JayPoorJay

Hello all. I've gotten some pretty good advice, from someone we all know, about dropping the rear crossmember some or completely to have a much better time installing the BIG ol "513" 1978 transmission mounts into a manual 1986 S3.

I like that idea but knew the GIVER of the advice is/was tooooo busy to hang out with me and give me the step by step for the procedure... I've searched on the forum some but not found a step by step for dropping the CM specifically.

I was told and understand there are 6 large bolts. I see the 4 on either side, which/where are the other 2?

And,,, a big ol general question. Are there ANY considerations, from you all's hard work for experience, that I aughta make and take in doing this job? Anything I should be looking out for? Any tricks.

I have CV and axles and the old trans mounts off the trans at this point. I've been under it struggling like HELL to get the larger mount placed, especially on the driver's side but for the life of me, cannot. I might have just been to hot and exasperated after hours.

****AND - Thanks to the sender sent by Roger at 928srus,,, I now have a working and accurate fuel gauge!!! Very happy about that. Anywho

Any and all advice, direction and suggestions are GREATLY appreciated.

skpyle

Hello JayPoorJay,

I just finished putting the transmission, torque tube, and rear suspension crossmember back in my Red Witch. I followed Dwayne's guide. I suggest you do too.

Read this, ignore anything that is not rear suspension:

https://rennlist.com/forums/928-foru...re-w-pics.html


Good Luck!

dr bob

I'm only aware of four bolts total that hold the motor mounts on the later cars. Each mount has a bolt that goes up through a slot in the cross-member mounting ear into the bottom of the mount. Each mount has a lateral bolt that passes through the mount then threads into a boss on the side of the gearbox itself.

The lower bolts are very easy to access. The lateral bolts can be more fun, thanks to exhaust piping and shielding. For the lateral bolts, I used a universal-socket (socket with a universal joint attached), plus a couple extension bars. All 1/2"-drive pieces. That way I could extend the drive out into the rear wheelhouse area and apply some real force to it without risking tearing up my delicate but no longer precise paws.

You'll want to have a jack under the gearbox so you can adjust the height some. Loosen but don't remove the bottom bolts, raise the gearbox a little to get load off the mounts, then remove a lateral bolt and the mount, then new mount and the bolt goes back in loosely. Then the other one same way. Capture any shims that might be between the mount and the cross-member, and put them back on the same side the came from as the new mounts go back in. Once all the bolts are started pretty well, lower the gearbox and mounts onto the cross-member and torque all four bolts to spec.

Hold On

I just replaced the Trans mounts on my 83 using the larger 513 mounts on both sides. Mine is a manual, so I don`t know if the auto is any different. I did not need to remove the cross member or any suspension from car. Yes, they do require some fiddling and being a contortionist helps. Like Dr Bob says above, having a jack to move trans side to side helps. Think of the mounts as a Rubic`s Cube. As I recall, one went in from behind and below half shaft and other went in from above and in front of half shaft. You get the idea. There was a good write up by a fellow rennlister named "GUY".

jschiller

Guy's writeup:
https://rennlist.com/forums/928-foru...h-shudder.html

Mrmerlin

the 6 bolts that hold the cross member are the two bolts at each end then there are two more that are about 4 inches away from the trans mount bolts.
NOTE these hold the cross member to the chassis, look carefully, as its possible to be thinking your removing a trans mount bolt and thus be removing the chassis to cross member bolt

JayPoorJay

Good morning and thank you all!

That first link is a virtual encyclopedia of information! Thank you for posting that. Exactly what I needed to see.

I have the old mounts out and just have not been able to seem to get, move, push, pull, raise or lower the transmission enough to get that larger mount in no matter what. That day, it was 85+ degrees and by the end I was exhausted. And, what I expected to be a couple hours turned into a day. Might be that I just got to the point where I wasn't working right - effectively.

From what I can gather with very limited view is that,,, The mounts seem "precise" in the way the "lips" are cut into the mount - having to meet the casting/cooling fins on the body of the trans in a very particular way. If the fins and cuts/lips on the mounts don't meet right or well,,, well the mount won't fit. That's the way it seems anyways. I hope the mounts fit...!

I may, for a short time, try again with everything in place. I have removed the CVs at this point and they are suspended. I would like to finish WITHOUT dropping CM. Roger gave me this idea and it makes all kinds of sense. Explaining to drop it only the length of the bolts. That there are 6 of them. I, from memory,,, knew about 4 of the bolts accessible at the wheel wells. But still don't remember having ever laid eyes on the other 2. I think I have an idea of where they are now...

I could be wrong, don't even know if it's possible, but I have the sense that the entire trans (and other things) might have shifted forward 1 or 2 centimeters - mounts being undone and all - AND jacked up HIGH from the rear. Is that possible? The driver's side mount I have almost exactly in the right area but I cannot seem to line up the top bolt. The bucket (body shape) of the rear seats are in the way. Limited by the body shape on both sides the same way I think....?

I need to get back in there. This is nuts, lol

JayPoorJay

From Merlin in that Dwayne link. I will mark the subframe crossmember at all the bolt locations so that I can get things back as close to where it was IF I do in fact drop the CM some.

I will also support the trans with a strap. This should help in some of the moving side to side as well.

How much play can there be in the trans before I risk doing damage from moving it around?

And,,, from you alls experience... The 78 mount WILL work in the 86?

And, I know I'm asking a lot - but does anyone know the torques for the CM bolts on reassembly? On the mount bolts? I've learned the Allen CV bolts to be 60ft/lbs... Loctite?

SeanR

Question for others to ponder. Is saving a couple hundred dollars worth the extra trouble it takes to mount these as opposed to using the proper ones?

JayPoorJay

It's worth it to me... I might very well be in the same position with the other mounts, for one... For two, the mounts are more robust and will take the load of the trans better - IMHO... And three,,, a big 3 for me,,, is I am learning the car in the process of installing them...

In principle... I hate being gouged and tread on. I would go thru this just to NOT pay the producer of the mounts with a mark up like the one I see. There is NO reason that the "right" mount should be over 200 dollars. It's obscene. It seems Porsche (or who ever) must get some BENEFIT just because people love, maintain, drive and show these cars off in the world 30+ yrs later. "Wearing" their brand and promoting the name. It seems they might wanna support and be fair to the driver's of their machines.

dr bob

Jay --

Not being personally critical, so take this with that in mind --

Over the several many decades I've futzed with "interesting" cars, the most troubling examples were those where someone decided to "upgrade" something by substituting a cheaper part. Engine and gearbox mounts are a perfect example of this. In the front under the engine, we find some pretty elegantly engineered hydraulically-dampened mounts. The factory ones are expensive, so our suppliers have found a very similar mount that fits almost as well and seems to perform the same. My original factory Porsche motor mounts were sagging some at 15 yrs old, and at the time the Porsche replacements weren't outrageous so I put new ones in. At that point, we were experimenting with some Ford truck motor mounts that were similar spec, but the aftermarket supply varied wildly even withing the same brand and part number. Since then our suppliers have settled on a better and more consistent mount designed for some Volvo models. A few years ago I was back under the engine to solve a bit of oil sump gasket seepage, enough to leave a trace on the sump during winter storage. I pulled the still-excellent Porsche mounts and installed a set of the aftermarket pieces. The mounts that came out were cleaned and went to spares storage.

Meanwhile, the gearbox mounts were drooping, causing the gearbox to sit about 1/2" lower than design. I played with different options for adding material to those mounts, as my goal at the time was to get things back to normal height and stop the hot air flowing through the console. I used some combinations of nested hose of different flavors, on to some urethane to partially fill the cavity in the mount, all the way to dismembering the mount and re-casting the original support in a recommended urethane. Each of my attempts did in fact bring the gearbox back up to design height, but each was so firm that transmission noise was coming into my otherwise quiet cabin. A set of new factory pieces had been purchased in advance, so after my several attempts at a DIY fix the new ones went in and all was perfect again.

----

The very early trans mounts may or may not actually fit with your later crossmember and gearbox. Other will jump in with actual info I'm sure. The late mounts borrow from some technology found on some Mercedes engine and gearbox mounts, and appear to be bit more compact than the early mounts. I recommend that you support the gearbox and remove one of the factory mounts, and bring it to the bench for some dimension comparison with the old-style mounts you bought. If you decide that they should work but just need some extra clearance for installation, you can buy longer bolts for the crossmember body mounts, and swap them in one by one to allow the crossmember to drop, supported by the jack. Then move the jack under the gearbox so you can move it as needed for installing the larger mounts.

The workshop manual shows a support for the gearbox using a ratcheting tie-down strap looped over the rear anti-roll bar by the bar mounts. That method is sufficient to keep the gearbox from falling while the crossmember is removed and installed, but absolutely sucks as a way to adjust gearbox position to bolt up the mounts. Use a jack with a support block or, better, a transmission jack for supporting and moving the gearbox. My previous (in another thread) suggestion that you replace mounts one at a time means that lateral gearbox position is maintained by the still-fitted mount while you swap out the other one. Much less work especially if you are working on the ground and jackstands.


Oh, about that "gouged and tread on". Your 928 originally sold for somewhere between four and six times what the average car sold for at the time. We have the luxury of being able to buy them typically for a small fraction of that original number. But I'm constantly reminded that I'm maintaining and buying parts for my $83k (in 1989 dollars) car, not a $20k 2019 car. That's equal to over $200k today. The drop in market price is due to lots of things like costs of replacement parts and service. You saved when you bought it, but you will pay back some of that savings when you replace wear parts. My car is over thirty years old, and the model has been out of production for almost 25 years. Remind me please why the factory owes us replacement parts at 30 year old prices.

We are blessed with 928 parts vendors who work to source parts from the OEMs that would otherwise be long gone. I can't imagine trying to keep the car happy without their support. Even the factory is bringing back some critical parts production through their Classics program. But they are limited production runs of specialty pieces, parts for a specialty car that would sit on the showroom floor today at $250k or more.

The Bugatti Veyron uses a pair of 928 air filter elements. They might be the cheapest parts on the whole car. And we get to use them in our cars too.

[/soapbox mode]

z driver 88t

Jay,

I'm going to be tackling trans mounts and CV boots myself this weekend. I actually have BOTH sets of mounts purchased - the correct later OEM mounts and the larger '78 OEM mounts with longer bolts. My preference would be to use the larger mounts, not only because the were less expensive (its annoying that Porsche charges so much more for the smaller mount) but also because if it will fit, that larger mount should carry the drivetrain load with much less effort and essentially never wear out. That large mount is really stout looking..

If I discover any tricks or tips I'll try to get photos and post them.

I agree with you on getting gouged. Porsche charges nearly $1000 for a 928 Behr radiator when an E39 M5 Behr radiator is less than $200 - but that's a whole 'nother soap box.

With that said, if it turn out to be a pain in the butt, I'll just use the smaller later mounts and sell the larger ones to someone that can use them.

Good luck and keep us posted with your results.

JayPoorJay

Lots to respond to here...

---- I don't and will never take personally a thoughtful, well articulated argument or position. So, actually, thank you for your thoughts...

---- They are Porsche parts - not just a cheaper part. At core the same design. It seems (and I could be wrong about all of this) that for this reason or that,,, in this particular part,,, the shape/design of the 78 mount was different for reasons of the 'shape' of the surrounding area. And/or - Maybe, in 1978 they had a lesser material (the poly) so the size had to be, that size.... Larger. In 1986 perhaps the the tech improved and less poly filler was needed hence, smaller mount... I would hate to think that whomever is producing these 78 mounts in 2019 are using the "inferior" (for lack of a better word) 1978 technology poly ,,, in the 513/1978 mount - in 2019... Ya think?

Anyways, about corporations...
Personally, I think if you operate globally. Sell and produce as many "units" as you can,,, market like hell to convince and sell as many of these units to individual people who can afford your (the corporations) product in the 10's and 100's of thousands (millions even) where 10's, 100's and even billions of dollars changes hands over years and decades,,,, then YES you (a corporation) have taken on a MASSIVE responsibility... And hell yes you have a responsibility to follow up and thru and deal with the consequences of having shouldered and CREATED that responsibility...

I personally am not one of those who have been pulled into the mindset that I am "blessed" because a corporation (Porsche, Nike, Frigidaire, or Samsung) are doing their jobs and following thru on their responsibility...

My father was a builder, and until the day he died, if he took your money (responsibility), he was available (within reason and for fee) to follow up on what he started and keep it functional. It's good, fair, honest business.

I am so interested in the humans views on products, brands and corporations and how much credit we give them... "Blessed"?

Also, with all due respect, price adjustments over ages, in technology like an automobile, kinda doesn't work that way. If they were to sell my car as new today, a Toyota Camry has technology in it that is as or more advanced than anything on my BeaUTifulll and amazing 928 (I do love this machine). It would sit in the showroom and if they came and put a 250,000 pricetag on it - consumers would scratch their heads and say,,, whaaaa? Kinda like a flip phone in the new phone rack at an iStore...

I will work like hell and spend some doe on this machine because it is mysterious, elegant, beautiful, powerful, well crafted - I could go on - but that doesn't mean that I am going to feel grateful because some bean counter came to the conclusion that NOW is the time to JACK up mount prices because it definitely time for 84 - 88 928 owners to need to replace all sorts of parts,,, cuz the 78 wave has, or however they determine to jack up prices in preditory ways.

JayPoorJay

I will... And you me!
Thank you...

monkez

Out of fear of going off topic, I'm going to respectfully disagree here. When you purchase a car, the car company is responsible ONLY for what is required by the local government requirements for operational safety and product that the purchase entails: a working car and whatever warranty is provided on that car. However, most car companies know that if they do not make replacement parts available (or allow smaller companies to make said replacement part), then people won't buy the car due to a lack of ability to maintain and repair that car. That said, the cost of doing smaller runs for replacement parts gets increasingly expensive as cars get older because of various factors:
- low demand,
- which means smaller quantities on production runs
- which means fewer items to cover overhead costs (which increases cost per unit)
- which means more items taking up space in storage until the item is finally sold (which increases cost per unit)
- which means less ability to sell product that is in higher demand because lower demand items are taking up space
etc., etc., etc.

This isn't a defense of car companies, but rather just a round about explanation stating that car companies don't owe us jack sh** and well pass any responsibility for these cars, actual or implied as it pertains to replacement parts on a 25-40 year old car.

More importantly, this should be taken as a point to make sure that we buy product from the sponsors of this website because they provide viable parts at reasonable prices (despite our perceptions to the contrary) to keep our beloved 928s running. Their prices are not high because they want to gouge us, but rather they need to cover their costs and make a profit that allows them to stay in business. When they buy inventory to sell, that inventory takes up space, which requires rent, which takes up capital (ie, cash) that cannot be spent until said inventory is sold. The more often we buy our parts from our sponsors, the better off they are and the longer they will be in business.

I apologize for the spontaneous stream-of-conscious soapbox diatribe, but wanted to point this out as we ARE very lucky to have the 928 vendors that we do have.