Projects Hurst SBC saddle mount: transmission issues?

My dad and I are building a deuce roadster and installing a '62 283 SBC and 700R4. I'm planning to use a Hurst saddle mount for the front on biscuit style mounts and the mount at the rear of the transmission. My dad feels the transmission will crack near the bell housing. This is mild 283 SBC. It's been bored out to 292, 9-1 compression and a z28 style camshaft with dual 4's. So it's not a crazy high performance engine. I'm building a car for the street.

So what say you guys? Am I making a mistake? Who's running a setup like this?

 

I guess there is the "potential" for an aluminum bell housing to crack from the long run between the front mount and the rear mount, but IMO, it is a very slim chance. I am taking that risk on my rpu engine, 350 with a Hurst style front mount and a TH350 trans mount. I have never known anyone to have one crack.

Don

 

I wouldn't do it. But lots of guys have....

Make sure to use a good quality transmission mount, since it will be holding quite a bit more weight than the original one was designed for.

 

I'd be inclined to run a mid plate with a saddle mount like that. I think that's too long of a span from the front motor mount to the trans mount. That's a ton of stress on the bell housing. It may hold up but it may not. I'd rather build something too strong. That's my $0.02.

 

What to mean "good quality"? As in better rubber?

Mathematically speaking, there's approximately 6-8" between the front of the motor and the mid engine mounts(I think). So is there really THAT much weight on the rear mount now?

 

A few years ago, I built a Hammered `29 Sedan on Deuce rails for a customer. It has an early 283 with Tri Power and a Turbo 350. The day after it was finished, we got in and drove 750 miles to Bonneville in it. Never missed a beat. I have had the car back in the shop a couple of times for a few changes/upgrades, and there is no indication of any issues in the bellhousing area. Make sure you have all the bolts in all the holes, check the dowel pins, torque everything and put a flywheel/flexplate shield on the bottom (and not a plastic one, either.) Drive it and check things periodically. It really isn`t that terrible a combination......

 

Do people really not put all the bolts I their transmissions? Isn't the flywheel cover made of lightweight tin? How would it help?

 

Have you ever picked up a sledge hammer by the end of the handle, then picked it up in the middle of the handle ?
The mid mounts are in the middle of the weight of an engine so yes there's a big difference.

 

I figure Hurst sold like 10 zillion of those mounts, and not all of them went onto cars with cast iron bell housings, so I am willing to go with the odds. Like I have always said, there is the real world and the perfect world, sometimes things that should not work just do.

Don

 

The flywheel shield isn`t really related to your question, but I have heard of junk being swept up into the bellhousing area and causing problems with the starter and flexplate. Just another thing to do that takes potential problems out of play. As for the hammer analogy, well that is somewhat correct. Bear in mind that the Chevrolet small block mounts are not exactly in the middle, either. It is your call. I can only tell you what I have found from experience. Others may have had a different result.

 

Those Made in Korea rubber oem style trans mounts start out pretty "soggy" feeling even when new, and I doubt that U.S. made mounts exist anymore.
I would reccomend the Energy Suspension brand urethane stock replacements, but keep in mind they offer two different heighth mounts, about 5/8" difference.
Order the black ones, unless you dig the bright red ones.

 

I have seen cracked bell housings before on TH350 and TH400 trans. not a lot but I have seen and replaced them. I recently changed a trans on a OT Isuzu Cab over truck with a Chev gas engine and an automatic trans because bell was cracked. It had mid mount motor mounts

 

So basically what you're saying is even mid mount sbc's can crack? And maybe they have flaws from the manufacturing process?

 

The side mounts on a small block are not real far back, so the load on the trans mount is only about 50 lbs more with the saddle mount.

 

I've had this combination in my roadster (350 SBC/400TH) since '87, with no issues in over 30K miles. He said with fingers crossed.

 

I split a T400 across the bellhousing and into the shift lever hole, side-mounts and trans mount.
Heavy, hard leaving car, BB, big power.
I have also seen tons of cars with missing bellhousing bolts, thats just asking for it. Keep an eye out for wallowed out dowel pin holes too.
Also seen tons of mild street rod type vehicles go for decades with a trans mount and a hurst front mount. Personally, I wouldn't lose any sleep over what you are proposing.

 

Anyone used the saddle mount and trans mount and cracked the tranny? Falcon George has broke a bell housing with mid mounts...seems maybe it can happen either way

 

On the 700R4, the trans mount is even father back than on a TH350, roughly 4 inches; keep that in mind as there will be even more stress involved. The roundy round racers use a mid mount that bolts to the trans bell-housing bolts; one on each side. Pretty cheap on E-Bay. I've known guys who mounted their engine at the front, used a TH350/TH400 trans mount/rear cross-member, and never had any problems. I've also heard of guys breaking TH350 bell-housings however. My BBC, 56, Model 150, Utility Sedan, bracket car, had an aluminum Powerglide in it. The Glide came from an early Chevy II/Nova, and was an air cooled one with the 4 large holes in the bell-housing. The engine was mounted with a Hurst saddle mount, and the trans with a rear cross-member; I never had any problem, probably because the saddle mount kept the torque over in check. I'd look into those roundy-round racers mid mounts (E-Bay item number 390989759499 is an example, they come painted and anodized gold), and mount things at 3 points; front of engine, bell-housing, rear cross-member, or go with side engine mounts and the rear cross-member. I am Butch/56sedandelivery.

 

I actually thought it was a manual trans didnt read close enough. When Don said "aluminum bellhousing" I saw the std. chevy aluminum manual trans bell in my head, thats what I was thinking of when I said I'd seen lots of cars with hurst front mounts and a trans mount last decades.
The 7ooR4 is kind of a wild card, can I retract my endorsement?

 

I've seen at least one cracked bell housing from using a hurst front mount, but I have seen a few guys log a bunch of miles without issues

You have to remember those old hurst mounts were more of an engine swap deal to " bolt" an ohv in where a flathead once was , the span where the trans mounted was a bit shorter than later transmissions.. Isn't the 700 mount further back yet like 4" from a glide?

 

NO! You can't!!

 

thirtytwo, was the cracked bell you saw an automatic, or a manual trans bolted to the stock chevy manual aluminum bellhousing?
The T-400 I split was on some nasty ol' falcongeorge streetracer type stuff, it was pretty extreme compared to most of your typical HAMB type stuff.

 

I'm currently setting up a 327/Muncie combo in my 32 Coupe with a Hurst mount. I'm planning to use as a factory aluminum bellhousing. I'm really curious to hear if anyone has seen one of these crack when used with a Hurst.

 

I don't think the issue is with a manual tranny...it's the length and weight of an automatic that potentially causes problems.

 

It was a turbo 350 in a old hotrod

 

thanks thirtytwo. My gut feeling is that a four speed bolted to the back of a chevy bellhousing is far less prone to cracking than an automatic bellhousing.

 

I have seen hundreds of cars with front engine mounts, and no mid-mounts.

I have seen dozens of broken bell housings.

I have never seen a car with a front engine mount, no mid-mounts, and a broken bell housing.

I do not believe that there is a not already damaged GM transmission that is so fragile that cannot tolerate the engine mounts being moved 7" forward.

 

I would think all the ribs would add quite a bit of structure. Vs. the auto. But for piece of mind .. An old Lakewood bellhousing would probably be my choice

May only be 7" but it's a matter of weight distribution that side mount is almost in the center of the motor , now you just move it to the end... Pretty big stress differance on that bellhousing ..

 

I've seen several T350's and Hurst style mounts break the bell housing...but they were all drag racing at the time.
My opinion is the problem is a combo of the distance between the mounts and the torque of a hard launch, both combining to overstress the bellhousing.
I don't think its just a weight distribution issue.

 

I was not sure so I added some mid mounts on the bell housing. I will be pulling my body in the next week and will take a picture.