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Alex

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Ok I've got low oil pressure on my 2000 general opinion of people cleverer than I is that its the bearings on the crank worn.
Long term I want to rebuild a tr6 engine for it but funds just wont allow that at this time.
So how easy is it to change the crank bearings?
If the crank was a bit worn obviously the ideal would be pull the engine out and have it reground?
If I chose to just put new bearing on a worn crank could/would this increase my oil pressure for a reasonable length of time?

If I for arguments sake lets say the oil pressure is 20/25 at 3000rpm would it make it round britain?


I'm hoping this figure may improve with an oil change and spin on conversion but obviusly no guarantees.


Thanks for the help in the rb prep thread  :)

Alex

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It would make it, but to be honest, its not that difficult to do the crank bearings, I've done them before and you usually get back to about 50psi hot 3000rpm.

So,

Get the car up high, on axle stands on the chassis rails.

You need to lower the front crossmember by about 4 inches, so undo the 2 tie bars where they go into the chassis rails, undo the steering connection to the rack, undo 8 bolts holding the crossmember to the car and lower the whole assembly by about 4-5 inches. (mind the brake pipes!!)

Then, after draining the sump, undo all the sump bolts and withdraw the sump. you need to fiddle to get it past the oil pump and the crossmember, but it will come out.

Now you are looking at the bottom end of the engine.

Undo 1 big end cap and remove the shells. they will be stamped on the back "std" or +0.10 or +0.20 etc to find the right size.

Slacken all the main bearing caps slightly, (you need to remove the front bridge piece) then take off one cap altogether. One side of the shell is in the cap, the other is ontop of the crank. Carefully rotoate the crank whilst giving the shell a push with your finger and it should roll out with the turn of the crank. Again, check the sizes.

Carefully inspect the crank. You are looking for deep scores and bits missing. 99% of the time you can get away with just shelling it. I've NEVER had to have a crank machined, just changed the shells.

So, off the your friendly Triumph parts person.

1 set of big end shells (you know the size now!)
1 set of main bearings (you also know the size now!)

1 set of standard thurst washers (behind the rear main bearing)

1 sump gasket
1 oil pump (if you feel like it, you might as we whilst you are there)

Whole lot should cost £100, plus some oil and filters.

Refit as above.

Job done.

I usually allow about 3 hours to strip, an hour to put all the shells in and 3 hours to put back together.

Good luck, call if you need help!!

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Here's a tip for removing the upper shells from the mains if they won't budge by turning the crank.

Insert the head of a small split pin into the oil hole in the crank journal and fold the ends out flat against the journal.  A bit of grease will hold it in place.  Then rotate the crank until the protruding parts of the split pin bear against the shell and push it out. Obviously the thickness of the split pin legs must be less than that of the bearing shell...

Good luck

Steve H

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Is it really that straight forward?
As I'm sure many are aware this all started due to lack of oil when I initially fitted this recon engine.
I dont mind admitting I'm more than a little worried that I'll do something wrong and be worse off than I am currently.Although of course theres only one way to get experiance.

Alex

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I think one small item of importance has been missed in terms of removal and replacement, the bearing shells will only rotate 1 way and 1 way only and each shell has an "ear" that locates into the block and into the bearing cap, be sure to take them out in the right direction otherwise you might try to force them a way in which they don't want to go.

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Okay then guys - any tips about the good and bad suppliers of bearings?

I hear people talking about good ones and cheap ones - but I haven't a clue which is which. Any brands I should look for, or suppliers I should contact (GT6 engine BTW).

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Vandervell is king of bearings, the very best. Some are still available, but pricey, try chris witor, and canleys may have some too, phone and ask.
Failing that, county sell some under the "king" name I believe, and are tri-metal. AVOID the county normal bearings at all costs.
Allso NOS glacier/ae ones are OK, not as good as vandervell etc but much better than normal county stuff.
Obviously need to get the old ones out first for inspection and to get sizes. Dont forget thrusts, get one 5 and one 10 thou bigger than whats fitted as well as a pair the same, see what you can squeeze in.

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cliftyhanger wrote:
Failing that, county sell some under the "king" name I believe, and are tri-metal. AVOID the county normal bearings at all costs.


It's not quite that straightforward. As far as I am aware, all County bearings are made in Israel by King. However, not all King bearings are tri-metal, be certain to specify the tri-metal versions as buying by brand alone is not enough.
Cheers,
Bill.

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Alex - when checking for wear on the crank journals the tip I was given was to feel for any scores with your fingernails. If they're bad enough to feel then they need sorting.

I just managed to get my hands on Vandervell bearings in OZ, in fact I have a spare set of mains, but they're standard size only.

I think Canley Classics have been advertising them of late.

I reckon you should give it a go yourself - good luck

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If we were building a new engine with a re-ground crank and spending lots of money then yes, VP shells or Glacier.

However, all we are trying to do is to get some decent oil pressure and get a few more miles out of an already tired engine.

County shells will be fine, but a good points about the tabs on the shells.

I have done several engines this way with cheap bearings and all have been fine for tens of thousands of miles.

Alex, where in the UK are you, I might be able to give you a hand if you are nervous about this?

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AlanChatterton wrote:
I have done several engines this way with cheap bearings and all have been fine for tens of thousands of miles.


Ditto that. Back in the late 80s early 90s I kept the Spit running for 40,000 miles by changing the  big end and main bearings this way. In fact when the bodywork died and I had to take the car off the road the engine was still going fine... ::)

Try to keep everything spotlessly clean when you're fitting the new bearings and refitting the bearing caps etc.

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Alex wrote:

Does your oil light come on at tickover when its hot?



No, thankfully!  Hot oil pressure at tickover can't be too far off warning lamp level - I estimate 15-20 psi from the gauge :-(   Lamps usually illuminate around 10psi.

Have you tried fitting a gauge?  

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Still I reckon best to avoid the nasty county ones. Worth a few quid extra for peace of mind.
The haines manual makes the point that changing BE every 30,000 and nains at 40,000 (which is daft, do both at the same time) the cranks should last a very long time. My first 2500 engine was untouched and 100,00 when I got it. New bearings, a quick DIY hone and new rings, it was excellent for 30,000+ miles, let down by a little bore wear on no5 I think. Oil pressure was still very good, 60psi hot running at 3000.
I am a bit fan of re-bearing engines, but not with duff bearings.
Clive

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