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09-12-2005, 11:13 PM | #31 | |||
Tickford Rules!
Join Date: Jun 2005
Location: Australia
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FWIW, I'd say the AU, as a pure double wishbone set up, is technically a better design than the control blade IRS. But it was a little heavy. Control Blade is almost as good, and lighter, hence its adoption in the BA series.
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Thanks for setting the record straight.
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Tickford Rules! :eclipsee_ 1969 Ford Fairmont XW 1999 AU I Falcon XR6HP 1999 AU I Falcon XR8 (sold) 2007 Mitsubishi Evolution IX 2009 Lotus Elise S |
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09-12-2005, 11:34 PM | #32 | ||
Right out sideways
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When BA 1st came out i remember reading a few articles saying the AU's IRS had better communication as to where its going
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10-12-2005, 12:03 AM | #33 | |||
FF.Com.Au Hardcore
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PS the weight difference between the live axle and the Double wishbone AU assemblies is 80kg. I dont know the difference between the live-axle in the BA/BF and the Control Blade. I too would guestimate about 50-60kgs. ie saving of 20-30kg between the two IRS setups. |
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10-12-2005, 12:46 AM | #34 | |||
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Always new you would come up with all the facts. LOL Your an encyclopedia an AU's Alan |
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10-12-2005, 01:44 AM | #35 | |||
T3/Sprint8
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Tickfords T3/TS50 '02 Sprint8 manual Sept 24 '16 Daily Macan GTS "Don't believe everything you read on the internet. Abraham Lincoln" |
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10-12-2005, 09:34 AM | #36 | ||
Regular Member
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I haven't driven an IRS-suspended AU, nor a BA, with a view to comparing their handing or grip thresholds...so my comments are based on what I have read.
The AU IRS setup is a classic double wishbone IRS. Design-wise there is absolutely nothing wrong with it at all. It has all the advantages and disadvantages of that design. The double wishbone design has been around for 50+ years, and it gives excellent control over toe and camber as the suspension compresses due to bumps and body roll. This means that the tyre tread stays nearly parallel with the road surface as the suspension moves through its full range of travel. The tyre gives the most grip when its tread is parallel with the road surface. And of course the tyre wears evenly across the tread. Hence the AU IRS was well known for giving excellent handling and excellent grip. It is a premium IRS. Disadvantages? As some have mentioned it is heavier than the live axle, and chews out the upper mounts. Design-wise, with double wishbones there is the ride-handling compromise. The tight control over the suspension as it moves means that there is little 'give' in the suspension. Control results in good handling, 'give' results in a good ride. Few people on this forum would complain about good handling... With double wishbone IRS, the engineers can choose the spring rates and bush compliance to give fantastic handling, or a superb ride - but not both at the same time. Of course the engineers can choose to mix reasonable handling with a reasonable ride. I remember most reviews of the AU Fairlane praising the handling, and a few reviews complaining about a jiggly ride. So we could conclude that the good handling of the AU IRS cars came at the expense of ride quality. The 'control blade' IRS design used in the BA and Territory is a new design originally developed by Ford engineers in Europe (I think). It was first used on the Focus Mk1, and is suitable for small FWD cars as well as large RWD and AWD cars. Control blade IRS is a step forward from double wishbone IRS because it allows for an excellent ride while giving excellent handling. So the engineers are less constrained by the ride-handling compromise. Control blade IRS achieves a better ride while giving the same good handling as a double wishbone IRS. Technically speaking, control blade de-couples the vertical and lateral forces on the rear suspension. The design allows for compliance when the wheel moves vertically - this means that the ride is good. However - and this is the key point - the compliance in the vertical motion doesn't result in loss of control over toe and camber. In other words, the tyre tread stays parallel with the road surface as the suspension compresses, giving good handing as with double wishbones, but there is also vertical compliance so the bumps are better absorbed, so the ride is better too. With double wishbones, tight control over toe and camber comes at the cost of compliance with vertical movement. I think this is the main difference between these two IRS systems. All BA reviews that I have read praise the fantastic ride, even in the sport models. And BAs are universally praised for their excellent handling and rear-end grip. So it looks like the Ford Oz engineers made the most of the potential that control blade offers. |
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10-12-2005, 11:15 AM | #37 | ||
Ute Forum Moderator
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Sorry for the slightly off-topic question (now that the original has been answered) but earlier it was mentioned that you could stick AU irs in an XE-EL - has anyone actually seen this done?
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10-12-2005, 11:21 AM | #38 | ||
windsor user
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Location: Geelong
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i havent, but i have gone over the whole rear of both cars with a measureing tape, as well as checking out the cut-away setup they have at the ford discovery center...
the setup has its own "cradle", which mounts to the chassis. the front mounts attach to the factory front lower arm mounts, and for the rear you have to remove the brackets off the chassis and weld them into the earlier "rails". the shocks mount in the same shocker mounting position i believe the only thing keeping me from doing it is a) you'd just about have to get an engineers certificate, and B) i simply cant afford to at the moment... but it would definatley be something i'd love to do in the future.... |
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10-12-2005, 02:58 PM | #39 | ||
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I'd like to know if an AU IRS can be retrofitted to any of the leaf spring models, and what would be involved?
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10-12-2005, 05:08 PM | #40 | ||
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would be a LOT more involved as you need the existing lower arm mounts as in the XE-EL
it'd just about require a half floor graft or something like that.......a lot of work id guess |
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10-12-2005, 05:23 PM | #41 | |||
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Tickfords T3/TS50 '02 Sprint8 manual Sept 24 '16 Daily Macan GTS "Don't believe everything you read on the internet. Abraham Lincoln" |
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10-12-2005, 09:30 PM | #42 | ||
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I have raced both AU & BA with IRS at the drags & on track days & theres not much in it. The AU is a wisker better, it hooks up better at the drags, & also gives better drive on the track. I think the BA is a tad more heavy from what I can remember..
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10-12-2005, 10:49 PM | #43 | |||
Tickford Rules!
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Yeah, this makes sense to me. I still think the double wishbone is a 'purer' design.
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Tickford Rules! :eclipsee_ 1969 Ford Fairmont XW 1999 AU I Falcon XR6HP 1999 AU I Falcon XR8 (sold) 2007 Mitsubishi Evolution IX 2009 Lotus Elise S |
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11-12-2005, 09:50 AM | #44 | |||
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MADNC_8: I don't suppose you have measured up any of the leaf spring cars? What do you think? It would be a lot easier and cheaper to fabricate and fit a cradle than it would be to cut and replace the rear floor, wouldn't it? If there was room for the cradle, that is. Ford used this 'cradle' idea to allow the IRS to be fitted to the body of the Watts link cars, without requiring body modifications. So the cradle concept provides enough strength and durability if done properly. |
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11-12-2005, 07:00 PM | #45 | ||
Ute Forum Moderator
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Cradle aka subframe, the Jag irs uses the same idea, has gone into heaps of hot rods. Modding the subframe is a good idea, as you already have 4 mounting points from the leaf springs, they are just in a different location from the Watts linkage mounts.
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11-12-2005, 07:14 PM | #46 | |||
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11-12-2005, 11:33 PM | #47 | ||
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It is mounted via rubber bushes, it is designed to have a bit of compliance for nvh reasons, very similar to engine mounts really
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12-12-2005, 09:55 AM | #48 | ||
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Thanks for the info guys. Great stuff. Went for a run yesterday with a mate who owns an AUIII XR6 VCT (very nice machine) out to Blackwood then through Trentham and Woodend. Nice roads to test out the IRS, especially the run up the hill from Greendale to Blackwood.
I travelled behind the XR6 because (a) it's damn quick around the bends and the V8 really needs to wind up before it can catch it, and (b) I wanted to get a good look at the IRS in action. I must say I was more than impressed with seeing the IRS in action. My mate hardly used his brakes at all, and seeing the suspension grip and pull the car through corners was quite amazing - the back wheels just seemed to grab the road, the back end "lowered" itself a bit and off it went powering out through the corners. Well done Tickford. |
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12-12-2005, 11:52 AM | #49 | ||
Ute Forum Moderator
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Here is a pic of the AU IRS from the Discovery Centre yesterday
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12-12-2005, 12:22 PM | #50 | ||
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Sorry to keep this thread off the original topic, which was how well the AU IRS works.
Great photo, outback_ute. Thanks, it shows the configuration very clearly. No wonder it's heavy! Those wishbones look like they could take a lot of abuse. Cast iron was used for cost control reasons, apparently. Looks like there are only four mounting points - the two at the front, which mate to the existing lower control arm mounts in Watts link cars, and the two top mounts. Re: subframe movement. The bushes between the subframe and the body would have to be pretty strong to control fore-aft and lateral forces. I wonder just how much compliance there is? Does anyone make polyurethane bushes for the IRS subframe? There would probably be a lot more NVH with harder bushes though. |
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12-12-2005, 05:03 PM | #51 | |||
windsor user
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13-12-2005, 02:02 PM | #52 | |||
FF.Com.Au Hardcore
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Good news for me. I'm planning on finding a written off AU XR6 or similar and get the engine/gearbox out of it. If that's the case, I might just get the whole rear setup as well if it's undamaged and it could be worked in there, anyone know if that would be possible?Also, how much that would roughly cost (XR6 engine, gearbox, IRS setups, diff etc)? |
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13-12-2005, 02:10 PM | #53 | |||
Built Ford Tough
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13-12-2005, 02:24 PM | #54 | ||
Tickford Rules!
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Yes, well, ok!
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Tickford Rules! :eclipsee_ 1969 Ford Fairmont XW 1999 AU I Falcon XR6HP 1999 AU I Falcon XR8 (sold) 2007 Mitsubishi Evolution IX 2009 Lotus Elise S |
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14-12-2005, 03:08 AM | #55 | ||
FF.Com.Au Hardcore
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my AU1 Fairlane ghia 6 cyl with VCT has traction control and IRS but no LSD sadly!!
would love to get 1 fitted tho and if it would screw with my traction control.. |
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14-12-2005, 03:11 AM | #56 | |||
Ich bin ein auslander
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14-12-2005, 03:19 AM | #57 | ||
FF.Com.Au Hardcore
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cheers gecko
any idea how much an LSD conversion will cost me? im guessin in the 600-800 mark? |
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14-12-2005, 08:46 AM | #58 | ||
Ich bin ein auslander
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Not really sure, I would thik that would be pretty close to the money. Time to give your favourite diff specialist a call. Certainly a worthwhile mod.
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14-12-2005, 09:17 AM | #59 | |||
Cobblers!
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I remember looking at a BAII XR6 in Manual, and I was told that to get traction control I had to get an Automatic.
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14-12-2005, 01:47 PM | #60 | |||
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