Engine vs Trans vs gearing

[Ultrasummer]

Originally Posted by typerr

I'm in the middle of doing an upgrade from my original Saginaw 3-speed (which had already been converted to floor shift) to a freshly rebuilt T5 WC 5-speed that once lived in a Camaro. I'm using an S10 tailhousing & mainshaft to work with my bench seat. I've also got 3.73 rear gears and the .63 overdrive gear will go a long way to reducing revs on the highway. If you aren't afraid to take things apart and put them back together this upgrade can be done for not much cash.

I'd be curious to hear what you think of that set up when it's done. I did a little reading on it. Sounds like the T5 from a Chevy S10 1988 and earlier is the best match with the least amount of headache.

[jocko]

Recommend read up on the T5 swaps. Yes, an S10 tailshaft simplifies stick location in a bench cab, but S10 trans also requires input shaft spacing. The best of both worlds is a Camaro trans main body (no spacer required) with an S10 tailshaft. That, of course, requires two transmissions or a lucky craigslist franken-find. I prefer to use an S10 WC with a spacer. take a look here

Keep in mind that if you change rear gear only, your granny gear dilemma remains. A 3.07 rear makes granny slightly less granny, but not much - but also note, 2nd gear will have less acceleration than it already has - and if that's what you start off in, you'll notice the difference. Higher rear gear (lower numerical ratio) only improves your highway rpm problem. Also keep in mind that if you do a 3.07 rear only - and then decided to add an o/d trans later - rpm a lower highway speeds would be too low and you'd risk lugging the engine. So, if you want to go the 3.07 "only" route, make sure you're committed to stick with your trans (or a trans with a 1:1 final drive), as most overdrive transmissions + 3.07 result in TOO high of a highway ratio and low rpm.

[Ultrasummer]

Originally Posted by jocko

Recommend read up on the T5 swaps. Yes, an S10 tailshaft simplifies stick location in a bench cab, but S10 trans also requires input shaft spacing. The best of both worlds is a Camaro trans main body (no spacer required) with an S10 tailshaft. That, of course, requires two transmissions. I prefer to use an S10 WC with a spacer. take a look here

Keep in mind that if you change rear gear only, your granny gear dilemma remains. A 3.07 rear makes granny slightly less granny, but not much - but also note, 2nd gear will have less acceleration than it already has - and if that's what you start off in, you'll notice the difference. Higher rear gear (lower numerical ratio) only improves your highway rpm problem. Also keep in mind that if you do a 3.07 rear only - and then decided to add an o/d trans later - rpm a lower highway speeds would be too low and you'd risk lugging the engine. So, if you want to go the 3.07 "only" router, make sure you're committed to stick with your trans (or a trans with a 1:1 final drive), as most overdrive transmissions + 3.07 result in TOO high of a highway ratio and low rpm.

Interesting. That changes my feelings on just the rear gears. Thanks for the info on the transmissions. I'll dig into that info

[67 twins]

I'm another fan of the T5 with 3.73 rear gears. This is what my wife's truck has & it is a very fun beast to drive. At the same time the OD gearing on the highway is perfect for cruising

[71gmcC15]

I have a 307 4 speed with 3.73 rear gears. It's about 3000 rpm at 65. Tires are 29 inch tall if I remember right. I go 55. It's about 2300rpm.

[typerr]

Originally Posted by jocko

The best of both worlds is a Camaro trans main body (no spacer required) with an S10 tailshaft. That, of course, requires two transmissions or a lucky craigslist franken-find.

I bought my Camaro T5 from a seller on ebay who did the S10 swap as part of the deal. Granted the Camaro T5 WC's do not grow on trees like the Mustang versions but they are out there if you are persistent. Should have my swap wrapped up in a couple more weekends. I'm also doing a hydraulic clutch and sound insulation while I have the carpet out.

[jocko]

Originally Posted by typerr

I bought my Camaro T5 from a seller on ebay who did the S10 swap as part of the deal. Granted the Camaro T5 WC's do not grow on trees like the Mustang versions but they are out there if you are persistent. Should have my swap wrapped up in a couple more weekends. I'm also doing a hydraulic clutch and sound insulation while I have the carpet out.

That’s the way to do it. Since starting from scratch on the swap i did, I’d estimate about 75% of my time was spent designing/building an input shaft spacer. They are available aftermarket now of course, ha! I went with stock linkage just for simplicity’s sake. But if running headers, hydraulic gives you a little more space. Are you doing a hydraulic slave cylinder or a hydraulic release bearing?

[tdangle]

Pretty much the rule with today's highway speeds is with at 1 to 1 final drive ratio on the trans, don't go lower than about 3.5:1 with the gears. An overdrive trans (usually .7 or so) go with 3.7 to 4.1 I have a OD auto trans with 4.10 and it is a nice combination.

[typerr]

Originally Posted by jocko

Are you doing a hydraulic slave cylinder or a hydraulic release bearing?

I'm going with a Tilton hydraulic release bearing coupled with the Captain Fab pedal linkage and master cylinder kit. Great quality and support at both ends of the system.

[jocko]

Nice setup! Sounds like fun.

[my67c20]

From your original post it sounds like you do occasionally hit the highway, but did not mention use of the truck, or a possible budget. Doing an automatic w/overdrive swap is not all that difficult. If you are not worried about removing the clutch pedal, having a neutral safety switch, back-up lights or a column shifter, it only gets easier. Its is easy enough to add a cooler, connect kickdown linkage, vacuum line and have the driveshaft modified. If you wanted to get a stock look, there are plenty of people parting these trucks to find all the parts needed for under $500. Recently swapped out the SM465 for a TH350, with 3:73 gearing. Probably could have completed it in a weekend, if I did not want to clean and paint everything. If automatic is not your cup of tea, then look at doing a NV3500 swap. Plenty of kits and posts about this change. Changing the rear gears only will get you some highway benefit, but will affect low speed drive-ability with the SM465, hence finding and overdrive. Another option, although more expensive, would be a gearvendors OD. Nice part of this option, is that if you ever wanted to sell the truck, just remove the unit and use on the next. These trucks are noisy and a 307 at 3000 rpm sounds like its gonna fall apart. Bottom line, you need to knock the RPM's down.