L28 block brace/girdle

[peter mc]

RN26 is a very hard wearing steel, when you are tightening bolts down you don't want the steel to give or wear.

That is why mild steel is not up for the job.

By the way that is enough fat jokes!!!! lol

[luvemfast]

But it defeats the purpose if your bolting through a mild steel plate?

Maybe I'll use 4140 (like M200) then.

[NZeder]

There was an engine built here in NZ that use an RB crank girdle - it was modified for the L6 block and line bored to match. I think this path was taken as it was a one off, as we know the RB bore spacing is the same as the L6, this girdle includes the main caps too. But that was a bit of engineering to get it to work as the rear main is very different between the 2 and I am not sure how it was done but heard it had been done.

[ozconnection]

The photo above looks more like a windage tray, than a block girdle!

 

Go to Google and have a look at what a windage tray looks like.

[nat0_240_chevZ]

yep i aggre with nzedder, yes why re-invent the wheel,

the rb is the next gen l-series and most things like size, spacing, bolt positions are exactly the same in most cases....

easier to do with an existing cast item also.

otherwise if you do go down the road of making them, just get the blank laser cut from some decent plate ie 350 grade MSteel, then machine the req'd grooves for gasket sealing etc. drill tap, c/bore/csk as req'd all in the one machining operation.

If i actually still ownerd an L-series id grab an rb item first.

otherwise if you really dont want to use struct grade alloy steels (mild / carbon) then yes you could use a cr-mo 4140/4340 or even a d2 tool steel, DO not even think about using ally however, as thermal expansion difference will cause sealing issues....eventually.

We can laser cut 40mm plate @ a real stretch ie cut defination lacks after about 30mm.

nat0

[MaygZ]

I've never had anything to do with a girdle before ( I know Lurch still wears one - He's actually 5'8" and fat until he puts it on  ), but the pictured one would do the job pretty well if one were to tap into the bottoms of all the main caps and secure, I reckon.  After all, if I am correct, it's job is to reduce lateral movement of the mains and therefore reduce load and vibration by doing so.

 

I do agree that counter sinking the bolts would make the end result more asthetic, but I don't think it would improve performance in any way.

 

I also think that any gasket, other than a thin film of silastic, would reduce the benefit of the plate, as it would reduce the rigidity of the plate.

 

Just my 2.2 cents.

 

MaygZ

[luvemfast]

If you want to see what Z's are doing laps under 2minutes at the Island, have a look under them in the pits, they're the ones with the oil puddle underneath them. Due to the flex of the block.

I agree that a gasket between the block and brace would be detrimental to rigidity.

The countersunk screws are more to give clearance for the sump to be put back on, not to look pretty.

Tapping into the mains would be a BIG no no in my book. That would create weak spots in them. Using spacers and bolting through the brace, spacer and mains would be the best way to go.

 

I'm waiting for the CNC to be free for me to mill a timber template to check size and mods made. Then its time for some quotes from laser cutting. Hopefully this week.

[Riceburner]

No puddles under mine...... It's all along the cross members and floorpan  Could you cut a grove top and bottom of it and use an 'O' ring type of seal?

[ozconnection]

That's a great idea in regards to gasket sealing and maintaining bolt tension.

 

Too bad there isn't an L sump that runs with this idea. Now I'd buy that in a second! It may negate the need for a brace or at least move the necessity to a higher power level.

 

Hmmmm.

 

 

[peter mc]

The rear main leak is from crank flex. The shaft is moving up and down this is the reason the seal is damaged.

When replacing bearings on big hp l6 engines the mains are normally out of round on 1 & 6 by 3-4thou this would indicate that the crank is flexing through its length.

A girdle will go a long way in reducing crank flex and hopefully help bearing life, as for using an RB girdle this would be a monumental and expensive way around the problem as you would need to line bore the main tunnel which in impractical and the man that built this girdle was no fool and also built some of OZ's best L series long before most of us had Z's or knew how to build motors!

[NZeder]

as for using an RB girdle this would be a monumental and expensive way around the problem as you would need to line bore the main tunnel which in impractical

Yep I did not say it was a good or bad idea - just that someone had under taken the task here in NZ. It would be a mammoth task for sure and having a well designed girdle that can be CNC would be a much cheaper option in the long run as more could be produced from the design work once done. As you have stated there is already a design floating around Oz so if this works why re-invent the wheel (I should listen to that myself - custom one of rear brake setup...silly man...all for a internal drum for the park brake - dual purpose cars always a compromise ) 

[nat0_240_chevZ]

lol, yes compromise or to not spare a cent or minute..........

why cnc a template in wood on a mill???

i could cnc punch a sheet/plate template to within +/- 0.1mm which would only, seriously take about 2-3 minutes if appropriate tools are already loaded into machine (ie piggyback off another job.)

just doing out of wood, sounds like checking it with a rubber ruler....lol

 

nat0

[luvemfast]

just doing out of wood, sounds like checking it with a rubber ruler....lol

Just checking hole positions, nothing more.

Doing it out of 1mm steel now anyway.

[luvemfast]

I machined a prototype out of 1.5mm Galvabond this arvo.

Have to adjust a few holes a mm or so. But apart from that, I'll be getting quotes from the laser cutters ASAP

Here are some progress pics.

Simon

[dazzed]

Simon dont waste your time doing all that it allready been done and are currently available , they dont just bolt in too theres a fair bit of machining to do as well .contact me if you need to know more, cheers .

[peter mc]

The beauty of this girdle is that you dont have to do any machining.

There is no need because this bolts to the top of the main tunnels with spaces.

[luvemfast]

Simon dont waste your time doing all that

Geez Daniel, I've already done the hard work mate.

The time is spent, I can't get it back.

These were available previously, but have made some minor improvements.

[dazzed]

Geez Daniel, I've already done the hard work mate.

The time is spent, I can't get it back.

These were available previously, but have made some minor improvements.

oh sorry Simon , not wasted time , i fitted one to and engine a while ago and quite a few were made at the same time, there is some block machining to do which is a must , the idea of the brace/ Girdle isnt so much about block flexing is about main caps moving it just so happens the girdle bolts to the sump bolts bit of a double wammy, there is a lot of very carefull work required to fit this and a procedure put in place, cleaniness, and everything in top condition as you dont want to pull it apart once u have done it in a hurry. cheers Dan

[Riceburner]

I have no idea with this sort of mod but..........How thick is this girlde? Will there be enough clearance between the lower sump and the crossmember? Also seeing as it fits between the block and sump will the oil pick up need a spacer to ensure it stays deep enough in the sump?

[peter mc]

there is no mods to the block in this girdle . it is 6mm thick and the oil pickup bolts through to the block

[MaygZ]

will the oil pick up need a spacer to ensure it stays deep enough in the sump?

 

Put a little more oil in the car.  Somebody asked earlier about modifying the dip stick, but this too confused me as another 0.5 litre of oil would do it all some good.  And before someone pipes up with comments about the crank hitting the extra oil, remember that the sump is a mm or 2 lower.

 

Maygz (having yet another cranky day due to decreases in Karma)

[peter mc]

the  pick up is in the same spot in the sump. the dip stick will read 6mm lower but it will have the same amount of oil ...

[Riceburner]

As I am getting one of these, what/how many bolts are required and where can I get them from? There will be more silly questions from me I just can't think of any yet 

[luvemfast]

As I am getting one of these, what/how many bolts are required and where can I get them from? There will be more silly questions from me I just can't think of any yet 

Which bolts do you speak?

Sump bolts will need to be longer (≈6mm), you will need some M8 countersunk cap screws (unbrako) and some longer mains studs (ARP).

Although, Gerhard has just used long Unbrako SHCS with hardened washers for his mains, and that motor has been together for years.

You'll also need 10.5mm thick washers, Ø6.8mm drill and M8 tap.

[DatZed]

+1 for me. PM me with price and bank details.