Thread: Fearing the worse

Engine number on milled surface on block passenger side about half way along block. If it has not been milled off with a block decking in the past...


Pete

Be a bit careful with this if it doesn't have the same engine number stamped on.

4.6 is more than 15% bigger than a 3.5 so by the letter of the law needs an engineers certificate in NSW.
Regards Philip A

Originally Posted by PhilipA

Be a bit careful with this if it doesn't have the same engine number stamped on.

4.6 is more than 15% bigger than a 3.5 so by the letter of the law needs an engineers certificate in NSW.
Regards Philip A

I shall investigate when I get down & dirty with her again, in the mean time, I have another technical question, probably an easy one! My other RRC has a 5 speed manual box, the transfer box has 4 positions Hi Lo Hi diff lock & Lo Diff lock. The central diff lock is very useful, makes a big difference when needed. This "new" RRC has an auto box but only a 2 position transfer lever, Hi & Lo. Does this mean there is no diff lock? BTW it is or was an 89 Vougue.

Jez

Jez -

The original 3.5 engine number may have been put on the block so no checks etc had to be done for rego/engineering etc.

As mentioned the 4.0/4.6 engines are cross bolted and the 3.5/3.9 engines are not.

Along the bottom of either side of the block just above the sump join you will see the bolts on a 4.0/4.6

A 4.6 (4.0 block) and the bolts are obvious


The crank of a 4.6


A 3.9 engine - note the cross bolt pads where the cross bolts would go if the 3.9 had them


And a poor pic of a 3.5 as it is still in the car - note no pads, holes or bolts.


So as a pointer of what engine you have - just climb under and have a look.

No pads = 3.5
Pads but no holes/bolts = 3.9
Bolts = 4.0 or 4.6.

Garry

Originally Posted by snowbound

This "new" RRC has an auto box but only a 2 position transfer lever, Hi & Lo. Does this mean there is no diff lock? BTW it is or was an 89 Vougue.

Jez

I suspect it has the BW viscous coupling tfr case. When the viscous coupling detects slips it locks - same as a diff lock (well not really but for simplicity ....)

Basically if the viscous coupling has input and output shafts turning at different speeds it causes the fluid inside to thicken and basically locks up sending locked drive to the front wheels. Like a CDL but works automatically. If the back wheels spin faster than the fronts are turning the VCU detects this and locks provides locked drive to the front wheels so matching drive to the rear.

For the tech heads - yes that is an over simplified explanation.

Garry

Garry, Thank you so much. It's too dark now, but I shall have a look tomorrow and post my findings! Also, thank you for the simple but understandable answer to my auto question.

Jez

Originally Posted by garrycol

I suspect it has the BW viscous coupling tfr case. When the viscous coupling detects slips it locks - same as a diff lock (well not really but for simplicity ....)

Basically if the viscous coupling has input and output shafts turning at different speeds it causes the fluid inside to thicken and basically locks up sending locked drive to the front wheels. Like a CDL but works automatically. If the back wheels spin faster than the fronts are turning the VCU detects this and locks provides locked drive to the front wheels so matching drive to the rear.

For the tech heads - yes that is an over simplified explanation.

Garry

Interestingly the '89 RRC I bought for wrecking had obviously been driven for some time without a front drive shaft. Its performance in high range was quite adequate without any noticeable slippage in the viscous coupling, even when stationary. I assumed it was seized until I put it in low range and the front flange started to spin with force applied. It appeared to act more like a clutch that slips when sufficient load is applied. On a corner that force would normally come from the differing wheel tracks and provide enough slip to prevent windup. It essentially started off 99% locked.

I also saw a guy once who dynoed his P38 with the front shaft removed. Perfectly safe at anything other than stall speed in first. It slipped quite a bit ascending my steep driveway.

Originally Posted by bee utey

Interestingly the '89 RRC I bought for wrecking had obviously been driven for some time without a front drive shaft. Its performance in high range was quite adequate without any noticeable slippage in the viscous coupling, even when stationary. I assumed it was seized until I put it in low range and the front flange started to spin with force applied. It appeared to act more like a clutch that slips when sufficient load is applied. On a corner that force would normally come from the differing wheel tracks and provide enough slip to prevent windup. It essentially started off 99% locked.

I also saw a guy once who dynoed his P38 with the front shaft removed. Perfectly safe at anything other than stall speed in first. It slipped quite a bit ascending my steep driveway.

Interesting I did not know they were tight enough to drive with one shaft removed I always thought they would slip like a bastard unless they were seized.