Track tires

[justcruisin]

I will be ordering some tires shortly, I am unsure as to what will work best. I need to run a DOT tire.There are distributors for Hoosier and M/T's in my area. Guys here seem to run Hoosiers in a bias ply, my thoughts are these would be best as they are a  more forgiving tire and I am running my original 8 3/4. I am unsure if I can run my 255/50zr17 tire up front with a bias ply out back or should I use a drag radial. I will be using a 15 x 8 rim for the rear and swapping at the track. Car is 71 R/T Charger with factory HD bias springs. I have a set of 15 x 8 so I could change fronts also.

[c00nhunterjoe]

Mickey thompson et streets or the hoosier equivalent. I think quicktime is the name on the hoosier.

[firefighter3931]

If you're going to swap them out at the track I would use the new 275 radial pro tire from M/T 

http://www.summitracing.com/int/parts/mtt-90000001536/overview/

A buddy of mine runs them on his 10 second GTX and loves them.....they dead hook like a slick and have a stiff sidewall which works well with a heavier street car. You can run these at 18-20 psi so the car is stable on the big end. 


I wish they made them in the larger 295/65 size.....I'd be all over a set of those for mine 



Ron

[justcruisin]

The M/T supplier said they don't carry the radial pro's but can get them in. He also said that the ET street is discontinued and are replaced with the ET street R (R for race), my size in these would be in a bias ply. Would I be safe to run either the Bias ply or the radial on my car - track only.

My car is not set up at all suspension wise, it has the stock R/T springs with the addition of a cut down SS pinion snubber at this stage. My understanding is the suspension needs to be right for radials to work properly where it is less critical with the bias ply. 

[firefighter3931]

I ran the drag radials on my car with SS leaf springs and stiff shocks with the old 446 making 535hp/540tq and never had a problem. I had a 727 with 4200 stall and it worked great ! A stick car does not work well with radials due to the shock load at launch but an auto trans leaves "softer" than a std trans.

The bias ply tires need to be run at reduced pressure and with a small tire the car will become unstable on the top end....not a nice feeling at over 100 mph 

If you have an auto trans and heavy street car a radial tire is the way to go....INMHO 



Ron

[justcruisin]

OK, stable sounds good, cheers for the informed reply Ron.

[ottawamerc]

Interesting thread I'm just about ready to push the order button on those tires too justcruisin I have a similar setup as yours and I'm interested to find out what other mods we should do to improve these "rockets"

Scott

[justcruisin]

Hi Scott, I'm probably not the right person to ask on what works best, I think it is a universal answer though - more HP and less weight.

I have only just got into a bit of fun at the track, I really enjoyed it so I am just doing a few things as I go, firstly upgrades for durability with some trans mods, I have the trans out at present and adding red clutches (5 in the front) and Colene steels, red bands (wider front band) billet rear servo, solid front servo, Teflon seals, 16 roller sprag, TF2 kit and a billet front drum with billet retainer and piston as well as full bush and seal kit.

I am upgrading the 8 3/4 rear with 3.91 gear, billet spacer, billet yoke, new universals and high strength axles. I considered a swap to a strange 60 but my engine is nothing radical and cost is a sizable consideration for me so hopefully the 8 3/4 will hold up with the sticky tires. I ordered Hoosier drag radials in a 275/60r15. I would have ordered the M/T pros but nobody would confirm if they were legal at my track or not.

I am not sure what will work suspension wise, I will see how the stock set up works with the tires and pinion snuber.

This is very much a street car and I don't wish to make it uncomfortable to use so it's all a bit of  compromise.

My best time with my street tires and 3.23's is 12.83 @ 109.8. Good luck with your ride.

[c00nhunterjoe]

I scattered hardened axles in my 8 3/4 and you have similar mph to me. If you are building a rear, do the dana.

https://youtu.be/cH1rhB8FIkU

[justcruisin]

Crap - there goes my budget.

Are you running an auto or stick?

[ottawamerc]

I read that the Dana robs alot of HP too, would a 8 3/4 with hardened axles be ok?

[firefighter3931]

Joe runs a 4 spd and I'm sure he dumps the clutch at 4-5k rpm at the track....very hard on parts. 

With an auto trans the launch is much softer and the shockload on drivetrain parts is significantly reduced. With a 727/mild converter and 500hp I would have no reservations running an 8 3/4 3rd member. 

The 8.75 is pretty tough and can take a lot of abuse. 


Ron

[myk]

4-5K RPM?!

[c00nhunterjoe]

The axles broke on 2800 rpm launches. The tires wont hold the car any higher then that. I just feel that if you are going to invest in hardened, 35 spline axles, a new carrier, bearings, new gears, new sure grip unit (to accomodate the axles) then you have purchased everything new except the diff itself so you might as well buy the dana. I will say my dana sees 6000 rpm launches on bias slicks and isnt breaking axles now.....

[justcruisin]

Agreed, if you intend to spend a good amount of money you might as well go for the big ass Dana. I have done some research on the rear end and if you are going to invest in a complete center section with new axles, bearings that will run you to a minimum of $1700. You can get a complete 60, drum to drum with a worm gear center for $2600.  To upgrade my 8 3/4 as I have listed will set me back around $600, albeit with less strength.

I spoke with a member here (Wookie). He broke upgraded axles also but he does run a stick behind a stroker.  he has fitted up a Dana now.

He gave me the following info. 30 spline axles (stock 8 3/4 spline count) 6200lbs,  33spline 8300lbs (Moser),
35 spline Dana 9500lbs.

As far as I know you can only run 35 spline axles with an 8 3/4 with a spool.

My setup is about what Ron described with around 3000 stall. I think I will stick with the 8 3/4 and keep my fingers crossed and hopefully I wont be posting up any broken axle pics.

[Mike DC]

  
The Dana draws something like two dozen HP and it weighs about 25% more (unsprung).  It's not without downsides.




Are any of you guys running a higher-grade "softer" ring & pinion sets to absorb some of the shockload?  

The factory can get Dana 44's to live behind Vipers and I've been told that's a factor in it.  

Some of those high-end gearsets wear out quickly on the street but I think you can get a happy medium range too.  I'd rather periodically replace the gears on schedule than be breaking everything else in the 3rd member all the time.      

[c00nhunterjoe]

The mild 440 in my belvedere with a 727/10" converter that flashed at 3400 broke hardened 8 3/4 axles on drag radials also.
I did not weigh my dana, but i know it weighs less then my 8 3/4. Granted i used lightweight race parts, but i picked up the completly assembled rear and it weighed less then my 8 3/4 pumpkin. Strange 35 spline axles and spool. As far as street use. Over a year of abuse with no issues and the spool is no problem on the street.

[Ghoste]

If you are making enough power to break an 8 3/4 then you are making enough power that the 24 horse parasitic loss (which seems very high btw, where did those numbers come from?) and the extra weight will be overcome.  And if you are making enough power to break the 8 3/4 but still feel you want to run it so that you can beat those Dana downsides, then you probably deserve to continue replacing broken parts.
Drag racing becomes a game of improving the weakest link in the chain.

[firefighter3931]

Here's something to chew on :

A buddy runs his Plymouth at the track with radial slicks. Raceweight is 3800 lbs. Engine is a 493 with Indy heads making well over 600hp/600tq and he runs a 4200 Dynamic converter in the car with an 8.75 3rd member. It still has the 50 year old stock axles. The only upgraded part(s) is the Detroit locker and 4.30 ring & pinion gear set.

Nothing is bulletproof but as previously stated I would have no problem running an 8.75 in a B-Body with drag radials and a 500hp 440 using an auto trans....foot braking the car.  A trans brake is a different story but I don't think that applies in this case with the OP's car.


Ron

[c00nhunterjoe]

Here's something to chew on :

A buddy runs his Plymouth at the track with radial slicks. Raceweight is 3800 lbs. Engine is a 493 with Indy heads making well over 600hp/600tq and he runs a 4200 Dynamic converter in the car with an 8.75 3rd member. It still has the 50 year old stock axles. The only upgraded part(s) is the Detroit locker and 4.30 ring & pinion gear set.

Nothing is bulletproof but as previously stated I would have no problem running an 8.75 in a B-Body with drag radials and a 500hp 440 using an auto trans....foot braking the car.   A trans brake is a different story but I don't think that applies in this case with the OP's car.


Ron

Now THAT is impressive. My belvedere might have been at the 500 hp mark and i couldnt keep axles under it. 440, 10.4:1, ootb eddy rpms, comp xehl cam, full weight car, 3.91s and 275/60 drag radials. Foot brake car. Stock axles had a beautiful spiral twist before they snapped, hardened axles just broke clean off.

[firefighter3931]

Ya, the car runs excellent.....10.70's at 125mph. This is also a pump gas build that he drives everywhere. 

He knows that he's on barrowed time with the big stroker and that setup so at some point he'll upgrade to the D60 and be done with it.

A 12 second B-body is a far cry from a 10 second street/strip beast so that's why I figured it was worth mentioning. 

From what I've seen....the ring gear is the first to go, then the SG and finally the axles. The 8.75 is a pretty tough rear end. 


Ron

[c00nhunterjoe]

I had the standard Richmond 4.30 gears in mine on a stock clutch style sure grip. She was tight enough that even with the broken axle, i could still limp the car on level ground.... lol. It was a great rear, but i love my dana.

Its also hard to beat that view....

[justcruisin]

Appreciate all the feed back. The car will never be a 10 second screamer, my plan is to upgrade until I can run in the high 11's. I have no intention of going any quicker - at least not with this car. I will be going with the current rear so what would be your recommendations to beef it up. I will be onto it as soon as the trans is back in which wont be too far away as I have all my parts. My plan was axles(DR Diff), ring and pinion(US Strange) billet yoke and high strength front and rear universals. Center is a cone type - I have had it down and it is in good condition with .040" clearance on the cones.

[Mike DC]

The mild 440 in my belvedere with a 727/10" converter that flashed at 3400 broke hardened 8 3/4 axles on drag radials also.
I did not weigh my dana, but i know it weighs less then my 8 3/4. Granted i used lightweight race parts, but i picked up the completly assembled rear and it weighed less then my 8 3/4 pumpkin. Strange 35 spline axles and spool. As far as street use. Over a year of abuse with no issues and the spool is no problem on the street.

Man, I just can't imagine a Dana being anything but heavier.    The Dana has bigger internal parts, a bigger case, and that case is entirely cast-iron rather than half sheetmetal.  

A spool would take a fair amount of weight out of either one.  I'm not sure what else in either of those assemblies could be lightened-up in any big way.  You can get an alloy diff case for the 8.75" but it only saves something like 10 lbs.    


I recall an old magazine article where they put both on a scale (stock) and found the 8.75 was around 200 lbs and the Dana was 250.  In fact the writers commented that the difference was smaller than people generally assume.  

[c00nhunterjoe]

My spool is the lightweight race version, as are my axles. Over the winter when i install caltracs, i will weigh my complete rear, drum to drum.