79-85 E body suspension question(s)

[TJ Hopland]

Just picked up one of the cars I have always sort of wanted to own.  1980 Eldo diesel.   I have owned several 4100 cars and had no issues so I figured I would have a try at the only engine people hated more  

I have never really spent much time in this gen E body car before so I am not sure what is normal or not.  Everything feels pretty decent except when going over bumps.  My impression is its 'bump steer' in the back.  My stock 66 mustang does the same thing except in the front.  It feels like as the suspension is moving the rear wheels are steering.   I see its an independent rear setup.  I looked under it in a parking lot and it looks like the sway bar is in tact.  Air shocks seem to be working and they are not the worst shocks I have ever felt although I am sure they could be doing a better job of damping.   

I assume this was / is not normal for these cars.   Is there some area I should be looking for wear?   Odometer says 57K and based on the interior I would say that is actual so I would not expect metal parts to be shot but perhaps some dry rot on some rubber?

[Otto Skorzeny]

Don't know about the shocks but you can convert that car to burn restaurant cooking oil for about $300 and drive for free. Seriously.

[Dave Shepherd]

Here I go again. LOL, When I was a field troubleshooter for Cadillac, we found bump steer common on many of the early fwd GM cars, most of the time it was caused by and idler replacement where the center drag link was not parallel to the ground as the original installation height of the idler bracket was lost.  This assumes all suspension and steering components frt and back are not worn/loose.

[TJ Hopland]

Got a chance to have a closer look at things.   All seems well with a quick check to both front and back suspension.  I did not do a real in depth look but nothing appears to be falling off.   I did find that even though the compressor runs and the light seems to cycle on and off on the dash that the rear does not actually lift.  Found a leak in one of the lines so tomorrow I will see if that leak is the only issue or if new shocks are needed.  They do appear to be a parts store warehouse item.  I imagine getting the car level will help a lot.   Anyone know what the ride height should be?    Also found the tire pressures to be high and uneven.  Got em all where they should be so now its time for a test drive to see if that helped. 

[TJ Hopland]

Also I assume the final drive is just like any other 'rear end' and that the lube should be level with the plug when the car is level?

[Dave Shepherd]

Correct.

[bcroe]

I have a 79 Eldo, low miles.  A bit of "spirited" driving loosened up all the rubber bushings.  Then it handled like a boat, rolling & drifting all over.  I put in really stiff torsion bars, springs, and sway bars.  Bigger tires, all new front bushings, and fender braces above & below the engine.  New steering rag joint.  The last thing that really made it right, was KYB gas shocks in front.  At this point you & I probably need to finish the rear suspension overhaul too.  You can get KYBs for the rear as well, but no air leveling.  Then air bags or different springs would be needed to get the rear up. 

Its hard to see very far back out the rear, because the roof cuts off the view.  I raised the rear a bit, and mounted the mirror somewhat lower, to see under the roof line.  Bruce Roe CLC # 14630 

[TJ Hopland]

Got a couple of splice fittings and got the air line working and as I suspected the shocks themselves both leak so I will have to order some new ones.   After getting on level ground for a look the back is way low so I suspect that getting it back where it should be will help as well as getting some damping in there.

[bcroe]

Also I assume the final drive is just like any other 'rear end' and that the lube should be level with the plug when the car is level?"

I owned 2 79 Toros, and the 2.41:1 final drive failed on both of them before 200,000 miles.  Teeth broke off & jamed.  Before the second failure, I heard they built some bad gears then, so I already had a backup final drive ready.  Put it in overnight.  I think the diesel gets the 2.41 ratio also.  My third 79 E car has a final drive from a 77, so I'm not expecting any failures. 

That THM325 is a decent trans, but you might notice some sloppy shifting.  Mine was caused by a broken spring inside the big cap by the left exhaust pipe, it was broken on every such trans I ever took apart.  A mild shift kit I bought replaced the spring and it worked great thereafter.  Bruce Roe

[TJ Hopland]

I was just asking about the final drive because while I was under there I pulled the plug and oil came out.  It was fairly level at the time so I dont exactally know how it got over filled.  Oil was dirty but seemed like 80-90.  Not trans fluid or water.  Next time its up I may see how much I can suck out and put some fresh in there to the right level.   I still dont know how many miles are on this car.  I noticed today that the non original keys are fairly worn which I would not expect for 57K.

What is this spring you speak of?  I have not looked that close at the trans.  It for the most part seems to shift fine, only the kickdown is a bit wacky but I suspect that my be an adjustment in the throttle linkage and kickdown cable. 

[bcroe]

There is a big round cap on the left side, held by a snap ring.  I had to remove the exhaust pipe to reach it.  Big spring & piston inside.  If yours shifts fine, it may not be broken.  The simple shift kit for this model cured everything, replaced spring.  Bruce Roe

[TJ Hopland]

Just doing some follow ups on some of my topics here.   What solved the apparent rear bump steer problem was getting the rear to the proper ride height.   I replaced the rear air shocks with aftermarket ones.  Fit was fine but still had a leak somewhere so I just installed the manual fill lines that came with the shocks.  Since installation in September I have adjusted the air pressure one time a few weeks ago.   I had a full tank of fuel, full trunk of equipment and 3 adults in the car.  I need to let it down slightly again since I normally dont have that much load.  Perhaps that was one reason to make the air ride standard in these cars?  Maintain the ride height or the handling gets a little funky.