Manual Transmission Swap
09-05-2007, 06:56 PM
#1
Manual Transmission Swap
I'd like to eventually replace the automatic tranny in my 1985 vette with a 5 or a 6 speed. I found a kit that will replace the auto with Keisler Tremec 5-speed manual. However I was also wondering if I could swap in a ZF-6 speed as the 89-91 vettes had this transmission mated to an L-98.
Any input is appreciated
Any input is appreciated
09-05-2007, 09:19 PM
#2
Burning Brakes
Member Since: Sep 2000
Location: NewCastle IN. USA
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welcome to the forum.
yes it can be done (and has been done, try a search on transmissions), the ZF, TKO and richmond kit are probably the easiest to do (compared to others like a T56).
let me try and change your mind though.
any of those swaps will cost you $3000 or more (plus labor) to do on your auto 85. why not just trade up to a 92 or newer vette with a 6spd?
you'll be getting more power (LT1 motor) plus all the updates they did since 1985 (ie: suspension, power windows, wipers ect. lots of little changes that improved the vette).
and you won't bust your knuckes.
even trading to a L98 with factory 6spd (89 to 91) could be less expensive.
but if your set on changing yours, it can be done.
good luck.
RJ
yes it can be done (and has been done, try a search on transmissions), the ZF, TKO and richmond kit are probably the easiest to do (compared to others like a T56).
let me try and change your mind though.
any of those swaps will cost you $3000 or more (plus labor) to do on your auto 85. why not just trade up to a 92 or newer vette with a 6spd?
you'll be getting more power (LT1 motor) plus all the updates they did since 1985 (ie: suspension, power windows, wipers ect. lots of little changes that improved the vette).
and you won't bust your knuckes.
even trading to a L98 with factory 6spd (89 to 91) could be less expensive.
but if your set on changing yours, it can be done.
good luck.
RJ
09-06-2007, 12:54 AM
#3
Race Director
Most of the swaps are manual to manual though. You might try Central Coaster (when he's not busy harrassing the ZR1 guys
) He pretty much wrote the book on the swap. Remember to get any performance though you'll have to change the rear end too. A few years ago, it might have made more sense, but the 6spd cars are getting alot cheaper (just passed on a running, driving, cold AC, 95 6spd for $6000!)
09-06-2007, 01:14 AM
#4
Team Owner
Member Since: May 2002
Location: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
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Both Keisler and ClassicChevy5speed offer Tremec kits for the C4 for about the same price. The ZF6 is definitely a cheaper option, but will take more running around to gather all the parts needed.
09-06-2007, 11:36 PM
#5
Thanks for the info guys. The car was bought with the intention of being modified, and because I have some spare cash and a lot of free time this winter I'm willing to attempt anything. (Eventually an LT1 when I blow the stocker up.)
The ZF6 seems like a better option, more bang for your buck. Since the car won't be driven at all this winter I won't really mind having it out of commission as I scavenge around for parts.
One things for sure, and that's that I'm going to train my brain to use all 6 gears, as all my previous cars have been 5 speed sticks.
The ZF6 seems like a better option, more bang for your buck. Since the car won't be driven at all this winter I won't really mind having it out of commission as I scavenge around for parts.
One things for sure, and that's that I'm going to train my brain to use all 6 gears, as all my previous cars have been 5 speed sticks.
09-07-2007, 12:37 AM
#6
Team Owner
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Location: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
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In that case here's your parts list. You'll also need a clutch pedal, pivot, brake pedal, and a clutch master cylinder spacer (corvette central is the only one that has this)
Also forgot to mention you'll ABSOLUTELY have to put in a shorter rear end ratio if you go to ZF6. The TKO will also be bad with your current gears, but not as bad. Research this and what RPMs you'll see in 5th/6th, and costs of upping the rear end, and factor into your decision.
Here's the rest of the parts list:
89-93 black-tag ZF6 and 89-93 clutch set
(or 94-96 blue-tag trans and 94-96 clutch)
stock flywheel from manual trans vette of your year
91-96 bellhousing
89-96 clutch fork and pivot stud
88-91 starter
89-96 clutch master cylinder
89-90 clutch slave cylinder
89-90 clutch slave hose
(I recommend using the 91-96 clutch slave & hose, the bleeder on mine rubs against the tunnel)
89-96 driveshaft slip yoke installed on my 85-88 manual driveshaft
TH400 rear seal, Timken #9449 (if the rear seal on your ZF is in doubt.)
backup switch connector, a.k.a. horn connector. (AcDelco PT1357 or Napa ECHEC11)
(5) metric M12 x 45mm transmission bolts
(6) standard 3/8 x 1-3/4" pressure plate bolts
(I recommend mcmaster.com for these oddball sizes. Be sure to get the high-grade flange bolts)
17mm allen driver socket attachment for fill & drain plugs. (Available at autozone/kragen in a 3-pack)
3 bottles of GM 1052931 or Pennzoil Synchromesh
sheetmetal and rivets for patching the trans tunnel, and some extra carpet insulation.
Speedo sensor from my 85 4+3 fit the ZF6. I bought a red 37 tooth driven gear from GM for it to match my 3.07 rear end ratio. Getting the 37 tooth driven gear to mesh requires installing the speedo sensor upside down and tweaking the hold down clamp a bit. The 3.07 rear makes 6th gear unusable under 85mph. I recommend upgrading to a 3.45 or 3.55 ratio.
Go here for speedo gear selection:
http://webpages.charter.net/khasting...peedocalc.html
Here's a guide with all the part numbers and applications you may need for getting stuff from the salvage yards.
http://home.san.rr.com/khastings/ima...hpartslist.gif
The stock 85 battery cable (+) is long enough to reach the 88-91 ministarter. It required bending/cutting the end of the cable to fit the starter terminal and rerouting the battery end of it to come at the positive terminal from the 9 oclock position for extra reach.
Also forgot to mention you'll ABSOLUTELY have to put in a shorter rear end ratio if you go to ZF6. The TKO will also be bad with your current gears, but not as bad. Research this and what RPMs you'll see in 5th/6th, and costs of upping the rear end, and factor into your decision.
Here's the rest of the parts list:
Originally Posted by CentralCoaster
89-93 black-tag ZF6 and 89-93 clutch set
(or 94-96 blue-tag trans and 94-96 clutch)
stock flywheel from manual trans vette of your year
91-96 bellhousing
89-96 clutch fork and pivot stud
88-91 starter
89-96 clutch master cylinder
89-90 clutch slave cylinder
89-90 clutch slave hose
(I recommend using the 91-96 clutch slave & hose, the bleeder on mine rubs against the tunnel)
89-96 driveshaft slip yoke installed on my 85-88 manual driveshaft
TH400 rear seal, Timken #9449 (if the rear seal on your ZF is in doubt.)
backup switch connector, a.k.a. horn connector. (AcDelco PT1357 or Napa ECHEC11)
(5) metric M12 x 45mm transmission bolts
(6) standard 3/8 x 1-3/4" pressure plate bolts
(I recommend mcmaster.com for these oddball sizes. Be sure to get the high-grade flange bolts)
17mm allen driver socket attachment for fill & drain plugs. (Available at autozone/kragen in a 3-pack)
3 bottles of GM 1052931 or Pennzoil Synchromesh
sheetmetal and rivets for patching the trans tunnel, and some extra carpet insulation.
Speedo sensor from my 85 4+3 fit the ZF6. I bought a red 37 tooth driven gear from GM for it to match my 3.07 rear end ratio. Getting the 37 tooth driven gear to mesh requires installing the speedo sensor upside down and tweaking the hold down clamp a bit. The 3.07 rear makes 6th gear unusable under 85mph. I recommend upgrading to a 3.45 or 3.55 ratio.
Go here for speedo gear selection:
http://webpages.charter.net/khasting...peedocalc.html
Here's a guide with all the part numbers and applications you may need for getting stuff from the salvage yards.
http://home.san.rr.com/khastings/ima...hpartslist.gif
The stock 85 battery cable (+) is long enough to reach the 88-91 ministarter. It required bending/cutting the end of the cable to fit the starter terminal and rerouting the battery end of it to come at the positive terminal from the 9 oclock position for extra reach.
09-07-2007, 08:00 AM
#7
Melting Slicks
Member Since: Oct 2004
Location: Knoxville Tennessee
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Great post Coaster! I installed a T5 5 speed in my 79, had to make a spacer and scrounge for parts all winter. I'm seriously considering doing the same thing with my 92. Your post will help everyone considering this swap! If you have pics of the swap I would love to see them. I still get PMs of the swap I did 2 years ago. 
Bernie
Bernie
09-13-2007, 01:38 PM
#8
Team Owner
I'm seriously considering swap the auto with a ZF6 on my '85 as well. I've seen new ZF's going for around $1500 which doesnt sound too bad to me. The only part that concerns me is how to install the clutch slave/pedal assembly thing. I would gladly trade up for a newer one but I have yet to find a 6 speed vette for under $10K.
09-18-2007, 12:12 PM
#9
Team Owner
Member Since: May 2002
Location: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
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I'm seriously considering swap the auto with a ZF6 on my '85 as well. I've seen new ZF's going for around $1500 which doesnt sound too bad to me. The only part that concerns me is how to install the clutch slave/pedal assembly thing. I would gladly trade up for a newer one but I have yet to find a 6 speed vette for under $10K.
I can't help you with the pedal install, but I don't suppose GM minimized the firewall and floorpan differences to reduce tooling/mfg costs.
10-11-2007, 11:13 PM
#11
My mechanic did my swap a few years ago in my 85 while I had the engine out for a complete high performance rebuild. I did the ZF as well and I love it. However, my engine is pretty stout (360rwhp) and my OEM style Valeo clutch/pressure plate set up did not last long and my car is not a daily driver; ate the friction disc down to the rivets in 3 years and not many miles; also if you go to a single mass, aluminum flywheel like I did, the ZF will rattle like a box of rocks in neutral unless you engage the clutch when at idle; some people never get use to it; the EOM dual mass flywheel make the ZF much quieter, but it is expensive and heavy. Having said that, I enjoy my Vette more now after 6 years of ownership than I did when I first got it. I bought my car as a project car as well knowing I was going to tear it apart. It's fun to have an LS1 killing "sleeper L98."
1985, auto, c4, central, centralcoaster, coaster, conversion, corvette, l98, manual, swap, trainmission, trans, transmission
