Driveshaft length problem from FFR / Gen 3 Coupe delivered April, 2021

[MAHunt]

Has anybody had a problem with the driveshaft length supplied from FFR with the new Gen 3 Coupe kit. I have a Gen 3 Coyote with a Tremec TKO 600 5 speed and a Moser 8.8 solid axle rear. The supplied driveshaft (P/N 60452) was 3/4" too long, couldn't even get the rear up to ride height without crushing trans tail-house dust boot (driveshaft measured 15.75" from flat of slip yoke to the mating surface of the pinion flange - FFR's way of measuring).

First, I thought the engine mounts may have been welded in 3/4" to far to the rear because of the drive shaft, but also because the tunnel cover shifter hole was exactly 3/4" to far forward, and the Trans mounting plate was exactly 3/4" to far forward to hit the center of the mounting slots. FFR tech assured me. that ALL engine mounts are the same on Coupe kits. They said I had the wrong driveshaft.

The replacement FFR sent was only 13.25" (P/N 16349) and only provided an insertion of the slip yoke of about 1.75", not nearly enough. The tech dept. said there was no driveshaft length between the two measurements.

This is my third FFR car build (2005 - Mark III Roadster w/ '91 5.0, T-5 & Ford 8.8 solid axle rear, 2016 '33 Hot Rod w/ Gen 2 Coyote, 4R70W auto, & Moser 8.8 solid axle rear). Never had any problems like this with driveline, always + or - .25" with just about perfect slip yoke insertion.

I would greatly appreciate any thoughts or possible solutions. Looking like I will have to spring for a custom made driveshaft.

Max Hunt
Gen 3 Coupe #298
Gen 3 Coyote, Tremec TKO 600, Moser 8.8 Solid axle.

[David Williamson]

I would talk to FFR again to sort it out, you have a common drive train. Dumb question but are you sure the engine mounts are on the correct side?
My early Gen 3 coupe #16 had issues with the engine mounts welded reversed to the frame, ended up with 3 sets of engine mounts and 3 drive shafts to get everything sorted out and the engine in the correct location. After mine they changed the welding jig so it can't happen again.
David W

[MAHunt]

David,
Thanks for the input. I'll definitely check it out, but frame mounts and engine mounts look to be OK. Still sending pics and sketches to FFR. Hope to find out what the problem is. Like you pointed out, it is a pretty common drive train combo.
Max

[lewma]

Max

Please keep us updated on what you find. I'm having issues too but probably self induced. I'm building coupe #309 using a Blueprint GM427LS with T56 Magnum transmission and IRS. My transmission rubber mount is about an inch too long past the end of the transmission mount plate. Going to get the IRS installed tonight now that I received the backordered bushings. Definitely need to address the transmission mounting plate but I hope my driveshaft fits.

mark

[MAHunt]

Mark,
Will do on the update. Still waiting on someone at FFR who knows the drivetrains to look at the pictures I sent. Will be interested to see how your measurements come out after IRS installed. Max

[lewma]

Max

We dropped in the engine/trans/driveshaft and hooked it up to the IRS. It's tight but it seems to fit. The only issue is the transmission plate. My son is designing a new transmission mounting plate that we'll send out to get laser cut. Just got to find a vendor somewhere that can take his cad files and whip up the plate.

Pics can be seen in this link. Its all loosely coupled together at this point. Still got to get everything lined up correctly. But at least it seems to fit.

https://photos.app.goo.gl/EghMwuGfN81fQiHi6

mark

[MAHunt]

Thanks for the input Mark, Still not getting any help from FFR. The new Tech/parts customer service rep told me I need to take the longer driveshaft I have to a shop to have it cut down to the size I need. Seems like it should be their problem and not mind, as I paid for a compete kit with a pretty standard drivetrain. The service rep did say he would send my pics and sketch to the engineers, but it may take a while??? Not too happy right now.
Max

[lewma]

Max

I hear you on the lack of help from FFR. On one hand they were very fast in getting me replacement side pipes for my MK4 a couple weeks back, but getting any help from them regarding my coupe kit is very challenging.

[Erik W. Treves]

maybe posting pictures here would be of some benefit - there has to be something we are missing here since this isnt an abnormal setup . The second shaft they sent you that only engaged 1 3/4 was that at ride height?

[MAHunt]

Erik, Doesn't look like any further help on this issue is coming from FFR. They seem to be reluctant to have engineering contact me. They basically told me to have the longer driveshaft (shipped with the complete kit - 15.75") shortened, which I am planning on doing at this point. The second driveshaft they sent and said was the "correct" part is shown in some attached pics. Thanks for the response.
Max
150194150195150196

[lewma]

Max

FFR engineering is also supposed to be looking into my fitment issues too. FFR already told me that the department is out of the office for a few days next week so I'm not expecting any reply any time soon.

mark

Update: Looks like a new transmission plate design is needed

[Erik W. Treves]

can you add some pictures of the engine mounts as well?

[65 Cobra Dude]

We talked about this in London and I think you may have rebuilt your motor mounts incorrectly. Easy to do and difficult to detect. As Erik said, post some pictures of the motor mounts that you put the spacers in.

Henry

[Erik W. Treves]

the transmission looks like it's too far back? how is the tranny poly mount laying on the chassis mount? it should just about land right in the middle of the slots.... hard to see

[MAHunt]

Henry & Eric,
The poly mount on the transmission is exactly 3/4" too far back from the center of the slot. Had to file the back of the slot a little to get the mount bolts in. In regard to the engine mount spacers, everything went together exactly like manual presented, and there didn't seem to be any way a "front to back" dimension error or 3/4" could be made. I attached a couple of pics. Thanks for your thoughts - still leaning toward having the longer driveshaft shortened and balanced. But I will wait to see if anything comes from FFR engineering.150365150364

[Erik W. Treves]

ultimately the shortened driveshaft will work (obviously) - but the tranny slot being 3/4 too far to the rear is telling I think because if you were farther forward at the tranny the longer shaft would have fit? off chance which bellhousing are you using

[edwardb]

FWIW, I just checked my Gen 3 Coupe with the Gen 3 Coyote and same Energy Suspension mounts. I can confirm mine is exactly like your pictures. Bolt through large slot toward the front. Pin in smaller slot toward the back. So the chassis mounts appear to be correct. And the motor mounts are on the correct sides. Wouldn't fit like that if they were on the wrong sides. So this possible error condition is eliminated IMO.

I can't help with the actual driveshaft length. Mine is T-56 plus IRS. The FFR supplied 10.625" driveshaft fit OK. I did have the fiddle around a little with the transmission mount. But that was because the shifter hit the underside of the transmission tunnel. But the bolts lined up OK. But none of that is any help to you. Sorry. Hope you get it sorted. Just hard to believe your very standard configuration doesn't have an easy answer.

[MAHunt]

Thanks to everyone for all the posts and interest in this. Right now iI'm going to have the driveshaft shortened. don't see any other option. I will return and post anything new I get from FFR. Thanks again.
Max

[LateApex]

This is an interesting thread. "Interesting" in a Chinese sense of the word:-) I have been wrestling with fitment today.

I am building a complete kit Type 65, August 2021 vintage. Just installed motor and tranny (Blueprint 347 with Tremec), also with Moser 8.8" rear.

Installation was a bit of a grunt. Tranny mount holes did not line up well after I got the engine mount pins centered. I had to loosen everything up and add a bit of cherry picker persuasion to move the engine / tranny aft so that I could gain thread traction on the tranny mount. Very front of the tranny mount slots. Everything is cinched down now, pins on the engine mounts are well centered, but the engine is a bit skewed nose right (something maybe only I would notice), and I spent three hours today hooking the cherry picker back up and using more persuasion because I forgot to attach the engine ground strap to the PS engine mount, and when I loosed that bolt, it sproinged (okay, I can invent one word ...) and the holes did not align, and ... well ... The whole system is a bit under tension IMO, which doesn't make me comfortable, but these are "plastic" mounts, and they will adapt faster than I do.

But that is not the topic ...

After torquing mount bolts, next up is driveshaft. I am not sure how a drive shaft is measured. Mine is P/N 16349. The space between Moser yoke and tranny tail (aluminum), as shown in one of the photos above, is 14". 14" is kinda loose, as I am using a Panhard rear end, so I can trade off alignment for distance, or put differently, I have not verified "square" yet. This set up is snug, like 1/8" gap between driveshaft and tranny rubber seal. I can deal with that I believe.

And then I find the 12 point M12 x 1.5" yoke bolts are too long. At most, they should be 1", else they interfere with the Moser nose.

Was going to be checking off a couple of minor build items. 4 hours later ... ;-) Gotta find shorter bolts. Yep, I am slow it seems ...