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OJR
OJR New Reader
4/9/18 7:35 p.m.

The spur gears are extra drag. It has a lot more ($s) bearings to add drag than a normal R & P but I'm sure not 50hp.

I can turn it by the driveshaft with one hand!

I didn't design, plan or build this. I'm just stubborn enough to keep it as it was. I have a copy of a grid sheet from 1982 that could have been it's last race before I got it in kit form in 1998.

Long ago the " something competition" or "Competition Something" shop (in CT) that built Paul Newmans first 510 built a different make sedan with this setup. Then Al bought that car and wrecked it in his first race. Then he built this car using many of the unusual for an SCCA sedan parts from the wreck.

The photo shows the Jacobs Ladder and the holes for adjustments.

 

 

 

freetors
freetors Reader
4/10/18 7:39 a.m.

Looks like the theory to that is basically the same as a scrunched up panhard bar with a lot more rod ends!

OJR
OJR New Reader
4/10/18 9:33 a.m.
freetors said:

Looks like the theory to that is basically the same as a scrunched up panhard bar with a lot more rod ends!

 Yes it's like a panhard bar but much longer. You add the lengths of all the bits. This gives much less side movement than the arc of a panhard bar. The Jacobs ladder has 5 points with 3 holes each. The roll center can be changed from adjustments here. I'd like to know what does what before I change it more than I have.

 

OJR
OJR New Reader
4/10/18 1:35 p.m.

The rod ends....AARRRGGG!

I have left hand taps I've used on customer and other parts/projects.

All of the rod ends on this car  are right hand thread.

 

Knurled.
Knurled. MegaDork
4/10/18 7:43 p.m.
freetors said:

Looks like the theory to that is basically the same as a scrunched up panhard bar with a lot more rod ends!

 

Or a Watts link that has been folded in on itself.

Knurled.
Knurled. MegaDork
4/10/18 7:54 p.m.
freetors said:

So what are some donor cars with really light rear axles? I've toyed around with the idea of putting on a four link system on the MGB but I also wanted to get rid of rear unsprung weight. That factory rear axle is seriously heavy for a car with less than 100hp.

 

The Ford 7.5 is reasonably strong and light enough.  The reason I like it for the RX-3 is the RX-3 has a track width of only 50".  If you get an early Ranger axle, if you cut the (left?) side shorter and use two (right?) side axles, you end up with something in the 52" width range, with junkyardable/Dorman-able parts availability.

 

Alternatively, I also like the idea of grabbing a Trailblazer rearend and having axles made with 9" bearing ends.  Upside:  Magnesium centersection of dubious strength (but good enough for 100hp, eh?)  Downside:  You gotta get custom axles made no matter what, which means money.  Dutchman's pretty cheap at $400-ish for a pair depending on options.  But there's an upside to that:  You can have them made to YOUR specs.  So whatever bolt pattern or brake width dimensions you want.

 

For what it's worth, the Ivan Stewart era Toyota stadium trucks used magnesium case Dana 60 rearends.  4-link mounts on the case were bolted to it rather than welded.  Neat stuff.

Knurled.
Knurled. MegaDork
4/10/18 7:58 p.m.
OJR said:
freetors said:

Looks like the theory to that is basically the same as a scrunched up panhard bar with a lot more rod ends!

 Yes it's like a panhard bar but much longer. You add the lengths of all the bits. This gives much less side movement than the arc of a panhard bar. The Jacobs ladder has 5 points with 3 holes each. The roll center can be changed from adjustments here. I'd like to know what does what before I change it more than I have.

 

It looks to me like what you are doing by adjusting the locating points on the center piece is akin to adjusting instant center on a 4 link, except laterally.

 

The trig nerd part of me is foaming at the mouth regarding the possibilities!

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