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Casper0878

S13/S14 subframe vs T3

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Casper0878    0

I am rebuilding a 1978 280Z and was planning all along to pretty much buy all of the suspension items available from T3, minus perhaps the coilovers since I wanted to go with BG Racing. I want to do a 2JZ swap with maybe a Z32 transmission and want it to be a fun street car. I will not be doing any drag racing or drifting as I do not want to beat the crap out of the car after all the work I will be doing restoring it. Recently I met a gentleman who had the S13 subframe installed and who claimed I couldn't go wrong with either set up but that the S13 subframe would give me way more options for upgrades as well as flexibility and adjustability. He also claimed it would be cheaper, unless I had to pay a shop to do the labor, which I would since I do not know how to weld.

 

I contacted 2 companies that sell suspension items for the S30 and asked them their opinion on the pros/cons of the S13 subframe vs T3 stuff. This was their response:

1st company:

 

"As far as I know, there is no mount kit for putting a complete S13 subframe under the car.....for good reason. The S13 subframe is fairly complex, yet poor handling design.  The multi-link rear suspension is an inherently loose system. This is why they are such good drift cars, but rarely ever seen in road race. 

 
The Z car's original suspension geometry is a far better road race setup and linear handling design. It is proper sports car handling. 
 
The S13 subframe is a huge bulky setup as well. I think with a LOT of fab work you could put it under the Z car, but you'd be sitting at truck height because it would hang so low. 
 
In the end with all the fab work, I doubt you'd save much money, and you'd end up with a poor handling, ugly monstrosity of a mess under the car."
 
And the 2nd company:
 
"the s13 is a much better new technology it has similar to a double wish bone suspension which is far superior to the 240z rear suspension and differential. it will handle better. 
 
But it looks like a really long project with much welding cutting grinding fabricating. I would not do it unless i had all the tools already, and the skill to pull of such a project, and the amount of time for it. 
 
So do you have those resources is the questions?
 
If you decide to keep s30 parts everything will kinda bolt on. any upgrade you buy will bolt on. 
All the parts are the same price. brake kits, suspension parts. so i'm not sure which one would be cheaper to do. 
It's a hard questions."
 
Their opinions seems to vary, one saying it would handle well while the other saying it would handle better. Now I have not had the opportunity to drive a car that has either set up, but would like to know the opinion of the people who have done these upgrades. From the people with the T3 setup, how do you like it and would you go this route again? From the S13 setup, how difficult was the swap and do you wish you had gone with something easier and bolt on?
 
Any and all information, advice and suggestions will be greatly appreciated.
 
I did some searching around and found a few threads talking about the swap but not comparing the two in regards to handling and also cost.

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rturbo 930    27
Posted (edited)

I'd take the first response with a grain of salt, it seems he's got quite a bit of bias against the S13 suspension, and isn't aware that it has been swapped into an S30 quite a few times, and no, it does not sit at truck height.

 

I'm no suspension expert, but IMO the S13 suspension swaps are overrated, and generally make the car look a little goofy, because of the added track width. You would have to flare the car, no way around it. Visually, it doesn't fit, since the wheel mounting surface is close to the outside of the stock fender lip (give or take - wider than stock, that's for sure). If you were building a track car, it wouldn't matter, but it doesn't sound like you are. Another thing you have to consider is if you swap the rear suspension, and keep the front suspension, only one half of your suspension is upgraded, and the difference in track width is going to be very obvious with stock front suspension, visually.

 

The other thing is weight. I'm fairly certain that the S13 setup is quite a bit heavier than the S30 setup. Keep in mind, the S13 suspension includes the entire removable subframe, which the S30 doesn't have.

 

However, even if you were okay with those issues, I think the nail in the coffin here is your lack of ability to weld, fabricate, and engineer. Even if you could weld, you would still be short on skill, since that's only one piece of the puzzle.

 

As for handling improvements, I don't know, never driven either one unfortunately. But for a street car that you're not going to beat on, I'd say, 99%, not worth it, since you probably won't even make use of the benefits. Although you mentioned that you won't be doing drag racing or drifting, you didn't mention what you do intend to do with it. No mention of track or auto-x, is this strictly a street car? You may not even need the T3 setup. Speaking of, which parts are you referring to there? Just adjustable control arms, or the whole thing - control arms, struts, brakes, diff mounts, diff swap, etc? How much power are you planning on making? It sounds like the latter.

 

I think you should sit down and write out your specific goals for what you want the car to be, and figure out what parts you need to get you there. No sense in buying parts you don't need. I think some people who are new to older cars automatically assume that just because it's an original part it needs upgrading, which isn't really true.

 

By the way, how are you going to handle smog testing on a swap, since yours is a 78?

Edited by rturbo 930

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Casper0878    0

I'd take the first response with a grain of salt, it seems he's got quite a bit of bias against the S13 suspension, and isn't aware that it has been swapped into an S30 quite a few times, and no, it does not sit at truck height.

 

I'm no suspension expert, but IMO the S13 suspension swaps are overrated, and generally make the car look a little goofy, because of the added track width. You would have to flare the car, no way around it. Visually, it doesn't fit, since the wheel mounting surface is close to the outside of the stock fender lip (give or take - wider than stock, that's for sure). If you were building a track car, it wouldn't matter, but it doesn't sound like you are. Another thing you have to consider is if you swap the rear suspension, and keep the front suspension, only one half of your suspension is upgraded, and the difference in track width is going to be very obvious with stock front suspension, visually.

 

The other thing is weight. I'm fairly certain that the S13 setup is quite a bit heavier than the S30 setup. Keep in mind, the S13 suspension includes the entire removable subframe, which the S30 doesn't have.

 

However, even if you were okay with those issues, I think the nail in the coffin here is your lack of ability to weld, fabricate, and engineer. Even if you could weld, you would still be short on skill, since that's only one piece of the puzzle.

 

As for handling improvements, I don't know, never driven either one unfortunately. But for a street car that you're not going to beat on, I'd say, 99%, not worth it, since you probably won't even make use of the benefits. Although you mentioned that you won't be doing drag racing or drifting, you didn't mention what you do intend to do with it. No mention of track or auto-x, is this strictly a street car? You may not even need the T3 setup. Speaking of, which parts are you referring to there? Just adjustable control arms, or the whole thing - control arms, struts, brakes, diff mounts, diff swap, etc? How much power are you planning on making? It sounds like the latter.

 

I think you should sit down and write out your specific goals for what you want the car to be, and figure out what parts you need to get you there. No sense in buying parts you don't need. I think some people who are new to older cars automatically assume that just because it's an original part it needs upgrading, which isn't really true.

 

By the way, how are you going to handle smog testing on a swap, since yours is a 78?

Well I plan on keeping the 2JZ stock for now but eventually I want to do a single turbo, more aggressive cams, aftermarket ECU, bigger injectors and such. Going to go with 91 octane for fuel so no crazy boost. Would like to keep it around 450hp which should be easy to reach with the upgrades. Even stock I should be above 400hp I believe. 

 

I was going to get the front/rear LCA, tension rod, mustache bar, outer tie rod, drop mounts/dogbone combo, front and rear Wilwood brakes and I already have CV axles that need the adapter and the shorter shaft. Just wanted to refresh the suspension instead of just changing bushings and "cleaning up" the stock suspension. That was the plan and I had planned for it in my budget. I also have the wide ZG flares, just need to measure and cut to install them.

 

I might take it on the track at events but definitely not trying to win any. Just want to have fun and enjoy the ride. More likely I will be looking for fun canyon runs and cruising on the highway on weekends as I don't plan on making this my daily driver.

 

As far as smog, I know a shop in the area who helped me pass when my Integra couldn't. The mechanic across the street is a family friend so they hook me up. Just can't afford to get pulled over and sent to a referee for a visual inspection as the JDM 2JZ doesn't have an EGR valve.

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rturbo 930    27

Okay, your planned build is a lot less tame than I was thinking. Still, I'd stay with the stock suspension over the S13. At a minimum, I'd do a lot of research on the benefits and drawbacks of the S30 suspension vs the S13 suspension to see what you would actually get out of it. I don't think a complete suspension swap is something to be taken lightly. With that in mind, I'd get front and rear control arms and call it good. The control arms have the benefit of being adjustable, the mustache bar and drop mounts, not so much, at least not that I'm aware of. You already have an R200, so unless you're upgrading, I don't see the point. Up to you though.

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Casper0878    0

Yeah trying to find out as much information as possible before deciding what to do. I have time so in no rush to jump into anything. Just started following someone on IG who is going to do an S14 rear and S13 front swap so the pics and info should be very helpful. My stepdad and stepbrother both know how to weld, but it still feels like a very extensive undertaking. Will need to continue doing research but all opinions are welcome. Thanks for replying 

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This is in regards to the R200 short nose rear end conversion kit that T3 offers vs an S13 subframe swap?

 

What is your budget to do this?

 

A quality fabrication shop could suck up a lot of money quite quickly.

 

Funny I'd say I side a bit more with the first guy, the second guy being potentially more biased for the S13? Stock for stock I would say the S13 design is superior, but modified to modified, I'm not sure I could say the same.

 

An S13 subframe doesn't bolt in, in any way, shape, or form. It can't even be adapted without as the first person said a truck height as an end result (stacking the subframes). rturbo is correct that you can do it without the car sitting that high, if you do cut the factory frame out you can have it sit lower, but you have to cut the frame out, reinforce the cut area, add the different pickups, reinforce those areas, then you can bolt in the subframe. Alternatively you can just cut everything out and weld the subframe directly into the car and fill it in (most likely a poor example of this is what the first person was referring to). Most regular shops aren't going to be able to do this kind of work at least not well. This requires a chassis jig and welded braces to do absolutely correctly to prevent chassis warp.

 

It depends on your perspective. If you just cut everything out and make room for the subframe and just weld the subframe into the car, then it could be cheaper if you didn't really consider your time worth anything. However I can't see you coming out ahead if you did it the bolt in method. 

 

There are more options for brakes, rear diffs, arms, coilovers for the S13. However it really is a question of do you need that? The T3 conversion would let you use the rear diffs and would swap you out to wilwood brakes and remove the weakness of the half shafts and stub axles. So the difference then comes to which do you like more, the suspension geometry of the S30 vs the S13. In the S13 with the several arms you do get more adjustment and potentially most importantly the toe adjustments which you can't really do on the S30 with T3 equipment. Granted if this is a street car for the canyons you probably don't want to run a noticeable amount of toe to protect the tires and straight line stability which means that having that adjustment wouldn't help anyways. The comparison then lies in the inherent advantage and disadvantage of both setups. The multi-link setup is going to have 5 arms compared to the singular branched arm of the S30, however during cornering you can tune the multi-link to keep the wheel more or less flat due to the upper and lower arm design (takes more angle to pull them to a point of cambering). On the flip side you have to consider if you are running a lowered car on flares the ride height isn't going to change all that much and the spring rate will be higher so body roll will be less preventing the characteristics to really show for one over the other.

 

I can see where the first guy is coming from. To do it for less then the cost of the T3 swap most likely you are going to have a hard time finding a shop that really understands this swap. I would be afraid to see how they would go about doing 

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trackzpeed    5

Personally I would not do the swap on a 78..... Even if you have the "hook up" you are putting those shops in jeopardy of huge fines and pulled license. The suspension under the car is more than up to your use task with minimal upgrades.... I've been competing and winning in local AutoX events for years with only mild upgrades on 45 year old technology. I'm now running an LS1 swap and she is still doing great...... If your really want to toss out your money T3, AZC, Silvermine and others have everything you need for a bullet proof race set up...... And it all bolts on with minimal to no fab work. Just my .02. Good luck with your build and at least enjoy the process. Jim.

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Evlevo    0
Posted (edited)

I did this swap on a Z im restoring. Front and rear. This isnt a beginners project, but not as bad as i expected going into it. Anyone who says it will hang low or sit like a truck is talking out their ass. Mine sits basically flush with the bottom of the car, as it does in the s13/14. I thought about starting a thread to combined all the info i found and discuss the things i ran into but never got around to it.

 

**I would recommend this only if someone was doing the work on their own car**

 

The rear subframe took me about 8-10 hrs, over 5 days. not including running the brakes. I was on vacation and would go inside when i figured i had too many beers to be working under a car.

 

I would also recommend using a parts car. I bought a junk 240sx with some aftermarket goodies (coilovers) on it for 500 bucks. I stripped it of the parts i needed and sold the rest of the car for 400 bucks. 

Edited by Evlevo

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Casper0878    0

Wow, thank you all for your responses. Seems like the general consensus is do it if I can fab the work myself and forget about it if I can't lol. Hope to continue getting info on this.

Can anyone chime in on the differences they noticed? Did you go from stock S30 to S13/S14 and saw good improvements? Did anyone go from some T3 stuff to S13/S14?

 

Thanks again for the info!

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TUME    10

Sure, here is my build topic. http://forums.hybridz.org/topic/120418-arttu%C2%B4s-240z-never-ready/ 

 

There are few pics, but i have more and can always go downstairs to my carage :P

 

It´s R32 subframe but basically same as S13. Little bit modded, though. After i was struggeled this subframe to car, i got an idea of making subframe by myself. Well, maybe that day will come someday.

 

I agreed, if you can do fab work by youself, why not. If you have to do swap in a shop, hefty wallet is needed. It´s not so simple as weld in. Also keep in mind, that track width is increasing, you should do something to front also.

 

I have bit wider track in rear, but i have also rear bias weight ratio. Front heavy car with wider rear track is disaster.

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rturbo 930    27

I just watched those videos. WOW! That is a lot of work!!

Yep. Now thing about how much you're going to gain, and how likely to are to actually make use of it, especially on the street.

 

I'm a bit biased towards the stock suspension - IMO the suspension has a lot to do with what makes the Z what it is (and that applies to any other car too) - but the stock style suspension is really not that bad, and I really don't think a suspension swap is worth it. Your call though.

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TUME    10

I just watched those videos. WOW! That is a lot of work!!

It sure is, and, if you look at my pics and those videos you'll notice that i cut floor off much more. IMO those swedish guys ruined suspension geometry by mounting subframe too low. It will work but it's far where it has been origi ally designed.

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KAZU    13

It sure is, and, if you look at my pics and those videos you'll notice that i cut floor off much more. IMO those swedish guys ruined suspension geometry by mounting subframe too low. It will work but it's far where it has been origi ally designed.

 

I agree with you 100%. You placed the subframe appropriately.

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260DET    25

TechnoToy and Arizona Z both make great rear end stock improved setups, both specialise in race orientated parts for older cars. Either would be a far better option than messing around with a S chassis rear end, they bolt in simple as. As a foreigner it makes me wonder how come these specialist American suppliers probably sell more to people like me than Murricans, they never get mentioned on this forum.

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260DET    25
Posted (edited)

To elaborate, you won't be able to get the S chassis subframe high enough without extensive and expensive body modifications. Of course it can be bolted in easy as but what about being able to use the new suspension at it's correct OE alignments? Unless you want a high arsed car the suspension will have to be lowered way past it's preferred alignments which means the performance advantage of the S chassis is lost.

 

The lesson is, if you are serious, improve what you already have.

Edited by 260DET

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jthom5147    1

Attached are some drawings of the s30 undercarriage and 240sx subframe hard points overlaid at 240sx factory ride height and my Z's current ride height with axle position overlapping as reference. My brother did most of the drawings for an iterative project feasibility study I hired him for.

 

You can tell the front RLCA mount is directly in the S30 frame and the upper traction rod is deep within the z tool compartments.

post-20551-0-42975700-1492210903_thumb.jpg

post-20551-0-56736300-1492211001_thumb.jpg

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TUME    10

Those drawings seems to be right. Here is pic how much it takes to modify chassis to take S13 subframe. I had to modify little bit of those frame rails, also, to make room for control arm attachments.

 

It´s pretty easy to found right height. Just mount rear mounts to level with rear frame rails and keep upper arm (camber and traction) attachment points to level.

post-3341-0-59569200-1492251131_thumb.jpg

post-3341-0-07852800-1492251152_thumb.jpg

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jthom5147    1

We're looking into significantly narrowing the track to bring the s13 hubs closer to the Z hubs and see where the mounts fall inside the body.

 

the OE subframe would get ditched and replace for a two-piece weld in rear tube frame integrating the mount points. The main lower hoop would be welded in first to reinforce the chassis, cutting out the tool compartments, and then welding the upper hoop. Finish with sheet metal repair and a full cage which will tie the chassis, cage, and new subframe together.

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