Jump to content
Model Cars Magazine Forum

obscure questions - march madness!


Recommended Posts

i've made up a chart that is helping me with sizes of materials. went through the scrap box and measured a bunch of materials, then cut 1 1/2" pieces and mounted them on a piece of cardstock. as time goes on and "eyeball engineering" takes over, i'll probably refer to it less and less, but for now it's extremely valuable.

then i made up a spreadsheet with dimensions in real fractions, scale fractions, decimals, & millimeters. if anyone wants a copy (6 pages), PM me.

Edited by southpier
Link to comment
Share on other sites

engine mounting. can an engine be plausibly mounted at any point along the block, bellhousing, & transmission? or only at certain points which will hold the weight - and i assume dynamic forces of the engine developing its power. can the mounts be welded, or are they all bolted?

Link to comment
Share on other sites

Every engine and transmission has its own unique mounting points designed in. Ford flatheads (with closed or 'torque tube' drivelines) for instance, generally use a 3-point mounting, with 2 mounts on either front corner of the block, and one at the rear of the transmission. The mounts are critical in an engine installation with a closed-style driveshaft (a single universal joint at the transmission, no rear universal, and no sliding splines), as much of the driving force to make the car go forward is transmitted through those mounts, as well as the weight of the engine. I mention this because many modelers completely fail to comprehend the relationship the type of driveshaft and suspension a car has to the rest of it. A flathead installed in an open-driveshaft application will still use the two front mounts (which will no longer transmit driving force) but not necessarily the same rear setup, which will depend partly on the transmission used.

Open driveshafts (2 or more universal joints, one at the trans and one at the diff, and a sliding spline arrangement to allow for varying length as the suspension moves) require the driving force of the car to be transmitted through the rear springs and whatever linkage controls rear axle movement, and the engine mounts in vehicles so equipped do nothing but support the engine's weight, prevent it from moving, and isolate its noise and vibration from the chassis.

But however the power is transmitted, each particular block design within a family will have cast-in bosses for bolts to attach engine mounts, and I always research the particular application to double-check where they are and what they usually look like. They're similar but different. What's necessary to convincingly mount an early Olds OHV V8 in front is quite different from the front mounts on a first-gen OHV Pontiac V8, for example.

Engine mounts in production or street driven vehicles usually incorporate some sort of rubber biscuit or doughnut (mmmm....biscuits) between the part of the mount bolted to the engine and the part attached to the chassis, for noise and vibration isolation. The chassis-side bits can be welded or bolted, the latter when several engine options were available in a particular body shell, or in those aftermarket installations where bolting is acceptable.

Racing cars of various types often dispense with noise abatement, and the mounts are often solid, sometimes in the original location on the block, and sometimes redesigned entirely, and becoming plates sandwiched (mmmm....sandwich) between the timing cover and the block, or the bellhousing and the block. In some cases, the rear engine mount sandwiched between the bellhousing and the rear face of the block is also the firewall of the vehicle, an integral part of the chassis.

Because of all of the variables in application and mount design, the best thing to do is to research each build individually if you're after technical correctness.

There is a sub-class of engine mounting, where the engine block itself is actually a stressed member of the chassis (see Ford Cosworth DFV F1 engine), primarily for weight and rigidity management. In some designs, longerons next to the engine carry part of the chassis loads, and in others the engine is the only frame the vehicle has between front and rear mounting plates. F1 cars have gone as far as eliminating any structure behind the front of the engine, using the gearbox as a chassis member too, and hanging the rear suspension directly from it. Needless to say, it takes some real wizardry in engineering to pull it off.

Edited by Ace-Garageguy
Link to comment
Share on other sites

good stuff; thanks. what i am taking away from this for the immediate, is that i need block support front & aft on a "driveshaft", and block support front on a torque tube. i'll grow into the nuances as i journey down the road.

now, hypothetically, if one had researched, say a '63 chevy inliner, and came up dry, could someone suggest a website that would show full mounting in clean detail?

thanks again

Edited by southpier
Link to comment
Share on other sites

..... what i am taking away from this for the immediate, is that i need block support front & aft on a "driveshaft", and block supprt front on a torque tube.

Well, sorta. I wasn't clear enough, and there are so many variables. With a torque-tube you'll still need support for the engine / gearbox WEIGHT at the rear, but the front mounts on a torque-tube setup control fore-and-aft movement as well as support weight. In a conventional driveshaft, the mounts really only support the engine-gearbox weight. To complicate the pie, some cars, like the Porsche 944, use a torque tube with independent rear suspension, so the engine / gearbox mounts in that case only support weight. There have been dry-lakes cars built where the tail of the trans is solidly bolted to the rear axle and the whole mess pivots on the front motor mounts as the rear suspension moves. Confused yet?

One constant is that there will be at least 3 mounts for the engine / gearbox, sometimes more. Rear mounts can be attached to the bellhousing, and sometimes the rear mount will be under the trans tailshaft, or one on either side of it. Like I said, it depends on the specific application.

Edited by Ace-Garageguy
Link to comment
Share on other sites

Ford flatheads, for instance, use a 3-point mounting, with 2 mounts on either front corner of the block, and one at the rear of the transmission.

The mounting tabs on a flathead Ford are actually part of the water pumps, not the block. In this photo you can see the mounting ear just above and to the left of the lower water inlet.

flathead05-vi.jpg

Here's how they look once installed in the car.

100101-vi.jpg

Link to comment
Share on other sites

now, hypothetically, if one had researched, say a '63 chevy inliner, and came up dry, could someone suggest a website that would show full mounting in clean detail?

thanks again

Well, this is where the fun begins (if you like research). I first google-searched "Chevy inline 6" and got a wiki site with the displacements and various production years. For '63, 194 and 230 cu.in. engines were common. So, I did a google image-search of "chevy 194 motor mount", and just about everything you could want is there.

https://www.google.c...iw=1563&bih=718

The next thing to do would be to do a similar run at what kind of transmissions came behind the inlines. If you look at the data in the first wiki, it tells what engines came in what cars. So, say your little six came in a Chevy 2. Search "'63 Chevy transmissions". One of your hits will be "powerglide". Seach "'63 Chevy 2 Powerglide". Yup, the PG came in Chevy 2s. Image search "powerglide trans mounts" and you get a bunch of pix of hardware, but you get an idea of what they might look like. Then image-search "powerglide transmission" and scroll through the pix 'til you see something that looks like something from the LAST search, bolted to the underside of the transmission. Jackpot...something close enough to be ...close enough.

Edited by Ace-Garageguy
Link to comment
Share on other sites

The mounting tabs on a flathead Ford are actually part of the water pumps, not the block. In this photo you can see the mounting ear just above and to the left of the lower water inlet.

Okay...I work on this stuff for a living. Daily.....not ALL flatheads mount to the pumps. For instance....

53truck_eng_frontL.jpg

But all the mounts attach roughly AT the front corners of the block.

Edited by Ace-Garageguy
Link to comment
Share on other sites

oye! this gets deep but i do appreciate the help. i'm concentrating on "period correct" gow jobs, so gratefully i can not think about all the possible variations of engine mounts just yet. next genre will be dirt trackers but just trying to get the basics down for now.

i'm okay with the flathead front mounts. in the Tardel hot rod book, the transmission looks like it's sandwiching the K member and bolting through to the little bumpy thing on the end of the torque tube.

Q: is that a correct conclusion?

now i'll go and perform my due diligence on the google* link.

thanks again

*oh, lordy - what have you done to me! gonna be a late night ............

Edited by southpier
Link to comment
Share on other sites

....in the Tardel hot rod book, the transmission looks like it's sandwiching the K member and bolting through to the little bumpy thing on the end of the torque tube.

Q: is that a correct conclusion?

Ummm, basically. There are running changes from year to year on how the old Fords were built. They were learning how to build cars by building cars, so to speak, and improvements were happening hot and heavy. The photo below is a '35 Ford gearbox, I believe, in a '35 Ford. The K-member has evolved into an X-member, but the function is the same...impart torsional rigidity to the chassis while supporting the gearbox and wishbone end. You can see the rubber mount that the gearbox pokes thru...

transmt35.jpg

...and here is a GENERAL view of the mount itself. It bolts to the chassis at the sides, and you can see one of those bolts (silver) in the photo above.

transmt3236.jpg

This is a K-member. Front of car is to the left. Trans pokes thru hole in crossmember, mount is similar to the one above, but different.

SAM_0023.JPG

Just to muddy the waters even more, this is how easy it is to mount a later-model gearbox in a '32 (or an A bone or a '33 thru '48) if the box is designed for a mount under the tailshaft....assuming an open driveshaft.....

transmt32late.jpg This trans could be bolted to a flathead and happily use the front mounts illustrated on that beautiful car posted by Drew. The front mounts are far apart enough to counter rocking of the engine due to torque reaction. This trans mount would NOT be a good idea with the more centered front mount on the truck flathead in the rusty shot I posted above. The optimum solution would be to re-work that front mount to carry out to the frame rails on either side, with a biscuit on each end.

Edited by Ace-Garageguy
Link to comment
Share on other sites

oh yeah. i guess that the transmission couldn't mount rigid or else the suspension would wreak havoc with everything in the drivetrain. i'm sorta getting this, albiet slowly.

great K frame shot, too. is the springy thing visible in the center cut-out part of the mechanical brake assembly?

thanks

Link to comment
Share on other sites

column shifting - i understand it is not used with a "top-loader" transmission, but is there any reason it could not be used in a street rod? my recollection is that it is a less positive method of moving through the gears.

pedals - swing pedals mounted on the firewall strong enough?

front suspension - Flemke. only used on race cars?

thanks

Link to comment
Share on other sites

Minor point..."top loader" refers to access to the guts when one is servicing or assembling the gearbox. "Top-shift" is the distinction as to where the linkage goes in, like "top-shift '39 Ford" or "top-shift LaSalle", as opposed to side-shift.

Ford top-loader (The internals are partially accessed through the plate bolted to the top. Many gearboxes "load" from the sides or even the bottom.) with side shifter linkage connected to a through-floor shift lever........

toploader-shftr-1.jpg?1303598351

You're correct that column-shift linkage works with side-shifted gearboxes. There was a short time when column-shift was a cool setup in customs and rods, because it was the 'new thing' in production cars. I'll check the exact time period if you want.....You're also correct that it is usually less positive feeling than a floor shifter (because of the complexity of the linkage and the need for it to change direction, and to allow for movement of the gearbox on its rubber mount, relative to the chassis / body), hence the return to floor-shift for performance applications.

Though I'm honestly not familiar with the theory or reasons for using the Flemke front suspension setup (although I would guess it was intended to allow for different spring-rates or weight-jacking on either front side, to help in setting up a circle-track chassis for particular track conditions) there's no reason it couldn't be used on a hot rod for something different. Other than the spring, it's pretty similar to a conventional solid-axle installation.

PS. Swing pedals are fine hanging from the firewall or cowl so long as there's sufficient beef in the mounting (either factory strength or local reinforcement) to prevent movement of the fulcrum during enthusiastic operation.

PPS. I did some research and apparently Flemke hit on the design by accident. Seems the wrong front spring was delivered for a race car, so to get a Q&D fix, he cut the spring in half and made up an adjustable weight-jacking rig. It worked well, and the rest is history.

Edited by Ace-Garageguy
Link to comment
Share on other sites

  • 2 weeks later...

now .... back to some "scratchbuilding" because that other thread has gotten a little out of hand.

i want to make some nerf bars for a dirt tracker. someone sent me a scan of an old magazine article that captions a photo of a front end including "... nerf bars made from concrete reinforcement...".

i thought if i rolled some .050 styrene rod between 2 coarse files i could texture it enough to look convincing from a few inches away.

Q: anyone think of a better way to make re-rod?

thanks

Link to comment
Share on other sites

  • 2 weeks later...

in the past three days i read a thread that (i think!) had a blue '32 Ford sedan with the roof cut out pictured. the poster specifically mentioned his affinity for building body framework.

having spent the better part of the evening doing just that same thing to an AMT '32 Victoria, i was wondering:

where's the post in question - i couldn't find it 5 pages into the "view new content" search thingie

and

could someone share the secrets of this apparent black art?

i struggled through it and came up with 2 good back inserts using cardstock & then styrene, but there must be a better way.

thanks

Link to comment
Share on other sites

  • 1 month later...

on the subject of detail ......... i recently read a post featuring a car with excruciatingly detailed parts in some places and very obviously overlooked basic fitting & finishing in others. i thought this detracted from the excellent work put into the areas which were finished so nicely.

i understand trying a new trick here and there, but when the grounding steps are overlooked, it brings it all down.

guess this really isn't a question afterall.

Link to comment
Share on other sites

  • 2 weeks later...

interesting comments regarding Revell's SD "rat roaster" elsewhere made me think: has anyone considered offering vacuumformed panels thin enough that the louvers could be opened up?

i imagine they would need to be made a little overscale to compensate for paint build up, but would this be possible for hood sides and trunk lids?

would just strips 'o' louvers (like the solid styrene once kit offered) be a viable alternative, with the builder responsible for cutting out the panel for flow through?

Link to comment
Share on other sites

interesting comments regarding Revell's SD "rat roaster" elsewhere made me think: has anyone considered offering vacuumformed panels thin enough that the louvers could be opened up?

i imagine they would need to be made a little overscale to compensate for paint build up, but would this be possible for hood sides and trunk lids?

would just strips 'o' louvers (like the solid styrene once kit offered) be a viable alternative, with the builder responsible for cutting out the panel for flow through?

That would be tricker than snot (or is it slicker than snot?) but it's kinda in the micro-surgery realm. I've seen a couple of guys almost unbelieveably open the louvers on some vintage 1/25 racing cars, but man, you'd have to do it under magnification ...and forget about getting the openings all the same...there are no files that small, to my knowledge. A real louver only sticks up 1/2 inch or so from the surface, so in 1/25th, the opening would be less than 1/2 of one mm.

Edited by Ace-Garageguy
Link to comment
Share on other sites

  • 1 month later...

Minor point..."top loader" refers to access to the guts when one is servicing or assembling the gearbox. "Top-shift" is the distinction as to where the linkage goes in, like "top-shift '39 Ford" or "top-shift LaSalle", as opposed to side-shift.

Ford top-loader (The internals are partially accessed through the plate bolted to the top. Many gearboxes "load" from the sides or even the bottom.) with side shifter linkage connected to a through-floor shift lever........

toploader-shftr-1.jpg?1303598351

You're correct that column-shift linkage works with side-shifted gearboxes. There was a short time when column-shift was a cool setup in customs and rods, because it was the 'new thing' in production cars. I'll check the exact time period if you want.....You're also correct that it is usually less positive feeling than a floor shifter (because of the complexity of the linkage and the need for it to change direction, and to allow for movement of the gearbox on its rubber mount, relative to the chassis / body), hence the return to floor-shift for performance applications.

......

the question about column shifters came into my head again, so i searched this thread. since the Ace offered, could we agree that an early '50s rod could sport a '3 on the tree' ? and be plausibly "correct"?

i'll be using the excellent picture to cobble together my linkage. how i get it to the stering wheel is anybody's guess!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...