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Diff ratios

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Fastie Officially Full-On Dubber

217 posts · joined Apr 2010 ·

#850014
I'm pretty close to ordering a Racho street pro. Just wondering if someone could tell me the difference in revs sitting at 100kph between 4.1 and 3.8.
3.8 is a $400 upgrade.

Fastie Officially Full-On Dubber

217 posts · joined Apr 2010 ·

#850254
$59/ You can get them from Mick motors in QLD

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#850285
Fastie wrote:I'm pretty close to ordering a Racho street pro. Just wondering if someone could tell me the difference in revs sitting at 100kph between 4.1 and 3.8.
3.8 is a $400 upgrade.
Hi

3.88 TO 1 AND 4.125 TO 1

DON'T know the speed differences offhand
but the $400 is too expensive...
use larger tyres instead

Lee
- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

tweety Wolfsburg Wizard

460 posts · joined Feb 2011 ·

#850783
Going to larger tyres?

use this calculator

http://www.tacomaworld.com/forum/tirecalc.php

but wouldnt he want to go to smaller tyres?

going from 4.1 to 3.8 means he wants to lower the gearing...make it take off quicker, less top speed etc.

From a novice...
www.youtube.com/watch?v=HXwh4z8d66o
SUBARU ea81, VW auto, Detour camper
My ex girlfriend said "its me or a trike". Her big mistake.

Craig Torrens 6 times Australian, 7 times State Hillclimb Class Champion

8,040 posts · joined Jan 2003 ·

#850794
Fastie wrote:I'm pretty close to ordering a Racho street pro. Just wondering if someone could tell me the difference in revs sitting at 100kph between 4.1 and 3.8.
3.8 is a $400 upgrade.
About 6-7% difference.............so if at 100kph it was at 3000rpm with the 4.1 diff, then the revs will drop to 2830rpm with the 3.8 diff.


Craig Torrens 6 times Australian, 7 times State Hillclimb Class Champion

8,040 posts · joined Jan 2003 ·

#850796
tweety wrote:going from 4.1 to 3.8 means he wants to lower the gearing...make it take off quicker, less top speed etc.

From a novice...
No, going from a 4.1 to 3.8 is making the gearing higher.........higher top speed, slower take off.


matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 ·

#850797
With 26" rear tyres and .82 top, 4.125 diff gives 3000 rpm=109.8km/h, and a 3.88 diff, 3000 rpm=116.7km/h; with a .89 top and same 26" rubber, a 4.125 diff gives 3000 rpm=101.2 km/h and 3.88, 3000 rpm=107.6 km/h
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

HappyDaze Superannuated

2,887 posts · joined Jun 2009 ·

#850837
Well done Matt.👍 I'm sure that is EXACTLY what Fastie wanted to know - no bullshit, just the facts!
I'd rather wear a Beetle out by racing it than by polishing it!

Fastie Officially Full-On Dubber

217 posts · joined Apr 2010 ·

#851353
Exactly. Cheers mate