The Stovebolt Site Forums The Shop Area The HiPo Shop T5 Woes!

I hate it when a plan doesn't come together!

Naw, it's not the T5..it works great, smooth and it really makes driving a hoot. The bone stock little 235 with 29" tires and a .72 OD scoots around town with ease in 4th gear. It's when you get out on the highway @ 65mph and shift it into 5th and the RPM's drop back to 1670. It's way to tall a gear (3.08) for even the flatland. Being that I want to cruise at 65-70 mph I should have gone with the 3.42 or maybe even a 3.73. Also noted that my oil pressure at the lower RPM was suffering a bit.

Maybe it was just the fickle-finger-of-fate or the posi/discs that attracted me to this obvious "automatic" diff but it's time to bite the bullet and start scouting up a 3.42. Probably won't be able to find one with discs, which incidently are awesome (non-power) but you never know!

I guess what I'm trying to say is that if you're contemplating a diff for your 235/T5 combo you might be wise to stay away from the tall stuff and give the 235 a little extra RPM's to be happy.

I hope this helps someone avoid the problems I've created for myself.

Dave

Glad to hear the T-5 is working good for you.

So, what ratio rear end did you use in your 54?

If your thinking 3.42 or 3.73, another choice might be right between at 3.55.

Joe

Seems like you already have modified the rearend to fit.Why not change the ring and pinion,and keep the discs ?

I am going with the 3:73 gear ratio with the t-5.I just picked up my driveshaft on friday.I still have the 216 in the truck,so i will see how it pulls with it,my 261 will be in the truck soon.

I used an Australian Borg Warner 3.08 posi/disc from an 88 IROC-z....62" wide, disc brake emergency cables tied right in with stock setup. Knew it was too good to be true. It was behind a stick 305 V8. These diffs came with only the 3.08 or 3.42....the j-yard swore it was a 3.42....never assume...should have pulled the cover before I loaded it up.

I'll search for a 3.42 but am pessimistic....I passed up a mid-70's Camaro 62" diff sitting right beside the IROC. It was a stick-shift V6 drum brake diff and could have got it for 1/2 what I paid for the "Z" diff.

As for changing out the R&P....just a few vendors carry the Aussy Borg 3.42 and it's pricey. Guess I'll just bug around in 4th until I stumble onto a 3.42.

The sad part is that the 3.08 is great around town....about 1600 RPM's up to 50mph. It's just when you dump it into 5th that the bottom drops out and it's "Lug City". Don't like to do that to a sweet little engine and I really don't need to cruise at 85. Oh well, back to the drawing board!!!!

You're right,they are pricey. $450.00 to $500.00 for a ring and pinion,wow !!

Yep...and the calipers were dear too....should have gone into the Vin# with a bit more enthusiasm...the only tag on the diff indicated that it was a "non slip"...no ratios or other numbers. Didn't get the bad news until I popped the cover.....oh well.

I've heard that the S10 Blazers (4wd) have a 62" diff....hopefully, somebody that has spent time crawling around in the junkyard will pop in with some good suggestions. Till then, I guess I'll be driving it like a 4 speed and keeping my eyes open.

Thanks for your responses.

Change the overdrive ratio.

William Schickling did a lot of resarch on the T-5 gear ratios for his '40 and documented most of his work on his web site. He was able to change his OD to suit his needs by getting a couple of gears from Ariel Gear. He hangs around here sometimes and maybe can give you some idea of what's possible.

It sounds like you might have the 0.63 OD and need something not as tall. From his web site it looks like he was working from the other way around.

William Schickling\'s 1940 Chevy Pickup T-5 page


Oops, I dust reread your post and you said 0.72 OD. So the question is, would a 0.86 OD make enough of a difference to jusify the rebuild?
That is assuming you do have a 0.72 OD

some late eighties v6 camaros are 3.42s.i have one in my rs.sounds maybe like a good time to lower it and run shorter tires.

Late production ('99-'04) S-10 Blazers (2 and 4 wheel drive) and 4x4 trucks have rear disk brakes.

Just rebuilt the T5 so I really hate to go back inside...a .86 OD would only give me 325 more RPMs..up to 1995...the 255/70/15" tires are new and I like the more stock stance. I was hoping 1700 rpm would cut the mustard but I think it's going to take 2000 to make her feel "right" in OD @ 65mph.

Guess I might as well bite the bullet and scout up a 3.42....should have looked at the less exotic V6 RS diffs....cleaning off the Camaro mount hardware isn't that big a deal and maybe the extra grunt will teach me to "assume" nothing.

Thanks for your responses folks.

Is your 235 tired? I would have guessed this combo would have worked. Joker has 273 rear and a t-5 and says he pulls overdrive fine. The stock 235 puts a lot of torque out at the 1500 - 2000 rpm range. I find it odd that at 1700 rpms that old girl won't pull.

I am asking so many questions because I was planning to run at a similar rpm range for maximum fuel efficiency. My numbers would give me about 1900 rpms at 70 mph. I don't have the rear or the trans yet, so I could change that. I am also running a 302 gmc which is a little more stout than that chevy. I was thinking that it would be a quieter ride to be just under 2000 rpms.

I am running a blazer rear end,2:73 and s-10 five speed..the over drive works ok if I am flat land,, but depending on traffic or grade, I may have to down shift.. but it will slowly pull up to how fast you want it..like he says, you do lose rpm's when you go into fifth,, and if you wanna pass someone at 70, it may take awhile.. I have driven mine over 2 yrs and it is ok...but yes,, with that gear or mine you may lose a little ump.. but then if you have the 3:73 you may loose some gas mileage in city driving..

shouldnt be that hard for me to change ring/pinion if needed............I am running a 205/75r/15 tire,, dont know if that makes a diffence as compared to Fla54......

Tired....naw, good compression, no blow-by, good oil pressure, 2bbl H/W......timing on the money......maybe my expectations were a little high.

Tall 29" tire diameter doesn't help things any. For now I'm going to put some more miles on her and see if maybe it might be that I'm trying to overdrive this combination. I wasn't shooting for a rocketship but I've been building for a lot of years and just didn't think I could miss the mark but this much.

Actually, it'll give me a reason to play around with some other options and come up with the right combo to give me the power and mileage I was seeking. I know the little 235 has it in her...I've just got to dig it out.

Thanks again guys for jumping in....a lot of good suggestions/comments and I really appreciate your input.

i have a 235 with dual carbs and exhaust with a 2.73 nova and it pulls just fine. i live in central indiana and there hills on the highway between my house and town and it does ok. i have 235/75/15 tires. btw i am having the engine overhauled because of a broken piston ring and two burnt valves and it still held its own in traffic.

FLA,

I have been keeping my eye out for the "right" rear end to put in my truck. The one I am looking at is out of a trailblazer. The width is right and I think they come with discs, The 2007 specs show they run a 3:42.

Does anyone have any insight on this rearend? Would it work along with a T-5? I can get for about $300 from the boneyard.

Nice to hear from you 2.73 guys.....I'm not rushing out and chucking the 3.08. It could very well be that I'm jumping to conclusions too quickly. I'm going to give it a little time...it's absolutely great around town and do some "open road" driving where I can get the feel of the machine....also will stick on my vacuum gauge to see what's happening inside the 235.

I like to putz along at a modest 60-65...probably P.O. some speedsters but maybe I'll just have to kick it up a notch and join the crowd when I'm on the big road. Probably will stick on some upgraded tierod ends and possibly a steering stabilizer. Right now she runs true as a bullet but there's no sense pushing my luck.

I'd like to presonally thank all of you who have offered suggestions, advice, and encouragement during my project. If you ever get down this way, I'm in the book. Won't take you to Disney but can put you on some primo bass fishing and I know where to find good Florida style home cooking. Thanks again!

Dave

BTW...46 in progress, I found that the late model ABS diffs were out of sight moneywise. The mid-late 80's Camaro's were about the only ones you could touch without a mortgage.