IRS Pumpkin / Differential Install

[Rodster]

I know this is an old topic, since I read as many posts as I can find on both forums.

But - my differential looks different from others, and so I decided to post a fresh look at this.

My standard width IRS differential did not fit into the cage as documented in the manual - and the Forum posts. To cut a long story short - remove the rear cover.

Here are some pictures - more pictures and details are posted on my WordPress blog site. (http://wayneyoshida-kh6wz.com/)

Skip all the complicated directions, and just take off the cover. Then you and your helper can use the jack to lift it into place:

15320

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By the way – anyone else missing two nuts and bolts for the pumpkin mount? My parts list is correct, and yet I am still missing two fasteners for the standard width IRS differential.

-wayne

[flajctype65]

Looks the same as mine. 1 person job is almost impossible to get it in without taking off the cover, but with a helper, following the well established movements, takes 30 seconds.

[Jacob McCrea]

Thanks for mentioning this. The difference is the new Motorsport cover with carrier bearing preload screws. The old factory cover is not nearly as large and does not interfere with the rear mount when you are trying to put the differential into place. The new cover impacts the rear mount. Had I known this I would have left the cover off, as mentioned in post 17 below. I eventually got it through the frame, but it was very difficult and I will separate the two in the future.

http://thefactoryfiveforum.com/showthread.php?4257-How-much-horsepower-is-reasonabe-for-an-IRS-coupe

[Rodster]

Regarding the nuts and bolts for the IRS pumpkin - I found them this morning. Two nylon lock nuts and two bolts (1/2-13 x 3.25-inch) are in the 12438 bag, in Box 11C, IRS STD Width Rear Suspension.

The other two are included in the "IRS Completion Package" and are part numbers 25995 for the flanged locknuts and 14952 two bolts. I am not sure why these are metric. . . .

This is what they look like, the nuts and bolts from Box 11C are at the 5 o'clock position.

15367

[CraigS]

A bunch of the solid axle stuff is metric too so I assume they just follow whatever Ford did originally. Sometimes a 1/2 inch will fit and sometimes not quite.

[Rodster]

Jacob -
I just read your post - nice work as others have said. I like those safety-wired hollow bolts. My car will be a weekend driver, so hopefully the standard parts will be fine. My plan is to stick to my budget as close as I can (Yeah, I know), finish the car and drive it - then make upgrades and modifications after.

Of course, I think others may have started this way, too - and then decided to just build another one - which is already what I am thinking.....

Wayne





Thanks for mentioning this. The difference is the new Motorsport cover with carrier bearing preload screws. The old factory cover is not nearly as large and does not interfere with the rear mount when you are trying to put the differential into place. The new cover impacts the rear mount. Had I known this I would have left the cover off, as mentioned in post 17 below. I eventually got it through the frame, but it was very difficult and I will separate the two in the future.

http://thefactoryfiveforum.com/showthread.php?4257-How-much-horsepower-is-reasonabe-for-an-IRS-coupe

[Jacob McCrea]

^Thanks Wayne. It looks like you are making really solid progress. I appreciate the photos and narrative.

As for the metric v. standard threads, my understanding is that the differential mounting bolts, as well as the steering rack mounting bolts, are metric. I ran a 1/2" drill bit through my solid aluminum rack mounts, the rear diff cover holes and the solid aluminum front diff mounts (a very good idea as soft front mounts and solid rear mounts probably don't mix) so that I could use those 1/2" hollow bolts. The next time I work on a half metric, half English piece of equipment will be too soon.

[teesalmon]

After making a special wooden fixture to sit on my jack, and struggling for at least an hour with a helper, thinking this was a Chinese puzzle, and there was a way to orient the pumpkin, I have determined, it's not gonna happen. I'm not sure why the rear mount has to be welded to the frame. It it were a beefy, bolt on mount, this would be a much easier task. Maybe by design the thing will fit, and my IRS section is not to print by 3mm somewhere. It won't install in the suggested assembly process.



I know this is an old topic, since I read as many posts as I can find on both forums.

But - my differential looks different from others, and so I decided to post a fresh look at this.

My standard width IRS differential did not fit into the cage as documented in the manual - and the Forum posts. To cut a long story short - remove the rear cover.

Here are some pictures - more pictures and details are posted on my WordPress blog site. (http://wayneyoshida-kh6wz.com/)

Skip all the complicated directions, and just take off the cover. Then you and your helper can use the jack to lift it into place:

15320

15321

15322

15323

15324


By the way – anyone else missing two nuts and bolts for the pumpkin mount? My parts list is correct, and yet I am still missing two fasteners for the standard width IRS differential.

-wayne

[teesalmon]

I would like to respectfully retract some of what I said. I still believe a bolt on mount would make this an easier task, but I was able to install via the build manual process. See thread, " help with IRS Installation #7967 in Roadster". It was a matter of whether the top or the bottom of the pumpkin faced the passenger side of the vehicle when lifting the pumpkin in the nose up position. When I realized the situation was not symmetrical due to the rear cover mount not being on the centerline, I flipped the pumpkin around and it actually went in without too much trouble. I did not have to remove the cover. Note I am using the stock aluminum cover.
Installed in this orientation:37654
Did not install in this orientation:37655

[CHOTIS BILL]

Rodster, the reason you had to spread the ears to get the rear cover to fit is that the HD cover rear mounting pad is about 1/8” wider than the standard cover. Most people I have seen using the HD cover mill the pad down to the same thickness as the standard cover. Thanks for the pictures because I am going to be changing my cover in the near future and the pictures clears up questions I had about doing the project.

Thanks,

Bill Lomenick