# Ford 8.8 VS. 9 Inch



## afrokng14 (Jun 27, 2009)

Hello, for my specific build I'm converting my classic 1972 Mach 1. the car came with an 8.8 rear end and if I'm not mistaken a 3.89 gear ratio. The car will be completely restored and set up to run on electric power. I plan on running a WARP11 and anywhere between 40-50 180Ah LifePo4 cells. I'm still open to suggestions for controllers even though it seems like the logisystem is in the lead for me right now; But this being my first conversion I would like some recommendations as to what to do with my rear end, transmission, and drive train.

I planned on upgrading to a 9 inch Ford and 3.55 gears when I had planned the ICE but now that I am going electric and weight and efficiency go hand and hand, does anyone have any advice? I figure now I should just pull my original rear end rebuild it with lower gears, replace the cover with an aluminum one, and still get the tru-trac for the torque of the WARP11, and still end up with a pretty stout rear with out spending too much for one that might not meet my needs originally. I'm open to all suggestions and recommendations.

Next is the Transmission, I figure I should get a JY (junkyard) T5 and have it rebuilt with the better sychros and call it a day. Where I'm lost at is should i leave the gears alone the way they are or have them geared up or down. I generally would spend most of my time in 2nd and 3rd on the roads and 3rd and 4th on the highway. 85% of the time driving is done on the roads and of course the other 15% is highway driving. Oh and I do use reverse. I read some about the power glide trannys but I dont know if that application is for me or not. they seem to be geared to chevys? 

And of course I figured I could still purchase the Aluminum drive shaft?
thanks for any assistance


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## piotrsko (Dec 9, 2007)

depends on your money / time equation and situation.

if you have lots of available funds, and aren't in much of a hurry, change everything now. recognize that every mod will pose different difficulties with adaptation and installation to some extant.

My personal mantra is get it done the quickest and worry about stuff when and if it breaks.

powerglides have race adapters for ford ICE, but in your case that would be unneccessary. the real reason to use one is: cheap, light, well documented custom applications, lot of mods and gear options and just about any tranny shop can repair or modify one.. You don't need the torque converter.

differentials are easy to modify for gear sets, so my primary ratio setting would be done there. Richmond gear has dozens of different ratios from 2.5 to 6.51. You don't HAVE to use the upper gears in the tranny if you don't need to.


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## afrokng14 (Jun 27, 2009)

piotrsko said:


> depends on your money / time equation and situation.
> 
> if you have lots of available funds, and aren't in much of a hurry, change everything now. recognize that every mod will pose different difficulties with adaptation and installation to some extant.
> 
> ...


As for money, my initial ICE budget was 40k (that doesn't mean I wanted to spend 40k, that was just my cap for the whole restoration process including engine and tranny.) But now I'm going to try and do this EV Conversion between 25K-35K. My time frame is anywhere between 1-2 years (preferably more on the 18 month side of things).

okay so is that a recommendation to upgrade to the 9inch and pick up some weight or stay with the 8.8, get it serviced and rebuilt, and get better gearing with a true-trac diff.?

I doubt any one (rear ends) will break as I plan on not racing this car but in general when you do a classic resto most go with a bigger heavier 9inch Ford rear end over the 8.8 just to deal with the massive Big Block Engines. I had planned for a 427 intially which would have kicked out over 600 RWHP and 575RWTQ but I'm not sure how much HP and TQ I would get from a WARP11 at my weight class with the battery pak I plan to use. I doubt It'll be close to my initial ICE numbers so that's why I'm not sure If I even need the 9incher now. It would be nice to get those numbers out of the DC motor but when it's all said and done I'm not sure a 3600 lbs car will still accelerate the same and get the kind of power an ICE would lay down. At least not in my first EV from what I hear others say about their first conversions.

So is this a "YES" I should look into the Powerglides, or "No" for my application I wouldn't be too efficient?

So Should I stick with the T5? and also what is the equation for figuring out the ratios for the rear end and the transmission? I have no clue how the guys on the forum come up with their numbers.


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## piotrsko (Dec 9, 2007)

afrokng14 said:


> okay so is that a recommendation to upgrade to the 9inch and pick up some weight or stay with the 8.8, get it serviced and rebuilt, and get better gearing with a true-trac diff.?
> 
> 9" is overkill unless you are going to race it, trutrac or LS is great, gearing should be done when the motor is selected.
> 
> ...


If you like the t5, then keep it. I think they are prone towards fragility, but only since my co-worker can't seem to keep any in her car for very long. 

find out the ratio of the gears in the tranny then multiple that by the ratio of the diff. say first is a 1.43 and the diff is 4.10. Overall ratio in first is 5.86.  if first was 2.0, then overall would 8.20. up side to 8.2 is you get 8 times the starting torque at the rear wheels which lowers the initial current requirements from your battery pack (kind of).


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## afrokng14 (Jun 27, 2009)

piotrsko said:


> If you like the t5, then keep it. I think they are prone towards fragility, but only since my co-worker can't seem to keep any in her car for very long.
> 
> find out the ratio of the gears in the tranny then multiple that by the ratio of the diff. say first is a 1.43 and the diff is 4.10. Overall ratio in first is 5.86.  if first was 2.0, then overall would 8.20. up side to 8.2 is you get 8 times the starting torque at the rear wheels which lowers the initial current requirements from your battery pack (kind of).


Thanks again for the info....hey were you Hinting at something with the ratio example you gave me. That just sounds terrific if you were. Normally in an ICE engine a 4.10 ratio is bad for freeway driving when coupled to a LS or Tru-Trac because RPMs are high and the car is drinking gas as if it were trying to win a contest. But with current being low that sounds like better effiecy with out the higher RPMs of an ICE and I'm not putting too much of a load on my batt pack. I'd normally stay away from a 4.10 but in this case if it would work in an EV coupled to a lighter and more efficient tranny ( powerglide ) I'll take the hint and run with it. Or was that only an example? As I said before I am open too all suggestions and recommendations.

By the way I'm going with a WARP11 and 45 cells @ 160aH or 180ah. I'd go with a WARP13 if it wasn't overkill!


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## kixGas (May 2, 2008)

wow- I read about the 8.8 vs 9" debate in my Jeep forum, Mustang Forum, and now the DIYEV forum. All I need now is for this debate be in the woodworking forum that I visit and I am all set 

I didn't read the previous responses but I would recommend sticking with the 8.8 and not changing the gears. The 8.8 is lighter than the 9" and is more than strong enough to handle the output of a Warp11. Also a T-5 should handle the output just fine. If you don't like the results and want to do direct drive then sell the T-5 and put 4:10 gears in the 8.8.
FWIW I have a T5 and an 8.8 from and Explorer in '67 coupe with a 300'ish HP 302 and I have had no drivetrain problems. Now I did blow my motor recently but that is another discussion.


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## afrokng14 (Jun 27, 2009)

kixGas said:


> wow- I read about the 8.8 vs 9" debate in my Jeep forum, Mustang Forum, and now the DIYEV forum. All I need now is for this debate be in the woodworking forum that I visit and I am all set
> 
> I didn't read the previous responses but I would recommend sticking with the 8.8 and not changing the gears. The 8.8 is lighter than the 9" and is more than strong enough to handle the output of a Warp11. Also a T-5 should handle the output just fine. If you don't like the results and want to do direct drive then sell the T-5 and put 4:10 gears in the 8.8.
> FWIW I have a T5 and an 8.8 from and Explorer in '67 coupe with a 300'ish HP 302 and I have had no drivetrain problems. Now I did blow my motor recently but that is another discussion.


I was thinking of maybe the 8.8 with L/S and a powerglide transmission. The more I read up on them the better they look. In my current car there is no transmission or engine so if I bought a brand new T5 or Powerglide the power glide would win in the weight, cost, and drivability arears. Not saying the T5 wouldn't work but in the end I want my electric vehicle to be as efficient as possible in areas of performance, range, and acceleration. I wouldn't use all the gears in the T5 plus it's pretty heavy. (would you happen to know the weight of a T5?)

Shouldn't I just go 4.10 gears from the gate without direct drive?


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## kixGas (May 2, 2008)

powerglide is a good option. I don't know for sure the weight of the T5 but I would guess it would be in the 60 lb range.
BTW you can get an 8.8 with LS (and sometimes 4.10 gears) fairly cheap. Most junkyards should sell them for $200-$300 and they don't need to be rebuilt. Just check out the mileage on the vehicle. The explorer I got mine from had 20k on it. You can also find them in late model Mustangs.


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## afrokng14 (Jun 27, 2009)

kixGas said:


> powerglide is a good option. I don't know for sure the weight of the T5 but I would guess it would be in the 60 lb range.
> BTW you can get an 8.8 with LS (and sometimes 4.10 gears) fairly cheap. Most junkyards should sell them for $200-$300 and they don't need to be rebuilt. Just check out the mileage on the vehicle. The explorer I got mine from had 20k on it. You can also find them in late model Mustangs.


Good point. My car still has the rear end in it but I don't know what type of condition it's in so since it is a 72 I figured it might need to be rebuilt for the heck of it. I'm hoping once I finally get it unbolted all it will need is just the gears, locking device, and minor servicing. But I am prepared to search ebay for some used rear ends.

What If I wanted to use 3.73 gears with this setup? would those gears decrease my performance a bit at the sacrifice of better Range with a WARP 11?


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