MX5 based build thread

[CJ27]

I'll start by introducing myself, having been using the forum for a few years now I've only recently registered, my names Chris, 28 and residing in Warwickshire.

The forum has been a wealth of knowledge whilst planning my build, using your posts and threads to evolve my build in my head before finally getting stuck in.

I figured now is as good a time as any to begin my roadster build, having recently finished my Mini project I found my self with an empty workshop and a yearning for a challenge to evolve my engineering and mechanical skills some more.

I purchased a chassis kit via ebay around 6 weeks ago, needing to clear the workshop out and sort my build table, it's taken until today to actually unpack it and get started.

I plan on building an mx5 based chassis, utilising the Mazda suspension and steering but going for the ford duratec engine, coupled to the mk3 mx5 gearbox.

Well that's the current plan, I'm sure as things unfold it will change some what.

So I started my build table this morning, I managed to knock it up in about an hour, using wood I had in stock and 25mm mdf board as the surface, it's worried out well and I've been able to free more space by utilising the area beneath the table.

Once this was done the kit was unpacked, I seem to be a few bits missing, mainly the front frame tubes, I've sent an email for clarification and to see if I can get it sorted. Luckily I purchased a part kit some years ago from a chap on ebay and I have a front frame and some spare tubing to get on with.

Build table up and the kit unpacked
http://i181.photobucket.com/albums/x47/f70-ryp/acbcbcbdd4c01df30934dd4517c446bb.jpg

I sorted all the tubes into sections (base, top, uprights etc) and began to mark out the general layout and get the base rail lined up and tacked together.

http://i181.photobucket.com/albums/x47/f70-ryp/4ce1793b7ce52b307c0b7bbe339e8826.jpg

Working slowly through, checking three or four times my measurements then tack welding together I ended up with all the base rails in place.

My chassis kit I received seems to be missing the front frame tubes but as mentioned earlier I have my other front frame, ( note the different coloured metal and white marker writing on the f/frame)

http://i181.photobucket.com/albums/x47/f70-ryp/e0d18fbd1f889f30f4b39f9223115ea8.jpg

At the end of play today I had all the base rails down, the front frame lined up and tacked and I'll start on the uprights tomorrow evening.

[CJ27]

http://i181.photobucket.com/albums/x47/f70-ryp/a84ac034c3c1148deb32d23a4b69b6b8.jpg

I'd be interested to know if others have fully welded there base rails before moving on to the uprights? The book says to tack it but I can't help think it would be better to fully weld, dress back and move onto the uprights?

All in all feeling fairly happy with myself today! :)

Thanks for reading.

[SeriesLandy]

Looking good, it's been a really long time since I built mine but I'm sure I tacked then fully welded later on.

[Dualist]

Welcome Chris, nice start :)
I tacked all my frame up first then started to full weld it to minimize any distortion. It was clamped/tacked to my bench then I started with all the down hand welds first so stopping any hope of the box section twisting.

[TalonMotorFabrication]

Weld all the base tubes together across the tops with each tube clamped in place,then weld each vertical joint. Tack the front frame in place using some spare tube to hold it in place,then ignore the book tack SB1+SB2+D7+8 in place and do a diagonal measurement between the corner of SB2 and the front frame (get this between 2-3mm and you'll be doing well). Tack the uprights in place then TR1+2 3+4 and 8.

[j.brownster79]

Welcome Chris good to see another mx5 build!! I tacked my chassis up first before I fully welded, weld opposite directions one weld at a time giving the frame to cool in between, more time you give the frame now less hassle you will have later on! I found this forum great help with plenty of free advice it's never a stupid question so just ask!

[CJ27]

Thanks guys!

It's funny you mention distortion as I noticed this, you'll see in my pictures that I improvised with a block of wood screwed down over the tube as I tacked them, it seemed to help a bit.

Phil thanks for the reply, I think I'll heed your advice and just weld the tops and some sides, then crack on as you've suggested. I've already got the front frame tacked in place.

I've checked all my measurements including the diagonals, they've all come back spot on so far, I know it's only the bottom rails but is good to know.

[CJ27]

Welcome Chris good to see another mx5 build!! I tacked my chassis up first before I fully welded, weld opposite directions one weld at a time giving the frame to cool in between, more time you give the frame now less hassle you will have later on! I found this forum great help with plenty of free advice it's never a stupid question so just ask!

Thanks for the advice, I think I'm going to weld the tops as said, moving around the frame to spread the heat and I'll give it plenty of time to cool in between.

They'll certainly be some stupid questions I'm sure :D it's all a learning curve at the end of the day!

Chris

[K4KEV]

welcome Chris....nice to see another build being born, if you get stuck you will always be able to find an answer within these "walls". I would advise getting a larger capacity gas bottle as you will find those you are using don't last 5 minutes ( that is almost literally ) try and get a pub bottle if you can.

[CJ27]

Thanks, the gas bottle was an emergency spare as my usual supply ran out when I was finishing my mini project, I just haven't got a refill yet.

[CJ27]

Evening all!

I managed a good few hours on the build tonight with some good progress (well I think so) :p

So I left yesterday with the base rails tacked down and the front frame aligned and tacked, today I moved on the seat rails, uprights and some top rails.

I started by tacking in the two rear seat rails SB1 and then U4 and U5.

http://i181.photobucket.com/albums/x47/f70-ryp/7240c56b371e6dc61007bb36aa7425d4.jpg
http://i181.photobucket.com/albums/x47/f70-ryp/a30517d448f1fdd6aa359466658beabb.jpg

I then got d8 roughly in place and then TR4 and D10.

All clamped in place and measurements checked
http://i181.photobucket.com/albums/x47/f70-ryp/914d454ee4d8ebe0ee5997ea9819019c.jpg

I checked, checked and checked the measurements and then tacked them in, I forgot to mention I put SB2 in place also.

[CJ27]

What I did find is that when placing D8 onto SB1/SB2, they didn't seem to fit fantastically, I can see why, so I fiddled around until I was happy enough with the portions and then tacked them in place.

First attempt with SB2 not sitting very well
http://i181.photobucket.com/albums/x47/f70-ryp/740c3a52bdda4a37ea63963e5c740af9.jpg

Second attempt, better, not fantastic but I was fairly happy with this and I tacked it in place, the gap at the top of D8 to SB2 looks bigger in the picture than it is.
http://i181.photobucket.com/albums/x47/f70-ryp/9151bbadb255032b8fe2bf51345880eb.jpg

I then moved over to the passenger side and did the same and then moved onto U6,8 where I had some issues placing them, I'm still not 100% on these and there just resting in place until I figure it out tomorrow. I did fit TR1 and TR2 and got them tacked onto the front frame.

http://i181.photobucket.com/albums/x47/f70-ryp/4E3739D0-5524-43FB-A6E6-84649F59367D.jpg

[CJ27]

I left it tonight pretty much at this stage and tomorrow I'll move onto finalising U6 and U3, U8, U7 and getting TR8 in place.

If anyone could shed any light on my question in the chassis section it would be appreciated.

A small note on my measurements, I've been checking before every tack my alignment of each tube and the overall chassis to check for distortion etc, I'm happy to report I'm + or - 1mm overall on all my sizes, I'll check every thing again before I fully weld.


A final picture before I turned the workshop light out

http://i181.photobucket.com/albums/x47/f70-ryp/DD999A2D-2E25-48E6-93BF-205E6A91E5AD.jpg

Night all.

[alga]

You're supposed to chamfer the bottom edge of the diagonal tubes D7, D8 where they interferes with the seat back rails, see their drawing on page 165.

[CJ27]

Ah, I missed that bit, thank you, that makes sense now, I'll sort that later.

[flyerncle]

Fairly critical as it affects the placing of roll bar and rear shock mounts and the rest of the rear end.
Dont ask me how I know :rolleyes:

[CJ27]

It's been a few weeks since I've managed any real progress on the chassis, a birthday trip to London and trying to complete some block paving at home have put pay to any real progress.

Fortunately I've managed a few hour this evening to carry on.

Having tacked most of the main chassis now I decided to move on to tacking up the diff cage area.

http://i181.photobucket.com/albums/x47/f70-ryp/31612bec89db67896354e3625d06607e.jpg

Main diff cage tacked up

http://i181.photobucket.com/albums/x47/f70-ryp/ab701194b64963b132303035ee55ea33.jpg

And attached to the chassis

http://i181.photobucket.com/albums/x47/f70-ryp/6fdfedf3b94702b4601e70d018850545.jpg

Once I'd got this tacked on I've now moved the chassis back to its original position on the build table and clamped it down in various places, I've began to check all my measurements and start to fully weld the top section of the chassis.

I've decided I'm going to tweet the front frame a bit, I'm not happy with the gap between the front frame and chassis tubes, I'll un tack and grind the welds down a bit and re line up and tack.

I've fully welded half of the top frame now,I need to fiddle with the welder a bit as the wire feed is playing up before I carry on.

Thanks for reading.