Planned upgrades for next year.

[robin]

Nice. All 1st/2nd gear I assume?

[Dominic]

I think it was all in first gear from memory (with a little reverse ).

[alicrozier]

The (much hated) S2 111S box has a longer second gear that means it does ~70mph at 7,200 RPM I think. If fitted to a car with standard cams (i.e. non-VVC) you really notice the drop into 3rd and you really feel like you have to take it all the way to the limiter in 2nd otherwise it bogs down in 3rd. So for fast road/track use I think that longer 2nd is too long without some engine mods to better utilize it. The standard second is not that much shorter - ~60mph IIRC - so if it's "too short" there isn't much gap between that and what's "too long". I think the 2nd gear is the same effective ratio in CR and normal boxes?

Cheers,
Robin

The S2 111S has different ratios and final drive but actually works out with a shorter 1st & 2nd gears than the standard S2 close ratio. As you say peak power is 7K rpm as opposed to 5.5...3rd, 4th and 5th longer hence the apparent big step from 2nd (S2 111S will pull 100mph in 3rd).

Speeds by gear at 1,000rpm and optimum below (optimum change on the S2 111s is always at the rev limiter):

S2 (std close ratio) @ 6.5K (or optimum based on normalised torque curves) rpm
1st 6.05 39.3mph
2nd 10.11 65.7mph (6,500rpm)
3rd 13.53 85.3mph (6,300rpm)
4th 17.12 106.2mph (6,200rpm)
5th 20.86 135.6mph

S2 111S @ 7K rpm
1st 5.84 40.9mph
2nd 9.98 69.8mph
3rd 14.49 100.8mph
4th 18.86 132.0mph
5th 22.18 155.3mph

[smee]

Dom needs 50p.s.i. and complete disregard for his car

You have all saved me a lot of money. Off to look for a CR box, I may be some time.

Thanks

[steviej]

Link to list of gearbox codes, ratios etc, it may help to check if someone is selling you one your not sure of.

wiki.seloc.org/a/Rover_PG1_gearbox

p.s. if you find one with the lsd, I would be interested if your not going to use it

[cla5h]

Using Ali's figures, the standard s2 with CR box will deliver 85mph when topping out in 3rd, whereas the VVC will deliver 100mph with its non-CR box.
If pairing the CR box with a VVC, and allowing for being able to rev it further, one could get to 95mph? So, still a little short of the 100mph the non-CR box would deliver, but is this outweighed by avoiding the rev drop experienced due to the gap between 2nd & 3rd? i.e. is it worth putting a CR box in a VVC car (forgetting about 5th gear economy.)

[robin]

It probably is, depending on what you're trying to achieve.

The CR box was originally fitted to the S1 VVC cars I think.

The closer your ratios the faster the car will accelerate (though this is moderated by the number of gear changes you'll have to make), provided you change gear at the correct RPM (the limiter in general for a VVC engine). The reason is simply that the rev drop to the next gear is less on the closer ratio boxes, so you drop from 7,200 to 5,000 RPM instead of 4,000 RPM. Your engine is making more power at 5,000 than 4,000 and so your average power used goes up and you must accelerate faster.

So for a track only car you want top gear to be just tall enough to reach the max speed you'll need (e.g. 125 mph would be enough for many circuits) and then stack all the other gears up underneath aiming for 2-3K per gear change for the typical K series.

However, this gearbox will drive you mad on the road where you want to do 80mph with 3,500 or less ...

If you're not against the clock, why bother with the shortest possible ratios ... at that point you're probably as well to stick with the standard box, IMHO.

Cheers,
Robin

P.S. Fitting some cams that shift the torque further up the rev range will probably make as much difference as the CR box, is cheaper to do and makes your car faster to boot.

[Shug]

Once more I find myself disagreeing with Robin (hope it's not a trend, that may indicate madness on my part...)

CR box, yep it's a bit more annoying on the motorway and you get marginally worse economy. Very much depends on how you use the car - if you're really that concerned about its motorway manners, should you really be in an S1? I'd say no - get some earplugs and man up. If it's for blatting about, it's about a million times better as the car is always up on it's toes - obviously track as well. The increased revs/engine braking at most points makes the car more reactive to inputs - it's not the acceleration I notice most on a standard gearbox'd car now, its the slightly less 'alive' chassis feel. Makes it the sports car it should be. It's a feel thing and I think the tradeoff in motorway manners and economy is well worth it.

Also, from the LSD point of view - I have one (torsen, not Quaife), simply because the gearbox I was buying and modifying had one for good money. I've got several open diffs that could go in if it was a pain. The LSD is still in there. From the road POV, you never notice it at all. On track, it makes the breakaway a little snappier, but its easier to keep it at big drift angles with more throttle control. No longer is it a case of going sideways for as long as the momentum will let you as one wheel spins away the power - you can modulate it on the throttle very easily with an LSD. Needed? Absolutely not - Fun if you get one cheap? Definitely.

[campbell]

if you're really that concerned about its motorway manners, should you really be in an S1?

Hell yes!

[robin]

I guess what I'm saying is that in my experience there isn't that much difference between driving the two in anger and one is much nicer at all other times, so for me (S2 owner, no earplugs ) I decided that the actual performance improvement gained from the CR box did not make it worth keeping.

Younger blood (S1 owner, bleeding ears ) will no doubt prefer the CR box ...

Cheers,
Robin

[alicrozier]

If using an S2 box on an S1 don't forget to factor in the smaller wheels...will give 5-6% shorter gearing.

[tut]

Younger blood (S1 owner, bleeding ears ) will no doubt prefer the CR box ...

Cheers,
Robin

Spot on Robin………

tut

[hiscot]

- upgraded clutch hose ( I still have the red plastic one)
A must mine failed away from home on a very hot day
- upgraded gear linkage kit
not required I have short throw stick but agree bell crank striped greased and readjusted will transform the box and adjustment will remove any slack / sloppy gearchange
- electric fan switch
not required imo
- oil gauges
I liked the oil temp as it informed me of the true engine temps and when it could be ragged
- sport 160 throttle body
not required imo
- lightweight fly wheel (eliseparts)
cheap enough if fitting a box / clutch gives a slightly better spin up
- upgraded toe link kit (elise shop)
road use not required imo
- CR box (where and which one)
yes love it but mine is very short, std box is far too wide esp with std engine output it becomes a 4 speed with overdrive not a sports car mgtf box is a good halfway gives a useable 5th and very cheap
- LSD (used?).
I use a quaife and like the feel it sorta links the throttle to the wheels

[kenny]

Dom needs 50p.s.i. and complete disregard for his car

You should have seen him at Ingliston during 'free practice'. That poor car.

[Corranga]

- sport 160 throttle body

It's worth switching to an all metal throttle body as they seem to suffer less from sticking. I'm not convinced that the bigger throttle body will make the engine make more power. What is worth doing is removing the shoe from the back of the throttle plate as this makes the throttle response sharper (and is free).

I liked the effect the 52mm throttle body had on my car (sls stage 1 head, valves etc, standard cam, 4-2-1 manifold), but if you want it only for no sticking, just buy a metal 48mm one. There is usually plenty on eBay for very, very little!
I picked my 52mm up on eBay for something like 50 quid new though, so there are bargains to be had (compared to the EP price anyway!)

Chris