The voices of reason Win but still need opinions.

[my95z28]

4.10 ratio (41 teeth ring/10 teeth pinion)
4.11 ratio (37 teeth ring/9 teeth pinion)

4.11s...
http://www.neweraperformanceparts.co...&PKV=6404568|0

We aren't going to have to go through this again are we? Less pinion teeth are weaker

[9T8W66]

it will help in a roll race as much as a launch. You want close ratios in a manual so you can shift faster and harder. My car can almost finish the quarter mile in 3rd gear with the 3.42. Ryans car was. and that is not optimal when 4th is just a short step away.

Agreed since when I've run at the track I'm pulling for 4th approx 100 ft from the traps and then only spinning around 51-5200 rpm through them with the 3.42's. The steeper gears will pull harder and allow the full use of 4th so in essence making the car quicker (obviously as long as traction isn't an issue).

point taken, in that case the 3.90s should be a perfect medium IMO.

Agreed.

Heres the popular 7.5" gear sets and their teeth counts
3.23 = 42 ring 13 pinion
3.42 = 41 ring 12 pinion
3.73 = 41 ring 11 pinion
3.90 = 43 ring 11 pinion
4.10 = 41 ring 10 pinion
and for shits and giggles
4.56 = 41 ring 9 pinion

The 3.90's seem to be the best compromise IMHO
Also historically 3.90's were the basic Track Pack gears for most 4spd equipped Musclecars from BITD, Most noteably Pontiac's.

[JoeliusZ28]

We aren't going to have to go through this again are we? Less pinion teeth are weaker

yep, youre right about that. Although I still stand by less teeth being stronger, i had not taken into consideration that less teeth on the pinion increases the tendency of the ring and pinion to seperate, and therefore fail. This brings into question the strength of the housing, and unlike a Ford 9" ... ours probably isnt very strong.

I would like to see test results about this subject, as gear strength in relation to tooth count is most certainly a function moreso than it is a "more is better." There has to be an optimal tooth count for a pinion shaft given a constant diameter of the pinion.

looks like 3.90s are ftw.

[meissen]

Yeah I think that's definitely a misprint, Joel - even the picture is a 4.10 gear after counting the teeth (which isn't an easy task on a 12" laptop LCD )

[9T8W66]

Update
As of today the Car is down, Something popped in the rear or it may have been a U joint that finally started making noise. But as I was leaving work I heard a snap and then a lot more clatter. But I wasn't leaving this thing down in Taylor so I opted to baby it home from Beach Daly Rd and Ecorse to 12 mile and Harper in St. Clair shores. Tellegraph to 8 mile to Gratiot what a fun Hour and a half ride.

Looks like the rear will be getting done sooner then expected.

[Darren]

Dang Craig sorry to hear man, just rebuild the en bolt throw some better gears in it and call it a day.

[my95z28]

yep, youre right about that. Although I still stand by less teeth being stronger, i had not taken into consideration that less teeth on the pinion increases the tendency of the ring and pinion to seperate, and therefore fail. This brings into question the strength of the housing, and unlike a Ford 9" ... ours probably isnt very strong.

I would like to see test results about this subject, as gear strength in relation to tooth count is most certainly a function moreso than it is a "more is better." There has to be an optimal tooth count for a pinion shaft given a constant diameter of the pinion.

looks like 3.90s are ftw.

Yup, obviously, more material is going to equal a stronger part. But when more material leads to less tooth contact, that is when the gears become weaker. Have you ever seen an actual housing fail? I haven't. And yes, OBVIOUSLY, there is going to be a point where too many teeth, lead to thin material, and would be weaker. I would think that is common sense.

[my95z28]

Dang Craig, that sucks. I also think that the 3.90s would be the best option for you. Did it sound a bit like this? lol

[JoeliusZ28]

Yup, obviously, more material is going to equal a stronger part. But when more material leads to less tooth contact, that is when the gears become weaker. Have you ever seen an actual housing fail? I haven't. And yes, OBVIOUSLY, there is going to be a point where too many teeth, lead to thin material, and would be weaker. I would think that is common sense.

Ive seen pictures of a split 10 bolt housing, actually. Although probably not a common experience... but if gussets help them as much as they do they obviously do not resist flex under load very well.

[ThreeHonks]

yeah I was gonna say. I didnt think a 4.11 gear even existed for the 10 bolt.

[9T8W66]

4.10's dp exist but aren't really a good choice from a strength standpoint.

UPDATE
I made an apointment at Ring & Pinion on Groesbeck for Monday. So by next weekend I should be running strong with new gears and wheels and tires.

[9T8W66]

Update

Work is done turns out the gear was broken so I got 3.90 Motives new seals and bearings. It's a bit more noisy then the original stuff but well worth it.

[nascarnate326]

Im curious, what was the damage to your wallet?

[9T8W66]

Just over $800

Unfortunately I didn't have the time to order up a T/A Girdle for the car but I'll get one and have them install it in a few weeks.

[Darren]

very cool craig, excited to get it back to tip top man!