93 replies to this topic

[MRA]

I didn't mean all the way along I meant both sides of the block (this should be STRAP not block) if you machine one side it bends due to internal stresses.... it will bow

Also I wouldn't cut the thread on those bolts as they are a rolled thread and you will drastically reduce there strength, it really is best to clearance drill the hole plus a lot cheaper and quicker... especially if your machinist has a radial drilling machine...

Regards Martin

Edited by mra-minis.co.uk, 23 June 2009 - 06:12 PM.

[mike.]

Right well yeah thats fine then because i got 5mm taken off both faces

Right so basically i just need to get the first lot of thread drilled out to give clearance for the shouldered part of the bolt. Just need to get it to match the other side then it'll all be good.

I must be able to use a couple of those washers because thats what turbodave suggested in the firstplace to avoid the bolt bottoming out.

[Sprocket]

DO NOT CUT ANY THREAD ON THE BOLT!!!!! It will surely fail with catastriohic results.

High tensile bolts have a rolled thread. This is done before the bolt is heat treated. Cutting a thread creates stress risers where fatigue cracks can propigate which leads to sudden failure.

DO NOT USE EXTRA WASHERS TO PACK OUT THE EXTRA LENGTH!!!!!!

The best and esiest option to resolve this can of worms, would be to drill out the first threads in the block and cut thread down on the good side to match the side that had the original problem. Anything less and its not really ideal


What really p**s's me off is that all this stems from some tuning company selling sub standard parts without any regard for the consequences to other peoples property!!!

[mike.]

Yeah i see what you mean.

Right. So what i need is to get the block on a pillar drill and get some of the threads removed from the good side of the block, so that the amount of thread is equal in both sides.

When you say cut the thread down? You mean after drilling, get the machinest to run a tap down there to clean up the beginning of the thread to accept the bolts properly after removing the first few threads


Yeah i'm pretty annoyed at it all myself. Its caused me alot of hassle really. Although to be honest, now i've looked at it all and thought about it abit more, i should have realized that the bolts were too short. I didn't realise the dowels in the block went in a good few mm and that those bolts would only be engaged in a few threads.

[stardude]

have you spoken to the company that supplied you with the strap??

[mike.]

Yeah i emailed them this topic and asked them what they thought.

They replied saying it looked okay to helicoil that area...

[stardude]

Yeah i emailed them this topic and asked them what they thought.

They replied saying it looked okay to helicoil that area...

wow they sound very concerned! they should be the ones footing the bill for the extra work thats having to be done do to the substandard parts that they supplied!

[bigmotherwhale]

im not suprised that morspeed sold you dodgy stuff they did some work for me and i wasnt best pleased, infact i had to redo it all myself.

why not bite the bullet and buy a miglia spec 4 bolt center main, send the rubbish one back to morspeed and demand a refund, at least you will know you have done a propper job and there will be no chance of failure.

Edited by bigmotherwhale, 23 June 2009 - 11:37 PM.

[mike.]

Nah, I've spent past my budget on this engine so far anyway and i've still got megajolt to buy!

I just want to get it built now and get driving again!

[mike.]

Right.

I think this is finally sorted

Took the block to this machining guy, got about 5mm of thread removed from the block, blew the swarf out and screwed the bolt it. It had made no difference!

So he drew on the bottom and shoulder of the bolt and screwed it in. When he took it out the mark on the shoulder was untouched but the mark on the bottom of the bolt was.

So basically what was stopping the bolt going all the way down was the bolt bottoming out in the block! So he measured the depth of the thread at 38mm. This means that not all the thread holes are the same during manufacturing! He said this was very unusual as normally all threads in this application would be drilled and tapped the same.

So the damaged thread hole was 42mm deep, where as the other one 38mm deep! So that 6mm of extra depth the bolt need was being stopped by the bolt bottoming out in the block and not the shoulder as I thought originally. Unfountunatly, i only found this out after we had removed so thread from the block!

Anyway, what we did in the end was simply mill the required amount off the end of the bolt. As you can see:



Meaning both bolts now go in enough to clamp the cap when using one washer under each, and i know i'm getting the maximum amount of thread engagment possible in this case.

So it means i'll now have about 20mm thread engagement, so way better than the original bolts supplied with the strap and around the same as the original bolts from the engine.


So as long as it doesn't strip the threads again when i go to put the crank in (i'll hang myself if it does) then i'm all sorted!

So thanks to all the people that've showed interest/helped me with this issue

[mike.]

Another quickie. As highlighted in my original post, when i installed new standard size thrust washers, the crank had no end float at all. But with the old washers in, i got about 4 thou of endfloat.

Why would that be?

As long as i've got the correct amount of endfloat, theres no harm using the old thrust washers is there?

[stardude]

glad you have got it all sorted!

[MRA]

Right.

So basically what was stopping the bolt going all the way down was the bolt bottoming out in the block! So he measured the depth of the thread at 38mm. This means that not all the thread holes are the same during manufacturing! He said this was very unusual as normally all threads in this application would be drilled and tapped the same.

So the damaged thread hole was 42mm deep, where as the other one 38mm deep! So that 6mm of extra depth the bolt need was being stopped by the bolt bottoming out in the block and not the shoulder as I thought originally. Unfountunatly, i only found this out after we had removed so thread from the block!

This would be because someone on the drilling line decided to change or sharpen a drill and put it back in without setting it correctly...... as long as it fell between the min and max tolerance that was all that mattered

Of course today's engine manufacturing is nothing like this A story I heard a few years ago..... was that a cost down exercise to save money had highlighted an area where money could be saved............. they stopped putting these high line (manufacturer will remain annonymouse) engine blocks, cranks, etc through the parts washer mayhem ensued....

Regards Martin

Edited by mra-minis.co.uk, 24 June 2009 - 04:12 PM.

[mike.]

Right.

So basically what was stopping the bolt going all the way down was the bolt bottoming out in the block! So he measured the depth of the thread at 38mm. This means that not all the thread holes are the same during manufacturing! He said this was very unusual as normally all threads in this application would be drilled and tapped the same.

So the damaged thread hole was 42mm deep, where as the other one 38mm deep! So that 6mm of extra depth the bolt need was being stopped by the bolt bottoming out in the block and not the shoulder as I thought originally. Unfountunatly, i only found this out after we had removed so thread from the block!

This would be because someone on the drilling line decided to change or sharpen a drill and put it back in without setting it correctly...... as long as it fell between the min and max tolerance that was all that mattered

Of course today's engine manufacturing is nothing like this A story I heard a few years ago..... was that a cost down exercise to save money had highlighted an area where money could be saved............. they stopped putting these high line (manufacturer will remain annonymouse) engine blocks, cranks, etc through the parts washer mayhem ensued....

Regards Martin

Yeah he said it was really unusual, i just assumed they'd both be the same because i couldn't see any reason for them not to be!

[mike.]

Success at last

All went together no problems, crank turned beautifully with light pressure. Pistons slipped in easily and all torque up with no problems.

So thats all in there now, all turns as smooth as you like and just generally really pleased with the build so far