rear end decisions

[low&slow]

Originally Posted by bdiamond

I'd invest in a posi or spool for your dogleg 12 bolt. Who knows??? It may take it... A 12 bolt is pretty tough

I was thinking that as well just for something now before I start building the motor or even some kind of stock posi ford rear end, but at the same time, I don't want to build a rear end to have it break when I add more power.

Originally Posted by PGSigns

If you look at the rule book you are getting into the very regulated chassis specs. You are also getting into a very high dollar chassis. The last top sportsman car I put together was a tad over 130K out of the owners pocket and that was a used Don Ness car and a new motor and trans. Just tell you chassis builder what power you have and let him handle the suspension and rear end. Don't be shocked at a 40K bill from him for a roller.
Jimmy

Jimmy, I'm much aware of the price tag to do what I want to do. I'm hoping that maybe a sponsor or 3 can help out with the price. I can't imagine those big cars being built and raced without sponsors.

Originally Posted by Marv D

I don't know PG,, will a 1000 pounds of torque put him below a 8.50 chassis cert? It for sure depends on it hooking and the power getting through the chassis, suspension and all the way to the track. As you well know, a lot of things between this 1000 pounds of flywheel torque and the track can keep the combination WAY slower than anyone might expect.

Still a 8.50 cert is going to be deep into his pocket. A roller 8.50 car in the 2500ish pound weight is still beckoning $15k $30k+ just depending on the quality / age of the build. And buying a used build is about 30¢ on the dollar these days.

I honestly feel your $'s are very VERY realistic!! Low&slow,, prepare for sticker shoc in what the rest of the package is going to cost!

\

I get what you are saying as well. I'm not looking to go any faster than 8's

Originally Posted by PGSigns

Well the under 700 inches and a single or duel turbo making up to 1500 but at least a 1000 is 1300 plus HP. With a 706 making about 1300 hp and a 1000 ft pounds at about 2550 lbs with the driver we went 7.19 at 192 in not so good air. A truck wont go through the air like a grand am but if I had that much power like he wants to build and and could not run 7.80s some one is getting fired. A good chassis design and someone who knows what to do with it will be needed and 25.1 car will be what he has to have.
Jimmy

Jimmy, those are quick times. Since you guys seem to know more about the rules, is it a realistic goal to have and not go any faster than 8's while keeping as much as a stock body as I can without fiberglass?

Also, what's a 25.1 car?

[Super73]

I am working on going 8's.. Right now I have:

A steal front clip but no hood and cut up inner fenders
Stock front suspension but home made cross member
Stock frame from the front to the back of the cab, CM round tube from there back + 4-link
12 point CM cage
Alum Gen 4 motor with power glide
Summit racing seats

With that said, truck weighs 3,200lbs with me in it, full tank of gas and full 15lb N20 bottle.

I am in the middle of swapping out a built 12 bolt for a 9"

[Marv D]

SFI Spec 25.1E
Application: Pro Stock-type tube chassis roll cage; 7.49 seconds and faster; 2,800-pound maximum.

I'm much aware of the price tag to do what I want to do. I'm hoping that maybe a sponsor or 3 can help out with the price. I can't imagine those big cars being built and raced without sponsors.

All I can say is 1 sponsor for every 1000 sportsman racers. Ya gotta know somebody and then have something pretty 'unusual' that will warrant a 'donation' to the cause. I would venture to guess that most of the cars you see slower than 5 seconds are sponsored by the owner (Or owners business)

[Keith Seymore]

Originally Posted by low&slow

I get what you are saying as well. I'm not looking to go any faster than 8's

Originally Posted by Super73

I am working on going 8's..

Very ambitious....

...but it can be done.

This is my engine builder's car. 477 cu in big block, naturally aspirated. The car has gone 8.20's on motor. The only glass is the front bumper and hood. Built by himself in a one car garage in the Detroit suburbs.

At the events I attend (mostly NMCA Fastest Street Car series) this car is on the high end of well running/stock appearing.

By the way, that #1 on the windshield: that's earned. Four time NMCA World Champion in the Nostalgia Muscle Car/American Muscle categories. I runner up'd twice
in my 15 years with the NMCA/NSCA. Guess who beat me? (lol)

[PGSigns]

Well going racing in a truck or a car takes a good plan. First is what class, next how fast do i want to go, then what rules do i need to meet to go that fast. About what will it weigh, how much power do I need to go that fast and how do I want to make that power. The more detailed the plan the better the end result will be with only having to do things once.
Jimmy

[whitedog76]

Look into the 2003 and newer 2500 series GM vans. They have a D60 axle that has 3.5" axle tubes and huge bearings. With some custom shafts, it would be a stout setup.

[Marv D]

Going low 8's on that tire is quite an accomplishment!!! What is it a 8.5" slick?

[Keith Seymore]

Originally Posted by Marv D

Going low 8's on that tire is quite an accomplishment!!! What is it a 8.5" slick?

26x9 M/T slick, or he sometimes runs a drag radial.

I tease him that my front tires are bigger than that.

He actually got thrown out of a Milan All Motor meet because his tires were too small....at least that was the excuse they used.

K

[Tom Vogel]

Originally Posted by

he actually got thrown out of a milan all motor meet because his tires were [i

too small[/i]....at least that was the excuse they used.

k

what???

[Keith Seymore]

Originally Posted by Tom Vogel

what???

I'm not kidding. There were a lot of words over that one.

It's a beautiful car which was built to the letter of the rules. I guess some folks were pretty desparate to find something wrong (after getting themselves embarrassed by its performance).

K

[Fitz]

Originally Posted by low&slow

The truck will be 95% strip with about 5% street. I'm pretty sure I can have my buddy do all the welding on it and I can do the rest. Depending on rates of local quotes, I guess I'll just have to compare prices compared to buying one already made to meet my needs



Right now the motor has about 650 foot pounds of torque and 525 hp. By the time I actually dish out the money on a rear end, I'm hoping to be close to if not more than 1,000 foot pounds of torque and close to if not more than 900 hp. My goal is to get up to around 1,500 foot pounds of torque and more than 1,000 hp without nitrous in order to stop building up the motor. Size of rear tire I'm planning on running is 33.5" x 17"-16 goodyear eagle slick or a 33.0'' x 22.50'' - 15'' with a 17'' tread width Hoosier quick time d.o.t. drag tire.

Your 12 bolt will take 650 Ft-Lbs without too much stress but it will never stand up to 1500. You will need a bullet-proof professionally built diff for that.

[low&slow]

Originally Posted by Fitz

Your 12 bolt will take 650 Ft-Lbs without too much stress but it will never stand up to 1500. You will need a bullet-proof professionally built diff for that.

Alright. That's good to know just till the end of the summer. As for the 12 bolt, should I build it up a bit with a posi in it to handle the nos I may run or find something else just for now? Either way, I need to get a posi.

[hotrod 80]

Originally Posted by whitedog76

Look into the 2003 and newer 2500 series GM vans. They have a D60 axle that has 3.5" axle tubes and huge bearings. With some custom shafts, it would be a stout setup.

Thank you sir , this is great information , learned something today .

Originally Posted by Marv D

Going low 8's on that tire is quite an accomplishment!!! What is it a 8.5" slick?

8's on a 26 x 9 is getting it done.

Originally Posted by low&slow

Alright. That's good to know just till the end of the summer. As for the 12 bolt, should I build it up a bit with a posi in it to handle the nos I may run or find something else just for now? Either way, I need to get a posi.

What is your fastest pass so far without a posi unit ? were you planning on spraying it with an open diff ?

[low&slow]

Originally Posted by hotrod 80

Thank you sir , this is great information , learned something today.

I agree. Great info here.

[/QUOTE]What is your fastest pass so far without a posi unit ? were you planning on spraying it with an open diff ?[/QUOTE]

R/T: .078
60': 1.972
1/8: 8.443
MPH: 83.02
1/4: 13.053
MPH: 100.56

I'm not exactly sure what my rear end is. I can do a burnout and the passenger tire spins, but I can do another burnout in a different location and the driver side tire spins. I know it's not a posi though. I've had a posi.

[familyfast64]

Tech keeps the poor guy slow unless he keeps clear of the track... Ridiculous prices! I could build a nice house and prolly do it in less time.... What's the deal there? Gut check! That's why I bought a welder. And let me tell ya, it's not hard. Altho im no pro, cause I lack experience, learning is easy. Forget paying

[GMR-PERFORMANCE]

9 inch from moser is rated 1250 with 35 spline axles wavetrac no less.. Spool may rise the limit.. I bought a complete unit and love it. Works great.. no I live in world of 1/8 mile tracks and 5+ gear ratio's

[low&slow]

Originally Posted by GMR-PERFORMANCE

9 inch from moser is rated 1250 with 35 spline axles wavetrac no less.. Spool may rise the limit.. I bought a complete unit and love it. Works great.. no I live in world of 1/8 mile tracks and 5+ gear ratio's

That's not to bad. Mind sharing a price on your axle and all?

I just got a 70 c20 yesterday. Now I know it's 8 lug and I can't imagine it being to hard to switch to a 6 lug, but are the 3/4 ton axles stronger than a 1/2 ton? I'm hoping there's a way I can use it if it's a posi.

[GMR-PERFORMANCE]

Originally Posted by low&slow

That's not to bad. Mind sharing a price on your axle and all?

I just got a 70 c20 yesterday. Now I know it's 8 lug and I can't imagine it being to hard to switch to a 6 lug, but are the 3/4 ton axles stronger than a 1/2 ton? I'm hoping there's a way I can use it if it's a posi.

I am a dealer for these parts so no I cannot give you a cost other than retail. which you can look up on moser site.
I am running 6 lug rear wheels and 5 up front. Not like I can rotate the tires anyways . But you can get just about any bolt pattern and size you want. I am running 6 big studs vs 5 on the rear. In the end 5 is more than strong enough just something i wanted due to a issue with another race car I had.


GO to Moser and spec out what you want. Something like I have is not what most need. 33 spline pressed bearing vs timken etc it all adds up. When you go to 35 spline some things are a must in the ordering process like a nodular housing. certian type of axles and so on.

Direct fit no mods needed on my end what so ever..

On the axles if you are asking me about 12 bolt stuff I dont bother. My opinion is you are only waiting to break it and when you do the cost will be enough that a 9 inch would have already been paid for. I run my stuff double duty.. and its get the bottle on the street as well the track.

If that a track truck spool it and forget about the posi unit. But the stock axles are not long for this worl with heavy power and adding c clip ends aluminum rear support cover .. I went through that thats why I have a 9 inch now.

[hotrod 80]

Originally Posted by low&slow

I agree. Great info here.

What is your fastest pass so far without a posi unit ? were you planning on spraying it with an open diff ?[/QUOTE]

R/T: .078
60': 1.972
1/8: 8.443
MPH: 83.02
1/4: 13.053
MPH: 100.56

I'm not exactly sure what my rear end is. I can do a burnout and the passenger tire spins, but I can do another burnout in a different location and the driver side tire spins. I know it's not a posi though. I've had a posi.[/QUOTE]

Even with a Posi unit the axles typically break at the splines . On a factory 12 bolt that allows the axle and brake drum to be free . A posi and C-clip eleminators are the minimum i would suggest for your stock axle be it 12 bolt 8.875 or 10 bolt 8.5 .

[GMR-PERFORMANCE]

Hotrod posted up what I am saying..

Buy the c clip units, better axles a spool rear diff support new ring and pinion .. add that all up and you got a 9 inch he he

[GMR-PERFORMANCE]

I have been seeing some good deals on used / new 12 bolt parts on some local FB pages here in this area.

[aotte1]

Another source for a rear axle housing or rear end is DTS Drive Train Specialists in MI or WI. They make really strong rear end housings. DTS makes certain Mark Williams housings, they did a few years ago, not sure if they still do.

Like Keith S. I used upgraded stock 10 bolt into the 10s for a decade, now have DTS 12 bolt with chrome molly tubes, etc. and MWs insides, dual calipers each side with stainless steel single rotor [SS is lighter]. Dual calipers are for launching, not stopping. I am down on HP/torque to Keith only about 600/600, getting into the mid 1.30 60 foots.
Launch and stall in the 5s, think close to 2 gs at launch. And thats on radial 9 inch slicks light weight with over 25 PSI. Picture is with 10 bolt still in car.

[FB85C10]

I used my GM 10 bolt from my 85 truck and put new everything: I got 31 spline moser axles, auburn differential, 3:73 richmond gears, axle tubes welded and moser rear cover verus building a 9" rear in my truck less expensive for me atleast!!

[GMR-PERFORMANCE]

It is about the intended use of the vehicle.. A nice 9 inch with a price tag of 3200 for a complete unit. like mine is going to handle more abuse that a built 12 bolt, and when the 12 bolt breaks ( pinion area is week ) you are going to be into the build for more than you would have up front with a 9 inch. 10 bolt i not a tough unit by any means and the do break. Now this is the performance section so take that for what it is. We are not taking it easy on the stuff in this section. high stall sticky tires NOS , turbos blowers etc. That type of use will show the weak link in a hurry. For a guy wanting a double duty the 9 inch lends itself there as its easy to swap entire center sections. So race season is a 4.13 gear and then you want a road trip easy swap the section out to a low dollar unit with 355 gears and cruise down the hwy. I opted for a 3.73 with .75 4th gear OD. I may look into a set of 4.10 gears.. Current is 70 MPH at 2450. A very happy middle of the road. Its all in how you look at it. Myself would not waste the money on the 12 bolt. As I have broke many and tough as they are they are not as strong as a 35 spline item that will handle 1000 HP + and never skip a beat. FB what do you have invested in that unit I would think at least 1500 closer to 1750 using retail plus the cost of the unit to start with as the early trucks had 8.2 ring and pinion . Look at what you will do with it then add 25% of the abuse factor and see where it lands