3t-RA40 with IRS * New Pics Added*

[3t-RA40]

This was in the old forums so I thought I might bring it back.

OK here's a basic description of what and how i did the conversion. Purchased Corona RT142 IRS, dropped out existing diff (obviously), IRS came with back half of tail shaft which just happened to bolt up to front half of my Celica tail-shaft. Tried jacking complete IRS into position but realized that lower control arm mounts on car were in the way so I removed them. Once again tried but still needed another 15-20mm so IRS mounted up past sill height so cut out where the lower control arm mounts used to be as pictured and will box out this section.


Once again tried to jack into position but now fouled the chaise rail by about 5mm. Rather than cutting into the chaise rails decided to modify the IRS front/main cross member by cutting sections out and boxing back in as pictured.


With this done it full filled the height issue. Next cut away pan hard bar mount as no longer required and added in two pieces of flat plate where the pan hard bar chaise rail joined the two main chaise rails then added two box sections to mount the diff cross member to as pictured and also some angle as pictured in second photo below which holds main cross member in place.


Next was the springs. At the moment it has cut celica springs in it which don't fit properly as the RT142 spring is a larger dia than RA40 so I'm having some custom ones made at the moment. But even with them as low as they are it still rides really nice but have some real issues with camber and ground clearance. New springs will be around 25-30mm taller.

These are the new springs added, camber is not to bad and like I said we might try and correct this with off set bushes in the trailing arms.



A couple of things to point out,
1 - Using Cressida MX73 4.1 ratio diff, ventilated disc's and calipers over Corona RT142 3.7 ratio, solid disc's.
2 - Diff cross member is Cressida MX73.
3 - Corona RT142 wheel track 1350mm, RA40 1350mm
4 - Using Corona RT142 main cross member as Cressida MX73, although it uses same mounting position, its track is wider (but may be OK?).
5 - Corona RT142 complete IRS (minus one caliper) cost $300 from local wrecker and the Cressida MX73 cost $350 from a different local wrecker. All other modifications were made by myself so only my time and the cost of some brake lines and new springs.

I will take some photos tonight with the new springs in it and also over the next few weeks as I finally pull it out and tidy it up.
Cheers,
Neil.

[oldcorollas]

thats awesome
great to see someone who just went "bugger it, it's gonna fit somewhow" and just made it work!
you make it look so easy too

hmm.. engineered/able?

[gianttomato]

Great work!

[ViPeR_NiPPleX]

i like it! hmm... i have an sa63 rear end, and im sure i could pick up an ra40 for free.. one day

[brett_celicacoupe]

did you ever get to a stage where you thought, what happens if it wont work at all, after youve cut parts out of the chassis.

thats what im scared of with mine, doing nearly irreversible modifications.


very nice work on this. i hope to try it for myself oneday

[3t-RA40]

did you ever get to a stage where you thought, what happens if it wont work at all, after youve cut parts out of the chassis.

thats what im scared of with mine, doing nearly irreversible modifications.


very nice work on this. i hope to try it for myself oneday

Yes and no, spent a lot of time researching and then when I got my hands on the IRS spent even more time checking things before I started cutting anything. Even once I started the cutting process I only did it in stages until I got it right (in my opinion anyway), I think from memory I had the assembly in on out about four times. Concept to on the road was 6 months.

[thechuckster]

great to see an RA40 modifed with such enthusiasm ;-)

queries: How are you fixing the camber? (kinda looks like Norbies white nightmare from behind) and any issues with mounting and obtaining suitable shocks?

[3t-RA40]

great to see an RA40 modifed with such enthusiasm ;-)

queries: How are you fixing the camber? (kinda looks like Norbies white nightmare from behind) and any issues with mounting and obtaining suitable shocks?

Camber's not so bad now that I've got the new springs in (which I was going to take a photo of last night and didn't will do tonight). Rather than getting carried away just yet with adjustable camber pins in the back, we were contemplating using offset bushes in the trailing arms. You know one up, one down on each side to try and correct. Will start with one on the outside first and if this is not enough then do the inside.
In regards to shocks just used some new KYBs to suit RA40. The mount at the bottom on trailing arm is not the best but it works (will take a photo tonight), this is one of the things I'm thinking of changing in the next coulpe of weeks, nothing major just gettin the angle right.

[brett_celicacoupe]

does it tramp like a bitch?

i take it that its a MX73 cressida you arer referring too in your origional post?

[3t-RA40]

does it tramp like a bitch?

i take it that its a MX73 cressida you arer referring too in your origional post?

It did tramp with old springs/shocks but not with the new ones.
Yes it's MX73 and I will edit it now to show this, thanks for pointing that out man.
Cheers,
Neil.

[1JZ.747]

thats great work neilo.

have you had a chance to do some spirited driving to test the handling differnece?

you just had to put something cressida in it didn you

shane

[3t-RA40]

Sorry double post

[3t-RA40]

thats great work neilo.

have you had a chance to do some spirited driving to test the handling differnece?

you just had to put something cressida in it didn you

shane

Handles much the same, bit smoother though. Really needs a sway bar on the ass end not that .
Mainly wanted IRS because they said it was to difficult and the 7.5inch diff centre so as not to worry about breaking diffs with the Hatech now going on .
It's just that whole cressida thing you guys crap on about, so I though I would see what all the fuss was about . Maybe I should buy your turbo then I'll really be coping , have you sold that thing yet?
Luv,
Neil

[1JZ.747]

nope. still have it. still for sale.

i wanted the t51 on it this saturday, but its not going to happen. hopefully i can sell this one by may and put it on for compak attak.

every one appears to be worried about lag. full boost at 4200 and boost from 2700 its not that laggy.

[3t-RA40]

My little turbo dosen't really build or make boost any faster than that, but I don't think your turbo on my car would be that responsive? To small engine capicity?