Author Topic: Open spool or posi-traction rear ends??  (Read 18198 times)

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Offline Richard 2

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Re: Open spool or posi-traction rear ends??
« Reply #15 on: March 20, 2014, 10:39:44 PM »
Dallasv, Are you running N/A, Blower, or Turbo?
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Offline SPARKY

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Re: Open spool or posi-traction rear ends??
« Reply #16 on: March 21, 2014, 02:14:53 AM »
I have run all 3

 I will stay with the Torsen ---gives you BETTER than the best of 2 worlds--the  Torsen is a spool when over powered, open with no wheel spin, and more power to the wheel with the best traction  the two wheels stay the same wheel speed.  The only time with the Torsen lets one wheel turns faster than the other is going around a corner.
On top of that, it is over 4% more efficient that the 9" which = 4% more thrust with the 7.5 over the 9"---How much faster will you go with 4% more power?
« Last Edit: March 21, 2014, 07:47:02 PM by SPARKY »
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Offline Skip Pipes

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Re: Open spool or posi-traction rear ends??
« Reply #17 on: March 21, 2014, 03:27:24 AM »
I’m with Sparky.
Based on his recommendations, here’s my 7.5” with a Torsen.
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Offline DallasV

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Re: Open spool or posi-traction rear ends??
« Reply #18 on: March 21, 2014, 09:50:07 AM »
Dallasv, Are you running N/A, Blower, or Turbo?
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Have run N/A and Blown.
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Offline Sumner

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Re: Open spool or posi-traction rear ends??
« Reply #19 on: March 21, 2014, 12:54:21 PM »
I’m with Sparky.
Based on his recommendations, here’s my 7.5” with a Torsen.



Sorry and not to hijack the thread but Skip did you take Ford 9 inch axle tubes and slide them on the 7 1/2 axle tubes?   That is what I'm thinking of doing since the GM has a 2 5/8 OD and the Ford are 2 5/8 ID.

Thanks and nice work,

Sum

Offline Rex Schimmer

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Re: Open spool or posi-traction rear ends??
« Reply #20 on: March 21, 2014, 02:55:52 PM »
Just to add an additional thought to this thread, you also need to be aware of your cars corner weights. I know that many racers do run there cars over scales and know what their wheel weights are but my guess is the majority don't. If you have a car that has a short wheel base, stiff frame, especially in torsion, a wide rear axle (I think I am describing a roadster!) then cross weight can have a big affect on if your car will go straight regardless of the open or locked diff. The weight that the rear wheels carry is pretty constant, except during heavy acceleration, so any weight that is taken off of one rear wheel by either static cross jacking or dynamic cross jacking will be transferred to the other wheel, which of course make that wheel drive more and because the rear end is wide it will generate a greater moment about the cars CG and try to drive it in one direction. High spring rates or solid mounting of the axle make it even more sensitive to dynamic jacking. If you happen to be thinking about building a car with completely solid suspension both ends you had better make at least one end adjustable or you could build in cross weight that you cannot change.

Just an additional thought.

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Offline Stan Back

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Re: Open spool or posi-traction rear ends??
« Reply #21 on: March 21, 2014, 03:05:39 PM »
. . . only tried it for one run.  Made a believer out of me just past the 2 at about 200.

By the way, I'd shut off the gas and lights, had the clutch in.  Don't remember doing any of that while watching the world spin by.  Came to a stop, turned 'em back on, and started to drive over to the return road when the emergency crew caught up with me.  Guess they wanted to talk to me.
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Offline jimmy six

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Re: Open spool or posi-traction rear ends??
« Reply #22 on: March 21, 2014, 07:05:33 PM »
My roadster came with a spool in the quick change and after a year I took it out. It went where it wanted to go and not where I wanted too. Eventually went to a Pontiac rear. I've been 216 on 75% nitro open with no problems.

I remember Roy Fjastad's Pontiac continuing to spin one year, we were talking at his shop offseason and he mentioned it. He had a spool and I suggested he take it out. He did and the car never spun again. Some times it's just the car and how it's set up. A car accelerating to 200+ in 5 miles is a lot different than one accelerating to 250-275 in 5 miles...good luck.
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Re: Open spool or posi-traction rear ends??
« Reply #23 on: March 22, 2014, 06:01:55 AM »
Slightly off topic question.....What would be the recommendation for front wheel drive?

As some of you know, I am setting up my Dodge Rampage for BMMP and it will be an automatic FWD.

Brian Gillespie's Hondata CRX and John Romero's AEM Civic are FWD and I think I remember that both use a Torsen type LSD.

A Torsen type LSD is available for the automatic transmission as are high HP axles. I'm planning/hoping to have a 51/49 front to rear it will be corner weighed.

I will be getting the transmission to my builder within the next few weeks so I would like some opinions for my FWD setup.

Gregg

Offline Dr Goggles

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Re: Open spool or posi-traction rear ends??
« Reply #24 on: March 22, 2014, 06:08:43 AM »
Sorry and not to hijack the thread but Skip did you take Ford 9 inch axle tubes and slide them on the 7 1/2 axle tubes?   That is what I'm thinking of doing since the GM has a 2 5/8 OD and the Ford are 2 5/8 ID.

Holy  :roll: that's a good get, we had to get some hollow bar turned up to hook our 8.8 axle tubes to the ten bolt pumpkin. Just sliding the axles tubes over is waaaaay easier.... :cheers:
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Offline wheelrdealer

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Re: Open spool or posi-traction rear ends??
« Reply #25 on: March 22, 2014, 09:12:04 AM »
Sumner:

Second hijacking!

What a great idea. I have been thinking about this for a year and never thought of the two tubes nesting. I have a "D" motor Camaro so every 4% helps. I currently have a 9" and 4 built center sections. So far I have only used the 3:70 for the concrete mile and a 3:50 for Bonneville. Can you give me more details on how you figured you would do this? I.e. how much of the 7.5 tubes would you slide into the 9" tubes? Would you weld the inside edge to the existing 7.5 tubes or to the pumpkin? What are your thoughts on axles the 7.5 axles with bearings, seals and races that fit the Ford end tubes?

So it is not a total hijack. I ran an open rear, 9" with 3:50, 28" tires and was very happy with the handling of the car. I only make 492 hp at the flywheel and less hp at 4,900 ft. so we have not had a traction problem.

Thanks,

BR
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Offline SPARKY

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Re: Open spool or posi-traction rear ends??
« Reply #26 on: March 22, 2014, 11:27:46 AM »
Sid has already pointed out there are Ford 28 splines that will go into the GM 28 spline Torsen carriers  :-D 
Miss LIBERTY,  changing T.K.I.  to noise, dust, rust, BLUE HATS & hopefully not scrap!!

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We are going to explore the racing N words NITROUS & NITRO!

Offline Sumner

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Re: Open spool or posi-traction rear ends??
« Reply #27 on: March 22, 2014, 12:12:58 PM »
Sumner:

Second hijacking!

What a great idea. I have been thinking about this for a year and never thought of the two tubes nesting. I have a "D" motor Camaro so every 4% helps. I currently have a 9" and 4 built center sections. So far I have only used the 3:70 for the concrete mile and a 3:50 for Bonneville. Can you give me more details on how you figured you would do this? I.e. how much of the 7.5 tubes would you slide into the 9" tubes? Would you weld the inside edge to the existing 7.5 tubes or to the pumpkin? What are your thoughts on axles the 7.5 axles with bearings, seals and races that fit the Ford end tubes?

So it is not a total hijack. I ran an open rear, 9" with 3:50, 28" tires and was very happy with the handling of the car. I only make 492 hp at the flywheel and less hp at 4,900 ft. so we have not had a traction problem.

Thanks,

BR

So as to not divert this thread from its original intent I've started a new one in the Technical Section about the possibility of using the Ford tubes on the GM housing here...

http://www.landracing.com/forum/index.php?action=dlattach;topic=13730.0;attach=45690;image

Sum

Offline kiwi belly tank

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Re: Open spool or posi-traction rear ends??
« Reply #28 on: March 22, 2014, 01:22:09 PM »
Slightly off topic question.....What would be the recommendation for front wheel drive?

As some of you know, I am setting up my Dodge Rampage for BMMP and it will be an automatic FWD.

Brian Gillespie's Hondata CRX and John Romero's AEM Civic are FWD and I think I remember that both use a Torsen type LSD.

A Torsen type LSD is available for the automatic transmission as are high HP axles. I'm planning/hoping to have a 51/49 front to rear it will be corner weighed.

I will be getting the transmission to my builder within the next few weeks so I would like some opinions for my FWD setup.

Stick with the Torsen. A FWD with a spool will want to go where it's pointed. I've tried it on dirt tracks & it was a bitch, I can't imagine trying to 'herd' one at speed on the salt. :-o :-o
I have Torsen's on both ends of the liner.
  Sid.

Gregg

Offline Richard Thomason

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Re: Open spool or posi-traction rear ends??
« Reply #29 on: March 22, 2014, 01:38:16 PM »
On the Danny Boy which was front wheel drive, we ran a spool. When the geometry was correct, it always went straight as a string and we could put the car anyplace we wanted. More than a dozen runs over 340.