Inliners International Forums General Discussion Drive Train T5 Cruising RPM's

Was wondering if someone with a 235 AD truck/T5 could recommend a ring/pinion ratio that would keep my RPM's in the correct range.

My engine is stock, T5 has a .72 OD, tire height will be between 28-30". I have a choice of 3.08, 3.42, 3.73. Most driving will be on flat land@ 65 mph.

I've done all the RPM calculations but would like to hear from someone who actually drives this, or a similar combo.

In other words, what RPM's in OD would keep my 235 happy without having to shift into 4th at the slightest incline?

Thanks in advance, Dave

Dave,

I have the same tranny but with a little larger motor (292). I put a 3:55 rear in my Coupe and I never have to downshift into 4th when pulling a hill or passing a semi. I have 31" tires in the back and at 65 mph it's taching 1850 rpms. I would think your 235 would like that range. I get 18-20 mpg too with 3-2's! If you are running a 1- bbl, you might be pushing the pedal harder than if you were running a H/W progressive 2bbl.

I would think if you're cruising all day at a constant speed, the 3:42 would work quite well.

RapRap
1940 ChoppedChevyCoupe

Hey Chopped 40,

Thanks for the response! I've been trying to get a handle on the 235 power curve. Don't see any reason for needless revs but also don't want to be lugging the engine in 5th.

The 55-235 max's out it's torque at 2K. If I went with 31's, 3.42,@65 I'd be turning 1735, same combo with 3.73-1892. My 3.42 is a low mileage Camaro 9 bolt Australian with outboard discs. Not real popular compared to a 10 or 12 bolt but available in the correct width. Any suggestions?

A pair of Weber's, cam/headers are in the near-future...she's headed for the paint booth next week so I've got a little time to crunch the numbers and get some good advice.

Thanks again for your input! Dave

Dave,

Sounds good to me.
The Webers and cam should make your motor run very well. Any clean up you can do in the intake/exhaust/valve area will definately bring more results and better all around performance. Porting and polishing is the easiest to do. What width is your stock differential? I measured from backing plate to backing plate. I believe the Camero was 61". I used a 1968 nova which has a 60" width so I could use wider tires and offset rims. I run 15"x8.5" rear wheels with a 3.5" rear offset. The tires are Diamondback Classics 275-75/15. 31" tall by 9.5" wide. Big mommas and weigh approx. 50lbs each mounted. funny, I don't have any problems spinning the crap out of them!

RapRap
1940 ChoppedChevyCoupe

C-40,

Ubetcha on the upgrades. I'd be a little more comfortable if the 235 was a 7 main engine..Phase 1 of my project has been getting all the panels in the 5 window, short-bed replaced, dual master and basically back to stock configuration. Currently Granny 4 speed with torque tube (3.90). Paint booth next week.
Phase 2 will hang the T5 (electronic),slide in the open drive diff, add discs to the front and plumb in the rear discs,sway bars, rims and tires. Phase 3 will be the kicker....HEI dist., a couple Webers, mild 3/4 grind cam, headers, some bench work on the head, a set of electronic gauges. So far I've got 400+ hours in this project...probably another 400 to get it buttoned up. I'm retired so 50+ hours a week is about all I can stand!!!lol

Not sure if I'll run a 15 or 16" rims (5 lug)but 75 series tires will get my wheel wells filled up. The stock diff width is 62.25" and the 88 Camaro 9 bolt w/discs is 62" from wheel mounting surface to mounting surface. I considered a Nova diff. but down here most have gone to China as scrap. Both T5 and 9 bolt were from tree crushed vehicles from Hurricane Charlie...38K on both so no immediate rebuilds...I hope!!

Might even get it good enough for some pics!!

Dave