Evening all,

Finally got round to weighing the Locost with the CBR1000F engine in the other weekend and was a little disappointed with result - just wanted to see if I'm worrying unduly. Did it 3 times.

1st measure - 548Kg
2nd measure - 547Kg
3rd measure - 546Kg

Weights were taken using 4 digital scales under each of the wheels and added together. Scales were Ebay specials so would say +/- 10% However checking my own weight against the expensive bathroom ones came out bang on the same - so seem reasonably accurate.

I weighed the engine when it was out earlier this year. Being the predecessor to the first carb'd Fireblade it's heavier at exactly 84.65Kg which is quite a lot for a bike engine I believe?

Just a little surprised by the total weight bearing in mind it's running no windscreen or associated paraphernalia/13" wheels/Fibreglass seats etc etc?

It did have a full tank of fuel - but from researching others posts on here - theirs were also weighed with full tanks and were coming out less. It does have stainless steel panels down both sides and rear tub however (not for long!). Surely it can't be adding that much weight?

Anybody think of something silly/obvious I haven't considered or is this actually about right for what I have?

Cheers
Tony

Tubular chassis, scuttle and roll bar?

Book Locost chassis, so box section. Roll-bar looks slightly higher than it should be though so good point on that one. Scuttle Fibreglass - bonnet aluminium.




Not much else going on in the engine bay :-




[Edited on 22/10/20 by Edwardo]

Ahh ok, was looking at your older pics.

Ahhhh right - yes that would be the horrendous Robin Hood 2B I was building prior to this

That seems Very heavy, as my ford xflow powered locost weighed 501 kg and that was weighed on four normal bathroom scales
I moved the scales around, the four wheels and always came within 500-503kg

The four scales total was around 600kg, so i was never close to a max reading

But, i did do an awful lot of weight saving,
The wiring loom, (home made) was absolute to the min
EVERY single bolt that was not critical was cut to the shortest possible length
every critical bolt as in suspension, had no more than three threads showing, i believe MOT standards are 2 threads showing

And i had a full carpeted interior

steve

What brake callipers are they? you also have a checker plate boot lid?, maybe just a case of chipping away?

Hi,
Stupid question perhaps, but how much fluid was in the car when you weighted it? Fuel, coolant, oil, etc. Weight difference can be huge between a dry and a completely filled car.

Keep weighing it..
It’s getting lighter every time, another 50 weigh’s will make a difference

Steel floor?

The SS side panels will be fairly heavy

What thickness steel did you use to build the chassis? Maybe around 20kg extra ish with 3mm vs 2mm box section over a chassis.

Are those wheels heavy?

Then again, you don't want it so light weight it falls apart or is certain death in a crash. To put it into some perspective, its still 450kg lighter than the curb weight of my tiny VW up which is the same length and a lightweight tiptop.

Thanks or the replies all.

I don't want to end up getting obsessive about weight like some people can - it's just seeing that Steve m's equivalent car with a X-flow engine and associated gearbox was nearly 50kg lighter def makes me wonder what's amiss here with mine as it should be lighter with a bike engine (one of if not the main benefit of fitting a bike engine of course). Out of interest, what does a X-flow+gearbox weigh?

I didn't build the chassis so not sure what gauge the box section is - I'm assuming standard book thickness but will def try and measure when it's stripped down over Christmas.

It does have a welded in steel floor

Cortina brake calipers

Each rim 5.48Kg (I weighed them before having the tyres fitted)

All fluids present and a full tank of fuel in the Mk2 escort van fuel tank it was built with (not sure how many litres - but looks pretty small).

Cheers
Tony

The M16 callipers are around 8KG the pair, you could save 6KG (ish) by swapping to HiSpec ultralight or similar.

My car had a steel floor, it was the roof off the mk2 escort

about a gallon of fuel, and all other fluids were in,

I had 4pot princess calipers, and they are a lot heavier than the M16 cortina ones

But my biggest weight saving from when i built the car was the tyres and superlight wheels, as all four were lighter than two the old 7j capri wheels with
big 205 tyres, and i used to have a spare on the back as well!

Also from memory, the boot was empty, so a bit of a false reading, as i always carried a gallon of fuel, oil, tools, jump leads etc and a spare engine!
(well bits of one)

steve

I think on my IVA application form, I put down 700kgs, 350 per axle. But at the test, they add the drivers weight, a passengers weight as well as two peoples luggage to get a top weight. They have asked me to change something on the paperwork when i go back, so am guessing my rear axle weights were quite a bit out sadly.
Mine is book, but with a steel floor, a full fuel tank and lots of lightened parts to try and help keep they weight down.

Oh and a x/flow similar to Steve's above.

Jason

[Edited on 23/10/20 by Deckman001]

I think initially it's probably just a case of doing the obvious ones for now then and having another re-weigh (chipping away as mentioned).

I'm sure that when I replace the SS side panels and rear with Ali - that will save quite a bit. Deneo recently made me a nice new fuel tank out of Ali too - so will be throwing the old steel Escort tank out. I suppose every little bit helps. I always planned to throw away the checker plate too (even tho it's already Ali) so that will all help.

It also has this boot section - which is very handy I have to say - but is also stainless with some thick insulation material stuck solidly to it with mastic :-







Even after all that I suspect I'll be lucky if it's down to 500Kg.

Hopefully I'll find a gigantic bit of lead wedged into the chassis somewhere when I start pulling it apart

That boot clad in armour plate, will be very heavy, mine was a simple pull out box thing, made from corex
(stuff that house for sale signs are made off) just doubled up in places and supported with a couple of aluminium strips,
the whole setup weighed precisely nothing !! and then a lightweight tonneau cover that covered the boot area

The stainless sides, you have also, are way over the top, (mine were 1.5 mm alui) but yours may of been done to aid in the rigidity of the home made chassis, so i think you should keep the sides, as you do not know whats hiding beneath

steve

It sounds ok to me, given some bike engines are lighter than that one, and it sounds like your materials are all the 'standard' ones i.e. steel & fibreglass, not aluminium and carbon fibre.

I think to get down to the 400-500kg range you're likely to need more aluminium in the floor and body instead of steel, and carbon instead of grp, then look at components and swap out to save the odd extra kg here & there.

So you have swap £££s for the lbs.....

Ad

To give a good reference.

Locost race car 750 book spec, Full cage ready to race X flow with 4speed box. 525KG

Our LA golds.Full cage Zetec type 9, ready to race 535KG ( with dry sump 9ltr oil etc etc 549Kg )

ST motorsport Locost. Full cage bike engine 919 blade, ready to race no expensive carbon bits just built light INC reverse. 450Kg

Thanks Procomp - Good grief, I'm a mile off then!! Gotta find best part of 100Kg from somewhere?!

Maybe a previous builder injected concrete into the frame

Dead body hidden somewhere? Is there a smell?

It's about the correct weight for a BEC with a square box section chassis in road going spec.

Unless you are going to race it it's not worth worrying about.

Although saying that that engine is pretty heavy for a bike engine with lowish BHP.
If you feel it's not powerful/fast enough you would be better off going for a higher power bike engine rather than trying to lighten the car imo.
Iirc my R1 engine was 58kg and produced 150bhp on the RR.

According to the internet the fuel tank from a mk 2 escort van is 12 gallons and made of steel.

12 Gallons of petrol weigh approx 41kg + tank 15, vs kit car tank about half that and half the fuel. So 25l ally tank + fuel + remove the soundproofing stuff round the tank and you probably cut of 30kg

Regards
Hugh

Thanks again all - Slight update

As the weather was ok Sun lunchtime - took the car out for it's last spin and to test the new MK gear lever I fitted which has taken out all the slop and feels great.

Took it steady for 5 mins to warm her up, then when pulling out of a side road - gave it some beans. Back end sat down and a fairly loud 'CLUNK' from behind me. Eased off but seemed ok so assumed the new gear lever must have touched the prop or something. Coasted up to the speed bump in the road and went over it slowly. Very loud 'CLUNK'! from behind me. Pulled away slowly and the car felt like it was trying and jump out of gear every few seconds with a thud.

Pulled over and got the nice lad up the road to come tow me back. Jacked it up and took the back wheels off :-

O/S lower suspension bracket snapped:-



N/S lower suspension bracket snapped :-



What a quality design these live axle suspension mounts are At least the brackets have been welded to the infill panel so were at least still hanging on in Cantilever.

So that obviously settled it for when to start the Winter teardown lol.

[Edited on 26/10/20 by Edwardo]

[Edited on 26/10/20 by Edwardo]

So first thing to get ripped out was the rear checker plate boot cover/boot itself and side infill panels :-







The checker plate lid + lock was 2.3Kg
Checker plate lid surround was 1.7Kg
Stainless+wood boot = 6.7Kg
Painted Side Cover Plates (1.6mm thick stainless!) = 0.75Kg each

So just ripping that lot out has saved approx 12.5Kg thus far.

I can now see the fuel tank and the other horrible roll bar welding (being polite) which isn't to the book :-

I had one of the links break on my chassis as well, my cure was to butt weld another small piece of Rhs to double up the mounting behind the u bracket
so that the whole bracket was supported, and not just on half its side, never had an issue afterwards

Glad you cut out all that wasted tatt from the boot, just make a lightweight box for the boot, and a tonneau cover with poppers,

steve

Judging by the rusty stains around those mounting points it looks to me like a lack of maintenance.

What type of bush is used in them?

If it's a poly bush there is a good chance they have seized up judging by the rusty stains,and that's caused the brackets to break

Good question - I've not removed the suspension arms yet as I was still messing around with the back end and getting the old tank out last night.

I've only had the car since Feb - but judging by some of things I've discovered I don't think many of the previous owners were particularly hot on maintenance so it could well be that the bushes are seized.

In fact, I hope you're right actually as that would at least explain it. Previous owner told me him and his Brother used to drive it to a track - thrash the living ** out of it for the day/drive it home and leave it till next time. I've been out in it for a few gentle (by comparison to a track day I mean) local runs and the suspension breaks lol?!

I'll post up the weight measurement results of the fuel tank later.