Truss Bars?

Truss bars are a triangulated arangement primarily meant to locate the frames horns to prevent them from shifting around with a high horsepower engine. Current (Greg Leach made) VMC builds use a similar adjustable rod reinforcement to tie the frame horns to the steel subframe (and he adds in a transaxle mid-mount). That accomplishes the same thing as the truss bar, so adding this will be redundant. It'll also be difficult because you'd need to remove what Greg already put there. This is deffinitely a "Juice not worth the squeeze" situation.

On the other hand, if you have an old VM built by Kirk, then it might be something you could do.

Last thing. Some think that these help accurately locate the rear suspension points by firmly tying the shock towers together. Shock absorbers damp suspension movement, but they DO NOT locate any part of the rear suspension. These truss bars do help locate the rear suspension points by firmly locating the frame horns thus preventing transaxle movement. This also helps power transfer. They use the shock mounts as a handy location to triangulate. If Greg built your car, that's already been done by tying the frame horns to the 2"x2" steel subframe that is in turn bolted to the pan.

Thank you for the reply @JMM (Michael) . my apologies, I explained it wrong. This is a VMC body that is being built by "me" so I have nothing currently installed. Ill dig into the mid mount option and see which option would be the easiest and most cost effective.

@Eric N

Eric, it sounds like you've out a lot of thought in assembling your roller VMC build! I'm sure I'm not the only one on here that would like to follow your build progress (pics) as you continue.

Best of luck!

@Eric N, Very cool! Then you can do whatever you want! I'd do both the truss bar and the mid-mount if I had anything over 120 hp. You could also copy what Greg does. He'd probably have the parts available and sell them to you if you asked for them.

Extra points for doing it yourself. You're a better man than I am.

FYI, If you go w/ a truss bar, (and not the parts not currently sold by VMC) …. I installed these on my VS.   This  retailer carries both the 1” version made in the USA sold by CBP (but a little cheaper), or a 3/4” version.

http://www.kustom1warehouse.ne...?ProductCode=17-2975

Also a good source for a few other performance bits, for less $$ than CBP. ( ex- like same brand/model high torque starters).

enjoy the build journey!

@Lfepardo I appreciate it. I love hearing user feedback! I have been buying from Stuart since day one, He is a great source of knowledge.  I trusted him to hand select all of the drivetrain components for my build.! I was actually talking to him about this kit today, and he makes makes them in house to order. He recommended the factory rubber mounts,  With a rear padded transaxle strap, and a truss bar,  for my setup. For anyone looking for straight answers, experienced recommendations, WITH great prices. Give this guy the biz!

@JMM (Michael) posted:

Truss bars are a triangulated arangement primarily meant to locate the frames horns to prevent them from shifting around with a high horsepower engine. Current (Greg Leach made) VMC builds use a similar adjustable rod reinforcement to tie the frame horns to the steel subframe (and he adds in a transaxle mid-mount). That accomplishes the same thing as the truss bar, so adding this will be redundant. It'll also be difficult because you'd need to remove what Greg already put there. This is deffinitely a "Juice not worth the squeeze" situation.

By any chance do you have a picture of the transaxle mid mount that Greg is using? I looked at a few of the recent BaT auctions by Roy of his spec VMC builds, and I see no indication of a mid mount.  Thanks.

For anyone contemplating a transaxle mid mount, there is no better than a Gene Berg, but it does take a little welding to install.

I prefer a truss bar set-up over a mid mount.  Triangulating the frame horns out to the ends does a really good job at securing the drivetrain.  To take it a step further, if you can fabricate upper mounts to be solid and part of the chassis or subframe instead of the bolt on shock tower brackets, its even a little better...

@chines1 posted:

I prefer a truss bar set-up over a mid mount.  Triangulating the frame horns out to the ends does a really good job at securing the drivetrain.  To take it a step further, if you can fabricate upper mounts to be solid and part of the chassis or subframe instead of the bolt on shock tower brackets, its even a little better...

IMO, they perform two different functions.  Mid mounts were developed to stop the breaking of transaxle nosecones. Truss bars are designed to stiffen the frame horns, to prevent flexing, which leads to wheel hop.  Wheel hop kills trans side gears and cv joints.

@LI-Rick that is exactly correct.

@LI-Rick posted:

IMO, they perform two different functions.  Mid mounts were developed to stop the breaking of transaxle nosecones. Truss bars are designed to stiffen the frame horns, to prevent flexing, which leads to wheel hop.  Wheel hop kills trans side gears and cv joints.

Especially for drag racing!

@DannyP posted:

Especially for drag racing!

I realize I'm a shaved ape with a keyboard, a corn fed white boy from Buttscratch, Nowhere USA with a hand-surgeon on speed-dial and 2 titanium knees - but who among us hasn't side-stepped the clutch and dropped the hammer on some back-road or in an impromptu race to the next right turn?

It's less impressive when the rear wheels are hammering the pavement, rather than spinning in unison in a glorious display of late-onset juvenile delinquency, a disease sadly affecting most humans with a "Y" chromosome. I know the truss-bar is meant to stop that, but a mid-mount keeps the box in one piece if something (besides the car) goes sideways.

Expensive parts tinkling on the pavement is never a good look.

@Eric N

You've got a couple of semi-related things going on, so let's go back to your original post:  You want to stiffen up the rear suspension AND mount your oil cooler in the void between the rear seat and the engine compartment, potentially using the truss bar as a mounting point is what I read.

I know that VMC mounts their coolers there, but you should also consider the left rear wheel well, too (photos below).  It provides somewhat better air flow with no hot air getting into the engine fan, is easier to get at to install the cooler and easier to service it if need arises.  The hoses are right there so adding an external oil filter just makes sense.  A big plus is that you would not need to cut a "trap door" into the fiberglas at the back of the seat area and figure out how to re-attach and seal the door.  Getting at the clutch cable adjuster is easy from below and even easier if you remove the left rear wheel.

I have a Berg tranny mid-mount to prevent lifting of the nose of the transaxle on hard acceleration (my engine supposedly does 140hp).  It works very well, at least from the feel of the shift lever.  I installed it with slight preload and you'll need to weld a couple of cushion mounts to the frame horns.  it's an easy install.  I added a 1/8" thick fender washer between the cross bar and the cushion, then bolted the cushion to the horn mounts and tacked them onto the frame, then removed the cushion and finished welding the mounts and later installed the cushions without the fender washers.

I also have the CB Performance truss bar setup (3/4"?) and it certainly stiffens things up.   I installed both of those trying to overcome a sometimes severe rear end chattering that I eventually found to be a defective clutch pressure plate.  Once that was swapped out the chatter totally went away, but that tranny nose isn't going anywhere and the whole car feels tighter.  Installing the truss bar DOES NOT affect the position of the transaxle.  The bar is mounted behind the tranny mount.

Oil cooler mount in left wheel well.  Here's where mine went:

I used a DeRale 16-pass cooler with integral fan and mount.  It sits about 3/4" off the mounting surface and cools very well, holding the temp to 200F.

Cooler and Filter test mounted.

Top left is the 180F thermostatic switch for the fan on the cooler outlet.  Later on, I went with a different fitting at the bottom that gets the hose up away from the valve cover.  Some coolers have the switch integrated right into the fan assembly so look for one of those.

@Stan Galat posted:

I realize I'm a shaved ape with a keyboard, a corn fed white boy from Buttscratch, Nowhere USA with a hand-surgeon on speed-dial and 2 titanium knees - but who among us hasn't side-stepped the clutch and dropped the hammer on some back-road or in an impromptu race to the next right turn?

It's less impressive when the rear wheels are hammering the pavement, rather than spinning in unison in a glorious display of late-onset juvenile delinquency, a disease sadly affecting most humans with a "Y" chromosome. I know the truss-bar is meant to stop that, but a mid-mount keeps the box in one piece if something (besides the car) goes sideways.

Expensive parts tinkling on the pavement is never a good look.

I was going to mention that, but then didn't. But yeah, lighting the tires is FUN! And yes, I do that occasionally. I'm still a teenager on the inside!

I realize a Spyder is different, but I do have HD German rubber bellhouse mounts, a steel trans strap over the bellhousing, and a solid nosecone mount(along with the PBS cable shifter nosecone-way stronger than the OE VW).

P.S.: This Spyder doesn't have any more NVH than my previous car with the standard nosecone and CB Rhino mounts x 3.

@LI-Rick posted:

By any chance do you have a picture of the transaxle mid mount that Greg is using? I looked at a few of the recent BaT auctions by Roy of his spec VMC builds, and I see no indication of a mid mount.  Thanks.

For anyone contemplating a transaxle mid mount, there is no better than a Gene Berg, but it does take a little welding to install.

I would visit the VMC shop now and then to see the progression of my build. I too see no use of a mid mount on mine or any other builds at VMC. I have a Subaru powered car and was wondering why it wasn't part of the build for added strength. My only thought is Greg wanted to keep the trans noise and vibration to a minimum. He does use a heavy trans mount and bell housing strap at the rear. But under heavy acceleration I think the nose cone mount wouldn't last in my car. I have been thinking I should add the mid mount anyway. Attached is my chassis in progress

Aren’t these discussions so much better than talking about what wax to use on top of your new ceramic paint protection?

@LI-Rick posted:

Aren’t these discussions so much better than talking about what wax to use on top of your new ceramic paint protection?

Are you sure we’re not related?

@Butcher Boy - I’d absolutely put a mid-mount in that, and probably a truss-bar as well.

It’ll definitely make it noisier.

Yeah, but it'll keep the front nosecone mount from self-destruction.  If you really get your foot in it the only thing keeping the transaxle nose in place is the shift rod (not cool) and the probably Urethane front transaxle mount, and the Urethane is the first to go, getting fractured and then openly falling apart.  I've had great luck running a Rhino front mount recommended by Carey Hines - 7 years now and, last I checked back in June, no stress fractures at all.   I did not notice an increase in cockpit noise after installing the Berg mid-mount, but my exhaust is pretty loud, too.

Adding a transaxle mid-mount is like a decent set of ladder bars holding the rear end of your '32.  The bars have a 3' or 4' torque arm to give them leverage to hold the rear end from twisting around on hard acceleration.  The VW transaxle mid-mount does much the same thing on a smaller/shorter scale (less HP, too).  The truss bar kit just stiffens everything up, especially for anything over 100hp.  The entire engine/transaxle is firmly held in place as a unit.  They're pretty good.  Given your Suby engine, Adding these two is about the best thing you can do.

This is great! I just ordered the mid mount, (always add items to receive the free shipping)  and I plan on ordering the truss bars to accompany rear strap. Been working on trying to find a local place to balance my rotating assembly.  I didn’t think it would be such a challenge. Blerg.

thanks everyone for the excellent suggestions and input.

@Stan Galat posted:

@Butcher Boy - I’d absolutely put a mid-mount in that, and probably a truss-bar as well.

It’ll definitely make it noisier.

Thanks Stan !!! It's on my list for this winter. I thought all along it should have a mid mount too. I think the front mount is a Rhino mount, but I'll need to contact Greg to be sure. Could be why he thought it was stout enough to handle the motor. Plus I'm older and almost wiser about getting to carried away side stepping the clutch and hammering the throttle. I enjoy spirited driving on curvy roads more than I do fixing my car. But being a bit overbuilt is not a bad thing, and I think the added noise won't effect the experience.

back in the "old days" there was a center strap mount for the transmission that bolted to the frame horns ,

The idea was that the rubber cut down the vibrations going thru the chassis compared to solid mounts ,

So is this idea  gone ?   I have driven VWs with solid mounts and they are very noisy and not fun to drive in ,  yes they had a roof for noise to bounce off  , 

Just wondering

@imperial posted:

back in the "old days" there was a center strap mount for the transmission that bolted to the frame horns ,

The idea was that the rubber cut down the vibrations going thru the chassis compared to solid mounts ,

So is this idea  gone ?   I have driven VWs with solid mounts and they are very noisy and not fun to drive in ,  yes they had a roof for noise to bounce off  ,

Just wondering

I agree, solid mounts for race cars only.  The transaxle mid mounts use rubber biscuits that can be quickly changed to aluminum if you want to race it.  I think those rubber center straps didn’t really help much, and fell out of favor decades ago.

The swing axle camber compensators also telegraph and amplify the trans noise through out the chassis.

@imperial posted:

back in the "old days" there was a center strap mount for the transmission that bolted to the frame horns ,

The idea was that the rubber cut down the vibrations going thru the chassis compared to solid mounts ,

So is this idea  gone ?   I have driven VWs with solid mounts and they are very noisy and not fun to drive in ,  yes they had a roof for noise to bounce off  ,

Just wondering

Those strap kits were for baja bugs and buggies to keep from tearing up the front trans mount and/or breaking the nose cone when the car came down after becoming 'accidently airborne".  They were (and still are) heavy, cheaply made, fit poorly and I've heard of (but have to admit, never seen) the unlined straps actually damaging the trans case.  When I was a very young man, relatively new in the hobby (and deep in the quest for more power!) and asked someone older that had been already involved with hotrodding VW's for several years about using the lined kit in a street car to stop wheel hop I was told it had been tried and that because there was so little actual solid contact area the rubber would start to wear where the top of the trans touched and it wouldn't be long until there was enough movement for wheel hop to present itself (again) and then start tearing up the stock rubber mounts (AGAIN).

At the time (mid to late '70's) the common fix was the 'traction bar' brace under the rear of the engine- you sucked the rear of the engine up ½" to take the play out of the rear trans mounts (and pre-load the frame horns to keep them from twisting) and this worked for all but the highest powered street cars.  Only problem- the mounts (especially the rear) didn't last forever with this set up either, but it was much quieter, they did last longer than if not supported and it worked better than solid mounts and/or a trans strap kit.  Berg started selling his drag race mid-trans bracket (that they'd been using in their race car with great success for years) with rubber spacers and the street crowd now had a new standard- wheel hop was non-existent, the front mount lasted (for what seemed like) forever and the stock rear mounts lasted WAY LONGER when it was all used with the traction bar.  But...

this doesn't really help us, as no fiberglass Speedster body has enough strength in the back to support a traction bar.  We still have to deal with a little frame horn twisting/movement (which, even with a mid mount, can be enough to cause some wheel hop, which if you don't know, breaks ring & pinions, spider and side gears so that's what the big deal is) and this is where a truss bar kit comes in.  As well as stopping frame horn movement it can also solidly locate the tops of the rear shocks, and anyone who road races will tell you that's a good thing.

Of course, if your Speedster is never driven hard and just used to trip down to the beach to get ice cream, never mind...

PS- @Eric N- follow Gordon's advice and take the time to put the cooler in the driver's side  rear fenderwell.  There's more airflow there so it will be more efficient.

And another PS- for any of you new to all this nonsense- the red poly replacement transaxle mounts that are available ARE JUNK!  I tore up a set in my 14 second Cal Look street car in only 2,000? 3,000? miles, and they're still selling the same sh*t 50 years later-

Note that there's no metal plate embedded in the middle running the length of the piece, which might actually give it enough strength to be useful.  The rear mounts aren't any better and both were ripped as well...

I know it's more expensive, but the Berg style mid-mount with the spacers that bolt in at both the top and bottom stops front of the trans movement up (acceleration) AND DOWN (deceleration/braking).  The mid-mounts with the red poly pads that just rest against the bottoms of the frame horns STILL ALLOW SOME DOWN MOVEMENT, and as such, can still tear up the rear mounts- it will just take longer.  As Gene used to say, "buy the best and cry once", and in this case I agree whole heartedly!

And the last thing (for now, anyway!)- both @Stan Galat and @Bruce  @aircooled (his name is Bruce- sorry bud!) built rear engine supports, which IF you have a fair bit of hp AND you like to drive your Speedster hard, is probably a good idea.  The idea is not to pre-load the frame horns like you do with a traction bar (the mid-mount and truss stabilize them and keep them from twisting) but to solidly locate the engine- one more trick to keep it from rocking back and forth on your nice stock rubber mounts and to support it's outboard weight. Here's a pic of the mount Bruce made for his Speedster, which I think is just short of brilliant, btw _{although it could use a few more holes- just sayin'}.  Sorry, but I don't seem to have a pic of Stan's creation.

That's all folks! _{(I think...for now...time to go back to bed)}

Thank you Al !.....Yes !.....The red ones are junk !  Dropped the clutch on the first chance to do so and ripped it in two !  I couldn't believe it so I dropped it again and I thought the trans was going to fall out because it was violently bouncing up and down. By the time I had everything buckled down under there, it became significantly smooth and calm on my next stop light foray.......ha ha !   Kafer bars are good too !   I ripped the "horns" out of a Baja Bug years ago so I installed Kafer bars.  Had to wear ear muffs to drive the car so I isolated then in hard rubber to reduce the noise. It was tolerable then but now I were two hearing aids.........ha Ha !!      Bruce