Crank bearing clearance Increase.

TVRleigh · Post by **TVRleigh** » Tue Mar 25, 2008 12:06 am

How do you increase the clearance by 0.0005" - 0.001"

as its very slightly too tight. 0.001" - 0.0008" Idealy I want it to be 0.002"

bearing 5 Rear seems the tightest 0.0008".

clearances messure with plasti gauge with everything dry.

the crank spins freely when at 30 LB/FT but turns but not freely at 50 (70 rear. with oiled bearings.

All parts are stanard. (Large Journal crank)

Thanks
Leigh

Post by **katanaman** » Tue Mar 25, 2008 9:36 am

you will have to get the crank polished to do this I think. If everything is standard then either you have a bad set of bearings or your main journals need trued up. Have you measured up the crank to see if that is correct? Either way something is wrong and you would be better finding the problem rather than fudging it.

TVRleigh · Post by **TVRleigh** » Tue Mar 25, 2008 11:43 am

I did mesure the crank and I think it was within limmits but was on the large side of the limits.

As said the gap is only 0.1 tho too much.

one thing in did notice was where the shells go into the block, the recess on the block was a little ruff to the touch not sure if you could mesure it. but was thinking of just using some wet and dry just to make them smooth.

I was thinking of wrapping plasti gauge all round the journal to see if there are any high spots.

Also is 50 and 70 LB/FT correct for the large journals.

CastleMGBV8 · Post by **CastleMGBV8** » Tue Mar 25, 2008 12:21 pm

Leigh,

Have you got the main bearing caps mated to the correct position in the block, if not this will give you clearance and alignment issues.

I would not advise rubbing anything down with wet and dry! Make sure everything is scrupulously clean, even a spec of dust can make a difference.

Double check the shells to make sure you havn't been given oversize ones by mistake, it's not unknown for the wrong bearings to be in the wrong package, it's happened to me!

Kevin.

TVRleigh · Post by **TVRleigh** » Tue Mar 25, 2008 12:38 pm

Will double check,

Every thing was very clean.

but will re-clean, as its only the smallest of amounts, as it fine at 30LB/FT

Plus it still turning at 50/70 just not freely.

Was not going to take any metal off as suck just take off the rufness.

I would have thought if I had a 10 thou oversize shell it would be a hell of a lot worse. as its only less than 1/2 a thou out

Post by **katanaman** » Tue Mar 25, 2008 2:06 pm

yes it wont be wrong shells but they could be badly sized I suppose. don't get the rough behind the shells. It shouldn't be like that and sounds like spun bearing but then that shouldn't be able to happen without major devastation. If it was me I would get the mains measured to see what was going on or have the caps lightly skimmed and the mains re-circled/honed. I assume you have done all this testing with the cross bolts in and torqued properly? If not then that could well be your problem. The main caps wont be the proper shape until the cross bolts are in.

TVRleigh · Post by **TVRleigh** » Tue Mar 25, 2008 2:12 pm

katanaman wrote:yes it wont be wrong shells but they could be badly sized I suppose. don't get the rough behind the shells. It shouldn't be like that and sounds like spun bearing but then that shouldn't be able to happen without major devastation. If it was me I would get the mains measured to see what was going on or have the caps lightly skimmed and the mains re-circled/honed. I assume you have done all this testing with the cross bolts in and torqued properly? If not then that could well be your problem. The main caps wont be the proper shape until the cross bolts are in.

oops.
Did not put the cross bolts in, did not think they would affect the clearance.

Will try again tonight.

Problem is all info on how to check stuff is all pre-x-bolt.

I think the faces have got a little rough due to being in the parts washer etc. does not look like shell has slipped, it's not that bad.

Thanks for asking the basic question, a lot of times its the simple things.

TVRleigh · Post by **TVRleigh** » Fri Apr 04, 2008 12:11 pm

katanaman wrote:yes it wont be wrong shells but they could be badly sized I suppose. don't get the rough behind the shells. It shouldn't be like that and sounds like spun bearing but then that shouldn't be able to happen without major devastation. If it was me I would get the mains measured to see what was going on or have the caps lightly skimmed and the mains re-circled/honed. I assume you have done all this testing with the cross bolts in and torqued properly? If not then that could well be your problem. The main caps wont be the proper shape until the cross bolts are in.

TOP MAN.

Put the X-bolts in and it sweet now.
It's got to come out again to be balanced.

Is there a correct sequance i.e. do you torqe the caps 1st or the x-bolts.
Also what the correct torque also is the end cap still 20Lb more than the rest.

Post by **katanaman** » Fri Apr 04, 2008 4:26 pm

yes the main bolts are done first stage 1 10lbs 2nd stage 53lbs rear main cap is 10lbs then 68lbs then you do the cross bolts 10lbs then 33lbs. This is from the RR manual.

TVRleigh · Post by **TVRleigh** » Fri Apr 04, 2008 4:33 pm

Thank you

only have the SD1 manual.

That says 50 and 70 in 3 stages.

I did the X-bolts to 30.

I don't think the 2/3 Lb is going to make much difference.