Transmission Pre-Installation Checklist
A used transmission fails for one of four reasons: dirty cooler flow, the wrong fluid, reused wear parts, or no programming. Work through every step below before the vehicle moves — this is also what keeps your 180-day warranty valid.
Written by our own installers. Ask us anything before you turn the key.
The one decision that ends most claims.
When a transmission fails, it fills the cooler and the cooler lines with clutch material and metal. That debris does not come out with a drain. Bolt a good used unit onto an unflushed cooler circuit and it will be contaminated within minutes of the first drive — before you ever leave the shop.
Reusing the radiator's internal cooler
The cooler tank sits inside the radiator. Debris packs into passages you cannot reach, see, or verify. A flush gun pushes some of it out and leaves the rest waiting.
External cooler, or a brand-new factory cooler
Bypass the radiator cooler with an external cooler, or fit a new factory unit. Either way the circuit is clean and provable — and the receipt is the evidence if you ever need the warranty.
Check the manufacturer's latest TSB first. Several makes have a specific flush procedure, a required flow rate at the return line, or a mandatory radiator replacement after an internal failure. Where the TSB and this page disagree, follow the TSB — and keep a copy of it with your paperwork.
Get the install exactly right.
Transmissions are unforgiving about cooling, fluid and programming. Work through these six steps in order — every one of them is part of keeping the warranty valid.
What's covered, and what isn't.
Every unit ships with a 180-day warranty. It covers the transmission. It does not cover what happens to the transmission when the install skips a step above.
Internal failure of the unit
- ✓ Gears, bearings, shafts and planetary sets
- ✓ Clutch packs, bands and internal seals
- ✓ Valve body faults and internal solenoids as supplied
- ✓ Pump failure that is not caused by an unseated converter
- ✓ Internal leaks from a seal inside the case
- ✓ A unit that arrives damaged or does not match the VIN we quoted
- ✓ Case cracks or porosity found on arrival, before install
- ✓ A documented, correctly installed unit that fails inside the warranty period
Damage caused by the install
- ✕ No external cooler fitted, or the old internal cooler reused
- ✕ Cooler lines not flushed, or flow not verified
- ✕ Wrong fluid, universal fluid, or the wrong level
- ✕ Old filter, pan gasket or external seals reused
- ✕ Converter reused from the failed unit, or not fully seated
- ✕ No TCM flash and no adaptive relearn
- ✕ Overheating, towing beyond the vehicle's rating, or racing use
- ✕ Driving on after a fault, noise or warning light appears
- ✕ Fitted without an invoice from a licensed repair facility
- ✕ Physical, impact or fire damage after delivery
A claim is only as good as the paperwork.
If you ever need the warranty, these four documents are what we ask for. Collect them on the day of the install — chasing them a month later is what slows a claim down.
Installation invoice
From a licensed repair facility, showing the VIN, the date, the labour lines and the shop's details.
Fluid receipt
Showing the exact specification and the quantity used — this is the first thing checked on any clutch-related claim.
Cooler and flush receipt
The external cooler or new factory cooler, plus the flush line on the invoice. No cooler evidence, no claim.
Programming receipt
The flash and relearn line from your shop or the dealer, with the software level and the date.
30 checks, ticked off as you work.
Tick them here on your phone, or print the sheet and sign it. Either way, keep it with the invoice — a signed sheet answers most of the questions a claim would otherwise raise.
Transmission pre-installation tick sheet
American Motor Supply · keep with the installation invoice
The four-point sign-off.
Confirm all four before the vehicle moves. If any one of them isn't done, stop and fix it first — it is far cheaper than pulling the transmission back out.
Cooler sorted
External or new factory cooler fitted, lines flushed, flow verified.
Correct fluid
Right specification, right quantity, level set at the specified temperature.
New wear parts
Filter, pan gasket, external seals and the torque converter all sorted.
Programming done
Flashed, adaptives reset, relearn drive completed, codes clear.
Ask us before you turn the key.
Every install is a bit different. If anything on this page isn't clear for your transmission, talk to a real specialist first — we would much rather answer a question than process a claim.