R31 Coilover Suspension.

[prescott06]

Hi guys,

I've been doing some research into the coilover conversion for the R31 (a wagon in my case). I realize there is a perfectly good /easy way of doing it. I.e buying S13 coilovers, hubs, LCA's and brakes. But this seems to be quite an expensive way of doing things (although probably with the least amount of custom fabrication), especially concerning brake options (I understand R33 GTS-T calipers fit, but the rotors have to be redrilled to 4 stud) as I think calipers alone go for around $300?? with rotors (blanks to be re-drilled) and pads on top. Also geometry changes seem to be an issue, the S13 LCA's being longer, and therefore resulting in a lot of -‘ve camber? (correct me if im wrong). This can be sorted out through the use of camber tops (adding more $$ to the shopping list).

In order to avoid using the S13 gear I was thinking about other ways off connecting coilovers to the r31 hub assembly. Having seen MacPherson struts on my N14 Pulsar I understand the strut/spring assembly bolts to a bracket on the hub. (Shown in the 3D colour pic)

I thought it would be possible to attach coilovers to the R31 setup in a similar way. I'd remove the spring and shock insert from the strut tube and cut the strut tube down, leaving enough length to weld a bracket on which would accept the bracket (possibly cut from 16-20mm thick steel bar) on the bottom of the coilovers. (see dodgy drawing)

The only problem I can see with this design is it might introduce +'ve camber as the coilover body will be pointing slightly into to car to account for the mounting point (bracket) being offset, i.e the base of coilover would be, say 50mm (depending on the width of the bracket), further towards the body of the car. However, by rotating the bracket 90 degrees so it points forward (i.e the mount point and coilover body would sit infront of the original strut) positive caster would be introduced! Although ultimately it may prove too much of a geometry change wherever the bracket was welded on...

After a little searching (as in the first google search for "S13 coilovers") I found this:

http://www.redz31.com/pages/coilovers.html

Z31 guys obviously faced the same problem, i.e no off the shelf coilovers readily available. Basically (if you can't be bothered to read the link) he cut the struts (similar to my idea) and slotted the bottom of the coilover body inside. Then he welded the strut to the base of the bracket on the coilover. (If you don't get what I mean, and you probably don't, follow the link). The only problem with this is that he had to flare the tube out slightly and add a bit on from (futher up the strut) to accommodate the bottom of the coilover. This could be made easier by removing the strut tube at the base and welding on a new piece of tube which is the correct diameter, therefore having only 2 welds instead of 3. The other thing that concerns me is the possibility of damaging the internals of the shock when welding, which is why this guy welded to the bracket, so it *should* be ok.

Well, that's where I've got to with my research. The idea has only been in my head for a couple of days, so I am by no means saying that this is defiantly the way forward. The full S13 conversion is still looking like a very good idea, but, for me, the custom way would be a lot cheaper as I have access to 2 different engineering/fabrication workshops through my family and my GF’s (also where I’ll be working as of next week)… Although my "custom way" doesn't do anything with brakes etc, so I'd probably look into making up some brackets similar to those already made up by Prestagea (r31 forum) and get some decent callipers. But I can do that later down the track.

Any comment or opinions (the more technical the better) are very welcome

(BTW, this I also posted this on r31skylineclub.com about 30mins ago)

Cheers.

P.s If this is in the wrong section, apologies, and feel free to move...

Edited June 7, 2007 by prescott06

[NismoR31Jet]

Fitting coilovers are no drama to an R31.

To fit the Teins into my wifes R31 we used the S13 knuckles and coilover assembly on the R31 LCA. The R31 lower ball joint is a perfect fit for the S13 knuckle, this way the wheel does not hit the wheel arch as it would with the S13 LCA.

Modding the R31 strut is a nother way of doing a coilover, but the cost of decent shock inserts alone is more than a set of good second hand S13 coilovers, and by decent, I mean adjustable Koni or Bilstiens.

Aussie R31 struts are useless for decent brakes as nothing is a direct fit and proper hubs to mount R32 onwards disks are almost impossible to find these days and cutting up a stock disk is not a real good way of making a hub.

The availability of brake options are endless for the S13 knuckle, and using as many standard parts as possible means replacements are easy to find if you break something.

[prescott06]

Fitting coilovers are no drama to an R31.

To fit the Teins into my wifes R31 we used the S13 knuckles and coilover assembly on the R31 LCA. The R31 lower ball joint is a perfect fit for the S13 knuckle, this way the wheel does not hit the wheel arch as it would with the S13 LCA.

Modding the R31 strut is a nother way of doing a coilover, but the cost of decent shock inserts alone is more than a set of good second hand S13 coilovers, and by decent, I mean adjustable Koni or Bilstiens.

Aussie R31 struts are useless for decent brakes as nothing is a direct fit and proper hubs to mount R32 onwards disks are almost impossible to find these days and cutting up a stock disk is not a real good way of making a hub.

The availability of brake options are endless for the S13 knuckle, and using as many standard parts as possible means replacements are easy to find if you break something.

I never realised the the r31 LCA and ball joint was compatible with S13 knuckels (by knuckels i assume you mean the hub assembly - including the brackets for callipers etc).

That all but removes the issues with the change in geometry associated with the S13 LCA's.

What about tie rod ends? Did you use spacers or get them lengthened (i would probably lengethen mine) or just stick with the 5-6 threads?

Cheers.

[skybt1]

id go with the s13 conversion. jump on the silvia forums and see if you can source some hubs and stub axles for

the front, and you'll be set! But then you will have to change your whole front brake set up too.

I used all s13 parts on the front, its all pretty much interchangerbale. Except for the tie rod ends.

I dont know what they are like on the r31 but i know on the r30 some machining has to be done. But they are probably

the same, nissan dont change much when they are on a good thing.

I dont know if you have read this already http://www.skylinesaustralia.com/forums/in...showtopic=75610

but its probably 99% the same.

Edited June 7, 2007 by skybt1

[prescott06]

id go with the s13 conversion. jump on the silvia forums and see if you can source some hubs and stub axles for

the front, and you'll be set! But then you will have to change your whole front brake set up too.

I used all s13 parts on the front, its all pretty much interchangerbale. Except for the tie rod ends.

I dont know what they are like on the r31 but i know on the r30 some machining has to be done. But they are probably

the same, nissan dont change much when they are on a good thing.

I dont know if you have read this already http://www.skylinesaustralia.com/forums/in...showtopic=75610

but its probably 99% the same.

Yeh, knowing that the S13 hubs and R31 LCA's/ball joints are compatible changes things a lot. I'll keep my eye out for S13 hubs, stub axels, rotors and callipers.

Is there anything else im likely to need (apart from coilovers )?

[skybt1]

nope. easy as!

[NismoR31Jet]

As for tierod ends, I stupidly straightned out the R31 tie rod ends and used Nylock nuts for a few drift events but have a heap of play now in the tie rod end. I have a pair of S13 tie rod ends and I am getting some spacers made up as in the photo attatched that I stole from the R31 forums.

Alternatively, if your car runs the Jap rack (the rack that is not a TRW rack), S13 tie rods and rod end assemblys will go straight into the R31 rack meaning no dramas at all. I think Early series 1 had the jap rack.