First thank for your big statement – lot of questions…here we go:
My car is a A 110, not a A 310. The car is more fragile looking, much lighter and has a 4 inline engine from Renault 5 Alpine. Basically 1,4 L / 93 hp, my engine is in progress , bored/stroked to almost 1,8 L, estimated 200 hp with all steal internals, big head /valves , ITBs and all the stuff as you know supposedly.
My gearbox ist the 330 4 speed, can be converted to 353/ 5 speed, but the stock ratios are too short and the steps are poor, as well the gears and the diff too weak. In Germany/France usually this typ of boxes will be upgraded with the internals of the NG5-gearbox from R5Alpine. The gears and diff is much stronger, but the ratios are even worse as the stock box. The ratios are 3,81/ 2,17/1,41/1,03/0,86, final drive 3,77. My layout is 2,63 / 1,68 / 1,28 and 3+4 can accepted with 1,03 /0,86. Of course, I need only the internals such as in/output shaft, gearwheels, hubs, dog rings etc., I can use the stock gear housing and maybe the forks and selectors, maybe that they have to be replaced to stronger ones. Further, I would
keep the main shaft with the pinion and crown wheel which is strong enough.
My engine with a spec.output of 113 hp/L will pull strong just over 4000 rpm, and I need close ratios and a long first gear what I can use as a really drive gear. I intend to use my car mainly as a trackdays / slalom car, just for pleasure, no daily driver. But I don´t do any serious competitions. For me it´s also important to be able to go on a German Autobahn ( freeway) with 100 miles without getting mad due to excessive rpms. The target is 3000 rpm and 100 km/h (62 mph) in 5. gear. Currently, in 4. ( last) gear the stock gear of my car makes 70 km/h with 3000 rpm, you are going to go crazy when cruising.
Due to the relationship between car layout and power, it´s impossible to make max speed with this car and 200 hp, because it would be theoretically be appr. 280 km/h ( 175 mph). With this speed, the car would take off like a plane. The power can only used for accelerating, max. speed maybe 220 with really big balls.
Your 3. question:
I´m an engineer, but no designer. My profession is engine development, and I was in the past involved in German DTM and later as well in even much higher revving engines with 10 cyl.
I`m no gearbox specialist, but due to my experiences I trust myself to make a working layout. I know how dog boxes are working. I have some possibilities to machine parts, but not good enough to produce those internals for a dog box. To make this professionell, you need CAD/CAM design tools and a CNC turning machine, CNC milling and compagnies with special toothing machines. A friend of mine who is designer did my constructions together with me , unfortunatly he´s got seriously sick some weeks ago and I don´t know if he gets ok again at all.
Basically, it´s absolutly necessary to source a compagny which is prepared and interested to make the parts. I`ve had some contacts here in Germany and I first intended to pre-turn all shafts and wheels by myself and let the toothing procedures and the case hardening make by order of the particular shop, but in Germany, we have very high labor costs and the charge just for all toothing work and grinding would be around 4000 €, and yet I would have to bring the turning parts too.
So I have looked around and I found a shop in east Europe where the labor costs are just a fracture of the germans and the quality is top level, some german race shops let their work do there. I had some contacts to them via Email and they invited me to talk about my plans, but as told, I have no drawings or CAD models currently available.
Your concerns about the load of the dogs are not as critical as you are worried about. Every motorbike has a dog box and they are working some 10000 km without troubles. Of course I admit that the loads of a bike are notably lower due to smaller torque and less weight oft he vehicle. But the loads on the dogs doesn´t cause breaking out of the dogs if the are dimensionally correct designed and hardened. The bigger risk is inappropriate gearchanges by people without dog box practice. Then the edges oft he dogs are crumbling, especially if they are poor designed and hardened. If you do firm, quick gearchanges, a dogbox can live many years.
Your intension with the splined dog toothing at the gearwheels was as well my consideration to avoid the changing oft he gearwheel itself if the toothing is worn. But honestly: The manufacturing of such an assembling with gearwheel and toothing, add spline tooting on the gearwheel itself, add inner spline toothing on the shift dog, add flat grinding of the gearwheel and the shift dog…..in summary you have much more effort and costs as to change just the integral gearwheel. Furthermore, you can save space to make the gearwheel wider – and definitly less costs. The toothing of a gearwheel is very expensive if you make one unique part – if you make more, they are almost free. My toothing specialist adviced me to find some other guys to make 3 or 4 part sets, they would be a fracture of costs. If one gearwheel is 350 €, I would get another 5 ones for 30 € each !!! So you can make the spare parts straightaway together with the inital order. The big costs are set-up costs.
To use inner parts of another gearbox mostly fails due tot he different shaft distance. On my gearbox is it 70 mm. You proposed as well to use approved parts of reputed suppliers such as Quaife, Sadev, X-Trac a.s.o. None of them have suitable parts for me, and if they would fit, they even are offering only straight cut gears which are noisy for public traffic what I wouldn´t accept at all.