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Offline 65ShelbyClone

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Power/torque limits of a stock 6.75in rear end?
« on: July 10, 2014, 02:11:27 PM »
Predictably and unfortunately, my 2.3T/T-5 swap has gone over budget and the drop-in Pinto 8in rears I am finding will consume an uncomfortably large portion of what remains. This has me thinking about trying to nurse it along on the stock 6.75 rear for a while so the car can at least be driven. Keeping the stock appearance for awhile will be fun too.

The non-intercooled 2.3T I have was originally rated at 155hp/180ft-lbs at 14-15psi.

It can also be run at a lower ~9-10psi, which I estimate will drop output to about 130hp/150ft-lbs.

Assuming I never dump the clutch (which I never really do anyway), only roll-on the throttle, granny shift, and overall treat it gently, do you all think a 6.75 would tolerate that for some time?
'72 Runabout - 2.3T, T5, MegaSquirt-II, 8", 5-lugs, big brakes.
'68 Mustang - Built roller 302, Toploader, 9", etc.

Offline cromcru

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Re: Power/torque limits of a stock 6.75in rear end?
« Reply #1 on: July 10, 2014, 08:09:40 PM »
as long as you keep up good maintance on the rear end it should be fine.im doing 2.3 efi/t5/6.75 and having no problems so far
79 bobcat  78 ford pinto station wagon   93 ford mustang lx   90 ford mustang cont lx  63 chevy truck    52 studebaker 2r16a

Offline amc49

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Re: Power/torque limits of a stock 6.75in rear end?
« Reply #2 on: July 12, 2014, 04:40:46 AM »
I'd run synthetic lube to carry more load.......... .....

Offline Wittsend

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Re: Power/torque limits of a stock 6.75in rear end?
« Reply #3 on: July 12, 2014, 11:16:08 AM »
 "- has gone over budget and the drop-in Pinto 8in rears I am finding will consume an uncomfortably large portion of what remains."

It seems you are located in Lancaster, CA.  This is not too far from the self serve yards in Sun Valley. I had posted back in June that there was a Mustang II with a 8" rear in their Primo yard. This was during their 50% off sale.  You could probably have gotten that rear end for $75 at the sale. Their regular price for a drum to drum rear end is $129.99 with a $15 core charge. The Primo yard (the only place they now have older cars) charges about 30% more.  Sadly there are no posted prices for exact costs.  I can't guarantee you will find the rear end on any trip, but you should be able to acquire the rear end in time without breaking the bank.

 As far as using the 6-3/4" if you drive as you state it will probably hold up.  The greatest torque force is just prior to the tires breaking loose. Avoid that and it should survive.  With a turbo car I find that gradually applying power causes more appreciation for the acceleration forces than just nailing the throttle which is dependent upon the turbo spooling up.  When I give people rides I generally drive the car "normally" stating that this is the way a regular Pinto runs. The next time I go through the gears I'll shift into 3rd and gradually push the pedal down.  You can see their eyes grow large when it feels like an afterburner has kicked in!

Offline 65ShelbyClone

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Re: Power/torque limits of a stock 6.75in rear end?
« Reply #4 on: July 12, 2014, 03:41:43 PM »
I'm not worried so much about it wearing out as I am about parts breaking. The non-EDIS EFI 2.3s were only rated at 88hp

Maybe I'll fill it with 85w-140 lube for a little extra cushion. No doubt that what's in it is ancient and foul and needs to be changed anyway.

"- has gone over budget and the drop-in Pinto 8in rears I am finding will consume an uncomfortably large portion of what remains."

It seems you are located in Lancaster, CA.  This is not too far from the self serve yards in Sun Valley. I had posted back in June that there was a Mustang II with a 8" rear in their Primo yard. This was during their 50% off sale.  You could probably have gotten that rear end for $75 at the sale. Their regular price for a drum to drum rear end is $129.99 with a $15 core charge. The Primo yard (the only place they now have older cars) charges about 30% more.  Sadly there are no posted prices for exact costs.  I can't guarantee you will find the rear end on any trip, but you should be able to acquire the rear end in time without breaking the bank.

I may have to resort going to a wrecker. The only Pinto 8" I have found recently had a $250 price tag on it (plus another $23 in tax) and that was from a yard, although it had already been pulled. Same thing for '65-66 Mustang and MII 8" rears; bottom line seems to be about $250 for a complete one of unknown condition. >:(

I already have a complete 8" rear end with a 3.00s, but it's out of my '68 Mustang, so it's 59" wide and five-lug. I wanted to modify and use the 7.5" T-lock with 3.45s out of my '86 'Bird donor, but that thing is 61" wide and not at all worth shortening nor using wheels with the requisite 5.5in+ offset.

Quote
As far as using the 6-3/4" if you drive as you state it will probably hold up.  The greatest torque force is just prior to the tires breaking loose. Avoid that and it should survive.

It should help that I'm going to leave the stock wheel/tire setup until the tires are spent. They are just Chinese 195s and I doubt the tread is wider than four inches.

Quote
With a turbo car I find that gradually applying power causes more appreciation for the acceleration forces than just nailing the throttle which is dependent upon the turbo spooling up.  When I give people rides I generally drive the car "normally" stating that this is the way a regular Pinto runs. The next time I go through the gears I'll shift into 3rd and gradually push the pedal down.  You can see their eyes grow large when it feels like an afterburner has kicked in!

I used to have an '84 Mustang SVO and the 2.3T is definitely fun. ;D Even in a car 1000lbs heavier than a Pinto, they have some pep. The throttle is progressive so it's deceptively unresponsive at low throttle, but opens very quickly after ~50%. A previous owner had put an E6 manifold on mine, so that helped boost response and was probably worth about 15hp.

'83-86 2.3Ts have one of the largest turbos I know of ever put on a mass production engine. The IHI they switched to was probably a good choice for the heavy chassis, but the whistle and abrupt onset of boost and power that larger turbos have is why I like turbo cars.
'72 Runabout - 2.3T, T5, MegaSquirt-II, 8", 5-lugs, big brakes.
'68 Mustang - Built roller 302, Toploader, 9", etc.

Offline dick1172762

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Re: Power/torque limits of a stock 6.75in rear end?
« Reply #5 on: July 12, 2014, 03:51:06 PM »
Don't worry about it because all your going to do is spin one tire as long as you have your foot in it.
Its better to be a has-been, than a never was.

Offline ricohman

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Re: Power/torque limits of a stock 6.75in rear end?
« Reply #6 on: July 13, 2014, 12:08:49 PM »
I ran a 302 with the open stock diff in my 72'. It would send one wheel up in smoke but I never killed the diff. And when I was 19 I didn't drive it easy.

Offline 65ShelbyClone

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Re: Power/torque limits of a stock 6.75in rear end?
« Reply #7 on: July 13, 2014, 01:15:11 PM »
Well that's reassuring. Thanks for the input everyone. I guess I'll take it easy and not worry about it too much.
'72 Runabout - 2.3T, T5, MegaSquirt-II, 8", 5-lugs, big brakes.
'68 Mustang - Built roller 302, Toploader, 9", etc.

Offline 65ShelbyClone

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Re: Power/torque limits of a stock 6.75in rear end?
« Reply #8 on: August 01, 2014, 11:40:45 PM »
It seems you are located in Lancaster, CA.  This is not too far from the self serve yards in Sun Valley. I had posted back in June that there was a Mustang II with a 8" rear in their Primo yard. This was during their 50% off sale.  You could probably have gotten that rear end for $75 at the sale. Their regular price for a drum to drum rear end is $129.99 with a $15 core charge. The Primo yard (the only place they now have older cars) charges about 30% more.  Sadly there are no posted prices for exact costs.  I can't guarantee you will find the rear end on any trip, but you should be able to acquire the rear end in time without breaking the bank.

This is just my personal account.....

I spent several hours at LKQ today because they have a 50% off sale going now, but the "primo" yard wasn't open at alll. Gate was closed and locked.  ???

All I ended up getting was a 3G alternator and a few bits of wiring. My gas was $24, parts $28.  It was a fun 120mi round trip with a few hours of 100F heat in the middle.  >:(
'72 Runabout - 2.3T, T5, MegaSquirt-II, 8", 5-lugs, big brakes.
'68 Mustang - Built roller 302, Toploader, 9", etc.

Offline Wittsend

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Re: Power/torque limits of a stock 6.75in rear end?
« Reply #9 on: August 02, 2014, 12:30:49 AM »
I was at the Sun Valley LKQ (Pick Your Part) yard on Friday, 8-1-2014. I assume since it was the first day of the 50% off sale it was the "today" you are speaking of?  I arrived just before they opened at 7AM and left about 9:30AM.  The Primo yard was open when I was there. Here is my link to my account of the day (not all that inspiring either).  http://www.fordpinto.com/general-pinto-talk/two-styles-of-steel-rallye-wheels/msg151941/?topicseen#new

There were three Mustang II's in the Primo yard. One was a 8" 3.00.  Another was a 6-3/4" and not sure about the third.  Sorry it didn't work out for you. Can't understand why the Primo yard was closed. I've never seem that happen.

Offline 65ShelbyClone

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Re: Power/torque limits of a stock 6.75in rear end?
« Reply #10 on: August 02, 2014, 10:42:14 AM »
I was at the Sun Valley LKQ (Pick Your Part) yard on Friday, 8-1-2014. I assume since it was the first day of the 50% off sale it was the "today" you are speaking of? I arrived just before they opened at 7AM and left about 9:30AM. The Primo yard was open when I was there. 

Yeah, I was there yesterday (Aug 1) too, but I didn't arrive until about 12 and was nearly heat-stroked by the time I left.

The last time I was at that junkyard must have been 2001-2002, so I didn't really know my way around. Maybe I just couldn't find the primo entrance, but I assumed it was the double gates under a very large sign that read "Primo Yard Entrance."

Quote
There were three Mustang II's in the Primo yard. One was a 8" 3.00.

Man, I would have pulled that diff the second I saw it. No question.

I can also try the LKQ yard in Bakerfield. It is only four miles further than the one in Sun Valley and the drive is far nicer, but then I don't have any other eyes on the ground telling me where to look.  ;)
'72 Runabout - 2.3T, T5, MegaSquirt-II, 8", 5-lugs, big brakes.
'68 Mustang - Built roller 302, Toploader, 9", etc.

Offline Wittsend

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Re: Power/torque limits of a stock 6.75in rear end?
« Reply #11 on: August 02, 2014, 06:12:33 PM »
Just an FYI, there is another self serve yard about 1/2 mile from the LKQ yard.  It is called "U-Pull Parts." They use to have an impossible to find, limited web site. Now I can't even find that. Oh, wait, I just found it http://www.aadlenbros.com/

They actually use to be two yards (American/Import) but in the past few months they combined both yard at one $2 admission price.  Not as cheap as LKQ on a sale day, but generally cheaper on regular days. The yard is a lot cleaner too.  Again, sorry it didn't work out for you.  I entered the Primo yard near the cashiers.  It is to the far left (facing the trailers), kind of a hole in the wall.  I'm assuming you tried to go in by the center gate (about half way back).  That is used only for bringing the cars in/out.  I actually tried to go out that gate (it was open for cars coming in/out) after my second trip through produced nothing else to buy. The guy at that gate wouldn't let me out.

 The signage at the place is not well thought out.  I think it is run by corporate people who hire low cost employees of limited capabilities.



Offline 65ShelbyClone

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Re: Power/torque limits of a stock 6.75in rear end?
« Reply #12 on: August 02, 2014, 09:32:53 PM »
'72 Runabout - 2.3T, T5, MegaSquirt-II, 8", 5-lugs, big brakes.
'68 Mustang - Built roller 302, Toploader, 9", etc.