Transaxle mounting

[Ruth]

Hi all,

In anticipation of the transaxle shipping, I've been looking around for pictures of how it is attached at the rear of the SL-C chassis. I've seen some Ricardo pictures, but no Porsche pics that clearly show how it attaches. I'm assuming it attaches to the crossbrace in some similar fashion, but curious how that looks with the very different Porsche mount. Does anybody have any pictures showing this?

Cheers,

Ruth

 

[Dave]

Here is how i did mine. G50-52 with side shifter conversion and flush tail housing assembly. One bolt as a kingpin for ease of removal.

 

[Ruth]

Thanks Dave. That's both very interesting, and very scary :shocked: since we have no fabrication (welding) capability. Is there no provision from the factory to mount the Porsche transaxle?

 

[Dave]

Thanks Dave. That's both very interesting, and very scary :shocked: since we have no fabrication (welding) capability. Is there no provision from the factory to mount the Porsche transaxle?

Depends on the transaxle I'd imagine, not sure which variant you are using. Fran is using some version of a 6-speed Porsche transaxle in his racecar so I'd imagine he can provide details on that one or any others he has done thus far.

At the time I bought my car, which was many moons ago at this point, there were no provisions to mount a G50-50/52 so I came up with my own. In all fairness to Fran, there are way to many variants of the Porsche transaxle to cover all bases, not to mention possible engine choices that may dictate transaxle positioning.

Howard also mounted his own transaxle and he has a g50-03 I believe. The bracket is documented in his build thread and I believe it also incorporates shifter cable mounts in the design.

 

[Cliff Beer]

Mig welding is easy with just a little practice. Git yerself a Miller 140 for about $600 bucks and you're in business!

 

[Doc Todd]

Dave, are the two holes at the forward part of your mount there in order to pass something through or just for looks/weight saving? Thanks

 

[Randy V]

While not an SL-C, you might be interested in looking at this part of my GT40 build log to see the competition transaxle support I built for my G50/03...

competition transaxle support

 

[Dave]

Dave, are the two holes at the forward part of your mount there in order to pass something through or just for looks/weight saving? Thanks

I wanted to leave open the option to possibly to pass a few lines through if needed such as oil cooler lines or water-to-air heat exchanger plumbing.

I have CAD drawings of the pieces needed to make this bracket if anyone wants them.

...see the competition transaxle support I built for my G50/03...

Looks good Randy. Similar to mine except yours mounts to the bottom. Well done.

 

[Tim]

I did my G96 this way via a paper stencil transferred to aluminum method:

The weight therefore is distributed on the upper brace and the two upright rod end connectors that go towards the floor. QA1/Summit sell the right conical washers for this. I have the same thickness mount on the front via the stock Porsche mount (I think it's even a hair thinner).

There's no adapter plate in my car, so I will be building a v-shaped mount in the middle to connect where the adapter plate would be. It'll connect the transmission to the car for a total of three drivetrain mounts. This one will be 1/4" steel, since part of the point of this is chassis stiffness as well.

Tim

 

[Ruth]

Tim,

I understand the piece you created via the transfer method. Question is, the mounting points on the crossbrace and near the floor. . .were those there from the factory, or did you create those pieces as well?

Cheers,

Ruth

 

[Tim]

Hey Ruth,

It's all stock, no welding or drilling on chassis. With this method I:
- fabricated the aluminum piece from cardboard cutout
- put in 4 screws to mount to transmission (holes are stock on housing)
- got 2 longer bolts for mounting to the steel cross brace (top left and right of my piece)
- bought 4 conical washers for either side of the top rod ends on the above bolt

My plate is about 1.5" from those little mounting tabs on the cross brace, so I wanted the rod end to be closer to the mount instead of being exactly on the cross brace. The bolts run backwards as follows:
1) washer
2) cross brace tab
3) washer
4) conical washer
5) rod end
6) conical washer the other directions (obviously)
7) washer
8) transmission mount
9) washer
10) lock nut

I don't have any pics accessible right now but will try to remember posting some later, but maybe that bolt order helps make sense...

Note that Dave's point about location is dead-on. I also have an unusual engine, so this likely isn't how things would line up for most others. Hopefully his or my method at least are inspiration for solving how yours line up.

Best,

Tim

 

[Ruth]

Tim,

For some reason, I had never noticed those tabs on the crossmember before and see them in Dave's picture now as well. Getting a piece fabricated like your aluminum is well within our grasp so I'm at ease now.

Thanks a bunch for the added clarity. I get it!!:idea:

Cheers,

Ruth

 

[Alex]

Why not just ask Fran?

 

[Tim]

Ruth,

Glad it helped. You can make this yourself. Tools I used are a jigsaw, drill and Dremel. That's it. (Ok... cardboard, pencil, marker pen as well...)

Inevitably, when you transfer form paper to metal and cut, you'll get it slightly off, so I just made sure to leave extra material I could grind and further cut down to fit. Pretty simple with aluminum - would be harder with steel.

Tim

 

[Ruth]

Why not just ask Fran?

Fran's take, according to Colin, is that its unnecessary. . . but I think Colin either asked the wrong question or Fran misunderstood the question because I can't picture the transaxle just hanging off the engine without any additional support SOMEWHERE.

 

[Fran Hall RCR]

I understood completely and its not necessary ....guys are choosing to do it and thats fine if it makes them feel better but its not a necessity.

Engines and transmission packages should only really have two sets of mounts...cantilevering a transaxle from its bellhousing is a very well known and practiced technique..even dating back to times when using the VW transaxle in mid-engined race cars was the norm....

The front engine mounts and the mid plate/adapter is all thats really required....or the engine mounts and a rear mount in Tims case (no adapter plate)...but not all three ...

Every modern formula car and LMP style race car has an unsupported transaxle...they are obviously designed to accept suspension loads too but they are also put through a lot more punishment than a street car....the 01 car has never had a third/trans mount btw.

 

[Dave Lindemann]

Fran - I'm curious, does this hold true for the Ricardo? I haven't installed the extra bracket to the "X" frame yet - is it not needed?

Thanks,
Dave L

I understood completely and its not necessary ....guys are choosing to do it and thats fine if it makes them feel better but its not a necessity.

Engines and transmission packages should only really have two sets of mounts...cantilevering a transaxle from its bellhousing is a very well known and practiced technique..even dating back to times when using the VW transaxle in mid-engined race cars was the norm....

The front engine mounts and the mid plate/adapter is all thats really required....or the engine mounts and a rear mount in Tims case (no adapter plate)...but not all three ...

Every modern formula car and LMP style race car has an unsupported transaxle...they are obviously designed to accept suspension loads too but they are also put through a lot more punishment than a street car....the 01 car has never had a third/trans mount btw.

 

[Ken Roberts]

In regards to the Ricardo I have to disagree. The transaxle is only being held to the adapter with 5 bolts in a non symetrical pattern. The Ricardo has a 8 bolt mounting pattern. I have never seen even a transmission being held to an engine with a minimum of 5 bolts.

 

[Jac Mac]

Gee, for once I can agree with Fran.. the engine mounts plus the mid/plate is all thats reqd, in fact adding the third mount at rear as some have done can induce unwanted chassis loads into the trans case that might do more harm than good. Remember the humble VW...the trans is mounted at bell housing & trans shifter cover-the whole motor actually had no mounts whatsoever.

Hmmn... Ford 289 5 bolt, VW 4 bolt, Muncie- Top Loader-, BW/SuperT10 et all 4 bolts....how hard were you lookin

 

[Fran Hall RCR]

Jac Mac has spoken......:laugh:...you have been warned...

Ken...look around at transaxle applications...many are only held on with 4 bolts...and thats all....VW Beetle all the way to the Porsche G50...Hewlands too

There was a reason I designed the chassis on my cars to work this way...and it works very well...

The three mount system can cause the bellhousing to crack in the most severe of cases...as Jac eluded to.