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RBL |
Posted: Fri Mar 07, 2008 11:52 am Post subject: |
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Quote: |
S3 1.3 boxes are pretty rare in the UK as they were not officially imported (they were sold in Ireland though). |
Hmmmm. Now I'm confused. I'll have to have a closer look.
Thanks for your help. |
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Admin |
Posted: Thu Mar 06, 2008 11:49 am Post subject: |
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Hi
S3 1.3 boxes are pretty rare in the UK as they were not officially imported (they were sold in Ireland though).
All the best
Keith |
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RBL |
Posted: Wed Mar 05, 2008 5:48 pm Post subject: |
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Paul and Keith, thanks for the feedback. It does have the gap for the sensor so it must be a series 3. (The engine came from a Sprint with an S2 'box but when I took off the 'box sump plate, loads of small metal teeth dropped out! - so I got this box as a replacement)
It must be a 1.3 box from the rpm readings - I'm sure it shows 3500rpm (or very close) at 70mph. (The guy that sold it to me said it was a 1.7 box, but there you go). The problem with larger diameter wheels is that you lose acceleration, so I suppose having a 1.3 'box with these wheels is a bonus unless I wanted really low cruising rpm.
Helpful stuff - thanks
Rich |
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paulhide |
Posted: Sat Mar 01, 2008 10:55 am Post subject: |
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Hi RBL, yes you can tell the difference between the S2 and S3 boxes - the S3 boxes have a nick in the housing on one side where it faces the engine, for the flywheel sensor. |
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Admin |
Posted: Fri Feb 29, 2008 7:52 pm Post subject: |
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RBL wrote: |
Can you tell the difference between the s2 and S3 'boxes by looking? Not sure which I have. |
Probably have to lock on output shaft from the gearbox and turn the input shaft and count the turns of the output shaft. Work it out from that. Be fiddly though. Or take the gearbox sump off and count the teeth on the diff.
RBL wrote: |
Knighty, on my Spyder (1.7 8v/ 5 speed), 70mph is 3500 rpm and 80mph is just under 4000rpm. However, I'm running 15" wheels with 195/60 15 tyres - so I would have thought the revs would be lower for any given speed?! |
Those wheels / tyres would make the gearing about 6.4% higher. Almost double the difference between the S2 and S3 gearboxes.
RBL wrote: |
I would have thought that at 70mph, my revs would be lower than 3500 due to the larger diameter wheels?! |
Working it out.
At 70mph your wheels are turning 967 times a minute. With a S2 gearbox having a 10/37 diff that would make it 3577.99 rpm to the diff. With a 1:0.854 top gear that would make the engine be turning at 3055rpm.
With a S3 1.7 gearbox it would work out at 3211rpm.
With a S3 1.3 gearbox it would work out at 3395rpm.
All the best
Keith |
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baiones |
Posted: Fri Feb 29, 2008 4:32 pm Post subject: |
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paulhide wrote: |
Oops! On my dials 6750 for 16v and 6250 for S2 1.7. I guess that definately makes the S2 box shorter. |
Here in Portugal the S2 1.7 QV box is longer than the 16v one .
I've tested both boxs on a 16v .
And by checking the gear values and diff ratio, i got to the same conclusion...
Are you sure your S2 has the original gear box ? |
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RBL |
Posted: Fri Feb 29, 2008 12:01 pm Post subject: |
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Can you tell the difference between the s2 and S3 'boxes by looking? Not sure which I have.
Knighty, on my Spyder (1.7 8v/ 5 speed), 70mph is 3500 rpm and 80mph is just under 4000rpm. However, I'm running 15" wheels with 195/60 15 tyres - so I would have thought the revs would be lower for any given speed?!
(My gauges are Porsche 912 with the speedo running off the front wheel - so the speed is showing correct, as is the tacho)
I would have thought that at 70mph, my revs would be lower than 3500 due to the larger diameter wheels?! |
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Eddie_W |
Posted: Thu Feb 28, 2008 11:50 pm Post subject: |
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Bobber rules! But now my head hurts. So a 3.7 diff for the S2 and a 3.9 for the S3, Alfa must have lowered it so the 16v could keep up with the 8v off the line. HeHe
Regards Eddie |
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paulhide |
Posted: Thu Feb 28, 2008 3:54 pm Post subject: |
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Oops! On my dials 6750 for 16v and 6250 for S2 1.7. I guess that definately makes the S2 box shorter. |
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Admin |
Posted: Thu Feb 28, 2008 12:30 pm Post subject: |
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paulhide wrote: |
What I'm trying to say is that top speed for an S2 1.7 limited to 5650 revs is 117 mph and top speed for a 16v limited to 6750 revs is 135 mph and these gearbox ratios work out at pretty damn similar |
What do you mean by limited? The stock S2 1.7 had a rev limited on the rotor arm set to 6750rpm from memory (and when desperate and using an XR3i rotor arm with a limiter at 6250 or so I kept hitting the rev limiter ).
All the best
Keith |
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bobbber |
Posted: Tue Feb 26, 2008 4:45 pm Post subject: |
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And it's 132mph for a Series III (at least for the cat'd version)?
5650 @ 117 = ratio of 48.29
6750 @ 132 = ratio of 50
Therefore, 96.58% (48.29*2). OR a difference of 3.42%.
I don't think anyone would notice this difference (at least not with the dodgey combination of inaccurate speedo and rev counter)
9/35 = 0.257
10/37 = 0.2703
Difference... 4%
My mathematical genius - clearly wasted on you people!
Bob |
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bobbber |
Posted: Tue Feb 26, 2008 4:35 pm Post subject: |
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Ok ok...
MPH / 0.0197 = rpm
SO...
135mph = 6850rpm
117mph = 5940rpm
BUT... with the lower diff = (5940 * (9/35)) / (10/37) :
117mph = 5650rpm
That's slightly off for the 135mph Series III... but SPOT ON for the Series II @ 117mph...
That ok now Paul?
Bob |
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baiones |
Posted: Tue Feb 26, 2008 2:49 pm Post subject: |
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paulhide wrote: |
(...)top speed for a 16v limited to 6750 revs(...) |
weird...
All the 16v i've seen are limited to 7200... |
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paulhide |
Posted: Tue Feb 26, 2008 11:32 am Post subject: |
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What I'm trying to say is that top speed for an S2 1.7 limited to 5650 revs is 117 mph and top speed for a 16v limited to 6750 revs is 135 mph and these gearbox ratios work out at pretty damn similar |
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baiones |
Posted: Tue Feb 26, 2008 11:14 am Post subject: |
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paulhide wrote: |
If that's true, what would be the revs at 70 in top for both and what would be the top speeds at 5700 revs for the S2 and 6700 revs for the S3 |
I have an excel file at home that calculates that .
You can input the tire size, anda then check the speed at all the gears.
I'll try to find it to post here .
For example, if you put a 33 s2 1.7 QV gearbox on a 16v, and if you could rev till 8000RPMs, that will be almost 274km/h in 5th gear!!!
( thats the one i remember )
7200 ( rev cut on 16v ), it's about 250... |
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paulhide |
Posted: Fri Feb 22, 2008 9:32 pm Post subject: |
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If that's true, what would be the revs at 70 in top for both and what would be the top speeds at 5700 revs for the S2 and 6700 revs for the S3 |
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baiones |
Posted: Fri Feb 22, 2008 4:16 pm Post subject: |
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paulhide wrote: |
I agree with zp. Work out top speeds of all 1.7 series 2 and 3 and compare to max revs and I think you'll find they all have the same gearing ratios. if there is a difference it's very small. |
The gear ratios are the same but not the diff .
you can checkit on this page on the above menu, the gear section :
................................................................DIFF
Alfa 33 series 2, 1.7 QV & Sprint 1.7...........10/37
Alfa 33 series 3, 1.5 & 1.7, including 16 V.....9/35 |
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bobbber |
Posted: Fri Feb 22, 2008 10:46 am Post subject: |
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31.8kph @ 1000rpm.
That's 19.7mph.
70 / 19.7 = 3.55
3.55 * 1,000 rpm = 3550rpm
Bob |
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paulhide |
Posted: Fri Feb 22, 2008 9:35 am Post subject: |
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I agree with zp. Work out top speeds of all 1.7 series 2 and 3 and compare to max revs and I think you'll find they all have the same gearing ratios. if there is a difference it's very small. |
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ZeNiTh-PbArM |
Posted: Thu Feb 21, 2008 8:57 pm Post subject: |
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hi,
just had a book at my user manual and it says series 3 33s fitted with 1.7ie 8V and 16V run 31.8kph @ 1000rpm in 5th gear
regards,
zp |
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knighty |
Posted: Thu Feb 21, 2008 3:26 pm Post subject: |
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paulhide wrote: |
Both my 16v and series 2 read just under 3500 revs at 70 in top, so looks like Bobber is spot on. |
agreed - spot on everyone, thanks very much, I have now specified a final drive ratio and 4th gear ratio that will allow 72mph at 3500 rpm, that equates to 118mph at 6000rpm, which I will never do, but I just want a sensible crusing rpm around max torque......previously it was 4200rpm at 70mph, so its a drastic improvement without the gear feeling too long. |
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baiones |
Posted: Thu Feb 21, 2008 1:23 pm Post subject: |
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Hi.
Series 2 1.7 QV gearbox is longer than the series 3 16v one .
If i recall correctly the difference is in the diff...
I have a friend of mine with an 1.7 QV gearbox on a 16v and you can tell the difference...
It was reving on 5th till 7200 ( 230 ) and now goes further...
( the engine is tunned, i've pusshed a Celica once when i was going at 230 ) |
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paulhide |
Posted: Thu Feb 21, 2008 11:25 am Post subject: |
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Both my 16v and series 2 read just under 3500 revs at 70 in top, so looks like Bobber is spot on. |
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knighty |
Posted: Thu Feb 21, 2008 9:56 am Post subject: |
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not worried if series 2 or 3, some form of actual in-car rpm figure at 70mph would be much appreciated thanks guys |
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ZeNiTh-PbArM |
Posted: Thu Feb 21, 2008 6:45 am Post subject: |
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Hi,
don't trust readings from a drive test as alfa dashboards never tell you the truth
over time, speedometers develop a tendancy to exagerate vehicle speed
and rev-meter underestimates engine revs
i remember Alfa used to write figures in the owners manual for vehicle speed in 5th gear at 1000rpm anyway.
regards,
zp |
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