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-   -   LS1 Engine. Need Transmission Choices: T5 vs T18 vs ? (http://www.jeepforum.com/forum/f8/ls1-engine-need-transmission-choices-t5-vs-t18-vs-1224334/)

tlannom 06-07-2011 02:57 PM

LS1 Engine. Need Transmission Choices: T5 vs T18 vs ?
 
I have an 86 CJ7 with a Corvette LS1. I broke the main shaft in the current T5 transmission. GForce transmission says it shouldn't happen and to send the transmission to them for repair. Based on a little research it doesn't seem the T5 will last long behind the LS1. I have access to a T-18 but it's going to require new bell housing and a new output shaft for the Dana 300.

Option 1- repair T5 (approx $600)
Option 2- Spend more $ on the T18 (approx $1400)
Option 3- something else

I really don't use this Jeep to wheel all that much, but I am prone to put my foot in it around town.

Thanks for the help.

kickingprop 06-07-2011 03:07 PM

If you are married to keeping a manual tranny then I'd look for an SM465 or SM420. It should have the same bellhousing bolt pattern and then would only need to be adapted to the D300. SM465's are as strong at T18's and mostly easier to find. Granny gear is nice for wheeling too.

http://www.novak-adapt.com/knowledge/sm465.htm for a little knowledge

But I wouldnt waste time rebuilding a T5. I grenaded mine behind the 258 and opted not to keep it when I upgraded to the 5.3L LM7

I've been pretty happy with the 4L60E behind my 5.3 but long for the day I can get that third pedal back...

CSP 06-07-2011 03:14 PM

If you don't wheel much you probably don't want a transmission with a granny low first gear (like the T18 or SM465). The T5 shouldn't even be considered, especially behind any V8.

LT1CJ7 06-07-2011 04:06 PM

Looking back at all the problems you've had with the GForce, I'd junk it.
Do it once and put an NV4500 in.
I know it's not cheap, But it'll be cheaper up front than in the long run.
You get the best of both worlds with a 5.61/6.34 low first and a .73 overdrive.
You would be hard pressed to break it.

4lowherewego 06-07-2011 07:46 PM

x2 on nv4500. If going to keep manual... id go to nv4500 and be done with it and have all 3 pedals, granny gear, and overdrive, and unbreakable.

But, TH400, 4l60e could make potential auto choices.

DO NOT REBUILD T5....

lucdog 06-07-2011 08:50 PM

Is this the same T-5, that came stock in CJ's, or the one in think they used in Mustangs?

Bill

markso125 06-07-2011 09:07 PM

Quote:

Originally Posted by lucdog (Post 11672254)
Is this the same T-5, that came stock in CJ's, or the one in think they used in Mustangs?

Bill

I would say its the stock NWC T5 because its got a Dana 300 transfer case bolted too it. They never made a World Class T5 that bolted up to the D300. Well there is a company doing a conversion now but its still not worth it to have one of those behind a V8 with a 100+ LBS transfer case hanging on the back end...

kickingprop 06-08-2011 07:06 AM

The NV4500 may be a big strong tranny, but it has its own flaws and requires quite a bit more work to make it fit. Do you have a body lift? If not you are looking at doing some serious tranny tunnel trimming to make it fit. This is not a small transmission.

with the right gearing, OD isnt necessary and the 1:1 final of the SM465 or T18 gives good highway cruising RPMs and the deep granny still allows for crawling. NV4500's cost a LOT more as well...

LT1CJ7 06-08-2011 10:06 AM

Any upgrade we do costs time, money and something always needs to be modified.
Why do you think they are called mods ???
The 1:1 final 4 speed is only going to get you so far with the correct gear,
And is not able to be finer tuned like a 5 spd.
Low range speed, highway speed and you forgot fuel mileage.
No good trans swap is cheap to do.
If the op want's to stay 5 speed..... Go with the NV4500.

garretj64 06-08-2011 10:22 AM

Quote:

Originally Posted by kickingprop (Post 11673974)
The NV4500 may be a big strong tranny, but it has its own flaws and requires quite a bit more work to make it fit. Do you have a body lift? If not you are looking at doing some serious tranny tunnel trimming to make it fit. This is not a small transmission.

with the right gearing, OD isnt necessary and the 1:1 final of the SM465 or T18 gives good highway cruising RPMs and the deep granny still allows for crawling. NV4500's cost a LOT more as well...

I found my NV4500 for $500 last November, also its not too bad to make it fit either. It really is the best manual tranny for a powerful V8:2thumbsup:

LT1CJ7 06-08-2011 10:32 AM

Quote:

Originally Posted by garretj64 (Post 11674903)
its not too bad to make it fit either. It really is the best manual tranny for a powerful V8:2thumbsup:

:agree: :ditto: :thankyou: :highfive: :thumbsup: :thumbsup:

jeepdaddy2000 06-08-2011 07:39 PM

Quote:

with the right gearing, OD isnt necessary and the 1:1 final of the SM465 or T18 gives good highway cruising RPMs and the deep granny still allows for crawling. NV4500's cost a LOT more as well...
I tend to agree with this statement. Running 3.73's with 33's puts you in the ball park for a straight four speed. It also allows for larger tires in the future and eliminates the need to regear to 4.88's as the op is looking to do. The SM is a short trans and the adapter is small as well. The overall short length will help keep that rear driveline as long as possible, an issue with the 4.5" lift. It is almost a bolt in exchange using all GM drivetrain parts.

tlannom 06-08-2011 08:03 PM

Thanks to everyone for all the input. Based on the comments so far, here are my comments/ concerns:

  • T5- Gone.
  • T18- Turns out my friend didn't have a T18. Not really leaning in this direction.
  • NV4500- Love the durability. Not all that concerned about the price but REALLY concerned about the fit and modifying the transmission tunnel.
  • automatic choices- maybe cheaper and durable but really enjoy the third pedal. Not really leaning toward going to automatic.
  • SM465- leaning in this direction for a couple of reasons. Fit and gearing. Looks like I won't have to regear the Dana 300 or the axles if I go with this choice.
I think I may let a local 4X4 shop put everything back together. Depending on what they say and the expense, I may go with the NV4500. If it's too expensive and I have to do it my self, then it sounds like the SM465 may be a better option. I really appreciate all the comments. Keep 'em coming. I will keep you guys posted.

Thanks

JeepnBlake 06-08-2011 11:00 PM

You may consider the sm420 as well, the older similar version of the sm465. Both of which will likely require adapters to adapt to your transfer case.

kickingprop 06-09-2011 06:54 AM

Quote:

Originally Posted by jeepdaddy2000 (Post 11677998)
I tend to agree with this statement. Running 3.73's with 33's puts you in the ball park for a straight four speed. It also allows for larger tires in the future and eliminates the need to regear to 4.88's as the op is looking to do. The SM is a short trans and the adapter is small as well. The overall short length will help keep that rear driveline as long as possible, an issue with the 4.5" lift. It is almost a bolt in exchange using all GM drivetrain parts.

Quote:

Originally Posted by tlannom (Post 11678171)
  • SM465- leaning in this direction for a couple of reasons. Fit and gearing. Looks like I won't have to regear the Dana 300 or the axles if I go with this choice.

:agree: :ditto: :thankyou: :highfive: :thumbsup: :thumbsup:


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