My Ford is bone stock and after new motor mounts, clutch, pressure plate, bearing and front u-joint replacement it still vibrates when letting the clutch out. I'm sure there is a list of things to check out, that's what I'm hoping to find here. I've heard this is normal and have also read about and have seen an after market damper /stabilizer kit for 49/51 Fords but no luck in finding anything for 42/48 cars. Looking to find out what was actually done back in the day as a normal fix. And of course where do I look next. Any help would be sincerely appreciated.
I've never had a stock one, but aren't there steady rods or something similar on either side of the transmission to keep the motor from shaking when you let the clutch out ? I sort of remember that Hurst sold little adjusters to go under the Ford bisquit motor mounts to take the place of those rods when you did an engine swap. Not 100% sure, but someone else will know. Don
Vibration or chatter? Does it do it at all rpms? Likely your clutch/flywheel is out of balance if so. "New" pressure plates are total junk for the most part and will chatter. I had to put an old one back in my truck, works great.
Flywheel was machined. Pilot bearing replaced as well. Only chatters when starting out and a bit more in reverse. Once rolling no chatter at all.
What condition is your trans mount in? The 46-48 fords and mercs has a new design one piece trans mount that eliminated the need for the earlier steady rods. Matt
That new Trans mount is rubber bonded between two pieces of metal, shaped to prevent fore&aft motion. If old it has failed, if new it is a somewhat dodgy import. Pressure plate is another suspect...as noted, new ones are frequently pretty bad and are often delivered with the fingers at different heights. As you have already noticed, probably, checking out this stuff is about the most labor intensive thing you can do on a '48 Ford. What I would do to try to keep things happy: I'd focus on mount first as there are simple cures. First, add a pair of Hurst anti-chatter thingies. Your local speedshop is out of them, I happen to know, but they are very simple pieces that I think anyone could fabricate...you can find pics on the Hamb and just copy. The common old-days aftermarket chatter cure is also fabricatable...someone on here or on Fordbarn has posted full dimensions, though you could easily just make one as none of the dimensions are actually critical. The existence of this device shows that mount failure or flex has always been common and no one liked the proper solution even back then. Five bucks at JC Whitney, but they are out of stock too... This piece is made from some plain flat steel strip, maybe an inch or so wide. All you need is a vise, a drill, and some screaming and cursing. A look at the bottom of the trans will give you sufficient ideas on dimensions. Bend first piece into a V with a slightly flat bottom. Put ends of V into vise, bend and twist til they point up and can be drilled and bolted to the two lower trans to engine bolt. Drill the flat bottom for a hefty piece of allthread. From distant memory this part is roughly an equilateral unit based on the span between those bolts. Bend another chunk of steel into an S hook. One end hooks into a hole in the X of the crossmember, the other is drilled and hooked to the allthread coming aft from your V. Here's a CAD drawing: >---~ Not to scale... Bolt V to engine, hook S into Xmember, tighten allthread and double nuts in between. That should take about 1% of the sweat and blood required to R&R trans in one of these things! If it's the pressure plate...get a rebuilt, not new one from Joblot or someone and schedule a long, bloody weekend or learn to say "That's nothing, all them old Fords did that."
In 42 the new rubber transmission support replaced the chatter bars. So check it out its probably old an oily and detoriated. If you mix and match old ford part's you can get a Truck disc, and some of those does not have the Marcel spring. Causing an "agressive" clutch http://www.btc-bci.com/~billben/clutch.htm EDIT :Bruce beat me to it ;-)
Hah! Here's how to replicate the aftermarket gizmo...they somehow managed better illustrations than mine: http://www.flatheadv8.org/chatter.htm And a pic of the HIGHLY COMPLEX Hurst Blivet: http://www.jalopyjournal.com/forum/showthread.php?t=621864&highlight=anti+chatter+hurst For that, if you lack a proper CNC toolroom you could stick a piece of Home Depot strap in a door crack and bend it...
The way we did it back in the day was to get some rod and thread it...,there is already a hole in the flange on either side of the trans, and on either side of the front cross member...,just thread the ends and pop it in there with some washers Posted using the Full Custom H.A.M.B. App!
THANK YOU for the great feedback. Will look @ trans mounts as I'm sure they are original and making up the gizmo is very doable. The mixing truck clutch leaves me wondering as the place i got is a very reliable vintage car parts shop. So right now, I'm pretty sure the right parts were installed. But will keep an open mind. I have some work to do, but now I'm have a direction, thanks again!
You probably don't have any anti-chatter rods from the bellhousing to the frame and the tranny mount is probably wore out and grease soaked,it don't hurt to put in new motor mounts either the rubber biskets get slotted out after time also
On the front mounts...some repros are very soft, which surely can't help here! Proper ones are pretty stiff, almost into Hockey puck territory. I've heard that Drake makes the best currently available ones but I have not seen them in person.
I think ShotRod has the answer. I had the same problem on a '34 Ford pickup and it was missing the steady rods that attach to the bell housing at the 3 o'clock and 9 o'clock positions (when viewing from the transmission looking forward) and attaching to mounting holes on the X-Member's of the frame adjacent to the trans. sides. These prevent the engine/trans. assembly from moving forward as the clutch is being engaged. When the rear wheels begin driving, at clutch engagement, the rear axle, through the torque tube, pushes the eng./trans. assy. forward slightly and changes the relationship of the clutch linkage to the throwout bearing release arm, which is like popping the clutch. The rear spring tries to pull the axle and torque tube back into position and the effect is as depressing the clutch and this sets up the oscillation that stops once the vehicle is moving and everything settles into position. Bad motor mounts, and or transmission mounts exacerbates the problem.
Here's one more possibility. Is the clutch disc made of a single piece stamped steel disc that the friction is riveted to, or is it a multiple segment fan arrangement with the friction riveted to? Dampening springs in the center of the disc around the hub with splines for the trans input shaft? If the clutch disc is of the marcel type, being made of multiple segments, heat damage to the marcel spring load in the segments, and the disc being flattened, can cause a similar takeoff shudder. Clutch facing material characteristics can also inhibit or enhance the same depending on choice of facing. FMSI standards on facings. Just food for thought. My bet is on Bruce having nailed it already.
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