Questions about a possible motor mount DIY

[sugarwood]

I'm really enjoying this forum, and it's helped me (eventually) successfully tackle a few basic projects so far.
(Alternator fan felt, heater footwell motors, 915 Kendall gear oil change, Leland's steering wheel bushing, etc)
This weekend, I'm going to attempt installing a new high beam stalk & dash light fuse.

I'm a beginner, and I like to ask a lot of questions. Thanks to those who like to guide us n00bs along the path to auto enlightenment.

Another project I am researching is the motor mounts.
1) On acceleration, sometimes the shifter eagerly snaps out of 1st when I go to shift to 2nd. Like there is tension pushing on it. Otherwise, my 915 shifts great.
2) When I accelerate, and let go of the pedal, I sometimes hear a rattling in the back. If I immed. step on the gas, it goes away. This tells me the rattle is when the weight shifts forward when I let go of the gas.
Do these symptoms sound like motor or tranny mounts?

First, I am wondering how the motor mounts even work on a 911. Is my understanding correct?
On other engines, aren't the mounts under the engine? This configuration is self-evident. The engine rests on these rubber dampers.
But, in the 911, the mounts appear to be suspended above the engine. The cross bar is mounted to the engine, and the motor mounts dampen the cross bar?

If I proceed with this job, are there any general pitfalls or tips & tricks to doing this job?

Is this a 2 man job?

Is there a fitment issue with what Pelican sells? I see a few bad reviews.
Project 27: Replacing Motor and Transmission Mounts - Page 2
Which one do I get? Do I want stock or sport mounts?
I do not drive very aggressively, and don't track it. Weekend fun car.

It sounds like getting the small bolts started is tricky?
Use tape and box end wrench to get the nuts started underneath?
This guy had trouble securing the smaller bolts underneath.
So did this guy.
Motor mount install - or how to bloody your knuckles

This guy ended up bending his motor mount bracket.
How will I know if I am damaging the cross bar?
Is this a common risk? If so, I'd prefer to leave this to a professional.
A new cross bar is about $125, but does this require dropping the engine to replace?

Is it difficult to get the bolt back into the cross member?
88 Cab motor mount replacement

Thanks Pelicans!

[steve911T]

I removed the rear engine crossbar to drop the motor down and in my opinion, it was a piece of cake. You obviously need a jack to support the motor but on a scale of 1-10, about a 3. This was on an 89 Carrera. Steve

[Oh Haha]

It could be your engine mounts causing the shifter issues. IF they are worn, along with the gearbox mounts, they could be allowing too much movement.

This id certainly a DIY project and given that you've done the other jobs this should be an easy one for you.

There are basically 4 mounts holding the engine and gearbox in place. 2 at the engine, which you've indentified, and 2 at the gearbox crossmember. All 4 are the same and are interchangeable.

You can find in depth instructions doing a search but I will give you the bullet points:

Support the engine with a jack or jackstands and remove and replace with new just ONE engine mount at a time replacing with new but do not tighten fully until both new ones are installed. Keep the jack in place the entire time.

The gearbox is the same procedure albeit not a whole bunch of room under the car. If you have a lift life is MUUUUCH easier. I dont.


As far as the new mounts--I have sport versions and like the firmness of them. for the few extra dollars it is a worthwhile upgrade. Get the same for the gearbox and you will feel the difference on the first drive.

[garment]

I put in Wevo black pillows in January of this year, after about 2 years of ownership, which replaced what I assume were the original mounts. The engine mounts were finicky b/c of the difficulty of getting to the nuts under the engine supports at either side of the engine bay - you'll see what I mean when you get to it. Use a stubby box wrench underneath and a ratchet up top to get rid of the old mounts. I didn't take off my A/C compressor.

Re-inserting the large bolt on the driver side through the mount and into the engine support was a bit finicky too - when I removed the original bolt, the cross-mount kind of sprung forward of the motor mount - toward the front of the car. I had to push it in place and drop the bolt in, not that difficult, but definitely unexpected.

Tranny mounts were easier, but make sure you are clear of any lines when you jack up the tranny, and only jack the tranny as much as you need just to allow the jack to take the weight - no need to lift the car at all.

I went with new bolts, but I am picky.

Change in shifting was marginal, but noticeable. I am glad I did it - the old mounts had the pliability of hockey pucks.

Good luck! And next try replacing the rear shocks if you want an exercise in working blind with a wrench and only room enough to undo the nut a 1/8th turn at a time...

[sugarwood]

I looked at my engine bay today.
Wow, I could barely get my hand under the little shelf the mount sits on.

I read an old thread where the guys motor slightly shifted (or the mounting bracket arm bent)
but, now I understand how you'd never be able to re-thread the bolt back in.
It's totally blind, and if the bolt just can't find the hole, I'm not sure what I'd do in that situation.
Keep jigging around until the bolt catches?

Due to the tight fit and exact tolerance, changing the motor mounts is a little more intimidating than I anticipated.
It seems like it can be simple when everything goes right (best case scenario),
but a huge headache if something goes wrong (can't get the new mount bolted in, rendering the car undrivable)

[DaveMcKenz]

Finicky is a good word for the motor mount change. Only one mount changed at a time will keep shifting to a minimum. I taped my nut to a box wrench then positioned it under the hole to mount the motor mount to the shelf. Not too bad.
Good luck,
Dave

[Typ616]

Honestly changing engine and tranny mounts is a pretty easy job on those cars, not much harder than changing your oil. You unbolt and bolt back a rubber disk that has a nut, bolt and a couple washers... There is no real head scratcher other than the order and direction of washers which you can deduce from removing your old ones ;-) You simply must take care to support whatever you are messing with (tranny or engine) with a jack (or 2 jacks plus another for safety when it comes to the engine, tranny won't fall on you if the jack fails, but the motor will!), and like others said do one side at a time to make your life easier... It really is not hard.

But I remember from my early 911 days that I was experiencing the same symptoms as you when I was mis-timing my shifts, because I was used to faster trannies. If you are still on the gas a little when moving the shifter, it could do exactly that... If I were you I'd try shifting slower and decomposing a little more (still under acceleration, just count 1 mississipi, 2 mississipis ;-) and see if it still does that... If not, you simply need to re-adjust your brain to a slower gearbox... before you pay some money for possibly un-needed mounts. Engines are more likely worn than tranny from what I've seen on my cars, and you can see them better too, but could be just my cars.

PS: reading the "finicky" comments above, I must have gotten lucky. I don't mean to doubt those guys, it just worked for me easily on a 911SC and on a 993. No trick, just supporting the motor to the point of slightly lifting it one tiny bit, and using the jack to realign it all... butter... Out, in, on with your life. As for the material, I wanna say go factory/go soft unless you have a reason not to. All the fancy shiny hard stuff transmits all the vibrations into the car and if you liked your car as it was, don't go hard. Again just one guy's opinion.

[sugarwood]

Since I can't actually see them, I can not tell if they are dry rotted or cracked.
Is there any way to diagnose the motor mounts without removing?

Also, if one wants to pre-lube with PB Blaster, is it possible to get underneath at the arm bracket mounting hole? Seems like the top is sealed off.

[SoCalSK8r]

The hardest part is holding the nut and washer in place while reattaching the motor mounts.

I have small hands and it was still a struggle but doable. Tape is your friend for this one.

Getting PB blaster on those nuts would be tough but perhaps with a long enough straw it would work.

Remove the black heater pipe as that greatly increases the access.


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[sugarwood]

Ok, I now understand the comments about holding the bottom nut in place.
For each mount, the one closer to the rear/center of the engine bay (just blocked in the photo) is almost blocked by the mounting arm.
It's not too bad to stick a finger in and touch the nut, but re-threading would be tricky.
I agree that taping the nut to your finger or wrench would help you position it for the bolt.

That large bottom washer just needs to be position that for the large bolt, right?

What would be the correct order for removal?
Remove the 2 small side bolts first, then the main center one?
For re-installation, main center bolt, and then the 2 side bolts?

[SoCalSK8r]

If you remove the sides before you remove the center, the mount will twist when you remove the center.

Break all 3 free. Remove center and then sides.

For installation I think I did center first (very loose) then the 2 small side screws. Last step is to snug up and torque.


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[tadink]

Originally Posted by SoCalSK8r

If you remove the sides before you remove the center, the mount will twist when you remove the center.

Break all 3 free. Remove center and then sides.

For installation I think I did center first (very loose) then the 2 small side screws. Last step is to snug up and torque.


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Agree on the side nuts and access - I wound up wrapping some tape around the nut and lock washer, and then around my FINGER to hold the thing in place while I turned the bolt to start the threads....worked great for both sides, inner bolts on my 89 Cab.

you mention 'torque'' - what is the correct torque for the motor mounts large center screw? I could not find that number anywhere....

thanks
td

[Driven97]

I would focus on the trans mounts. The crossbar the engine hangs on is "floppy" in the fore-aft direction. It only locates the motor in the vertical and lateral directions.

[DRACO A5OG]

If I may Suggest Sugarwood:

Raise the car, place on jack stands then lower the engine so the mounts will have close to neutral load as possible. Remove main bolt then the two smaller ones and replace in reverse order.

You may need to push or pull the crossmeber to align the wholes but do not worry this is normal.

It really is a snap to do.

Now the trans mounts that is another story, you have to make ABSOLUTE sure you do not cross thread, chassis nuts are super soft ( alignment is about the same thing. pull and push to align ), hand tighten then use torque wrench.

Jim

[sugarwood]

Jim,
Even if I knew how to lower the engine (would love to learn), did you mean put the car on jack stands and RAISE the engine so there will be neutral load? Doesn't the engine hang from the motor mounts? I would have thought I'd need to put jack support under the engine, pushing upwards, to remove the load from the mounts.

[sugarwood]

UPDATE: Today, at the shop, the mechanic said my tranny mounts are shot.
He was able to use a pry bar to move the tranny up and down, while he pointed out a gap above the tranny mounts.

I will try replacing them and see if that resolves the shifter sometimes popping out of first when I go to shift to 2nd (when I let go of throttle, and weight shifts forward)

New question. If the shifter bushings and linkage have been adjusted to accommodate bad tranny mounts,
can replacing tranny mounts require you to readjust your shifter linkages?

Does it matter much if I install sport or stock tranny mounts? I only plan to attend DE maybe once a year.

[DRACO A5OG]

Hey Sugarwood,

Yes, after you raise the rear end and on jack stands, raise the engine using a pad or small telephone book as not to marr up the engine using the jack to raise her to keep the engine on a neutral load.

Yes, engine hangs from the motor mounts, raising the engine relieves load on the mounts while on jack stands.

On the Gear Box Mounts, just make sure the hole is properly aligned. Use Cabriolet Motor/Gear Box Mount for the gear box you may get a more precise shifting

Yes, you may need to re-adjust coupler.

Jim