Gear Change

[rich95]

Hey All,
Recently, I went to a Corvette shop here in Northern VA and asked about changing my 95 Auto from a 2.59 to a 3.54 rear axle. In the discussion, I asked him about calibrating the speedometer and he said there is not gear to change in the transmission. He said there is an electronic device which has to be hard wired into the transmission wiring harness. Has anyone out there who has changed rear axles on there 95 used this device. I have some reservation about cutting into a wiring harness. Any help you can provide would be much apprieciated.
rich95

 

[vader86]

Yeah youll need the PCM programmed for the gear change. A hypertech PP unit will do it, or have someone program the PCM for you.

 

[wookiebear]

Rich,
You can pick up a Hypertech Power Programer used on E-Bay for $100 to $125 bucks, this device is very easy to use and will allow you to adjust the speedo to the new gear ratio. It will also allow you to change your shift points, shift firmness and the electric fans for the 160 degree stat. Look for one that is designed for the LT 1 Corvette for 95.
I changed my rear from the 3:07 to the 3:73 and I am very happy with the accelleration out of the hole.
Good Luck!

Wookiebear

 

[rich95]

Thanks vader86 and wookiebear, sounds like the Hypertech unit is what I need. That is a whole lot better than cutting the wiring harness. I guess I need to find another shop to do my swap. If the guys didn't even know that the PCM could be re-programmed, I not sure I want them turn any wrenches on my 95!
Thanks again
rich95

 

[vettn94]

Do yourself a favor and find another shop.
Like Wookiebear said best way, other than using LT1 Edit, is with the Hypertech unit , I got mine used for $150. Even if you bought a new one at $300 you're better off than having the PCM programmed by someone else.
Intsead of having someone install gears in your current rear end have you thought about just buying a complete rear end ? You could swap it out yourself or if you still had a shop install it would be less labor. That way you also won't have to worry about the shop screwing up your gear install. Installing the rear end as a complete unit is fairly straightforward.
I paid around $1200 outright (no core) for a Dana 36 w/ 3.54 gear. I think Zip products sells them for $850-$900 price range but you have to send in your core. something to think about.

BTW when I switched to the 3.54 from 2.59 gear, my times at the track went from 13.82@101mph to consistent 13.20's & 30's@105.5/105.9mph

good luck

 

[rich95]

Vettn94,
Thanks for the input. Yes, swapping the entire carrier is the way I would like to go. This guy at the Corvette shop called Eckler's and they told him they only sold the ring and pinion. I don't want to do a rebuild, I just want to swap the entire carrier, I'll check out Zip products. I have been looking on Ebay for a Hypertech. I did notice they have serveral different units, at Hypertech, a Hypertech Plus, and a Hypertech III. Which should I buy?
Rich95

 

[vettn94]

get the plus or III model.

 

[LUDS96]

Power Programer

there is now 3.54 gears in the power Programer. I used the 3.45 and changed my tire size! Using a GPS to verify the settings worked Great.

 

[Doutdoor]

Just my 2 cents worth, but here it is. I plan to change out to the 3:54 gears in my 92 LT1. I'm going to remove the entire unit myself & then reinstall it (with help from my brother-in-law whose a mechanic). I'm going to take the unit down to Randy's Ring & Pinion in Everett, WA & have them do a complete rebuild. Total cost is about $750.00. It's cheaper than buying a complete pumpkin assembly, having to do the $400 core charge and waiting for your money to be returned, plus you know exactly what your getting. I plan to talk to Randy's about the setup to minimize the gear noise as much as possible too.

With my 92, I have to change the speedo gears in the rear tail section of the transmission, but I don't anticipate it will be that difficult. From a post I did back on 2/28/03 of this year and the great input I received back from members here, I was able to obtain all of the information I needed to make the decision and do the job. This weekend the unit comes down & it goes into the shop. Good luck with yours.

Dave :cool