the (ae86) weight reduction thread

[slydar]

im about to start a build on a hatch back (ae86).

i would like to hit the the low 800s with a fairly "normal" initial set up/build.

plans so far are -

normal 16v 4age

t50

t series rear axle

JDM doors gutted with NO windows.

3mm polycarbonate side windows.

no trim, seals, window moulds etc.

3/5mm polycarbonate rear hatch window.

JAZ (brand) poly seats

no dash

no cage

14x6.5/7" volk 3pc wheels

FRP bonnet

small dry cell battery

scratch built loom

and a few other little ideas ive been thinking about for a while.

initially i want the car to look fairly normal from the outside, something you could almost get away with on the street.

i plan to use the car for a variety of motor sport. initially drifting as it is the most accessible/familiar to me. but also sprints and hill climbs. with maybe a view to it evolving into more of a sports sedan later on (which wouldnt really preclude it from participating in any of those disciplines later).

ive had a dig around our forum and others but havent come up with a lot of hard numbers re whats realistically achievable.

i am intersted in people posting links to build/tech threads with info on what people have done and actual measured results, or weights of their own cars and a quick run down of specs/mods.

the purpose of this thread is to get a realistic idea of what sort of numbers are actually achieveable.

[McLEVIN]

well i would say you will need to replace all panels, hatch and bonnet with frp/carbon...i would assume you've seen mcnsports ae86 thats supposedly one of the lightest 86s around

[slydar]

ive seen threads discussing that car and its weight on driftworks, from what i remember towards the end of the thread, with its current set up, with the rotor and cage darren actually claims well under 800kg. im not sure i beleive that personally. but to be honest that gives me optimism.

for stage one, i plan NO cage and normal driveline so i would have to be a good 50kg ahead of him there.

[willa]

Also exhaust is a big place to have a win. No muffler is the easiest and cheapest way, or where mufflers are needed keep them short and sweet.



...titanium ftw ;)

[AIROCOBRA]

Here is some inspiration for you all --- here are a few forced weight reduction mods on my Khanacross 86.

http://www.ae86drivingclub.com.au/dcimages/2/2/8/8/276568.jpg

http://www.ae86drivingclub.com.au/dcimages/2/2/8/8/276569.jpg

[xero]

have a look at the hot version N2 video's and see what extremes they go to and they weights they are achieving.
from memory they range from 790kg up to 900kg for some of them

[ehendrikd]

Standard empty ADM AE86 fuel tank is approx. 13kg whereas an empty 45 litre polyurethane fuel cell is approx. 5kg.
Pitch sound deadener in an ADM AE86 is approx. 20kg.

[johl]

d-mac makes a fibreglass roof replacement i believe. that will be a good c.o.g saving item. if you were to run fibreglass rear over fenders you can get rid of almost all the metal behind the rear strut mounts. as you said it would look normal from the outside but it would just remain a skeleton inside.

similar to this but retaining the where the tail lights and shit go
http://www.ae86drivingclub.com.au/dcimages/7/3/60128.jpg

[Delazy]

CSO Japan make a carbon roof skin... *dreams*

[s13 james]

in the pic above of white 86,what is he going to do with the rear end?

[johl]

its the need for speed rotary 86 from d-mac. he put a one-piece fibreglass panel there. no lights just a panel

[hachi_dk]

fibreglass roof and no cage sounds like a death trap.

[turn69up]

True story^^^ :rolleyes:

[McLEVIN]

Tbh I think once you start cutting out all the metal you're messing with structual integrity of the car. And replacing doors panels with frp/carbon ain't gonna do much in protecting you if crash/roll it. Depending on how extreme you go a cage doesnt sound that bad of an idea

[timbo]

I think the easiest way is to ditch all the glass for lexan. Fibreglass hatch doesn't weigh much, if any, less than the standard metal one. Fibreglass bonnet would be the only worthwhile panel to replace; guards are already light and the roof skin is so thin I can't see how the effort of a fibreglass one is worth the while.

Also depends on how much you want to cut up a shell whilst leaving enough behind to hold it together without a cage.

[Sam-Q]

A cage might make the car faster overall.

Stock alternator brackets can be surprisingly heavy.

Once you change the doors and hatch+glass on our type of cars the weight flies off. Stupidly heavy doors

[jakel]

Got told when I asked a mate at work who has built many v8 commodore race cars about getting lexan to replace the glass and he said just make an extra 20 hp, haha.
I want to try and get my T18 down to about 900kg I would be happy with that but anything under 1T i would be happy with.

[slydar]

ive done a fuel cell set up before. i will probably go down that road again but maybe not for stage one. done sorta similar to whats suggested with the rear 1/4s too. but because as stated i dont want to run a cage to begin with, i think i'd like to leave most of the uni body in tact.

[AJPS]

take out half the bolts in the guards etc and hole cut along the sides of the hatch and other non strutuaral pieces

[jakel]

Go crazy with a hole saw haha.

[Cerby86]

Go on a diet!

[Delazy]

http://img311.auctions.yahoo.co.jp/users/3/3/4/6/kurumabaka888-img600x450-1219569653e2n13q87609.jpg

http://img281.auctions.yahoo.co.jp/users/3/3/4/6/kurumabaka888-img600x450-1219570292hxzztm46890.jpg

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[Rice86]

http://img311.auctions.yahoo.co.jp/users/3/3/4/6/kurumabaka888-img600x450-1219569653e2n13q87609.jpg


^^^ Thats not doing it right

the awkward moment when doing it right the first time is not possible for the average hachiroku owner

http://www.ae86drivingclub.com.au/dcimages/1/0/3/1/276642.jpg (http://imageshack.us/photo/my-images/824/ay0f0250.jpg/)
http://www.ae86drivingclub.com.au/dcimages/1/0/3/1/276643.jpg (http://imageshack.us/photo/my-images/209/img0129mw.jpg/)

so the rule is simple: go full carbon, the hard part is going full carbon..so simple yet so hard

[Rice86]

on another note

my coupe i bought was claimed to be at 970kg? without driver
it had fiber glass vented bonnet and pair of front guards, no rear seats, 50% sound dening removed, not sure if it was 100% as not bothered to check under the front half of the carpet, no air con as per standard...had power steering setup and 90% of plastic interior, bucket seat for driver and normal for passenger..

for a car claiming to be 970kg, it sure did felt lighter then when i drove a hatchback with very similar weight deduction without power steering on the hatchback too..maybe its just a coupe thing =p

P.S Notch backs are more rigid then hatchbacks, can speak from experience now
just sayin.

[Sam-Q]

I am very unsure about the carbon roof thing, I just don't think there's lots of weight in it and it's a strong structual component of the car

[Delazy]

I am very unsure about the carbon roof thing, I just don't think there's lots of weight in it and it's a strong structual component of the car

Strangely I agree, but a lot of evo's run carbon roofs and drop reasonable weight..

If I was to ever do it, it'd purely we wank factor..

[Sam-Q]

well I guess it is the single best place to loose the weight.

Also anyone who has an electric sun-roof should take note- they are 20kg!!

[johl]

i would only go carbon roof if i had a reputable cage and it had gussets on the a and b pillars

[timbo]

This is what I would do:

Remove all trim
Remove door cards
Top of dash only
Remove heater or air con stuff
Remove sound deadener
Remove glass and replace with lexan
Remove bonnet and replace with fibreglass/carbon fibre
Remove fuel tank and replace wheel well, add small fuel cell
Remove radiator wall and replace with simpler, lighter design

[ehendrikd]

Remove radiator wall and replace with simpler, lighter design

Here was my solution:

http://img406.imageshack.us/img406/9783/photorz.jpg

Square and angle alloy. I found that only the two bolts on the inside of the headlight enclosures were needed to support the headlights and grill.

[lappy]

Cut up the steering column and all the shit around it save maybe 10-15kg:
http://www.ae86drivingclub.com.au/dcimages/5/3/7/71882.jpg

Sorry best pic i have of it. Then cut off all the random brackets that attach to the firewall (also seen in pic)

Also what i have done with mine aswell as remove sound deadner is scrape all the seam sealer off, like where the floor joins the sill panel(sides) and the interior side of the front wheel well, theres heaps of it on all the seams in the boot. If yout going extreme get the underneath of the car sandblasted so all of the undeside sound deadner is removed (The ruff shit in the wheel arches and such). Buy lighter rims and so on.

But its also about weight distro aswell. Put your fuel cell directly over your diff if you can, rather than against the rear panel. Put the battery inside/rearward of the car rather than the front, cut the original battery mount off. Anything or bracket/ mount you are not using remove it or move it rearward.

[Sam-Q]

that's a very good point however I would suggest a fairly thin cro-mo pipe thats like 32mm diameter or so instead of that small bar/pipe

[jakel]

Cut up the steering column and all the shit around it save maybe 10-15kg:
http://www.ae86drivingclub.com.au/dcimages/5/3/7/71882.jpg

Sorry best pic i have of it. Then cut off all the random brackets that attach to the firewall (also seen in pic)

Also what i have done with mine aswell as remove sound deadner is scrape all the seam sealer off, like where the floor joins the sill panel(sides) and the interior side of the front wheel well, theres heaps of it on all the seams in the boot. If yout going extreme get the underneath of the car sandblasted so all of the undeside sound deadner is removed (The ruff shit in the wheel arches and such). Buy lighter rims and so on.

But its also about weight distro aswell. Put your fuel cell directly over your diff if you can, rather than against the rear panel. Put the battery inside/rearward of the car rather than the front, cut the original battery mount off. Anything or bracket/ mount you are not using remove it or move it rearward.

Pretty much exactly the way I will be doing mine as well.

[slydar]

its interesting that you think youve saved 10/15kg in the steering column bracketery... thats a bit more than i'd guess for a KE70. for an 86 there is a brace/mount that spans between the a pillars so it would be quite a lot larger saving for a hachi.

[fantapants]

d, do you remember mine at all with the 20v etc before i started pulling all the shit apart, it was 945 wet and less than a quarter tank.

i could have got it into the 800's with jap doors (15kg each), lexan rear windows and hatch (guestimate save 15kg?) alluminium exhaust ( saves about 10kg?) fuel cell (10kg) and random metal removal... say 20kg in total.

BUT id seriously recomend not doing doors till you have the cage man... its too risky. without the intrusion bars they fold like nothing else....

Also jumping the gun a bit, but spend the extra coin on a chromolly cage. Should be able to keep the weight of the cage down to about 45kg for complete welding cams approved. and that means you could realistically remove that much weight again in redundant metal.

Im hoping to do a shell in the coming year with a proper documentation through work of all the comings and goings starting with carm, bare shell weight, stripped weight etc etc etc.... think it would be good to get a legitimate idea..

also dont recon you would save fuck all from frp guards or roof skin.... metal is thin as fuck anyways...

bonnett is worth 10kg....

[slydar]

yeah. i have both types of doors to use if i want, but im pretty much decided. youre right there isnt much there in the jap doors, and maybe im testing fate, side impacts are pretty dangerous but..... its pretty much a track car, the likelyhood of a really serious side impact is pretty low. if i were to regularly drive/drift it on the street itd be different.

i basically want to build the car in a normal drift/time atack style first.

i will build my own cage and do serious chassis mods later. i dont think ill use chro-mo though. ive read a little bit about the pro's and cons and i dont think ill go that way, the weight penalty is minimal compared to the added complexity of fab'. to even consider it i'd wanna be pretty handy with the tig and sitting here right now i have 0 experience, but who knows where ill be up to when/if it eventually comes time.

[driftke70]

My loom out the rolla weighs in over 10kg, I would say closer to 15kg. So making a scratch loom is definately the go.
As for no windows, I am doing this soon just using those acrylic rain deflector things, stops your interior getting wet in rain, stops wind buffeting, weighs sfa.
185/60/14 on a 7 inch 3 piece is significantly lighter than a 195/55/15 on an 8 3 piece.
Tin in the doors is stronger than you think.
Definately over 5kg to be made in the steering column.
Single piece tail shaft would save a bit.
4age is definately a light motor when running aftermarket extractors and rwd water/no ps. I always felt like mine was almost too light.
Can trim everything off the back of the body that sits under the rear bar like dave did.
Cromo is a waste of time. DOM is where its at. Also I doubt my cage weighs 45kg. Its about 1.5kg a metre.

[fantapants]

curious why you recon chro mo is not the choicey choice beal?

in terms of weight, the complete cage we did for the boss car for targa series this year was 38 kg complete. Being a lamborghini its a little smaller in the cabin than the 86 so adding a few m of extra bars and gussets, 40kg would be about right for a very good cage.

We are about to complete a chro mo cage for another targa car, a escort cosworth. This has similar internal dimensions etc to the 86, but we are running approx 8 extra bars over the minimum required. This has come in at just on 50kg complete.

Agree that chro mo is a pain to work, BUT as far as i can tell, in the weight game it "might" be worth the extra coin time?

[driftke70]

cromo needs to be perfectly mated to weld and even then it is prone to cracking. Cant be painted otherwise you cant see the cracks, It is significantly more expensive. The dom steel I bought for my cage was around 400 with heaps left over. Cromo would have been in the region of 1500 or more. Also as dimitri said everything needs to be tigged, which is very time consuming and requires everything to be spotless. Some of my cage is tigged and its a pita.
So more or less no structual gain in strength, triple the price, has a shorter service life, for very marginal gains in weight. You will find most people who build cromo cages get carried away with way too many bars for some reason and end up with stupidly heavy cages. Cages need to be so much simpler than people make them. Simple maths and engineering principles can make 20% of the bars people use redundant. Obviously a targa car is going to have some pretty decent side intrusion, but thats about all i would change over any other cage. Even wrc cages are simple when you look at them from a balance perspective.

As far as I have heard also cams are looking to ban cromo. Or at least restrict its use as many "non professionals" are making dangerous cages with the stuff.

[driftke70]

also forgot to mention cages are supposed to have a bit of give, cromo makes them dangerously rigid and tend to crack before they bend

[fantapants]

yeah the engineering behind using a chromo cage is much stricter. And will continue to become more complex to do just as you mentioned, remove the backyarder from the danger to themselves.

However, while i see the validity of your argument re complexity of cages, this is now currently thanks to cams. The new regs involving a "basic" cage is, for all intents and purposes a full cage. It must have double intrusions, it must have doublt cross uder the main hoop etc etc etc. The basic cage doesnt pass the new regs.

as to marginal weight savings, thats what this thread is all about. Making the best of what is available in regards to weight management. Fwiw, generally speaking chro mo is about 1kg/m This varies a lot with the wall thicknesses that vary a lot more with chro mo building than dom tubing, so its a bit of an averaging figure accros the range of tubes used. This could equate to a saving of give or take 20kg?? Not bad in and off itself, however, needs to be looked at in terms of cost v return for sure...

The paint issue you mentioned is simply prior to painting the cage must be scrutineered to allow for visual inspection.

Your comment regarding chromo being too rigid is an over simplification i think. Chromolly in its pre weld state will NOT crack before bending. How else would you be able to bend the cage in the first place. ( not the best example i know as its a slow uniform bend not a sharp impact, but the basics are still applicable i think ) The issue is the heat affected zone. And as you so eloquently pointed out, this is dealt with by using good builders. I never really meant to suggest that dimitri do the cage himself, as i have no idea about his welding and tig specific skills. Hence why i suggested spending the extra coin on having a cams approved chromolly cage built for him. Sorry if it was not clear lol.

Also sorry for the offtopic, i was just really interested in bealy's opinions as its clear he puts stuff together well :D

[slydar]

should have a start on this in a month or two!

[killabeez_1985]

This all sounds like overkill to me. Unless your really competative spending the bucks on replacing whole panels with fibreglass or cf and cutting random sheets of metal off your car to save a few kilograms. Waste of time/money imo.

[slydar]

righto mate.

[Andy San]

On the subject of seats, those JAZ seats are the worst things I have ever seen, in both support and safety. They might be light but they are about as good as a plastic school chair. I would look at the kirkey alloy seats, which aren't much safer, but they are lighter and a lot more supportive.

[Rice86]

This all sounds like overkill to me. Unless your really competative spending the bucks on replacing whole panels with fibreglass or cf and cutting random sheets of metal off your car to save a few kilograms. Waste of time/money imo.

what he is after is what he needs..so its not a waste of time or money for him

[slydar]

i dont really see how the seats would be that bad, ive sat in them, im sure they wouldnt be great for a long distance road trip but thats not really what the car is built for.

they'de have to be lighter and at least as supportive as a stock seat. i have them already so ill be using them. as far as safety goes.. its the belt that holds you in place mostly in a crash, not the seat. they dont have much lateral support but theyll do to begin with.

re waste of time. im quite certain it is not.

what i have planned isnt going to cost much at all but im sure i can save substantial amounts of weight. i can tell you that even my current coupe, which should be lighter than a hatch spec fpr spec, with its full interior and sun roof seems less nimble and slower than previous cars. even a 50/60kg weight saving, which i should easily achieve you can easily notice. just think about the difference of having 0 extra passengers to 1.

[cssss]

just think about the difference of having 0 extra passengers to 1.

agreed

[takai]

How about you aim for a realistic weight then, <900kg wet with a full cage, 1/4 of a tank, and all OEM glass and panels is doable.

[slydar]

fair call but -

a. we havent really managed to work out a solid baseline.

b. as far as im concerned thats not all that ambitious, considering ..

c. i dont have any intention to initially build the car with a cage or stock glass.

the general idea is to reduce the weight as much as possible without resorting to spending a lot on frp panels etc, just to see what the weight (and performance) is like with a bare bones 86, with close to stock/mildly tuned 4age power.

[dying3k]

drill all the bolt heads out

[Delazy]

drill all the bolt heads out

Or just rock titanium...

[Sam-Q]

Cromo is a waste of time. DOM is where its at. Also I doubt my cage weighs 45kg. Its about 1.5kg a metre.

Whats DOM?

[Sprinter86]

Id be interested in ke weight compared to ae86, just weighed my ae71 panelvan recently, windows have been added in the back, full tank of fuel, 920kg.
sedan must be heavier than this, but are corollas lighter than sprinters??

[Delazy]

Whats DOM?

thanks to good ole wikipedia


"DOM"
Drawn-over-mandrel tubing is made from cold-drawn electrical-resistance-welded tube that is drawn through a die and over a mandrel to create such characteristics as dependable weld integrity, dimensional accuracy, and an excellent surface finish.

[takai]

So basically standard CDW.

[dying3k]

Or just rock titanium...

and still drill the heads out

[dying3k]

from memory acording to NSW RTA spec sheet a KE70 CS auto/no ac, is 940KG

[Rice86]

i dont care if Ke/ae71 are 500kg lighter, AE86 is a better looking car lol

[dying3k]

i only said that, as i havent looked in the book at ae86, i did it when i bought my nugget, ill look tomorrow if i remember,

[jakel]

They should be about the same, T18 is like 98x something its like 9kgs too light or something to ba able to engineer a 1uz in it!
(and no it doesn't matter what it weighs when done they go by factory gvm I am pretty sure.

[dehney]

how much do you save on when changing the rear hatch glass and ditching the fuel tank for a fuel cell ?

[mfxae86]

I run a decent street look oz spec 86 with what I consider to be reasonable weight reduction. I did this a while ago so im going by memory here.

My 86 came with a tow bar (yeah I know what for right?) it was ancient and incredibly over engineered at 21kg
Sound deadening was also a big one at 16kg not including the bits I had to wire wheel off or the silicone in the seams
Carpet and underlay was 5kg
ac and heating units under the dash was pretty decent as well but to be honest I can't remember the weight for those units maybe 8-9kgs
The tail end was rusted out so I body modded the panels under the rear bar a little only 1kg or so saving there but worth mentioning
frp panels - rear bar, front bar, front guards would save a bit, but probably level off when you add the side skirts and trd wing.
Under the bonnet was completely stripped and now running a 4agte with the bare essentials notable losses were alt cast iron bracket 3kg non essential wiring 2kg bonnet latch removed for bonnet pins

There is more but I can't remember, lol. and a little hard to measure out, all brackets for old hardware was drilled out, plastic liners removed... Just odds and ends I didn't need. im yet to hit a weigh bridge...

I think like most performance mods of any kind when you get started its leaps and bounds but eventually it comes to a point where the gains are minimal for the effort or cash spent.

Ok now on to the fibreglass tech bits. for those that don't know, I have worked with composites for well over 10yrs so I figure I could straighten out some of the conflicting thoughts on frp panels for you guys.
In most cases the frp gear available for most cars is NOT built to be light weight, it is purely cosmetic. Its made to be durable (usually 600gsm+) and is resin rich. Therefore its much of a muchness to have frp panels... Unless your running some thing old school like a HQ, lol.
On the other hand if the panels are built with the specific purpose of being light weight, using say 250gsm, spraying gel coat (as opposed to brushing) and using minimal resin and draining as much excess as possible or even better infusing, you can have a very light panel indeed.
The downside is that the product is flimsy and will break very easily in everyday life, taking a bump, leaning on it ect. and to top it all off it costs more to produce and buy.

I made the frp gear on my car quite a few years ago and the comparison would have only been a couple of hundred grams better on the fibreglass side outright, but if your counting every bit helps right ?

Now on to the composite roof theory, to be of similar strength as factory the weight would be similar particularly on such a flat area. it would only be viable if it were paper thin and perfectly produced in a woven strand (carbon etc.) and you would only be shaving grams... Think of it as a last resort type of thing... oh yeah and never discount cost.

just my 2 bob :)

[Sam-Q]

well I have to disagree with you on one point, the bonnet and fiberglass. A stock bonnet is 25kg, I have a top-stage drop vent bonnet that's 7kg. It's also so strong I can put a heavy box of crap on it without issue. I wouldn't be surprised if I could sit in the middle of it without any breakage.

[AJPS]

how much do you save on when changing the rear hatch glass and ditching the fuel tank for a fuel cell ?

fuel cells weight almost the same as stock tanks

and stock tanks are mounted lower and hold more fuel

[mfxae86]

well I have to disagree with you on one point, the bonnet and fiberglass. A stock bonnet is 25kg, I have a top-stage drop vent bonnet that's 7kg. It's also so strong I can put a heavy box of crap on it without issue. I wouldn't be surprised if I could sit in the middle of it without any breakage.

I did say in most cases, lol. Keep in mind the company that manufactures the product has something to do with it also.

As a reference I have handled many 180, silvia, skyline (list goes on) composite bonnets that outweigh the factory items, some of them "carbon". This also applies for guards bars boot hatches ect.
The point I was trying to highlight was that frp does not necessarily mean its lighter, and in most cases its not... It depends on the builder.

I don't think I explained myself correctly, my comments on product strength referred to the method I briefly outlined in my post. A very under engineered part that would easily break, but would weigh sfa. I just went from one extreme to another. The middle ground is where street automotive frp parts should be if produced properly, lighter but still durable for everyday life.

Im pretty sure 86 bonnets sit at the 14-15kg ? But your right, the bonnet you have has saved you a crap load of weight. I want one... now on my list of things to do :)

[Sam-Q]

I am sure it was 25kg, I have one around I should put it back on the scales.

Here's the weird bit, I didn't expect there to be a difference when I put it on, however I noticed a definate change in how quick the front of the car turned into corners. It wasn't big but definately there.

[Rice86]

I am sure it was 25kg, I have one around I should put it back on the scales.

Here's the weird bit, I didn't expect there to be a difference when I put it on, however I noticed a definate change in how quick the front of the car turned into corners. It wasn't big but definately there.

i second that, when i had the fiber glass vented hood, steering response was very good, and bonnet is very light, solid enough for everyday driving
put on a standard metal bonnet, straight away steering response was slower, not by a lot, but very very noticeable..

i would run fiber glass panel over metal any day of the week if i could afford to blow money on these parts (genuine parts), until then metal will do

[jakel]

Try making your own?

[Rice86]

i can make my own, but rather not for so many reasons lol