A change of ratios
Having removed the gears there was no turning back!
Will it ever go together again?
My elder son was clearly horrified when I said I was going to take the Van Diemen down to Aldon Automotive to have the ratios changed in the gearbox, so I decided to have a go myself. Now, I know that others can do this job in half an hour under an umbrella in the pouring rain in the paddock but it took me all day and I still haven’t quite finished. Nevertheless, I do feel quite pleased with myself that it’s almost done.
A Hewland Mk 8/9 gearbox before it fell apart in my hands
When I bought the Van Diemen from Martin Pickles he kindly demonstrated how to change the ratios and I videoed him doing so. So, with this video and instructions printed off from the classic formula ford website and a diagram in a Hewland Engineering manual I set to work.
Everything went more of less smoothly except I failed to realise I had no 1 ¼ inch A/F socket and had to dash out to Halfords, who miraculously had one in a bargain bin for £1 (Greg, I know you read this – loads of sockets and ratchet parts in Kidderminster Halfords going for a song).
Then I had a moment when all the various bits on the pinion shaft (named, apparently, pinions, needle bearings, clutch rings, thrust washers, tracks and hubs but which I previously thought of as cogs and ‘other parts’) fell apart and I had a pile of junk in front of me in no particular order and not even all the same way up. That took a bit of sorting out but I got it all back together somehow.
The layshaft in pieces
I changed the 4th gear ratios from 20/31 to 22/28 so setting the top speed at 105 mph, which according to two helpful fellow HSA members should be about right for the hillclimbs I intend to do. Then I put it all back together. This had taken about four hours!
Pinion shaft parts
Then I realised that you could not select any gears! So everything had to come out again and after much head scratching, consulting photos I had taken as I pulled it all apart, the video and the diagrams, I realised I had not matched up the selector forks to the dog rings correctly (or perhaps I had but they had become misplaced as I slotted the stack back into the gearbox casing). I reassembled it and got it back in the car and the selector rods now move nicely. But that is more than enough for one day! I’ll finish the job next weekend.
As far as I got today. Almost finished (I think).
i certainly do read it, thanks for the tip on halfords
whenever i have seen ratios changed, they pull the ratios and stack them upside down one on top of the other in a stack to keep everything in order and then just substitute a new ring when you reinstall
i’ll bet you will have a great sense of achievement when you get it back right again, top work.
i was building up a new cylinder head for my single seater over the weekend…
HTH
I hope that’s not TQF or ATF automatic gear oil in your box Bob? I know some of the FF boys use it for a hoped for reduction in drag – my advise is don’t fall for the hype, get some redline superlightweight motorsport gear oil, less drag and your ratios and dogs will have 70% less wear than ATF
Hi Anon, It’s Comma MT75 gear oil – http://www.commaoil.com/productsguide/view/6/194 . I haven’t looked into it but it came with the car.
Hi Bob, for the record i did a ratio change on Royale F/ford in the pit lane at Brands Hatch in 1980 and it took me 15 minutes.
I guess it would now take me 30 mins due to body decay and age