Dave Marshall
|
| posted on 15/6/12 at 06:56 PM |
|
|
750mc newbie questions
Hello everyone,
I've been building a Locost for the 750mc series for the last couple of years and it is now nearing completion. I'm hoping to get the car
out for the final few races of the season all going well and if the grids aren’t fully booked. The car is built and has had a shake down on a track
day at snetteton which went well. There are still a few things I'm not entirely clear on after going through the reg's and the blue book
numerous times though. Unfortunatly I haven't been able to make it to a meeting yet this year to ask some of the competitors. If anyone could
help me with any of the below it would be greatly appreciated?
1. I've read somewhere about the fuel line having to have a screwed connector at the carb, is this also the case at all connections. My fuel
pump and tank all have push on connections which would be difficult to change. Also, has anyone got any advice on what type of fittings to use for the
carb as mine is currently just the original push on fitting.
2. The car only just got through the noise test at Snetteton which was 105db I think. Are the noise limits at the races the same? If they are I will
need to repack my silencer, any recommendations on the best type of packing?
3. I've had to start from scratch with set up so I’ve hunted around on the internet for set up info for cars of a similar type, Westfield’s,
ect... I’m on 400lb springs front, 175lb rear. Ride height of 95mm front, 110mm rear, 3 degrees of camber up front. Running about 1.5mm of tow in but
really only guessing with that. Tyre pressures 23psi front, 21 rear.
Am I along the right lines here? I'm not asking for anyone’s set up secrets but don't want to get out there and be too far off the pace
and get in everyone’s way. The car felt pretty good to me on testing, but I've never driven a racing car before so I’m not in a great position
to comment!
4. I bought my tyres from a normal tyre centre a while back so they haven’t been scrubbed down as I believe most people do. Is it a great disadvantage
going into a race with fully treaded tyres? If it will be, does anyone know of someone in East Anglia who may be able to scrub them down?
5. And finally, does everyone run wheel spacers at the back. Doesn't seem to say you can’t in the regs and the tyres are very close to the
trailing arm bolts which I'm not totally happy with. I think I'll need longer studs to do so though.
I know it’s a lot of questions, hopefully there not to stupid. Any help on any of this would be great.
Thanks
Dave
|
|
|
|
|
ShaunB
|
| posted on 16/6/12 at 05:54 PM |
|
|
Hi Dave,
I'm based just down the road in Ipswich, so if you fancy a look over my car or me to come take a look at yours just shout. As for your
questions:
1) When it says screwed connector it is talking about the metal connector pipe in the carb itself. They were originally a press fit into the carb and
need to be swapped for a screw in connector. The fuel pipe can be a push fit onto this connector. The press fit connectors have been known to work
loose on a race car and hence it's a safety issue. My fuel pump has screw in connectors with push on fuel pipe and the tank connector is
obviously welded to the tank with a push on pipe.
2) Yes the limits are the same and measured at 3/4 max revs. There's nothing special inside my silencer just standard wadding and wire wool.
3) I ran stiffer springs than that last year but struggled to so soften the car enough in the wet. I've swapped to a set that are softer than
the figures you quote for this year, however it's not as simple as simply comparing rates as if your dampers are less upright than mine you will
need stiffer springs to compensate. If you found the car had a nice balance I'd leave alone for now - do you run an anti-roll bar as that will
also have an effect? My ride heights are a little lower than yours but by much, the important bit is to have the rear ~15mm higher than the front.
Be aware of the 50mm limit for the sump.
4) I've always used buffed tyres, although do have a new unbuffed set for very wet meetings. Nearly everyone buys from Polleysport, he attends
all the 750MC race meetings and also is often at Foxhall Stadium, Ipswich for their race meetings (but doesn't take the wheel balancer to those
meetings). He supplied my tyres pre-buffed.
5) They are allowed and a lot of people do. You will need longer studs and if you decide to remove the spacers you'll then need a deep socket
to tighten the wheel nuts.
The only stupid question is the one you did not ask 
Cheers,
Shaun.
|
|
|
Richard Jenkins
|
| posted on 16/6/12 at 07:49 PM |
|
|
Hi Dave,
There's a few of us a bit further north, Carl in Brandon, Rich.D & myself in Norwich, come to one of the meetings to say hello, we can
almost always find a spare ticket...
Shaun has pretty much answered as I would have done, the only things I'd add are:
1. You need a screw in connector at the carb and the hose pushes onto that and is held on with a jubilee clip. The ruling came in because someone had
a push fit connector into the carb and it came loose. You can guess what happened next...
2. I normally get measured at around 98db with an exhaust system from Aries Motorsport
3. Your spring rates and ride heights are pretty close to what I run. I don't run with any toe in though.
4. As Shaun said.
5. I have 1" spacers front & rear but to be honest I'm not sure they make a huge amount of difference to the handling, it does look
better though!!
cheers
Rich
|
|
|
ShaunB
|
| posted on 16/6/12 at 09:28 PM |
|
|
Forgot about toe and camber. I actually run slight toe out which gives a sharper turn in, I know of others that run parallel. Too much toe in can
lead to understeer. I set my camber by measuring tyre temps at the circuit and have only got as far as 3' on the NSF at Mallory where there is
a long fast 180 where you are leaning on the outside tyre for a fair few seconds. 1.5-2 is what I normally use. Tyre pressures are personal choice,
I'm currently aiming for 26-27psi when hot, and they gain 3-4 psi from cold.
Cheers,
Shaun .
|
|
|
Dave Marshall
|
| posted on 17/6/12 at 04:09 PM |
|
|
Thanks for the advice Shaun/Rich
The screwed connector being in the actual carb makes more sense now you say it. I’d got the wrong end of the stick. Luckily I haven’t done anything
with that yet. I suppose a 1/8 BSP taper fitting would be about the right size.
I’ll have to have my silencer apart and see what’s inside as it is re-packable. It’s a mild steel system made by Tony which he has apparently supplied
to locost racers in the past. I was a little surprised when it was so close to the noise limit.
I’ll have to have a play with the toe bearing in mind your advice as I hope to do another track day before my first race, hopefully at Donington as
that’s the first race I’m hoping to enter. I’ll try neutral and toe out and see what feels best. I’ll also take a little of the camber off I think and
take a temperature gun with me to see what the tyres are doing.
Shaun, it would be good to come down and have a look at your car sometime and have a chat. I’m also hoping to make it up to the first Donington
meeting at the end of the month as a spectator so may see you both there? I've also uploaded a few pictures of my car to the photo archive.
I’m just waiting to get my licence back now as I passed the ARDS on Wednesday. Then I can stick my entry forms in. Does anyone know how well
subscribed the grids are for the later races?
[Edited on 17/6/12 by Dave Marshall]
|
|
|
pointy
|
| posted on 17/6/12 at 07:40 PM |
|
|
Very nice car David.
I have sent a U2U that may be of help.
Andy (Another Norfolk Locoster)
|
|
|
Richard Jenkins
|
| posted on 17/6/12 at 09:13 PM |
|
|
Nice looking car, good colour scheme as well...
Sorry for not mentioning you Andy, but I thought you'd be too busy with your new build to log on! Was the U2U to Dave to ask how he'd
managed to finish his build so quickly???  
|
|
|
pointy
|
| posted on 18/6/12 at 08:12 AM |
|
|
Tee Hee Mr Jenkins.
The build is slow but sure.
Look forward to meeting up at Donny.
Andy p
|
|
|
andylancaster3000
|
| posted on 18/6/12 at 11:18 AM |
|
|
I had a double take when I saw the pictures on the top of the home page thinking someone had been picturing our car!
Car looks very tidy indeed. Looks like your own chassis too - good to see people building their own still.
Good luck with it - you have made a very good choice going with the Locosts!
|
|
|
procomp
|
| posted on 18/6/12 at 05:02 PM |
|
|
Hi
I have missed this posting. That's mainly due too not many use this forum anymore for communicating about the Locost championship. All the
official contact from both the 750Mc and the drivers Rep ( ME ) are now on the FB group which can be found here.
http://www.facebook.com/groups/179090942101754/414214601922719/?notif_t=group_activity
If there are any direct questions Etc regarding the Championship you can contact me directly on.
Email Matt@procomp.plus.com
Tel. 01213503258.
If you want a good honest evaluation of the suspension settings Etc just give me a shout as i sup[ply the majority off dampers and setup work for the
championship. Dyno testing off you existing dampers can also be carried out FOC.
The majority of drivers are running Rear- 120Lb - 150Lb springs rear toe and cambers can be setup but require the axle being modded to do so. Front
300Lb with ARB - 400Lb without ARB ( 350Lb without is good starting point. Front camber is determined by your camber loss / gain on your individual
setup so can not be just guessed at. Toe at the front ranges from 2mm in - 2mm out. Straight is never recommended as it's unstable. Ride
heights front and rear are determined individually by the different chassis ( yours home made ) so again needs looking at to determine best setup but
in general 4" under front chassis rail and then 1/2" rake to the rear gives good starting point with decent weight transfer during
cornering.
Cheers Matt
|
|
|
