RWD, XE, MG Midget

[Aubrey_Boy]

Having spent so much time and money on my Mini project it is clear that it is going to cost at least 10 - 12k and with the best will in the world is going to be another 12 - 18 months unless I spend quite a bit more money on out sourcing work.

So in the interests of having something to drive relatively quickly I looked at buying something RWD which was either ready to go or didn't require too much work. And something else to work on when I am sick of looking at the Mini

My criteria:

RWD (Front engined)
Not a kit car / locost (Just preference)
£3000 total project cost
As fast as possible within the budget
Readily available (I don't want to spend my life looking for one)
Preferably old / 'classic'
Prefer fixed head not convertible

Which quickly results in:

MX5 - Most likely a 1.6 to be in budget, good handling but slow-ish

200SX - Pretty quick but most examples I looked at in budget were pretty tired, needing new suspension bushes / dampers / brakes and no shortage of blue smoke and the likelihood of some pretty scary rebuild costs any time soon.

So I ended up buying the slowest RWD car on the planet - 1275cc MG midget

I decided I couldn't buy what I wanted so I needed a front engined RWD base car which was as light and as cheap as possible.

MK1 / MK2 Escorts - out of my price range
Triumph GT6 - Heavy, rear suspension!, relatively rare
MG Midget - cheap, light, slow, lots around, cheap structural repair panels.
MGB - As per Midget just more expensive and heavier

TBH I probably should have just bought the MX5 as an instant RWD solution but hey...

The victim the day I bought it:



Sort of a cross between snot and diarrhoea as colours go, but that will change. Full MOT / Tax and I drove it home - slowly, very slowly. It wandered all over the place and felt like it was doing 6000 rpm at 70 mph in top, the steering wheel stayed where you left it, but the engine felt fine (as far as an engine with little power goes) and had good oil pressure.

It is absolutely tiny - which I really like, believe it or not the wheelbase is 4mm shorter than the Mini. It is far from being manly like a slammed / arched Tarmac spec MK2 Escort but I really like it and its simplicity, no I'm not gay or owt!

So the plan is 170 bhp / 750 kg = 225 bhp / metric tonne but hoping to come in less than 750 kg. Hardly ground breaking but more than enough to test my lack of driving talent.

[Graham]

sound great

[Retromotorsport]

Arch it ....

[PaulAlex]

Throw away that softop and fabricate a unique roof

[mgbgt]

Good luck! This will be interesting.

[AOK]

I like that a lot

[rallyladgaz]

this could be good keep us posted

[e321]

I had one just like it nearly 30 years ago, put a ford crossflow in it , found the g/box tunnel quite small and not a lot of room to enlarge it, and i do quite fancy another.

[Aubrey_Boy]

Cheers guys, thanks for the comments.

Retro,

My plan is to keep it standard externally, except maybe for removing the bumpers (to save some weight).

I have seen very few arched Midgets that look any good but it may become necessary depending what I decide to do with the back axle as the std Midget one is going to expire pretty quickly. If I used a Ford live axle (English?) then arches would be required to avoid having to narrow the axle which would become too expensive.

PaulAlex,

Yes I know what you mean about a hardtop but again it would be too expensive within the project outline, I will have to buy a second hand standard 'works' hardtop as I have no plans to drive with the hood down.

Like this:



However if this were a "money no object" project then this would be the plan:

A Sebring Sprite rear end: These are £720 + vat (glass fibre) including screens



Another fastback hardtop:



But the plan is very definitely cheap and cheerful and use as many off the shelf parts as possible whilst keeping it cheap, so no bespoke fabricated parts etc..., the exterior will be 'ratty' as a respray will be too much

This was the 70 odd hp std A series engine



Tuning these engines is just no longer economic in my opinion, I did it 20 years ago, 1380cc, 45DCOE, LCB, Rimflo valves, belt drive, etc... £2000 for 110 fwbhp

e321,

Yes I am finding the same with the type 9 - it is very snug in the standard tunnel, which is going to require a bit of massaging to give some clearance, which is what I was doing today.

Cheers

[Dan]

i do like Sprites, probably the only MG i wouldnt mind owning... maybe an MGB but it would have to have the handling and engine sorted

theres one on pistonheads at the moment which has arches, escort bubbles on the front and custom rears. im well tempted by it as i think it looks spot on. running an XE too

[Harry Snotter]

cracking wee cars their,great project

[Aubrey_Boy]

Cheers guys,

Steeley Dan,

Cheers yes I had seen that one in the back of PPC

So going back to the start of the project the first thing I planned on tackling was the front suspension and steering to try and understand where the friction was coming from which was causing the steering wheel to stay wherever it was left.

The RF corner:



From an engineering design point of view the front suspension is my least favourite aspect of the car, you can see the single top suspension link is the lever arm damper itself and the kingpin has to be shimmed to control the vertical free play. But other than an overhaul there is no budget to think about a front suspension re-design / change.

So this is the suspension removed, after hours of dealing with seized bushes / bolts.



As you can see I couldn't resist starting to scrape off the underseal which looked newly applied which usually means it is hiding something nasty before being sold.

Which basically revealed a crappy patch which had been brazed on with a catapult:



The rust behind the patch (which hadn't been cut out ) was quite localised but I prefer to cut out a bigger area so it looks a bit less of a patch and more 'integrated'. Looks like I hacked it out with an axe.



Tidied up a little with the return from the floorpan recreated:



One of the good things with a Spridget is the fact that a lot of the inner panels are completely flat and feature less which means repairs can be done very cheaply (One of the reasons for choosing it)



Welded in place, seam welded along the top and plug / spot welded along the bottom:



Seam sealed and stone chipped (The car is outside so I need to seal each repair as I do them):



So as usual, I started on one thing and ended up doing something else

Cheers

[Aubrey_Boy]

I couldn't fail to notice all was not well with the sills whilst I was repairing the RF inner arch.



Where the front corner meets the inner arch is a mix of filler and glass fibre.

But when I bought it I knew the sills would almost certainly need replacing as it was clear it had had oversills:



The sill should be flush with the wings

Bodge cut out:



But it looks pretty terminal underneath after peeling the oversill back:





The over sill was tack brazed in a few places so offered little structural benefit

The full extent of the outer sill underneath the oversill:



But an hour or so later the outersills are removed giving a view of the inner sill





The front section removed:



Repair section cut and slotted with a fly press:



Repair section in place:



Last bits of the inner sill / footwell repair



Cheers

[racerboy84]

Sounds good project!

[Sonus]

Looking forward to seeing this progress.

[Aubrey_Boy]

Thanks again for the comments,

So back to the original reason for the strip down

New front lower wishbones from Peter May Engineering, these include new fulcrum pins:



The spring pans (these bolt to the lower wishbones and form the lower mount for the road springs)



These have been shot blasted and zinc plated.

The front calipers have been rebuilt at the same time (even though they will more than likely be upgraded)



These have also been shot blasted, zinc passivated, new pistons, seals etc...

The rebuilt front hub / kingpin assemblies:





New bushes (Std), inner wishbone mounting pins etc...



Cheers

[turbo m]

Looking good like you ideas.

[Aubrey_Boy]

Cheers Turbo M, thanks for the positive comments,

Guys, just a quick question / request for info:

As part of this project I am looking into the pros and cons of changing the rear axle to an English axle

Firstly I would like to know the width (drum to drum) of the axle?

Was the 100E, 105E and the Escort MK1/2 the same rear axle, i.e. all English or were these different axles?

Any info gratefully appreciated

Cheers

[e321]

100e is different, anglia and escort is similiar but escort is wider, would think the anglia 105e would suit the best.

[Aubrey_Boy]

e321,

Cheers, having searched the archives I feel an Atlas will be a better bet but it's probably too expensive for this project anyway.

Either an English or an Atlas would need to be narrowed and I think that just is not possible to do economically?

I want to keep it a live axle as it will be just bolt on (In theory), IRS is too much work and after some weighing of components for the Mini project it has surprised me how heavy the MX5 based IRS will be. Live axle Mini!

Anyway, still working on the front end:

Shot blasted and painted some more bits, bumper mounts, ARB bits etc...



FARB, number plate holder:



Expansion tank:



Rebuilt the steering rack: New track rods, gaiters, reshimmed.





The rack was very stiff so I needed to polish the rack bar which has helped a lot.

Reconditioning the bumper mounts was a waste of time as I have decided to remove them as part of a weight saving exercise which with other changes saves about 25 kg without spending too much.

Also I have saved about 6kg from the base engine for both projects, the ITB's, Inlet manifold, fuel rail, injectors and linkages all weigh less the 3.5 kg total.

This is getting close to meaning the overall weight will be similar to the std car, but still a bit to go yet.

I have modified both the clutch and brake pedals so that I can move the pedal box another 10 mm away from as the leg room is a little tight. (Before = top, Bottom = after)



Basically I have removed material from the back of the pedal and added it to the 'front' and moved the pad a little further away.

Cheers

[Aubrey_Boy]

Not a lot of progress but I finally purchased an ECU for this and my Mini project and will finish the loom design in the next week or so.

I know many will think it is overkill for this car and my other project but when you count the cost of all the additional units I will need and the requirement for a chassis data logger then it absolutely costs no more than the other options I researched.

My main driving force is the need for a chassis data logger.

When I purchased my Pectel T6 I did so due to a friend being a professional Pectel mapper on many high level Motorsport projects, when I started to look for this new ECU I had ruled Pectel out on the grounds of cost / necessity.

I wanted the following:

Traction Control - Slip based strategy (not RPM ROA)
Launch Control
WB lambda input
EGT (x2) K type
Knock control
ALS Control
WG control
Built in memory for data logging (Not PC logging)
8 - 9 Analogue channels for engine related monitoring / control
4 - 6 Analogue channels for chassis monitoring
4 Wheelspeed inputs
PWM for N2O control
PWM for Fuel control (N2O use)
PWM for fan control
4 cyl sequential injection
4 cyl individual ign coils

So to cut a long story short heres what I went and collected today from Cambridge:

WB Lambda input
Traction Control (Upgrade)
Launch Control
Knock control / input
3 MB data logging memory (upgrade from std 1MB)
Using the facility which allows me to use many unused channels as analogue channels I have no less than 24 analogue channels


Pectel SQ6

I no longer have my T6 which helped my purchase of this unit and all in all it cost a similar amount to the Autronic SM4 (Which was my main considered alternative) plus all the other external units I would have needed to get this level of functionality, plus I intend to use it on any future projects.

Cheers

[Aubrey_Boy]

Sorry Sonus not too much to report, but so far:

As I mentioned in my Mini thread I have been making wiring looms for both cars. I have been mocking the part finished looms in the Midget to double check all lengths before I fit all of the connectors to it.



I have also been getting hoses made for the fuel rail / fuel reg and feeds. The hoses will all go through the bulkhead using bulkhead fittings.



The hoses are braided but have a heat resistant sleeve fitted to try and reduce fuel temp a little.



You can just about make out the engine loom below the throttle bodies, I am trying to keep as much of the wiring out of sight as possible.

I have had to cut a fair chunk of the transmission tunnel away as attempts to 'porta-power' it wider didn't give enough clearance.

Also been researching rear axles for this, spoke to Fostek about a narrowed Atlas but it ends up quite pricey quite quickly and I don't want to make the same IRS as for the Mini so not sure what I will do yet other than I will not be using the std axle.

Whilst on electrics I have bought a master switch for this car, it is an ETA switch (they are industrial) originally intended to be used in rack mount panels.



I have modified the ends to take battery cable sized fittings. The good thing about these switches is they can be switched remotely by another electrical 'kill' switch mounted on the bulkhead for competition use. I have also noticed Demon Tweeks have started selling them.

Cheers

[mk2don]

nice looking motor that mate i did one a few years ago with a crossflow and it went well but not realy good handling but with spax on the rear and some wide rubber we got it so we could have a bit of fun in it but at 90mph it felt like a million mile an hour but good fun
the only real trouble is the space for the gearbox and we had to use a mk1 escort 4 speed box ,

heres a couple off pic's , looks like the one in the above pic next to the green midge



[img]http://med

[mk2don]

whoooops wrong picture

[Aubrey_Boy]

Further progress on the ECU loom, I have tried it in the Midget to see how it fits, the hope is the same loom can be made for both the Mini and the Midget but these mock ups will decide:

The ECU will be below the drivers seat to keep the weight low down and make it easily accessible as I will remove it when the car is not in use or parked up.



This shows the various loom transitions going up into the bulkhead, I have put the loom back in to establish the lengths for these various legs such as comms interface, PJB interface, Engine data loom, Engine power loom and engine grounds.

You can see the two bulkhead connectors in place in the upper bulkhead.



This where the bulkhead connectors come into the engine bay:



Here you can see the connectors for the TPS, Fuel pressure and Fuel temp



And because I should be able to power it all up in the next week or so I have made a download / comms lead to connect to the ECU, primarily it uses Ethernet for comms but will also have RS232 and CAN.



Cheers

[ENOFORD105E]

In relation to the axle why not look at what a Mallock uses. I'm sure its a midget casing modified to run an english Ford diff with quaiffe halfshafts....maybe on of the racers on here could confirm

[Aubrey_Boy]

A quick trial fit of the PJB panel to see if it is suitable for the MG.

Just the PJB panel:



Just laying it on the std dash shell:



The fact is that I don't need any ancillary gauges with PI Omega dash so even if I do try to integrate the old dash I'm not sure what I'll do with all the original gauge holes.

I think I prefer just the carbon panel but that pretty well dictates having no interior as it would look a bit strange having an interior and having the front bulkhead visible.

Pretty well all of the wiring is done now in the MG forward of the bulkhead, I've just added the main front chassis loom which is separate from the engine loom:





It all still needs tidying up and properly ty-wrapping down but there's no point at this stage as soon as the wiring is complete I will take the engine out and prep the engine bay and finish the engine and gearbox mounts.

Cheers

[Aubrey_Boy]

Having a break from the wiring looms.

The decision on the back axle has been made, its a 105E saloon axle with a 3.89 CWP, leaving it standard width for now as it's not too much wider than the standard axle, spring brackets etc already removed:



I'll get it painted / coated once all the brackets are sorted out

Drive flange OD turned down to 135mm:



240mm Escort discs chosen due to the amount of inset these discs give which will hopefully minimise the chances of wheel clearance issues. This photo shows the further track width increase that fitting discs gives, normally the standard drum is the same height as the centre location spigot:



One thing I hadn't anticipated was the centre location spigot being a proper fit on the inner diameter of the disc which means the disc is properly located / centred rather than relying on the studs for location which is a bonus.

All mocked up and caliper clears both radially and laterally



Haven't decided whether to fit the caliper fore or aft yet, I'll just choose whichever gives the best handbrake cable routing

I also plan to reduce the OD of the disc down as the caliper can come in 5mm or so which will reduce the effective disc radius and save a bit of weight as well as give more room radially





Should be in a position to mock up the caliper mounting brackets soon and look at the leaf spring mounts

Cheers

[Graham]

great stuff keep it up

[Dan]

nice work. that wiring loom looks really smart. coming along nicely

[raymondmarble]

You deserve to be knighted for that loom! You dont do homers do you?

[Aubrey_Boy]

Thank you for kind coments,

I have to be completely honest and say that my original plans were to just substitute the Anlglia axle and be done with it, owing to recent posts I have had to consider that lowering the rear roll centre will be beneficial at the same time.

The body mounted Watts linkage that Gary (Retro) uses is of interest but I am also looking at a similar 'A' frame system which doesn't need the Watts linkage and saves weight but also gives the advantage of a lower rear roll centre.

I can't emphasize enough that lowering the rear roll centre of a live axle is a very useful and desirable!

The two aspects I need to further consider are:

Roll steer

Anti dive / squat behaviour

I plan to look at kinematic models and post them if they are of any interest, I confess to being a bit of a suspension geek so I apologize in advance, I know that a Watts linkage is close to a straight line behaviour but not quite, I just need to understand what effects it

Cheers

[gringo!!]

wow!! you dont mess about do ya... i really like this project, and will be watchin with interest... keep up the amazing work...

[Retromotorsport]

As you say, its close to a straight line.. and it is, along most of the travel, its only at the extremes of movement that your get the slight curve of the end plots. And its effects are minimal..
Re the squat, as long as the forward links can point at the C of G you can have full anti-squat, but, you'll also want to take that out, dropping the lower link down to neutral otherwise you'll never turn the car in.
An option.. screw adjustable front lover links either side of the prop.. pull up at the lights, wind the links up, and launch ... leaving the other car scrabbling for grip, just make sure you wind them down before powering out of a corner

The roll steer, both upper and lower links pointing down at teh front, will give you some usefull toe in roll, level links zero steer. upwards facing.. oversteer

[Aubrey_Boy]

Cheers Gary,

Yes as far as roll steer goes I definitely want to be able to adjust so that I can get Toe-in in roll, getting away from the toe-out in roll that a standard leaf spring with the shackle placed at the rear gives.

Looking at the photos of your LRC Watts link do you use a poly bush for the pivot? It looks that way on Montys car? If it is any reason why compared to a bearing?

What length have you used for the Watts inner pivot rod end to rod end centres, I have started to look at lengths between 70 and 110mm to see what effect this has on the straight line behavior, either worse or better.

I prefer to use as little 'anti' geometry as possible as it can tend to feel unnatural and less progressive at the limit, so I will make the forward link pickup points with height adjustment to give some but not full anti squat / lift (i.e. pointing at the CofG.) And use as little as possible so the car doesn't move around too much.

The other challenge with this car is the longitudinal links are quite short, the lower link will be about 450mm and the upper will be shorter (400mm ish), I understand that the Works Escorts started with a short link setup but the longer link setup was better - which makes sense as the change of anti squat / lift with ride height is reduced with longer links making the behavior more consistent.

Cheers Gringo, just spending too much time at work at the moment, but not complaining as we all know how quickly that can change

Cheers

[Retromotorsport]

Mine are 100mm on centers , and the bush is for road use, the old nail NVH
I fitted a bush into a press and loaded it up with 1.5 ton, the movement was small enough that a dial gauge would be needed to take an acurate measurement... so i didnt bother.

Depending on how long your link bars are on the Watts, i think from memory these had more of an effect on the plot course than the pivot ..... but it was at the extremes of the travel.
You can get some extra length in your forward 4 links by placing then at the rear of the axle instead of center line ... that said the biggest problem i've plotted with short links is the fore and aft movement of the axle , the squat can still be adjusted with very short links .. of course in an ideal world we would have the links mounted in line with the C of G , shame theres a drivers spine in the way, allthough i've seen some 3 links that the center top link meets the chassis at the C of G vertical line. These running down the trans tunnels and being two bars mounted solidily to the top and bottom of the diff casing and meeting at a rod end, with triangular bracing all along its length, effectivly making a very long torque arm. I've never looked at these in roll, or RC height as i draw everthing long hand on paper.. then start plotting,
But that said theres some very effective american drag cars using short links and managing to lift both ends of the car on launch, allthough they have a wider spacing between top and bottom arms ... again, something which i havnt drawn out as i can get enough A/S with my current set up, the top of my body brackets are a bit higher than a standard Gp4 Escorts though

[Retromotorsport]

With regard to how much A/S you dial in, i would aim for full , but allow for zero, that way you have the best of all worlds.. Allthough its excellent for drag racing its also handy for moving the chassis from oversteer to understeer.
If you have a driver thats a point and squirt driver, on a short twisty course, give it loads of A/S .. let him charge up to a corner, lift the axle of the ground with braking, turn slow and then launch down the next piece .. if you cant change the driver, change the chassis
Long circuit, smooth flowing driver... lower the ammount of A/S to give him a car thats neutral to a tadge understeery... and allow him to feed the car from turn to turn.

If you tight for space at the front, make the axle brackets adjustable too. if you have room there, 3 holes above, 4/5/6 below could be possible? and will allow quite a lot of angle adjustment.

[Aubrey_Boy]

Cheers Gary,

Started to put together the kinematic model that I will use to look at the 4 / 5 link arrangement with Low RC Watts link.



Not quite ready yet as I still have to create the rear coilovers and the Low RC Watts



Rear discs are being turned down to 225mm OD (from 240mm) which has saved 0.4kg per disc as well.

Finishing the PJB this weekend, will post some pictures when finally done

Cheers

[Aubrey_Boy]

Got the discs back from the machine shop, they look really odd as the OD is so little and the disk ID surface being so relatively large.

I had to try the caliper / pad on the disc just to make sure 225mm wasn't too small:



I think 225mm was the smallest I could have got away with as there is just enough clearance.



I chose these calipers because they have the shallowest / widest pad shape I could find which allowed me to reduce the OD this way. Also they are lighter than the Sierra rear caliper from the published figures I have seen.

The effective radius is now 8mm less and the discs weighed just over 0.4kg each lighter as hoped.

I've weighed all the 105e axle parts and the discs / calipers / pads (dry) with an open diff and it comes to 43kg which is what I think the MG axle will weigh (not weighed it yet), I still have to add the brackets to the axle yet though.

Finished the kinematic model now



I just need to get on with using it so that I can find the roll centre height and the various lengths for the links and the pick up points



Cheers

[Retromotorsport]

I'll still stick with my string computer ..