Poorly fitting steel main caps
Turbo Mini Forums

Hi
Had some steel caps supplied & fitted to my block then line bored at the machine shop
Got it back today and the overhang on the washers on both the outer main caps is so large that it makes contact with the crank (and stops it rotating)
Now I struggle to believe that the machiner missed this and if so how accurate do you think the machining is?

They are bolts instead of studs and only the 4 centre main cap bolts & washers where apparently supplied with the kit
Just now really nervous about the quality of the work as its to thousandths of an inch
Also had the block rebored, faced and crank ground +10


The washer is also pushed as far away from the crank as possible in the pictures too
All dowels lining up etc.

Attachments:

942kb

979.11kb

Edited by Will on 27th May, 2015.

I would take machine the wacher to fit. Or no wachers at all.

you can do anything if you set your mind to it...
i rather blow it up winning than keep it together losing.

finish date set for project 1... march 2018

Also these washers are meant to be "special EN24T" washers

Going by the photos alone. those washers don't seem the right sort at all for the bolts used.

Can you photo the underside of the bolt head and the cap top face where the bolt would land (without a washer).

And the markings on the bolt head.

Schrödinger's cat - so which one am I ???

Thanks
Also there is quite a lot of side to side play of the bolt until bolted down
Is that normal?

Attachments:

1.26mb

1.44mb

1.23mb

Edited by Will on 27th May, 2015.

Firstly I wouldn't use a washer.

Secondly, are they the correct tensile strength bolts?

There's a few threads on the subject

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=236552

http://www.turbominis.co.uk/forums/index.p...id=154716&fr=25

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Edited by Will on 27th May, 2015.

Yes those bolt are not good enough

Where did you get the caps?

I dont think theres too much to worry about tho, ditch the washers and buy an ARP stud kit. If your going to the trouble of having steel caps then might as well go all the way and fit the studs too. If you really must have bolts then just buy 12.9 cap head bolts (allen heads)

I dont really see it impacting on the machining. You cant blame the machinist for the caps being supplied with dodgy bolts and chocolate washers. You would have thought they would have said something i guess but then again you wouldn't expect to buy a set of caps and have them come with those fixings.

hmm.

It is always hard when this happens. you hope the people did a good job but in the end you need to check everything and measure everything before you build the engine. Half the time you need tools that are expensive and where the handling is not trivial if you want to measure properly.

I know that does not help, but been there done that..and burned a few times

The mains are very highly stressed. You are talking 780 G in compression in the rod at a mundane 5000 rpm (in this case the direction that pulls on the bolts) and almost 2000 G at 7800. Ergo it better be bloody tight!

The basic premise of any bolted joint is that it pulls the rod/bolt to a certain tension. if that washer crushes (i.e. it is soft) the tension is gone and the joint is loose (and parts start to do the cuckoos clock thing).

I would rather have a shouldered bolt (like a build in washer). Or have the proper grade hardened washers.

(As Slater said: get a set of ARP studs. expensive but still a lot less than a main that is on the loose)

IMHO it is Weird/pretty improbable that it does not uses dowels/bushes for the cap positioning. normally the caps are a very tight fit on the dowels/bushes/registers (whack them on with the palm of your hand or a copper hammer). The bolt should pull only, the dowels should hold the position sideways very firmly (plus friction due the the pull down) .

So even though the size might be spot on after machining you still have to make sure that you get the cap back in exactly the same position after bolting the whole lot together. a cap than can move at all when positioned is imho definitly wrong.

The scuff marks on the cap suggests that it is pretty soft (first pic) as well.

where did those parts come from ?

Edited by Sir Yun on 28th May, 2015.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

I guess they torqued the caps down to specified torque before line boring? Did they ask you for the torque setting?

https://www.facebook.com/pages/Fusion-Fabri..._homepage_panel

www.fusionfabs.co.uk



1/4mile in 13.2sec @ 111 terminal on 15psi

Didn't give them any torque settings
And although the machine shop didn't tell me where the caps came from I know who they are from
Basically the machine shop I put my block in for the work lost my centre main caps (how I don't know)
A good few months pass with me badgering on and on until they finally admitted it and agreed to replace them and line bore it
I've picked it up paid full wack for all the work
And because of the washer overlap, losing parts etc. I really don't trust the quality of workmanship
Also pretty sure when you bore out a block you give them one of the Pistons to test fit too?
As the Piston rings are all still in their sealed bag and I supplied them
Just feel like I've been done over
Wanted a solid block I didn't have to worry about tbh!!



Working to tolerances of thousands of an inch I struggle to believe that you'd miss such an overhang
And if that's been missed I'm almost certain a lot of other things have been too :(

Edited by Will on 27th May, 2015.

When my block went in for machining the guy asked me to bring the pistons and rods crank and.block he took a look at everything before he started work. He also checked the centre main after.I had that machined aswell so it's down to experience of the place no harm in taking it to someone else to get a another opion

I share your concerns (losing parts , not owning up it just sounds dodgy) and would get a third party to look at it. The machining might still be done perfectly, but a dodgy cap will take out an engine so better be safe than poor.

(maybe I misunderstood and the cap is tight but the bolt loose to the hole, that is no problem. )

Edited by Sir Yun on 28th May, 2015.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

Dry build it and plastigauge it. Either it will be right or it won't. If it isn't then fire it back at the machine shop and tell them to sort it.

From the photos,

1 The underside of the bolt head is intended for either a small diameter hardened washer or direct on the cap face.

2 It can't be the cap face as it has a chamfer around the bolt hole.....

3 Bolt grade is definately wrong.

4 If there are no sleeve dowels (or real dowels in the caps) and the bolts are loose in the cap holes, the line boring (if it was ever really done) is worthless.

Sorry that sounds harsh but everything you've photo'd says to me thay haven't a clue what they were doing.

Schrödinger's cat - so which one am I ???

I've been assured that the caps where torqued up properly before line boring
And apparently the crank didn't need dry fitting after hence why the washer overlap was missed
And as the bolts are the wrong ones I've been given arp studs & nuts

So I guess just see if they fit
The caps have dowels but the bolts have a lot of side to side play when not torqued down
The worrying thing is the place that made the caps insist they supply the grade 8 bolts not the grade 5 I have
I am abit worried I can't check the rest without access to mega expensive equipment

Schrödinger's cat - so which one am I ???

Plastigauge.

Ok great,
Just found out the supplier does know they use low-grade bolts and that they should be grade 8
And thats fine as they've never had a problem

So quick warning about MED!!

And Thanks Tom ive just googled that stuff and looks pretty epic
Anyway of checking whether a bore has been done well?

Edited by Will on 28th May, 2015.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

i would check the locating dowels are in the caps also ,

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

Didn't give them any torque settings
And although the machine shop didn't tell me where the caps came from I know who they are from
Basically the machine shop I put my block in for the work lost my centre main caps (how I don't know)
A good few months pass with me badgering on and on until they finally admitted it and agreed to replace them and line bore it
I've picked it up paid full wack for all the work
And because of the washer overlap, losing parts etc. I really don't trust the quality of workmanship
Also pretty sure when you bore out a block you give them one of the Pistons to test fit too?
As the Piston rings are all still in their sealed bag and I supplied them
Just feel like I've been done over
Wanted a solid block I didn't have to worry about tbh!!



Working to tolerances of thousands of an inch I struggle to believe that you'd miss such an overhang
And if that's been missed I'm almost certain a lot of other things have been too :(

some of your concerns now make a little sense to me,

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

Just seen this on eBay:

http://www.ebay.co.uk/itm/111679109414

KAD Mini centre strap (only KAD due to the backing paper that the caps photographed on!)

Bought from MED in the sellers description.

yep thats MED one
Next question is , is the clearance of the stud from the top of the nut ok?

As ive got conflicting info from MED
One is an email saying
To fit the AFS stud kit the hole in the block need to be drilled deeper, so that when the cap with the nut is fitted onto the stud there is no stud protruding out of the top of the nut

But a picture on their website shows different
http://www.med-engineering.co.uk/catalogue...es/_MG_7309.JPG
Cant confirm as they close at 4

what a faff, hope its worth the effort!

Attachments:

1.62mb

Edited by Will on 29th May, 2015.

okay, had a bit of dealing with studs,


you will need to relive the gearbox to clear the front and rear mains studs, but TBH, that stud looks very long, doubt you'll find the clearance.

personally I would cut the studs down, as drilling & taping the block deeper will be a faf. I belive the ARP set is actually designed for inline engines....

I have used the minispares uprated cooper S stud set, much better length wise, but a bit till needs to come out of the box... also to go in the non S block you need to turn the shoulder off them to clear the dowels.

talking of Dowels... Swiftune do some nice billet ones that are thicker, for under 20 quid,

when machining/cutting the studs, keep them cool so not to temper them!