Motor mounts or springs? maybe both?

[phil_long]

Good morning gents! There is no better place to go for legit advice and good convo than here. I just installed a new DP on my car and noticed that it sits on my A-arm a bit. I thought it was an issue of the new DP, but then I looked at my stock DP and noticed a dent around the same area. Needless to say this is an issue, so I'm wondering what needs to be done to fix this? I'm confident that the motor mounts have probably never been changed, and my springs are super shot. What do you fine gents think?

[Steve Wood]

I would guess mounts are the first guess.  Open the hood, start the car, foot on brake, car in drive, ease down on gas pedal.


Does the engine jump up and roll to the passenger side when the rpm gets up around 1200 or so?

[phil_long]

I'll check after work to verify. If it does, that means that both mounts should probably be replaced?

[Steve Wood]

yep///


Particularly after 30 something years

[good2win22]

If you decide to use the HR mounts, you can adjust them ever so slightly to get a little more clearance on the down pipe. With that being said, once clear on the a arm, look at the pinch weld on the body firewall where the down pipe squeezes between the starter and the HVAc box. You made to clearance the pinch weld

[TexasT]

Bfh to the pinch weld.

[phil_long]

Understood. So are the springs a possible issue as well? I mean, my car sits really really low due to worn springs.

[Steve Wood]

Phil, my brain is foggy this  morning and I am not sure about the affect of the springs.


I can tell you that I have Eibach springs on my GN which drop the front about 1 inch and my T has regular springs.  I just went out and looked at both.  Both cars have about a 1/2" clearance from the bottom of the three inch down pipe to the rear ear on the upper control arm.


Looking at them reminded me of something to check, however.  Be sure the rear bushing in the passenger side upper control arm is good.  If it is worn out which is very common due to the heat from the down pipe cooking the rubber in the bushing, then things can start rattling in a hurry and you will normally notice the sound when driving.


If the engine mounts are worn, the engine will sag down and move around and that usually let the down pipe start banging the control arm under acceleration.  Both of my cars have one poly mount on the driver's side and one regular mount on the passenger side.

Also check the transmission mount...if it is bad, it will allow things to touch that should not touch.


The knock against poly mounts used to be possible vibration as the material was too hard so we used just one for street cars.  I heard a rumor that someone had developed one with a bit softer poly but Jason, or someone up to date will have to answer that.

Okay, I went and looked.  Full Throttle advertises the second gen poly mount which will reportedly handle over a 1000 hp and are reported to be softer and vibration three.  They ain't cheap, but, they are forever.


The other thing that can cause problems are worn out body bushings which drop the body down further.  That can be seen most likely at the pinch weld that was mentioned above.


If you want the car to drive right, then pop some new springs on it!  Worn out, sagging springs do nothing for ride quality and handling.!!


My guess is mounts and body bushings will have the most effect on clearances, springs will be the most noticeable in driving.  Bilstein shocks are the way to fly on shocks for best handling and comfort on the road.

[phil_long]

Thank you so much for you response Steve. Looks like my car will be a garage queen again for a bit. Lol. Between the mounts and the body bushings, I have a ton of work ahead of me. Hopefully I can do the work myself to save some money. I'm ok with spending the money on the motor mounts if they last. I'd prefer not to have to do that job more than once.

[phil_long]

I'll see if I can find some instructions on youtube or something on changing those motor mounts out

[phil_long]

Also, I'm very unfamiliar with what this pinch weld is that you all speak of. I'll ask one of the guys here to show me. Thanks again for your help. You are the man as always

[Steve Wood]

the mounts are usually pretty easy.  When you get the new ones, we can help.  You do one at a time and the drivers side is very easy.  Most of the work is done thru the wheel well after you take the tire off.


the pinch weld has never hit any of my down pipes but I know it happens.  If you get under the car and look up between the starter and the ac box as Jason mentioned, you will see where the firewall comes down and is welded to the floor pan as I recall.  There is a vertical lip sticking down at the seam between the two...you can massage it with a hammer and bend it over to gain more clearance where the pipe passes by.


The problem that many have is not fixing the basic stuff that is worn out because that is not as much fun as putting a turbo on, or such.  The cars always run and drive better with the basic stuff fixed.