42 replies to this topic

[SirBallD]

Hi all,
I bought an engine on ebay (mistake #1).
It's an 998cc a+ series.
I asked the seller about the state of the engine and technical specifications...and I believed what he told me (mistake #2).
I was told it was an standard 998cc a+, but it's not. It was a 998cc a+ but it wasn't STD but +.03.
Upon disassembly I found some annoying issues with the different components.
My main issue right now is the crankshaft. It's a 12a1451 which, to my knowledge is a pre a+ 998cc crank.
Someone did some welding on the flywheel end of the crank, and it's not pretty.
 20210425_094754.jpg   61.67K   7 downloads
 20210425_094711.jpg   34.08K   4 downloads

My initial thoughts was to use it as a paper weight. Is there any way that this crank is salvageable? I've read about lapping etc, but I'm not sure if this is the way to go. I really don't want to spend all my money on trail'n'error projects (potential mistake #3, 4 & 5), but on the other hand the amount of spareparts available in Denmark is on the low side. I know that I can still order from UK...but what if I buy my mistake #6 if I order a used crank?
Any thoughts from you guys.
Regards Stefan

[MiniMadRacer]

To me that does look scrap, and of course here in the UK a 998 Crank isnt too hard to source, I agree though not so easy for yourself in Denmark.. Lets see what others think

 

The part Number 12a1451, was used for both A and A+ 998 cranks, and I dont believe there is much if any difference in a supposedly later A or A+ crank

 

[MiniMadRacer]

One other thought.. be careful removing the primary gear, pulling it over that "weld" could destrpy the bushes, assuming they werent destroyed fitting it in the first place

[johnR]

The weld doesn't look structural? If not I suppose it could be re-finished without a problem.

[sonikk4]

Personally i would weigh that in and put it down to experience. We have all been there at one point in time.

[Spider]

It looks to me like the Flywheel has been fretting (rubbing) on the taper. Somewhat common issue usually from not fitting the Flywheel tight enough in the first place.

 

They often look worse than they really are. When you put this in perspective across a variety of engines, the same taper is used for 120 ft/lb big racers as is on the 850. If you are only intending street use , I'd have it dressed, lap the Flywheel to it and used it. It has more (much more) that 50% surface area left, though I see on one side it's fretted on the ends of the taper.

[SirBallD]

One other thought.. be careful removing the primary gear, pulling it over that "weld" could destrpy the bushes, assuming they werent destroyed fitting it in the first place

I tried very carefully to pull the primary gear off, but it wasn't possible. So I left it on for now.

[dodge44]

That damage looks more like fretting than welding to me so the next question is what is the condition of the taper on the flywheel as that will need either work or replacing as well?

 

Roger

[SirBallD]

It looks to me like the Flywheel has been fretting (rubbing) on the taper. Somewhat common issue usually from not fitting the Flywheel tight enough in the first place.
 
They often look worse than they really are. When you put this in perspective across a variety of engines, the same taper is used for 120 ft/lb big racers as is on the 850. If you are only intending street use , I'd have it dressed, lap the Flywheel to it and used it. It has more (much more) that 50% surface area left, though I see on one side it's fretted on the ends of the taper.

I'll bring it to the machineshop and ask if they can do some magic.
It's only intended for street use. I really hope that I can have it fixed.

[MiniMadRacer]

If it can be dressed two things to be careful of..

 

1. The Flywheel fits properly and doesnt ride too far up the dressed taper pinching the primary gear... you could end up with all sorts of clutch problems then... as Spider has intimated, do not be tempted to NOT fully tighten the Flywheel bolt on re fitting

 

2. The Flywheels fits perfectly perpendicular to the crank, or you will have awful vibrations

[SirBallD]

I didn't give the flywheel any thoughts. Here is some pictures of the flywheel and it doesn't look too good.
 20210425_111122.jpg   59.29K   1 downloads
 20210425_111210.jpg   68.96K   1 downloads
Does this mean a replacement of the flywheel is in its place or is it possible to fix this?

[SirBallD]

That damage looks more like fretting than welding to me so the next question is what is the condition of the taper on the flywheel as that will need either work or replacing as well?
 
Roger

I agree, but it's really difficult to take pictures that shows that it bulges upwards like a weld and not down into the material.
I've tried giving it a shot.
 20210425_110930.jpg   24.49K   1 downloads

[MiniMadRacer]

The engineering shop will prob need to see the crank and flywheel.. others will know better than me... but its possible that if the crank is dressed and the flywheel too, it might be too lose a fit..... best see what the "shop" says... the other thing of course is the cost of  "dressing" versus the cost of a "replacement"

[SirBallD]

If it can be dressed two things to be careful of..
 
1. The Flywheel fits properly and doesnt ride too far up the dressed taper pinching the primary gear... you could end up with all sorts of clutch problems then... as Spider has intimated, do not be tempted to NOT fully tighten the Flywheel bolt on re fitting
 
2. The Flywheels fits perfectly perpendicular to the crank, or you will have awful vibrations

Both point 1 and 2 would be awful if not performed correctly. My plan is to fix the mini and drive around on Sundays and in sunshine. No racing, just relaxing...and it's difficult to relax if it feels like sitting in a helicopter, shaking all around the place
I'm positive that the guys at the machineshop can do a great job.

[Maccmike8]

Im guessing the OP wouldnt know, if these very important aspects were successful, until reassembly and running.

 

Any faults would mean another big job so if it were me, Id either get a reputable machine shop to do it (££££) or buy a good replacement crank.