hi,
getting ready to order some stuff for my 9" rear end. its going into my 68' coupe with a 351w (maybe 393 stroker if i have the money for it next summer) i am going to be using a tremec tko 5 speed manual transmission in the car. the gearing for the that tranny are: 3.27, 1.98, 1.34, 1.00, .68 . after using the rpm calculator that was on this forum. which do you guys suggest for this setup, im leaning towards either 3.70:1 or 4.11:1 gears? i plan on using it as a daily driver during nice weather and also would like to be able to drag it somewhat often. what locking rear end would you suggest?

also, a local shop said that they would cut the tubes down and also get the correct length axle shafts for it and remount the spring perches for $800. this seems like a lot to me when i could take measurements myself and cut them and have a machine shop reweld the ends on. is $800 a lot?
thanks,
carl

 

Interesting. I am looking at the same question with similar equipment. My driving profile would be about the same also.

I would like to use that first gear still. I have 2.70's (at least by the tag) and still break loose the rear right easily.

Is there some way to figure out optimal ratio? Seems like 4.11 would render 1st gear un-usable.

351fox, what is your axle out of? Are you going with T-loc or Locker?

 

3.27 first makes the 4.11 useless you will be out of first before clearing an intersection.

I have a 2.8 first in my car with a 4.11 and even though I rev till 6900 to shift when racing....its a REAL short gear but I also make peak torque at 3100 so I like cruising on the highway right at 3k because I can still out accelrate most cars without even down shifting.

Personally I think you would be much happier with a 3.5 rear gear. What is the operating RPM range of your motor...which is what should be driving your choice. If you have a motor that run 2k-5500/6k...I think the 3.5 mating with the 5 speed will work far better keeping you in the power band longer and letting you cruise right around peak torque when on the highway in 5th.

 

thanks for the input,
ttoney, the axle is about 63" from drum to drum, so its out of some ford truck or bronco. i dont want a full locker, so some posi-trac differential. i havent really done much research yet.
i was thinking 4.11's would be too short, with my f250 with 4.10s and 5 speed trans i hardly ever use first gear. i dont want to run my engine much over 5500 rpm, once i get the car together i will be able to see how everything goes.
3.50's sound good to me after what you guys said.

 

351foxstang, That is pretty wide Axle. You might think about cutting it shorter than stock so you could use deeper dish rear wheels. I know my axle is out of a Lincoln and is an inch shorter on each side. Instead of changing it out I will get deeper wheels, which I like better anyhow.

As far as gearing, my motor's power band is 3,000-7,000 RPM and I like high RPM's anyhow. I am still not sure what the right gears would look like though. 3.7x or perhaps 3.8x might be really nice with a T-Loc. But I am not sure what the 450-500 F.W. HP would like best for street and very infrequently a couple of strip runs. Of course strip runs could have a taller or shorter tire to change the ratio out as well. Does anyone know what each inch or half inch does to gear ratio?


Thanks,
Tim

 

was looking again after work today, the axle came with 3.50's and they look to be in fine shape. i will try those out with whichever differential i choose.
ttoney, i like your idea of making it shorter than stock. the money saved on gears can go towards custom length Moser's. that way i can have any width i want. love the look of wide rear tires.
btw, checked out your cardomain site, your car is beautiful.
thanks for the help,
carl

 

Thanks man. Would you mind voting on my poll? I want to know what people like. It may or may not affect what I do, but I would like the input. I tried to look at your site but it seems empty. You might want a cardomain site to record your car adventures, it is easy and free. Cool features for putting the car pics on there.

What do you think of that hood?

 

voted, definately like the stripes with either of the shelby or tall scoop hoods. my car isn't worth looking at yet, pretty much just a shell. by spring time she should be rolling and completely rust free with all new suspension and brakes put in. i will get a cardomain site going once its progressed more. for now ill save all my pictures of it.