VWDiesel.net The IDI, TDI, and mTDI source.

Engine Specific Info and Questions => IDI Engine => Topic started by: hamradio on March 17, 2010, 10:22:43 am

Title: Close ratio trans with a diesel?
Post by: hamradio on March 17, 2010, 10:22:43 am
So,

I impulse bought myself a 4k GTI trans for $25.  Right now my diesel has an FN in it.

I'm currently running a VNT15 at 25 psi and don't like how tall second is.  The last time I autocrossed it, I would experience loads of lag out of corners in 2nd...it wasn't worth downshifting into first for the few hundred rpm I could get out of it at that speed.  My fear is, though, that the limited rev range of the diesel (mine maxes out at about 5500) would not work well with that transmission.


Any thoughts?

I'm probably going to be ditching the VNT15 in favor of a T3 within a few weeks, as well.
Title: Re: Close ratio trans with a diesel?
Post by: truckinwagen on March 17, 2010, 10:25:26 am
you will be fine, you just run out of speed with it.

I have a close ratio GTI box on mine, and it only revs to 4000.

it is fun to shoot around town, but is death on the highway.
Title: Re: Close ratio trans with a diesel?
Post by: hamradio on March 17, 2010, 11:44:49 am
Aight, rad.  I don't really mind if I 'run out of speed'...I don't think I've ever taken the car above 90 anyway, and it felt sketchy at that speed.

I suppose if I really dislike this gearbox, I can always just swap back to my FN in a saturday morning.
Title: Re: Close ratio trans with a diesel?
Post by: rabbitman on March 17, 2010, 11:52:23 am
I'm sure you've seen this, http://www.scirocco.org/gears/ (http://www.scirocco.org/gears/)

I wouldn't think the tiny 2nd gear gain would be worth the loss of top end.

EDIT: Never mind, I was forgetting to change the final ratio too. So 2nd would be pretty good but at 5500rpm/5th you'd lose about 25 mph.
Title: Re: Close ratio trans with a diesel?
Post by: hamradio on March 17, 2010, 12:20:26 pm
Yep, I was playing around with the scirocco.org calculator.


I just can't figure out if the limited to end revs would drive me nuts with this trans or not.  A friend used to have a beater rabbit GTI with a 1.8 8v and 4k in it, and I had a riot driving that car around.  I loved the gearing.
Title: Re: Close ratio trans with a diesel?
Post by: Rabbit on Roids on March 17, 2010, 08:40:56 pm
i had an aug in my rabbit with my 1.5, and it liked the close gears just fine, but i pretty much dont really have a governor. so i can really rev my engine out and use the short gears.
Title: Re: Close ratio trans with a diesel?
Post by: NintendoKD on March 17, 2010, 10:37:14 pm
you didn't by chance get this idea from me did you? ;) not that it matters, but I'm thinking that this will be awesome in my spyder, a little over two tons with a topped out 1.6 with an aaz head and about 35 pounds of boost.  The only thing that does concern me, is that I do want to take trips, is there a way to put a tall final gear in so that I can do that?  I don't want to say it, but I want to have my cake and eat it too. ::)  FF .71 final any good for this?
Kevin
Title: Re: Close ratio trans with a diesel?
Post by: Rabbit on Roids on March 18, 2010, 07:20:19 am
you didn't by chance get this idea from me did you? ;) not that it matters, but I'm thinking that this will be awesome in my spyder, a little over two tons with a topped out 1.6 with an aaz head and about 35 pounds of boost.  The only thing that does concern me, is that I do want to take trips, is there a way to put a tall final gear in so that I can do that?  I don't want to say it, but I want to have my cake and eat it too. ::)  FF .71 final any good for this?
Kevin

the gears are too wide in the FF. ACN is good for what you want to do. i have one in my car. 3k @70 mph. the first 4 gears are spaced pretty nice for a diesel, then you grab fifth and just cruise.

and how on this earth does an MR2 weigh over 4000 pounds? my 89 4runner weighs about 2 tons. there is no way your mr2 spider weighs 4000 lbs...
Title: Re: Close ratio trans with a diesel?
Post by: JerryGTD on March 18, 2010, 10:13:13 am
Since you already have the 4K, you might as well just put it in and try it out. The hot ticket might be to install the .71 5th gear from the FF. You could do this while it is in the car or out. However the 4th to 5th shift into hyper drive may be problematic because of the big drop in RPM. In that case you could use a .75 5th for a difference of approximatley 200 RPM.

I am running the stock AVX trans with 4.25 final in my 91 Jetta ECOdiesel and it is way fun to drive around town. The gear ratios are the same as an AGS but with a different final. The AGS is 3.94.  The AVX has a .75 5th but could definitely use a .71 5th even though it would only drop the RPMs by about 200. My car is not a great highway cruiser with the AVX as it is right now.

I have a junk ACH with a .75 5th that I need to dismantle and may have a line on a 4 speed from a Rabbit that has a .71 4th that I can pirate.

Good info on ratios is here:
http://www.a2resource.com/eandt/ratios.html (http://www.a2resource.com/eandt/ratios.html)
Title: Re: Close ratio trans with a diesel?
Post by: NintendoKD on March 18, 2010, 07:26:38 pm
you didn't by chance get this idea from me did you? ;) not that it matters, but I'm thinking that this will be awesome in my spyder, a little over two tons with a topped out 1.6 with an aaz head and about 35 pounds of boost.  The only thing that does concern me, is that I do want to take trips, is there a way to put a tall final gear in so that I can do that?  I don't want to say it, but I want to have my cake and eat it too. ::)  FF .71 final any good for this?
Kevin

the gears are too wide in the FF. ACN is good for what you want to do. i have one in my car. 3k @70 mph. the first 4 gears are spaced pretty nice for a diesel, then you grab fifth and just cruise.

and how on this earth does an MR2 weigh over 4000 pounds? my 89 4runner weighs about 2 tons. there is no way your mr2 spider weighs 4000 lbs...

sorry, I said two tones, but it is a little over 2000 pounds, typo, thinking one thig and posted something entirely different, there is a lot going on up there nowadays.
Title: Re: Close ratio trans with a diesel?
Post by: Rabbit on Roids on March 19, 2010, 06:57:00 am
Since you already have the 4K, you might as well just put it in and try it out. The hot ticket might be to install the .71 5th gear from the FF. You could do this while it is in the car or out. However the 4th to 5th shift into hyper drive may be problematic because of the big drop in RPM. In that case you could use a .75 5th for a difference of approximatley 200 RPM.

I am running the stock AVX trans with 4.25 final in my 91 Jetta ECOdiesel and it is way fun to drive around town. The gear ratios are the same as an AGS but with a different final. The AGS is 3.94.  The AVX has a .75 5th but could definitely use a .71 5th even though it would only drop the RPMs by about 200. My car is not a great highway cruiser with the AVX as it is right now.

I have a junk ACH with a .75 5th that I need to dismantle and may have a line on a 4 speed from a Rabbit that has a .71 5th that I can pirate.

Good info on ratios is here:
http://www.a2resource.com/eandt/ratios.html (http://www.a2resource.com/eandt/ratios.html)

4th gear out of a 4 speed wont work as fifth gear in a 5 speed. as 5th gear is outside the actual trans case. if you want to do something like that, just leave the 3+E alone and install it.

and kev, if you have a 4k trans, just run with it. once everything is in the mr2, it will be easy as swapping the trans out of a vw.
Title: Re: Close ratio trans with a diesel?
Post by: JerryGTD on March 19, 2010, 07:28:09 am
Quote
4th gear out of a 4 speed wont work as fifth gear in a 5 speed. as 5th gear is outside the actual trans case. if you want to do something like that, just leave the 3+E alone and install it.

Good information there ^.  However, the 3+E would be minus one gear and would not have a 4.25 final. Being that it is from and MK1, the fitment could be problematic in my MK2 Jetta. I'd rather find the proper .71 fifth gear. Likewise, the 200 RPM drop would be hardly noticeable so I'm in no rush to do it.
Title: Re: Close ratio trans with a diesel?
Post by: 8v-of-fury on March 19, 2010, 11:16:30 am
Your looking for a 4.25 final with a .71 5th?

thats not too bad, you'll cruise at 2600 rpm in 5th at 60 mph.

AND BE PEPPY AS ALL HELL THROUGH TOWN LOL
Title: Re: Close ratio trans with a diesel?
Post by: JerryGTD on March 19, 2010, 11:47:27 am
Your looking for a 4.25 final with a .71 5th?

thats not too bad, you'll cruise at 2600 rpm in 5th at 60 mph.

AND BE PEPPY AS ALL HELL THROUGH TOWN LOL

The car came stock with a 4.25 final and a .75 5th (AVX). So that is what is in there now.
It is a blast to drive around town. When highway cruising I am usually in the right hand lane trying to keep the revs down. Because .71 is the lowest 5th you can get for the 020, swapping that in place of my .75 would be the easiest solution. It is still alot of work for only a 200 RPM reduction. 
Title: Re: Close ratio trans with a diesel?
Post by: Rabbit on Roids on March 19, 2010, 08:24:18 pm
i would get rid of that junk AVX. i like running 3.67 final drives personally.

just sell the avx to some gasser boy on the whoretex. and buy yourself a real trans. ACN and AGS trans are both very good match to a diesel.
Title: Re: Close ratio trans with a diesel?
Post by: JerryGTD on March 21, 2010, 10:27:32 pm
i would get rid of that junk AVX. i like running 3.67 final drives personally.

just sell the avx to some gasser boy on the whoretex. and buy yourself a real trans. ACN and AGS trans are both very good match to a diesel.

Thanks for your priceless advice, but I want to keep my junk AVX.  I like the greater mechanical advantage of the 4.25 final. I am willing to sacrafice a few miles per gallon for better driveability. 90% of my driving is local stop light to stop light.





Title: Re: Close ratio trans with a diesel?
Post by: Rabbit on Roids on March 22, 2010, 05:45:56 am
thats fine. but i cant think of a worse way to set up a trans, have a nice super tall fifth gear, then negate that with a stupidly low final drive. ill tell you what, ive never had any problem with 3.67 gears in stop and go driving. i personally have never owned a AVX, but ive owned a couple trannys with with 3.94 finals in them, and the only benefit, was i had better engine braking going down hill. other than that, it just sucked. but i guess when you have enough power to use tall gears, then go for it. and i definitely have that power. an eco diesel is underpowered at best. a small turbo mixed with a tiny fuel pump. lol...
Title: Re: Close ratio trans with a diesel?
Post by: JerryGTD on March 22, 2010, 07:19:36 am
Quote
i personally have never owned a AVX

Thats fine. I never owned a gasser boy tranny with a 3.67 final.

Quote
an eco diesel is underpowered at best. a small turbo mixed with a tiny fuel pump. lol...

What are you doing here? ^ Trolling? lol Lets stick to the subject of transmissions.



Title: Re: Close ratio trans with a diesel?
Post by: 8v-of-fury on March 22, 2010, 12:20:21 pm
I dunno here guys, the difference between a 4.25 final w/0.71 5th and a 3.67 final w/0.71 5th is a mere 350 RPM at cruising speeds..

Even so the difference between a 3.94 and 4.25 is debatable.. Only 200 RPM difference between 2400 and 2600 RPM.

You say you bought a 4K! YES IMHO the best ratio trans for a power house engine! Take the .71 5th from the FN and swap it in to the 4K, yes the jump from 4th to 5th will be larger it will still be very doable.. and most delectable. Say you shift from 4th to 5th at 60mph at 3800 rpm.. its gonna drop you in to a cruising RPM of 2400 in 5th. As long as you don't drop to 4th at anything over 3500 in 5th I think you will be quite alright.

NOT TO MENTION HOW FUN THAT MONSTER WILL BE IN TOWN! 5th will only be a highway gear like it is meant to be. ;)

Good luck with this. Don't mind Rabbit on Roids.. :P

Title: Re: Close ratio trans with a diesel?
Post by: NintendoKD on March 22, 2010, 01:54:11 pm
what kind of power nos. are we talking here? how much Hp's can this tranny handle?  that is, before the tranny goes KABOOM!!! :o
Title: Re: Close ratio trans with a diesel?
Post by: rodpaslow on March 22, 2010, 02:01:54 pm
The last post kind of scares me.  I've been following this and I am going to start, hopefully this weekend, building 1.6 TD with new goodies (pistons, girdle, redone head,etc) will have a T3 boosting it in a 96 Golf with an 020 tranny.  I'm expecting to be getting 20 psi boost (limit it to that).  I don't know what kind of power that will produce - is the tranny able to handle it (3.667 ratio with a .75 5th)
Title: Re: Close ratio trans with a diesel?
Post by: 8v-of-fury on March 22, 2010, 06:28:24 pm
Smokey Eddy on this board is running a 1.6 stock bottom end with a 1.9 AAZ head, and a T3 boosting its heart out. The fuel is also maxed out. His 020 is holding up just fine for the last year. He romps on it regularly. PM him if you have any questions
Title: Re: Close ratio trans with a diesel?
Post by: Rabbit on Roids on March 22, 2010, 08:06:16 pm
So,

I impulse bought myself a 4k GTI trans for $25.  Right now my diesel has an FN in it.

I'm currently running a VNT15 at 25 psi and don't like how tall second is.  The last time I autocrossed it, I would experience loads of lag out of corners in 2nd...it wasn't worth downshifting into first for the few hundred rpm I could get out of it at that speed.  My fear is, though, that the limited rev range of the diesel (mine maxes out at about 5500) would not work well with that transmission.


Any thoughts?

I'm probably going to be ditching the VNT15 in favor of a T3 within a few weeks, as well.


It sounds like your VNT15 is knackered.  If you have a functional vane control and turbo then you should experience no perceptible lag in 2nd unless you have a huge intercooler and oversize intercooler tubing.  Even with oversize intercooler and tubing and with vanes fully open you will experience considerably more lag with a T3.

i have a VNT 17 with wide open vanes, and the only time it lags is right off the line. once its spooled, your good to go. just pulls and pulls. it doesnt even lag bad off the line.
Title: Re: Close ratio trans with a diesel?
Post by: Rabbit on Roids on March 22, 2010, 08:13:57 pm
sorry guys, i just hated my close ratio trans once i got a suitable trans with some spread out gears. i used to love my AUG, but then i got an ACN and my love shifted. and diesels have torque, they dont need low finals and close gears to keep them wound up like gassers need.

another thing, you guys all talk about swapping in a high fifth in a close ratio trans, not a good idea. the split between 4th and 5th is a bit long for my tastes in this ACN, and it has as tall of a 4th (.91) as some of the close ratio fifth (.89) gears. if you could take an AUG or something close ratio'd like that, and add a .71 fifth as a sixth gear, now we would have one ***in tranny.

to each their own tho. my opinion is just that, an opinion. i dont care either way who puts what trans in what car. but the longer gears work better with a diesel. and a huge jump from 4th to 5th is far from ideal.
Title: Re: Close ratio trans with a diesel?
Post by: vanbcguy on March 22, 2010, 09:23:06 pm
I've got one of the steepest trannies out there - CHD... On the highway it's great, but about 5% of my driving is above 80 km/h.  For the vast majority of the driving I do I'd way rather have a lower ratio trans.  Sure, I can comfortably run the car up to 150 km/h but where the heck do you get to do that?
Title: Re: Close ratio trans with a diesel?
Post by: gldgti on March 23, 2010, 01:08:13 am
I've got one of the steepest trannies out there - CHD... On the highway it's great, but about 5% of my driving is above 80 km/h.  For the vast majority of the driving I do I'd way rather have a lower ratio trans.  Sure, I can comfortably run the car up to 150 km/h but where the heck do you get to do that?

i also have the CHD - i do 90% hiway milage so its great, but around town with my T3 now its a POS (hoping to rectify this soon though, i think i have some lingering turbo issues). Anyway, with the T2 on the aaz all was fine because the car had mountains of low end torque - now thats mostly gone and the CHD isnt ideal anymore for around town.

as for top speed though..... hehehehe :-D

Also I wanted to mention that the later CHD/CHE trans from A3 diesels are very STRONG. Much better than the earlier 5 speeds. If you have big power aspirations, it might be worth looking into finding one.

The only other thing i would vouch about the CHD for is that it does have very nicely spaced gears, all the way form 1st to 5th. if your out on the open road or in the twisties, its a nice gearbox to drive :-)
Title: Re: Close ratio trans with a diesel?
Post by: NintendoKD on March 23, 2010, 05:08:13 am
I've got one of the steepest trannies out there - CHD... On the highway it's great, but about 5% of my driving is above 80 km/h.  For the vast majority of the driving I do I'd way rather have a lower ratio trans.  Sure, I can comfortably run the car up to 150 km/h but where the heck do you get to do that?

i also have the CHD - i do 90% hiway milage so its great, but around town with my T3 now its a POS (hoping to rectify this soon though, i think i have some lingering turbo issues). Anyway, with the T2 on the aaz all was fine because the car had mountains of low end torque - now thats mostly gone and the CHD isnt ideal anymore for around town.

as for top speed though..... hehehehe :-D

Also I wanted to mention that the later CHD/CHE trans from A3 diesels are very STRONG. Much better than the earlier 5 speeds. If you have big power aspirations, it might be worth looking into finding one.

The only other thing i would vouch about the CHD for is that it does have very nicely spaced gears, all the way form 1st to 5th. if your out on the open road or in the twisties, its a nice gearbox to drive :-)

Awesome, I need to find one of these then.  This post has been most informative and helpful.
Title: Re: Close ratio trans with a diesel?
Post by: Rabbit on Roids on March 23, 2010, 07:27:26 am
i think i have a CHE, but i think its off a ABA. are they still stronger trannies than regular 020's? i know this one has the big input shaft and stuff.
Title: Re: Close ratio trans with a diesel?
Post by: gldgti on March 24, 2010, 01:12:39 am
indeed rabbitonroids - the CHE is AFAIK the CHD with the only difference being the larger input shaft diameter. The CHD is found on the AAZ mk3 diesels (i guess is could have come on 1Y engined cars aswell) where the CHE came on later 16V cars.

In my (albeit limited) research of the trans ratios, I am fairly sure that the CHD and CHE have the same gears. I am however certain that the CHD/CHE are very tough.
Title: Re: Close ratio trans with a diesel?
Post by: Rabbit on Roids on March 24, 2010, 07:19:41 am
score... cause im pretty sure i got one. it for sure has a big input shaft.
Title: Re: Close ratio trans with a diesel?
Post by: fatmobile on March 24, 2010, 08:20:38 pm
Reverse is known to go out in those.
 Might be because of the extra power in the 2.0; 8 and 16V.
 Reverse was never a strong point of the 020 tranys.
Title: Re: Close ratio trans with a diesel?
Post by: NintendoKD on March 24, 2010, 08:50:49 pm
got an e-mail back from our esteemed colleague reads as followes:
Kevin --

Thanks for contacting me, I appreciate it!

The torque is what will kill the trans.... that and shocking loads to it like a clutch drop or grabbing the gears hard.... basically anything fun.

The 020 could be used, but how long it lasts depends on the driving style. The more you smoothly roll into the power, the longer it will live. Even then, once you start really putting the torque into it, the parts will start to fail simply due to the smaller size.

If you need something stronger with the same bolt pattern for the engine block, consider the 02A trans from a Corrado G60 or a Passat 16V and I believe the new 6-speed 02M trans will bolt up as well.

All of them will use a different clutch system than the 020, which is basically backwards compared to everything else out there, but I don't know what limits you have with the parts on this Spyder like the clutch and axles and so on.

If you did decide to use the 020, I would plan on a bolt kit for the diff at a minimum, and if possible, a LSD for it (which you might want anyway just for traction). That will remove the weakness in the diff, then I would also consider something like cryo treatment for the rest of the parts, to try to get every last bit of strength out of them you can.

So it is possible, but depending on how it is used and driven, I wouldn't expect it to last another 100K miles like it would in a stock VW due to the increased power input.

Let me know if you have any other questions, and thanks for your service, I appreciate my freedom!
Hopefully in the future I'll still be able to enjoy what Liberty I have left, rather than being stuck in a Socialist nightmare.... but I digress:)

Brian
Title: Re: Close ratio trans with a diesel?
Post by: Rabbit on Roids on March 25, 2010, 07:42:44 am
Reverse is known to go out in those.
 Might be because of the extra power in the 2.0; 8 and 16V.
 Reverse was never a strong point of the 020 tranys.

ive had 2 reverse gears go out on me, both in 8v trannies. and another one on its way out as we speak.
Title: Re: Close ratio trans with a diesel?
Post by: vanbcguy on March 25, 2010, 09:40:14 am
The most common cause of reverse failure on 020's is not coming to a complete stop before shifting in to reverse.  They just weren't designed for anything other than absolutely coming to a full stop before shifting.

Larger turbos actually help really well with keeping your 020 in one piece - one place where turbo lag is a good thing!
Title: Re: Close ratio trans with a diesel?
Post by: Rabbit on Roids on March 26, 2010, 07:24:54 am
The most common cause of reverse failure on 020's is not coming to a complete stop before shifting in to reverse.  They just weren't designed for anything other than absolutely coming to a full stop before shifting.

Larger turbos actually help really well with keeping your 020 in one piece - one place where turbo lag is a good thing!

im nice to my reverse gears. its just the previous owners of all my transmissions have beat the crap out of them. i always let my trans stop before i throw it in reverse.
Title: Re: Close ratio trans with a diesel?
Post by: 8v-of-fury on March 26, 2010, 07:35:32 am
same here, full stop for first and reverse. any sort of of rolling movement no matter how slow, with a 3.94fd 2nd is usable.