[attachment=4912 Wrote:Paul N-M pid='21143' dateline='1545900089']
(26-12-2018, 09:34 PM)Dennis Nicholas Wrote: I have fitted a big 7 front axle on my Nippy chassis. I need to put weights on the front of the chassis to load the front spring to normal running position so I can check where the radius arm mount will come so that I can fix it to the cross member then measure the castor using 5/8" rods through the king pin eyes. This will be to see if a wedge is needed between spring and chassis.
Does anyone know what the weight of a big 7 engine and gearbox is? I will probably use sacks of coal on planks as the main weight to start with.
The actual engine being used is a BMC A+ with Toyota T50 5 speed box.
OK you are going to ask why not just mount the A+ engine and take it from there? Yup I think that is what I must do then add a bit of weight for the body/rad etc.
There that is age for you, talk to yourself and the answer eventually pops up.
Dennis
Hi Dennis,
I built a racing special using a Big Seven front axle and a 1956 Austin 948 A series engine/gear box. Goes rather well but there are many mods to the chassis/brakes/steering/dampers to achieve this. The engine weight depends on what you are keeping. My engine weighs arround 170lbs but has no generator, has a very lightweight starter and an aluminium rear block/gearbox plate as well as a very light flywheel. the heavy cast iron inlet/exhaust manifold has been replaced with tubular headers and aluminium. The box weighs 45lbs.
Some others have put A Series engines in A7 chassis, of course Ford 1172's were popular. I think there was a thread on this forum some time ago re this. The main problem with fitting an A Series is the existing cross member. I have seen engines sitting way too high to avoid it as there is little room to place the sump between the chassis rails unless you move the engine back which has knock on implications one of which is the location of the tourque arms.
You have obviously decided originality is not important to you but doing this conversion to an existing car IMO needs to be carefully considdered. What is your objective? There may be alternatives depending on the outcome you are looking for.
I did all of this on a scrap chassis as a bit of an engineering exescise so could design in all the mods required to build a sprint/hill climb car for local events so wasnt 'harming' an original car.
Paul
Hi Paul. No fear of ruining an original Nippy. It came to me around about 1969/70 as a pile of Nippy bits including one that was being rebuilt (by an aircraft apprentice), a spare body and this one which had been "rebuilt" but soon after crashed into. It seemed a waste to me to just use bits from it. I had a seagoing career and needed a good fun car with a bit of go to take me and two large suitcases to ships in refit (mostly Devon to the Tyne). I have tried to keep as much original as possible. It already had hydraulic brakes all round. The body floor around the gearbox area was already badly cut about including the bit that caries the car number being missing.
The crash damage was quite severe including bent chassis members, spring came out of chassis mount and bent upwards 90 deg. then further 90 deg. back to axle which was also slightly banana shaped but shafts turned out to be ok. The boot was well squashed in at the back with woodwork broken. I removed the division between spare wheel area and boot..hey presto large suitcase will fit; and with passenger seat removed second large suitcase fits. I made up a chassis extension to go back under to support the whole boot area. I use a BMC A engine and gearbox (A35). front mounts....A series bolted to flat 1/8 inch plate suitably bent and bolted to cow-horns. A replacement chassis was donated to me and the slight modifications made to cross pieces to make it Nippy shape. The much crinkly longitudinal chassis member from the crashed chassis was beaten about a bit with a hammer until it just fitted about 6 inches apart from the standard one. The BMC gearbox mount a bit cut down sits on top of and is bolted to these two longitudinal members....simple. Working with my local garage we found that the A7 prop shaft was a good push fit over the stump of the BMC gearbox U/J once the BMC hollow shaft had been turned off at its weld so just needed welding to the stump after shortening.
Instead of wood frame at the back I have used 1/2 inch angle cut at intervals, bent and welded back together; also angle from that tied down to the chassis boot extension....so no more door frame pillars breaking. The spare wheel carrier is mounted on the outside of the boot lid with cross bracing inside. I did have access to gas welding and self taught myself the basics.
The car was used as a daily when I was home and I used it in MCC trials with quite a bit of success. Eventually the body was rather falling to bits and the 948 engine broke a top ring on one piston......time for a rebuild......that was a good few years ago and an interest in Reliant Scimitars.....good comfortable fast cars......has taken up some of my time. At the time of rebuild start the BMC A gearboxes were becoming scarce so a look around revealed a firm doing a conversion (For Morris Minors) for a Ford type 9 gearbox to fit the A series.....but but but...on offering it up the oil-way protrusion fouled the front chassis cross member. (rude words here). Further looking around found another firm offering a Toyota T50 5 speed box kit. That did involve removing the A series box tunnel, cutting the floor back a little further and fabricating a new one for the T50.....with still enough room for feet on both sides. After abortive attempts to fabricate a mechanical clutch I opted for a hydraulic.....that and the positioning of the Mini brake cylinders on the body outside and above the pedals has allowed a floor with only one hole for the steering column which will have insulating filling.......so no more freezing feet and cold air blowing up. A two speed fan heater just fits nicely above the gearbox tunnel......just right for the further development of this fast little tourer. A BMC A+ 1275, 40,000 mile from a crashed car became available at the time of the rebuild start so that was snapped up and only slight modifications required for Toyota gearbox mount. The crankshaft even turned out to be the good one with the correct fillet radius ground at each big end. The sump has had a concave cut out bit welded in on the nearside to allow the engine to be lower in the chassis.
Another modification was the dashboard so that a rev counter could be fitted. It is a replica of a Nippy one but just a bit longer. To those that do not know the cars it looks original.
So there it is- a car that was destined to disappear now still around. And with the 5 speed box and 15 inch wheels should provide unstressed fast touring.
Unfortunately the T50 gearbox has now become extremely rare and I have just had to pay a silly amount for one as a spare, but hopefully it will last a very long time being the same one that was fitted to Toyota larger engines.
The engine will be standard with a slightly better low down torque cam (though as I will not be doing any more trials this is a bit superfluous!). I have a Weber carb and manifold and will have a stainless exhaust made up.
The Big 7 axle was fitted and in use some time ago but without much regard to really correct fitting and I am wondering if the spring/shackles were twisted.......I am about to see.....which is the stage I am at now.
Just had a hip replacement and now on waiting list for the second to be done so there will be more delays in the garage work.
I have a comprehensive photo record of work so far if you wished to see any stages.
The steering is otherwise standard.....have you used Rose joints on your steering link, box to front steering arm? I did partly follow earlier discussions on the subject and am wondering if it is worth doing, purely from ease of renewing items.
Dennis
