Aftermarket 6 speed

[Tiredmechanic23]

may check w/ Circle D, Sonnax, Century trans, Jasper, gwatney perf, or mad dog trans for some info & see what works best for your budget & such.
(the last 2 are mentioned on camaro & vette forums.)

could also buy a rebuild kit from above & do yourself or find a diff shop to do it.
pirate4x4 & a camaro forum have good posts on rebuilding them.

I looked over all of them. Gwatney seems reasonable and are one of the few with the right trans available. Ill call them Monday and see what the reccomend for my plans. If need be ill get ahold of blackbear for a full tune as well.

 

[Mechanic421]

Well, like they say, no one is perfect but I am curious about that problem. I never used them for any diesel parts/assemblies. Was it on big tractor rigs and was it on Detroit's?

So I believe it was a 3.9 Isuzu mechanical injection we sent to them. We sent them a complete running engine less accessories . It ran ok but would misfire and smoke pretty good on cold start then clear up for the rest of the day. I believe it had a bad injector . It did always run warm on the highway. So we get it back install fires right up like they ran it. But same big black cloud of smoke and misfire till it clears all the extra fuel (aka bad injector) go figure. And still ran warm on the highway. So it did have a totally new cooling system. So the warm thing could be any thing I know brakes,transmission,overloaded most all of these were checked out. So back to jasper again time two. I reinstall engine in truck with no charge at all . Mine you we sent engine complete and running. They were to rebuild everything injectors,injection pump ,turbo and engine. All it probably needed was one injector. Boss man would not ever let me even find the bad one.

 

[Mechanic421]

I looked over all of them. Gwatney seems reasonable and are one of the few with the right trans available. Ill call them Monday and see what the reccomend for my plans. If need be ill get ahold of blackbear for a full tune as well.

All I know is circle d would not hurt to call also.

 

[swathdiver]

Apply piston cracked and ive only got 1st and 2nd.



As far as a self build I may go that route.

Sonnax makes great parts for these, so give them a look for consideration.

 

[tom3]

Might keep in mind that for any warranty to apply the transmission probably has to be installed by a professional shop, maybe one that is approved by the rebuilder.

 

[iamdub]

I believe it was @donjetman that recently posted a video of a boosted CTS-Z running 10s or thereabouts on a stock 6L80E. Just had good tuning.

*EDIT*

Correction: It was a 6L90E, world's quickest and fastest with 8.59 @ 163.97. Build it to 6L90E specs and get a GOOD TUNE. Stock tune kills them.

https://www.tahoeyukonforum.com/threads/worlds-quickest-and-fastest-6l90e-transmission.115778/

 

[Tiredmechanic23]

Might keep in mind that for any warranty to apply the transmission probably has to be installed by a professional shop, maybe one that is approved by the rebuilder.

I can have it signed off as being done by a pro shop... I am a tech by trade just normally deal with diesels at work and do auto on the side. I know many people who I can just ask to make up a work order/receipt and have it. But either way if I self build then I am the warranty. Never ventured into trans rebuilds only engine builds. But you cant learn without doing so I may very possibly go that route depending on what I hear from gwatney.

Sonnax makes great parts for these, so give them a look for consideration.

Gwatney uses sonnax parts. They list what parts they use as well when you select the trans build level. If I self build it will be sonnax or CDT parts I use for this reason as both have good parts.

I believe it was @donjetman that recently posted a video of a boosted CTS-Z running 10s or thereabouts on a stock 6L80E. Just had good tuning.

*EDIT*

Correction: It was a 6L90E, world's quickest and fastest with 8.59 @ 163.97. Build it to 6L90E specs and get a GOOD TUNE. Stock tune kills them.

https://www.tahoeyukonforum.com/threads/worlds-quickest-and-fastest-6l90e-transmission.115778/

6l90 is a physically larger transmission as well. Not by a huge amount but it does matter in their strength. The cost of converting to the 90 as well is not worth it to me at the moment. I rather spend the 2500-4k on a build kit/rebuilt trans.