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Intermediate shaft modification for stroker 1.8

7K views 42 replies 4 participants last post by  LT1M21Stingray 
#1 · (Edited)
So the butcher has a 1.8 stroker on the back burner. Eventually the engine will be going in my wife's Cabriolet along with small boost turbo set up.

I've been collecting parts for some time and I've researched this intermediate shaft issue even longer. There are a few options out there but I did not like any of them. Although shaving the gear,, so it will miss #4 rod is the go to method on the stock 1.8 block, I've just have issues with the shaved gear and longevity. I understand, no one has had an issue, and I'm concerned about nothing.

I decided to slightly press the gear off the shaft and check to see if the distributor gear is still aligned. I have found it you move the gear just over 2mm, that will allow enough clearance for the rod to pass without any damage. The distributor gear alignment seems to be ok too. What I plan on doing is drilling the end of the shaft and tapping it to accept a bolt. I will make a 2mm shim and then press the gear back on. Once it's completed, I will install the bolt and large washer to keep things from coming loose. There is plenty of room for hardware to keep the gear attached.

It's in the mock up stage and ready to go back into the corner of the shop. I hope to have the engine completely disassembled so I can get the block bored next week. The way I do things, it will probably be 15 years before I finish this project. I seriously need to get back on the POS.

This is what the shaft looks like installed

The distributor gear alignment

And the shaft out of the block for a better look.


Anyway, more useless information for those that want 2 litres but do not want to go the ABA route.
 
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#2 ·
ah now that idea had crossed my mind. good plan with the spacer/bolt too. I was thinking about the thinned out gear wearing out, but that could be caused by a number of thing. misaligned dizzy/worn out or incorrectly fitted inner int shaft bearing( oil spray channel not lined up right). or even softening of the gear due to too much heat during machining.
 
#4 ·
I have a 75 ton press. So far, the press has always won. To answer your question, it pressed out fairly easy.

I've thought about this challenge for years and it was common practice to trim the gear. Now it's common practice to just throw a ABA at it. I cannot believe that with all the years that have gone by, someone else did not think about it. There may be problems before I'm done, but I do not see any coming my way with this shaft modification.
 
#5 ·
you're going to lose a little of the "gear mesh" width either way I suppose. it also comes down to oil pump pressure, as to how much strain the gears see. of course, if you use the aba shaft, you would need the dizzy drive gear to match it. which would mean opening up the dizzy hole, which could be tricky as it's at a funny angle in both directions.
 
#6 ·
I really do not believe I will be loosing a lot of gear mesh. I have not thoroughly checked it yet. I'm assuming most of the load is in the center. By moving the gear over, the load is still in the same spot but on a different portion of the gear. Without a doubt, the oil pump is a huge load on a tiny gear.

My research shows that people were removing 5mm of the gear. I'm only moving the gear 2.1mm and with some fine tuning, I suspect it will be only 2.0mm. The amount of freeplay did not change by moving the gear.

The ABA route would indeed cause for a larger distributor hole which would have to go to a machine shop. I suspect enlarging the hole incorrectly would cause gear meshing issues. I really did not want to go that route.

I understand the ABA route may be cheaper, but if you are going to rebuild an engine, I'm suspecting the costs are going to be the same or even cheaper. Certainly less things to convert [higher exhaust, breather issues].
 
#8 ·
Without a doubt. I tried with a mirror and I really could not see much.

I originally pressed the gear almost 5mm. I installed the shaft and with the freeze plug out of the block, I was able to press [hammer time] the gear till it was hitting the rod. Then I pressed the gear back a bit.
 
#10 ·
That's an interesting solution for that problem. :thumbup:

Here's my IS. Been running this for 13 years now. Driving this setup for over 100k miles with no issues.

 
#16 ·
The R rods are narrower [where the rod would hit the gear] compared to the JH rod. The R rods are overall wider. I will know eventually, but it looks like the R rod will not hit the gear.

Pictures will follow since I'm not making much sense.
 
#19 · (Edited)
It's a cheap build, so I have not decided on balancing the rotating assembly. I will balance what I can, but subletting what I can't is still undecided. I seriously doubt if my wife will get it above 4k rpm. That is why I was thinking of a stroker. A little bit more torque on the low end and a turbo to put a smile on your face. If anyone had driven a gas Mk1 automatic, they're terrible if you want to go. The only worst combination is a diesel automatic. You might as well get out and walk. It will be faster.


Both A and B measurements are the same. But the taper on the Golf R rod 'C' is much less than the squared off JH rod. This area is where the rod will hit the gear. By moving the gear about 2mm, the JH rod will clear. I believe the R rod may clear with the gear in the stock location. I have to take the head and piston out to confirm if I'm right or not.

I hope that explains what I was saying.
 
#23 ·
you could always use the JH rods with the aba pistons in the bored out block. you could probably get away with skimming the block 1.5-2 mm. I was considering building an 1847cc block with 2E pistons, and figured out that a 2mm block skim would have things just about right.
 
#24 ·
I could, but I already have the pistons, rods, and block. I do not want to go with a tall block. The plan is to use my German JH block, drill it for oil nozzles, and bore it to the 82.5mm pistons. I'm just in the mock up phase to confirm all of this works.

That was the reason to post another idea of the old school intermediate shaft gear problem. I do not believe the the old school method is even done anymore since the ABA is the favored path for a 2.0l option. I spent a boat load of time on this gear issue and darn near all the photos are gone on the internet.
 
#25 ·
scratch that last post. i'm thinking of the 1.8 crank, and you're using the 2 litre:facepalm:. you could probably use the aba pistons and JH rods. I think the 20mm and the 21mm small end bushes both have a 23mm outer diameter, so would be easy enough to match the pistons/rods together. of course the aba pistons would protrude slightly above the deck( think it's about 1.3mm)but that could be taken care of with a decompression head gasket. another option to consider anyway.
 
#26 ·
Maybe, but I will never know. I have EA888 pistons and the R rods and that is the plan. The pistons require a trapezoid small end rod.

As of now, there is no reason that combination will not work. I will need to enlarge the combustion chamber area to dial in the compression ratio. I'm thinking of 9ish. I've got the tools to do that easily, no subletting required.
 
#36 ·
a little of topic but, does the 1.8 piston skirt clear the counterweight of the 2 litre crank at bdc?
Yes, there is plenty of clearance between the crank and piston. The pistons come up 3.5mm over the top of the block at the quench area. Could you shave the stock pistons and use them? Probably, but there is not a lot of distance from the top ring and the top of the piston if you did. Then you would have to figure out how to get the compression down to a normal level.

I think it would be foolish to modify the stock 1.8 pistons when there are so many cheap OEM pistons that would work better.
 
#30 ·
I think it would, but the head is on and the piston hits the head before the skirt. My goal was to take the head off today but I had other plans including gluing my new tubular tires to to climbing wheels. Going on a 10k climb in a couple of weeks.
 
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