Straight Cut Gearbox....Pros & cons?
Discussion
Im looking to buy a lovely Westfield at the moment. It ticks all the required boxes except it has a 'straight cut' gearbox. I'm aware that on track they're great but I dont know if I'll be able to live with the whine & clatter on the road. The car will be more of a Sunday lane blaster than a regular track car. Is it possible to live with a road car with a straight cut box, how long do they last, are there any other issues?
Porkie said:
Why would a straight cut box be better on the track?
Only if it was dog engagement surely?
Otherwise just more noise?
I am asking not telling here by the way!
straight cut box is stronger , if it is a dog box the gears can be changed quicker. It is one of those things that some people have for no good reason. One of the guys I knew had a straight cut box in a westfield with a 550 bhp cosworth engine, between the whine of the box and the poping and farting of the exhaust and the hiss of the dump valve it was the worst car on the road I have ever been in. On the track it was awesomeOnly if it was dog engagement surely?
Otherwise just more noise?
I am asking not telling here by the way!
Pros:
- As CraigyMc says, less friction, so the absorb less power.
- As Spaximus says, the gears themselves asre stronger, and because the tolerances on the mesh are much wider they can take more abuse both in operation and assembly (so on mid-engined cars are capable of being stripped in the paddock to swap gear ratios, for instance). Not really a valid advantage for road use, though, unless you have a monster engine with more torque than the standard box can cope with.
- Not directly attributable to the straight-cut gears, but you will often find that straight-cut boxes are also dog engagement, which gives a much faster gearchange and allows clutchless upshifts.
- They are painfully noisy.
- Again not attributable to the straight-cut gears, but if it is dog engagement as well, the the gear selection can be pretty clonky when you're dawdling around town or selecting first at traffic lights. And because the selection is more positive the faster you bang the gears through, it's better with a sequential change as the dog-legs in a H-gate selection slow things up a bit and highlight the clonkiness of the box for road use.
Yep, that's sensible.
It's reasonably valuable second hand, so not much to lose, I guess.
If you do decide you can't live with the noise, I'd strongly recommend that you obtain a standard Type 9 but then get it rebuilt by BGH Geartech before installing it - the examples of Brian Hill's gearboxes that I've driven have been simply superb, and much more suitable for road use than a straight-cut Quaife.
It's reasonably valuable second hand, so not much to lose, I guess.
If you do decide you can't live with the noise, I'd strongly recommend that you obtain a standard Type 9 but then get it rebuilt by BGH Geartech before installing it - the examples of Brian Hill's gearboxes that I've driven have been simply superb, and much more suitable for road use than a straight-cut Quaife.
vescaegg said:
Ha ha, yes that's THE clip that seems to get posted when talking about gearbox whine! I certainly couldnt live with that! 
vescaegg said:
That box + supercharger I would love to hear!Might seem a bit daft in a car, albeit an open one, but when I'm on the bike I wear earplugs if I plan on riding quickly. Wind noise is deafening over a long fast thrash, get off the bike with a headache. Ear plugs transform it, if the noise is a bit too much try some plugs before you sell it.
I had a Quaife straight cut box in my RS2000 rally car, which I did use on the road. Loud yes, but I loved the sound. Livable? Well it was for me, but then again I was in my 20's at the time, so I could put up with it, not sure I would be able to now. Still, as has been said, quite valuable so if you didn't like it you could swap it for something easier to live with & have a little extra cash I would think.
I thought Helical was stronger as more of the surface area of the gears are together at any one point?
or have I go that totally wrong?
I had a gearbox that was a supposed to be a nice compromise on a GTR. Helically cut. Syncro on 5th and on reverse. But dog engagement on the other gears. Good on track for sure.... but the way first gear engaged made it horrible to use on the road. Was quiet though....
Have an Elite sequential in a Westfield thats far nicer on the road to use and doesnt bang into gear.... straight cut though so pretty noisy. If that was helically cut. It would be a lovely box for all occasions if it was just a little more quiet.
or have I go that totally wrong?
I had a gearbox that was a supposed to be a nice compromise on a GTR. Helically cut. Syncro on 5th and on reverse. But dog engagement on the other gears. Good on track for sure.... but the way first gear engaged made it horrible to use on the road. Was quiet though....
Have an Elite sequential in a Westfield thats far nicer on the road to use and doesnt bang into gear.... straight cut though so pretty noisy. If that was helically cut. It would be a lovely box for all occasions if it was just a little more quiet.
I had a straight cut Type 9 box in one of my old Westfields.
They are massively noisy and its not necessarily a great noise once the novelty wears off. They have marginal 'efficiency' benefits over helical boxes and aren't necessarily any stronger, less axial loading, more radial loading, take your pick.
Coming back to the noise, I drove mine 700 odd miles to Le Mans a few years back and despite wearing a helmet and ear plugs, I had a serious ear ringing for weeks afterwards. Fourth gear was 1:1 so no whining and I sometimes ended up cruising in fourth at 6000+ rpm because it was less barbaric to my ears! That's how offensively loud the box was!
It's hard to say anything positive about a SC box in a road car. The ratios in mine were nice but I could have had that in a helical box (a 60mph first gear is very handy btw). In a racing car where every last drop of power counts, its justifiable but daft on a roadcar in my opinion.
ETA Just reread the OP. I'd misunderstood and thought you were thinking of buying an SC box for your car rather than buying a car with one pre-fitted. I'd say go for it on that basis. It'll always be worth something if you want to swap for a Type 9 later on.
I have an in car video of my Westfield with SC box. Will try and figure out how to youtube it or something so you can take a look. It'll not be until this evening though.
They are massively noisy and its not necessarily a great noise once the novelty wears off. They have marginal 'efficiency' benefits over helical boxes and aren't necessarily any stronger, less axial loading, more radial loading, take your pick.
Coming back to the noise, I drove mine 700 odd miles to Le Mans a few years back and despite wearing a helmet and ear plugs, I had a serious ear ringing for weeks afterwards. Fourth gear was 1:1 so no whining and I sometimes ended up cruising in fourth at 6000+ rpm because it was less barbaric to my ears! That's how offensively loud the box was!
It's hard to say anything positive about a SC box in a road car. The ratios in mine were nice but I could have had that in a helical box (a 60mph first gear is very handy btw). In a racing car where every last drop of power counts, its justifiable but daft on a roadcar in my opinion.
ETA Just reread the OP. I'd misunderstood and thought you were thinking of buying an SC box for your car rather than buying a car with one pre-fitted. I'd say go for it on that basis. It'll always be worth something if you want to swap for a Type 9 later on.
I have an in car video of my Westfield with SC box. Will try and figure out how to youtube it or something so you can take a look. It'll not be until this evening though.
Edited by Gad-Westy on Wednesday 24th August 09:10
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