Input from those with Built Transmissions

[belize1334]

I'm trying to build my car to be a cleaner-uppper in autocross under "D Street Prepared." The next thing on the list is a rebuilt transmission with synchros that actually work...

Now, strictly speaking I am not allowed ANY modifications to the transmission with the exception of the differentials which I'm free to play with. But, I'm happy to "turn a blind eye" to anything that will make my vehicle last longer so long as it doesn't actually make it faster in any given run. So, for instance, an updated 3/4 fork won't make me any faster but it is less likely to break which means I won't have to buy another transmission. This is my general philosophy... I'll bend the rules so long as the end result makes me more reliable (and thus less expensive in the long run) but not if it can be construed as a "performance benefit" with implications toward my actual speed on the course.

Ok, so what about synchros? Most transmission rebuilds offer double-synchro 2nd as a standard element and then a double-synchro 1st if you want it. This supposedly allows for 10k rpm shifts (applicable to drag racing) as well as promoting the life of the synchro assembly. Well, longer lasting synchros sound GREAT. If my next transmission lasts a decade and the synchros never give out I'll be a happy camper. But what about the "on course performance" of a double ring synchro assembly? If I remain in the 3-7k rpm range, will I "notice" the difference from a double synchro setup? If it makes the shifts faster by 1/10th of a second it could well add up and make the whole run faster. Probably nobody would notice... but I'm trying to be honest here. I'd feel bad if I won something knowing that I had cheated in a way that contributed to my victory...

So, that's all by way of saying... for those with double synchro gearsets, can you tell the difference in "normal" rpm situations? Does it shift smoother and faster or is it just longer lasting with implications in the extreme rpm range?

 

[gtluke]

get an RS trans and rear, it would help a lot in autocross in a stock class.
an evo3 trans would be better, but good luck finding one.
RS transmissions are dirt cheap.

 

[belize1334]

RS is JDM import and not legal. Must be USDM Galant VR4 gearset. It's just a question of what I can and cannot do as far as upgrades and still remain within the spirit of the rule.

 

[Terry Posten]

Have your box rebuilt with EVO III input shaft (stronger) and EVO III 1st, 2nd, 3rd, 4th gears (5th is not necessary). The EVO III gears give you double syncros on 2/3/4 and you can tell the difference in shifting the whole way up and down the rev scale. With the E III gears sets, get the revised 1/2 & 3/4 forks. Much stronger.

The EIII 1st is taller but not by much. The most important thing is it is stronger than even the 1G gear (stock GVR4 gear is the weakest). The 2nd gear is the same but for the cost, you may as well get a new gear if you are going this far. The 3/4 EIII gears are closer together and helps with boost lag between that shift.

As far as the "rules", NOBODY will be able to tell what you have done inside that box. Everything is OEM and there is no part numbers even stamped on the gears at all, they all look the same (except for the 1st gear, it is noticeably thicker).

The only issue you have with the EIII conversion is if you have an early 91 tranny. If you have that model, the intermediate shaft and center diff will need to be upgraded to a late 91 or later set. They changed the tooth angles and they are not compatible. And don't think you can tell by the model number on the case. There is nothing that tells you this info, you just have to have it looked at internally. (sucks big time - cost me quite a bit of money and time when I had mine built)

 

[belize1334]

I understand all the things that I could get away with but that's not what I'm going for. I'm not using an E3 gearset. Strength isn't a huge issue. This is a stock engine / stock turbo setup so we're talking less than 300 ft-lb max...

I just want to know if people have FELT the difference in a double-synchro setup while shifting at "normal" rpm levels. It sounds like Terry can feel the difference.