Harrison diff setup

[muzzza]

Thanks for your responses and words of welcome Guys........Nice knowing there are others out there with the same " illness "

In the short time I have been building, I have met a lot of really helpful Guys.....has been great.

Dropping the rear of the cradle is an option........but as the cradle supports the inboard ends of all the suspension arms, it also effects camber curves, squat characteristics under hard acceleration, the rear roll centre and the roll axis of the entire car.

Target will be to get pinion and gearbox axes as close as possible to parallel with no more than about 15mm offset tbetween axes to ensure needle rollers in uni joints get enough movement to lubricate properly.

May look at raising front of cradle a little and rolling diff head up within the cradle. (rubber cradle mounts will need attention by all accounts - especially without snubbers that have been removed )

The current set-up (16" AVO coilovers - 300lb springs )
has the halfshafts sitting almost straight at full "Droop " ( no load )

Would be interested to know how much preload you Guys are running on your coilovers and roughly how much droop.
( in other words - a rough idea of how far the car compresses the rear suspension to arrive at normal ride height ) and does the car sit OK at this height ? ( 17 inch rims )

PS trying to get as much info as possible at this stage.......so with this build it all works first time !! ( should have / would have / if I was doing it again etc )

Thanks..........Murray

[WKB]

Originally Posted by muzzza

May look at raising front of cradle a little and rolling diff head up within the cradle. (rubber cradle mounts will need attention by all accounts - especially without snubbers that have been removed )

Murray,
Your mention of raising the front of the diff made a few more brain cells work and I remembered how I did get the required diff angle.
On the cradle bushes, I cut the steel tubing through the bush level with both sides of the cradle arms. The large washers I made did two things, 1, they clamped the cradle to chassis which reduced the effect of the rubber bushes to almost nothing and 2, I could use this large washer as a shim.
On the diff I replaced the rubber bushes in the front of it with a round piece of steel that was flush with both sides of the flange. Again I used large fabricated washers underneath of the flange to bolt the diff. The top of the flange bolted flush to the cradle. With the new position the diff I just fine tuned with with different thickness fabricated washers under the rear cradle bolts.

The diff rubbers were replaced on a recomendation of the company that did tailshaft. They said they have seen these rubbers ripped out on acceleration with high horsepower cars. As you are using a chev motor that might not be an issue.
The secondary side effect was I could change the diff angle.

[muzzza]

Thanks Warren,

Seems anything that minimises movement of the cradle is not all bad.

Subframe on rubber bushes is a great idea for crusin'..........but a bit short of ideal for a car leaning towards a race car.

I appreciate your note re " Chev motor "........I only used it as it was left over from a previous project...........perhaps I should save up for a "Ford "

Appreciate your input Warren.

Regards Murray

[Rebel1]

Originally Posted by muzzza

Target will be to get pinion and gearbox axes as close as possible to parallel with no more than about 15mm offset tbetween axes to ensure needle rollers in uni joints get enough movement to lubricate properly.

Thanks..........Murray

Is the engine in the Harrison moved a little to the right or is it on the chassis center line?.

[muzzza]

Had a quick measure...........and egine is about 10mm closer to left ( passenger side ) of car.

Murray

[Rebel1]

Originally Posted by muzzza

Had a quick measure...........and egine is about 10mm closer to left ( passenger side ) of car.
Murray

That's interesting Murray, must be for header clearance ?.

Given our short tailshafts I would have expected it to be moved to the right to minimize the diff pinion offset.

I'm guessing a pinion center offset of maybe 40mm so a 10mm left engine position increases that to 50mm between gearbox output and diff pinion .