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Post by Roy of the Rovers on Sept 3, 2015 15:14:38 GMT
Hi all. I've been looking to reduce the body roll on my P5 for a while. I did replace the very old and rusty standard shocks with nice new Adjustable shock absorbers. They have certainly stiffened the ride but now give a pretty bumpy ride on the dodgy roads around here in Sussex. What I'm more looking for is a less bumpy ride but a more sure footed cornering ability and I have found a fairly local well known company who will custom make a stronger anti roll bar for me. Now when it comes to the springyness of steel I know absolutely squat, so I'd be tempted to ask them for at least a 50% increase in spring resistance over standard, maybe double. Do any of you learned fellows have an opinion or can recommend a stiffness of roll bar? (Other than its fine as it is.. because it is far from fine as it is ) I'm looking to be able to back off the shock settings on the front (and so bring back the relaxed cruising the car has without the bumpy ride) but know that the car will be sure footed at speed on twisty roads, and eventually do a few track days at Goodwood which is just down the road. Those would be few and far between though. Heres a picture from last weekend, the twisty roads are in the background and known as the South Downs Attachment Deleted
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Post by Steve P5b on Sept 3, 2015 18:45:38 GMT
A well proven and simple method of correcting lots of roll is to get yourself a roll bar from the same car and clamp it to the existing bar with some suitably fabricated clamps( or try rally design). There is no need to attach it at the ends but make sure the existing rubbers are in tip top condition If you find things too much then shorten the additional bar progressively until your happy. Fitting one to the rear is where I think mine needs doing but haven't got it sorted yet. Post some pictures of your progress Roy it'll be interesting.
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Post by petrolhead allan on Sept 3, 2015 18:46:44 GMT
Last year, I was in email communication with Jon Wadhams about making a stiffer anti-roll bar for my P5B. He said he sells a lot of them for P4's and felt that one for a P5 should have a good demand. He was going to investigate the production, using his supplier of P4 bars, and my car would be the test mule.
Unfortunately, things changes at the forge he uses, and his usual contact left the business. Due to other business commitments, Jon decided not to try and pursue the project any further. The main problem with the P5 bar is the 3-dimensional shape (not just a flat bar with a bend at each end) which a lot of spring firms are shy about tackling.
I did a lot of Googling about front anti-roll bars, and my conclusion was that a 50% increase in stiffness would be a good starting point. The very real drawback of having one too stiff is that the inside front wheel will tend to be lifted by the outer front wheel when cornering, causing loss of grip and considerable understeer.
So, that would have been my suggestion, but I have to make clear that this is an opinion only! I would recommend that you do a spot of Googling on the subject to gain some insight into the theory and practice.
Having said all that, if you have found a firm who will make a stiffer anti-roll bar, I'd be very interested also, so please keep us all updated.
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Post by petrolhead allan on Sept 3, 2015 19:00:39 GMT
Jon Wadhams and I were also looking at reinforcing the anti-roll bar mountings. He had sourced a larger bush and clamp for the subframe mounts, and I was thinking about larger diameter drop links on to the front suspension.
I thought about using part of a second standard bar as Steve P5B suggests, but felt it was a bit 'inelegant,' but maybe it would be a less expensive option, and also allow for fine tuning. I still think stronger mountings would be advisable, and the means of connecting the two bars (double-clamps?) needs some careful thought; probably a job for an engineering shop because I suspect that they would take a lot of stress.
That makes me think about my other reason for not pursuing the idea of a second bar: all the additional stress would be placed upon the ends of the original bar. I'm no engineer, but would that be good practice? I would think that a complete, one-piece stiffer bar would be the better option.
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Post by Roy of the Rovers on Sept 3, 2015 20:40:38 GMT
Thanks for input chaps. I have considered the double bar before as it would certainly be the cheaper option. But as you say its quite obvious underneath and a thicker bar is my preferred option. I have a company that would make a single thicker bar and with suitable heavy duty tie rods and poly bushes it should be good for the job. I have asked about cheaper per unit for a multiple order so lets see. Ive left a message for Dave G to see how much a spare bar and mounts would be to save removing mine. As soon as i get one ill take it with me and get it priced up. If anyone else has opinions please feel free to add? Any aussies?
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Post by djm16 on Sept 5, 2015 5:12:59 GMT
I am assuming that what are commonly referred to as "shocks" in your case are actually dampers and not coil-over springs over dampers. In which case the following applies:
1) If set to dampen too little, then an undulating road can cause a vertical up and down resonance to set in at about 30-60 beats per minute. A car equivalent of a tank slapper.
2) If set to dampen too much, then at high frequencies you are essentially running on a rigid suspension system where minor bumps are transmitted direct from the road to the chassis with only the tyres cushioning the blows. This is lousy for road holding, uncomfortable and bad for tyres and chassis.
Set right, the chassis remains level as you go over a series of bumps with little transmission of road variations to the chassis and no sympathetic oscillation either.
It sounds to me as though you have your dampers set way too hard. Simply adding an upgraded sway bar will make the ride even more painful.
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Post by Roy of the Rovers on Sept 7, 2015 8:28:41 GMT
Hi, I think you missed the point a little?The purpose of my post is to reduce 'lean' on cornering. Nothing to do with bumps in a straight line.
The shocks (shock absorbers/dampers same thing) I fitted were simply available and an improvement on my standard ones. I wondered if they might help on cornering by being a little firmer. And as you say, the ride is now harsher up front, so I need to ease off the setting and fit a stronger anti roll bar. Then the car will be firmer and more steady over bumps than standard (the new shocks) and be more predictable and safe around corners (the anti roll bar).
I'm looking for suggestions on how much to increase anti roll bar stiffness by if anyone has experience of this? Otherwise I will request 50% I think and see what I get.
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Post by enigmas on Sept 7, 2015 13:04:20 GMT
Roy I bent up a one off spring steel sway bar for my coupe then had it retempered at a spring works about 20 years ago. IIRC the bar is 3/4" diameter.
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Post by Roy of the Rovers on Sept 8, 2015 10:02:43 GMT
I think thats right, around 20mm. Now I've replaceed the tie rods and bushes on mine with polyurethane it should be easy to take off and go and visit the company in a couple of weeks time.
I was really hoping to have a spare handy so as not to disable to car, but no one seems to have one knocking around..
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Post by enigmas on Sept 8, 2015 11:11:55 GMT
You can drive the car without the anti roll bar fitted. The suspension is a 1950s design so it really is an add on.
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Post by Roy of the Rovers on Sept 8, 2015 13:37:28 GMT
Ha! I don't think I would want to try that... apart from the slogan "Its never over in a Rover " I don't think I would want to drive it like that.. or to explain it to the insurance company when my car gets pulled out of the ditch All joking aside, I know what you mean Vince but I think the authorities would take a dim view over here if anything happened. I'll do it in a few weeks time and leave her in the garage..
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Post by enigmas on Sept 8, 2015 22:08:19 GMT
I'm not joking guys. I don't think either of you are about to drive the car at the limits of adhesion or test it on the twisty bits in your neighbourhood! The original bar at 1/2" (?) is a very mild option as far as handling is concerned. Fitting radials causes more of a dynamic change to overall handling that was never considered by the designers. Adding a thicker bar for greater roll resistance also changes the dynamics of the car but in the end only do what makes you feel comfortable or understand technically.
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Post by djm16 on Sept 8, 2015 23:44:21 GMT
Well partly my reply was for the benefit of others reading now or later who might wonder what a sway bar does. Essentially it has no effect on bumps that hit both front wheels simultaneously, but adds stiffness to the response to a bump that hits only one front wheel.
While a thicker sway bar will reduce lean on cornering (OK on a smooth race track), it is at the cost of impaired road holding over bumps and increased transmission of road conditions to the driver.
For a guess at an appropriate stiffer sway bar you could refer to the Dia of a standard P4 sway bar and the upgraded sway bar sold by Wadhams (I do not have those values to hand but I am sure others do somewhere).
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Post by Warwick on Sept 9, 2015 3:39:01 GMT
Slightly off topic, but I always thought that Nissan's solution for their Patrol was a good one, after they changed from leaf springs to coils by copying the Range Rover's suspension. The Range Rover had no anti-roll bars, and very soft long-travel suspension, so they lean dramatically on corners. Adding anti-roll bars to fix this would have severely limited their off-road ability by restricting independent wheel movement. Nissan solved this problem by fitting anti-roll bars that were joined in the middle by a splined sleeve. For normal driving, the sleeve was engaged. For off-road driving it was disengaged.
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Post by enigmas on Sept 9, 2015 6:06:14 GMT
Well done Warwick, you've nailed the function and purpose of 'the bar' with a definitive example.
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Post by Roy of the Rovers on Sept 9, 2015 9:05:52 GMT
Well I'm definitely going to persue this providing an economical bar can be made. I will report back with progress (or otherwise!).
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Post by Warwick on Sept 9, 2015 9:46:50 GMT
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Post by gingerbeer62 on Sept 10, 2015 20:15:17 GMT
I find the best way is to think about the car action on the anti-roll bar (where it's fixed to the body) and not the other way around. Anti-Roll or Sway bars mechanically are basically a lever and controlled twist of a bar (ie spring) and are only designed to assist in controlling vehicle roll or sway when the vehicle is cornering. Obviously, centrifugal force is set up as the vehicle is forced around in a circle and the inside tends to lift and the outside go down. So, drivers side is resisted as the twist and lever of roll bar (due to shape) tends to pull the body back down and the oposite on the other side of the body. Hence, the stiffer the bar, the more force is exerted. Bumps are not really relevant to the bar as when the vehicle hits a bump on one side the wheel goes up and due to the force transmitted to the other side via the bar, tends to lift that side as well. Not the best as both wheels are "tending" to lift off the ground. So not much help on rough ground. In fact if the bar was so stiff as to not flex at all, the other wheel would be tended to be forced/lifted off the ground as well ! In the case of both wheels hitting say, a speed bump, both wheels go up and and no effect is felt as the bar "pivots" in it's rubber mounts. So, a stiffer bar would be advantageous in controlling roll, would make the one bump scenario worse and the speed bump scenario - no change or effect - it would still pivot as before. So, if the bar was taken off altogether, the only thing that would be affected would be roll or sway. It would turn your Rover into an early Range Rover Plenty of cars didn't have them and the only thing is the MOT rule "if it's fitted, it has to work" However if you took it off altogether maybe MOT would be OK. Although all evidence would have to be removed from the car. A bit like if you remove your spare wheel before an MOT it does not come into it. If it's there, it has to be legal.
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Post by harvey on Sept 25, 2015 13:25:32 GMT
A bit like if you remove your spare wheel before an MOT it does not come into it. If it's there, it has to be legal. View AttachmentNot true, the spare doesn't come into the test, bit if it's illegal and you leave the test centre with your new MOT you can get nicked for it as soon as you leave. From the Tester's Manual. "This inspection applies to tyres fitted to the road wheels only. The vehicle presenter should be informed when it is noticed that there is a defective tyre on a spare wheel"
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Post by stantondavies on Oct 3, 2015 22:20:42 GMT
I am puzzled as to why there is a problem with body roll; I have never suffered any problem despite my spirited driving. What tyres are you using?
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Post by Roy of the Rovers on Oct 8, 2015 14:32:31 GMT
I am puzzled as to why there is a problem with body roll; I have never suffered any problem despite my spirited driving. What tyres are you using? Its more the evolution of the journey I have been down to get a better handling car, but at the expense of a harsh ride. I have wider tyres (better grip), I have lowered the front torsion bar settings (more sure footed feel through the wheel) and finally I have replaced my worn dampers with adjustables (reduced body roll)... But this has finally ended up with a bumpy ride. As a result I'm taking a step back and trying to get a stiffer anti roll bar, which will allow softer Damper settings and bring back the smoother ride, but crucially it will reduce the body roll in the corners. If it's cost effective it will allow people who are conscious of originality to have a better handling car with no noticeable modifications. Thats the theory anyway. I'm hoping to see the manufacturer tomorrow and if it results in a test piece then I will take some cornering shots at a set speed to see what difference it makes. Watch this space.
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Post by stantondavies on Oct 8, 2015 19:32:13 GMT
Rover had a cadre of engineers devoted to developing their cars and it will be difficult for you to continue with their work other than by your trial and error. My approach is to leave well alone unless there is a pressing need for a modification, so I am no help! Have you studied what Rover did to their rally cars? It might provide help in improving the handling and ride of your car. Good luck.
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Post by enigmas on Oct 8, 2015 22:50:25 GMT
Roy you're a brave man discussing your desire and actions to improve the handling of your coupe in such an open fashion. There's a lot you can do that is virtually invisible if that's your aim. Engineers working in tandem with accountants don't always get it right, as can be seen with the (Palmer designed) MG/Wolseley sedans of the 1950s in relation to the later Farina versions. This is evident in apparently retrograde changes made to the basic platform/chassis such as replacing the precise rack and pinion steering with vague worm and peg with it's multitude of steering linkages.
If you are truly serious about upgrading the handling you really need to look at the subframe mounts (OMG) and ensure that there is absolutely no relative movement between the subframe and the main body, otherwise all your other mods to the front suspension are discounted. (Check out the thread in the Modified section...the car's ride quality is unaffected and the steering is marginally improved for obvious reasons)
The car is a 1950s design and from that stance it handles fine against vehicles of the day for owners that are content with that.
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Post by Roy of the Rovers on Oct 9, 2015 8:42:54 GMT
The car is a 1950s design and from that stance it handles fine against vehicles of the day for owners that are content with that. Roy of the Rovers = Not content with that (but not looking for a race car either) Just looking at comfort and body roll on a budget.
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Post by Phil Nottingham on Oct 11, 2015 21:41:12 GMT
The front heavier P5 does understeer and roll more than the P5B - its anti-roll bar is also straight ie without the kinks needed to clear the V8 engine so would be a lot easier to make thicker
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