3rd member swap or save up for 5 speed?

[rwcstang 201]

So Im having a big issue and need some input for u guys out there.

 

Should I upgrade my 8 w/ axles (if so, which gears would be great for me?) or should I continue to save up and do a 5 speed conversion? currently im running Performance automatic Super Streeter C4 with a hughes 2500 stall.

 

thank

[SM69Mach 68]

What rear gears you running now?

 

I had a C6 and 3.25 gears behind my FE and just recently switched to a TKO 5 speed and 3.50 and it was SO MUCH more fun and with the OD drops the RPM's down enough that it isn't screaming at highway speeds.

 

I would say hold off and do the 5 speed swap, but that is just me.

[rwcstang 201]

Currently running freeway gears 2:79's

[barnett468 418]

have no idea.

 

how fast do you want to drive on the freeway and for how long do you drive there?

 

how much hp do you have.

 

your car will be faster off the line with different gears but not necessarily with a 5 speed trans.

[zudman 11]

Not sure how a 5sd will work with 2.79s, but my TKO with 3.70s turns about 1400 rpms @ 70 mph. Like SM69 said ( so much more fun )

[rwcstang 201]

have no idea.

 

how fast do you want to drive on the freeway and for how long do you drive there?

 

 

 

your car will be faster off the line with different gears but not necessarily with a 5 speed trans.

 

 

 

I do drive on the freeway alot especially to work (rouchly takes 15-20 mins drive). I don't go that fast, i stick around 65-75 or keep up with cars next to me since my speedometer isn't really accurate, but got pinged for doing 92 yesterday, Happy NYE to me! :taz:

 

anyways, rpm's of course are really high, but no RPM tach to see where they stay at when I'm on the freeway.

 

As for HP, Ford performance solutions said the build I have should be around 450, I've ridin in 400hp+ cars but they were all manuals, so I "feel" limited with my c4 and rear end gears.

 

I do want a 5 speed, but everytime Im about to be close on buying the transmission I want, they hike up the price.. sucks...

[DRASTiK 22]

In a perfect world, you'd do both at the same time. My opinion - since you need to do them one at a time, if you do a gear swap to work with the C4, and later perform the 5 speed conversion, you'll likely end up doing another gear swap to better fit the 5 gear transmission. I'd do the trans conversion first, then do the gearing later.

[barnett468 418]

.

Depending what your engine revs to, in general, imo/guess, 3.23 - 3.40 gears with your 2500 stall converter would likely be a good compromise for you if you can live with only 68 - 70 mph on the freeway for longer drives.

 

Unless you have a serious need/desire to roast the tires every time you start and are not looking for a massive increase in acceleration, then i would go with the 3.23 . . The difference will be fairly noticeable and will feel like you have a 331 engine instead of a 302 . . 3.40 will make it feel like a 351 enf.

.

Edited January 2, 2015 by barnett468

[maxum96 32]

I run a TKO with 4.11 gears with a 28" tall tire. At 60mph I'm turning around 2200 rpm. Nothing like running a modern OD transmission in a vintage muscle car.

[barnett468 418]

I do drive on the freeway alot especially to work (rouchly takes 15-20 mins drive). I don't go that fast, i stick around 65-75 or keep up with cars...

 

rpm's of course are really high, but no RPM tach to see where they stay at when I'm on the freeway.

your rpm can not be really high at 70 with 2.79 gears unless you are in second.

 

 

 

As for HP, Ford performance solutions said the build I have should be around 450, I've ridin in 400hp+ cars but they were all manuals, so I "feel" limited with my c4 and rear end gears.

i seriously doubt that the 400 hp cars you rode in were running 2.79 gears and if they weren't then of course they would feel faster.

 

 

 

 

I do want a 5 speed, but everytime Im about to be close on buying the transmission I want, they hike up the price.. sucks...

well. if you don't beat the bejesus out of it you can buy a used t5 out of an 87 [i think] and later 6 or 8 cyl . . it is called a "world class", then get it rebuilt . . i personally hate the gear ratios in those though and prefer the ratios in the 600 trans . . the prob is they are typically new only so they are pricey, also they are a bit taller than the t5 so your drive shaft angles won't be ideal but you can improve them if you run lowering engine mounts which will magnify any vibration you have.

[1969_Mach1 333]

Don't have any input at this time. But with your current setup I hope your RPM is over 2500 when you are cruising down the freeway. If not, your trans will be running hotter than it should.

 

In the long run, you will probably need both a different rear axle gear and trans for the driving type you are doing with this car. I think I would save, if you can, then swap out the 8 inch for a 9 inch as part of the change over.

Edited January 3, 2015 by 1969_Mach1

[maxum96 32]

Don't have any input at this time. But with your current setup I hope your RPM is over 2500 when you are cruising down the freeway. If not, your trans will be running hotter than it should.

 

 

A 2500 stall converter only stalls that high when you are holding the car still and pushing on the throttle. It will not stall that high during normal driving. I ran a 4000 rpm converter on the street in a C6 years ago. But high stall converters do make more heat period. But they can be run on the street with add on trans coolers. A 2500 stall converter is not that extreme of a stall converter at all.

[1969_Mach1 333]

You might be right maxum96. I was just speaking from what I learned in a transmission course a long time ago when I was a GM tech.

 

I live in northern California as well. One thing is for sure, commutes are brutal on any car.

[j69302 11]

Not sure how a 5sd will work with 2.79s, but my TKO with 3.70s turns about 1400 rpms @ 70 mph. Like SM69 said ( so much more fun )

 

Did you mean 2400 rpms? No way you are spinning 1400rpm at 80 with 3.70s unless you have some monster truck tires!

 

I have a TKO with 2.79s and am very happy with it, however, in hindsight, getting the "roadrace" .82 overdrive instead of the standard .63 would have been better as I plan on keeping the 2.79's.

 

I have 245/60/15 tires (26.6 inches tall) and at 80mph is 1800 RPMs, which is nice, but I don't do 80mph very much and the other road race overdrive gearing would be better.

 

I have a mild 302, and as long as I am at 65 or higher, it cruises in 5th just fine. Anything below that its best to used 4th, however, with 450hp like the OP plans on putting it, I bet it would be really nice.

 

To the OP-

 

You need to decide on what you are going to be doing. I just cruise, so I like the 2.79s and the super overdrive(put I would prefer the roadrace .82 overdrive instead), I get 45-50 mph at 5000 rpm out of first gear. I can do normal starts in second gear just as easily as first. If you have cruising in mind, I think you will want to stay under a 3.25 rear end. Anything lower (higher numerically) than that, you could just not even use 1st or 2nd for normal driving lol.

 

 

Check out the attatched file, a Excel spreadsheet to compare a baseline Transmission/Wheel/tire size, vs 2 others.

 

Only changes the items in yellow, all non-yellow cells are formulas.

Edited January 3, 2015 by j69302

[zudman 11]

My eyes are not that good anymore but, It looked like 1400 to me..(lol) With .64od, 3.70 gears, 255/60/15 (27.1 tall) tires..Ballpark, what should it be turning @ 70 mph. ?

[SA69mach 39]

I think a solution to your two concerns would be to dump the 8 inch for a 8.8 inch rear end out of an Explorer, and a stock T5 from 84-92 Mustang V8.

 

Those items are generally easy to find and cheap. I got both mine off craigslist in less than a week, in 2013. You get tru-trac, 3-73 gears, disc brake rear. 5 speed with overdrive transmission that bolts right up to your 302.

 

There is some work to be put in to get it done. New shock mounts welded on the rear end. New cable for the parking brake. New flywheel and clutch. Adapter plate of some work on the bellhousing for the clutch fork. New clutch pedal - although you have the choice of Z-bar, hydraulic or cable. (I don't like cable) Some work or a new driveshaft. Probably at least one new axle and a shortening job on the rear end.

 

I have done all of those things and it is pretty straightforward. I am no great mechanic. You will be happy with the cruising revs and speed with an overdrive, and still very good performance around town with the first four gears. 3.50 gears would be my perfect choice, but you get a great center with the 8.8 inch Explorer diffes, so I am not complaining. Tough units.

I have got some fairly hard running out of my second hand T5 with zero money put into it and zero problems. Over 5000 miles so far.... Tough unit too. If you load them up with big horses, and big torque, and beat on them, then....they will break. But doesn't everything? They are light, cheap and seem to be plenty around.

[det0326 179]

I think a solution to your two concerns would be to dump the 8 inch for a 8.8 inch rear end out of an Explorer, and a stock T5 from 84-92 Mustang V8.

 

Those items are generally easy to find and cheap. I got both mine off craigslist in less than a week, in 2013. You get tru-trac, 3-73 gears, disc brake rear. 5 speed with overdrive transmission that bolts right up to your 302.

 

There is some work to be put in to get it done. New shock mounts welded on the rear end. New cable for the parking brake. New flywheel and clutch. Adapter plate of some work on the bellhousing for the clutch fork. New clutch pedal - although you have the choice of Z-bar, hydraulic or cable. (I don't like cable) Some work or a new driveshaft. Probably at least one new axle and a shortening job on the rear end.

 

I have done all of those things and it is pretty straightforward. I am no great mechanic. You will be happy with the cruising revs and speed with an overdrive, and still very good performance around town with the first four gears. 3.50 gears would be my perfect choice, but you get a great center with the 8.8 inch Explorer diffes, so I am not complaining. Tough units.

I have got some fairly hard running out of my second hand T5 with zero money put into it and zero problems. Over 5000 miles so far.... Tough unit too. If you load them up with big horses, and big torque, and beat on them, then....they will break. But doesn't everything? They are light, cheap and seem to be plenty around.

 

On the explorer rear end did you do the typical cutting of the long side and using another short side axle. If so didn't that still leave the pinion offset 1 inch?

Dave

[j69302 11]

My eyes are not that good anymore but, It looked like 1400 to me..(lol) With .64od, 3.70 gears, 255/60/15 (27.1 tall) tires..Ballpark, what should it be turning @ 70 mph. ?

 

Mathematically your engine rpm at 70 mph in od will be 2059. 80mph is 2353

 

What it should be depends on your engine. My engine really like 2000-2500, which is not where it's at right now for my combo.

[SA69mach 39]

On the explorer rear end did you do the typical cutting of the long side and using another short side axle. If so didn't that still leave the pinion offset 1 inch?

Dave

 

I built the rear end 3 inches shorter than stock, overall. So, trimmed both sides, and two new forged axles required for my application. Still worth the rest of the parts with that rear end, in my opinion. No offset with the work done.

I don't think a one or even two inch offset is a problem anyhow. They are designed for a lot more than two inches up and down, so two inches side to side is negligible.

[barnett468 418]

I built the rear end 3 inches shorter than stock, overall. So, trimmed both sides, and two new forged axles required for my application. Still worth the rest of the parts with that rear end, in my opinion. No offset with the work done.

I don't think a one or even two inch offset is a problem anyhow. They are designed for a lot more than two inches up and down, so two inches side to side is negligible.

 

hi SA69mach;

 

actually the pinion should be centered . . running then off center can cause premature wear to the u joints and vibrations . . if you take the short side axle and tube out of another 8.8 and replace the long ones in the unit you are using with them, the pinion will be perfectly centered.

.

[SA69mach 39]

Disagree. I ran that 8.8 off center for over a year , then did the shortening and evening up job for some deep dish wheels. Never had any problems with it off center, or centered.

So, even though it would be nice to have it all perfectly centered, my opinion, based on actual experience with both situations, is that it made no difference, and caused no problems.

Plenty of cars have the pinion slightly off center by accident, not design. The universal joint is designed to manage this situation. The uni joint does not know what plane the offset occurs.

These 8.8 inch conversions have been done for years, with great success and satisfaction. For a street car, they are fine, even with some static offset. even 2 inches over the 52 inch length of a driveshaft is quite minimal, and within tolerance for the universal joints.

 

Have you experienced problems with an 8.8 inch that you have installed? If not, then try it before you advise people to spend a lot of time and money changing out axle tubes and axles so it fits your ideal.

 

It works fine with 1 inch offset. it works fine with zero offset. What else can I say. The question was asked what did I do. Address your advice to the original poster, not me. I am perfectly happy with my 8.8 inch.

[det0326 179]

Disagree. I ran that 8.8 off center for over a year , then did the shortening and evening up job for some deep dish wheels. Never had any problems with it off center, or centered.

So, even though it would be nice to have it all perfectly centered, my opinion, based on actual experience with both situations, is that it made no difference, and caused no problems.

Plenty of cars have the pinion slightly off center by accident, not design. The universal joint is designed to manage this situation. The uni joint does not know what plane the offset occurs.

These 8.8 inch conversions have been done for years, with great success and satisfaction. For a street car, they are fine, even with some static offset. even 2 inches over the 52 inch length of a driveshaft is quite minimal, and within tolerance for the universal joints.

 

Have you experienced problems with an 8.8 inch that you have installed? If not, then try it before you advise people to spend a lot of time and money changing out axle tubes and axles so it fits your ideal.

 

It works fine with 1 inch offset. it works fine with zero offset. What else can I say. The question was asked what did I do. Address your advice to the original poster, not me. I am perfectly happy with my 8.8 inch.

 

Hello SA69mach

 

I was just curious how you did yours? I thought about this swap for a long time as to which would be the best way to do it. I was initially going to do the shorten of the long side too and use another short side axle on the long side then found that that would still leave the pinion offset by 1 inch to the other side. So what I did, really wanting to keep the stock width, is I cut from the brake caliper mounting flange back 7" on the long side and did the same on the short side except I cut it 5" then switched the two and and using an alignment gauge welded back on. As you say though I had to have custom made axles but this put the pinion in the center. Thanks for your input and sorry for the thread hijack but thought this was a good place to ask this question.

Dave

[SA69mach 39]

No harm.

There are a lot of ways to shorten the 8.8, it all depends on where you decide to cut the tubes. Whatever length is decided, the axles must be made to fit.

I used Dutchman axles. Moser and Strange make good stuff too. The Moser axles in their kit are made longer with long splines specifically to be cut to size.

 

Other issues relating to the offset have already been discussed.

 

The use of a plasma cutter is almost essential and some very careful alignment when re-welding is absolutely necessary. Solid welding is also crucial. That is about it. The 8.8 has some excellent features, namely trutrac center, and disc brakes. Cutting away the tube sections to make them fit your purpose is all about how much work you are willing to do and what your goals are.

The average vintage Mustang can be well served by the standard process of cutting the 'long' side tube and living with an inch offset. if it clears the exhaust I say it is no problem. The 'problem' in my opinion, only arises if there is interference with the trans tunnel or the exhaust pipes.

 

I did this work on my 8.8 in a professional shop in California under the direction of the proprietor and very experienced hot rod builder. Not sure if I would tackle it as a home job without a big upgrade to my tool chest.

[barnett468 418]

Disagree. I ran that 8.8 off center for over a year , then did the shortening and evening up job for some deep dish wheels. Never had any problems with it off center, or centered.

So, even though it would be nice to have it all perfectly centered, my opinion, based on actual experience with both situations, is that it made no difference, and caused no problems.

Plenty of cars have the pinion slightly off center by accident, not design. The universal joint is designed to manage this situation. The uni joint does not know what plane the offset occurs.

These 8.8 inch conversions have been done for years, with great success and satisfaction. For a street car, they are fine, even with some static offset. even 2 inches over the 52 inch length of a driveshaft is quite minimal, and within tolerance for the universal joints.

 

It works fine with 1 inch offset. it works fine with zero offset. What else can I say. The question was asked what did I do. Address your advice to the original poster, not me. I am perfectly happy with my 8.8 inch.

 

There are more than one factor to consider and I have experience with way more than just one axle . . I also did not say that it would always, definitely, cause a vibration or U joint damage, and the info was actually intended for the op.

 

...running then off center can cause premature wear to the u joints and vibrations.

 

 

 

Have you experienced problems with an 8.8 inch that you have installed? If not, then try it before you advise people to spend a lot of time and money changing out axle tubes and axles so it fits your ideal.

Ford and the other mfg's put it on center or close to it, therefore it it fit their ideal before it fit anyone else's . . It is best to be on center.

 

 

If one runs an aftermarket trans that changes the driveline angle, it can be worse than running it off center with a stock trans . . If it has to be shortened anyway, it seems practical to me to simply do it right instead of doing it wrong . . That being said, 1" is not a lot, and in some instances is not a big concern, but I have seen some off center by more than that and it has caused problems in some of those instances.

 

I have also seen many cars with the pinion in line but the driveline angles incorrect due to the addition of after market trannies that had a vibration due to this.

.

Edited January 5, 2015 by barnett468

[SA69mach 39]

OK, well, I have been told. Thanks.

 

Working within a reasonable budget and tolerances is not "deliberately doing it wrong"

Having run this set up for an extended period and over 3000 miles without any issues does seem to point to it being a reasonable solution when searching for a cheap rear end upgrade.

I would leave it up to the individual to assess and measure the cost/benefit of the 'easy' alteration of the 8.8 inch. My experience proves that it can work, and without any further problems. That is what I offered the OP and subsequent posts. Not a lecture on how it should be done "right' according to your own standards.

My suspension builder is not an idiot, he has built hundreds of rears for race cars, hot rods and drag cars. Hundreds. As in, 'way more than you' He said it would be fine with 1 inch offset, and he was, and remains, "right" too. Touche Barnett. As one of the very few members here who rallied against your banning, I am bemused, but not amused by your mini tirade about this. Please quit this back and forth and let people have different opinions to yours... it does you no favors to harp on pointless issues.