1999 Firehawk transmission question

**gtsleith** · 05-08-2015, 06:04 AM

Hello, I'm new to the LS1 site and happy to be here!
I have a 1999 Firehawk my Dad left me when he passed 3 years ago. It's very well maintained but lately when I'm driving on the highway at a constant speed the RPMs increase, the motor starts to rev and I seem to lose power and start slowing down. I can step on the gas and it eventually corrects but I think the transmission is slipping. Any thoughts? Thanks Gary.

**2002ssslp** · 05-08-2015, 06:10 PM

M6 or A4. Either way your clutch or clutch packs may be the cause. I need more info but lets start with the first question. Do you have three pedals or just two.

**Delcotrans** · 05-08-2015, 06:32 PM

Check the fluid level first , if it's full then sounds like you have burnt 3/4 frictions ! Hate to say it but you are going to need an overhaul ! Common failure if it is a 4L60E !

**pajeff02** · 05-09-2015, 02:20 AM

Welcome to the site!

Pull your transmission dipstick (assuming A4) and smell the fluid to see if it is "burned". Could be a couple of things, but toasted frictions are a distinct possibility. If you cooked the trans, rather than attempting a rebuild there are several companies that offer built 4L60E's. We run a Performabuilt with a 3,200 stall in our car and love it. If you do rebuild the trans, at least invest in a Beast sunshell and a better front pump.

**pajeff02** · 05-09-2015, 02:20 AM

Welcome to the site!

Pull your transmission dipstick (assuming A4) and smell the fluid to see if it is "burned". Could be a couple of things, but toasted frictions are a distinct possibility. If you cooked the trans, rather than attempting a rebuild there are several companies that offer built 4L60E's. We run a Performabuilt with a 3,200 stall in our car and love it. If you do rebuild the trans, at least invest in a Beast sunshell and a better front pump.

**gtsleith** · 05-09-2015, 06:47 AM

Oh yeah this might have helped, it's an automatic transmission. Fluid has been replaced during regularly scheduled maintenance. I do not know what transmission is in the car but I'm assuming the most common seen in the replies is the 4L60E?

Everyone, thank you for the fast responses and making me feel welcome! If I decide to get another transmission are there any places you recommend?

**RONS98TA** · 05-09-2015, 07:27 AM

Welcome to the f-body world. Refer to what pajeff02 said. Performabuilt makes a really nice unit. Also while your at it, get a nice stall. 3200-3600 is a really nice happy medium. It will really "wake up" the car and you really wont notice much of a difference in fuel milage.

**pajeff02** · 05-09-2015, 07:42 AM

We track our car regularly and have had zero issues with the Performabuilt trans.

**gtsleith** · 05-11-2015, 11:00 AM

Thanks everyone for the advice greatly appreciated! So I'm leaning towards getting the transmission rebuilt I would like to keep the car as genuine as I can. I'm getting some estimates and looking into the recommendations of getting the 3200 stall as well. If the rebuild is too expensive I may go with just replacing it so we'll see. I don't know if there are any advantages to a rebuilt verses a replacement.

**pajeff02** · 05-13-2015, 03:18 AM

A rebuild allows for replacement of the weak stock internals with something a bit more robust. Check out this thread to see what all goes in to a rebuild (this is the transmission installed in our car that you will see in the pics): http://www.ls1.com/forums/f8/perform...d-pics-153471/

**gtsleith** · 05-13-2015, 03:42 AM

Ok, wow that's impressive. I think I'll give them a call and see what they can do for me, thanks for the info, great read and pics!!

**pajeff02** · 05-13-2015, 05:12 PM

Glad to assist. Let us know what you end up doing.

**pajeff02** · 05-13-2015, 05:18 PM

Forgot to mention - Performabuilt does not require a core, so I still have our stock transmission. It had zero issues when I pulled it out in 2011 with around 74,000 on the clock. It has been stored in our lower garage ever since. If you need a good transmission, I would gladly sell it for far less than what an aftermarket trans will cost you.

**gtsleith** · 04-15-2016, 07:05 AM

Update, I just got the car back, went with the Performa built street level one after talking with Allen, great guy! I went with a 2200 stall and had the rear end rebuilt while it was all apart. The car has 120K miles on it. Car runs great now. I have about a 2000 mile break in period before I can really see how she performs. Thanks again for all the help it's nice to have her back on the road! I have my core as well I need to get rid of.