atc70 build thread

[Roby466]

Hi,
I have just joined the forum. My first post in New Member welcome area being done, I will start my build thread here.
The restoration will be quite simple, rolling chassis restoration at this time and simple cleaning of the engine for now. The engine and gearbox seem to be going well so I won't open them up yet.
The end game is not a showroom atc but one that looks good and that the kids can use. I also intend to make an attachment for a garden kart and take it to the track to cart around tires and tools between the pits and the paddocks.
I picked up the atc70 a little while back and this weekend is sandblasting weekend. I will do the chassis, axle tubes, front fork and all the steel that will see por15 protection and then top coat.
I will also take the wheels apart, and restore them before re-installing the new tires that are already there.
I am looking for a metal tank though. If anybody has one, let me know!
Pictures will come but here is what it looks like now.
Cheers
David



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[coolpool]

Hi David. It's a miracle you found one these days, nice! If you're not familiar with these things one very common ailment is a bent frame near the steering neck. It's easy to fix if yours suffered the same fate. Put a straight edge from the steering head along the top of the backbone and look for daylight; if there's none you win! If it's bent, report back and we'll get you sorted out in no time.

Pete

[Roby466]

Excellent! Thanks for the tip. I’ll take a look tomorrow as more sand blasting occurs. Cheers
David

[coolpool]

If there was a front fender on it the most obvious sign are burn holes or signs of rub marks on the back of it.

[Roby466]

Is this what you mean? Yes there were rub marks on the front fender frlm rubbing on the front of the engine. 251201251201

[Roby466]

I just saw the youtube video to straighten it.

[coolpool]

Yes that one is tweaked a bit. I'm not sure you'll be able to see my post in the main forum area but I've included the link just the same. Basically I stand the frame on its arse, place a 4 x 4 piece of timber where the air box should be then put a 3 ton bottle jack up against the steering head under the frame; jack away until it's straight! I went slightly over to compensate for spring back.
http://www.3wheelerworld.com/showthread.php/159796-Another-70-Comes-Home?highlight=atc+70

[Roby466]

Thanks for that, I just went and saw your thread. Will do that this weekend. I thought I would have to buy a bottle jack but I think my old Land Rover Discovery has one in the engine compartment :)

[Roby466]

Alright! I spent most of Sunday sandblasting the chassis parts and the wheel halves. I think next will be por-15 on the chassis, then black top coat. Front fork will get primer and red automotive paint (once I figure out how to use a real paint gun).
Chassis will also get straightened next week once I’m back from a small business trip.
The plastics were painted so I will try the permatex paint stripper spray. I saw on youtube (it must be true) that it diesn’t harm plastics. I will need a front fender too. I’m still looking for a tank :)

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[coolpool]

I've seen quite a few different opinions on how to coat over POR with some saying you can't and others saying you can; do you have a sure fire method?

[Roby466]

I built a top for a M101cdn trailer to make an expedition trailer and the top is all welded sheet metal. I put two coats of por15 on there and then sanded it a bit once dry and applied top coat. The por15 instructions say we have to top coat otherwise it will turn grey due to UV.

[coolpool]

I built a top for a M101cdn trailer to make an expedition trailer and the top is all welded sheet metal. I put two coats of por15 on there and then sanded it a bit once dry and applied top coat. The por15 instructions say we have to top coat otherwise it will turn grey due to UV.

Yes it'll get UV pooched pretty quick, sounds like it'll work! M101CDN2 to be exact, lol! I happen to have a 1953 M100 Cdn, a 1951 M100 US Army and a 1947 T3-C Bantam. Trying to sell the Bantam at the moment but no dice! I thought one of the off road expedition types would want it?

[Roby466]

You’re right... 101cdn2.
You would think some expedition type would want it. Especially in Alberta, the expedition scene is quite good there.
Plan for mine is roof top tent and storage inside for now and later I might build in kitchen stuff.

[wonderboy]

Another way to top-coat POR15 other than waiting for it to cure and then scuffing it down is to catch it when it is still tacky during the drying process. I cleaned up and coated the axle on my snowmobile trailer this way. The instructions gave better details, but basically after the 2nd coat has cured a bit, but is still tacky, you lightly dust it with primer (I used Rustoleum spray primer). The key was a very light coat.

I just looked on their site, and I can't find anything about this method of topcoating, but I know I read it in the instructions somewhere.

At any rate, once I hit it with the light primer coat I let it cure. Then I applied the final coat of paint on top. The primer bonded with teh still somewhat uncured POR15 to provide a bond for the final topcoat.

The axle is holding up really nicely after 3 winters of use.

[Roby466]

Nice! I’ll give that a try I think. I’ll try a 2 part primer as I have an old paint gun I want to try for this project :)

[Roby466]

Well I will have a 3 weeks pause in the build... my 2004 Discovery needs head gaskets so that's what now occupies the hour and a half of free time I have at night after the kids go to bed... there is lots to remove to get to the heads. And while I'm in there I'll check the lifters and change the oil pump gear, timing chain and gears and water pump. The joys of old LR ownership :) The time they run between failures make up for the failure rate though, they are great machines!
The build will resume once this thing starts up again :)
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[knappyfeet]

Forget the Discovery ..........tell us more about the sandcast!

[Roby466]

alright, I have been off the forum for a while, sorry about that!
Well I did most of the work, all is left is the tank. However it wasn't running that great so I checked the timing... well... apparently the keyway is all damaged so that would explain why it runs poorly, the timing must be very retarded. There was a makeshift key in there and it appears a pawl from the start recoil fell off and went behind the flywheel and that is probably what damaged the keyway... I will post pictures from my phone in a minute you will see what I mean.
What do you think I can do?
Thanks
David

[Roby466]

https://uploads.tapatalk-cdn.com/20190521/7e64701c392a69252962597be7b08142.jpg

[Roby466]

Then the painting started. I did the trick for coating Por-15 with the Por-15 two part urethane paint for the black. The red and silver parts were done with epoxy primer, colour paint and 2k clear

https://uploads.tapatalk-cdn.com/20190521/c2346d8e5fcafcbdabbd307dca89f1f8.jpg

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[Roby466]

https://uploads.tapatalk-cdn.com/20190521/97767ae744380d8d8ed7d5e037e9eabb.jpg

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[Roby466]

https://uploads.tapatalk-cdn.com/20190521/0e339aff49b5e05621b98d00922f79ac.jpg

I did a bit of home zinc plating and yellow chromating

https://uploads.tapatalk-cdn.com/20190521/432606d2195d6e911fa9ac218ec8c833.jpg

And more assembly

https://uploads.tapatalk-cdn.com/20190521/faf29423451508aa2704ebb01bb445df.jpg

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[Roby466]

Some more old paint stripping and a road test...

https://uploads.tapatalk-cdn.com/20190521/357e2ba12663652f06b05148dc957d59.jpg

https://uploads.tapatalk-cdn.com/20190521/69563a845990698141d208d3102fab74.jpg

The temporary tank is from a Chinese made pocket bike :).

The old tank is being redone. I welded the holes at the bottom and I will lead it at the bottom. That will hide my welds and seal it should small cracks start around the weak metal that I welded. I will also use tinning and lead to fix the dent before the same 2k epoxy primer and paint system.

https://uploads.tapatalk-cdn.com/20190521/ae97af296f019c7e6402744f5905f8a4.jpg

https://uploads.tapatalk-cdn.com/20190521/a4854f7640530308e7cc3d820d46f535.jpg

[Roby466]

Now for the damaged keyway... what do you think I can do?

https://uploads.tapatalk-cdn.com/20190521/71cb44aab09b5301f9f3f184c85f6d3f.jpg

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[ironchop]

Oh man! That keyway is destroyed. You should remove that crank to have it welded up, in my opinion

Nice build so far.

Did you find a kit to do the yellow chromate and if so, which did you use?

[knappyfeet]

Very nice!

The yellow chromates.......I'm assuming you are using the Caswell system. It's a very good system.....I have one myself. What are you using for a power source for the plating ?

Split the case and source a replacement crank.....it's the way to go. Then you can clean up the barrel, case and covers.

[Roby466]

That’s it. I’m using the casweld kit. Well just the chromates from them. For the plating I use vinegar and epsom salts and zinc roof strips. For power supply when plating small bolts I was using a small charger 6V supply but for large parts I used my 12v car charger on 2a setting. It bubbled good :). I switched it a couple times on the 10a setting but that appeared a bit too powerful... i use a fish-tank waterfall for agitating the water.

[Roby466]

I just purchased a used crankshaft on ebay but I was really hoping to rebuild the engine next winter and use the bike this summer a little bit. I can weld so I wonder if it could work to add some steel in the mangled keyway and clean it up with a dremel. Or would that make it distord due to the heat?

[Roby466]

Well the used crankshaft I received was not the right one (gotta love ebay). It was not even the one in the auction’s picture. I suppose it may be from a bigger engine. https://uploads.tapatalk-cdn.com/20190605/c76ffb339c842eb7693b896f6b79efd7.jpg

[Roby466]

So I repaired the old one. Wrapped a wet rag to keep the heat down and went at it. The small air file is not great but helps for this kind of job when you can’t move a regular file much. Not too bad I think. Now I have to find a die to clean up the thread and try it.
https://uploads.tapatalk-cdn.com/20190605/3b60bba7831deb14078f6becd832b7dc.jpg

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[shortline10]

Wouldn’t hurt to use some valve lapping past to reset the flywheel on the crankshaft. Just put a generous amount on both the shaft and flywheel keyway areas , rotate back and forth until the surfaces look mated .
A good snug / mated fit is very important or it will sheer again .

[DAM shop]

Wouldn’t hurt to use some valve lapping past to reset the flywheel on the crankshaft. Just put a generous amount on both the shaft and flywheel keyway areas , rotate back and forth until the surfaces look mated .
A good snug / mated fit is very important or it will sheer again .

That's a nice little trick Shortline, never considered that

[Roby466]

Good trick! I will use some gearing blue to see the high spots and file them down first, then I’ll definitely do the valve lapping compound trick. Thanks!

[Roby466]

So I also received my replacement crankshaft. Supposedly for a atc70 but as you see in the picture it’s much bigger. Of course ebay seller says it’s the right one and I’m wrong and wants me to ship it back and cover shipping both ways (which is twice the price of the sale). It looks like a 110cc crank...


https://uploads.tapatalk-cdn.com/20190610/f99de4032d009ade1eae6fe83e5d9a61.jpg

[Roby466]

Morning! It’s been a while. I had the bike running by welding the end of the crankshaft and making a new key.

That wasn’t too great as the timing wasn’t quite right. Also the bike was smoking quite a bit so I found a used crankshaft and flywheel (other flywheel was wobbly on the shaft) and I started the teardown.
https://uploads.tapatalk-cdn.com/20200110/2cded7971c053b1c7ba1a572c8c0e91a.jpghttps://uploads.tapatalk-cdn.com/20200110/1fef3b67f4797721e7b082f40d682f3d.jpghttps://uploads.tapatalk-cdn.com/20200110/91279f66ff4919c6e6a5515438832a05.jpghttps://uploads.tapatalk-cdn.com/20200110/fcd8d5c19474e7cc1014d92d55b11fbf.jpghttps://uploads.tapatalk-cdn.com/20200110/912e07dff64baf37fb4aff904fce464c.jpghttps://uploads.tapatalk-cdn.com/20200110/8f73e9b0c12b2c1182751afe790dec55.jpg

[Roby466]

So I have a few questions (of course):
-cylinder seems fine. We can still see the marks from the cross honing. Do I need to do anything with it you think?
-rings look good. Is it better to replace them or leave them alone?
-see that piston? Slight rubbing on the skirt but it looks ok. I suppose it was oversized 0.75 at some point from the stamping?
-my camshaft has some wear. There are some original used ones on ebay and a NOS but the NOS is for 78 to 80... per the part number but the seller lists for up to 1986 (and the aftermarket equivalent is the same from 78 to 86... but the original has a part number difference) big differences you have seen? Anybody else has swapped them?

Thanks!!
David

[coolpool]

Another option for the top end is to buy a complete Chinese kit from eBay. I got a complete cylinder, piston/rings, wrist pin and gaskets to my door (Canada) for less than $100.00 a few years ago for my 1973 70. I know some would shudder about OEM but it fit great and runs perfect to this day.