Specifications

CONVERSION APPLICATION SUMMARY
JEEPS 1941-79
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conversion application summary (1941-79)
This section reviews some of the most common conversions that we deal with. The information is comprised from 34 years of
conversion experience, along with the valuable input we received from our customers. If you find any of this information outdated
or incorrect, please let us know. The information you provide may be useful in assisting others in the future.
1946-64 JEEP UNIVERSALS:
The Jeep Universal models CJ2A, M38, M38A1, CJ5 & CJ6 are popular vehicles for engine and transmission conversions. The
original T90 3 speed transmission can be retained, but will require changing the front input shaft. Since most of these vehicles were
originally equipped with a 4 cylinder engine, the clutch spline size and length will need to be increased for use with the new engine.
This new input shaft, Warner Gear #906203, is available only in an 18 tooth gear design. There are a few Jeeps that will require
the cluster gear change in order to use this new input gear. We stock this input gear under Part No. 716014. The adapter plate
is 2-5/8" thick and can be used with a standard car-type bellhousing. When selecting the bellhousing, you will have the option of
either a 12-7/8" or 14" inside diameter. If the smaller bellhousing is selected, then you will need to use the 153T flywheel. If the
larger bellhousing is selected, then you will need to use the 168T flywheel. Driveshaft modifications and transfer case relocation
is normally required when replacing 4 cylinder engines. The stock steering mechanism can be retained, and the clutch linkage can
either be modified or substituted with our chain control kit. The exhaust
systems can be either stock manifolds or the A/A header systems. The
engine location must be offset 1" towards the driver's side of the vehicle to
allow for front driveshaft clearance around the starter motor. The engine must
be kept as high as possible to allow for this front driveshaft clearance. On
square fender Jeep installations, you may be required to modify the firewall
for distributor clearance. The radiator will need to be increased in size and
possibly remounted so that it is flush with the front grille. The original front
crossmember that the steering bellcrank is mounted on can either be
removed or sectioned for clearance for the new engine oil pan. The use of
our Saginaw steering conversion kits will eliminate the need of the stock
steering bellcrank. If the original crossmember is going to be removed, it
should be replaced with a new crossmember directly beneath the grille area.
The transfer case is a Dana Model 18, and we offer numerous optional
transmission-to-transfer case adapters. If your T90 is in marginal condition,
we suggest that you consider using an optional OEM type transmission.
A. Transmission Assembly: If you have decided to keep the T90 transmission, it should be completely disassembled and
inspected for any worn parts. It is recommended that new bearings and transmission synchronizer rings be installed. The adapter
kit is provided with a new front bearing retainer that bolts directly to the front of the T90 transmission. The seal inside the retainer
will need to be positioned directly over the ground surface of the new input shaft with the open side towards the transmission. Some
stock input shafts were designed with the seal located further out on the input shaft. This particular design will periodically have
seal failure, which is caused by the rough unfinished seal surface beneath the seal location on our new retainer.
B. Transfer Case Assembly: Whether you are retaining the T90 or installing a new transmission, you will need to remove the
Dana 18 transfer case. At this time, you should inspect the transfer case for any excessive wear. The intermediate shaft in the transfer
case is probably overdue for new bearings and a new counter shaft.
C. Engine Location: The engine must also be offset 1" towards the driver's side of the vehicle. This offset is limited to the
clearance between the stock manifold and original steering box. This offset will allow additional driveline clearances for the front
driveshaft. The engine mount brackets can be either welded or bolted into position. We recommend trial fitting the engine position
prior to final assembly. Things to take into consideration are height of engine, distributor, and radiator clearance. On most early
Jeeps, slight firewall modifications are required.
D. Crossmember Support: With the engine centerline being offset, you must now move the transmission and transfer case
support towards the driver's side by an equal amount. This can be accomplished by either moving the mount over on the existing
crossmember, or by trimming the necessary amount needed on the driver's side and rewelding it to the passenger side. Make sure
that all welds are gusseted for maximum strength. Since driveline modifications are normally necessary, the transfer case and
crossmember support will also need to be relocated on the frame rails. You will need to drill new mounting holes on your frame
to reposition the crossmember support.
E. Clutch Mechanism: We recommend the GM cast iron clutch release lever for all Jeep conversions. It may be necessary
to shorten the lever if the stock brake master cylinder is still being used. The clutch linkage between the transfer case and frame