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Diesel Cabriolet in the works by VWdieseljunkie on 27 Mar, 2010 10:10
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Well, the time has finally come. My 1986 Diesel Jetta Coupe has been retired due to the "New England Cancer". I found a cancer-free 1988 Cabriolet (CIS-e Jetronic) that is not running. Looks like it's swap time.
After looking at http://www.4crawler.com/Diesel/VW_020_transmission.shtml and comparing the transmissions, I see that everything is direct swap. I worry though what the different ratios are going to do to drivablility. Hopefully I can overcome the differences with tire size.
ACH= 210mm clutch, 100mm hub, 3.94 final drive, .75 fifth - diesel jetta
ACD= 210mm clutch, 100mm hub, 3.67 final drive, .89 fifth - gas cabby
I'm going to do a direct swap, keeping the diesel as stock as possible at first. This way, I can report the effects of modifications as I do them. The jetta is a non-a/c car so I'll delete the a/c from the cabrio (why keep it, it's a drop top). I am going to try to retain the power steering on the cabby, though. The biggest improvement to be gained in this swap should be power to weight ratio. If I understand correctly, the jetta is around 2700lbs, yet the cabby is around 2300lbs. Once the A/C components are deleted, along with the abused leather seating, It should be significant.
Once it is fully functional, and the bugs are all worked out, I would like to find a turbo and manifolds to add on, while retaining the non-enrichment IP.
Now to work out how much of the cabby is mk1, and how much is mk2. -
#1 by VWdieseljunkie on 28 Mar, 2010 08:32
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After reading as many posts as I could find on the web about using a close ratio trans on the diesel, I am rethinking using this ACD cabby trans. Problem is, reverse is toast in the ACH. I spent a while reading on how to change the reverse gear over at BROKEVW, and don't get the warm fuzzy feeling that this is something I want to tackle without adult supervision. The ACH has all the gears in all the right places for the n/a diesel. No doubt the ACD will bring the SUCK from a dead stop in first gear.
I guess it's time to start walking the boneyards looking for another alternative. -
#2 by theman53 on 28 Mar, 2010 09:04
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www.brokevw.com
http://www.qualityvwparts.com/
http://www.scirocco.org/gears/
Here is some sites that have info that you may or may not already know. I would think you would want a something like the AGS, ACN, or ACH. Good luck and I hope this helps. -
#3 by stewardc on 28 Mar, 2010 12:53
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Put the ACH 5th gear in the ACD. It's relatively easy. Then you'll have a great diesel tranny.
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#4 by VWdieseljunkie on 28 Mar, 2010 17:14
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Put the ACH 5th gear in the ACD. It's relatively easy. Then you'll have a great diesel tranny.
Really? If so, then this shouldn't be too bad! I wonder though what the car will drive like overall.
Using the ratios listed on 4crawler.com (scirocco.org doesn't list ACD ratios)
The ACH compared to the ACD is:
1st 2nd 3rd 4th 5th Final
3.45 1.94 1.37 1.03 .75 3.94 ACH
3.45 2.12 1.44 1.13 .89 3.67 ACD
With 185/60-14's at 3500rpm the mph would read:
1st 2nd 3rd 4th 5th
17 30 43 58 80 ACH
18 30 44 57 72 ACD or 86 w/.75 from ACH.
Is that going to be too wide of a gap between 4th and 5th? Then again, only 1mph difference between the 4th gears, so I guess it doesn't so much matter. Atleast 5th gear should be in good shape in my ACH. I looked over the 5th gear procedures on brokevw.com, it looks like something I should be able to handle. Worse case scenario, I won't touch the ACD until after removing 5th from the ACH. That should better guage how confident I feel on tearing into the ACD.
The little 1.6n/a is very lively in the jetta, almost sporty, with a top end allllmost holding 90mph. Once in the cabby with the ACD, maybe the weight difference will make up for the difference in gearing.
With the two cars side by side, comparing the differences in the engine bay, I am reminded that the cabby is nothing more than a mk1 rabbit. Been a few years since my last one, in 2001 before I shipped out for my tour in the sand box. For some reason I had it in my head that the motor in the cabby would drop out the bottom with the "sub-frame" like the jetta will. Oh yeah, there isn't one in the cabby! That epiphany came right after the thought of "how the hell does the core support come out?!?
It had better work out to make a good driving little car. If it doesn't, then I may end up just making a 4x4 play toy out of it. Does this give any impression of what monstrosity I might build? (tractor not included)
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#5 by lovinthedeez on 28 Mar, 2010 17:24
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an 86 is a mk2
the cabriolet, no matter what the year, is mk1
mk1 no subframe
mk2 subframe
seems like you have enough access to the right tools. get the motor out of the jetta, put it somewhere. lift the cabby over the motor. lift up motor. done
you're still going to need the injection pump bracket for the mk1. the mk2 motor mount attaches to the back of the block, whereas the mk1 passenger side motor mount is part of the injection pump bracket
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#6 by VWdieseljunkie on 28 Mar, 2010 18:38
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you're still going to need the injection pump bracket for the mk1. the mk2 motor mount attaches to the back of the block, whereas the mk1 passenger side motor mount is part of the injection pump bracket
Aw man, don't tell me that! Maybe I've still got an old junk diesel rabbit block sitting around that has what you speak of. Assuming it didn't take a trip to the scrap yard when auto scrap went over $13/100 a few years ago. Shouldn't be too hard to find though. You've definitely giving me something to look at that I hadn't realized yet! -
#7 by lovinthedeez on 28 Mar, 2010 20:11
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worse comes to worse, ebay always has them. its nothing to get shook up over. when converting to diesel, there's always a little list to do.
other things you're gonna have to do
removing all the old wiring from the engine bay
figure out a glow plug system
remove the fuel pumps from the gasser and installing new lines to the fuel filter(use all the jetta stuff)
run 12v while cranking to the ip
remove the diesel nozzle restrictor at the fuel filler neck
have fun while doing it (cuz thats the point right?)
just take yer time........here's my conversion. Its the reverse of what you're doing. the only difference is our pass side motor mount. almost everything else will be the same. good luck
http://www.vwdiesel.net/forum/index.php?topic=19324.0 -
#8 by gldgti on 29 Mar, 2010 01:06
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i have a 91 (ex-digifant) cabriolet that the PO converted to diesel before I bought it from him. Did nothing to the fuel lines other than connect them to the IP and fill the tank with diesel..... runs fine with the n/a 1.5 in it :-)
dont know if the CIS pump will allow fuel through like the digi one clearly does though. -
#9 by overdrivegear on 30 Mar, 2010 12:33
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i have a 91 (ex-digifant) cabriolet that the PO converted to diesel before I bought it from him. Did nothing to the fuel lines other than connect them to the IP and fill the tank with diesel..... runs fine with the n/a 1.5 in it :-)
dont know if the CIS pump will allow fuel through like the digi one clearly does though.
I'm building a 1.6 NA Cabriolet with a ME hydraulic head engine and AGS out of an 86 Jetta. The transmission has a 0.71 fifth gear that I added (just like on my ACH Golf) and it's amazing. Most people say that the 1.6 NA doesn't have enough guts to pull that gear but a buddy of mine has a 9A close ratio trans with a 0.71 fifth so it has excellent acceleration through 4th and when you drop it into 5th, it's a super interstate cruiser! Best of both worlds.
I've wondered about the CIS fuel pump myself. I'm going to leave the in tank transfer pump but yank out the high pressure one.
Check out my build! http://www.vwdiesel.net/forum/index.php?topic=24760.0 -
#10 by 8v-of-fury on 31 Mar, 2010 17:36
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The transmission has a 0.71 fifth gear that I added (just like on my ACH Golf) and it's amazing. Most people say that the 1.6 NA doesn't have enough guts to pull that gear.
I agree, I have a 81 1.6 NA with a FF (3.89 final and 0.71 5th) trans and it still has some fairly good pull in 5th, and this is on a bone stocker too. People are a little undercutting the little 1.6 N/a's I feel. Mine has considerable power for not one mod done to it. -
#11 by VWdieseljunkie on 02 Apr, 2010 18:10
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Check out my build! http://www.vwdiesel.net/forum/index.php?topic=24760.0
That was one of the first builds my search yielded. Have you had the chance to drive it yet?
I'm going to go ahead and try to make the gasser run, if nothing else to at least get a feel for the transmission that's in it, and what ever other issues the little cabby might have that isn't jumping out at me. I figure that the best bet is to simply grab a high pressure pump and drop it in a fuel can, completely bypassing the cabby's existing rank fuel system. It's been sitting for at least two years. If the motor will run, I may have a use for it later if I can find an auto trans, but that's neither here nor there.
I'll finally have time to hit the local boneyard this weekend to see what I can find. It's really hit-or-miss in the south when it comes to volkswagens. -
#12 by VWdieseljunkie on 03 Apr, 2010 17:20
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you're still going to need the injection pump bracket for the mk1.
Stupid bracket has me bummed out. I have one off of an old 1.5 block, but needs a new mount pressed in. On top of that, the jetta has less than 10k on it since last timing belt change, and I SO do not wan't to mess with the pump to get the current bracket off. It's timing is perfect. Sux because the jetta has officially been deemed UN-roadworthy, while looking at stuff, I noticed the brake line that runs from the master cyl, across the firewall to the pass wheel, has erupted due to rust. Now I have two turds in my front yard, lol! -
#13 by lovinthedeez on 03 Apr, 2010 21:40
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Isn't any way that motor is going in that car without more time and effort. spend the money to get a nice new hd mount pressed in. the timing isn't that hard, and if you plan on running it for a long time, you're gonna have to learn sooner or later.
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#14 by VWdieseljunkie on 04 Apr, 2010 07:48
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Isn't any way that motor is going in that car without more time and effort.
Oh there's no doubt about that. It's the "wish in one hand and $h!t in the other" routine that I'm stuck on. The little hard parts that you can't buy at a parts store are gonna drive me nuts, but I knew that, too. Been doing this since 1990, I guess I just p!ss and moan about it more with age.