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Close ratio trans with a diesel?
by
hamradio
on 17 Mar, 2010 10:22
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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.
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#1
by
truckinwagen
on 17 Mar, 2010 10:25
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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.
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#2
by
hamradio
on 17 Mar, 2010 11:44
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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.
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#3
by
rabbitman
on 17 Mar, 2010 11:52
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I'm sure you've seen this,
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.
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#4
by
hamradio
on 17 Mar, 2010 12:20
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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.
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#5
by
Rabbit on Roids
on 17 Mar, 2010 20:40
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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.
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#6
by
NintendoKD
on 17 Mar, 2010 22:37
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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
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#7
by
Rabbit on Roids
on 18 Mar, 2010 07:20
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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...
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#8
by
JerryGTD
on 18 Mar, 2010 10:13
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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
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#9
by
NintendoKD
on 18 Mar, 2010 19:26
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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.
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#10
by
Rabbit on Roids
on 19 Mar, 2010 06:57
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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
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.
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#11
by
JerryGTD
on 19 Mar, 2010 07:28
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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.
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#12
by
8v-of-fury
on 19 Mar, 2010 11:16
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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
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#13
by
JerryGTD
on 19 Mar, 2010 11:47
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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.
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#14
by
Rabbit on Roids
on 19 Mar, 2010 20:24
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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.