has anybody here built their own kitcar?

[mathew]

i watched some cr***y tv car show the other day and they had a MEV Rocket on there. id never seen one of these before and fell in love with them straight away. i then went straight online to find out more about them. turns out they arent that expensive to build and seem pretty straight forward (he says in a naive tone). how much skill is required to build your own kit car and s it possible for someone like myself, with limited skills, to achieve such a feat simply by following instructions?

 

for anyone thats never seen a MEV Rocket heres a little vid

 

[Chris Wilson]

Pete has. My advice, buy a factory demo car, kits NEVER go together as the build manual would have you believe. Better still, buy something more tried and tested like Pete's, a Caterfield or an Atom. Best, look at the weather and decide how much use this thing is REALLY going to get, how much it will cost fully done, tested and taxed and insured, and go buy a proper car form the Bargain section of Autotrader

[ADL Mark]

My friend's Dad has been slowly building a Fisher Fury for about a year now. It will be a lovely car when it's done, but the kit is awful. From the lack of instructions to the enourmous amount of things that weren't done right (welds) or didn't fit (gearbox mounts, steering mounts, suspension mounts) it's been quite a struggle.

 

Had it not been for the fact that he's a very experienced mechanic, one son is an army-trained welder and the other is an engineer I think it'd have been nigh on impossible. Certainly to any half-decent standard.

 

It's put me off having one myself due to the work involved, I'd buy one ready done.

 

Unless you've got the money to waste on a Caterham which probably will fit together (vastly overpriced though), then don't bother.

[j_jza80]

Looks nice that MEV, reminds me of a BMW conceptcar from the 90s (the name escapes me though...)

As has been said, these kits can be a nightmare. The factory demos are generally relatively well screwed together.

[JustGav]

Pete has. My advice, buy a factory demo car, kits NEVER go together as the build manual would have you believe. Better still, buy something more tried and tested like Pete's, a Caterfield or an Atom. Best, look at the weather and decide how much use this thing is REALLY going to get, how much it will cost fully done, tested and taxed and insured, and go buy a proper car form the Bargain section of Autotrader

 

AGREED....

 

They are brilliant to drive BUT the build side is tricky as hell. The books make it look so easy, but then you have to factor little things, for example...

 

The chassis built of box tubing... during welding it expands throwing it out slightly, and all this little changes do add up and you don't always get a straight chassis. Yes it can be done, we built up a jig in order to do it properly, that alone is a fair amount of work.

 

Getting it tested is a WHOLE different ballgame as there are so many little niggly things that you will get caught out with.

 

Don't for one second believe you can do it for the Ron Champion claim of £250, it doesn't happen. Tubing alone cost me in excess of £100, and that is without anything else.

 

I'd be loathed to buy someone's home built chassis as well as you have no idea on the welder's skill or work and lets be honest you are sat in a tube frame without knowing what will happen.

 

Sooooo many gotchas with this sort of thing...

[michael]

I think that TV tool Mike Brewer built one of these (or pretended to) with the help of a local garage, that alone would put me off.

 

I'd rather invest the cost of the kit and time spent back into the donor Focus and make it into a mild tarmac spec rally car. But then I'm odd like that.

[Thorin]

Caterham and Westfield build documentation is apparently second to none, most of the rest is spotty user forums support at best. I think Pete would probably tell you the same.

 

I've done a fair bit of looking into kit cars and I'm looking at buying a Westfield this year hopefully.

[JustGav]

Personally, if you want something different, get a kitcar and drop a forklift electric motor into it

[lexsum]

what a let down - the name is a complete misnomer!

[Pete]

Pete has. My advice, buy a factory demo car, kits NEVER go together as the build manual would have you believe. Better still, buy something more tried and tested like Pete's, a Caterfield or an Atom. Best, look at the weather and decide how much use this thing is REALLY going to get

Agreed, I did think it was going to be easier than it was...but then I wouldn't have learned so much in the process.

Don't forget to factor in the price of decent tools, hiring of engine hoists etc. I didn't have many and this was a considerable hidden cost for me.

Many parts in my Tiger kit were cheap and nasty - so I opted to replace them with higher quality parts. They were fine to take these parts off the price from the offset.

As Chris says you're better off going with a long standing brand that's fettled the models over the years and is likely to have a strong members club.

Caterham and Westfield build documentation is apparently second to none, most of the rest is spotty user forums support at best. I think Pete would probably tell you the same.

Indeed you do get what you pay for. I could've spent another £4-5k buying a Westfield which would've got me a technically superior car, but I had to offset that off the actual usage it would get as a hobby. I couldn't justify that extra cost for what was ultimately the same driving experience.

Incidentally I went to Westfield (not far from me) and after thinking hard about it explained to them why I didn't choose one of their vehicles. I just didn't feel it was good value for money compared to the Tiger. Oddly enough about two months after they launched a new advert and a tweaked offing under the strap line "Great value for money".

 

The Tiger OC is great with people on there offering tons of advice and will bend over backwards to help you out, send free parts etc.

 

The best thing of all is the feeling of achievement afterwards. To say you built your very own car and thrash it around a track is a feeling hard to beat.

[johnd-mkiv]

I always wanted to build my own Kitcar, but after speaking to a few people the SVA test was putting me off. I had a look on ebay for a few months and come across this already SVA tested but needing a load of work.

 

I spend a year and a half to finnish it but most of it made easy due to it being at my work and having all the tools I needed to hand. I would say have a go if you can get a kit cheap enough, that if you get bored and want to sell on you wont loose out at least you had a go. The bits that took the time were the little brackets, trim parts ect that need to be taken into consideration. You will need a fair amount of tools to complete one. There also loads of forums and books to help you along. good luck with it

[mathew]

plenty of info so far, thanks guys!

ideally i would prefer a second hand one that needs a bit of work, like yours john, rather than myself carring out a complete new build. i see a lot have a 2.0 pinto engine, what sort of performance figures are we looking woth this engine?

had a passenger ride in a road legal buggy today, was a great laugh, and that has really got me thinking about one of those instead of a kit car now though

[snake]

Don't forget if you're a big guy get the wide body version, as there is not alot of room in

A westfield.

[Kranz]

Wide body Westfield Seight 3.5 V8 with Janspeed T4 twin turbo kit (not fitted yet as I don't have the balls) anyone??? lol

 

Only 850 miles on it......

 

[Thorin]

Wide body Westfield Seight 3.5 V8 with Janspeed T4 twin turbo kit (not fitted yet as I don't have the balls) anyone??? lol

 

Only 850 miles on it......

 

http://seight.com/images/owners/cranswick.jpg

 

Go on then I'll take it off your hands.

 

 

 

I'm seriously looking into this again at the moment (well I do potentially have a large redundancy payout coming!). While I've got people's attention on here (CW hopefully!), I got looking at the MK Indy R chassis with it's fancy in-board suspension setup (I think the Raw Striker also uses a similar layout?).

 

 

Thoughts? I'd like to get a closer look at the layout around the front there (radiator placement etc.). I'm just wondering whether it's worth it or not, it'll be mainly used for track days with the odd pootle about in the summer when it's not raining.

 

I think I'm probably going to be looking at either building something up from a rolling chassis or buying something ready built but that I can learn from by uprating the brakes/suspension etc. as I go along.

[Guest Garfy]

I feel like I'm building a kit car with the mx5, lol!!!!

[RobSheffield]

Wide body Westfield Seight 3.5 V8 with Janspeed T4 twin turbo kit (not fitted yet as I don't have the balls) anyone??? lol

 

Only 850 miles on it......

 

Go on then, how much?

[Chris Wilson]

You don't want the MINIMUM camber change like that! Nothing wrong or unusual in pushrod rocker suspension, it's been common for years in all sorts of cars.

 

CAMBER RECOVERY

 

What conditions should we design camber recovery for?

^

It may seem simple to say roll at maximum anticipated g but usually we are just off the brakes at this point and the chassis will not have fully returned to normal ride height.

^

I am also confused that some experts recommend max roll plus 1" bump on the loaded wheel - gives great results for camber recovery but is it really relevant? - I am struggling to see the justification unless there just so happens to be a bump at a fortuitous point!.

^

Is there perhaps a sequence of chassis attitudes we can consider as the car progresses through the corner?

 

With independent suspension, for all applications other than the outside wheels in a highly banked turn, we can't get the camber recovery we want. We get what we can, without producing excessive camber change in conditions other than roll.

 

Some definition of terms is in order.

 

Camber is a tire or wheel's lateral inclination relative to the road surface, toward or away from the vehicle's longitudinal centreline, often denoted by φ (phi). Camber is conventionally positive when the top of the tire tilts outboard.

 

Inclination is a tire or wheel's lateral inclination relative to the road surface and to direction of travel, often denoted by γ (gamma). Inclination is conventionally positive when the top of the tire tilts to the right, as seen from behind. We may also speak of inward or outward inclination. Inward is toward the turn centre. Sometimes inward inclination is taken as positive, which makes some sense, although it conflicts with right-positive sign convention if we are turning left.

Camber gain is the rate of camber change with respect to suspension displacement, as measured by moving the suspension, usually with a jack, with the car stationary on the shop floor. This quantity can be an instantaneous rate of change at a given point in the travel range, or it can be taken as the change over a chosen interval of displacement, such as the first inch of compression from static position. Camber gain is generally taken to be positive when the camber change is toward negative as the suspension compresses.

 

Camber gain is directly related to front view swing arm length. For a front view swing arm length of 180/π inches, or approximately 57.3 inches, camber gain is one degree per inch. Camber gain is inversely proportional to swing arm length. If swing arm length is half of 57.3", or 28.65", camber gain is 2 degrees per inch. If swing arm length is twice 57.3", or 114.6", camber gain is 0.5 degrees per inch.

 

Camber recovery refers to the suspension's ability to make the wheel lean less than the car leans, when cornering. Most commonly, camber recovery is expressed as a percentage, usually the difference between camber change and roll, divided by roll, times 100%. When discussing this purely in terms of suspension geometry, it is common to ignore deflection effects in the tires and other parts.

 

So if the geometry is such that camber changes at half the rate that roll displacement changes, that's 50% camber recovery. If camber doesn't change at all with roll, that's 100% camber recovery. If the wheel actually leans into the turn as the body rolls outward, that's more than 100% camber recovery. If the wheel leans the same as the body, that's zero camber recovery. If the wheel leans more than the body, that's negative camber recovery.

 

It is most common to consider camber recovery in pure roll, but it is also possible to look at a combination of roll and ride, and calculate camber recovery for that condition.

 

If we didn't have to worry about any other effects, ideally we would like the tires to be upright when running straight, and lean into the turns a degree or two when the car rolls in cornering. We would like the inward inclination to be sufficient to compensate for roll due to tire deflection, plus another degree or two. We can have no camber recovery for the tire deflection component of roll, because it involves no suspension motion. For example, a go-kart has no suspension other than tire and frame deflection, but it rolls a little bit on its tires. The wheel inclination always changes in an outward direction with this roll, by an amount equal to the roll angle. There is a similar tire deflection component to roll and camber change when we do have suspension.

 

The tire makes best cornering force with some inward inclination, so we would actually like well over 100% camber recovery.

 

But we can't get that, or anything close. To get even 100% camber recovery, the front view swing arm length needs to be half the track width. For a 57.3" track width, this implies that in any condition other than roll, camber will change 2 degrees per inch of suspension displacement. That's basically the camber change rate of a swing axle suspension. To get 150% camber recovery,

the front-view swing arm length needs to be 1/3 of the track width. The camber change rate then would be 3 degrees per inch. Camber changes, as the car brakes or goes over humps, dips, and bumps, are unacceptably large when the front view swing arm length is that short.

 

So the game is not one of getting ideal camber recovery and letting other properties fall where they may. Rather, we have to strike a compromise between camber control in roll and camber control in other situations. We have to decide how much camber change we are willing to tolerate in ride – or in pitch, heave, and warp – to reduce camber change in roll. With long swing arms, we have poor camber control in roll, but good camber control in the other modes. This produces a forgiving car, which also stops well and puts power down well in a straight line. This comes at a cost in ultimate cornering power.

 

There is one way to get better camber control in all modes at once: widen the track, and increase the swing arm length by a smaller percentage than the percent increase in the track. Of course, there are penalties in other areas when we do that. In racing, we will generally be constrained by either a track width limit or an overall width limit in the rules. In autocross and hillclimbing, we may not

have a width limit in the rules, but we will want a reasonably narrow car due to the tight confines of the course.

 

Independent suspensions on banked ovals present a special case. There is so much "dive" or ride compression, that it is actually fairly easy to get more than 100% camber recovery on the outside wheel when the ride motion is included. Quite often, the inside front suspension actually compresses, meaning that to get camber recovery there, we need an instant centre to the left of the car, and negative camber gain.

 

Current NASCAR setups are a further special case of the special case. The suspensions are designed to create maximum downward jacking, with little regard for camber recovery. The front end is intended to jack down to the bump rubbers on the first turn, and be held down on the rubbers even on the straights for the rest of the run, by a combination of aerodynamics and shock valving. The suspension is very nearly immobilized when the car is at speed, so camber recovery is not much of an issue. The static camber is set to whatever provides desired running camber once the front end is on the rubbers.

 

The reason this approach works is that the cars run at high air speeds, have splitters that work best when they are near the road, and yet have to drive over a barrier to get through tech. If it weren't for the ground clearance rule, the teams could just set the car at whatever height they wanted statically.

 

The cars often actually have negative camber gain on the right front wheel: front view instant centre to the right of the car. The idea is to get a force line sloping below ground toward the middle of the car, to maximize downward jacking with lateral force. This could theoretically also be done with an instant centre to the left of the wheel and below ground, but I guess this is hard to do with the

 

spindles the rules require. The left front has an instant centre to the right of the wheel. The idea there is to get the smallest possible spring-to-wheel motion ratio, again to try to get that corner of the car down to the bump rubber and keep it there. It would be possible to just use a softer spring, or make the motion ratio at the lower control arm smaller, but again the rules get in the way.

 

So we end up with a front end whose camber control characteristics are diametrically opposite to what we'd want if the suspension worked normally at speed, just to work the peculiar rules. This illustrates what profound and counter-intuitive effects can arise from seemingly simple rules.

 

It's also a classic case of "any suspension will work if you don't let it."

[JustGav]

Nice bit of info there, cheers for that

[Thorin]

Yes, thanks for that Chris. Interesting stuff, I'm learning!

[AndyT]

Phew. Had to read that three times to pick up even the basics.

 

Love the SEight.

[Thorin]

Phew. Had to read that three times to pick up even the basics.

 

Love the SEight.

 

I don't pretend to understand all of it, and it took me a couple of read throughs!

 

 

Are there any good books on suspension design/setup etc.?

[AndyT]

I don't pretend to understand all of it, and it took me a couple of read throughs!

 

 

Are there any good books on suspension design/setup etc.?

 

Just had a look at Amazon. There's loads Wouldn't have thought so much would be available.

We need Chris to tell us which one's are good now though.

They're all about £20 too.