I have been wanting to step up to a Dana for a long time. It sure is Purdy under my car too . I hope I can get that performance back but if I don't I know I can spray my way into some numbers without worries of carnage. I am ready to try a little N0S on the car pretty soon.

How is it possible to add weight to a car and not change something.

If your reply is "because of adding weight to the correct place", then that means if we could add the entire weight of the car to that perfect spot we could get unlimited acceleration?

If the answer is more efficient, then why aren't al rears constructed that way to save on gas?

How does this work?

There may be about 30-50lbs difference which can account for .05 in ET, but the efficiency of a Dana 60 over an 8 3/4 seems to normally makes up for it. I know a few Stock class racers who have switched like you and have seen no difference. But they do normally readjust the overall car weight back down to near class minimum. Of the most popular rears, a 12 bolt is most efficient while a Ford 9" is the worst. I would guess that GM 10 bolt may be more efficient, but it wasn't in a detailed magazine article I saw years ago.

For those reasons, I installed a Dana 60 in a low 12 second Aspen wagon. I'm confident that I didn't lose any overall ET, but wasn't able to establish a baseline and get more detailed info because of ongoing Thermoquad tuning issues.

Track timing can vary also. I've been to tracks where the difference in front tire pressure was 50+ at one track and 28 at another to get the same RT's, and possibly RPM adjustments too!. That's just the starting line. 1/8 and 1/4 mile can be a bit different too.

My dad swapped from a 8 3/4 to Dana 60 in his duster back in the late 90's and lost a tenth. If I recall correctly both rears had a posi and he used the same brakes on both. I don't see how adding weight to your car won't slow it down atleast a little.

Being you ran one track in March and another in Sept, that could be a HUGE difference. I know racing difference tracks even on the same weekend can produce difference results. Not typically a tenth difference, but there will be subtle differences. One timing system could be 1320.1 ft and one could be 1319.9 ft. My dad raced late weekend and again yesterday. He was .05 slow yesterday in the 1/8 compared to the weekend before. 60ft was the same but was down 2 mph...air wasn't real great yesterday.

If I’m not mistaken Richmond is shorter than the Beach. That said you changed a lot of things, temp is different and traction is bound to be different between tracks. Way to many variables. We would go to the Duck, Beach and Manassas and never ran the same number. Also that spacer can make a big change.

Wait another month or so and try again. I've seen 3+ tenths and 4 mph change from good air to bad summer air.
My car wasn't affected at all by the switch to a Dana from an 8.75...except it doesn't eat ring and pinions anymore. I made the switch back when it was a mid 10 sec 3700 lb car FWIW.

Hopefully I can find my numbers again. Darn shame I don't race anymore , I just chase numbers . looking for that new best. There really is something wrong with my brain. LOL Putting the Spray on it now "100 Shot" just to try and find a little more ET.

200 shot is easy and fun..

Why not race anymore.
You can just as easily find out how fast your car is even bracket racing.
I have my foot to the floor in time trials.....i am chasing numbers.
Then i put a dial on it, and if my competitor goes red, i chase numbers again. 98% of drag racing to me is beating the other guy.

I agree with you, but I think we're becoming the minority anymore.......seems nowadays most are chasing the "whoomp-whoomp" at the end.

Tracks make a difference. Capitol and VIR are at least 1 tenth faster than other tracks I have raced at here in Maryland.

Got bored just chasing numbers. I like the challange of bracket racing. Either setting it to go on index by slowing it a bit. Or running it flat out with a dial. It's ll about turning on the win light and going rounds for me.
Doug

Doug.... you going to BG this weekend?

No, I'll be at Milan for GLSSA. 1 hr drive and $2K to win. Next weekend NMCA at Indy
Doug

I really enjoy bracket racing too, Just suck at it. LOL . These guys that can cut .00 lights right off the foot brake and run dead on there number are tough to run with. I have turned into a 1st round duck a lot over the years. It is fun to go rounds, I think . It's been so long since I have.

We just put a dana in a 318 dart after if killed a ring and pinion on the 8-3/4, with around 60 passes. Best et was 7.21 at 94mph. Put in Dana 60 with same 4.10 ratio and went 7.12 at 94mph. So................