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How does a torsion bar suspension work?


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#51 Fat Boy

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Posted 08 July 2019 - 23:35

just guessing here, but I wonder if the relativities between Monroe and Bilstein would have (not) appreciably changed over the period?

 

Honestly, the Monroes were shite from day 1. Way too much rebound, specifically in the rear. It was just the valving.



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#52 Fat Boy

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Posted 08 July 2019 - 23:36

Side note, I'm presently working on a car that has a ton of front anti-dive, of which I've never been a fan. It's brilliant. Live/learn. I still don't like anti-squat.


Edited by Fat Boy, 08 July 2019 - 23:37.


#53 Fat Boy

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Posted 09 July 2019 - 16:40

I don't, and I'd have thought Tim would be much more helpful than me on the track stuff, but as a first question what exactly can you adjust? Did they include graphs? Once upon a time John Miles measured the front shocks on a whole bunch of B class cars (Fiesta etc). He then overlaid the graphs after scaling them for motion ratio. If you crudely linearise the curve as a low speed bit and then a high speed compression and high speed rebound, he found that the ratio of the two high speed parts varied wildly from about equal, to 4 times as much rebound as compression. His private conclusion was that nobody in the 90s really knew what they were doing, in the paper he wrote he just said that shock tuning is a difficult compromise, assuming that all the development engineers were competent.

 

Milliken includes a brief section on dampers for racecars, I don't have it to hand but I can dig that out.

 

The compression/rebound split is a big deal in terms of feel and grip. Rebound is often used because it's easy to feel. Moderate changes have meaninful ride, response and handling. Because of this fact, it's almost always overused in my opinion. Designating a spring, then winding in the rebound bleeds until you're happy is a lot easier than holding rebound damping constant while testing the trade-offs between compression damping and spring rate. Really nailing the trade-offs between grip/response on the compression side is difficult to do well, but makes for a much better overall product. I've never had success with a heavily rebound-stiff car unless it was a spec damper with little/no adjustability.



#54 Fat Boy

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Posted 09 July 2019 - 16:47

That conclusion rests on the assumption that Bilstein shocks from 15 years ago were as good as they are now, AND that the 15 year old Monroes didn't degrade over time. Neither is likely.

 

As if I've never tested a bloody damper. C'mon. Even if we give the Monroes every benefit of the doubt, I'm talking about how they're valved, not the build quality or technology inside. The Monroes felt very similar to the stock damper (which I didn't like and was getting away from so many years ago in the first place). It turns out they probably just reproduced the same basic force curve as stock.

 

Bilstein seemed to actually try to produce a better than stock valving...and they did.



#55 Greg Locock

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Posted 12 July 2019 - 00:39

I was discussing a new suspension geometry with a drift racer, and he asked me if I thought antidive would help, and in what way. He'd dug up an old post of mine where I was moaning about it. So Fat Boy, what has changed? Is it that the antidive keeps your aero rake constant even with softer springs? That was my guess.



#56 kikiturbo2

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Posted 12 July 2019 - 17:40

I was discussing a new suspension geometry with a drift racer, and he asked me if I thought antidive would help, and in what way. He'd dug up an old post of mine where I was moaning about it. So Fat Boy, what has changed? Is it that the antidive keeps your aero rake constant even with softer springs? That was my guess.

I would think that anti dive would be of no use to a drift racer.... they hardly use front brakes in anger..



#57 Greg Locock

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Posted 12 July 2019 - 18:04

Aye, but with a clean sheet design there is no reason not to think about it.



#58 Fat Boy

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Posted 12 July 2019 - 23:02

I was discussing a new suspension geometry with a drift racer, and he asked me if I thought antidive would help, and in what way. He'd dug up an old post of mine where I was moaning about it. So Fat Boy, what has changed? Is it that the antidive keeps your aero rake constant even with softer springs? That was my guess.

 

I'm not exactly sure. All I know is this car doesn't seem to have any of the issues you might suspect with a lot of 'anti's'. The suspension manual claims 66.3% front anti-dive and 91.6% rear anti-lift. It does a hell of a good job of controlling the aero platform (an aero-dominant car). The car has no provisions to change suspension geometry and I have no wish to. It's nice when the factory can get that bit right.



#59 Fat Boy

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Posted 12 July 2019 - 23:07

Also, I'm not running this car particularly soft. It's 4-4.5 Hz on the front without bump rubbers or the 3rd engaged.



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#60 Greg Locock

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Posted 13 July 2019 - 03:32

Bumpy!



#61 Lee Nicolle

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Posted 18 July 2019 - 08:18

Road car shocks are so totally diverse as to be rediculous.

Once put some Bilstien gas shocks into the rear of a Commodore,, it was undriveable as the gas pressure was obviously way too much. On other vehicles gas pressure shocks lifted and firmed the ride which was excellent. 

I have fitted 'off road shocks' to 4wds and some are excellent and others useless, either to stiff or soft and floaty. And again  both good brands as well as cheapies too

Back at the start of HQ Racing they used Bilstiens  as the contro shock which obviously had a problem as when the rear got sideways the wheels danced big time. The Pedders used now do not do that.

Using Gabriel shocks in my Ford Galaxie they were stuffed in 10000km. Now the thing has some used Pedders gas shocks in the rear from the Falcon racecar and some 7 rate basic AFCO steel body street stock shocks. All of which are a vast improvement.

And the racecar has got some 'Pro Shocks' built by Wayne Randall for the car and while hardly ideal they are a LOT more supple than the stiff road car shocks previously installed. And a LOT cheaper than many so called race shocks.

Had a Gabriel 'top out' in the Super Mod, that was junked also. Now I use all proper speedway shocks though had one give up and it had the wheels really dancing while going quite slowly. The track was poor. Though that shock probably leaked the oil out. It had sat for quite a while.

 I now before every meeting disconnect the top of the shock and feel them to make sure they are ok.



#62 Lee Nicolle

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Posted 18 July 2019 - 08:22

I was discussing a new suspension geometry with a drift racer, and he asked me if I thought antidive would help, and in what way. He'd dug up an old post of mine where I was moaning about it. So Fat Boy, what has changed? Is it that the antidive keeps your aero rake constant even with softer springs? That was my guess.

Drifters do not need aero. They want the car unhooked, especially in the rear. The wings are to look fast and nothing else.

They still need shock control though ofcourse, the last thing they want is the wheels either end dancing when driving sideways with the tyres smoking.



#63 gruntguru

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Posted Yesterday, 04:05

Success in the sport of "Drifting" requires tyre smoke and cornering speed. Anything that improves grip (including aero) is a benefit.



#64 Fat Boy

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Posted Yesterday, 22:28

Success in the sport of "Drifting" requires tyre smoke and cornering speed. Anything that improves grip (including aero) is a benefit.

 

The ones I'm familiar with have plenty of smoke. Some of it's even from the tires.

 

When I've watched them, they seem to have quite a bit of legitimate understeer, but massive HP and a hand brake to put the car sideways. They also have a _ton_ of steering lock available.



#65 Fat Boy

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Posted Yesterday, 22:32

Road car shocks are so totally diverse as to be ridiculous.

 

I took my son to a monster truck show. I wanted to go to the back and do a couple re-valves for some of the guys just to make it fair. Gravedigger might as well been driving on a feather bed.

 

 

I just find it funny how I missed the blatantly bloody obvious about my own truck.



#66 Greg Locock

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Posted Yesterday, 23:34

70 degree lock angle, 700 hp+, various arguments about wheelbase and MoI .

 

No mention of aero, so far. I'll toss it into the conversation this week.



#67 Fat Boy

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Posted Today, 15:41

70 degree lock angle, 700 hp+, various arguments about wheelbase and MoI .

 

No mention of aero, so far. I'll toss it into the conversation this week.

 

I think CG placement/ballasting could be a big variable to investigate. On the aero side, I would look more at a large rudder piece to straighten the car (like an LMP car). Downforce in general will make the car less linear to drive, but I think increasing the inherent stability(not necessarily more understeer) in the car would allow the driver to induce more instability without getting in trouble.