Transverse of longitudinal

[Team27]

Hi

Could anyone explain to be a major advantage of using either a longitudinal or transverse gearbox configuration?

The only real differences I’ve found so far are for packaging, if running a diffuser there is an advantage to a longitudinal configuration as the gearbox casing can be comparatively narrower. Also the bearing for the bevel gear sees a greater thrust loading for a longitudinal box requiring a different more substantial bearing

Please if there are any gearbox specialists or anyone who knows the name of the only book written on gearbox designs the help would be much appreciated

[greenamex2]

As nobody has replied with anything sensible I shall throw in my tuppence worth -

The selection seems to be one of OVERALL packaging. In my kit car (short wheelbase) the only way you can fit the engine in is transversely so you are 'stuck' with a transverse gearbox.

Depending on the weight of the engine and the vehicles wheelbase this is not necessarily a bad thing as you get a nice compact engine, the weight distribution is not too bad and you don't get 30 odd KG of transmission overhanging behind the rear wheels.

Obviously in a longer wheelbase vehicle then the weight distribution issue becomes more critical so a longitudal mounted box starts to make more sense.

Of course you can get 'transverse' gearboxes for longitudal mounted engines. However these require the engine to be mounted further forward, or the driveshafts sloping backwards so are not suitable for every installation. However they do get round the overhang 'problem'.

You also mentioned about the rear diffuser. Look at the back of an Elise/Exige. A tranverse gearbox means you can get a really good full width diffuser compared to a longitudal gearbox.

[Team27]

Thanks for that i thought everyone was ignoring me.

Seems to be pretty much as i thought, after all a gearbox kinda fits with the rest of the car rather then the car bowing to the gearbox requirements!!

Talking about the diffuser i should have made myself clearer i was on about single seater racers. But you are right even some of them use transverse configurations.

Still looking for that one book that has been wrote about transmission sytems, may have to get the typewriter out myself..

Cheers

[greenamex2]

I'd buy it, a much ignored but totallty crucial subject.

My kit was totally ruined by a poor gear changed, spending a day correcting the linkage made it so much nicer.

Boy am I looking foward to the ex Touring Car sequential box!

[Team27]

Cool ill get onto it straight away. Just watch out if its an ex Volvo touring car box i heard a story about them having 5 reverse gears and one forward!!!!

One other question, chain drive or gear drive?

Ive read that spur gears have an efficiency of around 99%. This is obviously in ideal conditions and is not so much of an average but a maximum.

Chain drive has slightly lover values for efficiency, when the tension in the chain has been correctly set and depending on chain wear.

However if a large distance needs to be covered which will be more efficient, a number of gears or a single long chain. My understanding is that although a single set of gears is more efficient where there are a number of them meshed in series the efficiency reduces to less then that of the chain?

Thanks

[greenamex2]

The gearbox bloke did have some of the Honda boxes when I got my one (Renault). And yes, I would have had 6 reverse gears and one forward. I tried to convince my engine builder to build a reverse running V6 but he wasn't interested!

Pass on the chain stuff, even my motorbike is shaft drive.

[Team27]

Hi

Sorry still on about gearboxes

Could anyone give me a rough estimate of gearchange times for a H pattern manual gearbox compared to a sequential system? Apart from reduced time to change the gear, reduction in the chance of a "botched" change, and the allowance of flat shifting what other advantages are there to using a sequential box?



Thanks

[greenamex2]

Assuming dog engagement and clutchless up changes for both I would expect the sequential change to be about 2/3 the time of a simple H pattern change (eg 1-2 4-5 on a normal H pattern box) and half the time for the awkward H pattern changes (eg 2-3 4-5 on a normal pattern box).

On my H pattern dog box I can change gear in about 0.3 seconds ish according to the data logging.

Not a lot of saving on it's own but count how many changes a lap and you can easily drop the lap time a second or so!

In reality the sequential box is going to be so much easier that the typical gear change is going to much closer to the 'optimal' time.

Then factor in the fact that most H pattern gearboxes are 5 speed and most sequential are 6 then you have a further reduction in lap time, assuming you are taking advantage of the gearing of course.

[TEAM78]

Ive seen gear changes of 0.2 seconds on a H gate, done by a few drivers as well

[Team27]

Hello again,

Another box related question.

Does anyone have an idea if the Motec ECU systems have inbuild programs that allow the programming of a CVT transmission.

Thanks team 78 for that last comment very useful

[Notso Swift]

I know they have started doing drag stuff for Auto's (I think it is a plug in)
CVT - Cant say
I would contact Motec Tech Centre, they are pretty good with assistance via the Web site WWW.MOTEC.COM.AU is the best bet