Early celica IRS conversion

[tricky]

With regards to other models, don't some of the RA65s have IRS? Would they be suitable?[/URL]

Yes, it's been done by a dude with a 3TGTE RA40... Well he used a corona/cressida mix of parts, but the basic design is the same... Fab wise, this is the easiest option, but compared to more modern designs, the 1980's toyota gear is arse. *A70 and JZA80 supra stuff is seriously heavy, and the track is significantly wider, so for most this wouldn't be an option. I'd love to have a look at IS200 gear, because they handle so well from the factory. The CCA mount flex is an easy fix- Just remake the mount with thicker steel.

The more I look at FC stuff, the better it looks too! I haven't checked parts availability though. Other options involve going nuts with the grinder and swapping floor pans with the donor vehicle... Of course, this is the point of no return!!

[ViPeR_NiPPleX]

RA65/MA61/MX73/MZ10/etc has semi-trailing arms. Simple stuff really, just not great for adjustability.

For the ultimate IRS setup, you could contruct a custom cradle with rose joints and run double wishbone. Probably not practical or cost effective in a 70's celica however.

[TurboRA28]

The track width seems one of the biggest problems..

I've helped a mate with an IRS conversion into a live axle car. Lots of work but the results are awesome. We used a Nissan 280zx setup as width wise it was the narrowest one we could find. But its semi trailing arm.. Nicer to have a double wishbone style.

[timbosaurus]

The track width seems one of the biggest problems..

I've helped a mate with an IRS conversion into a live axle car. Lots of work but the results are awesome. We used a Nissan 280zx setup as width wise it was the narrowest one we could find. But its semi trailing arm.. Nicer to have a double wishbone style.

The track of the silvia is quoted as 1360mm on the rear - this the same as the RA28. What I don't know, though, is what constitutes "track" in each of these figures. I'm pretty sure it would be hub-face to hub-face in both situations.... but I would want to confirm this.

Joel, you posted a reply in the old forums saying you saw a '28 with s13 diff and disc brakes.

http://forums.toymods.org.au/index.p...eaffcb541f13f4

Do you remember whether this was the whole cradle? Any idea who's car that was now that ur older and wiser?

[Turdinator]

The track of the silvia is quoted as 1360mm on the rear - this the same as the RA28. What I don't know, though, is what constitutes "track" in each of these figures. I'm pretty sure it would be hub-face to hub-face in both situations.... but I would want to confirm this.

I believe track is measured from center of tyre to center of tyre

[tricky]

For the ultimate IRS setup, you could contruct a custom cradle with rose joints and run double wishbone. Probably not practical or cost effective in a 70's celica however.

It's been done for AE86's by a japanese company (but then again, what hasn't?), and if there was enough demand for one in an old school celica, it would be a path worth considering, but bank on a group buy resulting in an undressed $2000 cradle... Also one to investigate when I have the time

EDIT: I just did a bit more looking on the FC RX7. I has "dynamic tracking suspension", which is a toe/camber self adjustability based on cornering speed. It seems it isn't as flash as I thought... Essentially a jazzed up semi trailing arm setup. See pic below.

[WDE_BDY]

I believe track is measured from center of tyre to center of tyre

Yep, so the Silvia is likely to be wider due to FWD offset wheels. Difference is likely to be within 15-20mm per side though and could easily be addressed with the right offset wheels, assuming you are doing a front upgrade as well it shouldn't be a major to keep similar offset front and rear.

Callum

[TurboRA28]

Hmm why is my memory telling me S13 was closer to 1460 track... oh well!

[WDE_BDY]

With 40P wheels the Silvia would be 1440 hub face to hub face, assuming 1360 is correct. I could be wrong but I though the TA22 had a 1370 wide diff, so track around 1320 assuming 25P wheels. Has anyone got accurate measurements for either and exactly where they measured from?

Callum

[RAd28]

just throwin some ideas into the pot... what about IRS from 240/260/280Z? or MA61?

i know the tech might not be up to date with todays standard, but if it's cheaper/easier then S13/14 etc, then it might be suitable...

[WDE_BDY]

The *A6* is what I used for my Starlet, but cost wise to fit into a Celica you are probably better to just play with the live axle rear rather than semi trailing arm. I had a lot less restrictions for my car on looking pretty, retaining a back seat or fuel tank etc as its a race car but I wouldn't do the same swap for a road car.

Callum

[TurboRA28]

280zx is a very good width for old skinny cars. Simple mounting points also.. 2x at the front and 1 in the centre at the rear.

But if going to all the trouble of IRS swap would it be better to try for something that isn't the semi-trailing arm design?

[RAd28]

lol... i wouldn't know what IRS setup the old datto's had... never had a good look at one, as i said just throwing ideas into the pot...

so the 280ZX irs is similar to the VR commodore IRS? ie more like independent trailing arm?

[timbosaurus]

Ah... that would make sense.

Was wondering why everyone was saying the Silvia has a wider driveline when the track seemed the same. I already have Silvia wheels on my car so I should've known! At least finding wheels wouldn't be a major concern lol.

If someone saves me the leg work in finding the measurements from hub-to-hub on a s13 sitting pretty, They'd well deserve the rep

Regards to cost, I don't think much would be cheaper than an s13 cradle. They seem to come up for around $3-400 including diff, discs, driveshafts etc. that's hell cheaper than a hilux upgrade with discs! prolly even cheaper than finding a MKII diff and doing the disc brake conversion! The diffs seem to be pretty strong, but i'm not sure whether they are "low-torque-revvy-SR20DET" strong... or "twin-turbo-boosted-1UZ" strong


And when I go IRS, I don't really want semi-trailing arm. Nothing wrong with it back in the day... but not much right with it these days Going to do a job, may as well do it properly.

*awaits hub to hub width of s13 rear driveline.*

Timbo

[timbosaurus]

yeah, old Dattos, Commos, and even old Triumphs used semi trailing arms. Good for the time (commodore excepted ) but out of date now.

Double wishbone is where its at. Well... Lexus's take on IRS is where it's at, but I can't afford that just at the moment