Author Topic: need some gear box advice  (Read 3861 times)

February 14, 2008, 05:31:22 pm

oldskool rich

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need some gear box advice
« on: February 14, 2008, 05:31:22 pm »
since ive done all my mods ive had loads of trouble with clutch slipping, most noticeably if i put it in 5th before 70mph and put my foot down it just slips. also in 4th. its a new clutch too

also im running 13" wheels with low profile tyres, im having trouble hitting any decent top end. at 110 mph im doing 6000 rpm and at that many revs i hav no more power to giv, acceleration up to about 95 is fanominal. i need another gear, or to change some ratios somewhere along the line. i would like to hit 150 atleast, im sure the powers there.
im running a tdi rod change box atm, thinking of using a cupra R 6 speed box, wud this help me? what wud i need to change? im guessing they wud use a more heavy duty clutch

i dont know anything about gear boxes btw


f6squared I.D.S.T

Reply #1February 14, 2008, 06:34:26 pm

smoken u

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need some gear box advice
« Reply #1 on: February 14, 2008, 06:34:26 pm »
more top end can be gained with larger wheels, like a set of 14's, although your acceleration will be slightly slower.

Is your clutch cable the self adjuster?, sometimes they stretch too far and no longer adjust.
1990 VW jetta 1.6 td, 2.5" exhaust, no muffler, governor mod 2010 edition, K&N filter. and now 66 hp and 136 ftlbs.
project 1.6 liter in the works  :)
-------------------------------------------------------
You don't rev a VW diesel, you increase the clatter.

Reply #2February 14, 2008, 07:27:34 pm

oldskool rich

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« Reply #2 on: February 14, 2008, 07:27:34 pm »
Quote from: "smoken u"
more top end can be gained with larger wheels, like a set of 14's, although your acceleration will be slightly slower.

Is your clutch cable the self adjuster?, sometimes they stretch too far and no longer adjust.


im not prepared to change my wheels, ive just got new arches and 14 wud scrub. theres got to be another way. the bite point is very low, i dont think the cable is a problem.


f6squared I.D.S.T

Reply #3February 14, 2008, 07:56:50 pm

RabbitJockey

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need some gear box advice
« Reply #3 on: February 14, 2008, 07:56:50 pm »
custom gears?
01 Jetta TDI 100% stock daily
81 Rabbit:TDI-M ported head, Frank06 cam, PD intake, hybrid T3 turbo, Renault intercooler, Syl20 11mm pump, light weight fw, and yellow California Clutch clutch kit

Reply #4February 15, 2008, 06:16:24 am

oldskool rich

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need some gear box advice
« Reply #4 on: February 15, 2008, 06:16:24 am »
is anyone running a cupra 6spd box? cud this be the answer?


f6squared I.D.S.T

Reply #5February 16, 2008, 02:54:29 am

regcheeseman

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need some gear box advice
« Reply #5 on: February 16, 2008, 02:54:29 am »
Thought about a 4 puck clutch mate?I think gibber went through two stock clutches before opting for the sachs item.

how does the tdi rod change fit? is it an 020? have you got the 100 or 90mm clutch? and does it need 100mm CVs?

Reply #6February 16, 2008, 04:59:58 am

Patrick

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« Reply #6 on: February 16, 2008, 04:59:58 am »
6000 rpm @ 110 mph (about 180 kph?) seems pretty high. I think you need to find another gearbox with taller gearing. Have a look here to see what trans you have and what you should look for.

http://www.4crawler.com/Diesel/VW_020_transmission.shtml  or
http://www.scirocco.org/gears/

Have a look here to see how to swap in a higher ratio 5th gear.

http://www.jwsvws.com/020%20Transmission%20Guide.html


Lower number differentials and lower number overdrives (5th gear) will give you more top end. I'm running one of the standard trans (3.94 with a .75 final) and the scirrocco site calculates 4655 rpm at 110 mph with 185/65r/14 tires (my current snow tires). Lots of options available that are in this range or faster, without going custom. Play with the chart. In theory you could have a .367 final with a .71 overdrive, although I don't think volks ever sold it that way.

Sounds like you need a clutch too. Something to watch for, (a mistake I made already!!)  If you have someone turn the flywheel, make sure they take teh same amount off the mounting surface for the pressure plate that they take off the face that contacts the disc. If you don't you'll get slippage because the pressure plate is farther from the flywheel than it should be. Been there, done that!!! :oops:

Reply #7February 16, 2008, 11:46:43 am

hillfolk'r

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need some gear box advice
« Reply #7 on: February 16, 2008, 11:46:43 am »
i had the same problem with my old td
1.6,7A box(very wide ratios),,,turned up boost+pump....
then i got a centerforce dual friction clutch,it was ok in the td
its junk,i cant see any upgrades done to it,except the dual friction disc
its single straps on the PP are like stock
when i used it in my tdi-m it would slip
after a weekend at the drags,i broke the pressure plate straps
IMO,i like clutchnet clutches
im running the red with a 4 puck
it has double straps  
if you run a 4 puck with a stock single strap PP,you will eventually probably break the straps if you hammer it
it engages smoothly,heck i can drive it with work boots!!
i used to drive it daily,till my new job gave me a work truck
never slipped yet
it cost about 400$ us
they recommended a red PP with a yellow disc ,but i went for the extra safety and torque holding of the red disc

i believe the website is
clutchnet.com




say hi to Scirocco
Throttle cables ftw

Reply #8February 16, 2008, 05:28:13 pm

oldskool rich

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« Reply #8 on: February 16, 2008, 05:28:13 pm »
wow thanx guys, very helpfull stuff

so i can change my final drive with a first gear to make up for my stupid wheels?

if i use the gears off a 4speed box will that meen that there weaker?

i think that 4th off the 4 spd is 0.70 so it wud make a gud 5th and 1st is 3.45 which wud be a nice final drive.

hello 150mph

those clutches look great, and pretty cheap too.

will defo be getting one of them
what about fly wheel, will mine be ok? can you get lighter ones?


f6squared I.D.S.T

Reply #9February 16, 2008, 08:27:23 pm

hillfolk'r

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need some gear box advice
« Reply #9 on: February 16, 2008, 08:27:23 pm »
Quote from: "oldskool rich"
wow thanx guys, very helpfull stuff

so i can change my final drive with a first gear to make up for my stupid wheels?

if i use the gears off a 4speed box will that meen that there weaker?

i think that 4th off the 4 spd is 0.70 so it wud make a gud 5th and 1st is 3.45 which wud be a nice final drive.

hello 150mph

those clutches look great, and pretty cheap too.

will defo be getting one of them
what about fly wheel, will mine be ok? can you get lighter ones?


1st is 3.45 and cant be changed
all i know is: i can use a 3.67 r+p from a gas 8v mk2 inside my mk1 7A box
i dont know if you can use 4 speed gears in a 5 speed box
heres a pic of my flywheel,sorta,,i am busy with a project
i turned the weight off with a lathe
 :wink:
also in this pic: name the stuff that WONT be going back in the car :lol:
the light flywheel is a great addition to the clutchnet setup
i think a stock flywheel is like 13-14 pounds
when i was done,mine weighed barely 7 pounds
revs up very nicely,just be a little heavier on the throttle on takeoff,cause now you can stall it easier,thats the only setback
i figured go overboard on the clutch
guys with 16vt's run em doin 12 sec. 1/4's with good results ,works for me
Throttle cables ftw

Reply #10February 17, 2008, 04:04:47 am

Patrick

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« Reply #10 on: February 17, 2008, 04:04:47 am »
I don't think you can use 4th out of a 4 speed to replace fifth in a 5 speed. Fifth is an add on at the end of  the box. YOu can (as far as I can tell) change any fifth for any other fifth,so if you want super high gearing on top, find a gasser box and put the .71 fifth gear in it. Even one of the more standard 3.94/.75 or 3.94/.71 boxes would be a big improvement. Remember: The taller the gears, the faster you're top end, but you'll also be giving up acceleraton in return. There is such a thin as tooo much gear.............

Also, if you go shopping at the wrecker's, keep in mind that while these trannys are in mk 1 and mk 2 cars, the mounts aren't always the same. Some trannys have different bolt patterns at the back end and won't accept both styles of mount.............

Reply #11February 17, 2008, 08:57:37 am

hillfolk'r

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need some gear box advice
« Reply #11 on: February 17, 2008, 08:57:37 am »
i actually had a crazy idea for my application
i cant remember the trans code but its from an 81  na diesel 4 speed
its the tallest 4 speed made with a .71 4th
i was thinkin i could save myself a shift in the 1/4 by going to a 4 speed and still have the top end speed the same
its got the torque to pull it i think......
Throttle cables ftw

Reply #12February 17, 2008, 09:10:48 am

subsonic

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need some gear box advice
« Reply #12 on: February 17, 2008, 09:10:48 am »
This one?

GY Diff 4.17 (1st)3.45 (2nd)1.75 (3rd)1.06 (4th)0.71 N/A 3+E Pick up
2009 Jetta TDI Loyal edition, 6-spd. 16V 2.0CR


1985 VW Golf 5-spd, 4-door, 1.6NA  Bought from orig. owner in Savannah with 42,000 miles.
"Making the jump NA to TD" slow but sure.

1980 VW Rabbit LS 5-spd, 4-door 1.6NA almost 450,000miles  RIP

Reply #13February 17, 2008, 09:59:35 am

hillfolk'r

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« Reply #13 on: February 17, 2008, 09:59:35 am »
no,it was a non pickup model trans
it had the usual 3.89,or 3.94 or whatever
it would bounce off the governor in 3rd at around 65 mph
never was able to get it over 80 or so,it was too tall for an na
i wanna say
1st 3.45
2nd 1.75
3rd 1.03
4th .71
Throttle cables ftw

Reply #14February 17, 2008, 10:14:18 am

tSoG-84bit

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need some gear box advice
« Reply #14 on: February 17, 2008, 10:14:18 am »
4A tranny is the longest ratio 4 speed.
It's pretty long, almost too long for a stock engine, and I did a lot of driving around in 3rd, but I still had the ooomph to get out and do 80mph on the flat highways. I'd take a 4A over a lot of 5 speeds.

http://www.scirocco.org/gears/
final speed on 165-45-13 tires at 6000rpm for comparison----MPH
4A (1984 Deisel Rabbit only))-3.94--3.45--1.75--1.06--0.70---121
GP (3+E from '81) -------------3.89--3.45--1.75--1.06 -0.71---121
GY (3+E 8/82-7/84)------------4.17--3.45--1.75--1.06--0.71---113
GC (to '80)----------------------3.89--3.45--1.94--1.29--0.97---89
GC (from '81) ------------------3.89--3.45--1.94--1.29--0.91---95

if you do the math, the 4A is only slightly longer than the GP, but not enough to affect the 6000rpm speed on 165-45-13s
84bit 1.6na
Engine died, pulling it apart, putting something new in it's place.