5th gear upgrade. .681 success 11% RPM drop

[mycruiseagent]

I have a suggestion for the procedure and for ongoing maintenance. I was one of the very early adopters of this mod (January of 2006) and have enjoyed it very much.

However in July of 2012 (after a little less than 100,000 miles) I nearly had a catastrophic failure. The center bolt on the large gear backed out and the synchronizer hub came in contact with the transmission end cover. The outer ring of the hub assembly wore through the cover while everything continued to function (the ring stayed in contact with the inner hub). The catches and their retainer springs were destroyed in the process.

I purchased a new hub assembly and synchro and put the whole thing back together ... running it for a short while with fresh lube, then dumping it and replacing the fluid to be sure I got any metal particles out from the damaged end cover.

david_594 and I did the original install of these gears back in 2006, so I'm pretty sure we followed his guidelines for torque. Given my experience, I'm not so sure that the 59 ft-lbs called out in the procedure is sufficient to flat load the Bellville disc spring.

At the very least I would recommend that people who have done this mod change their transmission lube at something like 75-80K and take the time to pull the end cover and check the torque on the large bolts.

MCA

 

[MikeMars]

...
david_594 and I did the original install of these gears back in 2006, so I'm pretty sure we followed his guidelines for torque. Given my experience, I'm not so sure that the 59 ft-lbs called out in the procedure is sufficient to flat load the Bellville disc spring.
...

I don't know about the 5th gear mod, but the 6th-gear kit instructions suggest
a) loctite, and also
b) torqued up to 120NM (= 88 ft-lbs)
for this bolt (steps 19-21 in their instructions).

When Vince was installing mine I was surprised at how much effort that much torque required!! I would imagine that you could do the same on the 5th gear mod.


Vince likes to change the transmission fluid at the same time as doing the cambelt. I ended up changing my tx fluid 3 times last year LOL (first at the cambelt, 2nd when the 6th gear was installed, and thirdly when he was investigating an issue with the end-float).


Incidentally, were there any warning signs that the bolt was touching the transmission case? (for example, noises or excess heat?)

 

[mycruiseagent]

I don't know about the 5th gear mod, but the 6th-gear kit instructions suggest
a) loctite, and also
b) torqued up to 120NM (= 88 ft-lbs)
for this bolt (steps 19-21 in their instructions).

I'd guess this is about right - I did 90 ft-lb when I put it back together today (just taking a guess at a round number). The bolt is a M10x1.0 10.9 grade. Looking at torque specs for that grade bolt on the net that number seemed reasonable. The Bellville spring makes things a bit more difficult to figure out as it has to be loaded until it's flat to hold properly.

Incidentally, were there any warning signs that the bolt was touching the transmission case? (for example, noises or excess heat?)

It popped out of 5th gear once or twice on me, but no noticeable noise. When I got it home it was dripping trans lube.

 

[TDIJetta99]

I typically use locktite and somewhere around 90 ft-lb when assembling them.. so far so good..

 

[Kevinski4]

I had an '04 Jetta Wagon come in that had lost 5th gear. Pulled the cover off and the small gear had walked off after the bolt loosened. This was a stock 5th gear on an untouched transmission with 95k on it.

So if a factory assembled 5th can come off on its own, somebody’s .681 coming off may not necessarily be a result of improper assembly.

 

[mac11]

I had an '04 Jetta Wagon come in that had lost 5th gear. Pulled the cover off and the small gear had walked off after the bolt loosened. This was a stock 5th gear on an untouched transmission with 95k on it.

So if a factory assembled 5th can come off on its own, somebody’s .681 coming off may not necessarily be a result of improper assembly.

Or both were possibly under torqued?

 

[mycruiseagent]

Took it for a drive to Atlanta this weekend ... all worked fine. I've got some other issues to take care of on a 12 year old car but perhaps that's the last time I need to open up the transmission!

 

[touaregv10tdi]

I need a set of taller gears for my 1996 Golf GTi VR6 something like .681 5th gear set.
From 93-2003 Transporter Synchro
I need it bad
weldas@msn.com

 

[silentdub]

This thread offered some interesting reading for sure.

I've seen a lot of posts about the .717 and .681 but not much about the others. I found a place that sells the following for the 02J:.592 .622, .658 .681 & .717

 

[Hyde7278]

This thread offered some interesting reading for sure.

I've seen a lot of posts about the .717 and .681 but not much about the others. I found a place that sells the following for the 02J:.592 .622, .658 .681 & .717

Can you post where you found them?

 

[Rembrant]

Can you post where you found them?

That looks like the exact list of gear sets from Darkside Developments...and while they're still listed on the website, some of those gear ratios are no longer available and haven't been for quite a while.

http://www.darksidedevelopments.co....2c-02z-592-622-658-681-717-5th-gear-sets.html

Unless somebody started producing them again, the .681 gears have been NLA for quite some time...not sure what others.

 

[silentdub]

That looks like the exact list of gear sets from Darkside Developments...and while they're still listed on the website, some of those gear ratios are no longer available and haven't been for quite a while.

http://www.darksidedevelopments.co....2c-02z-592-622-658-681-717-5th-gear-sets.html

Unless somebody started producing them again, the .681 gears have been NLA for quite some time...not sure what others.

That would be them.

 

[dan30thz28]

I have the .658 and I love it! I haven't had a tank with less than 50mpg, and with the stage 2 tune and injectors it's like I have the best of both worlds!

 

[kwong7]

After sitting on the shelf for nearly 10 years, I finally had my .681 gear set installed when I had my Peloquin and clutch installed. I love the rev drop in top gear and it makes driving between 70-80mph quite a bit quieter. I've only seen a very small increase in fuel economy (and extra 10-20 miles per tank), but I've noticed that I've been driving about 5-10% faster as a cruising speed…75MPH is my new 70.

 

[david_594]

Its been nearly 10 years since I first posted this thread and I'm still quite happy with this modification.

My car is moderately tuned, but I can never remember a time that I've felt the jump from 4th to 5th was too great after this modification.

I still feel like my jetta is one of the nicest highway cruisers you can drive and it still returns a consistent 54 mpg with the cruise set at an actual 70 mph.

 

[kwong7]

Its been nearly 10 years since I first posted this thread and I'm still quite happy with this modification.

My car is moderately tuned, but I can never remember a time that I've felt the jump from 4th to 5th was too great after this modification.

I still feel like my jetta is one of the nicest highway cruisers you can drive and it still returns a consistent 54 mpg with the cruise set at an actual 70 mph.

After driving with the .681 gear set for about 2 months now, I comfortable the following shift points from 4th-5th:

Cruising - 48mph with the RPMs just below 1,600 for zero acceleration
Slow acceleration - 55mph with the RPMs right at 1,800
Moderate-fast acceleration - >60mph.

I'm essentially shifting into 5th at 11% higher on the speedometer depending on my acceleration needs.

 

[mxracer291]

Would love to buy a used .681 set!

Sent from my LGLS991 using Tapatalk

 

[deejaaa]

.......found a place that sells the following for the 02J:.592 .622, .658 .681 & .717

...exact list of gear sets from Darkside Developments.... are no longer available and haven't been for quite a while.

http://www.darksidedevelopments.co....2c-02z-592-622-658-681-717-5th-gear-sets.html
...... the .681 gears have been NLA for quite some time...not sure what others.

That would be them.

good thing you researched this first before posting false information. this is what makes this site so great.

 

[DieselCecil]

Are the parts available to do this to an automatic too? I have a 2002 golf.

 

[deejaaa]

Are the parts available to do this to an automatic too? I have a 2002 golf.

ehhhhhh.....no! especially no mavericks.

 

[Boostedballs]

I am planning this mod for the near future as I drive highway for 105 miles a day at 82mph. I usually get around 42mpg but I think my timing belt was a tooth off. I have a new timing belt kit installed but the damn DMF seems to be on the way out so the car is parked until I replace the whole clutch kit, which arrives today.

Should I go with the tallest possible 5th gear set?
Also, what gear oil nets the best MPG without increased wear?

 

[boertje]

I did a 5th gear swap years ago using the 0.681. I found this about perfect although there was just a little to much difference between 4 and 5 and if you go even taller, that difference will be that much more.

 

[Fix_Until_Broke]

I am planning this mod for the near future as I drive highway for 105 miles a day at 82mph. I usually get around 42mpg but I think my timing belt was a tooth off. I have a new timing belt kit installed but the damn DMF seems to be on the way out so the car is parked until I replace the whole clutch kit, which arrives today.
Should I go with the tallest possible 5th gear set?
Also, what gear oil nets the best MPG without increased wear?

I'd go with the tallest one you can fine (0.622 maybe?) since you spend so much time at speed. Yes, there will be a bigger gap between 4th and 5th, however for the few times a day that you do this shift, I wouldn't be bothered by it.

You can also go with a slightly taller tire (205/70/15) when it's time to replace them for another slight RPM reduction.

I would recommend VW G070 for the transmission and a 0w30 diesel oil for the engine.

 

[john.jackson9213]

As FUB says, the .622 5th gear may be the best choice for your drive.

I ran the .622 5th for about 18 months and did not find it too bad at all. The best thing about it was the engine noise reduction at highway speeds. Fuel economy improved by about 5%.

For the last 5 years plus, I have been running with the EuroTuning.cz 6 speed conversion kit and 195/65 x 15 tires.

 

[ke6iyc]

Good Morning.

New TDI owner here (2000 Jetta manual)

Reading through this monster thread, and it raises a couple of questions.

My car, at 2000 RPM (indicated) is going 60 MPH (indicated) which, if accurate, indicates a stock 0.756 5th with a 3.156 final drive.

2 questions now beg for answers.

Was this configuration ever a factory option?

Does anyone on this board (who might read this thread) know of a dark blue 2000 jetta from Austin, previously owned by a Lesley Williamson?

I will be confirming speedometer readings by GPS tonight.

Would like any input on this.

Thank you!

 

[IndigoBlueWagon]

I think your speedometer reads a bit high. You may also want to check your tire size. Whatever wheel size you have, stock tire diameter is 25".

 

[ke6iyc]

After checking with a GPS, yes, the speedometer is off.

But not by a consistent amount.

Thank You!

Brian

 

[Houpty GT]

After checking with a GPS, yes, the speedometer is off.

But not by a consistent amount.

Thank You!

Brian

A consistent amount means the needle was put on wrong. If it is off by a constant percentage then it is gears or tires. Maybe some other incorrectly replaced part.

 

[jetta 97]

If anyone looking for .681 gear set I have one for sale:

FS: VW 5th gear .681

I Have 5th gear .681 for sale . This gear is no longer available and this was most popular gear for upgrade. The .681 will drop RPMs by approximately 300-400 rpm, depending on wheel and tire sizes. This is original VW gears and you can conform here that is .681 Gear set here at Kerma by part...

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