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020 AUG 5th gear swap question
by
christoferus
on 02 Jun, 2015 14:33
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Hello, I have an AUG tranny that turns 3000 rpm at 90 kph making it terrible for highway cruising. I also have a 7A tranny which is geared a bit taller and has a 0.71 fifth gear. I plan to replace the 0.89 fifth in the AUG with the 0.71 in the 7A pairing the taller fifth with the AUG's 3.67 final drive. Now I will be able to go 90 kph spinning 2158. This modified AUG is going on a 1.6td, with a brand new 1.9 head, port and polished arp head studs k24 turbo and fully rebuilt frankenmotor.
My question: Ive been using Scirrocco.org gears to calculate my speed and rpm, so if I am going 100kph in 4th at 3800 and I shift to 5th going the same speed my rpm will drop to 2393. Is this rpm drop too large? Will this be like shifting from 2nd to 5th normally? I have read that people that do this in a stock 1.6 td will have power issues on hills and headwinds, but with my frankenengine, my thought is that she'll have enough gut to power the tall 5th and make cruising efficient.
Cheers,
Chris
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#1
by
theman53
on 02 Jun, 2015 23:34
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I think you will effectively have a 4 speed with an insane overdrive. The ratio is fine if your 1.6 makes power, but the gap is just too large. I don't know what it is going into, but the 7a would be a much better trans IMHO.
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#2
by
christoferus
on 03 Jun, 2015 01:07
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Thanks for responding Theman53! The trans and frankenengine is going into a '90 mkII jetta coupe. I think I may use the 7a instead.
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#3
by
christoferus
on 03 Jun, 2015 01:25
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#4
by
theman53
on 03 Jun, 2015 11:24
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The 7a IIRC came out of an MKI if it did you will have to drill some holes to mount it into an MKII. I would much rather have a 7a, especially if the engine is making power the short gears are dumb.
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#5
by
christoferus
on 04 Jun, 2015 01:50
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Yeah the short gears are a pretty massive pain
as for the mounting, it seems this 7a has the bracket and bolt holes for the mk2 mounting, came out of a early mk2 golf IIRC.
currently what it looks like
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#6
by
theman53
on 04 Jun, 2015 10:13
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Then I would just bolt it in. I have an ags with a 3.67 R&P and still wish I had more gear. When you add power to these I don't personally think it is fun to shift out of a gear in less than .5 second.
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#7
by
christoferus
on 04 Jun, 2015 13:00
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Did you change the R&P on the Ags? Do you have to change the pinion shaft aswell?, I was thinking of trying something like that cause the 7a R&P is 3.94. AGS came in a 1.6 eh? Hopefully this 7a has some decent passing power, in the future I'm aiming at a 02A or 02J swap but in the meantime this will do just fine. Plus these 020's are easy to work on.
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#8
by
theman53
on 04 Jun, 2015 23:38
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Looks like the clutch cable is stronger than your case
The R&P is the ring and pinion, so yes you have to change the pinion gear, not the main shaft. I had brokevw do mine and it is cryo treated, if you are going to the better trans in the future it is pointless to put more time into an 020. I would be more worried to know how good the 7a is. Watch the oil as you drain it and clean it out good before install.
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#9
by
christoferus
on 05 Jun, 2015 01:46
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Haha yeah there is usually bushing in there that prevents that case chewing, whoever installed the clutch cable before left them out.
I'm getting an aluminum weld for that tomorrow, then grinding it flush. Also there is a chunk broken off where one of the mount bolts go into the diff housing on the case. I am getting that welded as well. Yeah im going to make it all nice and clean, flush the tranny with ATF before its mounted and using Amsoil 75-90 synthetic gear oil.
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#10
by
Dakotakid
on 05 Jun, 2015 21:56
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Clearly, this 7A has been "around" for quite awhile.
If it were ME, I would not consider installing it until I had removed and replaced:
1) the little push rod blue seal
2) the corresponding (to the seal above) push rod bushing (located at the tip of the input shaft....stabilizes the push rod)
3) the larger input shaft seal.
NOW is the time to do these....now....not after your clutch is contaminated from gear lube.
And, I would never install without replacing the output shaft seals behind the output flanges for task #4.
But, that is just me...and I been around for a while.
And, yes, you will need a tool to compress the flanges. But, it is much easier now that later while you lay under the car.
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#11
by
christoferus
on 06 Jun, 2015 20:36
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Yeah thanks for the advice, I am in the process the things you mentioned at the moment, replacing all seals and any circlips I take off as well as the O-ring on the backside of the selector housing. I do have the puller tool for the flanges. Thanks again for the tips
