Engine cross member

[Coupefreak]

Howdy, I'm brand new to the T-bucket scene, but I'm eager to learn:surprised:

I was wondering........do I need a engine cross member?
I have been looking around at different buckets, and notice some have them, and some don't

so whats the divergent opinion here?

Thanks

Vance

 

[tfeverfred]

Welcome to the forum. :welcome:

It's going to depend on what engine you use and the design of the frame. My engine/frame combo uses a cross member. My engine is a SBC with the oil sump in the rear. An engine with the sump in front, will most likely have the engine mounts on the frame and probably won't have a cross member. It seems to me that my crossmember adds to the rigidness of the frame by tying it together. But the other way is probably just as strong.

 

[PaulR]

Vance,

Mine, like TFeverFred's will be a SBC with the oil pump in the rear. However, it will not have an engine crossmember. I don't think it will be a strength issue since I don't plan on taking it out to the track a lot. That's not to say I won't be doing some rapid acceleration comparisons with other vehicles....hehehe. I think if I were going to really be hard on it, have a lot of hp in it, I'd would have gone with the crossmember. My .02 worth.

PaulR

 

[Coupefreak]

Thanks for the replies, i appreciate the info.
I do not have a cross member in my Coupe, its a SBC with a 'glide tranny.
every once in a while I hafta "air it out" so far no problems.

Vance

 

[Mike]

With a crossmember, the frame is strengthened with the tubing used.

Without a crossmember, the engine block becomes part of the frame, as it is the actual crossmember.

In a street application, it's likely a toss-up. In most situations, you're never going to get the car to actually get hold of the ground anyway.

Put a good tire on the car, with a suspension that will plant the the tires hard, take the car to a prepped racetrack and you've suddenly got an entirely different situation on your hands. In that scenario, I don't want the block to be a stressed part of the frame. At that point, I would want both front and rear motor plates, so they are the stressed members and not the block.

Horses for courses...

 

[Coupefreak]

Makes sense.

I will probably use a mild small block.
some food for thought.

Thanks for the replies, I do appreciate it

Vance

 

[digger]

mine dosnt have an engine crossmember and the engine/gearbox is mounted with urethane bushes, i agree with the previous replies about depending on the engine, I have driven miine hard on the track and drive it a lot on the street, around 5,000 miles in three years and hav'nt had any problems with it so far.

 

[tfeverfred]

Food for thought, if you use a crossmember, DO NOT WELD IT IN. If you do and ever have to relace the oil pan, you will need to lift the engine (if it's a SBC) to get the pan off.

 

[digger]

Food for thought, if you use a crossmember, DO NOT WELD IT IN. If you do and ever have to relace the oil pan, you will need to lift the engine (if it's a SBC) to get the pan off.

Yes this IS a good idea, also make the gearbox crossmember bolt in as well, that way if you need to take the box out you dont have to take the engine out....... unlike mine. its great to think about it after the chassis is painted !!

Although saying that I can get the engine/box out in about 20 mins and have done twice!!!

 

[Leon renaud]

the use of a frame crossmember under the engine and carrying the motor mounts prevents the motor from acting as a wedge and trying to spread the frame rails apart.This is why most of the early car motor mounts used a system where the engines weight was transfered in a downword load on the frame rails

 

[Lowrollerchevy]

^^^^ very true

if the rubber / poly mount is closer to the block youll flex the frame more

if teh bracket comes far off the block and the ruber / poly mount is near the frame, less flex

if the rubber / poly sits ON the frame, least possible flex of the frame rails

 

[Youngster]

The only 2 times I've used one was with a BBC and a 390 Ford. For most small blocks, they aren't really needed.