4.6 RV8 Not Suitable For a Manual Gearbox

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garrycol
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4.6 RV8 Not Suitable For a Manual Gearbox

Post by garrycol »

I was speaking to a guy tonight about putting a RV8 4.6 in my Landrover FC101 as a replacement for the 3.5. He has a 5.1 RV8 in his 101.

He said that the 4.6 was never designed to go in front of a manual gearbox and as such the thrust bearing in the centre of 4.6 crankshaft had thinner thrust faces as the shocks in running an auto were less that that of a manual with heavy clutch changes. As a result the amount that the crank can move forward and back is excessive for manual use and before long the crank movement will be out of tolerances.

I have not heard this issue before so am just curious if anyone else has heard this and if it is correct what is the solution - eg what thrust bearing will correct this?

Cheers

Garry



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Post by Coops »

My 4.6 is on a 2wd manual box in my car 👍
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Blown v8
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Post by Blown v8 »

Mine has aT5 behind it

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ChrisJC
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Post by ChrisJC »

As far as I know, the only difference between the cranks on a 4.0 and 4.6 is the throw. And the 4.0 engine was most definitely fitted to manual vehicles.

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Post by DEVONMAN »

ChrisJC wrote:As far as I know, the only difference between the cranks on a 4.0 and 4.6 is the throw. And the 4.0 engine was most definitely fitted to manual vehicles.

Chris.
Good point. The 4.6/4.0 and some late 3.9's have a thrust bearing attached to just the upper main bearing shell. Earlier engines had a thrust bearing attached to both the upper and lower bearing. This gave twice as much thrust area and longer wear resistance. However unless you are a clutch pedal rider I can't see that the later spec will have a problem. Better oils /materials must help also.
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stevieturbo
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Post by stevieturbo »

Never had an issue with the 4.6 in mine either and with a heavier than std clutch.
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garrycol
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Post by garrycol »

Thanks for the responses - so I take it that no one has heard of this.

Unfortunately evidence that people have a 4.6 in front of a manual is no real evidence as the end play issue does not become evident until higher kms have accumulated. There are no issues with a new or low km engine.

Cheers - I will chalk it down to rumour.

Garry

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Post by stevieturbo »

Well look at it another way.

Have these people show proof of engines that suffered a problem through using a manual transmission.

I suspect they wont be able to. Not all engines have full 360 thrusts.

MGRV8 used a manual trans with a 4.0 as did some TVR's, Some TVR's also use the 4.6 and are all manual.

And I'm sure there are some Land Rovers out there, Discoverys if not RR's that used a manual trans with either of the engines.


Really...there are far more things to worry about than that
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Post by DEVONMAN »

I vaguely remember reading that the change was made in later engines as it was not considered ideal to put lateral forces on the bolt on lower part of the centre main bearing.
1950 A40 Devon Hotrod with 5.0 twin turbo RV8.
EDIS8 wasted spark, Holley Injection.
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garrycol
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Post by garrycol »

Thanks - just putting it out there to see if anybody had heard anything along these lines - it is not a 360 vs 180 degree bearing issue but the thickness of the thrust faces - they are supposedly only half the thickness of say a 3.5 thrust bearing to suit the 4.6 crankshaft.

Cheers

Garry

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Post by Coops »

8yrs I've been abusing my 4. 6 on a manual box 👍😉😂
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MS2 V3.57 Ecu mapable efi and wasted spark ignition.
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russell_ram
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Post by russell_ram »

Plenty of factory built 4.0 Discovery's. Crank to thrust bearing interface is identical to 4.6.

Not an issue.
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