Speed Gems Transmission Adapters

Speed Gems Transmission Adapters Speed Gems Transmission Adapters We are currently building adapters for many of the great but overlooked nostalgic motors of the ‘50’s and ‘60’s. YUCK.

Over the years, many rodders have switched their cars over to small block Chevy motors simply because there weren’t any decent transmissions available for the motor that was already in the car. Who could blame them? After all, why would you keep a 394 Olds if all you could run behind it was a Slim Jim? Or, a 401 Buick Nailhead with a Dynaflow? How about a ’53 331 Hemi with a Fluid Drive? Bendtsen’

s Transmission Adapters started as businesses often do, to fill a void or a need in a market place. We evolved from a full service transmission shop that grew to specialize in antique and obsolete transmissions. I started building engine to transmission adapters for two reasons. One is that it is getting extremely expensive to rebuild the old transmissions. Not only are some of the parts getting scarce (try buying a new sprag or roller clutch for a Dynaflow or Turboglide torque converter), but the knowledge level of the people available to rebuild these units competently is falling by the wayside. Transmissions had more internal changes back in the 50’s than they do today. Four speed Hydramatics to most people appear to be the same from the outside, but many of the internal parts (mostly hydraulic control) were not interchangeable from year to year, or from model to model. These transmissions had extremely touchy throttle pressure linkages that required them to be adjusted correctly or a failure would occur. Carburetor swaps usually made adjustments very difficult if not impossible. These adjustments are very similar to the detent cables used in 700R4 and other modern transmissions. They control all internal pressures inside the transmission. Throttle pressure must raise quickly when engine load increases. Out of adjustment one way (low pressure) and you will have burned clutches and bands. Out the other way (high pressure) and you can break shafts and splines. Vacuum modulators changed the way transmissions received their information about engine load. Linkage & cables became just “kickdown” devices. This is why people still don’t understand the difference or relationship as to why the 700R4 and similar transmissions require such precise adjustments, they are simply going back to the way things were 50 years ago! Electronics made external adjustments obsolete. There are no longer any mechanical adjustments. All pressure and shift timing is now taken care of by computer. Changes internally to today’s transmissions are usually well documented not only by the manufacturer, but also by technical subscription to a number of aftermarket companies. Not so in the past. When the old mechanics die, a lot of knowledge goes with them. I listen closely when I find an old transmission mechanic that still remembers fixes for old transmissions. The second reason that I’m designing and building adapters is that I would like to see more people run alternative engines in their cars rather than small block Chev motors. The V8 engines that many of us fondly remember from our youth are making a long overdue comeback in the way of the Resto-Rod. Personally, I loved 348’s and 409’s, but the Ford Flathead, the Buick Nail head, the Olds rocket, the Hemi’s, the straight 8’s, & many more popular multi-carb motors are all still very popular. Just check the number of websites on each of these different makes and you will find a huge following. Rodding started as a very creative hobby/sport. Working with what one could afford at the time, we all built our cars with a lot of imagination. This trend, of late, to plop a small block Chev motor into every rod built has made me feel that the hobby/sport has totally changed. Car shows are getting boring due to the rubber stamp/production line type of car building going on around the country today. Is anyone besides me tired of looking at what seems to be the same car over and over and over again? Every car in the world it seems has a Chev small block in it. I’m partial to seeing drive trains that are unusual. I like to see what the next guy has done to his car that no one else has ever done before. It doesn’t matter if it looks like it’s been cobbed together or if it even works, at least somebody tried something different. We here at Bendtsen’s Transmission Adapters plan to adapt the old motors of the ‘50’s and ‘60’s to modern transmissions, so you can use a motor with some personality/Attitude? I plan to lead a one-man revolution against the BORING and UNCREATIVE trend of planting small block Chevy motors into everything that moves. Enclosed you will find a small list of alternative nostalgic motors, along with a few new motors, that we now provide adapters for. Most of our adapters aren’t made by anyone else, anywhere. None of my adapters require any block or transmission case modifications! They are easy to bolt on at home. They are high quality, and expensive. Well worth the money.

Our popular Speed Gems Small Block Ford to Ford Modular Automatic Transmission Adapter Kit is available again — now back...
05/29/2026

Our popular Speed Gems Small Block Ford to Ford Modular Automatic Transmission Adapter Kit is available again — now back and better than ever.

Updates include:
* Thinner 1” adapter
* No torque converter spacer
* Factory small block Ford flex plate compatibility

Perfect for getting a 6R80 in your Windsor-powered F-150 or pairing a Modular automatic transmission with your 302 Mustang.

Premium American-made adapters. Built the Speed Gems way.

Real build. Real results.331 Hemi → A727WMO1301 adapterSwipe right→Thanks for the 5 star review Russell 👊📞 763-767-4480 ...
05/18/2026

Real build. Real results.
331 Hemi → A727
WMO1301 adapter

Swipe right→

Thanks for the 5 star review Russell 👊

📞 763-767-4480 🔗 Link in bio




05/06/2026

COMING SOON

Kit:FO2501
Ford 429/460 to Modular V8 Automatic

The big block Ford adapter is on its way!

Will work with 6R80, 4R70W, 4R75W, 10R80, 5R110, 4R100, or 6R140 (V8 gas case)

📅 Available end of May 📞 Questions or to get on the list: 763-767-4480

🔗 Link in bio

FO2701 Ford Small Block V8 to Ford Modular V8 AutoBack and better than ever. Our small block Ford to Modular V8 automati...
04/24/2026

FO2701 Ford Small Block V8 to Ford Modular V8 Auto
Back and better than ever. Our small block Ford to Modular V8 automatic kit is constructed from 100% USA sourced materials and machined right here in Waunakee, Wisconsin — fit, form and function second to none.

Limited Release Inventory
*Call 763-767-4480 with any questions on the kit or current availability.

Swipe through for a closer look ➡️

🔗 Link in bio

While we’re producing fewer bellhousings than we did back in the day, you can still pick up some of those original-style...
03/11/2026

While we’re producing fewer bellhousings than we did back in the day, you can still pick up some of those original-style pieces on our website while they’re available.

Torque vs Horsepower 
Do you know the difference and why it matters? New Speed Gems blog is live
*** Full article in our...
01/24/2026

Torque vs Horsepower 
Do you know the difference and why it matters?
 New Speed Gems blog is live
*** Full article in our bio

Thank you Aaron for the 5 star review and photo of our: TH10001 - 700R4 Short Extension Housing
01/08/2026

Thank you Aaron for the 5 star review and photo of our: TH10001 - 700R4 Short Extension Housing

MT1201 | 1995–98 Ford T5 to Chevy ’55+ bellhousing — proven fit, proven results. Thanks for the great review, Scott!!   ...
12/30/2025

MT1201 | 1995–98 Ford T5 to Chevy ’55+ bellhousing — proven fit, proven results. Thanks for the great review, Scott!!

12/20/2025

Merry Christmas and Happy New Year from Speed Gems! Here’s to an even bigger 2026 filled with killer builds and next-level engine swaps.|

Head over to our website 🌐transmissionadapters.com🌐 to shop Speed Gems adapter Kits and Wilcap adapter kits! We offer wo...
12/14/2025

Head over to our website 🌐transmissionadapters.com🌐 to shop Speed Gems adapter Kits and Wilcap adapter kits! We offer world-wide shipping, texting features - for easy communication & multiple payment options.
Have any questions?! We are here to help![email protected]

Address

806H S Division Street
Waunakee, WI
53597

Opening Hours

Monday 8am - 4:30pm
Tuesday 8am - 4:30pm
Wednesday 8am - 4:30pm
Thursday 8am - 4:30pm
Friday 8am - 4:30pm

Telephone

(763) 767-4480

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