Lotus 23 project

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Cheers Stephen

Lotus 23 project

Postby bzrse7en » Sun Mar 13, 2011 1:28 pm

Thought I might as well start a build diary.
I cannot do too much until my 7 has sold, but some interesting discussion might eventuate.

I have bought the first parts and sent in design approval.
The LVVTA tech commitee meet on the first tuesday of the month, so have about three weeks to wait for any news for, or against my planned project. I believe mostly it is just a formality, aproval will be granted, maybe with a few detail changes.

Lotus%2023%20X%20copy.gif (250.24 KiB) Viewed 12665 times

Car is a Lotus 23, mid engined, originally with lotus twin cam, or 1000cc coventry climax. Was successful at LeMans in beating and lapping much larger hardware, but was disqualified. I believe because the front wheels were 4 stud, and the rear were 6 stud. I know it dosn't sound logical, but that's the frogs for you. Reminds me of Monte Carlo, minis were 1st, 2nd and third, and were disqualified on light bulbs - wrong brand or something.
The 23 is about the same size as a seven, originaly a bit lighter, and slightly lower. All enveloping bodywork in fibreglass, spaceframe chassis, a widened version of the lotus 22 F1 car.
Anyway, here are the specs of my planned build:
Space frame to original drawings, except 25x25x1.6 instead of lighter guages.
Nickel bronze welded.
Triumph front uprights
Custom rear uprights with sierra bearings and sierra half shafts with lobro CVs.
Ride height raised to frnt 100mm, rear 110mm without stuffing up susp geometry.
Brakes will be Capri vented discs and ford or aftermarket calipers, rear will be sierra discs and calipers.
Engine VAG 1.8T and transaxle, 200hp std. Easily 300hp with min mods.
Steering rack triumph hearld
Steering column, something short with british splines, so BMC Alegro or FWD ford. It needs to be short to get an angled shaft to the rack.
13" wheels, 7" front, 8" rear.
Spartan interior.
Barry Lietch L23 bodywork, unless someone has knowledge of moulds somewhere else.

I have purchased the Herald 13/60 uprights and a rack for $150. Was going to use the triumph brakes , until I realised how small they are compared to whats going on the rear. Larger Triumph GT6 / Vitesse solid discs fit as do M16 calipers fitted to Cortina. The Cortina discs can be modified to fit, as they have the same off-set, just different bolt pattern. Capri 2.8 have vented discs with same specs as cortina, so have decided to go this way and find suitable calipers that'll bolt on, such as Granada, Cortina, Austin Princess 4 pots, or if money not a prob, I'll go M16 outlaw 4 pots.

The Herald uprights use trunions, or can be modified easily for spherical bearings, I have decided to keep trunions, so the front looks accurate to original. Trunions are available from the UK and are not expensive. The trunion threads seem to be in excellent condition, although there is a bit of rust pitting above the thread as the stud transitions into the upright forging. Hopefully this'll polish out on the lathe. These uprights do impress me, they are so much lighter than the cortina ones, stub axles and arms unbolt, so can be changed and can be swung in a small lathe. The only thing that unimpresses me is the old fashoned felt grease seal, not a rubber lipped seal.
Just about every race car manufacturer used these uprights in F1 and F2 until 1970, so they cannot be too bad.

I am seeking approval on a smaller A arm tube than LVVTA recomends. They recomend 25x2erw, I am asking for 22x2 high strenght erw, it has a yeild strenght double mild steel.
Someone please buy my seven, so I can get started!
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Location: Rolleston Canterbury

Re: Lotus 23 project

Postby bzrse7en » Fri Mar 25, 2011 6:52 pm

Spent last weekend redrawing the brackets into CAD.
Just put in my laser cutting and the tube bending of the dash bulkhead at Autobend = $250
Ordered a sierra disc brake rear end = $250+gst, more than I wanted to spend, but as it turns out, it is actually a good price.
and bought a second set of Triumph uprights, rack and hubs off trademe = $100
Why did I buy a second set you may ask? - because they are Vitesse / GT6 units with larger brakes and stubs, they are rare and highly sort after, $100 is a good price, I paid $150 for the 13/60 stuff and thought that OK.
The vitesse discs are the same size as Cortina, where as the 13/60 are quite a bit smaller and thinner. I had planned to modify Cortina discs and calipers to fit onto the 13/60 hubs, now it isn't necessary.
Looks like there is no going back now.
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Joined: Thu Apr 23, 2009 3:40 pm
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Re: Lotus 23 project

Postby bzrse7en » Mon Apr 04, 2011 9:29 pm

No real progress, but something interesting-ish to report.
I have a workmate who is a bit tight with the $$, he was given an old rusty cast iron frypan and he bought it back to new condition with nothing more than baking soda and a battery charger.
With my sierra disc brakes being a bit weathered,I thought I might try it out. The beauty of this is that I was going to machine these rear discs and this process will remove the rust which takes the edge of lathe tools.
This is what I did:
Recycling wheely bin 1/2 full of water.
$3 of baking soda
Hung the discs and a few rusty brakets in the solution with welding wire.
Stick in a piece of stainless steel as an anode
Connect the bat charger - wire to parts and + wire to stainless steel
crank up the charger to max
walk away for a couple of hours.
There was bubbles aplenty and the water went black.
In the end I had to leave them in all afternoon to remove all the rust.
Out the discs came with all the rust removed - but replaced with quite a bit of pitting and a black finish all over - no rust thou, so good enough to machine.

I should have spent another $3 on more soda as I think the solution was a little week, and on reflection, media blasting would have been better as it gets rid of all the other goo associated with brakes, but it was cheaper, nicer and less labour intensive than using a wire wheel (none of those rusty coloured boggies either).

So there you go, nothing much going on, but possibly interesting-ish to someone.

I have also started on the 23's rear bulkhead, but that report can wait.
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Joined: Thu Apr 23, 2009 3:40 pm
Location: Rolleston Canterbury

Re: Lotus 23 project

Postby bzrse7en » Tue Apr 19, 2011 5:12 pm

Awsome, I have design approval!
Although paperwork hasn't turned up yet as they are snowed under, they have emailed the important queries:
Chassis and A arms all good.
They'll let me use 25 round and square x 1.2 wall ERW tube which surprises me, I thought 1.6 wall was a min on chassis, this'll save a bit of weight.
Nickel Bronze welding OK
All bulkheads are tacked up and starting to work on A arms.
Any photos so far prob won't mean anything to anyone until bulkheads are on the chassis jig, and that cannot happen until I have sold the Seven, freeing up space.
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Joined: Thu Apr 23, 2009 3:40 pm
Location: Rolleston Canterbury

Re: Lotus 23 project

Postby bzrse7en » Wed May 04, 2011 8:46 pm

This post is also published over in the tech area.
Pictured is my Triumph Herald Rack.
rack.jpg (244.57 KiB) Viewed 12318 times

I have calculated I need to shorten it by 6 1/2". This'll involve screw cutting a new thread further up the rack. roughly where indicated in vivid. I am a bit concerned by the flat machined into the rack, most likely there to vent air thru the bush when the rack is moved from side to side. Not sure if this'll compromise the thread's strength.
Rack diametre is 20.6mm and flat takes off 1.9mm - yea I know the rack was made to old school dimensions not these new fangled (and french) millimetres.

This rack is fairly common in Lotus replicas and will have been shortened many times.

Just found this on a forum, not sure about welding steering:
Originally Posted by gxxr
Spoke to a guy who used to mod the usual British based racks in days of yore for formula cars. Typically, he'd cut the rack in the appropriate spot, drill and tap for a 1/4" stud, V the join, screw together and weld and finally turn it to clean everything up. Some of these same racks are still getting round more than 40 years later.

When appropriate racks became available locally, they were not heat treated as far as he could recall. Cheetahs even had an aluminium rack, so unless you are doing parking manoevres, doubt you'll have a problem.
Last edited by bzrse7en on Thu May 05, 2011 5:01 pm, edited 1 time in total.
Posts: 1472
Joined: Thu Apr 23, 2009 3:40 pm
Location: Rolleston Canterbury

Re: Lotus 23 project

Postby bzrse7en » Wed May 04, 2011 9:03 pm

On the above subject of shortening racks. To remove bumpsteer, the rack needs some serious shortening.
If you look at the 23's front arms, you'll note the A arms pivot axis are not parallel with the car's centreline. I am not 100% sure what this theoreticaly will cause the car to do, but it does add some difficulty to working out the rack's length.
Generally on a normal set up, all you need to do is make sure the tie rods are parallel with the bottom arms from the front, and the inner tie rod ends intersect the line drawn between the top arm and bottom arm inner pivots - again looking from the front.

On the 23, bit of form 6-7 tech-drawing is required, namely Points, Lines and Planes using all three views of an Orthographic drawing. I'd post the drawing, but it is a bit of a mess, none the less it is interesing.
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Re: Lotus 23 project

Postby bzrse7en » Sun May 08, 2011 7:57 pm

This is more of a spleen vent than a progress report, it isn't progress, more regress.
Over 2 weekends I made the A arms front and back for the 23. I was very happy with the result, good tight joints, laser cut parts fitted well etc....
Steven had suggested I use his mate to TIG them and quoted $40 per A arm. I thought I would try a local company, a company who I have used before and who does hi-performance type welding (Not trailers etc..) I won't mention who it is as yet - not till I find out what they are going to do. They did my seven roll bar and MSNZ were happy with the welds, as I was.
I picked up the 6 arms friday 4.30, the workshop was quite dark so I didn't see most of the faults. Some of the welds looked pretty tidy, but I did note a bit of under cut and a couple of places missed. He happly did those 2 small bits before I paid and left. I paid $120 which was half the price of Steve's mate. He knew I would be back with 6 radius rods to be TIGed as soon as they were made.
I wire wheeled them this afternoon and the closer I looked, the worse it seemed.
Porosity in many places
Small gaps and pin holes
cold lap
wide weld beads indicating a balled electrode
Under cut and melted edges - probably because of the balled electrode.
variable feeds - some noticably rushed.
Infact it all looked rushed - except for a couple of welds I had looked at.
I found all of these things on every arm.

Obviously I'll be paying this bloke a visit monday.
The guy is a one man band, and I have seen some hi quality welding in his shop - it is almost like another bloke did it for him.
What sluts me off is that even if he gave me my money back, I am still 2 weekends down, a length of tube and several laser cut brackets short - and a bit pi$$ed.
It is also dejavue, as when I did my seven, the exact same thing happened, except the bloke was a mate and he pretty much fu%ked a set of arms front and back + rear uprights. The second set, I took to a place with a sign above the door.
I know my students whilst MIGing often realise something isn't right - like the gas is off, but they continue anyway. I naively thought someone with 4711 and does this for a living would know to stop.
I was quite prepared to recomend this bloke on this forum, after all, the price was right.

I will report back after monday.
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Re: Lotus 23 project

Postby bzrse7en » Sun May 15, 2011 5:33 pm

A arms.jpg
A arms.jpg (85.06 KiB) Viewed 12184 times

A arms and unwelded radius rods.
A arm welds are better but not without issues.

front bulkhead.jpg
front bulkhead.jpg (81.88 KiB) Viewed 12184 times

Front bulkhead in jig and mocked up shortened escort rack.
1 7/8" only needs to come off the escort rack, where as 6" would need to be taken off Herald. The herald rack is supposed to be the right one.
Also the Herald rack needed to be off-set as per original drawings, as the pinion position is defined by the pedals, not by the rack's position centrally in the car. This means, basicly a mess, either the pinion dosn't sit in the middle of the rack's gear teeth, or an extension will need adding to the R/H end of the rack. The escort rack is a bit different and the pinion angles up more steeply, giving more pedal clearance, so the escort rack can (hopefully) be mounted centrally. With pendulum mounted pedals (in stead of floor mounted), this should give the desired space.

Dash Hoop.jpg
Dash Hoop.jpg (70.09 KiB) Viewed 12171 times

Dash or "Terry Hoop" will have sheet steel welded onto this front and back with lots of holes, some holes for instruments. Note lump above steering wheel hole, this is for tach. Original 23's had a centrally mounted tach and no speedo, some people have a Speedo pod near their right arm, but this seems a bit micky mouse, I will have speedo and tach side by side, so will be deviating from original design here.
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Joined: Thu Apr 23, 2009 3:40 pm
Location: Rolleston Canterbury

Re: Lotus 23 project

Postby bzrse7en » Sun May 15, 2011 7:48 pm

If you have kept up with this thread, you'd know I had issues with the (prefered) Herald rack. To shorten it, I would have needed to build up a flat area with weld, LVVTA said NO to any welding. It is ironic what I found under the Escort rack's boot - some people are soo rough!
Rack end2.jpg
Rack end2.jpg (89.09 KiB) Viewed 12165 times

Seatback bulkhead pictured. Square hole in botton centreis for the gear linkage and fuel lines to run thru.
Seatback bulkhead.jpg
Seatback bulkhead.jpg (64.5 KiB) Viewed 12165 times

Rear bulkhead
Bolt-in top crossmember is temporary.
Rear of Transaxle will (hopefully) pass thru this frame.
Rear Bulkhead.jpg
Rear Bulkhead.jpg (66.19 KiB) Viewed 12165 times
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Re: Lotus 23 project

Postby bzrse7en » Wed May 18, 2011 9:24 pm

Shortened the rack yesterday. 1 7/8" removed and a new thread screw cut on the end. I quite enjoy the satisfaction of screwcutting, but it does make me nervous - A bit of slack in the machine and a heavy cut and it's all over. Thankfully it went well, I cut a practice thread in ally first and that seemed to work, the screw cutting and set up took about an hour or so. The thread is a 20 TPI and some real odd-ball imperial diameter.
20 TPI.jpg
20 TPI.jpg (120.69 KiB) Viewed 12113 times

Also shortened the outer housing by 1 7/8". I used a piece of line pipe, bored out the inside for a good firm fit over the rack tube, checked for run out on the lathe, there wasn't any due to the good tight fit of the sleeve. I then Nickel Bronzed the housing back together.
A new plastic bush from Raycroft also aquired.
shortened rack.jpg
shortened rack.jpg (178.47 KiB) Viewed 12113 times

I need to make new lock nuts for the rack inner balls, then I plan to reassemble in the weekend.
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