Custon Build - FS Style Track Car
Discussion
SammyW said:
Great looking build. Fancy doing something similar myself but dread to think how long it would take on my own knowing what went into the FS car I helped with at uni. Do you have any sort of time frame?
The Original plan was to finish the whole car by the end of this summer (I'm currently on a gap year) but time has run away, as it always does, so i'm going to have to find a garage i can rent when i go back to uni so i can finish over the next few years - progress will be much slower with full time studies to consider.escort90 said:
Have you thought about your brake layout?
yeah - there's a photo attached of one of my uprights - these were a real pain to design, it went through in excess of twenty re-designs in order to minimize size and weight. they're still fairly heavy, but not an area i wanted to skimp on materials in - car should do in excess of 100mph, and i really don't want to be loosing a wheel at that kind of speed.
what you can see is - Top image: outside side, mainly dominated by the hub - a 60mm thick solid ally element turned in a high precision workshop - recess in the middle for weight saving - there's still four holes to go in it - in between the brake disc bolts for the wheel bolts.
Bottom Image:
ally upright, with bearing flange (bearings currently not fitted - they've been made from simple symmetric shapes so the the left/right parts are identical - therefore easier and cheaper to produce, and they can be swapped out side to side. the very central shaft is the Axel, which is the same single piece of metal as the hub - there will be a high tensile strength put down the center of the Axel to retain everything (again, hole yet to be drilled)
the rear brakes will be fitted to mini-shafts on either side of the diff - this allows me to use equal length half shafts an cv joints down to the rear wheels - there are no designs yet - just rough ideas in my head for the rear of the car - probably a machined ally bulkhead holding diff, calipers, shocks, and the top wishbone components - this will make it a pain to design, and doesn't allow movement to get the appropriate chain tension - thinking about using a trailing tension wheel to keep the tension in the chain - (a bit like the rear derailleur on a mountain bike, but secure-able, rather than spring loaded - unless anyone has a a better ideal on this problem?
This has been designed for the purpose of the FSAE event: http://www.torsen.com/fsae/fsaefaq.htm
It has a fair bit of information on there about weights, dimensions, torques etc. You would have to ship it from the usa so I think it was roughly $400 before shipping, but I have no idea how much it would cost to ship it too the UK
About the brakes, have you thought about using just one inboard brake on the rear? My team justified using just one as it would be lighter and would have been more than sufficient at race speeds. Obviously you'd be going a fair bit faster than race speeds but I would have thought you would ok still as it would be a very light car.
It has a fair bit of information on there about weights, dimensions, torques etc. You would have to ship it from the usa so I think it was roughly $400 before shipping, but I have no idea how much it would cost to ship it too the UK
About the brakes, have you thought about using just one inboard brake on the rear? My team justified using just one as it would be lighter and would have been more than sufficient at race speeds. Obviously you'd be going a fair bit faster than race speeds but I would have thought you would ok still as it would be a very light car.
Edited by escort90 on Sunday 17th April 14:51
This could be a usefull website for you in terms of layouts etc: http://www.dpcars.net/
Im not sure if you've seen it before but he has designed and is currently building a range of motorbike powered cars and has had to overcome a few problems which are similar to those found in the FS car.
Im not sure if you've seen it before but he has designed and is currently building a range of motorbike powered cars and has had to overcome a few problems which are similar to those found in the FS car.
escort90 said:
This has been designed for the purpose of the FSAE event: http://www.torsen.com/fsae/fsaefaq.htm
It has a fair bit of information on there about weights, dimensions, torques etc. You would have to ship it from the USA so I think it was roughly $400 before shipping, but I have no idea how much it would cost to ship it too the UK
About the brakes, have you thought about using just one inboard brake on the rear? My team justified using just one as it would be lighter and would have been more than sufficient at race speeds. Obviously you'd be going a fair bit faster than race speeds but I would have thought you would ok still as it would be a very light car.
That diff looks like a winner - I'll have a really good look into it over the next few weeks, but looks promising - thanks very much for that.It has a fair bit of information on there about weights, dimensions, torques etc. You would have to ship it from the USA so I think it was roughly $400 before shipping, but I have no idea how much it would cost to ship it too the UK
About the brakes, have you thought about using just one inboard brake on the rear? My team justified using just one as it would be lighter and would have been more than sufficient at race speeds. Obviously you'd be going a fair bit faster than race speeds but I would have thought you would ok still as it would be a very light car.
Edited by escort90 on Sunday 17th April 14:51
The two brake setup I'm currently thinking of would comprise inboard units, be criminal not to with the style of design - minimize the upright, unsprung weight and all that.
I did originally want to have a single unit on the back, but if you do that it needs to mount directly to the diff rather than any part of the axel(otherwise it'll only brake one wheel) and with the sprocket already on the diff it seemed like a bad idea - How'd your uni get around it? or do you have it on one side of the diff and rely on LSD style system to brake both wheels? - i had real problems getting my head around how a TORSEN diff works - had to build one out of Lego Technic to see. clever stuff.
Just thought I'd share this with you:
Bought some high tensile bolts today (M14 x 80 x 1.5) for mounting my wheels to the hubs - got them from an ebay shop - figured when I rang to give payment details for the bolts I'd just ask them to throw in some lock nuts a bill me the extra; good job I checked the price first:
Here's the unbelievable bit - bolts £25 for 16 - reasonable I though,
lock nuts - £30 each. EACH.
That's £480 for 16!? wtf!? for that price I'd want them to be made from gold that had come from the queen's crown and lovingly hand filed by virgin supermodels, kissed and blessed by his highness the stig, then delivered by helicopter, preferably with supermodels in tow. How can you justify £30 each?
Bought some high tensile bolts today (M14 x 80 x 1.5) for mounting my wheels to the hubs - got them from an ebay shop - figured when I rang to give payment details for the bolts I'd just ask them to throw in some lock nuts a bill me the extra; good job I checked the price first:
Here's the unbelievable bit - bolts £25 for 16 - reasonable I though,
lock nuts - £30 each. EACH.
That's £480 for 16!? wtf!? for that price I'd want them to be made from gold that had come from the queen's crown and lovingly hand filed by virgin supermodels, kissed and blessed by his highness the stig, then delivered by helicopter, preferably with supermodels in tow. How can you justify £30 each?
From what remember brake wise, we used a single disc acting through the diff. Yes it saved some weight but we had alot of problems with overheating and also passing the brake test (less of an issue for you).
I think also only braking one side the other wheel could still rotate half a turn until the diff caught up and started braking the whole axle, made things a bit unstable.
I think also only braking one side the other wheel could still rotate half a turn until the diff caught up and started braking the whole axle, made things a bit unstable.
ady_GTi said:
From what remember brake wise, we used a single disc acting through the diff. Yes it saved some weight but we had alot of problems with overheating and also passing the brake test (less of an issue for you).
I think also only braking one side the other wheel could still rotate half a turn until the diff caught up and started braking the whole axle, made things a bit unstable.
I think I'll be using a twin brake set up on the back then - one each side of the diff on custom Axel extensions; should be more stable. The weight isn't such a problem as i don't have a restricted intake, so there's more power to go around. I think also only braking one side the other wheel could still rotate half a turn until the diff caught up and started braking the whole axle, made things a bit unstable.
Think I'm going to try and make it road legal - I've finally got hold of the test criteria from the DVLA, doesn't look too hard (but it will be a huge pain in the arse). Think the main issue at this point will be the noise - it currently sounds like god gargling gasoline (awesome sound, but a touch on the loud side). And, yes, the wheels do need covers - 30 degrees forward, 50 degrees back. Also needs a reverse gear!? could be a problem with a sequential gearbox? I've thought about having a starter motor that engages directly onto the chain for a reverse gear? just needs to move backwards under its own power to pass. Anyone got any more creative ideas? must be light though, no reversing boxes or anything.
As for the bearing seals - they're not in the photo of the assembled upright, because the bearings aren't either. They need pressing onto the hub - and that'll make them difficult to remove. It will be fitted with seals - tapered roller bearings really need quite a lot of grease due to the large contact area and the high revolution speeds.
As for the bearing seals - they're not in the photo of the assembled upright, because the bearings aren't either. They need pressing onto the hub - and that'll make them difficult to remove. It will be fitted with seals - tapered roller bearings really need quite a lot of grease due to the large contact area and the high revolution speeds.
Edited by StudentMike on Wednesday 27th April 19:29
Re. reverse gear, alot of the kit car boys use this method, I think the kits are approx. £350 but thats for prop driven. Can you make up something that engages onto the chain drive?
Just thinking out loud... if its going to be road legal it will need an alternator, does an alternator work like a starter motor if the current is reversed? Is it possible to use it as an alternator when travelling forward and then reverse with it, drawing power from the battery, so it acts as an electric motor?
Just tell me if this is a stupid idea please
Just thinking out loud... if its going to be road legal it will need an alternator, does an alternator work like a starter motor if the current is reversed? Is it possible to use it as an alternator when travelling forward and then reverse with it, drawing power from the battery, so it acts as an electric motor?
Just tell me if this is a stupid idea please
GreatGranny said:
Re. reverse gear, alot of the kit car boys use this method, I think the kits are approx. £350 but thats for prop driven. Can you make up something that engages onto the chain drive?
Just thinking out loud... if its going to be road legal it will need an alternator, does an alternator work like a starter motor if the current is reversed? Is it possible to use it as an alternator when travelling forward and then reverse with it, drawing power from the battery, so it acts as an electric motor?
Just tell me if this is a stupid idea please
Great lateral think there GreatGranny, ANY ideas are always worth a mention - I'm a bit of a lost cause when it come to electrics so i can't tell you if the alternator could be used as a motor for reversing. However: I'm pretty sure that to reverse this type of car (i.e. no reverse gears in the gearbox) you'd need to drive the chain/rear Axel - if you used the alternator in reverse (or any other part of the engine in reverse for that matter), all the internals of the engine would also run in reverse, effectively turning the exhaust into an intake and vice versa, effectively stopping the engine from working, thus, no power. Just thinking out loud... if its going to be road legal it will need an alternator, does an alternator work like a starter motor if the current is reversed? Is it possible to use it as an alternator when travelling forward and then reverse with it, drawing power from the battery, so it acts as an electric motor?
Just tell me if this is a stupid idea please
Again - great lateral thinking though. Top job!
I was thinking of making a lever-type system that engages the started motor directly onto the chain - then having a button to start the juice flowing. Would look a bit like a hand brake i think. or possibly having the motor permanently engaged, but on some type of free wheel? haven't really got into the nitty-gritty of it all yet, but it's certainly a major obstacle.
Starter motors have a "throw-out" type engagement anyway. They don't run permanently engaged on the ringgear in a car, but the gear on the end shoots forward on a solenoid when it receives current. That means you can permanently mount the starter, and it will engage itself on the drivetrain just with a button press, no need for levers etc. Excellent project by the way, shows the difference between a skilled mechanic (me, on a good day!) and a clever mech eng (I have the right bit of paper but couldn't do what you're doing!).
aww999 said:
Starter motors have a "throw-out" type engagement anyway. They don't run permanently engaged on the ringgear in a car, but the gear on the end shoots forward on a solenoid when it receives current. That means you can permanently mount the starter, and it will engage itself on the drivetrain just with a button press, no need for levers etc. Excellent project by the way, shows the difference between a skilled mechanic (me, on a good day!) and a clever mech eng (I have the right bit of paper but couldn't do what you're doing!).
Thanks for the support!Is the gear from the started motor permanently engaged and the solenoid pushes a dog-tooth or clutch engagement when the current comes, or does the gear physically disengage form the ringgear?
Want to mount the starter motor to the chain ideally, but if the gear does disengage then that won't be possible. Don't really want a ringgear on the rear axel - too cramped with the inboard brakes as it is - (or will be more to the point). Do you think the starter motore will have enough grunt (or ratio) to handle a direct chain engagement?
Edited by StudentMike on Thursday 28th April 20:06
I think it's more common for the gear to move in and out of contact with the ring gear, the ones I have seen have very bevelled profiles on the starter teeth to aid engagement. I only work on older cars though, so my experience is far from exhaustive! The guys on the kitcar forum here, or on locostbuilders.co.uk will be happy to help I'm sure, they will have found many different ways of doing this on BECs.
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