8 Bolt TR6 flywheel/crank.

8 Bolt TR6 flywheel/crank.

Author
Discussion

vearlytr6

Original Poster:

40 posts

37 months

Thursday 12th December 2019
quotequote all
Hello, I am upgrading? my TR6 motor and would like to know ways of fixing the attaching of flywheel / crankshaft. Two of four threads in flywheel are damaged (first 1/2") Regards,Michael.

garagewidow

1,261 posts

138 months

Friday 13th December 2019
quotequote all
Hi,

Check how far the threads go into the crank,can't remember but i'm sure there will be an inch or more of thread,then get the damaged area machined out and fit longer bolts.
I've used longer 12.9 tensile allen bolts without issues,if you get some at 3" or so they will have a shoulder(need to check the industry standard for shoulder lengths) which helps to dowel the flywheel as well as the standard dowel.
just make sure they don't bottom out in the hole,measure the depth and cut the bolts at least 1/4"shorter and fit them with quality thread lock.you don't want those buggers coming loose.

You could get 8 holes done but they might compromise the strength of the crank spigot as it isn't that large.

Edited by garagewidow on Friday 13th December 19:30

vearlytr6

Original Poster:

40 posts

37 months

Saturday 14th December 2019
quotequote all
Hello Garagewidow, The depth of the hole is 1" and the flywheel is 0.4".I can buy ARP flywheel bolts 230-7306 @1.25" but as the first 0.5" in two holes is damaged (has been cleaned with thread tap and can screw a bolt all the way in but...) Regards,Michael.

tapkaJohnD

1,615 posts

172 months

Saturday 14th December 2019
quotequote all
Very similar thread over on the Sideways Technology site: http://sideways-technologies.co.uk/forums/index.ph...

John

vearlytr6

Original Poster:

40 posts

37 months

Sunday 15th December 2019
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Hello Tapkajohnd, It is,I am it. Regards,Michael.

vearlytr6

Original Poster:

40 posts

37 months

Sunday 15th December 2019
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Sorry ,Will post a couple of pictures (if I can) and keep you updated.Michael.

vearlytr6

Original Poster:

40 posts

37 months

Monday 16th December 2019
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Hello all, here are a couple of photo's of the problem.Regards,Michael.









vearlytr6

Original Poster:

40 posts

37 months

Monday 16th December 2019
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LTP

919 posts

80 months

Thursday 19th December 2019
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Find a local machine shop that has Helicoils then get new bolts. I wouldn't advocate cleaning up the damage and reducing the number of threads engaged. Helicoil is a standard automotive way of saving a threaded hole and using the original sized bolts.

You can get a kit and do it yourself if you're handy.
https://www.youtube.com/watch?v=9rtiFBC0wms

vearlytr6

Original Poster:

40 posts

37 months

Friday 20th December 2019
quotequote all
Hello LTP, My son has heli-coil sets but we don't think they would be good enough for a 2.5 L flywheel. The plan is to have 7 holes/threads tapped and 5/8" head, longer ARP bolts (to be made by them) fitted. (plus the dowel). Regards,Michael.

vearlytr6

Original Poster:

40 posts

37 months

Thursday 26th December 2019
quotequote all
Hello, Will post some photos when I get the crank/flywheel and bolts back (they are the other side of the bush fires which have the highways closed at present). 3.5 million hectares and climbing in NSW. Regards,Michael.

LTP

919 posts

80 months

Wednesday 1st January 2020
quotequote all
vearlytr6 said:
we don't think they would be good enough for a 2.5 L flywheel.
Done correctly Helicoiled holes are as strong as the originals; as you can then use the original bolts the joint is as good as new, if not better

Excessive bolting torque, corrosion and even wear – these and other reasons can lead to thread damage. HELICOIL® Plus thread inserts were developed in a variety of designs, ensuring quick thread repair. The use of non-wearing HELICOIL® Plus thread inserts not only repairs threads but also increases thread load.
Source - https://www.boellhoff.com/gb-en/products-and-servi...

In most cases the newly threaded bolthole is actually stronger when a Heli-Coil™ Insert is installed!
Source - http://www.newmetalworker.com/Reviews/helicoilsrvu...

vearlytr6

Original Poster:

40 posts

37 months

Thursday 16th January 2020
quotequote all
Hello LTP, The three extra holes have been drilled in flywheel and crank has been drilled and tapped,and going to use ARP bolts p/n 230-7306 1.25" (set of 6 @ $42.27)as ARP wanted $119.04 EACH to finish off 8 x 1.37" bolts. Will put up some pictures when I get the crank etc. back. Regards,Michael.

vearlytr6

Original Poster:

40 posts

37 months

Friday 15th January
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Here a photo of crank and flywheel. Michael.

vearlytr6

Original Poster:

40 posts

37 months

Friday 15th January
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Hello, Tried to upload two photos, but it wouldn't work. Michael.

silentbrown

6,743 posts

84 months

Tuesday 16th February
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Would you need to rebalance the crankshaft after that?