOS item. Although the same type as the original I didn't think to check the spring rate compared with the original. If one spring has a higher rate, I'm assuming this means a higher pressure required to achieve the same wing height as the opposite side. This would result in the same side front corner sitting higher due to the higher pressure. I could try swapping the spring around to see if the discrepancy also swaps around. Sound feasible ?..."

Is this not back to front? The spring counteracts the gravity pulling the opposite end down (no spring means the front sits on the bump stops). So more spring at the rear will lift the front up ..so less pressure is needed to drop it down ... which means the rear drops as well and the spring rate reduces.... so.......

Cheers, Ian

[111Robin]

If you mean level front to rear ????

They aren't; the back should sit about 13mm (1/2 inch) higher than the front....

One of Aus' top Mini racers from way back when once told me he jacked the back of his car up a couple on inches to loosen up the back end.... (an admirable trait IHO).

"......Actually I forgot that I replaced one helper spring with a NOS item. Although the same type as the original I didn't think to check the spring rate compared with the original. If one spring has a higher rate, I'm assuming this means a higher pressure required to achieve the same wing height as the opposite side. This would result in the same side front corner sitting higher due to the higher pressure. I could try swapping the spring around to see if the discrepancy also swaps around. Sound feasible ?..."

Is this not back to front? The spring counteracts the gravity pulling the opposite end down (no spring means the front sits on the bump stops). So more spring at the rear will lift the front up ..so less pressure is needed to drop it down ... which means the rear drops as well and the spring rate reduces.... so.......

Cheers, Ian

I'm talking about level across the car not front to rear. I know the trim height is higher at the rear. When i adjust each side so it sits level at the rear, one front corner is 1/2" higher than the other front. Conversely when set level at the front one rear corner is 1/2" higher than the other rear. Therefore one corner has a mechanical discrepancy, i need to determine which corner then rectify the issue. Identifying the rogue component won't be easy.

[Peter Laidler]

Mine has been set up, suspension up and down more times than a whores draws, disassembled, rebuilt a zillion times over the past 2 years or so and while the front of the car is level, the rear heights differ by, probably getting up to 1/2" or so. I also found out that what BMC and the wksp manual say in THEORY regarding the rear SFrame and alignment doesn't equate to the practice.

[111Robin]

Mine has been set up, suspension up and down more times than a whores draws, disassembled, rebuilt a zillion times over the past 2 years or so and while the front of the car is level, the rear heights differ by, probably getting up to 1/2" or so. I also found out that what BMC and the wksp manual say in THEORY regarding the rear SFrame and alignment doesn't equate to the practice.

That's interesting Peter, maybe it's down to component tolerances. Perhaps the only option is to adjust out the discrepancy by altering one of the rear strut lengths.

[111Robin]

Depressurised and pumped up each side twice, just a longshot, didn't make any difference. Nothing is out of place so it must be down to a dimensional discrepancy in a component or several components. I'll just leave it as is, no point stripping it without knowing what the problem is. Regarding the handling, I'm running on Regal tyres, does anyone else use them and can report on how they affect handling ?. I may consider a set of Blockleys if they would improve handling.

[carbon]

I thought the Regal 145x10 was a trailer tyre?

I'm running with 145x10 Falken Sincera on 4.5 rims, this gives very predictable handling.

[111Robin]

I thought the Regal 145x10 was a trailer tyre?

I'm running with 145x10 Falken Sincera on 4.5 rims, this gives very predictable handling.

Not sure. One of the photos in the recent Beaulieu thread showed a Mk1 (I think) on Regals. Aren't they made by dunlop as a budget line ?.

[111Robin]

A combination of re-trimming the suspension height and adjusting the front track has transformed the handling. Track was actually slightly toe in which obviously wouldn't help. Handling like a dream now (well at least a "wet" hydrolastic dream!!). It'll be driven a lot more this summer now that's for sure.

[1071 S]

Glad to hear my "helpful" suggestion eventually came good

Cheers, Ian

PS I couldn't help myself

[111Robin]

Glad to hear my "helpful" suggestion eventually came good

Cheers, Ian

PS I couldn't help myself

I've reset the heights and track a couple of times since the rebuild so it's something I do myself anyway, i just didn't expect it to be toe in as i set it perfectly last time. It's obviously very sensitive to height changes.

[carbon]

Robin,

Sounds like good progress.

Can I ask if the Regals are radial or crossply tyres?

[111Robin]

Robin,

Sounds like good progress.

Can I ask if the Regals are radial or crossply tyres?

They're radials, 145/80. They generate a lot of road noise, I'll need to try out a different tyre to see if it improves the overall handling.