RF engine mount upgrade

Ross Nicol · 06-03-06, 05:30 AM

I'm just in the process of putting my power train back in the car and have come across a crappy design in the RF engine mounts.The engine mounts that bolt between the chassis and engine have an elongated hole for the long bolt to pass through and tighten onto the tube on the chassis mount.
When I took the drivetrain out I found the ends of the tube crushed and bolt/nut loose.My fix for this you can see in the photo below.I welded 16mm high tensile washers to the outside edge of the tube, ground the welds back and then painted all in chassis grey.Now the elongated holes don't cause a problem as the washer supplies a nice flat surface for it when bolt is torqued up.Good upgrade for all RF owners
Ross

Ross Nicol · 06-03-06, 05:32 AM

Oops forgot the pic

Jac Mac · 06-03-06, 07:17 AM

Hi Ross, Im not familiar with the chassis pad which the engine mount attaches to on the RF, but from your pic it would appear that the flat area in the saddle of the mount does not have a corresponding flat area on the chassis bracket on which to sit. The original chassis pads of a Falcon or Mustang take all the engine weight and the long bolts should slide in & out freely(7/16" dia bolts). If there is no flat area the engine torque will tend to twist the mount around the long bolt axis and premature failure of the rubber will result.
Regards Jac Mac

Ron Earp · 06-03-06, 09:31 AM

My RF kit didn't come with motor mounts. Jerry simply told me to get some 67-68 Mustang mounts (which are probably the same for other years) and use those, which fit perfectly. I put the engine in and out of chassis 44 twice and on mine the mounts did not rest on the chassis - all the weight was taken by the 7/16" bolts. Therefore, I got the best 7/16" bolts I could obtain to carry the load. Looks like a lot of stress on that bolt for sure but I imagine will work. Not optimal though, IMHO.

Ross Nicol · 06-03-06, 10:42 AM

Hi Jac Mac and Ron
Now the the reason for the elongated holes makes sense.It is obviously meant to allow the engine mount saddle to sit on top of the chassis mounting point and the engine torque loads to be fed through the whole area of the saddle. As Jac Mac points out the bolts then, when undone should have no weight on them and they would slide out. I have owned 2 Falcons with Windsors but never worked on the motors so I've learnt something tonight.I suppose you would have to say Roaring Forties were unaware of how the engine mounts were supposed to work too. Doesn't surprise me.the bolts do seem to be able to handle the abuse I give the car though.Race starts would most likely test them the most but going on 3 years of racing and no failures. That's a pass.
Ross

Jac Mac · 06-03-06, 06:02 PM

Ross ,you are lucky that it is a GT40 & mounted on a transaxle. If it was in a Falcon/Mustang application with linkage type throttle mechanism the usual scenario is ; mount fail's, the next full throttle application cause's motor to lift off mount pad on oil filter side, throttle now jam's in wide open, frightened driver now a couple of seconds behind impending accident. Sorry mate, its not a 'pass'. When using these mounts in high power applications it pays to drill thru the metal/rubber/metal sandwich (3/8")&install a c/s headed safety bolt.
Jac Mac.

Ross Nicol · 06-03-06, 09:36 PM

Ah yes Jac mac
I remember I used to fit a chain across the engine mount on this side to account for such a mount failure in the 240z. The bolt is not practical due to the way the chassis mount is made, have you used or seen the chain Idea before? I reckon you would have. Thanks for the inspiration on that one.It would be difficult for the whole unit to rear up like a front engine car though, as the ZF has 2 mounts on top and 2 at the rear, however it would not be good so I will fit a chain.
Ross

Jac Mac · 06-03-06, 10:57 PM

Hi Ross, Yes , chains ,wire rope, shackle's. 60> chevys had a retrofit kit for the same reason until they made the later captive type mount. I believe FORD also make a captive type as well, its fairly bulky though. I will have a look in some of my catalogs & post if I find anything. I would urge you to try & create a small platform pad if at all possible. I usually make up a small X-member with 2 Nolathane type bush's(1 ea side) that fit a U-shape lug on each chassis rail with a Thru bolt. The X-member has a piece of Angle iron on each side that attaches to the mount lugs of the block That sucker aint goin nowhere.
Jac Mac

Ross Nicol · 06-04-06, 12:12 AM

Jac Mac
I've welded a chain in as the pic shows, to the steel strap under block mounting and the other end to a piece of 3mm bar under the bolt head. This bolt is a 1/2" not 7/16" and is high tensile. That will do for now but I would like to hear of other methods you've alluded to.I have to carry on and get the rest together now it's Phillip Island next weekend and I would like to go to friday practice too, if I can make it.Should be ok.
Ross

Alex Hirsbrunner · 06-04-06, 12:40 AM

You may want to consider Prothane (P/N PTP-6-503-BL) mounts for 67 Mustangs. Most motor mounts for early Mustangs are now made in China and are of questionable quality (I have broken two such mounts in my V8 Capri). Especially true if you are buying them from AutoZone et al.

These are available from Summit (and in black). As you can see in the photo, failure of the urethane will not result in a motor mount separation. Under $100 USD.

Even though this is slightly wider than the OEM mount, it appears that it would work in this application (judging from Ross' photo)

Regards,

Al

Ross Nicol · 06-04-06, 02:35 AM

Hi Al
Yes that's a much better mount. I would suspect these mounts I've got to have Asian origin because the price was pretty cheap. They have held up ok in the 40 but this may be because the ZF mounts hold the rear of the motor pretty secure, unlike a front engine layout that has a single rubber mount at the rear of the gearbox my chain doesn't look as pretty as those mounts but I reckon it'll be effective. I had a chain over the front of the diff in the 240z as well because that mount was notorious for letting go.Ron may know about this one.
Ross

flatchat(Chris) · 06-04-06, 07:14 PM

This is what we use

Ross Nicol · 06-05-06, 12:42 AM

Geez Chris any chance of 2 of those falling off the back of a truck in melbourne. I like the stay as well, very nice stuff.Is that enough crawling?
Ross

Peter D · 06-05-06, 03:24 AM

Ross, I'd be most surprised if Chris or Peter Ransom couldn't russle up a set of mounts for you. Even though they are fairly solid urethane, I could not pick any diff in the levels of vibration / noise in mine compared with an RF & rubber mounts (and being so solid, there is no need for the RF fore-aft control link at the rear of the engine).

The gearbox stay/brace is designed for the G50 adaptor plate (just needs longer lower gearbox studs in the plate so you can run a nut into the tubular parts at the bottoms of the stays / braces). A trap is if you have a "fat" sump (like my original stock camel-hump), it is damn-near impossible to get to these nuts - a "slim-line" sump like that shown in Chris's pic solves that problem.

You will most likely need a slightly different geometry to suit the ZF ?

There was a long thread a couple years ago on this subject - whether engine/gearbox tended to split open on accel or deccel, etc. I still reckon that the braces stop the whole lot opening up if you drop the clutch on deccel, but either way, they seemed like a fairly cheap bit of insurance.

Kind Regards,

Peter D.

flatchat(Chris) · 06-05-06, 03:42 AM

This set up is a must for the SBF to G50 and are available from Peter at GT40 Australia . You probly won't need the "stay" with the ZF --- the engine mount-- yes as it helps prevent engine lift ,from the torque of the trans

flatchat(Chris) · 06-05-06, 07:38 AM

Doh! I didn' do nothin' ?
How do we delete the unwanted post?

A bit more grovelling Ross --you're nearly there

frank beuker · 06-05-06, 09:04 AM

this is what i found

Mark Worthington · 06-19-06, 10:15 AM

Quote:

Originally Posted by ahirsbrunner

You may want to consider Prothane (P/N PTP-6-503-BL) mounts for 67 Mustangs. Most motor mounts for early Mustangs are now made in China and are of questionable quality (I have broken two such mounts in my V8 Capri). Especially true if you are buying them from AutoZone et al.

These are available from Summit (and in black). As you can see in the photo, failure of the urethane will not result in a motor mount separation. Under $100 USD.

I went ahead and ordered a set of these Prothane mounts for my RF - they are very nice. Here's the problem - it looks like I didn't get both a right and a left mount...I got two identical mounts. They are asymmetric; the part that is fastened to the block has asymmetric mounting holes, with one being further from the centerline of the chassis mount and the other being closer. So I have a call into Prothane to resolve the issue. But it brings up a question: which way does the engine mount in an RF? I assume the answer is as far forward as possible.

Also, Frank, those mounts look really nice! Where did you get them?

Keith Hardy · 06-19-06, 10:49 AM

In 1/4 mile stuff, this is what we used instead of chain, to counter potential engine mount failure and stiffen up the whole assembly . From a tapped hole in the front of the block to a frame rail.