Hello folks:

Looking for some thoughts from the experts here.

I am slowly working to gather the parts to convert my 68 Barracuda to 73 style disc brakes. In order to change from the SBP to the LBP I sourced a LBP 7.25 from a 75 Dart. I am treating it basically as a core. Working on removing the rust, painting it and then taking it to be fully rebuilt. It is listed as a 2.76 open. This is exactly what I am running now only in the SBP. The car is bone stock 1bbl, 14 in wheels, A904, 9 in manual drums...etc...it’s a used for local and highway driving. I was content with the current 2.76. The axle I will be removing is in better condition than the one I am replacing it with...but I want disc brakes and a uniform bolt pattern all around. I was hesitant to get the SBP rotors as they are specific and not easily replaced at an auto parts store.

So...the question I am considering is given the stock low performance car and the type of basic driving, would there be any benefit to go to 2.93 or 3.55 gears? These ratios are readily available. I do not want something that is screaming at 65mph. I’ve read that Mopar made 2.93 part of the Super Six package years ago. Would a move from 2.76 to 2.93 be noticeable and beneficial? Highway RPM would not be drastically changed like a jump to 3.55. I cannot find 3.23. The 7.25 obviously does not have a performance following. Parts are limited compared to 8.25 or 8.75 rears. Any thoughts or Is the 2.76 the best option? Also am I completely off base with even how I am going about getting disc brakes and a uniform bolt pattern—SBP or LBP?

Additionally, any suggestions with what should be done when a 7.25 is getting rebuilt ?

Any other advise/thoughts is appreciated with the consideration of the ratios or the brake conversion (I know that should go in the other forum...)

Thanks!

If you are content with the 2.76 ratio, that answers your question. The 2.93 would be a little better IMO but not worth the money if you have to buy them and set them up.

Ditto that. If you are OK w/2.76 performance, then don't bother switching. It will be noisier on the hwy. Yep, need to buy and set up new gears too...

Lou

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Home of Slant6-powered fun machines since 1988

Likely gonna stick with 2.76. I cannot see a compelling reason to switch. I just figured now would be the time as the LBP rear is going to be completely dismantled.
The car can cruise at 60-70 MPH all day and it doesn’t feel like it’s really strained till it hits some hills.

Thanks for you responses.

I disagree with the other two. The SBP wheels are getting harder to find, and the aftermarket pickings are quite slim, should you want to dress up your car. By going to the LBP, you're opening up wheel choices quite dramatically.
By going with the 2:93 ratio, you'll lose a little on the upper end of the speed range, and slightly gain some acceleration. Neither will be greatly effected, though. You might have to run a few hundred RPM higher at 65, but that's negligible.
Your fuel economy will also suffer slightly, but you'll only notice that through actual calculation.

Oh......I see what you're asking now. Should you change the gears in the LBP, 7.25? Never mind.....I thought the LBP rear had the 2:93's, and your original had the 2:76's

Roger

I'm all for 2.93 over 2.76 IF there is no cost associated with the change. For example, if you had two complete rear end to choose from. But....no way would I bother doing it if it cost the hundreds of dollars and hours of abject, abysmal misery it requires to change a set of gears.

Is the difference great between 2.76 & 2.93 No
Is it noticeable? Yes, slightly
Is 2.93 useful performance wise for a non daily driver? Yes
Can a slightly larger rear tire compensate if needed in the future? yes and then some.
Is a 3.55 also a consideration? Not based on what you shared so far.