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Location: Ipswich
Registered: October 2003
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RA28 IRS
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Mon, 01 November 2004 02:54
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Has anyone bothered adapting IRS to an ra28 or similar celica? Why I want to know is thus; if it possible to do so, i have access to all the required hardware from an s13 180sx for next to nothing (ie. $50). Would the cost of this gear make it worthwhile, or am I looking at *thowsands* of $$ just to adapt the rear end to have it fit?
It tempting because of the diff, the rear disks, and, well, its IRS.
Cheers, Matt
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Location: Brisbane
Registered: February 2003
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Re: RA28 IRS
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Mon, 01 November 2004 02:57

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i'd start with a tape measure first as width - apart from fabricating whole new mounting system on the car and/or diff and trailing arms - will be a deciding factor.
it would be interesting to compare weights of all the hardware tho...
cheers,charles.
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Location: Ipswich
Registered: October 2003
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Re: RA28 IRS
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Mon, 01 November 2004 03:04

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Yes, I probably should have started with the tape measure I know may be an excerise in futility, but just looking at the rear end sitting there at a mates place, doing nothing, while I try weigh up hilux/corona/f/g/volvo diff options seemed such a waste.
If I really wanted to do it, I would be able to use everything, i'm fairly sure, even cannibalising the existing mounts etc. on the car itself.
I'll have some reading to do, methinks. Apparently ae86's have been fitted with s13 irs kits in japan before (?).
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Location: Terrigal
Registered: May 2002
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Re: RA28 IRS
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Mon, 01 November 2004 03:09

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I'm very interested to hear how this progresses mmmm IRS RA28.
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Location: Ipswich
Registered: October 2003
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Re: RA28 IRS
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Mon, 01 November 2004 03:12

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Well if people want to help me out (read; hold my hand ) i'm more than happy to investigate on other peoples behalf. Where should I start; measuring disk to disk and taking lots of undercar photos?
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Location: Montrose, VIC
Registered: May 2002
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Re: RA28 IRS
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Mon, 01 November 2004 03:32

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Yeah, take some photos etc., but remember you're likely going to need to cut a big slab of floor out of your car anyway. Still, do it anyway, even if just for the sake of doing it
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Location: Ipswich
Registered: October 2003
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Re: RA28 IRS
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Mon, 01 November 2004 03:34

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Does that mean i'd end up with a celeighty, or a onelica?
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Location: Terrigal
Registered: May 2002
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Re: RA28 IRS
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Mon, 01 November 2004 03:34

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I think the hardest bit would be the subframe section where the diff itself bolts up to. Is the S13 one removable? If so, how close is it to fitting between or around the RA28 chassis rails.
The track width is a concern also as it'd be better if you didn't have to shorten it in anyway. So yeah measure the track width and see if it will all fit under the guards. Maybe some more positive offset wheels will help.
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Location: Ipswich
Registered: October 2003
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Re: RA28 IRS
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Mon, 01 November 2004 03:37

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Righto, mission for tomorrow so far:
Track width
Subframe width
Whether subframe is removable
Location of mounting points
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Location: Terrigal
Registered: May 2002
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Re: RA28 IRS
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Mon, 01 November 2004 03:40

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I have a totally stripped RA28 sitting in my garage specifically for this purpose. - engine conversions, diff conversions, brake upgrades, etc.. Shame you are not closer by as you could use that for testing purposes.
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Location: c'town, NSW
Registered: May 2002
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Re: RA28 IRS
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Mon, 01 November 2004 03:49

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anyone talk to an engineer yet?
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Location: Brisbane
Registered: May 2002
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Re: RA28 IRS
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Mon, 01 November 2004 03:53

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I looked into this years ago, and came to the conclusion the time and money required does not justify the outcome. You're much better off spending the money developing the live axle, which can work perfectly well if you're smart about it. V8 Supercars are live axle, and I don't hear anyone complaining about how badly they handle!
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Location: Ipswich
Registered: October 2003
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Re: RA28 IRS
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Mon, 01 November 2004 03:58

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Just rang an engineer, and the quick guideline he gave me required a complete replciation of the s13 rear end, and full working drawings of the setup.
He said personally, he didn't think it was financially worthwhile, but i'll still take the measurements if anyone is interested?
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Location: South Australia
Registered: July 2002
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Re: RA28 IRS
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Mon, 01 November 2004 03:58

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Hmmm - this is an interesting idea.
V8 supercars are understeerers designed for circuit use only, I wouldn't use them as an example of how to build a general car.
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Location: Brisbane
Registered: May 2002
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Re: RA28 IRS
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Mon, 01 November 2004 04:45

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Granted, but they still go around circuits very fast indeed... I was just making the point that a live axle doesn't have to be a handicap.
Another point I forgot to mention, IRS setups are generally much heavier than a live axle. Expect the weight of your RA28 to increase by up to 100kg.
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Location: Adelaide
Registered: September 2003
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Re: RA28 IRS
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Mon, 01 November 2004 04:50

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Norbie wrote on Mon, 01 November 2004 15:45 | Another point I forgot to mention, IRS setups are generally much heavier than a live axle. Expect the weight of your RA28 to increase by up to 100kg.
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As an example, a Crumpledore IRS weighs in at a little over 140kg complete, disc to disc. That is with an 8" CW&P, so the increase might not be 100kg.
But overall, Norbs is right, the live axle can be made to work pretty well. The IRS would be great in a show car, but the time and costs to do it, get it approved, would far outweigh the real life benefits.
For a cct car, different story.
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Location: Terrigal
Registered: May 2002
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Re: RA28 IRS
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Mon, 01 November 2004 04:55

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Even though the total weight is more, the unsprung weight is less.
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Location: Brisbane
Registered: May 2002
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Re: RA28 IRS
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Mon, 01 November 2004 05:37

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Quite true, which is where most of the benefits of IRS comes from.
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Location: Ipswich
Registered: October 2003
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Re: RA28 IRS
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Mon, 01 November 2004 06:15

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Well, hopefully i'll have photos and measurements tomorrow. The subframe is removable, so i'll have a go at pulling it out to have a good look at it.
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Location: Northwestern Sydney
Registered: August 2002
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Re: RA28 IRS
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Mon, 01 November 2004 06:42

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My guess would be you probably cut the floor out of the rear of the doner car and mesh it in with the Celica rear end and build up the chassis structure to adapt the diff housing. would be good to do and I think often of doing it but as has been mentioned previously a live diff can be setup for less fabrication work.
But don't let me stop you as I'd like to see it done.
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Location: Tassie
Registered: October 2003
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Re: RA28 IRS
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Mon, 01 November 2004 07:33

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At the very least u will get rear disks which will make it safer should u chose to mod the motor. IT was also make it easyer to get past transport.
I'm not toatly sure but it might give more adjustment points to get the best handling from ur car and will make diff changes easyer i'd assume.
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Location: New Zealand
Registered: May 2002
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Location: Ipswich
Registered: October 2003
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Re: RA28 IRS
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Mon, 01 November 2004 09:20

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Purple_Beasty, how did you go for engineering? Did this eventually become a road going vehicle?
Also, how did you work out how much to cut out of the floor of the donor and recipient cars? Is it harder to simply replicate the original mounting geometry on the recipient car?
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Location: New Zealand
Registered: May 2002
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Re: RA28 IRS
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Mon, 01 November 2004 09:47

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A few differences, car is going to be fully caged and is being engineered in NZ. The certifier was much happier with me using the factory Carina floorpan as its strength is already known.
We had the complete car, and cut as much as we needed to keep all the mounting points, chassis rails etc. The Starlet is a much smaller car so we then just trimmed the excess to fit. Used the rail across the front of the rear seat from both cars to get it all lined up straight, pushed the wheelbase back 4 inches as well.
Project is currently on hold with the floorpan and new gaurds tacked into place. Just bought a new house, selling the old one and need to build a new shed and get some cash together to carry on.
Callum
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Location: Newcastle
Registered: May 2002
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Re: RA28 IRS
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Wed, 03 November 2004 02:20

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You guys might be interested in this then.
I have since the weekend and will be playing again this weekend pulled the diff out and have currently an RT142 IRS sitting roughly in its place. At this stage it was just to make sure it will fit, this weekend I will be removing the lower control arm mounts from the chassis and the front cross-member will mount to this area, rear section of tall-shaft from RT142 should (will know once control arm mounts are removed) bolt to front section of celica tail-shaft behind center bearing. Not sure about cross-member on top of diff until I can jack it high enough but it looks like it will line up with chassis rails. Still not 100% sure it will fit, but looks very, very promising .Will take photos and let you know this weekend.
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Location: Terrigal
Registered: May 2002
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Re: RA28 IRS
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Wed, 03 November 2004 02:41

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Very interesting im at terrigal so not too far from newcastle.. Maybe I could have a look one weekend??
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Location: Newcastle
Registered: May 2002
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Re: RA28 IRS
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Wed, 03 November 2004 13:35

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Joel PM sent.
Once I have some photos might have to get someone to host them so all can see.
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Location: Melbourne
Registered: May 2002
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Re: RA28 IRS
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Sun, 26 June 2005 11:35

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I was just looking at the spare MA70 IRS i have sitting here and my MA45
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Location: Adelaide
Registered: September 2003
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Re: RA28 IRS
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Sun, 26 June 2005 12:59

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ooooh interesting and what was your verdict allan
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Location: Melbourne
Registered: May 2002
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Re: RA28 IRS
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Sun, 26 June 2005 13:36
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barned01 wrote on Sun, 26 June 2005 22:59 | ooooh interesting and what was your verdict allan
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Ohhh fuck no way!!!
i have not had a look yet but the ma70 track is HUGE compared to the ma45 AFAIK ill get around to jacking it up for shits and giggles anyway...
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