700R4 Swap Into M1009

[Recovry4x4]

Need to change the input gear of the transfer case from the current 32 spline to a 27 spline input.

 

[Whitfield]

Thanks guys! With all the talk of Input shaft spline count, I guess I was confusing them with the tail shaft spline count.

 

[dmilkman589]

I put a 700 in my M1028. I had to buy an adapter from, I believe, Advanced Adapters. With this adapter, I did not need to change drive shaft lengths and I was able to keep the stock tail shaft mount. The adapter included a spacer to go in between the tail of the trans & the stock tail shaft spacer/mount. Also came with correct spline to install in the 700 to mate it up to my T-Case. Truck runs way better on the HWY now.

What part number? And price?

 

[vanaisa]

Old topic but still relevant. I have ´86 M1009. All stock, exept 33" tires. Technically fine, some rust on body, nothing serious.
It is great in our forest roads etc but from time to time i´d like to drive it on highway. For my liking revs are too high at 110...120kmh (68...75mph) and lets face it, 55mph is just slow for longer trips.

My question is - is it wiser to buy GearVendors OD unit and put it behind TH400 or still go with TH700R swap? (money-wise sure both are slightly stupid but this is not question right now). As i understand, with my gearing TH700 is not preferred?

And - if GearVendors - how it holds on not too heavy offroading?

 

[chevymike]

I am running a Gear Vendors OD and comfortably cruise at 65 mph and can get to 75-80 mph in my M1010 (flying brick). It works nice but it is still not going to give the truck a modern vehicle feel as far as driving speeds. It does help and I like that I can split gears when climbing grades. Having a gear between 2nd and 3rd (i.e. 2.5) is nice. At 65mph on 255/85-16 tires, it is about 2600 rpm's.

As for offroad, it has a 4WD lockout so the OD cannot be used when in 4x4. For offroad, you're likely just going to turn it off anyways so it really is no different than not having it.

 

[vanaisa]

Thanks for reply Mike!
Yes, i dont assume modern truck feel, just lower rpm on tarmac. If your M1010 have 4.56:1 ratio, then i can probably see with my 3.08:1 rpms close to raceptable 1800ish with 65mph speeds. This is good.

On offroad, is OD unit will be safe, i.e. not hanging too low or otherwise prone to breaking? Havent seen it installed...

 

[chevymike]

Ah, missed the fact you have a M1009. Yes, my M1010 is still on 4.56 so your 3.08 would be nice for the OD. Here is a pic installed. It sits up higher than the transfer case. One thing to note though, it shortens your driveshaft about 16". On the longer wheelbase truck its not a big issue but the shorter M1009 it might be. Might want to check how long your driveshaft is and subtract 16" and see how long it would be. Might be too short or put the u-joint angles too steep.

 

[vanaisa]

Thanks, good hint about driveshaft, will measure it tomorrow.
If angle will be too big, i probably can use double u-joint shaft, like on my ´74 Cherokee front driveshaft. Will be weaker but this is first thing that come to my mind.

 

[chevymike]

Thanks, good hint about driveshaft, will measure it tomorrow.
If angle will be too big, i probably can use double u-joint shaft, like on my ´74 Cherokee front driveshaft. Will be weaker but this is first thing that come to my mind.

If you go that route, definitely do like I did and get a fixed yoke output. Slip yoke and double u-joints don't play well together.

 

[Sharecropper]

I will double-ditto everything ChevyMike said, however I would like to add, in my opinion, your stock 6.2 with 3.08 gears will not have enough muscle to get you up those long hills in a fourth gear, regardless if it is a Gear Vendors overdrive or 700R4. You will be fine on flat land not too far from seal level without a heavy load, but when you load that M1009 up with people and equipment, and then maybe hook to a trailer, and then head for the mountains, I will predict that you will be wishing you had all that cash back. Just my 2 cents.

If I were you, I would invest in a Tiny Tach (if you do not already have a tachometer) and see what your highway speed is at 2200 RPM. That is the sweet spot for the 6.2. If your are not running fast enough at 2200 RPM, then increase your tire diameter (don't forget to adjust your speedometer reading with the larger tires). By keeping your M1009 stock drivetrain you will also be maintaining it's value as well. Once you start modifying the OEM driveline, the resale value begins to drop off.

I will predict that you will be happy with tall skinny tires.

Hope this helps.

 

[vanaisa]

No, i dont have tachometer, rpms measured "by ear" - probably not best way of course.
Estonia is flat and ca 50 metres from sea level everywhere so no driving problems. Only two "real" mountains
And i usually dont carry anything heavy. What i found - without roof truck runs way better, it is quicker from start and overall more nimble.
8 months of s**** ski weather, as we have here, i still drive without roof if even slightly possible

OEM tires are 31", i have 33" now and as i understand bigger ones dont fit anymore without rubbing. And to my eye, 33" looks best on this truck.
I dont worry about resale value, i never sell this truck. But i like to keep things as original as they are.

Well, not really original, as there is winch installed and electrics are converted to 12V.

 

[Sharecropper]

No, i dont have tachometer, rpms measured "by ear" - probably not best way of course.
Estonia is flat and ca 50 metres from sea level everywhere so no driving problems. Only two "real" mountains
And i usually dont carry anything heavy. What i found - without roof truck runs way better, it is quicker from start and overall more nimble.
8 months of s**** ski weather, as we have here, i still drive without roof if even slightly possible

OEM tires are 31", i have 33" now and as i understand bigger ones dont fit anymore without rubbing. And to my eye, 33" looks best on this truck.
I dont worry about resale value, i never sell this truck. But i like to keep things as original as they are.

Well, not really original, as there is winch installed and electrics are converted to 12V.

Whatever. It’s your vehicle, do as you wish. You joined this forum and asked for advice. ChevyMike and I offered advice. It’s up to you to heed the advice or not. I am finished with this thread. Good luck.

 

[vanaisa]

Hey, why so grumpy? I am grateful for the suggestions, they are big help and valuable information for me. That i´m not concerned about hills or loads, well this is my problem. Another problem is, that we dont have here partsyards as you have there and to find parts for TH700 swap is almost impossible.
OK, measured driveshaft - from u-joint eye to other ends eye it is 29.527" So if i add 16" (OD unit), angles will be too big. I dont think that double joint driveshaft will be holding there too.
So, seems that TH700 is best option for my M1009. Back to drawingboard.

 

[chevymike]

Honestly, before I would spend the money on doing an OD in a M1009, since you already have 3.08 gears (versus 4.56 of the other M10xx series), I would do like suggested and get a Tiny Tach (which I had in my first M1010) and get some real RPM numbers.

Based on 3.08 gears, 33" tall tires at 65 mph, you should be right around 2100 rpm's, which is great. To give you reference, same specs but with 4.56 gear you would be around 3100 rpm's which is way higher than I would want and why I put the Gear Vendors in.

Not really sure I would spend the money on an OD for a M1008 since you already have a low ratio to begin with.

 

[chevymike]

Also keep in mind, IF you do go for a 700R4 trans, you need to have the special, very rare and hard to find, TV cable bracket that goes between the injection pump and the TV cable at the back of the engine. Before thinking about a 700R4, get this bracket FIRST.

 

[vanaisa]

Thanks! Already sent order email - TinyTach has dealer in France, so should arrive pretty quick. I´d like some day to find tach what fits to cluster...
Is this correct one?

 

[chevymike]

Yeah, that looks like the correct TV bracket.

 

[ehuppert]

70 mph is roundabout 2200 rpm with 3.08s. "Back in the day" we ran over the road with CUCV's, 80 mph plus is not a real comfortable or safe speed with the Blazers! BTDT allot!

700r4 is going to spend allot of normal use in 3rd gear, really negating the cost of a swap! Stick with what you've goy for now and spend money elsewhere on the vehicle!

 

[Sharecropper]

700r4 is going to spend allot of normal use in 3rd gear, really negating the cost of a swap! Stick with what you've goy for now and spend money elsewhere on the vehicle!

I agree with ehuppert. A 700R4 with 3.08 gears will stay in 3rd gear most of the time. Especially if there is any load in the vehicle. Or headwind. Not being grumpy, just realistic. Save your money and stay with what you have.

 

[vanaisa]

I do not doubt your words. Lets see, what tach shows when it arrives. To my ear engine rpm´s are too high, bad ears probably.
At the same time i located ´91 small Blazer (gas engine, TH700 and 4WD, so NP241?). Cheap, as it is rust bucket. So if needed, i have tranny and transfer case.
And sorry, for wrong topic - LMC have tach conversion kit what fits to cluster (36-1872) - is it worth its price? And is this tach needs adjusting?