NV4500 swap into 90 suburban

[Isaacm2228]

Hello, so I have a 1990 suburban with a 6.2 and TH400 and I’m looking to swap it out for an NV4500 I got out of a 93 2500. When it comes to driveshafts, am I gonna have to go custom or are there any specific trucks I can grab them out of for a straight swap?

 

[scouthead]

no clue! but you are about to build a truck I've always wanted!


local drive shaft shops should be able to just take your existing driveshafts and retube and balance them fairly quick and inexpensively.

 

[Wes Harden]

Welcome @Isaacm2228.
It has been done B4 and I'm sure someone will pipe in.
But if your over all transmission length including t case adapter changes, your drive shafts will need to be adjusted.
What t case are you using? Will you keep a slip yoke, or change to a slip yoke eliminator?

 

[HankScorpio]

The pedal set for a suburban with a hydraulic clutch is getting pretty hard to find. You might start there.

 

[sweetk30]

85-91 square body for pedal set . Then use flex hose with metric bubble flare union . Extra bubble flair nut and shorten the nv4500 hard line and flair on with the bubble . Route over bell housing .

Use a big pair of c-clamps to hold the slave pistion in 3/4 of its travel . Then bleed clutch and reinstall slave .

I did this 1 time no problems .

There is vac brake or hydro boost brake for the pedal setup . Try and match up . If you cant easy mod around it .

 

[ZooMad75]

I don’t know the overall length of the th400 from the bellhousing flange to the t-case mounting flange on the t-case adapter, but I can tell you it was under 1/2” different than the 700r4 I took out my ‘91 when we put a nv4500 in mine. I didn’t have to change shaft length on either front or rear shafts and the cross-member didn’t have to move either.

On a 400 it will depend if you have the short or long adapter to the t-case.

As far as the pedals go, you should put an ad in the classified section and start your hunt now. Hydraulic clutch pedal sets don’t grow on trees and get priced accordingly. Don’t be shocked at a price of $500 or more for a set. That’s the going rate to gain a man pedal. Also, be aware of creeps that don’t share the fact the pedal set they have are mechanical and not hydraulic. You won’t find that here of course but on Facebook marketplace or Craigslist. If you don’t see two support rods coming from the main pivot shaft that would normally go to the firewall, it’s not the right set. Non-hydraulic pedals lack the support rods. If you are unsure just post a pic up here and one of us can chime in to tell you what they are.

 

[ccj8008]

First year for GM hydraulic clutch is 1985. Confirm what Zoomad said on the length of the NV4500 setup vs 700R4 and TH400 adapter. I swapped an NV4500 into my 1991 Suburban without driveshaft mods. I did make my own hydraulic line connection after living with a funky conglomerations of fittings used for the initial connection. I loved driving that Burb after the swap! I tried getting a new chip burned but ended up getting a new/used computer from a manual truck to deal with the removal of the AT.

 

[campfire]

I've done the 6.2 diesel automatic --> 5-speed swap twice (see both threads in my sig. line).

To answer your first question, a 1990 4WD TH400 should have the same flange-to-flange length & spline count as a 1993 NV4500. I did the same swap to my '86 Blazer and my crossmember still lined up with the original frame holes. No drilling required (for that portion). Your truck has a newer style of crossmember, but the transmission mount geometry is identical.

I also retrofitted a stock squarebody hydraulic clutch bell housing (1985 and newer) to my early-style NV4500. It does require drilling, but aside from that it allows you to stick with 100% stock GM squarebody clutch parts. No funny hydraulic adapters, no having the clutch slave wedged against the oversized diesel starter motor.


I've run into many (probably most) of the problems one can encounter swapping from TH400 --> NV4500, so feel free to ask more questions as you go.