W72

iTrader: (9)

So fabbing up the trans mount for the LS swap, I'm using an adjustable Spohn TA on a scavenged Spohn 200R4 mount. This has placed the front torque mount about 4 1/4" rearward so I shortened the torque arm.

Now, the TA mount will interfere with the slip yoke unless I cut it about 4" more....will this be an issue? Handling or otherwise?

W72

iTrader: (9)

anyone?

sofakingdom

iTrader: (1)

If the TA mount is not at the same front/rear location as the crossmember bolts (or at least fairly close) it will be trying to twist the x-mem and the "frame" 100% of the time. The farther front/rear it moves, the more extreme the problem gets.

Doesn't sound like a good idea to me, for reasons other than handling.

1BADRZ28

iTrader: (2)

I have my Spohn TA shortened 9 inches from their stock length. I have a separate crossmember for it. The main reason was to get it away from the driveshaft input. But that length has been great, as my 60 fts are fantastic.

W72

iTrader: (9)

Thanks for the replies ...the entire spohn adj. TA was from my TTA with a 200R4,so it was crossmember mounted originally(OEM too), and further back then say my 92' trans am's 700r4 mounted TA location.

IF my mock up is correct, and since the 4L80e's rear mount is 2- 5/16" further back then the 200r4's was, and now I'm having contact issues with slip yoke and the TA's front pivot mount, I need to move it back almost 5" more to allow the front TA mount to pivot fore and aft and allow for the slip yoke to well, slip fore and aft too. I'm going to be shortening it a grand total of about 8".

I'm not by any means knowledgeable about suspension, but it seems to me that the shorter the TA the more prone for it to want to push the rear around in a turn, akin to over steer.
But this will be more of a strip car, not an autocross car with occasional street use too.

So, continue with the shortening? or not?

Night rider327

iTrader: (13)

Look up info on here about the jegster torque arm. A lot of people use them and they are short arms

I have one on mine car in fact. Daily driven for years with it.

It's a very short TQ. arm and works great. Yes it can have some braking and cornering hiccups but nothing major. The short design works great for accel. traction for drag racing.

So if it works well then I can't see why shortening the sphon one wouldn't work

W72

iTrader: (9)

Yes, I see what you mean, that bar is short!

I also looked at the 4th gen TA and they look considerably shorter than the 3rd gens too.

Frankly I don't see any other way around this, the 4L80 takes up quite a bit of real estate in that tunnel so stuffing a full length arm along side of it isn't really an option.

MoJoe

iTrader: (5)

The torque arm is tall to reduce up/down flexing from the pinion rotating up/down. It is very thin (or not triangulated) side to side, so the arm would flex for any left/right axle rotation. Therefore, you don't have to worry about cornering forces transmitted through the TA, just the up/down of acceleration (up) and braking (down).

If I have my facts straight, making the TA shorter will help plant the tires and avoid wheel hop on acceleration. BUT, a shorter arm will make brake hop more likely. Where that changes from too long to perfect to too short needs someone with more experience and number crunching than I have done.

It is the LCAs manage the fore/aft location, which includes preventing axle rotation around the vertical axis.

novaderrik

the torque arm controls the up/down angle of the pinion- a longer arm means it swings thru a wider arc, which means less pinion angle change.
the control arms locate the rear axle fore/aft.
the panhard bar controls the location of the axle side/side.

it is a very well designed rear suspension setup that can do everything right once you get it sorted out since each part is only doing one job.

a shorter torque arm plants the rear end harder on acceleration due to the shorter lever arm, but also unloads the chassis harder on braking due to that same leverage.