EFA Posted April 14, 2001 Share Posted April 14, 2001 Also be aware that tyre rolling circumference varies considerably from manufacturer to manufacturer! Chris, Use the gearing calculatio program to figure out waht gearbox is best. I can email it to you if you do not have it. Send your request by email! All you need to know is overall tyre diameter (inches), diff ratio, max rpm and gearbox type. the program does the rest of the calc for you. Arnie Webb The Fat Bloke blush.gif in a not so Slow Vauxhall wink.gif See the R500 eater here See the Le Mans Trip Website here Link to comment Share on other sites More sharing options...
CHRIS CLARK Posted April 14, 2001 Author Share Posted April 14, 2001 Arnie, Thanks. See your mail! Link to comment Share on other sites More sharing options...
Richard J Darnell Posted April 15, 2001 Share Posted April 15, 2001 I had a look at Dave Andrews site and tried his gear ratio program. I measured my 16" wheel and 205/45 tyre combo and found it gives a diameter of 22.5" I have a standard 5 speed box for a 1998 Roadsport (the Classic's 5spd has slightly different ratios according to the handbook) and 3.92 diff. At maximum revs (7,600 rpm for my 1.6k SS) the maximum speed in each gear is: 1st 39mph 2nd 72mph 3rd 103mph 4th 130mph 5th 158mph (clearly and overdrive gear!) For the 6 speed with a 3.62 diff you get: 1st 52mph 2nd 70mph 3rd 88mph 4th 106mph 5th 124mph 6th n/a So 2nd gear is similar for both 'boxes. 3rd gear for the 6 speed fills the gap between 2nd and 3rd on the 5 speed. As most agree, the problem gear on the 5 speed is 1st - even if you take the car up to maximum revs, changing into second drops the car to about 4,000rpm compared to 5,700rpm for the 6 speed. Actually, my only problem with the 5 speed is accelerating hard out of a roundabout in 2nd gear, doing 25mph (say). It doesn' feel natural to change into 1st with only 10+ mph left in it, but in 2nd gear it takes a while to wind the revs up (and means a BMW 330d can hassle me for a short while!!). QUESTION For all you 6 speed box owners out there, how easy/natural is it to change into 1st gear in such circumstances? Link to comment Share on other sites More sharing options...
EFA Posted April 15, 2001 Share Posted April 15, 2001 Very easy. Warning: Youmay read elsewhere on this site that a high set of ratio's (with a nice cruising top gear) will not impact your acceleration once you are in second. I just moved from a 3,38 diff believing the crusing ability the 6 speed gives with this diff ratio was a bonus, only to be beaten by less powerful K Series cars with lower gearing over 1/4 mile runs. I have tested the car with a 3.92 diff and six speed (yes this works out to 5900 rpm at a ton!) but the acceleration is immensely improved. Go with a 6 speed on a 3.92 if you are brave or a 3.62 if you are not! Arnie Webb The Fat Bloke blush.gif in a not so Slow Vauxhall wink.gif See the R500 eater here See the Le Mans Trip Website here Link to comment Share on other sites More sharing options...
CHRIS CLARK Posted April 15, 2001 Author Share Posted April 15, 2001 I assume from this that you would recommend that my new 1800 set up (when I finally get around to sorting it !!!) would be benefit from the 'sixer' ? They haven't yet fined acceleration but they do fine that higher top speed!!! Link to comment Share on other sites More sharing options...
EFA Posted April 15, 2001 Share Posted April 15, 2001 Chris, So long as you don't plan to make too many motorway journeys setting your car up for 5500 -6000 rpm in top at the ton will be fine, and mnaximise acceleration (this pres. being why you u/graded your engine in the first place) If you want to try these ratio's, ( as a passenger in my car) weather permitting I'll be at this months NK meet. Is that sufficient adv. warning for you??? Arnie Webb The Fat Bloke blush.gif in a not so Slow Vauxhall wink.gif See the R500 eater here See the Le Mans Trip Website here Link to comment Share on other sites More sharing options...
Jason Posted April 15, 2001 Share Posted April 15, 2001 Arnie only to be beaten by less powerful K Series cars with lower gearing over 1/4 mile runs. Excuses excuses smile.gif Jason R500FUN Link to comment Share on other sites More sharing options...
EFA Posted April 15, 2001 Share Posted April 15, 2001 Ha, I knew you'd be watching.......... Fun eh??? ('Til you lose)((Badly)) Arnie Webb The Fat Bloke blush.gif in a not so Slow Vauxhall wink.gif See the R500 eater here See the Le Mans Trip Website here Edited by - fat arnie on 15 Apr 2001 20:51:19 Link to comment Share on other sites More sharing options...
Jason Posted April 15, 2001 Share Posted April 15, 2001 Arnie You've set your self very high, it could be a very big fall if it doesn't go your way. When do I get my return on a trackquestion.gif Jason R500FUN The Proven VX eater smile.gifsmile.gif Edited by - Jason on 15 Apr 2001 21:06:49 Link to comment Share on other sites More sharing options...
EFA Posted April 15, 2001 Share Posted April 15, 2001 Jason, You strike me as the kind of guy who knows, if there ain't a long way to fall, it weren't such a big thing in the first place! Arnie Webb The Fat Bloke blush.gif in a not so Slow Vauxhall wink.gif See the R500 eater here See the Le Mans Trip Website here Link to comment Share on other sites More sharing options...
CHRIS CLARK Posted April 15, 2001 Author Share Posted April 15, 2001 Stop hi jacking my thread you two !!!!!!!! Throttle bodies at dawn ? Link to comment Share on other sites More sharing options...
stevefoster Posted April 16, 2001 Share Posted April 16, 2001 So Chris, Did you decide on which box then? Link to comment Share on other sites More sharing options...
Andrew Dent Posted April 16, 2001 Share Posted April 16, 2001 Chris, Throttle bodies at dawn. NO How about the first to 60 wink.gif Andrew Link to comment Share on other sites More sharing options...
CHRIS CLARK Posted April 16, 2001 Author Share Posted April 16, 2001 Having been to see Phil Stewart (Road & Race) for a good look at the internals, upgrade mods etc (thanks Phil) I have to say the 'sixer' is VERY appealing thumbsup.gif Also, the 'idea' sounds good too!!!!!!!! Get my drift ? Link to comment Share on other sites More sharing options...
Pierre Gillet Posted April 18, 2001 Share Posted April 18, 2001 Has anyone measured the improvement in accelerating from 0-60 mph when using a 6 speeder instead of a 5 speeder? Pierre Link to comment Share on other sites More sharing options...
EFA Posted April 18, 2001 Share Posted April 18, 2001 If you use a diff that gives you 60mph in first with the six speed your off the line accel will be the same as a 5 speed which does the same. If however you use a trick clutch like Peter and I have, you can leveage the benefit of a very fast 1st to 2nd change and get better off the line grip/accel. I'm expecting a sub 3 sec out of my car when I get things all sorted. Not on the crappy surface at Brooklands or the Pod though. 3.5s is achievable at Brooklands. Arnie Webb The Fat Bloke blush.gif in a not so Slow Vauxhall wink.gif See the R500 eater here See the Le Mans Trip Website here Link to comment Share on other sites More sharing options...
Clay Head Posted April 18, 2001 Share Posted April 18, 2001 Chris I believe that you had a ride in Phil Stewarts car with his SC box. How did it sound and what did you think? Link to comment Share on other sites More sharing options...
CHRIS CLARK Posted April 18, 2001 Author Share Posted April 18, 2001 Timothy, Forget the preconceved ideas about 'em being noisy; it was very good. I could quite easily live with the slight (and I mean slight) increase in the g/box 'whine'. Nothing drastic at all though. No, overall, very impressed. Me. I just bought a six speed though !!! Link to comment Share on other sites More sharing options...
EFA Posted April 19, 2001 Share Posted April 19, 2001 Thank God....... Arnie Webb The Fat Bloke blush.gif in a not so Slow Vauxhall wink.gif See the R500 eater here See the Le Mans Trip Website here Link to comment Share on other sites More sharing options...
Clay Head Posted April 19, 2001 Share Posted April 19, 2001 Thanks Chris- I am relieved as I bought one and it arives tomorrow!! Just out of curiosity how much was the 6 speeder and what ratios / diff combination is it you have? Link to comment Share on other sites More sharing options...
Clay Head Posted April 19, 2001 Share Posted April 19, 2001 Thanks Chris- I am relieved as I bought one and it arives tomorrow!! Just out of curiosity how much was the 6 speeder and what ratios / diff combination is it you have? Link to comment Share on other sites More sharing options...
CHRIS CLARK Posted April 19, 2001 Author Share Posted April 19, 2001 Timothy, I have a 3.92 non lsd. Should be fun ! Link to comment Share on other sites More sharing options...
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