Tremec swap to SM318 bellhousing? measurements on bell? (GMC)

[Chuck78]

I'm looking at options on a 5 speed trans... seems that I can retain the stock bell and starter, etc if I swap in a Dodge NV4500 with an adapter plate between the trans and bell. NV4500 isn't really what I wanted (heavy, and granny gear). A T5 would be ideal if it'd hold up to towing a car trailer once a year or so... Not so sure on that. Truck previously had a T5 swapped in, but last owner yanked it out, and I never got the details of how it bolted up. So that leaves an NV3500 or maybe my Tremec TR-3550 for my Camaro (like an older TKO500). 3.27 first and OD 5th... Bolts up to the same bell that a T10, ST10, Muncie, Saginaw, etc bolts to, which I believe is a T5 pattern also... Nv3500 means I need a $1000 adapter kit with starter and crank spacer, etc... NV4500 bell to trans adapter is only $300!

Anyways, I tried to measure my stock bell bolt pattern, and compare with my Tremec (new in box still). Looked to me that the Tremec pattern was almost the same, but the bottom holes were about 1/4" wider or narrower. Also, the input bearing retainer that acts as a bore register, not sure if it'd be the same diameter between the SM318 and the Tremec.

Lastly, how do you deal with the T10/Tremec/Muncie style where the bell is threaded on all 4 holes, but the SM318 style of the bell where two bolts thread into the bell, and the other two into the trans? Just nut and bolt it?


If someone could measure their bellhousing and post side to side and up and down measurements on the trans ear bolt pattern, and measure the input bearing register diameter, that would be MUCH appreciated... I have a GMC, so the block is an oddball that makes trans swaps difficult...

Thanks!

Chuck

[billydonn]

Tremecs are available that bolt right on to the common Chevrolet bellhousings, so I don't see why they wouldn't work the same with a GMC. And you can get the Tremec bearing register in either of the two Chevrolet sizes (slightly less than 5" for the 60s Chevys, I believe). Could you be more specific about your truck, please?

Some Chevy trannys did use a bolt and nut on the bottom two bolts to the bellhousing.

[greg64]

The common Chevy bearing register is 4-11/16". The SM465 is an oddball at 5-1/8, and I believe there's some wimpy trannys that are under the 4&11, but they won't interest us.

I want the same thing in my burb (half decent 5 speed), but the T5 is a bit wimpy for my liking, and the NV4500 is expensive, heavy and not as good as it was originally cracked up to be.

This site has a ton of good information:
http://www.novak-adapt.com/knowledge...on_gateway.htm

Anyway from all of the above, I'm planning on going with a TKO-500, but this is hardly a cheap option. I just can't see anything else that:
1) fits a standard bellhousing will no goofing around
2) can take the torque of a V8 (where a T5 falls down) especially when towing
3) has lots of shifter position options so that it's close to stock (also a T5 weak point)
4) has overdrive (otherwise I'd use another SM465; great tranny)

The flip side is at today's gas prices, the overdrive will eventually pay for itself, plus I figure the TKO will be good for the life of the rig assuming it's not abused.

As for the bell to tranny bolts, I wouldn't worry if you have to nut and bolt it (both holes clear, not tapped). The register centers the matchup, the bolts just take the torque and the bending, and a nut and bolt can certainly handle that (I'd use a nyloc nut).

Anybody have another good suggestion that makes me think I'm smoking drugs here?

[ChiefRocka]

Sorry to hi-jack, but would the T-5 bolt up to my 3-speed housing ?? Is that the tranny out of an S-10 ?

Thanks

[kdrodworks316]

hey Cheif, I dont know about your bell, but yes they came in s10's and camaros, TA's, mustangs, and some rangers. the s-10 is the one with the more forward shifter so you can keep a bench seat

[Rogue 64]

There is alot more to it. World Class, Non-WC, Speedo, 17*, shifter, etc, etc, etc,
Do your research, on Stovebolt and Inliners.

I am just gonna put a TKO, and be done.
http://www.standardtransmission.com/

[Captainfab]

I may be wrong but I was thinking that the T-5 had a different bolt pattern than the standard Chevy belhousing.

The bolt pattern on a standard GM bellhousing is 8 1/4" side to side on the top holes, and 9 1/8" across the bottom, with a verticle measurement of 4 13/16". The pattern is a rectangle except for the lower right hole being offset to the outside, hence the 7/8" difference across the bottom.

As already stated you shouldn't have and problem getting an aftermarket 5 spd to bolt up, even though it sounds as if you have the V-6.

[Chuck78]

Okay, so I measured both my Tremec 3550 and my SM318 in the truck. The truck does appear to have the standard trans ear pattern on the bell (sigh of relief!). The bottom would need to be nut and bolted on a Muncie/Tremec/etc, but should line up. Mid shifter location seems like it would do it for the Tremec's. Front looks pretty far up. My Tremec is a rear mount shifter, and also would be perfect for my 3.23 Camaro posi rear, and already have a Lakewood blowproof sbc bell for the camaro... Might look into another TR-3550 used, or else bite the bullet and buy a new one for the Camaro down the road, or else swap in a T56 and a 3.73 to the 71 Camaro in about 5 years when it is more likely to get back on the list of priorities...

My only concern now is the input bearing retainer's bore register diameter. It's the same as a Muncie/T10/ST10/Saginaw, and looks to me like about 4-5/8" or 4-11/16" (have to find my calipers to get it exact). Is this the same as the SM420 and more importantly, the SM318? The reason I am concerned is because of a random truck bell that my dad inherited that looks bulletproof, which I was going to use until I realized the bellhousing register was a much larger size (must have been an SM465??? had a 5th mounting hole on the bottom in the middle, lower than the standard 4 which matched the Muncie/Saginaw/T10/etc.)

My dad still has that bell, if anyone is needing one.

Anyhow, it sounds like this Tremec is a shoe-in if I had a mid shifter kit. It'd work for now in the hole someone cut for a T-5 rear shifter (bummer, hard spot to fab a patch for). If someone could just verify for me that the bore register is in fact a 4-11/16 or 4-5/8" on the SM318, then I'd be set...

If I found a deal on an NV3500, might go for it still... Current 3.23 Camaro posi + New TKO = $1800+ for Camaro, or 3.73 gears + T56 for Camaro = pricey, but then I could use my Camaro slated trans for the truck as is or with $350 mid shifter kit...
Otherwise it's looking like Tremec in Camaro, and then NV3500 ($400-$800 used?), + $1000 adapter kit w/starter, plus electric speedo or else magnetic to mechanical adapter... Either way, $2G's - now or later is the question I suppose. Later sounds better! Too bad I sold both Super T-10 4 speeds for the Camaro. I have a 700R4 auto as a spare if I was in a pinch!

Thanks for the help!

Chuck

[greg64]

Chuck, I don't know the SM318's diameter, but the bellhousing is 4-11/16 or 5-1/8 (the SM465 one). Plus, the Muncies and T10, etc. use the 4-11/16, so I'd be really surprised if you're going to have a problem here.

As for the T5s, they are weirdos. I'm pretty sure there are input shaft problems if you were to use them behind a SBC, although that is what was done in the 3rd gen Camaros, but again, that's a bit weird because the bellhousing in that application rotates the transmission off the vertical. So, it's possible that this corrects for the input shaft as well.

The S10 T5s I'm familiar with were used behind the 2.8V6 and 4cyl, and the V6 has a bellhousing that is different from the standard Chevy V8 design.

I think the bellhousing that can match the two is the one from the Astro van with the 4.3V6, but how many of those had a 5 speed?

Bottom line, if you're considering the T5, do your research because there's been a lot of variants over the years (especially when you consider the Ford application with the WC-World Class).

[raycow]

Sorry to dredge up a 2 y/o thread, but can anyone shed some light on the$1000 NV3500 adapter kit that Chuck78 is talking about?

I have looked at a few of these transmissions and they all had what seemed like a normal Chevy bellhousing except for the fork and slave. I know I would need to convert to hydraulic clutch linkage and also get either a Cable-X or an electric speedo, but there is no way I can see $1000 there. Please tell me what the adapter does and, if possible, post a link to it.

Thanks in advance.

Ray

[Chuck78]

This is for the 60's era heavy duty, truck/heavy-equipment-only big block V6 engine family. The trannies are the same, the block to bell pattern is unique to the GMC V6's, V8, and V12 of the era. The adapter to mount an auto trans (obviously integrated bell) to the GMC engines is $1000. Engines were 305, 351, 401, and 478 in the V6 (and two others like 379 and 43-?, more rare and beyond the 60-66 passenger truck line useage), as well as a 572? V8 and the 702? V12 that used 4 V6 heads and two V6 intakes, one block/crank/cam.

The talk of NV4500 adaptation to the GMC truck V6 is I believe due to the 4500 having it's own bolt pattern, trans to bell. You can run a Dodge version I think, with hte longer input shaft of same diameter, and use a cheaper adapter plate between the trans and bell for that application to use in a non-chevy block to bell pattern.

[raycow]

Chuck, I understand completely now. Even though it says GMC right there in the header, I didn't pick up on the point that you were wanting to bolt the transmission up to a V-6. Now it all makes sense. Thank you for taking the time to explain.

Ray