which gearbox?

[hardtail]

i am running a 2.0 vauxhall in standard trim with 45's, i am thinking of changing my box for better and more rapid acceleration,60 in 1st gear, if thats not too daft. also! does anyone have any advice on modifying my head without spoiling the driving pleasure.

[R500 CYA]

Which gearbox do you have and how do you define greater acceleration?

 

For example 60 is theoretically possible in first gear with the right gearbox, diff and wheel combination, but the strain on the clutch (both component and left foot) will make normal driving very unpleasent.

 

The comparative lack of torque of your engine will make bogging down, stalling and miserable town driving an absolute norm.

 

If however you are looking for faster acceleration out of corners, on the road or track, it may be that you actually need to reduce the gearing, changing the diff for something shorter (like a 3.92 if you are using a 6 speed) will give you a much closer stack of ratios and actually help you go faster. (Just play with the gearing on any car on Gran Turismo if you don't believe me).

 

It will of course mean you will be thrashing the nuts of it on long runs, and my car does 6100 rpm at 100 mph which makes no sense at all if touring, however having the right gear for most bends on the track more than compensates.

 

 

[Alex Wong1697456877]

I suspect 60 in first with a standard Vx will be slower to 60 than if you had a gearchange on the way. Not wishing to be repetitive, but a good value box is SPC's close ratio semi helical Quaiffe box. Not too noisy and much better ratio's than a standard type 9. Mine's proved (touch wood) to be pretty durable and seems ok with my tuned Vx.

[Paul McKenzie]

Hardtail,

I have the same gearbox as Alex in the same car as yours, and it's highly recommended. In practice it can do about 48mph in 1st on 16 inch wheels, and like the others I don't really think you would benefit by a 60mph capability in first.

If you want faster 0-60, then you really need a diff. change down from the standard 3.92.

In reality the move to the SPC box removes the hooligan screaming tyres standing starts with the standard engine, but the much better ratios compensate for that slight disadvantage.

Paul

[hardtail]

thanks for your speedy response boys. the box you describe, would it as pinky says be screaming its nuts off at a ton or is it a good allrounder? and what sort of money should i expect to pay for one?

[EFA]

Peter Carmichael is an advocate of the 60 in 1st gear configuration.

 

For best acceleration aim for aroun 6.2 mph/1000rpm in first gear - much higher (i.e. over 7mph seriously blunts off lie acceleration.

 

Also the lower the gear ratio, the less distance required from engaging the clucth to hitting the top of the torque curve. This gives better traction thus better acceleration.

 

I ran a 6.22 1st gear at Brooklands when I did a 3.38sec 0-60 on A33 ACB10's. on a decent surface with Hoosiers a la Dave Edmunds I would imagine the time would easily been sub 3 secs.

 

To minimise the delay on the gearchange you do need to have a low inertia engine. A sequential box would make things even quicker...........

 

Fat Arn

The NOW PROVEN R500 Eaterid=red>

See the Lotus Seven Club 4 Counties Area Website hereid=green>

 

[Paul McKenzie]

Hardtail,

4th gear is the same you have now and 5th is just a little shorter so the thing isn't screaming at 100mph.

Price was £1116 inc. VAT 15 months ago.

Paul

 

[R500 CYA]

Hardtail,

 

I use a standard 6 speed box with a 3.92 diff and 13 x 6 ACB's. My 156 bhp car does 0-60 in 4.5 secs with a change at 48 in first and 61 in second.

 

I am considering a 3.62 for taller gearing but for track use I think this is unnecessary. I have seen the limiter in 6th on the road and track, which is a calculated 128 mph but it's such a rare occurence I think it is worth the acceleration I gain with the 3.92. Maybe I'll change that after the head has been reworked, but if Arnie uses a 3.92, it's good enough for me!

 

Nick

[Petrolhead]

Hi Ian

 

The SPC is probably your best bet. If you could stand the noise, a 2nd Hand SC Box. Remember the VX car that Neison had for a while. Sounded great through the town but like I say could get sick of noise. There is an other thread and someone has a SC box but with a helical 4th and 5th gear. Sounds like a canny compromise.

 

As for your head - wear a hat with holes in the sided so that you can still hear the noise!! smile.gif

 

By the way, did you see the thread on Chit Chat about Seveners in the North East. They are concidering a run out this Sunday. Have a look here - http://www.blatchat.com/topic.asp?topic_id=11527&forum_id=1&forum_title=ChitChat&M=True&S=True&Topic_Title=Calling+all+North+Easterners&P=False

 

Peter

 

Edited by - petrolhead on 27 Feb 2002 20:29:53

[hardtail]

thanks for that one pete! think i`ll keep an eye open for a second hand spc, i`ll check out that site and let you know any details, you might want a run out with me?