Too much Torque?

[Broadkill1]

I am running a 521 in my everrett morrison with 650hp and 670 lbs of torque. This is for the street only and not for the strip or track. I have a 8.8 stock rear with 3:73 gear ratio and a tremec 600 trans. Should I give a 9" rear some thought or is this not necessary?

[CobraEd]

The 8.8 is an incredibly strong rear, but the 9 is about the strongest there is. Good chance the 8.8 is fine.


However, with that engine, I would lose the 3.73 ratio and go with a 3:23 or 3:08 or you will never hook up unless you run wrinkle wall slicks. I have to believe that first and second are totaly useless with those gears.


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[Gaz64]

Originally Posted by CobraEd

The 8.8 is an incredibly strong rear, but the 9 is about the strongest there is. Good chance the 8.8 is fine.


However, with that engine, I would lose the 3.73 ratio and go with a 3:23 or 3:08 or you will never hook up unless you run wrinkle wall slicks. I have to believe that first and second are totaly useless with those gears.


.

Yes, fully agree.

With that much grunt, taller gears will be a better package.

If second gear is "undriveable" with 3.73s or lower, then the engine can't be enjoyed until 3rd gear.

[jhv48]

With that much torque on tap, you don't need any gears except fourth.

Leave it in fourth and just spin the tires to get going. Saves on clutches too. Although you will tend to eat a few sets of rear tires every year.

You'll never be able to hook up the tires at anything more than 1/4 throttle in the first three gears anyway.

[STL Mark]

No strip or track - leave it alone.
You'll never apply the much power to the pavement anyhow.
Enjoy it. Save the money for gas.

[Zoom This]

Tires will just spin, relieving the drivetrain shock of any amount of torque. Wrinkle wall slicks will break a half-shaft faster than anything. The 8.8 rear is a very stout rear end for street use with big torque motors. Just keep an eye on axel housing mounting points which can crack or just plain break under abuse. Like others have said, ditch the 3.73's for a 3.27 or higher ratio. Have fun!

[bobcowan]

I agree with above. The 8.8 won't be the weak link, you'll break traction long before you break the diff.

If you're using the stock typ LSD, you'll wear the clutch packs out pretty soon. Keep an ear out for the One Wheel Peel. When that starts happening, replace the the diff with a worm gear like the T2 or TruTrak.

I would disagree a little with the gear selection, though. With that much torque, you really don't need additional torque multiplication of a low gear. But, in a street car, a low (granny) gear is often quite handy in parking lots, heavy traffic, loading on a trailer, etc. It's nice at a cruise in to be able to creep along in first without slipping the clutch. If you're worried about too low of a gear, you can always start out in 2nd. As long as 4th and 5th match your driving style and engine performance, leave it alone.

[RICK LAKE]

Broadkill1 What tires are you running? What is the first gear ratio on the trans?
As far as an 8.8 rearend, there are some things you can do to make it stronger.
Complete welding of the tubes to the center section if not done.
Better axles (higher spline count) if not already done.
Rear differential support cover to stop walking of caps in rear
Reinforce all mounting brackets on rear tubes.
Drop the ratio to a 3.25 IF the trans ratio in in the 2.80's for 1st gear.
If too much torque is the problem, better tires or advance the camshaft to kill some of the bottom end grunt.
There are a couple of 8.8 rear build ups in HotRod, Car Craft, Hot rodding, 5.0 mustangs and Fast fords. They build for 700hp motors and 1/4 mile runs. How the bearings, perload, backlash, and setup will be how well the rearend holds up and how long.
As for the 9" rearend, some are stronger and some are alot weaker that your 8.8. Moser and Currie are to of the better known places to buy from. Alot has to do with the material thickness and qualitity of the steel. How the tubes are welded to the housing and if done straight or not. The nice thing about a 9" is you can change rearend gears in about 1 hour.
Last thought if money is no problem, go with a quick change rear like Franklin. You will have the best of all worlds. Rick L.

[Gaz64]

Rick,

Don't you mean "retard the cam to reduce low end torque"?

[blykins]

Retarding the cam timing should kill a little bit of the low-end. However, it's not going to kill it enough so that it's no longer a problem. 670lb-ft is a butt load, and making it 650 won't make the problems go away.

The 8.8 is a tough rearend as long as you got good axles/half-shafts. A lot of the 5.0 guys run into the 9's with 8.8's and C-clip eliminators. With any kind of street tire or drag radial, you're going to lose traction before you hurt anything anyway.

I'd leave it alone...

[Excaliber]

Heck I'm running slicks and still can't hook up enough to break anything, tire spin is really bothering me. I guess I'll have to move up to some wrinkle walls to get anything done.

Classic 3:31 rear gear in a Jag IRS with a TKO 600. First gear is TO low for me, 2nd is still worthless. Wow, I can't imagine a 3:73. Maybe you should consider a THIRD gear start??

...oop's, there went the clutch, but the ET was fabulous for that run!

[CobraEd]

A special relay setup that cuts off voltage to two cylinders until you are above 3,500 rpm.


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[Jerry Clayton]

All the things mentioned are pretty valid---

One really big reason to consider would be the pinion angle at ride height ---the pinion line is quite a bit lower than the 8.8

with such a short driveshaft this angle differance grows rapidly

For those of you who think a spinning tire loses the torque somewhere have never seen parts that have broken as a spinning wheel hooks up---the sudden application of torque to the non rotating parts is multiplied by the enertia of the spinning wheels mass plus the engines torque--

Thats the reason that the SPF cars break the left half shaFT--when the right side gets traction and stops spinning

[COBRANIP]

Rick Lake:
"Last thought if money is no problem, go with a quick change rear like Franklin. You will have the best of all worlds. Rick L."

Since the Franklin has an extra set of gears the power must go thru, any idea how much "extra" power that consumes compared to the 9"? Or, in general, how much less efficient are the quick change rear ends?

Thanks,
John

[Jerry Clayton]

the q/c rears have an even lower drine shaft line and the extra gears and housing on the back complicate the fuel tank area--not only for the gear case room but clearance to change the Q/C gearsets.With the pinion / ring gear is at 0 * offset compared to the 9er, you probably won't lose as much power thru the Q/C gears as one might think. On the
9er you do have choice of some gear tooth counts that would reduce drag

[STL Mark]

It's a street car - no track or strip intentions as he stated. All great points, but if he just stays with street tires and his current set-up, he'll break traction when he wants some fun and won't break any parts. And with gas heading towards 4 bucks a gallon he could keep his pennies for cruising. That beast will be drinking gas like crazy anyway.

[RICK LAKE]

Gaz64 Yes you are right. The other question is we don't know if the camshaft was just dropped in or was setup to camshaft manufacture specs.
The other things are this
this motor is a 521 I think he said, how big is this camshaft?? That's a nice size 460 over built. Retarding the camshaft will kill alot more than 20 ft of torque. more in the range of 40-60ft. It may only kill about 20 HP down low. A small camshaft in a 482 motor with .600" total lift kill 35 ft of tork in the bottom end with a 4 degree change. Remember that these camshafts are designed for smaller motors. 70-90 more cubes is alot of extra room to fill. Kill the timing also will do the same thing. Rick L.

[RICK LAKE]

COBRANIP John A guy here on the forum did it with his cobra in an ERA car. I think his name on the forum was N2000JR or something like this. Have not seen him on here in a couple of years. I talked to him. Alot of work to get this to work. I have a file on it but this was on the old computor that crashed. Have no way to retreive it. Need an old 850. The Gas tank was notched out to clear the rear cover. It was not a quick change like dirt track cars and took a couple of hours. Normal would be in the 10-20 minute range. The guts are 9" parts with a 3.70 ratio. You can go from the low 2.00 to 7.00 something with just a swap of 2 gears and fluid. A differential cooler and pump can be added. You can get an internal or external pump to move the fluid. I looked at this setup myself. It's quicker to change rearend carrier assemblies in an ERA then to swap gears in one because of room. Rick L.

[Broadkill1]

Guys, thanks for your replies. The engine was built by a builder in Colorado Springs and has only 400 miles at this point. I would rather not touch the engine. I was wondering if maybe a higher gear ratio would allow more stick or if a strong 9" rear would be necessary if I could acheive more stick to the road. I like the NTO5 Nitto tires that I am running but with this much engine I know that I am asking alot from the tires.

[BBfangs]

Broadkill,

I have similiar numbers, 630hp and 675 torque. I have a Dana rear with 3.08 gears running a Richmond 5 speed. I used to run Goodyears but needed to replace and went with Vredesteins. They are pretty good with grip but with that much tq at 3800 rpm it breaks lose anyway. I haven't run it at the track and if I did would use slicks. Off the top of my head I don't remember the ratio of first gear so I can't comment what that is. I worked the bugs out last summer so I am looking forward to having fun come the season. Good luck with it.