RX-3 W/8.8 Axle Suspension

[fritts]

Trying to decide on a rear suspension route for my 76 RX-3. I do not want to tear up my rear seats on the vehicle as I kids will be taken places in the vehicle. Will be used on the street and AutoX. Car was a leaf spring setup factory and am working on a dual wishbone front suspension. If you have seen an RX-3 you would see just how small the vehicle it is ~2000 lbs from the factory ~91 wheelbase. I would really like to move to a 3 link but the length of the lower Link lengths (22" Max) and only being able to mount a short centered 3rd link are keeping me from doing so. A parallel 4 link would require me to have the upper link centered on the axle centerline and links would have to be less than 22" long. Have a shortened/centered 8.8 Explorer axle for the project. With room around the axle an obvious problem I'm wondering if just keeping the leafs (moving to composites) may be my only option. I guess my question is how much will I be giving up with the leaf spring setup? Also will the upper length issues on the 3 and 4 link setups really the deal breakers I think they are? Any other options I should be looking at?

[iadr]

Trying to decide on a rear suspension route for my 76 RX-3. I do not want to tear up my rear seats on the vehicle as I kids will be taken places in the vehicle. Will be used on the street and AutoX. Car was a leaf spring setup factory and am working on a dual wishbone front suspension. If you have seen an RX-3 you would see just how small the vehicle it is ~2000 lbs from the factory ~91 wheelbase. I would really like to move to a 3 link but the length of the lower Link lengths (22" Max) and only being able to mount a short centered 3rd link are keeping me from doing so. A parallel 4 link would require me to have the upper link centered on the axle centerline and links would have to be less than 22" long. Have a shortened/centered 8.8 Explorer axle for the project. With room around the axle an obvious problem I'm wondering if just keeping the leafs (moving to composites) may be my only option. I guess my question is how much will I be giving up with the leaf spring setup? Also will the upper length issues on the 3 and 4 link setups really the deal breakers I think they are? Any other options I should be looking at?

Wrong axle for the car IMO. Too heavy. Toyota 7.5" (especially this) or Ford 7.5 are better suited. 8.8 only if over 325hp/300ft-lbs.

Lots of ways to modify the rear seat to make it less in the way, but still useable.
Lower bars that hang just above the rear wheel's OD (but not into the tire's) would work.

[fritts]

Goal on this build HP wise is 400 whp, 93 on a 13b-rew single turbo setup. I'm hoping with the lower weight I should be where I want to be acceleration wise. I never have been able to stay with my lower horsepower goals without pushing more. Especially with the ease of obtaining E85. So the 8.8 is right for the setup.

Yeah the lower bars I think I can push lower its the upper links I'm worried about. The upper link on a parallel 4 link would need to be at the CL of axle and would need to be shorter than the lower link which raises the pinion angle change issues. Though the suspension travel will not be alot in this setup. The 3 link upper link I could cut into one side of the center of the seat but still don't believe I will be able to get a lot of length on the link, maybe 14".

[iadr]

Goal on this build HP wise is 400 whp, 93 on a 13b-rew single turbo setup. I'm hoping with the lower weight I should be where I want to be acceleration wise. I never have been able to stay with my lower horsepower goals without pushing more. Especially with the ease of obtaining E85. So the 8.8 is right for the setup.

Yeah the lower bars I think I can push lower its the upper links I'm worried about. The upper link on a parallel 4 link would need to be at the CL of axle and would need to be shorter than the lower link which raises the pinion angle change issues. Though the suspension travel will not be alot in this setup. The 3 link upper link I could cut into one side of the center of the seat but still don't believe I will be able to get a lot of length on the link, maybe 14".

Ok. You mentioned taking kids for a trip so I was thinking more resto-rod aims.

The 3rd link axle mount can be cantilever'd off behind the axle a ways. I believe when I looked at that the geometry was surprisingly "normal".
The GM "crossed 4-bar" typical of the muscle era can be made really low as well. I'm not sure 14" is a problem...

[Supra510]

It looks like if you offset the upper link you'd have room. I did it and I couldn't be happier.

My 3 link thread is here: http://community.ratsun.net/topic/58...gets-a-3-link/