Just about to start work on fabricating the adjustable rear end for my 180B. I was planning on moving the mounting points for the trailing arms as far outwards as possible on the rear x-member to match the widened 200B front end and get the wheels / tyres filling the rather large 180B rear guards. I'm looking at a maximum of maybe 30mm wider each side.

This will effectively move the lower spring mount on the trailing arm out by the same amount, but the upper spring mount on the body will stay in the same place. My concern is that the spring will then be a bit crooked, possibly fouling on the "column" bit of the body that the spring fits over ?

Anyone done something like this before ? If so, any issues or am I worrying about nothing ?

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1970 ex Group A Rally P510
1971 P510
1972 180B SSS
1965 SP310 Fairlady
1966 SP311 Fairlady

Dave, Perfect excuse to run MR30 rear arms and convert to coil overs in the back

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1928 Model A CC Pickup

'filling up the guards' is not really a perfect reason to justify all the mods it will need to work properly.
How about wider rear rims, rims with different offset or just wider tyres?

I've recently noticed that 200B IRS arms are very simillar to the MR30 and OEM 1600/180B arms, they would seem like a straight bolt up conversion then all you would have to do is come up with a shock/spring coilover arrangement and re-inforce the top shock mount on the chassy.

moving it 30mm would definately move the spring seat off, I think this idea would work if you were thinking of moving 5-10mm.

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"You stay classy OzDat"

Yep, that's only a distant secondary consideration.

The main reason is that I've added close to 50mm extra track to each side at the front, and I was thinking I'd widen the rear track to match.

The work will be done anyway (to achieve adjustability in the rear end), its simply a matter of welding the trailing arm mounts further out on the x-member.

Different offset wheels would do the trick I guess, but I already have a set (and also want to be able to swap the wheels and tyres with my 1600 whenever I use the 180B on the track).

Coilovers - hmm, that's a thought.

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1970 ex Group A Rally P510
1971 P510
1972 180B SSS
1965 SP310 Fairlady
1966 SP311 Fairlady

another thing to consider is the toe angle change when bringing them further out, the x-members have that straight section where the diff goes through the middle then the swept angle forwards to where the arms bolt up to and where it mounts onto the chassy.

just another thought.

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"You stay classy OzDat"

The 240K rear arms are meant to be the go. I've not measured them myself, but 20mm wider track (per side ?) and they've got the larger outer bearing and thus can take a little more punishment.

You'll find that the furthermost outboard mounting tab occurs just before the crossmember necks down for the end bush holder as well. There might be enough room to move the arms outwards a little bit, but I would have thought 30 odd a side would be out of reach.
Toe change won't be affected. The angle of the crossmember sets this, not how far apart the arms are. I have heard of people changing the angle and getting correspondingly better tyre wear from the mod. But the closer you come to a full trailing arm, the closer you get to needing another set of links to restrain the wheel movement as well. I'm not brave enough for that kinda thing.

Would have thought having the spring at an angle would be a bad thing. Introduces another force vector into the equation and may result in one side of the coil binding before the other. I'd imagine it wouldn't do a lot for the linearity of your spring rate either.

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Happiness is watching the race.... in your rearview mirror

Oh yes very true because the angle is the same but just the position of the arms change, in that case Dave why not opt for the easier alternative and move them out by say a safer range of 10-15mm and some bolt on spacers or if willing which I know you're not replacing them wheels with something else that would work on both cars?? otherwise stick to the original plan and convert the rear to coilovers, I've looked into this and you would have to pretty much come up with a shock (Koni or the like) that can have a spring seat/perch attached to it's body (no welding) so that you can slide a threaded collar onto it just like the T3 GC setup for the front ends; would have to work out spring rates and legnths and come up with a top hat.

attached is a close example of what I'm talking about and also the T3 setup which is not the best but just to give you an idea.

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"You stay classy OzDat"

Dave have a chat to Leigh (Lag510) he has done the Mr30 arms and coilover setup on his 1600.

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1928 Model A CC Pickup

what axles will you use?

I'll be running CV axles (hopefully of my own making), and was hoping that widening the rear track would maybe open up a few more options from donor cars with a wider track than the 180B. Some of the ones I've been looking at are early BMW's (318i, from memory) which run a similar style of CV joint to the porsche / VW ones that Wolf Creek use in their CV axle conversion. Spent a few hours at the wreckers a while back with tape measure, but have managed to lose the bit of paper with all the measurements

It may become a non-issue - was having a close look tonight and as boyracer points out - there is a "narrowing" on the rear x-member that may prevent me going too wide. I might have to hack the existing brackets off and see what clearance problems I will have there.

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1970 ex Group A Rally P510
1971 P510
1972 180B SSS
1965 SP310 Fairlady
1966 SP311 Fairlady

you'd almost be able to fit std mr30/280zx cv axles and companion flanges if its the right width?
Or what about using the whole rear end crossmember and all? Most of the skyline rear ends have adjustment for toe etc standard.
A while back someone on here did this using a whole dr30 rear end in theyre irs 200Bcoupe...

before any welding or custom making of cv's with a hacksaw and file, def look into the possibility of using a stock setup like the mr30 cv setup inc arms

while the shell is just a shell, now would be the time to strengthen the shock tops so they can take the load a coilover setup will produce if you go down that route

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http://www.healingchambers.com.au

I have the 240K conversion under my 1600 rally car for all the fore mention reasons, does require cutting the 1600 shock mount and fabing onto the 240k arm. Parting out this car next year if interested

i still don't understand why ppl are more inclined to the MR30 arms when the 200B IRS ones look identical to the original 1600/180B arms????

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"You stay classy OzDat"