10 replies to this topic

[ozz1]

Just realised in machining the centre cap flat for a centre main, the thrusts can float about and hit the sharp edges left on the main cap. The obvious solution seems to be to use a wider strap and machine locating grooves but I cant find one. 
 
My idea is to make a bridging plate and then drill and tap the strap so it locates. I would countersink the plate and use M6 cap heads and then weld them to the (mild steel) bridging plate so they are captive.
 
 
- I have attached some drawings to explain what I'm banging on about!
 
 
I would tig tabs on the strap either side of the tangs but suitably preheating en24t is a very precise process...
Im reluctant to put locating dowels in the main cap as others have as the thrust faces will wear faster than the steel dowles, galling the crank face in time to come.
 
 
Any issues you can see with this design please let me know, or for that matter any blindingly obvious solutions I have probably overlooked.
Also whilst the cap is off is it worth putting some arp chromoly washers under the main bolts?
 
 
Thanks, Oscar
 
 
 
 

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Edited by ozz1, 11 November 2016 - 10:49 AM.

[gazza82]

Sounds like you took too much off the centre cap .. I'm sure mine has the locating slots left in it with the strap in-place ..

 

 ARP_Washers_Fitted.jpg   84.34K   38 downloads

Edited by gazza82, 10 November 2016 - 05:48 PM.

[ozz1]

Sounds like you took too much off the centre cap .. I'm sure mine has the locating slots left in it with the strap in-place ..

 

ARP_Washers_Fitted.jpg

In terms of material removed it's fine, just the rotary cutter was too wide. 1275 cap is different to 998 too. Just need to find a solution that ideally doesnt involve taking out the crank. will def invest in arp washers! Cheers

[panky]

How about a piece of thin flat bar under the strap, the same width as the cap

Edited by panky, 10 November 2016 - 06:20 PM.

[ozz1]

Bump

[jaydee]

Without removing the crank, solution is swapping that strap for a wider one, on this new strap you are going you cut a slot for the thrust tang

Otherwise crank out then cut the slot on the block on the opposite side side from the  centre cap slot

[ozz1]

Without removing the crank, solution is swapping that strap for a wider one, on this new strap you are going you cut a slot for the thrust tang

Otherwise crank out then cut the slot on the block on the opposite side side from the  centre cap slot

Can't find a wider strap anywhere on the web, is there anyone that makes them up? Thanks

[panky]

Doesn't sound right to me but I may be missing something. Wouldn't my idea of a piece of sheet steel under the cap bent over with notches for the bearing tangs work? Basically a big tab washer - or would that be considered a bodge.

[Shifty]

I've heard of people drilling and tapping the centre bearing so the thrust can be bolted into place

[Spider]

I'm not remotely in favour of the idea and concept of a Centre Main Strap on any of these engines.

 

However, as you have gone past the point of no return here, why not find some steel bar that's wider than what you have now, close to or wider than the Centre Main Bearing Cap, have it milled to the same width and then cut locating slots in to that.

[ozz1]

Doesn't sound right to me but I may be missing something. Wouldn't my idea of a piece of sheet steel under the cap bent over with notches for the bearing tangs work? Basically a big tab washer - or would that be considered a bodge.

It would need to be an incompressible high tensile steel, ideally en24t of a reasonable thickness. It would need milling and surface grinding on both sides and adding another point of separation between the cap and the strap would only create weakness - nice solution in theory though!