Upgrade transmission or what can I do?

[Jimmi The Kid]

First off all, people allways talks about the stock transmission are too weak and can not support 200hp. Can someone please tell me what exatly the problem is? and mayby upload some pics of the broken parts.

The reson why, is I newer have any problem with my transmission, but my engine was stock and now I'm building a new 200hp+ race engine.

I have thought swapping an other transmission, like the BMW M3, Mazda MX5/Miata or even a Ford Sierra 4 or 5 speed.
Who have tryed one of these swaps?

I know some tranny's break because of the 2 axels move away from each other, and then the bearings and transmissioncase breake. This problem will be eliminated when fitting a straight cut gear set, but I don´t know who make those for AE86. Straight cut, I mean like the reverse gear, not as the TRD gear set.

At last, which gearkits are available for AE86???

[4000GT]

The stock unit should support 200HP. As long as its in decent shape.

[Project D]

Quaife make straight cut gear set
but that kind of gearbox is realy noisy (not realy an issue on race car anywhay)
but on N2, many guys use OEM Gearbox with different gearset (like TRD gearset) without any problem.
maybe they are refurbished sooner than a "street car" but more because of the aggressive use, than the Horse power passing thought it

[jondee86]

Abuse kills gearboxes, not horsepower. Dumping the clutch, driving
over kerbs with power on, anything that puts sudden and high torque
loads on the gears. Helical/spur gears have only a few teeth in contact,
and the teeth can only sustain a certain load before they break off.

Sudden, high impact loads can break them. Repeated high torque loads
above design, will lead to fatigue cracking and breakage. Continuous
high torque loading with high temperatures or poor lubrication will lead
to surface fatigue, cracking, pitting and failure.

As said above, if you use the clutch with some consideration, and avoid
kerb jumping etc., the T50 will handle 200 hp from your high revving,
but relatively low torque engine Plan on servicing the box regularly,
and you should be fine.

Cheers... jondee86

[Eircamae86]

The sierra box swap has been done loads of times in Rally cars & works very well, Fensport used to sell the bell housing.

http://www.fensport.co.uk/Parts/Model_3/Category_3/

If you are interested in going this route, PM me as I think a mate of mine in Ireland has one & the clutch etc sitting round since he sold his car. I was going to buy it but I can only get the sierra cosworth box here Australia with is a different fit.

http://www.ae86irl.com/forum/showthread....a+fensport

There are adaptors around for W series boxes out of the Supras, RX-7 & a few others I cant think of right now.

[Jimmi The Kid]

So its actually the gearset that breaks?

That strange, because Toyota's FWD trannys can handle 7-8 times as much horsepower and 4 times more torque, than its suposed too, even with M/T drag slicks and even shifting @ 9500rpm. Of couse on a drag strip, not a bumpy road :wink:


I know about the Quafe gearset, but some people have trouble with these, they stuck in gears. And its a pretty expensive upgrade.

I thought I have bought a Ford Sierra 4 speed dogbox, but when I got it opened, it was a stock Ford tranny, with a 4AG bellhousing
Also the quaife dog gearset can not support more than 185hp, and only 7000rpm or so.


Who else beside quaife and TRD sells gearsets for our cars? And I don't care about the noise, I think its one of the sweatest sound ind the world such a race transmission.

[Roger]

here is a dogbox for sale

http://www.classiccarsforsale.co.uk/clas...hp/id/1359

[totta Crolla]

Have a look at the Quaife[u:d318775f0c] pro [/u:d318775f0c]Ford type 9 'box as the shafts rotate on needle roller bearings it can stand higher revs than the normal Quaife set.
Expect to change the ring and pinion to something like a 4.8 or ideally a 5.375 to make the most of a close ratio box.
Dogboxes are nice but the dog rings are expensive and need changing at regular intervals.