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Aftermarket rear sub-frame comparisons

BDKR

BDKR

Section 9
Joined
Nov 16, 2003
Location
Horizons Cave
After having recently finished an install of an earlier generation Kahplenke sub-frame, I was looking around for other things and stumbled across the one for sale at Retro-Turbo. I can't stress how shocked I was at how different it looked. Here are some pics....

Retro Turbo
Volvo-940-740-reinforced-adjustable-trailing-arms-support-arms-drifting-hill-climb-race.jpg


Kahplenke
Subframev4_fullside_1024x1024.jpg


Who is running the top one? Any thoughts in this design?
 
Looks like it ditches the sub frame and two torque rods and makes it just one torque rod. Seems like it might not keep the rear flat when it goes up and down like the stock setup. When the rear goes up and down compared to the car you want the pinion angle to stay the same, not sure this would do that. Looks like the pinion angle and the rear would twist up and down as it goes up and down.

But it might be long enough that it doesn't move that much and works just fine.
 
One is solidly mounted and 1 has rubber bushings. So the Retro will transmit more NVH but keep alignment a bit better. I would go with triangles. You need solid mounting, rethink the whole rear end
 
sbabbs said:
Looks like it ditches the sub frame and two torque rods and makes it just one torque rod.
Click to expand...

Or perhaps you could say it it's an amalgam of the a sub-frame and torque rods?

The Retro Turbo unit does at least provide some adjustment to make sure the pinion angle can be set, but it looks like that entire assembly pivots up and down in the provided bushing. That means it controls movement up and down through a single pivot as opposed to the OE setup, which is multi-link and therefore has a virtual pivot center that I'm guessing is farther forward (while stationary) than what's used by the Retro Turbo assembly.

All that blathering done, I have to summarize and say that the Retro Turbo unit probably gets the job done, but it changes the kinematics of the rear suspension! If it's arrived at something better than what the Volvo engineers concocted, then right on! But I somehow am not sure they are aware of how they've changed things.

Dan said:
One is solidly mounted and 1 has rubber bushings. So the Retro will transmit more NVH but keep alignment a bit better. I would go with triangles. You need solid mounting, rethink the whole rear end
Click to expand...

Based on what I said above, I'm glad I have the Kahplenke unit.
 
The MKM one is a bit of half arsed job. Functions but that is about as far as it goes. A lot of extra stress is being added to the bush at the front. It is probably fine for a drift car but for other uses not likely to be all that good
 
classicswede said:
The MKM one is a bit of half arsed job. Functions but that is about as far as it goes. A lot of extra stress is being added to the bush at the front. It is probably fine for a drift car but for other uses not likely to be all that good
Click to expand...

Which one of the two is MKM? Thanks.



NVH?
 
I've personally never modified any suspension stuff on a 7/900, but I have had 4th gen F-body's, and the top bar looks a lot like the design of a 4th gen F-body. It probably works phenomenal, but as others have stated, it more than likely will transmit more noise into the vehicle. With that said, I would try the top styled bar without thinking twice if the vehicle was for performance use, it looks cheap, strong, and simple.
 
As far as modifying the rear subframe, kerplunky just makes a stronger stock style rear sub frame. Myself, I just weld up the stock ones with more metal and then buy the kerplunky rods or I do have one set of IPD prototypes.


IPDsubframe2.jpg



IPDsubframe7.jpg




IPDsubframe8.jpg


IPDsubframe5.jpg
 
sbabbs said:
As far as modifying the rear subframe, kerplunky just makes a stronger stock style rear sub frame. Myself, I just weld up the stock ones with more metal and then buy the kerplunky rods or I do have one set of IPD prototypes.
Click to expand...

+12 to this, make your own and if you have issues then see about going someplace else for something better

rps20190306_052120_933.jpg


rps20190306_052256_259.jpg
 
Also good to box in and weld up the part that goes into the dogbone like in this pic. That is the part where the stock subframe tends to bend and break. The weakest link.


weldedsub3.jpg
 
You know.... I was going to modify the OE sub-frame myself but the Kerp' unit popped up for sale for a pretty good price. That said, others that have done the install cut through the OE unit so they didn't have to remove the parking brake line. I'd imagine you guys modifying OE sub-frames are removing the parking brake line?

noz-e8tr said:
That (Retro Turbo) is not gonna keep pinion angle consistent when there is suspension travel.
Click to expand...

+1!
 
We'll you can unbolt everything from the stock sub frame while it is on the car and wa-la, the two halves come apart. That way you don't have to unhook the e-brake line from the rear or the front to get it out of the center of the sub frame. Comprendo? IF your cutting up your sub frame to get it off without removing the brake line then your not thinking..


That being said if your welding up your stock sub frame and you want to put the ebrake cable back through the sub frame like stock after welding it up you will have to unhook the ebrake cable to do that. Or just run it on the outside of the sub, but mount it to it so it don't rub through.
 
thelostartof said:
+12 to this, make your own and if you have issues then see about going someplace else for something better

rps20190306_052256_259.jpg
Click to expand...

Old post, but... where are those lower adjustable torque rods from? I like that they still use bushings vs the heim joints. Even though from now on I'll be driving the wagon a lot less & thoseheim joints probably wouldn't be a big deal.
 
jay f. said:
Old post, but... where are those lower adjustable torque rods from? I like that they still use bushings vs the heim joints. Even though from now on I'll be driving the wagon a lot less & thoseheim joints probably wouldn't be a big deal.
Click to expand...

You don't want to use bushings like those. they overconstrain the rear axle and don't allow enough pivoting.

Theres a reason for the huge voids in the factory rubber torque rods beyond comfort...
 
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