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Sprint engine brace/ladder frame
http://forum.triumphdolomite.co.uk/viewtopic.php?f=3&t=32344
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Author:  lrderry [ Tue Mar 14, 2017 3:08 am ]
Post subject:  Sprint engine brace/ladder frame

Hi All
Building a Sprint race engine over in the US. Looking to see if anyone has a drawing or CAD model for an engine block brace/ ladder frame? All set up to machine one if anyone can help.
Thanks
Mark
Chicago
USA

Author:  gmsclassics [ Wed Mar 15, 2017 6:26 am ]
Post subject:  Re: Sprint engine brace/ladder frame

Can't help with the drawing I'm afraid. I bought mine from Rob at

http://www.sprintspeed.co.uk/pages/prod ... ct-engine/

Also use his lightened flywheel, centre release bearing and twin plate clutch. All good quality products.

Geoff

Author:  lrderry [ Tue Mar 28, 2017 2:20 am ]
Post subject:  Re: Sprint engine brace/ladder frame

Does anyone have an extra one they want to sell?
Thanks
Mark

Author:  GTS290N [ Sun May 28, 2017 8:29 am ]
Post subject:  Re: Sprint engine brace/ladder frame

This any use?
http://www.ebay.co.uk/itm/Triumph-Dolom ... Sw8lpZKZE1

Author:  soe8m [ Sun May 28, 2017 2:45 pm ]
Post subject:  Re: Sprint engine brace/ladder frame

That is the optical version. Not a functional one.

Jeroen.

Author:  Triumph1300 [ Sun May 28, 2017 3:04 pm ]
Post subject:  Re: Sprint engine brace/ladder frame

Can you explain what you mean Jeroen?

Author:  Galileo [ Sun May 28, 2017 6:59 pm ]
Post subject:  Re: Sprint engine brace/ladder frame

I'm guessing he means it looks pretty but that's about all it does...

Did I read somewhere that the main bearing girdle should be at least 10mm to be effective on the Sprint engine? I could easily be mistaken, I'm known as a mine of useless information.

Edit: Yes I did, on this forum! viewtopic.php?p=86606#p86606

Author:  soe8m [ Sun May 28, 2017 9:52 pm ]
Post subject:  Re: Sprint engine brace/ladder frame

This type of brace does not really support.

Blocks do crack around the threaded part/web where the main bearingcap bolts go in. This faillure is because most blocks have cylinders bored too deep and most are bored into the threaded area of the web. These too deep drilled blocks will never be reliable competition engines.

The best is to start with engineblocks that are accidentally drilled not too deep by the factory and best former 1850 engineblocks because there’s more flesh left around the web area.

When you are lucky to have or to find one you must round the sharp edge of the cilinderbore at the bottom into the web. Now there’s no “edge” to start a crack and your engine probably doesn’t need a brace at the first place.
The next improvement will be an arp stud set and torqueing a fine threaded nut on the main bearing cap instead of turn/pulling a bolt in the weakest threaded part of the engine when tightening.

The brace in the advert are in a few variations. This one you fit the long studs into the engine, put the mainbearing caps over the crankchaft, then fit a certain amount of washers till you are about the same height of the sump face and then tighten all. It is in the certain amount of washers.

When torqueing such a long stud with a certain amount of washers the actual torque can never be accurate. You simply do not know how tight the main bearing cap actually is.
The next thing is are all the amounts of washer the same height at every bearing cap? Slightly over or slightly under? Not to determine with a certain amount of washers. One slighlty bent washer will measure ok but cause a wrong height when tightened.
When this brace is fitted and you should put a straight ruler over the “ladder” you will see they differ in heigt after tightening because of the different amount of washers needed. This shows that it does not add any strenght, only weight.

Should this brace be made of very super strong turbo non deforming steel then the certain amount of washers can cause when torqueing, an uneven strain inside the engine. It will in theory pull the web towards the brace and have an even more uncontolled torque of the main bearing caps but looking at this lump of steel it does certainly deform instead of pulling the web.

A variation if this i did see with double nuts. This has the same effect. Stud, mainbearingcap, nut to tighten cap, nut, brace and nut. The extra nut under the brace does replace the certain amount of washers but the total effect will be the same. They are available with solid bushes inbetween but these have also the same effect.
But if such a flexplate does make you feel better you may fit one ofcourse.

There is an alternative but you have to fabricate yourself. I was lucky to have one at the same go of this batch of three in total. These are new main bearing caps so the engine has to be line bored again. The caps are fitted with arp stud/nut combi and are fitted the original way. No extra strain on the web than the normal. The brace is somewhat thicker and has slots where the caps slot in tight. All is tightened and then all faces machined to the same height. The brace does not pull or push on the web, only supports the caps.

Jeroen

Attachments:
brace2.jpg
brace2.jpg [ 47.06 KiB | Viewed 1310 times ]
brace1.jpg
brace1.jpg [ 47.75 KiB | Viewed 1310 times ]

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