12 replies to this topic

[The Old Bailey]

I've searched and read various opinions but an still on the fence...

 

This is a road car based on 1991 cooper 1330 with MG/S valve spec head done properly etc SW5 (probably with 1.5 rockers) 1 3/4 carb

Final drive changed from 3.1 to 3.4

 

Estimating 80-85bhp

 

Car won't be on a track and doesn't spend much time on a motorway so aim is for good acceleration rather than top speed

 

An option is to use the clubman SC CR gear set but not use the SC drops 

 

Or stick with the original box ratios

 

Using guessworks calculator it seems the CR ratios will potentially allow the car to hit 60 in 2nd which I'm assuming will help potential acceleration.

 

So is the Mini spares
http://minispares.co...48.aspx|Back to

 worth adding to the build?

[DeadSquare]

If your engine has a narrow power band, for example 6,500 - 8,000 RPM, as the car accelerates to 8,000, the correct close ratio allows you to catch 6,500 and accelerate on again.  A long ratio might drop you in somewhere like 5,000, where they may not be enough power to continue accelerating, to get the engine back up to 6,500.

 

This is not a situation that is likely to happen with an SW5 cam on the road.

 

The Single Cam Anglia engines in the 1960s Formula 3 cars had two ratios to get off the line and a choice of five coming out of the corners..

Edited by DeadSquare, 04 July 2022 - 07:50 PM.

[imack]

One problem with the sccr gearsets is that they give a very tall 1st gear, you may need a 3.65 or 3.75:1 final drive to compensate, this will mean higher rpm for a given speed in top gear than a 3.44 will give.
The factory close ratio S/GT helical gearset might be a better option, it works well with the 3.44:1 fd.
http://www.minispare...px|Back to shop

[whistler]

One problem with the sccr gearsets is that they give a very tall 1st gear, you may need a 3.65 or 3.75:1 final drive to compensate, this will mean higher rpm for a given speed in top gear than a 3.44 will give.
The factory close ratio S/GT helical gearset might be a better option, it works well with the 3.44:1 fd.
http://www.minispare...px|Back to shop

The 3.44 FD is fine with SCCR box.

[sonscar]

I find 0 to 60 figures purely academic,most shopping electric vehicles will out gun you with no effort at all.All you end up doing is breaking things and attracting interest from the wrong?right? type of people.I find that 40 to 60 or 70 much more valuable.Just an elderly drivers perspective.Steve..

[whistler]

Following on from Sonscar's comments you'd be better off looking for torque lower down the rev range. My wife's 1330 with Minispares evo001 cam, MG Metro head and HIF44 made 89 bhp with 88 ftlb torque on a recent RR tune up. With 3.44 FD and SCCR box.

[The Old Bailey]

Whistler

Sounds like your spec is very similar to mine…how loud is your wife’s car?



Appreciate the 0-60 comments doubt I’ll be beating any GTI’s off the lights but will be better than the 11sec 0-60 that was standard…

[Cooperman]

The big problem is that unless you use a very low FDR, like 3.9:1 or 4.1:1 with a SC CR gear set, to pull away the clutch needs to be slipped a lot and that reduces the acceleration.

SC CR gears are designed to keep the engine 'on the cam' when you have a 'hot' cam and thus a narrow power band. It is then possible to keep the revs between, say, 5000 and 6500 rpm in all gears at all times.

That is fine for race and rally use, but not for the road, especially if you have to pull away uphill.

I do recall once trying a 3.4:1 FDR with a SC CR gear set and a 544 cam and the clutch didn't last long. A standard gear set would have given better results.

Another option is the original standard Cooper/Cooper 'S' gear ratios which often used to be referred to as the 'Clubman Gear Set. That has a slightly higher first 3 gears, but not by much.

[Spider]

This is what frustrates me with Swifty's Cams.

They may well be very good, but there's no advertised timing figures from Swiftune and likewise no estimated powerband.

 

Without such information, things like gearsets and final drive ratios are only a stab in the dark.

[Northernpower]

I agree with the other comments, the high first gear on the sccr gearset will be a real pain with a 3.4fd. You'll find the time spent slipping the clutch will slow your acceleration at the traffic lights GP. If you drive it hard off the line you'll have to slip the clutch and you'll end up hating the bolts at the back of the wok when you keep changing the clutch. If you want to stick with the 3.4fd look at the clubman ratios, still not great but better than the sccr with 3.4fd.

[mini13]

clubman ratio's?  that the same as the old ST ratio's isnt it

 

basically your choice is the std gearkit with a 3.6:1 first,

the "close ratio helical S kit"  with a 3.2 kit

the SCCR kits which all have a 1st around 2.5

then theres the proper race stuff which has 1st around 2.3, which are way to high for the road.

[DeadSquare]

I've searched and read various opinions but an still on the fence...

 

This is a road car based on 1991 cooper 1330 with MG/S valve spec head done properly etc SW5 (probably with 1.5 rockers) 1 3/4 carb

Final drive changed from 3.1 to 3.4

 

Estimating 80-85bhp

 

Car won't be on a track and doesn't spend much time on a motorway so aim is for good acceleration rather than top speed

 

An option is to use the clubman SC CR gear set but not use the SC drops 

 

Or stick with the original box ratios

 

Using guessworks calculator it seems the CR ratios will potentially allow the car to hit 60 in 2nd which I'm assuming will help potential acceleration.

 

So is the Mini spares
http://minispares.co...48.aspx|Back to

 worth adding to the build?

 

 

Several of us have expressed opinions, but not answered the questions.

 

Last question:- .....  No. 

 

1)  Although the Mini Spares ratios are pretty close to the original Cooper S optional ratios, the optional ratios were there for homologation in the works Rally cars, and a lot of very successful  driver used the standard ratios with a 3.44 diff.

2)  Straight cuts are noisy;  OK at first, but after a few months the excitement wears a bit thin.

3)  Stick with your standard helicals and save your money to spend on fuel.

 

Add to this, your choice of an SW5 cam, which clatter like an old fashioned typewriter, and you will soon be asking about the best ear plugs.

 

If you hadn't bored it out to 1330, which doesn't leave much for the head gasket to bite on, I'd have suggested just fitting a supercharger, sitting back, and enjoying all that torque giving you effortless acceleration, because torque is what you need, not peaky BHP.  If you haven't bought an SW5, or even if you have, fit an Evo 001, it is quieter and has a broader torque band

 

[coopertaz]

have run minispares sccr set in my car with both mg metro and evo001 minispares cam, fitted with 3.44 diff and 1330cc. yes first is longer but no problem setting off and gets rid of gap between 2nd and 3rd, obviously silent in fourth as mainshaft locked. do not try lower than 3.44 though then you do have problems. as said above sc drops very noisy for minimal gain.