toploader interchange

flexiclese · May 30, 2007

can a toploader for an FE engine (390/427/428) bolt up in place behind a 429/460? Using a 429 bellhousing/clustch setup. are the bolt patterns and tranny input length the same? 69-73 429 toploaders are tough to find.
thanks in advance.

RogerC62 · May 30, 2007

I don't think the 385 big block toploader is interchangeable with the FE big block toploader. I believe the input shaft is larger on the 426/460 version. I seem to remember reading that somewhere. I'm sure you can verify it somewhere on the net but I can't think of the site right now.

rbohm · May 30, 2007

you can but the input shaft on the FE top loader is shorter than the 429/460-small block top loader trans. the daytona top loaders did have a larger diameter input shaft, but they were installed on the boss 429 and the scj 429. the others got the smaller input shaft.

D.Hearne · May 30, 2007

All the Toploaders used the same bolt pattern and two input sizes (1-1/6" x 10 spline or 1-3/8" x 10 spline) the thing to watch for is the two different input shaft lengths, the big block 1-3/8" and 390 specific Toploader use the shorter input , the front portion forward of the splines is shorter by about 1/2" to 5/8". The 390 Toploaders had the smaller diameter input and short front snout. As far as I know all the large input big block Toploaders also had the short front snout. The splined portion is the same for all.

dennis112 · May 30, 2007

There are actually 2 possible bolt patterns for the toploader. The early 64-65' bellhousing had holes spaced closer than the later models, and the toploader was built to match with short mounting ears. Late 65' and newer toploaders have both the original narrow pattern plus the more common wide bolt pattern.

Here is an example of both patterns on a newer toploader:

Here is an example of the 2 driveshaft lengths:

View attachment 383496

flexiclese · May 31, 2007

D.Hearne said:
All the Toploaders used the same bolt pattern and two input sizes (1-1/6" x 10 spline or 1-3/8" x 10 spline) the thing to watch for is the two different input shaft lengths, the big block 1-3/8" and 390 specific Toploader use the shorter input , the front portion forward of the splines is shorter by about 1/2" to 5/8". The 390 Toploaders had the smaller diameter input and short front snout. As far as I know all the large input big block Toploaders also had the short front snout. The splined portion is the same for all.

So if I understand you correctly a '67-73 427/428 toploader will bolt up behind a 69-73 429/460 bellhousing? The input shaft splines, diameter and length will all work together. But a 390 may not?
Thanks for all your replies.

Rusty67 · May 31, 2007

If they are internally all the same couldn't you just swap out the bearing retainer/ input shaft and have what you need ?

dennis112 · May 31, 2007

Rusty67 said:
If they are internally all the same couldn't you just swap out the bearing retainer/ input shaft and have what you need ?

That is correct as long as your new input shaft matches the gear ratio of the tranny--(either 2.78 or 2.32.) These 2 type of input shafts have different # of gear teeth.

D.Hearne · Jun 1, 2007

Dennis is correct, I didn't include the earlier bolt pattern cause there's not that many in circulation. Swapping the input may also wind up with gear noise from different wear patterns between the gears. I had one Toploader built with parts from three and while they had the correct ratio gears, the wear was different and I ended up with a transmission that made an excellant imitation of a roots blower when driven.

D.Hearne · Jun 1, 2007

flexiclese said:
So if I understand you correctly a '67-73 427/428 toploader will bolt up behind a 69-73 429/460 bellhousing? The input shaft splines, diameter and length will all work together. But a 390 may not?
Thanks for all your replies.

Yea, that's correct. Just watch the input lengths and make sure the front snout goes into the pilot bearing when it's all bolted together.
The 390 Toploaders will also bolt up to the other bells, the input shaft is just a smaller diameter, you'd need a small block type clutch for it but with a diameter to match the flywheel. The GT390's used a 11 or 11.5 clutch disc with the smaller input shaft splined center.

flexiclese · Jun 2, 2007

thanks for all you info guys. much appreciated

fastback brian · Jun 4, 2007

One last option, re-tip the input shaft. Ive done this a few times on them big spline shafts to fit my small block. A good re-tip will outlast the rest of the input shaft. Cost me about bewtween 50-100 for a re-tip.

Rusty67 · Jun 4, 2007

fastback brian said:
One last option, re-tip the input shaft. Ive done this a few times on them big spline shafts to fit my small block. A good re-tip will outlast the rest of the input shaft. Cost me about bewtween 50-100 for a re-tip.

This does actually work but I wouldn't trust anyone to do it unless they had a great reputation.

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