T5z 5th gear change

fxbill · #1 (**permalink**) 07-12-2003, 02:35 AM

Hi,
I have a T5z tranny with a .63 5th gear and it's killing me! I know there was a .80 offered in the same trans. ..Can this be installed in my present trans? If so.. anyone know about how much it costs to do it?.. and if there are any reputable places out there that can?
I have a local shop here in L.A. that's offered to do it for $300 if I take them the trans, but I'm not sure as to their reputation. I'd rather talk with others who have possibly already gone this route...
Thanks,
Bill

aumoore · #2 (**permalink**) 07-12-2003, 10:07 AM

Bill
You say you have a T-5Z behind a 351 stroked to 427 and it puts out 529hp and 470ft.lbs of torque? If so do not waste you time and money trying to change the 5th gear unless you just baby the car all the time. T-5's are ok behind a mild 302 but they will not hold up long behind a motor like yours. Put you money into the bank and save for a Tremec TKO and a good bellhousing.

My T-5Z lasted a few track events before third gear gave up the ghost. Third gear is a common problem with the T-5.

Or you could just order a Tremec with the 5th gear you want and sell the t-5 to a guy with less HP and Torque.

Trust me on this as I just put in a Tremec 3550 after my 267 rwhp/285rwttq 302 busted my T5-Z and I do not drag race. I was running on a small road course and it went on my second lap of the day.

fxbill · #3 (**permalink**) 07-12-2003, 10:33 AM

Thank you Aumoore. My 351 is stroked to 408 and the HP and torque figures were on an engine dyno when the motor was built, but then I'm sure you knew that....I have yet to dyno it at the rear wheels and to be honest at this point I'm not too concerned with what it has there...it's more than I'll ever need....or be able to use for that matter! ( obviously it's a lot less and probably less than I imagine)
Very little of my driving is is that hard ....the car is a daily driver. Because of the light weight of the car and the lack of solid traction I thought the tranny would hold up for a while. I'm sorry to hear that they go out that easily.

wilf leek · #4 (**permalink**) 07-12-2003, 04:19 PM

fxbill - England is littered with broken T5's which were fitted behind 351's and larger engines.

Don't fall for the "it's a light car so the rear wheels will break traction before the gearbox breaks" line. Just think about full throttle in 3rd or 4th - gearbox sees ALL of the engine torque without the rears lighting up.

Tremec TKOII has the 0.8 ish 5th gear you want.

HTH

aumoore · #5 (**permalink**) 07-13-2003, 09:50 AM

FXbill
I fell for that light car and light traction line too and I found out that thrid gear is pretty week. I was laying into the throttle and not powershifting when third gear went "KAPOW!" about 1 second after I had let out the clutch. Torque will kill a t-5 and you have a bunch of torque.

If you were running a stock 5.O the T5Z is a great tranny but if you plan to mash that torque monster of yours just save you pennies and time for when you have to replace it.

Buzz · #6 (**permalink**) 07-13-2003, 10:40 AM

If you are already running a T5, this is the ultimate upgrade. For about $1950, you can buy a T5 case filled with bulletproof G- Force gears and internals. Famous for their incredibly strong racing transmissions, G-Force will also sell you a rebuild kit or they will rebuild your existing transmission to their specs. Various 5th gear ratios and a choice of synchronized or dog-ring engagement. Check out the site and give them a call- they seem like nice folks to deal with.
http://www.g-forcetransmissions.com/tran_gt-5.asp

fxbill · #7 (**permalink**) 07-13-2003, 01:31 PM

Thank you guys.....I'm convinced....and I appreciate your honest input.....I'll wait for the Tremec.
I looked at the GForce site and all they list for 5th gear ratios is a .59 ...just the opposite of what I'm looking for. I will, however, call them this week and do some price checking....I've got another '85 T5 laying around that would be a great candidate for the upgrade if it's affordable.