7AFE Conrods, When Do They Bend or Break?

[PrettyCoolWagon]

A little of topic but interesting for anyone heading down the 7A route.

Link to flywheel issues with 7agte.

http://www.toyotanation.com/forum/13...v-project.html

[Duk]

A little of topic but interesting for anyone heading down the 7A route.

Link to flywheel issues with 7agte.

http://www.toyotanation.com/forum/13...v-project.html

The 7AFE also uses a smaller clutch that the 4AGZE, 215mm VS 224mm. And because of the larger input shaft of the SC AW11's gearbox, the best result I can think of to bring the 7A together withe the SC AWW11 'box as well have a decent clutch for the MR2's great traction, is to have a flywheel custom made to get the job done.

[PrettyCoolWagon]

Duk,
There's no need for a custom flywheel.

The 4wd corolla uses the same diameter flywheel, clutch and pressure plate as your AW11 4AGZE.
(AE101 4AGZE clutch/flywheel is larger in diameter and so doesn't work.)

Use the 6 bolt corolla 4wd flywheel with the 6 bolt 7A crank and get 3 hardened steel dowels drilled and press-fit through the flywheel into the crank. Run ARP flywheel bolts and fit whatever aftermarket heavy duty AW11 4AGZE clutch you like.

This is first hand info.
I have all the engines and clutches listed above (7A, AW11-GZE, AE101-GZE & 4WDrolla) ..and I've test fitted all of them.

http://img.photobucket.com/albums/v3...it-to-jari.jpg

http://img.photobucket.com/albums/v3...e_flywheel.jpg

[oldeskewltoy]

from what I have read it doesn't appear they fail from the shaft bending or breaking. it looks like bolts that join the cap onto the conrod stretch/shear/strip etc at higher rpms. because unlike 4age rods they do not have the bolt and nut holding them through, they just have a bolt from the cap into a tapped rod

Atlantic rods have cap screws that screw directly into the rod...... so I SERIOUSLY doubt the design is at fault....... it might require an ARP fastener, or some other engineering solution to solve...

[Hiro]

Atlantic rods have cap screws that screw directly into the rod...... so I SERIOUSLY doubt the design is at fault....... it might require an ARP fastener, or some other engineering solution to solve...

How often are those engines rebuilt though?

[DX20VT]

I think it is the size of the 7A rod bolts that are an issue, they are reduced in size and the centre and quite skinny,
much less than a 4A rodbolt and way thinner than they look until you actually remove one from the rod.

[Sam_Q]

Also formula Atlantic rods are a machined billet rod, a thread into it is structurally great unlike a thread into cast steel.

[oldcorollas]

atlantic do it to save the weight of a nut.

good bolts into 7A rod shouldn't be a problem unless thread in rod strips (no comment on rest of rod)

[Sam_Q]

atlantic do it to save the weight of a nut.

good bolts into 7A rod shouldn't be a problem unless thread in rod strips (no comment on rest of rod)

you are right, also looking at it I would imagine having the recess for the nut would also put a stress raiser in the base of the rod and therefore require more material thickness to compensate.

I don't like to quote unconfirmed information but apparently the thread stripping out is exactly the problem

[Duk]

Duk,
There's no need for a custom flywheel.

For an affordable option, the 4wd corolla uses the same 224mm flywheel castings and clutch as the 4AGZE, the only difference being 6 bolts instead of 8. Provided you can source one, it's easy enough to use the corolla 4wd flywheel on the 7A crank (cause they're both 6 bolt) and get hardened steel dowels put in, or drill and tap 2 or 3 smaller bolt holes throught the flywheel into the crank and fit some hight tensile bolts.

Cheers, but I had MRP make me a 6 bolt version of their 4AGZE flywheel. The dollars were good and so is the product. It's also quite light and I'll use ARP flywheel bolts for a 4A.

I am keen to know more about the potential conrod bolt issue and if anyone knows if the can be replaced with ARP bolts for the 4A???

[DX20VT]

I am keen to know more about the potential conrod bolt issue and if anyone knows if the can be replaced with ARP bolts for the 4A???

not they cannot as they are a completly different design.

[Duk]

I don't like to quote unconfirmed information but apparently the thread stripping out is exactly the problem

Sounds to me like a stud screwed into the rod would be the go.

[MRMOPARMAN]

for 160rwkw boosted, you'd be throwing in pistons and a rebuild at minimum right?

by the time you prep a set of stock 7a rods (close and hone, new little end bushes, rod bolts, maybe machining the weights and polishing beams, shotpeening etc) it would be cheaper to buy a set of aftermarket rods that are ready to go, with the added bonus of piece of mind they aren't going to break, and futureproofing if you get the power bug.

for me, the answer is obvious.

btw.. the spools will probably need machining and prepping off the shelf anyways.

[Sam_Q]

Spool rods are meant to be very close in their tolerances. I think that if a new part doesn't fit right up then it should be sent back

[Duk]

for 160rwkw boosted, you'd be throwing in pistons and a rebuild at minimum right?

by the time you prep a set of stock 7a rods (close and hone, new little end bushes, rod bolts, maybe machining the weights and polishing beams, shotpeening etc) it would be cheaper to buy a set of aftermarket rods that are ready to go, with the added bonus of piece of mind they aren't going to break, and futureproofing if you get the power bug.

for me, the answer is obvious.

btw.. the spools will probably need machining and prepping off the shelf anyways.

I don't see the need for a built bottom end with only 160rwkw. If the rods stay straight and properly attached to the crank, there is no need.

If the power bug does start to nibble, I'll go a built engine with new rods and forged pistons.
I'll be pushing the little R34 GTR turbo pretty hard to get what I'm after and they use a really small turbine inlet (I'm aiming for the smallest, but still well flowing exhaust system volume from exhaust valve to turbine wheel) which is in line with my intended 'big fat torque curve (for a 1.8)' requirements for this engine. So if I do start chasing big HP, I'd need to at least modify my exhaust manifold so the collector's outlet is bigger to match the usual T25 turbine housing inlet size.