M1008 harsh and late 1-2 and 2-3 shifting

[Enforced_Leo44]

'85 M1008 new owner here, I have had her for about a week now and I'm getting pretty worried by the harsh and late shifts that the tranny is doing, almost like as if the vacuum modulator isn't getting vacuum/isn't working, because no matter the engine load, the tranny shifts out of 1st at about 15mph and out of 2nd at about 25-30mph.
Previous owner states that a shift kit has been installed, and within the stuff that he gave me with the vehicle itself, there is a TransGo reprogramming kit box with a bunch of stuff in it(usual various springs, VB separator plate that looks untouched and gaskets and a 2-3 accumulator piston).

PO also said that he didn't do any of the work and he's just stating what the previous owner (before him) told him that he did, so I'm not 100% certain that there actually is a shift kit installed.

Can a TransGo reprogram kit make the tranny act as if the modulator wasn't working properly? And if so, can I revert back to a stock VB without issues?

Thanks in advance, any advice is gladly appreciated!

 

[Barrman]

I don’t know what the Transgo can and can’t do.

CUCV wise. The vacuum pump at the rear middle of the engine has a hose that goes to the throttle vacuum valve on the passenger side of the injection pump. Then a hose and line go to the vacuum modulator on the side of the transmission. A little unseen crack in any of those 40 year old vacuum hoses could cause shifting problems. I would suggest checking vacuum at All connections first and replacing any hoses that look like they might think about cracking.

 

[WWRD99]

So post pics of what's left of the transgo kit plus it's number. Shifting wise 15 mph into 2nd and 35 into 3rd is about normal with light throttle. Does it shift higher with more throttle? Define harsh...like bang shift or just firm. What vacuum inlbs at the modulator do you have at idle.

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[Enforced_Leo44]

So post pics of what's left of the transgo kit plus it's number. Shifting wise 15 mph into 2nd and 35 into 3rd is about normal with light throttle. Does it shift higher with more throttle? Define harsh...like bang shift or just firm. What vacuum inlbs at the modulator do you have at idle.

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By harsh I mean it chirps tires while getting out of 1st gear, and gives a solid kick while getting out of 2nd.
Shifting range doesn’t seem to change much in relation to throttle position.
I’ll send a pic of the stuff left in the TransGo kit

EDIT: the tires are some beefy 37’s

 

[Enforced_Leo44]

This is what’s left of the kit

 

[WWRD99]

By harsh I mean it chirps tires while getting out of 1st gear, and gives a solid kick while getting out of 2nd.
Shifting range doesn’t seem to change much in relation to throttle position.
I’ll send a pic of the stuff left in the TransGo kit

EDIT: the tires are some beefy 37’s

Ok...if it's shifting that hard then it's definitely not a modulator issue. To mild it out you'd have to drop the valve body and put the mild colored springs from the kit in. Looks like they popped the pressure valve out and swapped it too. Without the kit part number it's hard to guess exactly what they could have done. Hopefully drilling the valve body wasn't an option but to make it hit that hard it usually does. If you're into trans work dropping the valve body isn't that hard...just very messy. If not a basic trans shop shouldn't have a problem tuning it down pretty quick. I assume you have a 208 transfer case...that little chain isn't designed for chirping 37s...that's gotta be nuts hearing that though...the 400 will handle it though. Could always swap in a 205 that would handle that large tire and shift load better.

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[Enforced_Leo44]

Ok...if it's shifting that hard then it's definitely not a modulator issue. To mild it out you'd have to drop the valve body and put the mild colored springs from the kit in. Looks like they popped the pressure valve out and swapped it too. Without the kit part number it's hard to guess exactly what they could have done. Hopefully drilling the valve body wasn't an option but to make it hit that hard it usually does. If you're into trans work dropping the valve body isn't that hard...just very messy. If not a basic trans shop shouldn't have a problem tuning it down pretty quick. I assume you have a 208 transfer case...that little chain isn't designed for chirping 37s...that's gotta be nuts hearing that though...the 400 will handle it though. Could always swap in a 205 that would handle that large tire and shift load better.

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I actually do have a np205 in it, twin stick, and a GV unit that’s probably what’s suffering the most.
Regarding the kit number, there is no documentation left in the box, maybe I could look for a receipt, other than that there is a VHS with manuals and stuff.

 

[Enforced_Leo44]

So, since it's pretty clear that the kit has been installed, and the only way forward is to take the valve body out and inspect it, can I remove the VB while the tranny is still in the vehicle? Wouldn't the checkballs just fall out?

 

[WWRD99]

So, since it's pretty clear that the kit has been installed, and the only way forward is to take the valve body out and inspect it, can I remove the VB while the tranny is still in the vehicle? Wouldn't the checkballs just fall out?

Yup can take it out in the truck. Yes the check balls will come out but the ones in the valve body stay in it and the ones in the case should stay in if you leave the top plate bolted in. It's a very messy job but not hard. The check balls would have to go in where the kit said so not the stock locations...many times the plate is plugged and they're left out. If you put the old plate in you'd need a stock gasket and stock check ball locations. I'd be curious if they bumped line pressure up.

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