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I noticed that it seems common NOT to support the front of the VW engine when mounting in a Vee.............. but rather to let it hang off the 4 bellhousing bolts.
Does anyone add a front support to the engine ?
It seems like it might be a good idea to help dampen the bouncing of the engine as it hangs off the bellhousing.
Is there any reason this may be a bad idea, from an engineering perspective?
TIA............. Gary
Hi Gary I have always used a front motor mount since in the Womer cars the frame ends at the back of the engine case so no way to support the back of the tranny, So a front mount using the front lowest case bolt works fine.
A chassis that goes to the back of the tranny usually adds 15-20lbs of weight.
Ed
There were theories that a front mount put load into the engine, thereby increasing internal engine friction, and hurting engine performance.Quote:
Originally Posted by Gary Slahor
Of course, these theories are insane. If this was the case, bearing wear issues would be immediately apparent and engine destructive testing would occur. Adding a front engine mount can only be a good thing!
Thanks for the thoughts.... seems like it makes sense to provide some support.
Would there be any merit to making it a "soft" mount rather than a hard bolted connection?
Maybe rubber dampened ? to give some support without stressing the cases too much ?
Gary,Quote:
Originally Posted by Gary Slahor
You don't mention which car you have. If so we can direct you to someone who has or still makes a mount.
If you have car that did not originally come with a mount, it was probably not required.
But even my Caracal D, which does pick up the tail of the tranny, it was recommended to use a front mount.
As Ed mentioned "So a front mount using the front lowest case bolt works fine." If you go with one, you want shim it for no stress when the car is stationary. I don't think an isolated mount is worth anything.
ChrisZ
If your chassis does not require a front motor mount, then there is no other reason to have one.
1) A test was done putting a twist load into the engine at the front mount while on a dyno. No change in engine out put was observed.
2) A engine without a front mount does not oscillate.
Brian
Thanks again for the input.
For the record, I have a Protoform P3 that has a P2 subframe from the roll bar back, so the engine mounting is standard P2 arrangement.
Brian: Could you elaborate on what you mean when you say "an engine without a front mount does not oscillate"
It seems counter intuitive that an engine with an unsupported front is less likely to oscillate than one that is tied down at the front.
TIA.....Gary
Hello Gary,Quote:
Originally Posted by Gary Slahor
I designed a Vee back in 1981 that had a engine mount that allowed fore-aft movement but rigid in vertical movement. The fore-aft decoupling was to eliminate the difference in thermal expansion between the magnesium engine case and the steel chassis members. I recollect a relative movement of approx 0.040” due to the differences in CTE at operating temperature. Car is still in operation now owned by Robert Neumister.
Al Gegaregian
Yeah, except in my case. I have 2 Citations built 1 year apart and one has a front mount and one doesn’t. Go figure. I say of it makes you feel better do it. You can always unbolt it or remove it.Quote:
Originally Posted by Hardingfv32
Joe, which of your Citations doesn't have the front mount - black or orange?
I haven't seen a ton of Citations but every one I've seen has a front mount. Makes me wonder if you're missing one. Mine is a '90 and has a mount.
Hi Rich!Quote:
Originally Posted by Rich_G_SC
Thanks for letting me know that. It’s the orange car that does not have the front mount. Which is strange because compared to the black car, the orange one is a work of art, lots of carbon fiber and custom made stuff. Apparently, a lot of TLC went into the build on that one. The only thing I can figure is the engine case in that car is not the “Universal” case, so it does not have the mount boss under the crankshaft pulley. Whoever installed this engine probably chucked the mount plate due to that reason. Good thing I have one to copy! Now to find a universal case….
I made a ft mount using the lower case bolt. Made it in two parts and then bridged it in the front.Quote:
Originally Posted by housejoe
do both chassis have the “ears” on the chassis rails to bolt the mount to?
ChrisZ
I think it might be worthwhile to clarify a few things regarding this subject; there are several points that have been made but not are universal to all FVs.
If the chassis was designed to support the engine at 4 points on the transmission bell housing, the designer didn't think adding a mount at the front of the engine was necessary - the Lynx style mounting comes to mind. The chassis' that use the control arm mounts behind the trans have the option of using the rear trans mount and at least two attachments at the front of the trans. With either of these two designs, adding an attachment to the engine makes the engine a stressed component and any chassis flex (or as Al G. has noted, growth in the length of the engine due to thermal expansion) will induce loads into the front of the engine in some manner. It is possible that the addition of a front engine mount was an attempt to stiffen the chassis. It should be noted that the modifications that Al G. did to his car (starting with a Lynx), included a pivoting mount on the transmission bellhousing (think teeter totter) and therefor required the front mount to hold the engine/trans assembly at the desired angle. The design Al came up with was much more sophisticated than simply using the single mounting hole at the bottom of the case. As I recall, he did test his design on his dyno by loading the front of the engine with a bottle jack and then checking to see if there was any loss of HP - there wasn't.
-Jim
Housejoe, I have a question for you. Why do you think that only the universal case has a mounting boss on the front of the case? I have been racing for longer than I care to bring up but I don't think I have ever seen that. I have older cases here that some I use for dummeys and others I have gathered over the years and every case has a bolt under the front to hold the case together wither it is a single or dual release case. That is what I have always used for the front mount. On my cars there is a 1"x.120 wall square tube from one side of the frame to the other and it bolts under two 1/4x1" tabs that stick out from the top of the frame and there are two tabs welded to the top of the 1" that go up and the lower front case bolt I drill out to 3/8" and it slips up and is bolted to the engine there. Although it would be considered a ridge mount I am sure it would flex enough to absorb .040 movement if the engine actually expands that much.
Please I am not trying to be insulting about this but I really don't think it matters. Unless your front mount goes forward and absolutely would attempt to restrict forward expansion of the motor it shouldn't really affect anything.
Ed
Hi Chris, I had to make time to get out to the barn and look. My ‘97 Citation has no tabs while the ‘98 does…Quote:
Originally Posted by FVRacer21
Joe
Hi Ed,Quote:
Originally Posted by Ed Womer
The mount boss I am referring to is the one below the crank pulley that points forward on the Type 3 cases. I have this case in my 98 Citation and there is a motor mount plate (1/4” aluminum) that bolts between the 2 frame rails, and the a bolt through the middle to thread into that boss.
My ‘97 has the Type 1 case and there is no provision (yet) on the chassis for this front mount. And then like you say I would engineer something that would use the “cross bolt” at the bottom of the case as the connection point.
’kinda sucks though. I purposely bought 2 cars of the same “make” thinking that everything would be identical. While for the most part they are (steering,pedals/masters, rear suspension), the differences in the cage, and engine set-up (oil cooler, air ducts, etc) has really restricted the number of spare parts in my inventory that will fit both cars. I guess each Vee really is unique, no matter who built it.
The only negative in having a front mount is that you are more likely to damage the engine in a big crash. I always figured that universal cases had the extra lug on the front was for some industrial applications that the engine was being used for. Just because a car builder cannot be bothered with a front mount, or buys into the myth about loading the crankcase, does not mean that they are not a good idea. The Lynx, in particular, has massive deflection in the engine area of the chassis (in the 10s of thou just by bouncing on the transmission) which is why a front mount is helpful. I sometimes ran braces from the hoop to the shock mount, but the front mount is a better idea if the car is running vintage with a fan shroud.
The universal/type3 case has THREE bolt holes in it for an engine mount. Two are 10mm(I think) to either side of the oil pump and the lower one is 8mm. If I was to use those holes I'd use them all, not just the lower one. That's a LOT of stress in shear on one bolt and the case. You're asking to break the case if using just that one bolt hole.
The older cases obviously don't have any extra holes, and you are forced to use the front-most lower case bolt. If I was making a mount for that case, it would feature two tabs or a single U-shaped piece of steel capturing both sides of this bolt.
How does this deflection in the engine area present itself to the car/engine performance or to the driver?Quote:
Originally Posted by problemchild
Brian
ENGINE MOUNT??? That looks like an adjustable wrench!!! ;):D LOLQuote:
Originally Posted by brian styczynski
Hi Housejoe, I spoke to my friend who is a big air cooled guy and has his own general repair shop and he said the case that comes in I think the bus and also used for industrial applications has holes that face towards the front of the motor which is I guess what is the topic of discussion.
It looks like the crescent wrench photo uses the lower bolt hole used to keep the case half's together. Most of the movement I would think is up and down which is transferred from the axles into the tranny and then the motor. On the older cars and especially those who actually used the original VW pan cradle that unless the tranny was attached at the rear would allow like Greg says movement of the engine when stepping on the tranny.
One think you need to keep in mind is in order to get a FV to work especially in the front there must be a little slop or it will bind up. You kinda need to keep in mind we are not talking about a high horse power car with massive tires and down force. Finesse is the name of the game here not outright stick to the road.
Ed
Yes, the bracket uses the front case bolt. The wrench can be ignored, it was an old picture. The Lynx B came to me that way and hasn't had a problem in 5 years, that I know of that is. The engine has been opened up twice in that time.
One other thing worth mentioning- on a car with just the engine mounting at the bell housing, you should be very careful about jacking the car from under the transmission. Without a front engine mount you'll put a lot of stress on the transmission case when jacking it that way.