Can't wait!

 

So another fairly long day working on the trans. I pulled the dust boot off one of the other trans cases I've got lying around and swapped it to this case. I did some research on proper preloading of the bearings (admittedly on DSM forums which are a great resource!) and found that using rosin core solder works quite well to get a measurement. You place three pieces of solder (I cut them 1/2" long) around the top of each bearing race and put the mid half of the trans case on and torque it to spec. Then you remove the top half and measure the solder (which will have crushed) to get a clearance measurement. I'm not sure what the spec's for pre-loading are but average on the DSM forums I found was around .002-.005" (.006-.008" for drag racing transmissions). Here are some photos to explain:















So I've found the following measurements:



Input shaft clearance: .068" - I coincidentally have a custom made .071" shim for this bearing race, so .003" preload which is perfect!



Output shaft clearance: .086" - I do not have a shim for this clearance, figure I'll have to have a couple made. I'll probably go with a .088 and .089 and use whichever one feels best once installed with the case torqued.



Differential clearance: .031-.032" - I found an OE shim that's .033" so I'm planning to use it, I may have a couple of additional shims made at .034 and .035" since I've got to have some custom made anyway (what isn't custom with this damn car!?).



Had to do some minor clearancing of the case for the pinion gear:









Here are some additional photos I took (eye candy):



















As you can see, these two gears (2nd) aren't perfectly meshed. Shimming the bottom of the shaft would put all of the other gears off center so it is what it is, I don't think it'll cause much of an issue but I'm a little OCD so I noticed it.











Here's an image of the 4th gear pair (as you can see they're close to dead center):









I also counted teeth on the old and new gearsets to get the ratios:



Old:



Pinion - 19 , Ring - 73 = 3.842:1

1st - 13 In , 43 Out = 3.307

2nd - 20 In , 39 Out = 1.950

3rd - 33 In , 39 Out = 1.181 (not sure why this is lower than 4th?)

4th - 28 In , 35 Out = 1.250

5th - 43 In , 36 Out = 0.837



New:



Pinion - 17 , Ring - 53 = 3.117:1

1st - 10 In , 32 Out = 3.200

2nd - 12 In , 26 Out = 2.166

3rd - 15 In , 24 Out = 1.600

4th - 18 In , 22 Out = 1.222

5th - 20 In , 20 Out = 1.000





This puts my top speed with the new trans the same as the old trans (due to the 1:1 5th gear ratio vs. the factory's overdrive 5th), still 170-175 depending on tire size which I don't think I'd want to exceed without a cage anyway lol. However it will put me about 15-20 mph faster in every other gear according to the spreadsheet I used. I'll have to wait to get the custom shim made up as I'm not half assing this assembly! Hopefully it's the last time I have to take the transmission apart...

 

You probably checked but how was the clearance between flat side of the ring gear and that bottom shaft gear? Maybe there's some wiggle room there to get the other gears to line up better? I'd had to have you spend all this timing an money and have issues due to improper gear mesh.

 

There may be a bit of wiggle room there (a few thousandths of an inch), but to get the race out of the case would prove very difficult. It was almost a pressed fit even after heating the case and cooling the race, and it's a blind race meaning there's no way to get to it from the back. I wouldn't want to destroy the case trying to remove it to put a shim under it. In addition, there is an oil funnel type device that goes under that race so I'm not sure a shim would function properly there. I doubt there will be an issue, still waiting for a response from PAR to be sure.



If there is an issue, I think it'd be easier to press the bearing off the shaft and add a shim between it and the machined surface it is pressed against to effectively raise the gears and get perfect lineup. Of course either way I'd have to have more custom shims made, OH JOY!

 

Hopefully PAR gets back to you in less than 9 months..



If it were me I'd be exploring the custom shim job right away to get it right the first time before you go applying 500ft/lbs of torque to those gears. Do you have a local trans shop you can take it to for their opinion?

 

If it were me, I'd have that case at least cryo-treated. They could also check for fractures. A broken case will damage the gears. Also, it wouldn't hurt to get a local opinion on the install. I don't know your background experience though, so whatever you think is best to protect that investment.....

 

Heard back from the manufacturer, .002-.004" preload is advisable and the slight mismatch is acceptable. There was some corrosion inside the top of the mid-case that I discovered. I'm putting it together and seeing how it goes. I'm unsure what VIN car I pulled this trans from but it's got the 5th gear synchro cone bolted to the under side of the 5th gear housing cover so I believe it's quite old. I've never had issues with cases so don't expect any problems there, if it does go these gears are so heavy/durable I doubt they'd sustain much damage. Plus they've each got their own part numbers etched into them for future replacements.

 

That looks great



Assuming you have a similar tyre size to me those ratios are going to be great for drag racing.







My trans build has just been completed with very similar ratios, I can't wait to collect it.



Best of luck!

 

I've been going over the pics in this thread lately and started to wonder how similar the stock input/output shafts are compared to the one that PAR made.



In theory if everything is machined the same way and everything is the same size, we could essentially toss the straight cut gears from PAR onto the stock shafts. Granted this would be if everything is the same. This would open up an option to use boost in 5th gear without worrying about it grenading. Hopefully tdonnell can chime in on that part.



Correct me if I'm wrong, but it looks like 1st and 2nd are fixed gears on the input shaft?

 

Thanks dmg210, I hope your set installation goes without issue as well! I've got the RPM limit set to 7500 so I can go a bit faster in each gear than your chart shows, but thanks for posting that up! It's nice to see it graphed out. I wanted to be able to get to 150mph in 4th for the dragstrip so if/when I get a larger turbo and put down some additional power I won't have to go into 5th. I do wish he had made 5th gear overdriven just slightly, I could've done texas mile stuff if so but oh well.



SpoolinShark: You are correct that 1st and 2nd gear are machined onto the input shaft. I do believe the PAR components could be installed onto the stock shafts if needed. I'll send Haysam at PAR an e-mail to see if he considers this a possibility. He may even be able to make an overdrive 5th gear set per request based on the numbers he's already got (shaft spacing etc.). That'd be neat and something I'd be interested in myself...



Oh and there's a machine shop only 5 minutes from my house that is going to make my spacers for me. I had some 3.000" stainless bar stock that I took over there for them to use (talk about a coincidence!). They said the spacers should be done early next week so hopefully the car is back together by the end of next weekend. I got the windshield replaced this morning so it'll be able to pass inspection (old one had a large crack at the top). I'll just have to convert it from E85/standalone to 93 and the factory computer with stock injectors, MAF, IAT, cats, O2, etc.