Axle and spline count recommendation for a drag car?

[cjshaker]

I wasn't aware that the 35 spline took a larger bore center housing. Since I was planning on buying a separate center case anyway, and leaving my old one complete for street duty, I'll just step up to the 35 axles and the bigger center for its future use in another car and build this one with the 31s and a higher gear for the Mustang and next years Reunion.

Thanks everyone for the great info and feedback.

[Posi67]

M/W 35 spline in my car with 5/8ths drive studs. !0 years and never a problem but it's been two seasons since I've had them out. I'm considering buying a spare set although not sure if I'll ever need them. Keep in mind that M/W has their own spline configuration and you have to run their spool. Not sure on the Masterline Series so calling them wouldn't hurt.

Funny what they told Jay. When I called about parts I was told I should go with the 40 spline Pro Mod setup. Serious overkill for my junk.   

[Falcon67]

I think you can go 35 without having to change the housing ends.  If you're going to buy a new set of axles and a new diff, I think I'd go as big as possible.

Yup, I think there are bearings that will let you use the 35 spline axles with the small housing ends but he already has the big housing ends.

Usually 31 and 35 are the same price.  The deal is that with 31s you can keep your locker, otherwise you're out that expense too if you up the spline count.  As noted above.

[mike7570]

Keep in mind that M/W has their own spline configuration and you have to run their spool. Not sure on the

Some pics of rear I pieced together using Currie 35 spline (they can do a MW spline) I'm using MW spool, Strange large case, Large housing ends (recommended for 35 spline) ball bearing support motive REM finished gears.

[cjshaker]

M/W 35 spline in my car with 5/8ths drive studs. !0 years and never a problem but it's been two seasons since I've had them out. I'm considering buying a spare set although not sure if I'll ever need them. Keep in mind that M/W has their own spline configuration and you have to run their spool. Not sure on the Masterline Series so calling them wouldn't hurt.

Funny what they told Jay. When I called about parts I was told I should go with the 40 spline Pro Mod setup. Serious overkill for my junk.

I saw that about their spline design, so yeah, I'll have to call them. I won't be using a spool though, I want to stick with a locker so I can at least drive it occasionally to a couple of local events.

I had to look back at my paperwork and remembered that Currie had some supply issues when I bought my rear 17 years ago. They supplied me with Strange axles, so that relieved any doubts I had about that. Now I'll just build the extra center section with higher ratio for the Mustang and concentrate on another rear with 35 spline for another project.

[Nightmist66]

What ratio are you thinking of going to Doug?

[cjshaker]

Since this is in the Mustang and only for fun at the FE Reunion, and I don't have a rollbar or subframe connectors, I've got to take it a little easy on it. I've been playing with some of the calculators online and not knowing what the car will run or its speed makes it a guess, but to get the most out of the car would probably take something like a 4.56. I don't want to wind the engine past 6500 though so I'm leaning towards the 4.33s. For the other project, with a heavier car and a lot more engine, I'll probably need something around the 4.80 area.

[Nightmist66]

I love the 4.33 in mine. Miles per gallon? Nah, it's smiles per gallon! When I finally got my car to the track this fall, it was going through at about 5600@104mph. This was with a 27in drag radial. I was launching around 3k. I will be installing my new subframe connectors before I head back in the spring and will get a real set of slicks and launch harder and see what happens.

Here is what I like to use to calculate things- http://www.summitracing.com/popup/calcsandtools/gear-ratio-calculator

[Falcon67]

>Keep in mind that M/W has their own spline configuration and you have to run their spool.

Not so on the Masterline axles, at least my 31 spline parts.  I've run Moser and Strange spools along with the Trac-tech soft locker that is in the car now. 

[cjshaker]

>Keep in mind that M/W has their own spline configuration and you have to run their spool.

Not so on the Masterline axles, at least my 31 spline parts.  I've run Moser and Strange spools along with the Trac-tech soft locker that is in the car now.

Yes, according to MW, the 31 spline will work with standard lockers. I believe they also offer custom machining on their other axles, so that may be an option I have to go for. I'll have to call to verify that though. I really don't want to go with a spool.

[Nightmist66]

What size tire are/will you be using?

[cjshaker]

The Mustang uses MT ET Streets, 28" tall. I'm curious, do you know approximately how much HP your engine makes? I've ran a few GPS based 1/4 mile runs with basically no traction taking off and supposedly ran over 100mph. I don't put much stock in the accuracy though. Honestly, I'd be happy to hit mid 12s and not twist the frame

[Nightmist66]

The Mustang uses MT ET Streets, 28" tall. I'm curious, do you know approximately how much HP your engine makes? I've ran a few GPS based 1/4 mile runs with basically no traction taking off and supposedly ran over 100mph. I don't put much stock in the accuracy though. Honestly, I'd be happy to hit mid 12s and not twist the frame

Well, it has never been dynoed. The motor was a mild rebuild about 25yrs ago and is a little wheezy now I think. Maybe 10.2-10.3:1, .030 over, mild hyd. flat tappet. By the Moroso slide calc. I have, at a solid 3750-3800lbs, I figure probably around 4-415ish hp? I should have enough if the stars are aligned to get mid twelves. I wouldn't worry about twisting the frame. However, mine shows signs of harsh racing in the past with a healthier setup around the rear wheel lips and back quarter windows, there is some cracking in the paint. I need to get the subframe connectors in to stop this. Most obvious on a stick car. I ran out of time this fall to get them in with the hydramat ordeal, so I just ran it anyway. I wanted to get to the track the last two years but kept having things come up.

[Falcon67]

I love the 4.33 in mine. Miles per gallon? Nah, it's smiles per gallon! When I finally got my car to the track this fall, it was going through at about 5600@104mph. This was with a 27in drag radial. I was launching around 3k. I will be installing my new subframe connectors before I head back in the spring and will get a real set of slicks and launch harder and see what happens.

Here is what I like to use to calculate things- http://www.summitracing.com/popup/calcsandtools/gear-ratio-calculator

Before you run off and buy "a real set of slicks" note that a lot of us "real slick" users are switching to Drag Radials.  Switching from M/T 3055 28-10.5x15 slick to a Hoosier 275-60-15 DR lowered my 60' by about .05 with the 302.  When we bolted them on the Mustang it picked up a full tenth ET in the 1/8 mile and almost 1 MPH.

[jayb]

Drag radials are great - as long as you maintain good traction.  If you start spinning them, they will not re-hook like a regular slick will.  I tried a set on my Galaxie in 2009, same size as my regular slicks (10.5-29.5/15), and could not get them to hook no matter what I did.  Of course, the car hooks great with the regular slicks (see my signature pic).  Despite their advantages (less rolling resistance, typically higher MPH at the end of the track), there are drawbacks too...