8ba flywheel to '39 trans question??? Help!

[562Roadster]

I've been reading alot about the 8ba to '39 trans combo. I'm missing the flywheel, and now I'm learning that I need to get the correct flywheel either for a car or truck?

I thought all 8ba flywheels were the same. Anyway, what do you guys recommend? Should I locate a car or truck flywheel?

Any help would be much appreciated.

Thanks.

[waltere]

I used a 49-50 Merc flywheel and presure plate. That gave me the correct diameter for the clutch disc.
Walter

[19Fordy]

Originally Posted by waltere

I used a 49-50 Merc flywheel and presure plate. That gave me the correct diameter for the clutch disc.
Walter

So did I, for my 40 Ford trans. I think I used a 10 in. 1946-48 Ford truck clutch.

[Mac VP]

If you have a late style V8 (49-53) and you want to connect it to a 39 style trans, you need either of two clutch setups:

A) 1949-50 merc clutch (10" Borg & Beck type) along with the Merc flywheel that has the same bolt pattern for the 10" B&B pressure plate.

B) 1949-53 Ford clutch (10" Long type) along with the Ford flywheel that has the bolt pattern for the 10" Long pressure plate. This flywheel and clutch combination was found on most pickup trucks and was optional on the passenger cars (ie taxis and police cars).

Getting the RIGHT combination of parts is important because you need the larger diameter throw out bearing & hub to match up to your 39 trans input shaft. Regular 49-53 Ford cars used the smaller 9.5" clutch and smaller throw out bearing. If you try to use the 1939 type throw out bearing on a 9.5" pressure plate, you will hear and see the results in no time (screeching and metal dust everywhere!)

[19Fordy]

Mr. Mac VP,
Thanks very much for that very helpful info. It's that kind of tech that makes the conversion mentally easier as it is complete. So, I used method number 1 that you mentioned, but I used the stock 1940 transmission. Does that mean that I probably used the stock 1940 Ford throwout bearing. (There was no squealling or metal dust after installation.) I can't remember as it was a long time ago. Thanks, JIM

[Mac VP]

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19Fordy.....your setup is fine. The 39 trans had the same input shaft/front retainer/throw out bearing as the 40-48 sideloaders.

As a special distinction on the 49-50 Merc pressure plates: these were 10" diameter but had the release fingers set in the larger opening for use with any 32-48 type throw out bearing. It's the 1951-53 Merc B&B clutches that can NOT be used in this application. They are also 10" B&B but the release fingers are spaced closer to the center....for use with the smaller thow out bearing. This is not an easy thing to see buy just glancing at the fingers. The rest of the B&B pressure plate looks just the same as the 49-50 version, so beware of which one you have.

In your case, if you've heard no noise and seen no metal dust, I'm sure you are running the correct 49-50 Merc version.

Also, for those who are considering using a 10" flywheel from a 42-48 motor, this will also NOT work in a 49-53 motor. The starter ring gear is aligned differently and the bendix is likely to malfunction. Stay with the 49-53 flywheel in the 49-53 motors, even if you have to have your flywheel redrilled for the clutch you intend to use.

[rotorwrench]

Where it sometimes gets sticky on the Mercury conversions is with the 1951 Merc. The early ones probably up into very early 51, perhaps February 51 or there abouts, used the same set up as the 49 & 50 Mercs. The B&B pressure plates used for these were either model # 0998 or # 1310. These numbers are stamped into the back cover around the circumference of the opening adjacent to the throw out fingers. When I look for a core pressure plate I look for these numbers. These pressure plates only have 6 of the possible 9 springs from the OEM. Fort Wayne clutch confirmed this for me when I had them do my first one. This allows for lower pedal pressure and smooth operation.

Like Mac mentioned the 10 inch set up has to have the 8BA style flywheel even though the 10 inch Long type pressure plate is the same as the ones used on the earlier Ford 10 inch installations. A persons only option if they can't find an 8BA one with the proper pattern is to redrill one to the pattern you want such as 9 inch Long type or 10 inch Long type. The 8CM Merc and 8BA 10 inch Long type flywheels are getting harder to find as time goes by.

Kerby

[Zeke...PA]

On my 37 top loader I used the flywheel that came with the 8BA and had it redrilled for my 9" clutch/pressure plate that was in the 37. Zeke

[52merc]

i had my 49merc redrilled to take 8ba pressure plate out of pickup

[Mac VP]

Rredrilling the flywheel seems to be such an easy choice, but for some reason it has become harder these days to find a machine shop that can perform this job.

Another point to make when doing all the clutch work...get your flywheel and pressure plate balanced if you can. It makes quite a difference.

[52merc]

mac it was a matter of not being able to find the merc pressure plate down here im lucky i have a man who can do all of this stuff

[Barn Junk]

I think the 8RT 11" truck flywheel, pressure plate and disk work fine as long as you use the "48" or "78" trans case. Of course some may find that their left leg gets bigger than their right over time. ha

[fourtydlx]

Can you use a 11' flywheel, redrilled for 10' c/p truck bell,adap. for t5 trans.?

[rotorwrench]

The 8BA family of flywheels are basically the same with the exception of pressure plate hole paterns. The 11 incher is a good candidate for re-drill since the 11" Long pattern is way out at the edge of the wheel and there is plenty of meat inboard for any of the smaller clutches.

Kerby

[Walt Dupont--Me.]

Originally Posted by Barn Junk

I think the 8RT 11" truck flywheel, pressure plate and disk work fine as long as you use the "48" or "78" trans case. Of course some may find that their left leg gets bigger than their right over time. ha

I've had alot of 11in. flywheels redrilled for 9 or 10in. pressure plates.BUT, it ithe same old story, don't use an 8BA wheel on a 59AB engine. you will have starter trouble. Walt

[Russ/40]

Originally Posted by Walt Dupont--Me.

I've had alot of 11in. flywheels redrilled for 9 or 10in. pressure plates.BUT, it ithe same old story, don't use an 8BA wheel on a 59AB engine. you will have starter trouble. Walt

Walt, I had a post awhile ago on the 8BA flywheel to 59AB engine and the overall consensus was as you state. Today I was curious enough to make a few measurements. On the stock 59AB I just pulled out of my '40, as well as the 41 build I have on the stand with the merc crank and 8BA style flywheel. The setback from the starter mounting flange to the ring gear face was measured in both. The 59AB was 1.169" and the 41 with 8BA flywheel was 1.144". A measly .025" difference. It seems highly unlikely to have any starter engagement problems. It was so long ago, I do not recall what the flywheel came off of, but it is clearly an 8BA type. Perhaps this is why there are differences of opinions on this subject, or different later flywheels account for differences.

[B_man_Al]

I am also adapting an 8BA (1953 ford car) engine with a 9.5” clutch to a 39 style transmission. I have read the various posts about this combination not working because of the pressure plate fingers not matching the thow out bearing face. Mine seems to be OK.

The diameter of the circle made by the fingers is about 2.75” at the center of the contacts, with the finger to finger spacing being about 2.375. The face of the large throw out bearing has a diameter of 2.125” at the inside and 3.25” at the outside, which works out to be about 2.7” at the center of the throw out bearing face, and a good match to the fingers.

I had the pressure plate reconditioned and a new 9.5” disk made with the larger center hub. I did not measure the fingers before it was rebuilt so is it possible they shortened them during the rebuild? They are about 2.25 “ long now, center of contact to center of pivot. I have not put it all together yet so I don’t know if it will work, but it seems to align with the bearing OK.

Does anyone have the required diameters and lengths to make this combination work?

Thanks Al

[Walt Dupont--Me.]

If you useing a 39 trans you should have the 8BA wheel drill for the 35-41 9in. pressure plate, that will take the early thro out bearing. Walt

[Mac VP]

The fingers of the pressure plate extend in toward the center...beyond the contact surface where they touch the throw out bearing. I've seen enough trannies with damaged front bearing retainers to know that the wrong pressure plate can and does cause this problem. I'll try to post a pic of a typical damaged retainer if I can put my hands on one that didnt get tossed into the scrap barrel.

[George/Maine]

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