Road Runner Nest

Just spent some time tinkering today. Confirmed the 8 3/4 rear is a Sure Grip. Now tell me how can I tell what gears are in the rear end.

My brother was over and we turned the axle 1 1/3 revs to 1 wheel rev. Not sure if on a Sure Grip we can figure out the rear end gears or not.

Finally put a timeing light on it. It reads 40 deg at idle and 50 with the revs up. Unknown cam (it's lumpy) or compression. 383ci, Weiland Highrise, Edelbrock 4B # 14062251. ? flow anyone know where I can find this carbs flow rate?

Any thoughts on this info?

Finally got the rear brakes kinda working. It seems a few pieces are missing.

A generic manual showed an Anti rattle strut and spring, self adjusting lever/spring, Parking break lever, and over load spring. My rear drums had none of this in them. What do you know about any of these pieces on a 71 RR. We adjusted the brakes so they grab a little now. They hadn't at all before. It was scary stopping with just front drums. At least I have a little in the rear now.

Any input welcome and appreciated!

Thanks
CtownRunner
Chris

Sorry I should have put this in Q & A section. Dave can you move it?

My brother was over and we turned the axle 1 1/3 revs to 1 wheel rev. Not sure if on a Sure Grip we can figure out the rear end gears or not.

You sure about that? One tire rotation should be 3-4 axle rotations...that's how you get your axle "ratio". 3.23 turns of the axle to 1 turn of the wheel equals a 3.23:1 axle ratio, or 3.23 gears. The smaller pinion gear will always turn many more times than the larger ring gear. Hope this helps....

Yeah, it doesn't make sense. Thats why I posted. I just rechecked it solo.
On the jacks, both wheels off the ground, in neutral, I turned the drive shaft by hand. The wheel turned 1x for every 1 1/2 drive shaft rotations.

It is driveing me crazy! Can this be right. It seems to drive well. Shity fuel use but they all are. Would a full drag car be set up like this?

I don't think it's a Sure Grip either. As I turn the drive shaft sometime both wheels turn, sometimes one then maybe the other or both. Kinda hard to do this Solo. I had to stop and start the turning of the drive shaft a few times. It was a start and stop effort to turn it.

In Park as I turn one wheel by hand the other side turns in the other direction. I turn the wheel in a forward direction the other side spins backward.



Ctown

CtownRunner wrote:Yeah, it doesn't make sense. Thats why I posted. I just rechecked it solo.
On the jacks, both wheels off the ground, in neutral, I turned the drive shaft by hand. The wheel turned 1x for every 1 1/2 drive shaft rotations.

It is driveing me crazy! Can this be right. It seems to drive well. Shity fuel use but they all are. Would a full drag car be set up like this?

I don't think it's a Sure Grip either. As I turn the drive shaft sometime both wheels turn, sometimes one then maybe the other or both. Kinda hard to do this Solo. I had to stop and start the turning of the drive shaft a few times. It was a start and stop effort to turn it.

In Park as I turn one wheel by hand the other side turns in the other direction. I turn the wheel in a forward direction the other side spins backward.



Ctown

That's pretty strange...I've never seen anything geared so high. 2.50s are about the highest I've seen. Hmmmm...

Turning one wheel by hand and having the other go in the opposite direction says you have a peg-legger. Doesn't matter about what gear you have selected, but in Park, it shouldn't move at all. There might be a little play in Park, but you should not be able to turn either of your wheels for any measurable rotation. "Park" is a selection made in the tranny and it has nothing to do with the rear end...your driveshaft should not move when the tranny is in Park.

Someone, please correct me if I'm wrong...

Its time to quit fooling around. Put the rear end on jacks pull off the diff. cover and take a peak. Very odd info.

lb71fish wrote:Its time to quit fooling around. Put the rear end on jacks pull off the diff. cover and take a peak. Very odd info.

Its an 8 3/4 rear it does not have a cover as they are a carrier type rearend.Open rearends are a little tricky to tell the ratio so i went down to the garage to try it.
Yes with both rear tires off the ground the axles turn even though the tranny is in park but on the ground they lock up.Also with one tire on the ground and in nuetral turning the driveshaft produced 1/2 rev of the gear set for 1 rev of the tire(ex. 3.23 ratio produced a 1.6 driveshaft revolutions)

Is any of this making sense?

Answer to the original guestion:
My guess is that they are 2.76 gears

brian

Well at least now I know it is NOT a Sure Grip, most likely 2.76 gears. Now I really think the timeing is very advanced but it runs well. Maybe this weekend I can back it off a little and see how it goes.

Who is going to the Nats in Aug? Celebrating the RR this year.

Thanks for your input on this. Wish I had learned more 30 yrs ago.


Ctown

As for the timeing issue:did you plug the vacuum line when checking at idle? Actually it sounds like the vacuum line might be hooked to the wrong port on the carb letting it advance as soon as it fires.
A good starting point is 5 degrees BTDC with 32-35 full advance.

Yeah i will be going to the nats, it will be my eighth time.Cruising brice road .....what a wild weekend!

BRIAN